期刊文献+
共找到7,953篇文章
< 1 2 250 >
每页显示 20 50 100
Assessing Stable/Unstable Effects of Socio-economic Development and Climate Change on Ecosystem Service Interactions in the Hanshui River Basin,China
1
作者 ZHANG Bowen liU Dianfeng +2 位作者 ZHENG liang WANG Ying li na 《Chinese Geographical Science》 2025年第5期1201-1216,共16页
Interactions among ecosystem services(ESs)are spatially heterogeneous,shaped by both stable(unidirectional)and unstable(context-dependent)influences of socio-economic development and climate change.These complexities ... Interactions among ecosystem services(ESs)are spatially heterogeneous,shaped by both stable(unidirectional)and unstable(context-dependent)influences of socio-economic development and climate change.These complexities pose significant challenges for spatially adaptive ecosystem management.Ecosystem service bundles(ESBs),as recurring combinations of ESs,offer a valuable framework to capture such interactions.Here,we proposed an integrated analytical framework that combines K-means clustering,the geographical detector(GD)model,and geographically and temporally weighted regression(GTWR)models to evaluate how socio-economic and climatic drivers influence ESBs across space and time.Using Hanshui River Basin(HRB)in central China as a case study,we quantified ES dynamics from 2000 to 2020,identified ESBs and stable and unstable effects of multiple drivers.The results showed that carbon sequestration(CS),water yield(WY),and aesthetic landscape(AL)increased by 32.80%,9.00%,and 7.34%,respectively,while soil retention(SR)and food supply(FS)declined by 8.38%and 5.36%.Five distinct ESBs were identified,namely ecologically fragile bundle(EFB),agricultural production bundle(APB),water supply bundle(WSB),forest ecological bundle(FEB),and ecological conservation bundle(ECB).Among these,FEB expanded to more than 35.75%of the HRB,and APB exhibited the sharpest decline(-28.64%).Land use intensity(LUI)was the primary driver of the spatial heterogeneity of ESBs,while synergistic and nonlinear interactions among multiple factors increasingly amplified their effects over time.Notably,annual precipitation(AP)emerged as the only stable basin-scale driver,consistently enhancing ES performance,while gross domestic product(GDP)and normalized difference vegetation index(NDVI)had stable yet spatially differentiated effects across bundles.Our findings highlight the significance of distinguishing stable/unstable driver effects on ES dynamics to inform regionally adaptive ecosystem governance.The proposed framework provides valuable insights into ES interactions,identify spatial priorities,and support policy interventions that balance ecological conservation with socio-economic development. 展开更多
关键词 ecosystem services(ESs) ecosystem service bundles(ESBs) stable/unstable effects spatial heterogeneity targeted ecological management Hanshui River Basin(HRB) Chi
在线阅读 下载PDF
sRNA rli106在单核细胞增生李斯特菌环境应激及生物被膜形成中的调控作用研究 被引量:6
2
作者 郭蕴 季春辉 +5 位作者 王立霞 宁程程 李娜 孟庆玲 乔军 才学鹏 《中国预防兽医学报》 CAS CSCD 北大核心 2022年第3期277-283,共7页
单核细胞增生李斯特菌(LM)是一种重要的食源性病原菌,可适应不同的应激环境。为探究LM sRNA rli106基因的生物学功能,本研究以LM EGD-e为亲本株,通过PCR方法扩增sRNA rli106基因,并分析其分子特征;利用同源重组技术构建了LM-Δrli106基... 单核细胞增生李斯特菌(LM)是一种重要的食源性病原菌,可适应不同的应激环境。为探究LM sRNA rli106基因的生物学功能,本研究以LM EGD-e为亲本株,通过PCR方法扩增sRNA rli106基因,并分析其分子特征;利用同源重组技术构建了LM-Δrli106基因缺失株和CLM-Δrli106基因回补株,分析比较LM EGD-e、LM-Δrli106、CLM-Δrli106在不同应激环境中的适应能力、运动性以及生物被膜(BF)形成能力,并通过qRT-PCR检测BF生成相关基因gltB和gltC的相对转录水平。结果显示,sRNA rli106基因大小为225 bp,上游序列含有-10 box和-35 box启动子核心区域,有转录调节因子CpxR的结合位点。与LM EGD-e、CLM-Δrli106相比,LM-Δrli106在42℃、5%NaCl、8%NaCl、5 mmol/L H2O2的环境应激下的适应性显著减弱,运动性无明显差异,在不同时间段的BF形成能力显著降低。qRT-PCR检测结果显示,LM-Δrli106中gltB和gltC基因的相对转录水平均有所降低。本研究结果首次表明,rli106基因在环境适应性和BF形成中发挥重要的调控作用,但不参与细菌运动性,为揭示rli106基因在LM环境适应性和BF形成中的分子调控机制奠定基础。 展开更多
关键词 单核细胞增生李斯特菌 sRNA rli106 环境适应性 生物被膜
在线阅读 下载PDF
多参数MRI影像组学3D及2D特征预测Luminal型乳腺癌HER-2表达状态的研究
3
作者 尹阳 郭济韬 +4 位作者 李雯璐 张健 赵艳 李娜 杨志远 《西部医学》 2025年第4期608-614,619,共8页
