期刊文献+
共找到681篇文章
< 1 2 35 >
每页显示 20 50 100
Overexpression of EspL inhibits autophagy and antigen presentation to promote the intracellular survival of Mycobacterium tuberculosis avirulent strains
1
作者 Luxia Cai Yingying Lei +6 位作者 Tianyi Xie Yiling Liu Yutong Fan Bing Yang Shuang Dong Gang Cao Xi Chen 《Animal Diseases》 2025年第1期43-55,共13页
Mycobacterium tuberculosis(Mtb)employs multiple mechanisms,such as phagocytosis and autophagy,to evade innate immune clearance and establish infection.In the present study,we identified the ESX-1 secretion-associated ... Mycobacterium tuberculosis(Mtb)employs multiple mechanisms,such as phagocytosis and autophagy,to evade innate immune clearance and establish infection.In the present study,we identified the ESX-1 secretion-associated protein EspL,which promotes Mtb survival by inhibiting phagosome maturation and autophagy initiation.EspL knockout decreased Mtb intracellular survival,while EspL overexpression increased bacterial survival by interfering with phagocytosis and autophagy.EspL interacts with ULK1 and promotes its phosphorylation at Ser^(757),leading to the inhibition of autophagy initiation.Additionally,overexpression of EspL reduced antigen presentation and T-cell responses both in vitro and in vivo.Our findings revealed that EspL interferes with autophagy and antigen presenta-tion by suppressing ULK1 activation.These insights provide a novel understanding of Mtb pathogenicity. 展开更多
关键词 Mycobacterium tuberculosis EspL PATHOGENICITY AUTOPHAGY Antigen presentation T-cell responses
原文传递
In‑Operando X‑Ray Imaging for Sobering Examination of Aqueous Zinc Metal Batteries
2
作者 Yuhang Dai Hongzhen He +4 位作者 Mengzheng Ouyang Jianuo Chen Jie Lin Haobo Dong Guanjie He 《Nano-Micro Letters》 2026年第3期330-337,共8页
Aqueous zinc metal batteries(AZMBs)face significant challenges in achieving reversibility and cycling stability,primarily due to hydrogen evolution reactions(HER)and zinc dendrite growth.In this study,by employing car... Aqueous zinc metal batteries(AZMBs)face significant challenges in achieving reversibility and cycling stability,primarily due to hydrogen evolution reactions(HER)and zinc dendrite growth.In this study,by employing carefully designed cells that approximate the structural characteristics of practical batteries,we revisit this widely held view through in-operando X-ray radiography to examine zinc dendrite formation and HER under nearpractical operating conditions.While conventional understanding emphasizes the severity of these processes,our findings suggest that zinc dendrites and HER are noticeably less pronounced in dense,real-operation configurations compared to modified cells,possibly due to a more uniform electric field and the suppression of triple-phase boundaries.This study indicates that other components,such as degradation at the cathode current collector interface and configuration mismatches within the full cell,may also represent important barriers to the practical application of AZMBs,particularly during the early stages of electrodeposition. 展开更多
关键词 Aqueous Zn metal batteries X-ray imaging In situ characterization Degradation mechanism
在线阅读 下载PDF
Effective nucleus-nucleus potentials for heavy-ion fusion reactions
3
作者 Ning Wang Jin-Ming Chen Min Liu 《Nuclear Science and Techniques》 2025年第2期103-111,共9页
Based on the Skyrme energy density functional and reaction Q-value,this study proposed an effective nucleus-nucleus poten-tial for describing the capture barrier in heavy-ion fusion processes.The 443 extracted barrier... Based on the Skyrme energy density functional and reaction Q-value,this study proposed an effective nucleus-nucleus poten-tial for describing the capture barrier in heavy-ion fusion processes.The 443 extracted barrier heights were well reproduced with a root-mean-square(RMS)error of 1.53 MeV,and the RMS deviations with respect to 144 time-dependent Hartree-Fock capture barrier heights were only 1.05 MeV.Coupled with the Siwek-Wilczyński formula,wherein three parameters were determined by the proposed effective potentials,the measured capture cross sections at energies around the barriers were reasonably well reproduced for several fusion reactions induced by nearly spherical nuclei as well as by nuclei with large deformations,such as^(154)Sm and^(238)U.The shallow capture pockets and small values of the average barrier radii resulted in the reduction of the capture cross sections for 52,54Cr-and 64 Ni-induced reactions,which were related to the synthesis of new super-heavy nuclei. 展开更多
关键词 Nucleus-nucleus potential Fusion reactions Superheavy nuclei Capture cross sections
在线阅读 下载PDF
