城市POI的分布情况客观反映了一个城市各行各业的发展情况,传统获取POI的测绘手段成本高、更新周期长、时效性差,而基于位置的社交网络(Location-Based Social Network,LBSN)平台的发展为实现城市POI的感知提供了一种新思路。本文提出...城市POI的分布情况客观反映了一个城市各行各业的发展情况,传统获取POI的测绘手段成本高、更新周期长、时效性差,而基于位置的社交网络(Location-Based Social Network,LBSN)平台的发展为实现城市POI的感知提供了一种新思路。本文提出一种基于LBSN数据聚类分析的城市POI感知方法,首先,对LBSN数据进行预处理,包括清洗重复数据、删除无效数据、数据预分类等,以提高数据的有效性;其次,提出一种改进的DBSCAN算法,对处理后的数据进行聚类分析,从而得到准确度较高的城市各类POI分布情况。实验结果表明,与传统的DBSCAN算法以及K-means算法相比,本文提出的算法有更好的聚类效果,且在聚类指标上有更大的CH指数值和更小的DBI指数值。展开更多
Epidermal growth factor (EGF) is produced primarily by Leydig cells of human testis. Expression of the EGF gene was assessed in mouse testis during the course of sexual maturation by the application of the RT-PCR meth...Epidermal growth factor (EGF) is produced primarily by Leydig cells of human testis. Expression of the EGF gene was assessed in mouse testis during the course of sexual maturation by the application of the RT-PCR method and the use of specific oligonucleotide primers. Testis EGF mRNA content increased with the developmental age of the mice, i.e., day 15 < day 30 < day 45 postnatal. The expression of the EGF gene appears to correlate with maturation of the testis and proliferation of Leydig cells.展开更多
The effects of antisense oligonucleotide to insulin-like growth factor 11 (IGFII) to induce apoptosis in human ovarian cancer cells were evaluated. Antiproliferation effects of antisense to IGFII in ovarian cancer AO ...The effects of antisense oligonucleotide to insulin-like growth factor 11 (IGFII) to induce apoptosis in human ovarian cancer cells were evaluated. Antiproliferation effects of antisense to IGFII in ovarian cancer AO cells were determined by 3H-thymidine incorporation. Apoptosis of the IGFll antisense-treated cells was quantitated by both nuclear condensation and flow cytometry after cells were stained with propidium iodide. IGFII antisense (4.5μM)treatment of 48 h maximally inhibited proliferation of AO cells. More than 25% of IGFII antisense-treated cells (4.5PM for 24 h) had undergone apoptosis, whereas less than 3% of the cells were apoptotic in either IGFII sense-treatedcells or untreated cells. Antisense oligonucleotide to IGFII significantly inhibited cell proliferation and induced apoptosis in human ovarian cancer AO cell. These data suggest that IGFII may be a potential target in treatment of ovarian cancer and antisense oligonucleotide to IGFⅡmay serve as a therapeutic approach.展开更多
The erythroid- and developmental stage-specific expression of the human ε-globin gene is controlled, in part,by the 5’-flanking DNA sequence of this gene. In the present study, we have used DNA-protein binding assay...The erythroid- and developmental stage-specific expression of the human ε-globin gene is controlled, in part,by the 5’-flanking DNA sequence of this gene. In the present study, we have used DNA-protein binding assays to identify trans-acting factors which regulate the temporal expression of the human ε-globin gene during development. Using gel mobility shift assays and DNasel footprinting assays, a nuclear protein factor (termed ε-SSF1) in the nuclear extracts from mouse haematopoietic tissues at d 11 and d 13 of gestation was identified. It could specifically bind to the positive control region (between -535 and -453bp) of the human ε-globin gene. We speculated that the E-SSF1 might be an erythroid- and developmental stage-specific activator. In addition, we found another nuclear protein factor (termed ε-R1) in the nuclear extract from mouse fetal liver at d 18 of gestation, which could strongly bind to the silencer region (between -392 and -177bp) of this gene. Therefore, we speculated that the ε-R1 might be an erythroid- and developmental stagespecific repressor. Our data suggest that both ε-SSF1 and ε-R1 might play important roles in developmental regulation of the human ε-globin gene expression during the early embryonic life. On the other hand, we observed that the binding patterns of nuclear proteins from three cell lines (K562, HEL and Raji) to these regulatory regions were partially different. These results suggest that different trans-acting factors in K562, HEL and Raji cells might be responsible for activating or silencing the human ε-globin gene in three different cell lines.展开更多
In order to study the image characteristics of motion artifacts and todetermine the relations of motion artifacts with varied motion types, and the inag-ing timings, frames, distances and directions during SPECT acqui...In order to study the image characteristics of motion artifacts and todetermine the relations of motion artifacts with varied motion types, and the inag-ing timings, frames, distances and directions during SPECT acquisition, a myocardialphantom filled with pertechnetate solution was used to simulate the patient motion.In nonreturning pattern, the simulation motion was timed at the 0°, -45° and -90°positions during the rotation of the detector over a 180° arc from +45° right antcrioroblique to -135° left posterior oblique. Simulation motion was performed by movingthe phantom +5mm, ±-10mm and +20mm along X- (from left to right), Y- (fromhead to caudal) and Z-axis (from back to ventral) respectively. In returning patternthe acquired 30 projections were divided into three equal parts. The simulation motionwas timed at the middle 1-7 projections of each part