目的探讨基于多参数磁共振成像(MRI)影像组学3D及2D特征在术前预测乳腺癌人表皮生长因子受体2(HER-2)不同表达状态的价值。方法回顾性分析2021年7月—2023年11月我院经病理证实为Luminal型乳腺癌的147例患者的MRI图像,将患者按7∶3的比... 目的探讨基于多参数磁共振成像(MRI)影像组学3D及2D特征在术前预测乳腺癌人表皮生长因子受体2(HER-2)不同表达状态的价值。方法回顾性分析2021年7月—2023年11月我院经病理证实为Luminal型乳腺癌的147例患者的MRI图像,将患者按7∶3的比例随机分为训练集和测试集[HER-2阳性与阴性(任务1)、低表达与0表达(任务2)、低表达和阳性与0表达(任务3)方面],从DWI、动态增强前蒙片(S0)、动态增强第3期(S3)图像中提取瘤内及瘤周的3D和2D影像组学特征,通过3种归一化方法、2种降维方法、4种特征选择方法、10种分类器进行多种流水线组合构建模型,通过受试者工作特征(ROC)曲线及曲线下的面积(AUC)评估模型的预测效能,选出3D和2D单参数(DWI、S0、S3)及多参数组合(S0+S3、S0+DWI、S3+DWI、S0+S3+DWI)的最佳模型,通过Delong检验比较不同模型间的差异。结果任务1中,3D和2D各模型在训练集AUC为0.777~0.832、0.708~0.882,测试集AUC为0.707~0.829、0.702~0.846;任务2中,3D和2D各模型在训练集AUC为0.779~0.870、0.751~0.863,测试集AUC为0.759~0.846、0.728~0.829;任务3中,3D和2D各模型在训练集AUC为0.781~0.891、0.740~0.866,测试集AUC为0.776~0.870、0.727~0.846;3个任务中3D与2D相同参数模型间比较均无明显统计学差异。结论基于多参数MRI影像组学模型能够较好地预测乳腺癌HER-2表达状态,基于瘤内及瘤周的3D和2D特征模型具有同等预测效能。 展开更多
关键词 影像组学 乳腺癌 人表皮生长因子受体2 磁共振成像
暂未订购
老年重症肺炎并发呼吸衰竭患者血清NAMPT、suPAR水平及其对预后的预测价值
4
作者 杨君莉 蒋艳敏 +2 位作者 李娜 韩晓楠 张颖 《检验医学与临床》 2025年第18期2458-2463,共6页
目的探讨老年重症肺炎(SP)并发呼吸衰竭(RF)患者血清烟酰胺磷酸核糖基转移酶(NAMPT)、可溶性尿激酶型纤溶酶原激活物受体(suPAR)对预后(入院30 d死亡)的预测价值。方法选取2020年12月至2023年12月在该院接受治疗的164例老年SP并发RF患... 目的探讨老年重症肺炎(SP)并发呼吸衰竭(RF)患者血清烟酰胺磷酸核糖基转移酶(NAMPT)、可溶性尿激酶型纤溶酶原激活物受体(suPAR)对预后(入院30 d死亡)的预测价值。方法选取2020年12月至2023年12月在该院接受治疗的164例老年SP并发RF患者作为研究组,同时选取同期该院体检健康者164例作为对照组。根据急性生理学与慢性健康状况评价Ⅱ(APACHEⅡ)评分将研究组分为轻危组、中危组、重危组。自入院开始随访30 d,根据生存状态将研究组分为死亡组、生存组。采用酶联免疫吸附试验(ELISA)测定血清NAMPT、suPAR水平。采用Spearman相关分析老年SP并发RF患者血清NAMPT、suPAR水平与疾病严重程度的相关性。采用多因素Logistic回归分析老年SP并发RF患者入院30 d死亡的影响因素。绘制受试者工作特征(ROC)曲线分析血清NAMPT、suPAR对老年SP并发RF患者入院30 d死亡的预测价值。结果与对照组相比,研究组血清NAMPT、suPAR水平升高(P<0.05)。与轻危组相比,中危组、重危组NAMPT、suPAR水平升高(P<0.05),与中危组相比,重危组NAMPT、suPAR水平升高(P<0.05)。SP并发RF患者血清NAMPT、suPAR水平与疾病严重程度呈正相关性(r_(s)=0.428、0.313,均P<0.05)。与生存组相比,死亡组患者NAMPT、suPAR水平显著升高(P<0.05)。生存组和死亡组机械通气占比、APACHEⅡ评分比较,差异均有统计学意义(P<0.05)。多因素Logistic回归分析显示,NAMPT、suPAR、机械通气是SP并发RF患者入院30 d死亡的影响因素(P<0.05)。血清NAMPT、suPAR联合预测SP并发RF患者入院30 d死亡的曲线下面积(AUC)大于NAMPT、suPAR单独预测的AUC(Z_(二者联合vs.NAMPT)=2.176、P=0.030,Z_(二者联合vs.suPAR)=2.398、P=0.017)。结论老年SP并发RF患者血清NAMPT、suPAR水平显著升高,二者联合检测可提高对入院30 d死亡的预测价值。 展开更多
关键词 重症肺炎 呼吸衰竭 烟酰胺磷酸核糖基转移酶 可溶性尿激酶型纤溶酶原激活物受体 老年
暂未订购
Quercus yangyiensis sp. nov. from the Late Pliocene of Baoshan, Yunnan and Its Paleoclimatic Significance 被引量:8
5
作者 HE Yuli li na +5 位作者 WANG Zixi WANG Haofei YANG Guolin XIAO liang WU Jingyu SUN Bainian 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第3期738-747,共10页
A new Quercus (Fagaceae) morphospecies is described based on well-preserved fossil leaves.The fossils were collected from Yangyi Formation of the Upper Pliocene at the Yangyi coalmine,Baoshan,western Yunnan,China.De... A new Quercus (Fagaceae) morphospecies is described based on well-preserved fossil leaves.The fossils were collected from Yangyi Formation of the Upper Pliocene at the Yangyi coalmine,Baoshan,western Yunnan,China.Details of the microstructure of mesophyll tissue are preserved because lithification of the fossils was not complete.The fossil laminas possess typical characteristics of Quercus sect.Heterobalanus:quite thick and coriaceous cuticle; secondary veins bifurcating near the margin in the middle and top of the leaf; and upper epidermis with adaxial hypodermis.Based on a detailed morphological and anatomical comparison with all living and fossil species of Quercus sect.Heterobalanus,the fossil leaves prove to be different in their sparse and garland-shaped multicellular trichomes on the lower epidermis,and so it is described as a new species Quercus yangyiensis He,Li et Sun sp.nov.The much sparser trichomes of our fossils compare well with those of living Quercus sect.Heterobalanus and indicate a more humid climate during the deposition of the Yangyi Formation in the Late Pliocene. 展开更多
关键词 PALEOBOTANY fossil leaf cuticle QUERCUS PALEOCLIMATE PLIOCENE YUNNAN
在线阅读 下载PDF
Geochemical characteristics and their significances of rare-earth elements in deep-water well core at the Lingnan Low Uplift Area of the Qiongdongnan Basin 被引量:7
6
作者 SUN Zhipeng ZHAI Shikui +6 位作者 XIU Chun liU Xinyu ZONG Tong LUO Wei liU Xiaofeng CHEN Kui li na 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2014年第12期81-95,共15页