Dietary supplementation of valine,isoleucine,and tryptophan may overcome the negative effects of excess leucine in diets for weanling pigs containing corn fermented protein
4
作者 Andrea P.Mallea Charmaine D.Espinosa +3 位作者 Su A Lee Minoy A.Cristobal Leidy J.Torrez‑Mendoza Hans H.Stein 《Journal of Animal Science and Biotechnology》 2025年第1期267-281,共15页
Background Diets with high inclusion of corn co-products such as corn fermented protein(CFP)may contain excess Leu,which has a negative impact on feed intake and growth performance of pigs due to increased catabolism ... Background Diets with high inclusion of corn co-products such as corn fermented protein(CFP)may contain excess Leu,which has a negative impact on feed intake and growth performance of pigs due to increased catabolism of Val and Ile and reduced availability of Trp in the brain for serotonin synthesis.However,we hypothesized that the negative effect of using CFP in diets for weanling pigs may be overcome if diets are fortified with crystalline sources of Val,Trp,and(or)Ile.Methods Three hundred and twenty weanling pigs were randomly allotted to one of 10 dietary treatments in a com-pletely randomized design,with 4 pigs per pen and 8 replicate pens per treatment.A corn-soybean meal diet and 2 basal diets based on corn and 10%CFP or corn and 20%CFP were formulated.Seven additional diets were formu-lated by fortifying the basal diet with 20%CFP with Ile,Trp,Val,Ile and Val,Ile and Trp,Trp and Val,or Ile,Trp and Val.A two-phase feeding program was used,with d 1 to 14 being phase 1 and d 15 to 28 being phase 2.Fecal scores were recorded every other day.Blood samples were collected on d 14 and 28 from one pig per pen.On d 14,fecal samples were collected from one pig per pen in 3 of the 10 treatments to determine volatile fatty acids,ammonium concen-tration,and microbial protein.These pigs were also euthanized and ileal tissue was collected.Results There were no effects of dietary treatments on any of the parameters evaluated in phase 1.Inclusion of 10%or 20%CFP in diets reduced(P<0.05)final body weight on d 28,and average daily gain(ADG)and average daily feed intake(ADFI)in phase 2 and for the entire experimental period.However,pigs fed the CFP diet supplemented with Val,Ile,and Trp had final body weight,ADFI,ADG and gain to feed ratio in phase 2 and for the entire experiment that was not different from pigs fed the control diet.Fecal scores in phase 2 were reduced(P<0.05)if CFP was used.Conclusions Corn fermented protein may be included by up to 20%in diets for weanling pigs without affecting growth performance,gut health,or hindgut fermentation,if diets are fortified with extra Val,Trp,and Ile.Inclusion of CFP also improved fecal consistency of pigs. 展开更多
关键词 Branched-chain amino acids Corn fermented protein LEUCINE Tryptophan VALINE Weanling pigs
在线阅读 下载PDF
Effects of spray dried plasma on litter growth performance and oxidative stress and inflammation of sows kept in a hot environment
5
作者 Hannah M.Bailey Natalia S.Fanelli +1 位作者 Joy M.Campbell Hans H.Stein 《Journal of Animal Science and Biotechnology》 2025年第3期1194-1206,共13页
Background Feeding spray dried plasma(SDP)to weanling pigs improves growth,but there is a lack of research on how SDP impacts oxidative stress and inflammatory response in lactating sows,and performance of their pigle... Background Feeding spray dried plasma(SDP)to weanling pigs improves growth,but there is a lack of research on how SDP impacts oxidative stress and inflammatory response in lactating sows,and performance of their piglets after weaning.Therefore,an experiment was conducted to test the hypothesis that sows fed a diet with SDP in late gestation and lactation have improved reproductive performance and reduced inflammation compared with sows fed no SDP.The second hypothesis was that pigs weaned from sows fed 0.5%SDP in lactation have reduced diarrhea incidence and improved growth performance during the initial 14 d of the nursery period regardless of dietary SDP.Results The percent of low vitality or starved pigs during lactation was less(P<0.05)from sows fed 0.5%dietary SDP compared with sows fed the diet without SDP.Dietary SDP did not influence oxidative stress markers in the plasma of sows,but serum cytokines increased(P<0.05)in sows fed the diet with 0.5%SDP compared with sows fed the diet without SDP.Pigs weaned from young sows fed no SDP or from mature sows fed 0 or 0.5%SDP had a greater gain to feed ratio when fed a phase 1 diet containing 6%SDP compared with pigs fed a diet without SDP,but the gain to feed ratio of pigs weaned from young sows fed 0.5%dietary SDP was not affected by dietary SDP in phase 1(interaction,P<0.05).Regardless of sow treatment,pigs fed a phase 1 diet with 6%SDP had greater(P<0.05)growth performance than pigs fed a phase 1 diet without SDP,and pigs fed the phase 1 diet with 6%SDP had reduced(P<0.05)diarrhea incidence in phase 1.Conclusions Feeding 0.5%dietary SDP to sows may reduce the number of mummified pigs and increase pig vitality during lactation,but adding 0.5%SDP to sow diets during lactation did not improve post-weaning performance of pigs fed a starter diet with 6%SDP. 展开更多