A geochemical analysis of rare-earth elements (REEs) in 97 samples collected from the core of deep-water Well LS-A located at the Lingnan Low Uplift Area of the Qiongdongnan Basin is conducted, with the pur-pose of ... A geochemical analysis of rare-earth elements (REEs) in 97 samples collected from the core of deep-water Well LS-A located at the Lingnan Low Uplift Area of the Qiongdongnan Basin is conducted, with the pur-pose of revealing the changes of sedimentary source and environment in the study region since Oligocene and evaluating the response of geochemical characteristics of REEs to the tectonic evolution. In the core samples, both∑REE and∑LREE (LREE is short for light-group REEs) fluctuate in a relatively wide range, while∑HREE (HREE is short for heavy-group REEs) maintains a relatively stable level. With the stratigraphic chronology becoming newer, both∑REE and∑LREE show a gradually rising trend overall. The∑REE of the core is relatively high from the bottom of Yacheng Formation (at a well depth of 4 207 m) to the top of Ledong Formation, and the REEs show partitioning characteristics of the enrichment of LREE, the stable content of HREE, and the negative anomaly of Eu to varying degrees. Overall the geochemical characteristics of REEs are relatively approximate to those of China's neritic sediments and loess, with significant "continental ori-entation". The∑REE of the core is relatively low in the lower part of Yacheng Formation (at a well depth of 4 207-4 330 m), as shown by the REEs partitioning characteristics of the depletion of LREE, the relative enrich-ment of HREE, and the positive anomaly of Eu; the geochemical characteristics of REEs are approximate to those of oceanic crust and basalt overall, indicating that the provenance is primarily composed of volcanic eruption matters. As shown by the analyses based on sequence stratigraphy and mineralogy, the provenance in study region in the early Oligocene mainly resulted from the volcanic materials of the peripheral uplift ar-eas; the continental margin materials from the north contributed only insignificantly; the provenance devel-oped to a certain extent in the late Oligocene. Since the Miocene, the provenance has ceaselessly expanded from proximal to distal realm, embodying a characteristic of multi-source sedimentation. In the core strata with 31.5, 28.4, 25.5, 23, and 16 Ma from today, the geochemical parameters of REEs and Th/Sc ratio have significant saltation, embodying the tectonic movement events in the evolution of the Qiongdongnan Basin. In the tectonic evolution history of the South China Sea, the South China Sea Movement (34-25 Ma BP, early expansion of the South China Sea), Baiyun Movement (23 Ma BP), late expansion movement (23.5-16.5 Ma BP), expansion-settlement transition, and other important events are all clearly recorded by the geochemi-cal characteristics of REEs in the core. 展开更多
关键词 Qiongdongnan Basin deep-water well core rare-earth elements sedimentary source andenvironment response to tectonic movement
在线阅读 下载PDF
Recovery of the Erosion Thickness and Characterization of the Paleogeomorphology in the Southern Lishui Sag, East China Sea Shelf Basin 被引量:4
7
作者 li na ZHANG Jinliang +4 位作者 SHEN Wenlong liU Yang liU Huaishan WANG Jinkai XIE Jun 《Journal of Ocean University of China》 SCIE CAS CSCD 2020年第2期320-330,共11页
The restoration of the denudation thickness is the basis for quantitatively analyzing the basin burial history,thermal evolution history and hydrocarbon accumulation conditions.The well data is not sufficient to do th... The restoration of the denudation thickness is the basis for quantitatively analyzing the basin burial history,thermal evolution history and hydrocarbon accumulation conditions.The well data is not sufficient to do this in the southern Lishui Sag with only 5 wells,so the new,high-quality three-dimensional(3D)seismic data is essential.The methods employed to determine the eroded thicknesses of key unconformities in the study area are the mudstone acoustic time difference(AC)method,vitrinite reflectance(Ro%)method and stratigraphic trend comparison method.On the basis of the structural evolution,the restoration of the paleogeomorphology is carried out.The results show that the Wenzhou formation(E2 w)in the entire study area has been all denuded.The denudation thickness is in the range of 0–550 m,and decreases gradually from west,thicker than 200 m,to east.The erosion of the upper Lingfeng formation(E1l)are mainly occurred in the N-P-1 structural trap(N-P-1),the N-P-2 structural trap(N-P-2)and the N-P-3 structural trap(N-P-3).Among them,the eroded area in N-P-1(near well S-1)and N-P-2 is 200–230 km^2,and the denudation thickness is 0–600 m,which increases from south to north,even up to 200–400 m in the region around well S-1.In N-P-3,the extent of denudation is 30–50 km^2,and the denudation thickness is 0–400 m.In the early stage of the upper E1 l,one north-south strike slip fault began to develop in the southern study area.Affected by this fault,the southern Lingfeng bulge was offset,forming a gorge,and the eastern and western sides of the concave belt connected to each other.On the basis of the paleo-geomorphological characteristics,it is shown that the sedimentary center of the west subsag began to migrate to the south. 展开更多
关键词 Oil and gas denudation thickness paleogeomorphology stratigraphic trend Lishui Sag
在线阅读 下载PDF
Intensity Allocation Criteria of Carbon Emissions Permits and Regional Economic Development in China——Based on a 30-Province/Autonomous Region Computable General Equilibrium Model 被引量:4
8
作者 YUAN Yong-na SHI Min-Jun +1 位作者 li na ZHOU Sheng-Lu 《Advances in Climate Change Research》 SCIE 2012年第3期154-162,共9页
The intensity allocation criteria of carbon emissions permits and its influence on China's regional development are analyzed through the 30-province/autonomous region computable general equilibrium(CGE)model.Simul... The intensity allocation criteria of carbon emissions permits and its influence on China's regional development are analyzed through the 30-province/autonomous region computable general equilibrium(CGE)model.Simulation results show that:industrial intensity criteria without taking regional economic development into account deepen the unbalance of regional economic development;regional intensity criteria without taking industrial properties into account exert little negative impact on regional harmonious development,but relatively high negative influence on high-carbon emission industries.The two-step allocation scheme that the central government allocates emissions permits to provincial governments based on regional economic development and then provincial governments allocate emissions permits to emission resources or entities based on industrial properties is a feasible and operable choice. 展开更多
关键词 carbon emissions permits intensity allocation criteria regional balanced development computable general equilibrium model
在线阅读 下载PDF
Inbreeding Depression on Growth and Survival of Full-Sib Family of Manila Clam(Ruditapes philippinarum) 被引量:2
9
作者 HUO Zhongming li na +3 位作者 ZHANG Xuekai li Ying YAN Xiwu YANG Feng 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第1期145-150,共6页
In present study, the inbreeding depression(ID) of growth and survival of Manila clam(Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families(A_2, B_2, C_2, D_2, E_2, F_2, G_2, H_... In present study, the inbreeding depression(ID) of growth and survival of Manila clam(Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families(A_2, B_2, C_2, D_2, E_2, F_2, G_2, H_2 and I_2) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae(straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group(CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A_2, B_2, C_2, and D_2, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A_2 family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated(R =-0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam. 展开更多