关键词 Cytokines LACTATION SOWS Spray dried plasma Weanling pigs
在线阅读 下载PDF
Feeding rumen-protected choline during the periconceptional period programs postnatal phenotype of suckled beef calves
6
作者 Masroor Sagheer McKenzie L.J.Haimon +9 位作者 Samuel Hincapie Montoya Daniella Heredia Federico Tarnonsky Mauro E.Venturini Angella Gonella-Diaza Nicolas DiLorenzo Joseph W.McFadden Gabriela Dalmaso de Melo Ky G.Pohler Peter J.Hansen 《Journal of Animal Science and Biotechnology》 2025年第4期1696-1703,共8页
Background Supplementation of choline chloride in culture medium programs the preimplantation bovine embryo to increase weaning weight of the resultant calf.Here,it was hypothesized that similar programming actions of... Background Supplementation of choline chloride in culture medium programs the preimplantation bovine embryo to increase weaning weight of the resultant calf.Here,it was hypothesized that similar programming actions of choline can be induced by feeding rumen-protected choline(RPC)to beef cows during the periconceptional period.Results A preliminary experiment was conducted to determine changes in circulating concentrations of choline and its metabolites after RPC supplementation.Suckled beef cows were individually fed 0,30,60,and 90 g of RPC(i.e.,0,8.6,17.3 and 25.9 g choline chloride)and blood samples were collected at random times after feeding.There were no differences in plasma concentrations of choline or its metabolites between groups.In the second experiment,effects of feeding 60 g/d RPC from d-1 to 7 relative to timed artificial insemination were examined for suckled beef cows.Feeding RPC did not affect pregnancy or calving rates,pregnancy losses,plasma concentrations of pregnancy-associated glycoproteins,gestation length or calf birth weight.Calves from RPC fed dams were lighter than control calves at~118 days of age(range 75–150;age included in the statistical model)and at weaning at~248 days of age.There was no effect of treatment on hip height at~118 days of age although there was a trend for RPC calves to be shorter at weaning.Weight/height ratio was lower for RPC than control at both 118 and 248 days of age.Treatment did not affect testis weight at~118 days of age.Conclusions Supplementation of RPC during the periconceptional period programmed development to alter calf phenotype in the postnatal period.The net result,reduced body weight,was the opposite of the phenotype caused by the addition of choline to embryo culture medium. 展开更多
关键词 Beef cattle CHOLINE PREGNANCY PROGRAMMING
在线阅读 下载PDF
Design and start-to-end beam dynamics simulation of the first super-radiant THz free-electron laser source in Thailand
7
作者 Natthawut Chaisueb Sakhorn Rimjaem 《Nuclear Science and Techniques》 2025年第7期222-235,共14页
A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation... A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation source requires relatively ultrashort electron bunches to produce intense coherent THz pulses.Three electron bunch compression processes are utilized in the PCELL accelerator system comprising pre-bunch compression in an alpha magnet,velocity bunching in a radio-frequency(RF)linear accelerator(linac),and magnetic bunch compression in a 180°acromat system.Electron bunch compression in the magnetic compressor system poses considerable challenges,which are addressed through the use of three quadrupole doublets.The strengths of the quadrupole fields significantly influence the rotation of the beam line longitudinal phase space distribution along the bunch compressor.Start-to-end beam dynamics simulations using the ASTRA code were performed to optimize the electron beam properties for generating super-radiant THz-FEL radiation.The operational parameters considered in the simulations comprise the alpha magnet gradient,linac RF phase,and quadrupole field strengths.The optimization results show that 10-16MeV femtosecond electron bunches with a low energy spread(~0.2%),small normalized emittance(~15πmm·mrad),and high peak current(165-247A)can be produced by the PCELL accelerator system at the optimal parameters.A THz-FEL with sub-microjoule pulse energies can thus be obtained at the optimized electron beam parameters.The physical and conceptual design of the THz-FEL beamline were completed based on the beam dynamics simulation results.The construction and installation of this beamline are currently underway and expected to be completed by mid-2024.The commissioning of the beamline will then commence. 展开更多