关键词 Ruditapes philippinarum GROWTH SURVIVAL INBREEDING DEPRESSION
在线阅读 下载PDF
Construction of Saccharomyces cerevisiae Strain Stably Expressing a Fusion Protein Containing Ten Tandem Recombinant Human Glucagon-like Peptide-1 Analogues 被引量:2
10
作者 WU Zhi-qiang JIA nai-bing +2 位作者 li na MA Bai-cheng li Ming-gang 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第6期882-886,共5页
The recombinant Saccharomyces cerevisiae strain stably expressing recombinant human glucagon-like peptide-l(rhGLP-1) analogue, as a potential oral drug delivery system for diabetes type II treatment, was successfull... The recombinant Saccharomyces cerevisiae strain stably expressing recombinant human glucagon-like peptide-l(rhGLP-1) analogue, as a potential oral drug delivery system for diabetes type II treatment, was successfully constructed by the homologous recombination between chromosomal DNA and yeast and integrating vector pNK-GLP containing yeast ribosomal DNA fragments. The amount of rhGLP-I analogue fusion protein in transformant SG2 reached ca. 0.84 mg per gram of packed cells when SG2 was grown for 24 h in the YPD medium with a inoculum and medium ratio of 1:1. Oral administration of 5 g lyophilized SG2/kg to hyperglycemic rats decreased serum glucose from (24.8±1.40) to (21.2±1.36) mmol/L. 展开更多
关键词 Saccharomyces cerevisiae Yeast integrating vector Ribosomal DNA Recombinant human glucagon-likepeptide- 1 Hyperglycemic rat
在线阅读 下载PDF
基于Illumina MiSeq高通量测序技术分析高温大曲发酵过程中真菌群落结构演替规律 被引量:1
11
作者 李娜 崔梦君 +4 位作者 倪慧 田龙新 叶明波 郭壮 侯强川 《中国酿造》 北大核心 2025年第5期169-174,共6页
该研究利用Illumina Mi Seq测序技术研究高温大曲发酵过程中真菌群落的演替规律。α多样性分析结果表明,高温大曲发酵过程中真菌群落的丰富度和多样性均呈先上升后下降的趋势,在第二次翻曲时,发现物种数(369.16)和辛普森指数(0.75)均达... 该研究利用Illumina Mi Seq测序技术研究高温大曲发酵过程中真菌群落的演替规律。α多样性分析结果表明,高温大曲发酵过程中真菌群落的丰富度和多样性均呈先上升后下降的趋势,在第二次翻曲时,发现物种数(369.16)和辛普森指数(0.75)均达到最大,且极显著高于拆曲出库时(P<0.01);优势真菌属包括嗜热子囊菌属(Thermoascus)、嗜热真菌属(Thermomyces)、曲霉属(Aspergillus)、罗萨氏菌属(Rasamsonia)和丝衣霉菌属(Byssochlamys)。β多样性分析结果表明,高温大曲发酵过程中真菌群落结构发生了较大变化。线性判别分析效应值大小(LEfSe)分析结果表明,不同发酵阶段呈现出特征性优势菌,Phialosimplex、Thermoascus和Thermomyces可分别为第一次翻曲、第二次翻曲和拆曲出库阶段的生物标志物。相关性分析结果表明,真菌群落结构的变化可能与菌群间的互作关系密切相关。该研究结果为后续优化大曲发酵过程和提高产品品质奠定了基础。 展开更多
关键词 高温大曲 发酵过程 高通量测序技术 真菌群落结构 群落演替
在线阅读 下载PDF
Extraction of Basic Trends of Urban Expansion in China over Past 40 Years from Satellite Images 被引量:4
12
作者 WEN Qingke ZHANG Zengxiang +10 位作者 SHI lifeng ZHAO Xiaoli liU Fang XU Jinyong YI ling liU Bin WANG Xiao ZUO lijun HU Shunguang li na li Minmin 《Chinese Geographical Science》 SCIE CSCD 2016年第2期129-142,共14页
If urban sprawl is to be avoided in China in the next ten years, it is not only crucial to understand the overall history, current status, and future trends of urban expansion there, but also these differences, and th... If urban sprawl is to be avoided in China in the next ten years, it is not only crucial to understand the overall history, current status, and future trends of urban expansion there, but also these differences, and this is presently lacking. In this study, remotely sensed images with approximately 30 m spatial resolution were used to quantitatively assess the spatial and temporal patterns of urban expansion of 60 Chinese cities(1973–2013). Urban-expansion-process curves of the cities studied were drawn using annual expansion area as an indicator. Curve similarity analysis generated four basic process modes of urban expansion in China. These included cities that: 1) peaked around 2004 and then decelerated; 2) peaked around 2010 and then decelerated; 3) showed sustained acceleration, and 4) showed continued deceleration. Four basic process modes represented cities under different levels of development stage. Geographic location was found to be the most related characteristic to urban expansion process. Regional development policies at the national level in each region also showed highly temporal consistency with fluctuation characteristics of urban expansion process. Urban characteristic such as population size and administrative level were not found to be significantly related to urban expansion-process modes. Understanding the basic process-mode categories well is extremely important for future regional-balance planning and development of macroeconomic policies. 展开更多
关键词 urban expansion urbanization expansion-process mode long term urban development stage curve similarity urban characteristic
在线阅读 下载PDF
The institution efficiency of stock price limits: An experimental analysis on the two stocks market with continuous bid 被引量:2
13
作者 li Jian-biao JU Long +2 位作者 ZHANG Bin li na liU Xu-guang 《Journal of Modern Accounting and Auditing》 2008年第4期1-13,共13页
Price limits in product market have been discarded in classic microeconomics. However, price limits affect the trade behavior of the same agent, since agents in the stock market change their trade status frequently. D... Price limits in product market have been discarded in classic microeconomics. However, price limits affect the trade behavior of the same agent, since agents in the stock market change their trade status frequently. Due to the controversy on the institution effectiveness of the price limits in stock market, this paper design an experimental market with two stocks with continuous bid, in which we investigate the impact of the price limits on the stock market. The results show that the price limits moderate the price volatility within and between the trades periods, thus can stabilize stock price. In addition, price limits, when measured by traditional approach, restrain the fluidity of the market, reduce the volatility of transaction shares and maintain durative of fluidity. While volatility-based fluidity measurements show that the fluidity is enhanced significantly in stock market with price limits. 展开更多
关键词 price limits VOLATILITY FLUIDITY validity experimental markets
在线阅读 下载PDF
Comparative Study on Growing-finishing Performance and Meat Quality of Different Hybrid Combinations in Pigs 被引量:1
14
作者 liU li-gang ZHANG Shu-min +4 位作者 li Zhao-hua li na JIN Xin YU Yong-sheng ZHAO Xiao-dong 《Animal Husbandry and Feed Science》 CAS 2009年第8期4-5,13,共3页
[Objective] The aim of this study was to investigate the production performance of three pig cultivars through their fattening performance, carcass traits and meat quality for facilitating its application in practical... [Objective] The aim of this study was to investigate the production performance of three pig cultivars through their fattening performance, carcass traits and meat quality for facilitating its application in practical production. [ Method] Three pig cultivars were selected including Yesong ( F1 hybrid of pure-bred wild boar cross with songliao black sow as female parent) hybrid pigs, D × L × Y pigs from three-way cross and L x Y pigs from two-way cross. The test pigs in early period (before 60 kg) and late period (after 60 kg) were all fed with diets of the same nutritional level by free feeding and drinking water. The pre-test period was 3 d, while the test period was 120 d. Every 30 days, pigs with an empty stomach were weighed on morning, and when fattening to 120 d, five pigs with good growth and development in each cultivar were selected for slaughter to determine carcass traits and meat quality. [ Result] Under the same diets and feeding conditions, average daily gain and weight gain in the whole period of pigs from three-way cross were all significantly higher than those of pigs from two-way cross, and also extremely higher than those of Yesong pigs. There was no difference in dressed carcass percentage, backfat thickness and proportion of hind leg among three hybrid combinations. Lean meat percentage and eye muscle area of pigs from three-way cross and pigs from two-way cross were all significantly higher than those of Yesong pigs. Yesong pigs had relatively darker carnation, but marble vein (P〈0.05) and water loss rate (P〈0. 01 ) of Yesong pigs were relatively fewer than those of pigs from two-way cross and pigs from three-way cross. Shear force of Yesong pigs was significantly higher than that of pigs from two-way cross and pigs from three-way cross, [ Conclusion] Yesong hybrid pigs make full use of heterosis between wild pigs and Songliao black pigs for improvement of its meat quality, but some values of major economic traits in Yesong hybrid pigs is still lower than those in pigs from thrae-way cross and pigs from two-way cress. 展开更多