关键词 THz radiation THz free-electron laser Super-radiant free-electron laser Pre-bunched free-electron laser Beam dynamic simulation Femtosecond electron bunches
在线阅读 下载PDF
Compact RF linear accelerator for electron beam irradiation applications at PBP-CMU Electron Linac Laboratory
8
作者 Monchai Jitvisate Pittaya Apiwattanakul +3 位作者 Noppadol Kangrang Jatuporn Saisut Chitrlada Thongbai Sakhorn Rimjaem 《Nuclear Science and Techniques》 2025年第4期45-58,共14页
A 4 MeV RF linear accelerator for electron beam irradiation applications has been developed at the PBP-CMU Electron Linac Laboratory,Thailand.The system has been reengineered using a decommissioned medical linear acce... A 4 MeV RF linear accelerator for electron beam irradiation applications has been developed at the PBP-CMU Electron Linac Laboratory,Thailand.The system has been reengineered using a decommissioned medical linear accelerator.The main components include a thermionic DC electron gun,an RF linear accelerator,a beam diagnostic chamber,and a beam exit window for electron beam irradiation.Therefore,reengineering must be performed based on the characteristics of the electron beam and its dynamics throughout the system.In this study,the electron beam current density emitted from the cathode was calculated based on the thermionic emission theory,and the result was used to produce the electron beam distribution in the gun using CST Studio Suite^(■)software.The properties of the electron beam and its acceleration in the linear accelerator and downstream diagnostic section were studied using the ASTRA electron beam dynamics simulation code,with the aim of producing an electron beam with an average energy of 4 MeV at the linear accelerator exit.The transverse beam profile and electron deposition dose in the ambient environment were calculated using Geant4 Monte Carlo simulation software to estimate the beam performance for the irradiation experiments.The parameters studied can be used as guidelines for machine operation and future experimental plans. 展开更多
关键词 Thermionic electron gun RF linear accelerator Electron dynamics simulation Monte Carlo simulation Electron beam irradiation Electron beam processing Deposition dose
在线阅读 下载PDF
Cryopreservation of bovine sperm causes single‑strand DNA breaks that are localized in the toroidal regions of chromatin
9
作者 Jordi Ribas‑Maynou Rodrigo Muiño +1 位作者 Carolina Tamargo Marc Yeste 《Journal of Animal Science and Biotechnology》 2025年第1期92-106,共15页
Background Sperm cryopreservation is widely used in the cattle industry,as it allows for disassociating the localiza-tion of sires and the collection of semen from the timing of artificial insemination.While freeze-th... Background Sperm cryopreservation is widely used in the cattle industry,as it allows for disassociating the localiza-tion of sires and the collection of semen from the timing of artificial insemination.While freeze-thawing is known to impair sperm DNA integrity,whether the damage induced consists of single-(SSB)or double-strand breaks(DSB)has not been determined.In addition,no previous study has addressed if DNA breaks preferentially reside in specific genome regions such as those forming the toroid linker regions,or are rather spread throughout the regions linked to protamines.The main aim of the present work,therefore,was to elucidate the type and localization of the DNA damage generated by cryopreservation and to evaluate its impact on artificial insemination outcomes in cattle.Results The incidence of SSB and DSB was evaluated in 12 ejaculates before and after cryopreservation with the Comet assay,and the localization of the DNA breaks was assessed using pulsed-field gel electrophoresis(PFGE).Before cryopreservation,the incidence of SSB was 10.99%±4.62%and involved 20.56%±3.04%of sperm cells,whereas these figures significantly(P<0.0001)increased up to 34.11%±3.48%and 53.36%±11.00%in frozen-thawed sperm.In contrast,no significant differences in the incidence of DSB were observed(P>0.990)before and after cryopreservation(before:incidence of 13.91%±1.75%of sperm DNA affecting 56.04%±12.49%of sperm cells;after:incidence of 13.55%±1.55%of sperm DNA involving 53.36%±11.00%of sperm cells).Moreover,PFGE revealed that the percentage of sperm DNA fragments whose length was shorter than a toroid(<31.5 kb)was greater(P<0.0001)after(27.00%±4.26%)than before freeze-thawing(15.57%±4.53%).These differences indicated that the DNA breaks induced by cryopreservation affect the regions condensed in protamines,which are structured in toroids.On the other hand,in vivo fertility rates were associated to the incidence of SSB and DSB in frozen-thawed sperm(P=0.032 and P=0.005),but not with the size of the DNA fragments resulting from these breaks(P>0.05).Conclusion Cryopreservation of bovine sperm generates single-strand DNA breaks,which are mainly located in protamine-condensed toroidal regions.The incidence of DNA breaks in cryopreserved sperm has an impact on cat-tle fertility,regardless of the size of generated fragments. 展开更多
关键词 Cattle DNA damage Fertility SPERM Toroid linker regions
在线阅读 下载PDF
湘西北慈利大庸地区上震旦统—下寒武统沉积特征及层序地层划分 被引量:4
10
作者 李忠雄 王剑 +1 位作者 段太忠 高永华 《沉积与特提斯地质》 CAS CSCD 2003年第4期27-33,共7页
通过对各类层序界面的识别,以沉积特征、副层序和体系域与结构转换面等层序分析,进行露头层序地层学研究,将湘西北慈利 大庸地区台缘斜坡相区上震旦统—下寒武统划分为11个Ⅲ级层序,其中上震旦统7个、下寒武统4个,主要是Ⅱ型层序。在区... 通过对各类层序界面的识别,以沉积特征、副层序和体系域与结构转换面等层序分析,进行露头层序地层学研究,将湘西北慈利 大庸地区台缘斜坡相区上震旦统—下寒武统划分为11个Ⅲ级层序,其中上震旦统7个、下寒武统4个,主要是Ⅱ型层序。在区域层序地层对比、分析的基础上初步讨论了露头层序地层分析中存在的问题。 展开更多
关键词 上震旦统—下寒武统 沉积特征 层序地层划分 慈利-大庸地区 湘西北
在线阅读 下载PDF
CIPK9: a calcium sensor-interacting protein kinase required for low-potassium tolerance in Arabidopsis 被引量:23
11
作者 Girdhar K Pandey Yong Hwa Cheongx +3 位作者 Beom-Gi Kim John J Grant Legong Li Sheng Luan 《Cell Research》 SCIE CAS CSCD 2007年第5期411-421,共11页
Potassium is one of the major macro-nutrients essential for a number of cellular processes in plants. Low potassium level in the soil represents a limiting factor for crop production. Recent studies have identified po... Potassium is one of the major macro-nutrients essential for a number of cellular processes in plants. Low potassium level in the soil represents a limiting factor for crop production. Recent studies have identified potassium transporters that are involved in potassium acquisition, and some of them are critical for potassium nutrition under low potassium conditions. However, little is understood on the molecular components involved in low potassium signaling and responses. We report here the identification ofa calcineurin B-like protein-interacting protein kinase (CIPK9) as a critical regulator of low potassium response in ,Arabidopsis. The CIPK9 gene was responsive to abiotic stress conditions, and its transcript was inducible in both roots and shoots by potassium deprivation. Disruption of CIPK9 function rendered the mutant plants hypersensitive to low potassium media. Further analysis indicated that K^+ uptake and content were not affected in the mutant plants, implying CIPK9 in the regulation of potassium utilization or sensing processes. 展开更多
关键词 CALCIUM calcineurin-B like protein protein kinase potassium nutrition signal transduction
在线阅读 下载PDF
REE Tetrad Effects in Rare-metal Granites 被引量:9
12
作者 赵振华 AKIMASA MASUDA M.B.SHABANI 《Chinese Journal Of Geochemistry》 EI CAS 1993年第3期206-219,共14页
Described in this paper are the characteristics of tetrad effects of REE in rare-metal granites.Based on the analytical data and experimental geochemical data available,it is pointed out that the tetrad effects of REE... Described in this paper are the characteristics of tetrad effects of REE in rare-metal granites.Based on the analytical data and experimental geochemical data available,it is pointed out that the tetrad effects of REE in the granites are produced in the metal-fluid system.Intense fractional crystallization of granitic melt(containing REE accessary minerals)and its interaction with volatile-rich(F,Cl)fluid are the major factors leading to the tetrad effects of REE.From this,this paper presents a composite genetic model for high-degree fractional crystallization-volatile-rich fluid metasomatism of rare-metal granites.With the model,quantitative calculations have been made.Meanwhile,it is pointed out that the tetrad effects of REE can be used as an important indicator to distinguish mineralized granites from barren ones. 展开更多
关键词 花岗岩 稀土元素 成因
在线阅读 下载PDF
Relationship between Traditional Chinese Medicine Syndrome Type and Coronary Arteriography of Acute Coronary Syndrome 被引量:30
13
作者 王显 林钟香 +2 位作者 葛均波 张振贤 沈琳 《Chinese Journal of Integrated Traditional and Western Medicine》 2003年第2期116-119,共4页