关键词 PIGS Hybrid combinations Growng-finishing performance Meat quality
在线阅读 下载PDF
猫杯状病毒VP1蛋白B细胞表位的串联表达及间接ELISA方法的建立
15
作者 王真真 汤傲星 +9 位作者 刘春草 李娜 林亮亮 宋若楠 贾楠楠 杜汉宇 朱杰 李传峰 刘光清 孟春春 《中国动物传染病学报》 北大核心 2025年第3期103-109,共7页
为建立一种检测猫杯状病毒抗体的间接ELISA方法,本试验将截短的猫杯状病毒VP1蛋白表达为重组蛋白纯化后作为包被抗原。采用棋盘式方法优化反应的最佳血清稀释度和抗原包被量,同时对间接ELISA方法的其他反应条件进行了比较。结果显示,抗... 为建立一种检测猫杯状病毒抗体的间接ELISA方法,本试验将截短的猫杯状病毒VP1蛋白表达为重组蛋白纯化后作为包被抗原。采用棋盘式方法优化反应的最佳血清稀释度和抗原包被量,同时对间接ELISA方法的其他反应条件进行了比较。结果显示,抗原包被量为2μg/mL,血清最佳稀释度为1∶1000,37℃作用1 h;二抗的最佳工作浓度为1∶10000;TMB底物显色液37℃避光显色反应15 min。特异性试验结果显示,同FPV和FHV阳性血清均无交叉反应。此方法对猫细小病毒阳性血清的敏感性为1∶40960;组内、组间变异系数均小于5%。与本实验室建立的包被全病毒的方法平行比较,显示其检测阴阳性血清的值高度一致。结果表明,建立的基于截短的猫杯状病毒VP1蛋白建立的间接ELISA方法非常适用于临床样本的检测,可为猫杯状病毒的防控工作提供技术支撑。 展开更多
关键词 猫杯状病毒 VP1蛋白 串联的B细胞表位 间接ELISA
在线阅读 下载PDF
嗜水气单胞菌非编码RNA的功能研究
16
作者 王嘉璐 蔡彤璇 +4 位作者 陈甜梦 李娜 刘瑶瑶 赵宝华 刘东 《天津师范大学学报(自然科学版)》 北大核心 2025年第1期13-21,共9页
为了探究原核生物嗜水气单胞菌(Aeromonas hydrophila)中非编码RNA(sRNA)的功能,以嗜水气单胞菌A.hydrophila ATCC 7966菌株为实验材料,采用转录组测序技术进行转录组学分析,预测得到非编码RNA,构建了sRNA基因缺失突变体(△sRNA),并对△... 为了探究原核生物嗜水气单胞菌(Aeromonas hydrophila)中非编码RNA(sRNA)的功能,以嗜水气单胞菌A.hydrophila ATCC 7966菌株为实验材料,采用转录组测序技术进行转录组学分析,预测得到非编码RNA,构建了sRNA基因缺失突变体(△sRNA),并对△sRNA的生理特性和致病性进行测定.结果显示:△sRNA菌株与野生型菌株的生长状况、运动能力和溶血现象基本一致,且在高渗环境下2种菌株受到的抑制程度相同;同野生型菌株相比,△sRNA菌株的生物被膜形成能力与蛋白酶活性均显著降低(P<0.01),且△sRNA菌株对青霉素和红霉素的敏感度增强;sRNA基因的缺失导致A.hydrophila的致病性降低. 展开更多
关键词 嗜水气单胞菌 转录组测序 非编码RNA 基因敲除 致病性
在线阅读 下载PDF
LINC00543在胃癌中的表达及其对癌细胞增殖、迁移及EMT的影响
17
作者 宋京岗 李懿诺 +7 位作者 张茗萱 胡曼辉 马笑伟 李朝洋 豆建 李娜 王文斌 李日恒 《现代肿瘤医学》 2025年第9期1483-1491,共9页
目的:检测胃癌组织和细胞MGC-803、AGS中LINC00543的表达水平,研究LINC00543对胃癌细胞增殖、迁移及上皮-间充质转化(epithelial-mesenchymal transition,EMT)过程的影响。方法:本研究通过GEO和GEPIA数据库,分析LINC00543在胃癌组织中... 目的:检测胃癌组织和细胞MGC-803、AGS中LINC00543的表达水平,研究LINC00543对胃癌细胞增殖、迁移及上皮-间充质转化(epithelial-mesenchymal transition,EMT)过程的影响。方法:本研究通过GEO和GEPIA数据库,分析LINC00543在胃癌组织中的表达情况;使用qRT-PCR检测胃癌细胞MGC-803、AGS及胃黏膜细胞GES-1中LINC00543的表达水平;Western Blot检测胃癌细胞与胃黏膜细胞中上皮细胞-间充质转化相关蛋白Vimentin、E-cadherin、N-cadherin的表达水平;分别转染fam标记的siRNA和对照序列于胃癌细胞MGC-803及AGS,构建沉默组胃癌细胞Si-LINC00543和阴性对照组NC,转染24 h后通过荧光显微镜和qRT-PCR检测转染效率;使用CCK-8和细胞划痕实验分别检测各组细胞的增殖和迁移能力;Western Blot检测转染后各组细胞Vimentin、E-cadherin、N-cadherin的表达水平。结果:GEO和GEPIA显示,LINC00543在胃癌组织中高表达(P<0.05);同样地,qRT-PCR显示,其在胃癌细胞MGC-803、AGS较GES-1细胞高表达(P<0.01);Western Blot显示,相对于胃黏膜细胞,胃癌细胞中E-cadherin低表达,N-cadherin、Vimentin高表达(P<0.05);荧光显微镜下,使用蓝光激发,转染成功的细胞呈现绿色,qRT-PCR显示,相对于NC组,敲低组细胞的LINC00543表达量降低(P<0.05);CCK-8显示,相较于NC组,敲低组细胞增殖能力显著下降(P<0.001);细胞划痕实验显示,相较于NC组,敲低组细胞迁移能力同样下降(P<0.05);Western Blot显示,相对于NC组,敲低组细胞的E-cadherin表达水平回升,N-cadherin、Vimentin表达水平下降(P<0.05)。结论:LINC00543在胃癌组织和细胞中高表达,高表达的LINC00543促进胃癌细胞的增殖和迁移,并可能通过EMT途径调控胃癌细胞的迁移能力。 展开更多
关键词 胃癌 LINC00543 EMT 增殖 迁移
暂未订购
尿外泌体非编码RNA在特发性膜性肾病中的研究进展
18
作者 高枫 宫佩琪 +2 位作者 尹敏 李娜 刘锋 《中国实验诊断学》 2025年第4期471-476,共6页
特发性膜性肾病(IMN)是肾病综合征最常见的病理类型,其特征为肾小球系膜广泛增厚和电子致密物沉积。现有诊断方法具有创伤性,迫切需要开发新型无创生物标志物。本综述系统探讨了尿外泌体非编码RNA在特发性膜性肾病发病机制和诊断中的研... 特发性膜性肾病(IMN)是肾病综合征最常见的病理类型,其特征为肾小球系膜广泛增厚和电子致密物沉积。现有诊断方法具有创伤性,迫切需要开发新型无创生物标志物。本综述系统探讨了尿外泌体非编码RNA在特发性膜性肾病发病机制和诊断中的研究进展。综述重点分析了微小RNA(miRNA)、长非编码RNA(lncRNA)和环状RNA(circRNA)三类非编码RNA的分子机制。研究发现,这些尿外泌体非编码RNA在揭示IMN复杂的免疫学过程,包括免疫复合物沉积、肾小球损伤和足细胞损伤等方面具有重要意义。研究结果表明,这些非编码RNA作为潜在的诊断生物标志物,为IMN的分子机制研究和精准诊疗提供了新思路。 展开更多
关键词 特发性膜性肾病 外泌体 非编码RNA 生物标志物
暂未订购
Effect of electroacupuncture on inflammatory signal expression in local tissues of rats with chronic pelvic pain syndrome based on purinergic 2X7 receptor/NOD-like receptor pyrin domaincontaining 3 signal pathway
19
作者 XU Chang li na +7 位作者 WU Xiaoling DAI Xingye YANG Zhiwen SUN Qianhui SHI Tianyu CHAI Yemao PANG Dandan CHENG Kai 《Journal of Traditional Chinese Medicine》 SCIE CSCD 2022年第6期965-971,共7页