Objective: To explore the relationship of Traditional Chinese Medicine (TCM) Syndrome type and coronary arteriography (CAG) with respect to the number and degree of stenosed branches of coronary artery (CA) and ACC/AH... Objective: To explore the relationship of Traditional Chinese Medicine (TCM) Syndrome type and coronary arteriography (CAG) with respect to the number and degree of stenosed branches of coronary artery (CA) and ACC/AHA stage of acute coronary syndrome (ACS), to provide an objective evidence for TCM Syndrome typing on ACS Methods: Ninety patients of ACS with their TCM Syndrome typing and CAG successfully conducted were enrolled in this study. They were classified into 3 Syndrome types, the blood stasis type (type I ), the phlegm stagnant with blood stasis type (type II ),and the endogenous collateral Wind type (type III) The scores of the number and severity of the stenosis branch of CA and ACC/AHA lesion stage in different Syndrome types were calculated respectively and analysed statistically by Ridit analysis. Results: The number of stenosed branches increased gradually with the Syndrome type changing from I -II-III, compared the type III with the other two types(P<0. 01). The severity of stenosis in type I and II were similar, but that of Type III, much aggravated was significantly different from that in the former two (P<0. 01) . The ACC/AHA stage of coronary lesion tended to be more complex as the Syndrome type changed, patients of TCM type I and II had mostly lesion of stage A or Bl , while lesion in majority of patients of type III belonged to stage B2 or C, comparison between the three types showed significant difference (P<0.01). Conclusion: Most ACS patients of TCM Syndrome type III with tri-branch, severe stenosed coronary arteries, belong to the complex ACC/AHA stage of B2 and C. 展开更多
关键词 coronary heart disease acute coronary syndrome TCM Syndrome type coronary arteriogrphy
暂未订购
Interannual and Decadal Variability of Landfalling Tropical Cyclones in the Southeast Coastal States of the United States 被引量:4
14
作者 Li'an Xie Leonard J. Pietrafesa Kejian Wu 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2002年第4期677-686,共10页
The interannual variability of the Atlantic tropical cyclone (TC) frequency is well known. Separately, recent studies have also suggested that a much longer, multidecadal (40-60 year) trend might be emerging from the ... The interannual variability of the Atlantic tropical cyclone (TC) frequency is well known. Separately, recent studies have also suggested that a much longer, multidecadal (40-60 year) trend might be emerging from the recent increase in Atlantic TC activity. However, the overall structure of the intrinsic frequencies (or temporal modes) of Atlantic TC activity is not yet known. The focus of this study is to systematically an-alyze the intrinsic frequencies of Atlantic TC activity using hurricane and tropical storm landfall data collec-ted along the southeast coast(SEC) of the United States, Based on an Empirical Mode Decomposition (EMD) analysis of the frequency of landfall TCs along the SEC from 1887-1999, we have found that Atlantic TC activity has four primary, temporal modes. The interannual and multidecadal modes reported in the published literature are two such modes. After identifying all primary modes, the relative importance of each mode and its physical cause can be analyzed. For example, the most energetic mode is the interannual mode (2-7 year period). This mode is known to be associated with the 2-7 year El Nino/ La Ni na cycle. The average number of annual landfalling TCs along (he SEC decreased by 24% during El Nino years, but did not show significant increase during weak and moderate La Nina years. However, intense La Nina years were generally associated with more than average landfalling TCs along the SEC. The effects of El Nino and La Nina also became more significant when only hurricanes were considered. The significance of the effects of El Nino and La Nina on landfalling TCs and hurricanes in different US southeast coastal states showed significant differences. 展开更多
关键词 tropical cyclone empirical mode decomposition El Nino decadal variability
在线阅读 下载PDF
Re–Os dating of molybdenite and in-situ Pb isotopes of sulfides from the Lamo Zn–Cu deposit in the Dachang tin-polymetallic ore field, Guangxi, China 被引量:12
15
作者 Hai Zhao Wenchao Su +5 位作者 Peng Xie Nengping Shen Jiali Cai Ming Luo Jie Li Zhian Bao 《Acta Geochimica》 EI CAS CSCD 2018年第3期384-394,共11页
The Dachang tin-polymetallic district, Guangxi,China, is one of the largest tin ore fields in the world. Both cassiterite-sulfide and Zn–Cu skarn mineralization are hosted in the Mid-Upper Devonian carbonate-rich sed... The Dachang tin-polymetallic district, Guangxi,China, is one of the largest tin ore fields in the world. Both cassiterite-sulfide and Zn–Cu skarn mineralization are hosted in the Mid-Upper Devonian carbonate-rich sediments adjacent to the underlying Cretaceous Longxianggai granite(91–97 Ma). The Lamo Zn–Cu deposit is a typical skarn deposit in the district and occurs at the contact zone between the Upper Devonian limestone and the granite.The ore minerals mainly consist of sphalerite, arsenopyrite,pyrrhotite, galena, chalcopyrite, and minor molybdenite.However, the age of mineralization and source of the metals are not well constrained. In this study, we use the molybdenite Re–Os dating method and in-situ Pb isotopes of sulfides from the Lamo deposit for the first time in order to directly determine the age of mineralization and the tracing source of metals. Six molybdenite samples yielded a more accurate Re–Os isochron age of 90.0 ± 1.1 Ma(MSWD = 0.72), which is much younger than the reported garnet Sm–Nd isochron age of 95 ± 11 Ma and quartz fluid inclusions Rb–Sr isochron age of 99 ± 6 Ma. This age is also interpreted as the age of Zn–Cu skarn mineralization in the Dachang district. Further, in this study we found that in-situ Pb isotopes of sulfides from the Lamo deposit and feldspars in the district's biotite granite and granitic porphyry dikes have a narrow range and an overlap of Pb isotopic compositions(^(206) Pb/^(204) Pb =18.417–18.594,^(207) Pb/^(204) Pb = 15.641–15.746, and^(208) Pb/^(204) Pb = 38.791–39.073), suggesting that the metals were mainly sourced from Cretaceous granitic magma. 展开更多
关键词 MOLYBDENITE Re-Os DATING IN-SITU leadisotopes SKARN DEPOSIT - DACHANG
在线阅读 下载PDF
Sexual selection and magic traits in speciation with gene flow 被引量:5
16
作者 Maria R. SERVEDIO Michael KOPP 《Current Zoology》 SCIE CAS CSCD 2012年第3期510-516,共7页
The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept ... The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits (i.e., traits involved in both reproductive isolation and ecological divergence). Both magic traits and other, "non-magic", traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the ex- tent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to in- hibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more ef- fective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 (3): 510-516, 2012]. 展开更多
关键词 Assortative mating Divergent selection Ecological selection Mating cues Non-random mating PREFERENCES
原文传递
NECK LEAF 1, a GATA type transcription factor, modulates organogenesis by regulating the expression of multiple regulatory genes during reproductive development in rice 被引量:7
17
作者 Liping Wang Hengfu Yin +4 位作者 Qian Qian Jun Yang Chaofeng Huang Xiaohe Hu Da Luo 《Cell Research》 SCIE CAS CSCD 2009年第5期598-611,共14页
In the monocot rice species Oryza sativa L., one of the most striking morphological processes during reproductive development is the concurrence of panicle development with the sequential elongation of upper internod... In the monocot rice species Oryza sativa L., one of the most striking morphological processes during reproductive development is the concurrence of panicle development with the sequential elongation of upper internodes (UPIs). To elucidate the underlying molecular mechanisms, we cloned the rice gene NECK LEAF 1 (NL1), which when mutated results in delays in flowering time, smaller panicles with overgrown bracts and abnormal UPI elongation patterns. The NL1 gene encodes a GATA-type transcription factor with a single zinc finger domain, and its transcripts are de- tected predominantly in the bract primordia, which normally degenerate in the wild-type plants. Overexpression of NL1 in transgenic plants often gives rise to severe growth retardation, less vegetative phytomers and smaller leaves, suggesting that NL1 plays an important role in organ differentiation. A novel mutant allele of PLASTOCHRON1 (PLAD, a gene known to play a key role in regulating leaf initiation, was identified in this study. Genetic analysis demonstrated an interaction between nil and plal, with NL1 acting upstream of PLA1. The expression level and spatial pattern of PLA1 were found to be altered in the nil mutant. Furthermore, the expression of two regulators of flowering, Hd3a and OsMADS1, was also affected in the nil mutant. On the basis of these findings, we propose that NL1 is an intrinsic factor that modulates and coordinates organogenesis through regulating the expression of PLA1 and other regulatory genes during reproductive development in rice. 展开更多
关键词 elongation of upper internodes ORGANOGENESIS panicle development phase transition NECK LEAF 1 GATA- like transcription factor
在线阅读 下载PDF
Induction of ischemic tolerance as a promising treatment against diabetic retinopathy 被引量:3
18
作者 Ruth E.Rosenstein Diego C.Fernandez 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第17期1581-1584,共4页
Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic reti- nopathy have foc... Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic reti- nopathy have focused either on highly specific therapeutic approaches for pharmacologic targets or using genetic approaches to change expression of certain enzymes. However, it might be wise to choose innovative treatment modalities that act by multiple potential mechanisms. The resis- tance to ischemic injury, or ischemic tolerance, can be transiently induced by prior exposure to a non-injurious preconditioning stimulus. A complete functional and histologic protection against retinal ischemic damage can be achieved by previous preconditioning with non-damaging isch- emia. In this review, we will discuss evidence that supports that ischemic conditioning could help avert the dreaded consequences that results from retinal diabetic damage. 展开更多
关键词 diabetic retinopathy ischemic tolerance RETINA ischemic injury ischemic conditioning
暂未订购
Dissolved organic matter tracers reveal contrasting characteristics across high arsenic aquifers in Cambodia:A fluorescence spectroscopy study 被引量:3
19
作者 Laura A. Richards Dan J. Lapworth +5 位作者 Daniel Magnone Daren C. Gooddy Lee Chambers Peter J. Williams Bart E. van Dongen David A. Polya 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第5期1653-1667,共15页
Organic matter in the environment is involved in many biogeochemical processes,including the mobilization of geogenic trace elements,such as arsenic,into groundwater.In this paper we present the use of fluorescence sp... Organic matter in the environment is involved in many biogeochemical processes,including the mobilization of geogenic trace elements,such as arsenic,into groundwater.In this paper we present the use of fluorescence spectroscopy to characterize the dissolved organic matter (DOM) pool in heavily arsenicaffected groundwaters in Kandal Province,Cambodia.The fluorescence DOM (fDOM) characteristics between contrasting field areas of differing dominant lithologies were compared and linked to other hydrogeochemical parameters,including arsenic and dissolved methane as well as selected sedimentary characteristics.Absorbance-corrected fluorescence indices were used to characterize depth profiles and compare field areas.Groundwater fDOM was generally dominated by terrestrial humic and fulvic-like components,with relatively small contributions from microbially-derived,tryptophan-like components.Groundwater fDOM from sand-dominated sequences typically contained lower tryptophan-like,lower fulvic-like and lower humic-like components,was less bioavailable,and had higher humification index than clay-dominated sequences.Methane concentrations were strongly correlated with fDOM bioavailability as well as with tryptophan-like components,suggesting that groundwater methane in these arsenic-prone aquifers is likely of biogenic origin.A comparison of fDOM tracers with sedimentary OM tracers is consistent with the hypothesis that external,surface-derived contributions to the aqueous DOM pool are an important control on groundwater hydrogeochemistry. 展开更多
关键词 ARSENIC Fluorescence spectroscopy Organic MATTER characterization Parallel factor analysis (PARAFAC) Groundwater quality
在线阅读 下载PDF
Fracture gradient prediction:an overview and an improved method 被引量:3
20
作者 Jincai Zhang Shang-Xian Yin 《Petroleum Science》 SCIE CAS CSCD 2017年第4期720-730,共11页
The fracture gradient is a critical parameter for drilling mud weight design in the energy industry. A new method in fracture gradient prediction is proposed based on analyzing worldwide leak-off test(LOT) data in off... The fracture gradient is a critical parameter for drilling mud weight design in the energy industry. A new method in fracture gradient prediction is proposed based on analyzing worldwide leak-off test(LOT) data in offshore drilling. Current fracture gradient prediction methods are also reviewed and compared to the proposed method. We analyze more than 200 LOT data in several offshore petroleum basins and find that the fracture gradient depends not only on the overburden stress and pore pressure, but also on the depth. The data indicate that the effective stress coefficient is higher at a shallower depth than that at a deeper depth in the shale formations. Based on this finding,a depth-dependent effective stress coefficient is proposed and applied for fracture gradient prediction. In some petroleum basins, many wells need to be drilled through long sections of salt formations to reach hydrocarbon reservoirs.The fracture gradient in salt formations is very different from that in other sedimentary rocks. Leak-off test data in the salt formations are investigated, and a fracture gradient prediction method is proposed. Case applications are examined to compare different fracture gradient methods and validate the proposed methods. The reasons why the LOT value is higher than its overburden gradient are also explained. 展开更多
关键词 Fracture gradient prediction Leak-off test Breakdown pressure Mud loss Fracture gradient in salt
原文传递
上一页 1 2 35 下一页 到第
使用帮助 返回顶部