OBJECTIVES: To study the expression of inflammatory signal in local prostate tissue of chronic pelvic pain syndrome(CPPS) rats by electroacupuncture(EA) of Guanyuan(CV4), Zhongji(CV3), Huiyang(BL35) and Sanyinjiao(SP6... OBJECTIVES: To study the expression of inflammatory signal in local prostate tissue of chronic pelvic pain syndrome(CPPS) rats by electroacupuncture(EA) of Guanyuan(CV4), Zhongji(CV3), Huiyang(BL35) and Sanyinjiao(SP6), and to explore the possible mechanism of anti-inflammatory and analgesic effects of EA. METHODS : A total of 36 Sprague-Dawley male rats were randomly divided into three groups: control, model and EA(n=12 rats/group). The CPPS model was made by injection of CFA into ventral lobes of the prostate(0.1 m L). Electric acupuncture apparatus was applied to stimulate Guanyuan(CV4), Zhongji(CV3), bilateral Huiyang(BL35) and Sanyinjiao(SP6) acupoints in EA group. The general condition of rats was observed and the prostate index(PI) was calculated. The thermal pain threshold was collected after each therapeutic course. Histopathological changes of the prostate tissue were examined by hematoxylin-eosin staining method. The expression levels of tumor necrosis factor α(TNF-α), interleukin-1β(IL-1β) and prostaglandin E2(PGE2) in prostatic homogenates were measured by enzyme linked immunosorbent assay(ELISA). Moreover, the expression levels of purinergic 2X7 receptor(P2X7R), NOD-like receptor pyrin domain-containing 3(NLRP3), caspase-1 and interleukin-18(IL-18) m RNA were quantified by quantitative real-time polymerase chain reaction. RESULTS: Compared with control group, the PI of rats increased, and the thermal pain threshold decreased significantly in model group. The morphological structure of prostate tissues of rats in model group was severely damaged with a large number of inflammatory cells infiltration. Additionally, the levels of TNF-α, IL-1β and PGE2 were higher, and the expressions of P2X7R, NLRP3, caspase-1 and IL-18 m RNA were higher than those in control group. After EA treatment, the PI was significantly decreased, the thermal pain threshold was significantly increased, and the tissue damage was significantly improved. The expressions of inflammatory cytokines were lower in EA group, and expression of P2X7R/NLRP3 pathway was down-regulated. CONCLUSION: The effect of EA at Guanyuan(CV4), Zhongji(CV3), Huiyang(BL35) and Sanyinjiao(SP6) can improve inflammation and pain symptoms of CPPS rats induced by Complete Freund’s adjuvant(CFA). This suggests that EA at Guanyuan(CV4), Zhongji(CV3), Huiyang(BL35) and Sanyinjiao(SP6) can produce antiinflammatory analgesia effect by preventing the activation of P2X7R/NLRP3 signal pathway, inhibit the release of inflammatory cytokines in CPPS rats, which may provide a putative novel target for the treatment of CPPS. 展开更多
关键词 ELECTROACUPUNCTURE INFLAMMATORY cytokines receptors purinergic P2X7 NLR family pyrin domain-containing 3 protein signal transduction chronic pelvic pain syndrome
原文传递
Mobility and equilibrium stability analysis of pin-jointed mechanisms with equilibrium matrix SVD
20
作者 LU Jin-yu LUO Yao-zhi li na 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第7期1091-1100,共10页
Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equil... Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equilibrium stability of mechanisms according to the effects of the external loads. The first and second variations of the potential energy function of mechanisms under conservative force field are analyzed. Based on the singular value decomposition (SVD) method, a new crite- rion for the mobility and equilibrium stability of mechanisms can be concluded by analyzing the equilibrium matrix. The mobility and stability of mechanisms can be classified by unified matrix formulae. A number of examples are given to demonstrate the proposed criterion. In the end, criteria are summarized in a table. 展开更多
关键词 Pin-jointed mechanisms Criteria for stability of equilibrium Criteria for mobility Potential energy function Equilibrium matrix. Singular value decomposition (SVD) method
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部