and performed by moving thephantom +5, ±10, ±15, ±20, ±25, ±30 and ±50 mm along X-, Y- and Z-axis respec-tively. Each image was compared with normal image and assessed by three experiencedobservers without knowledge of the phantom motion. Logistic regression analysis wasused to determine the relationship of motion artifacts with the affecting factors. Nosignificant artifacts can be found when the phantom was moved slightly, no matterwhich motion pattern, direction and timing were taken. The characteristics of motionartifacts showed a radioactive marker dot in inferior wall firstly when the phantomwas moved along X-axis. Septal and lateral wall became "hot" symmetrically whenthe phantom was moved along Y-axis. And nodular hot could be found in anteriorwall when the phantom was moved along Z-axis. At last the "lumpy" and "defect"areas existed alternately and formed a triangle respectively. The presence of motionartifacts was related to motion directions, distance and affected frames, but was in-dependent of motion timing. The characteristics of motion artifacts could be foundwhen the phantom was moved along different axis. Motion distance contributed moreto the appearance of motion artifacts than other related factors, this was especiallyclear when motion was along Y-axis.展开更多
By using c-Ha-ras-1, N-ras Wigler (left sequence) and P52C.(right sequence), c-sis, v-erbB, c-myc and v-fos oncogenes as probes, restriction fragment length polymorphisms (RFLPs) of tumor tissue DNAs of 95 patients wi...By using c-Ha-ras-1, N-ras Wigler (left sequence) and P52C.(right sequence), c-sis, v-erbB, c-myc and v-fos oncogenes as probes, restriction fragment length polymorphisms (RFLPs) of tumor tissue DNAs of 95 patients with gastric carcinoma, primary hepatic carcinoma and brain tumor, and those of 90 normal individuals were studied with the techniques of Southern blot and dot blot. Gene amplification and recombination were also examined in some tumors simultaneously. Some alleles of oncogene are reported in Chinese population for the first time. Moreover, the characteristic frequency of some "rare" alleles and genotypes occurred in some tumor samples is significantly higher than that occured in normal individuals. Pedigree analysis for 2 patients showed that some "rare" alleles are also abandant. Besides, gene amplification and recombination were found in some tumors.展开更多
The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis...The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis,possibly due to the issues of reactivity and selectivity.In the past decade,the intermolecular D–A reaction has been increasingly utilized in the total synthesis of structurally complex natural products.In this article,we present a few examples for the elegant applications of the intermolecular D–A reaction that are inspired by biosynthetic hypotheses of the target natural products.These examples demonstrate that D–A reaction is not only useful for preparing building blocks but also powerful for coupling structurally complicated and sterically demanding segments in a highly chemo-and stereo-controlled fashion,which may inspire further developments of intermolecular D–A reaction from both strategy and methodology perspectives.展开更多
文摘城市POI的分布情况客观反映了一个城市各行各业的发展情况,传统获取POI的测绘手段成本高、更新周期长、时效性差,而基于位置的社交网络(Location-Based Social Network,LBSN)平台的发展为实现城市POI的感知提供了一种新思路。本文提出一种基于LBSN数据聚类分析的城市POI感知方法,首先,对LBSN数据进行预处理,包括清洗重复数据、删除无效数据、数据预分类等,以提高数据的有效性;其次,提出一种改进的DBSCAN算法,对处理后的数据进行聚类分析,从而得到准确度较高的城市各类POI分布情况。实验结果表明,与传统的DBSCAN算法以及K-means算法相比,本文提出的算法有更好的聚类效果,且在聚类指标上有更大的CH指数值和更小的DBI指数值。
文摘Epidermal growth factor (EGF) is produced primarily by Leydig cells of human testis. Expression of the EGF gene was assessed in mouse testis during the course of sexual maturation by the application of the RT-PCR method and the use of specific oligonucleotide primers. Testis EGF mRNA content increased with the developmental age of the mice, i.e., day 15 < day 30 < day 45 postnatal. The expression of the EGF gene appears to correlate with maturation of the testis and proliferation of Leydig cells.
文摘The effects of antisense oligonucleotide to insulin-like growth factor 11 (IGFII) to induce apoptosis in human ovarian cancer cells were evaluated. Antiproliferation effects of antisense to IGFII in ovarian cancer AO cells were determined by 3H-thymidine incorporation. Apoptosis of the IGFll antisense-treated cells was quantitated by both nuclear condensation and flow cytometry after cells were stained with propidium iodide. IGFII antisense (4.5μM)treatment of 48 h maximally inhibited proliferation of AO cells. More than 25% of IGFII antisense-treated cells (4.5PM for 24 h) had undergone apoptosis, whereas less than 3% of the cells were apoptotic in either IGFII sense-treatedcells or untreated cells. Antisense oligonucleotide to IGFII significantly inhibited cell proliferation and induced apoptosis in human ovarian cancer AO cell. These data suggest that IGFII may be a potential target in treatment of ovarian cancer and antisense oligonucleotide to IGFⅡmay serve as a therapeutic approach.
文摘The erythroid- and developmental stage-specific expression of the human ε-globin gene is controlled, in part,by the 5’-flanking DNA sequence of this gene. In the present study, we have used DNA-protein binding assays to identify trans-acting factors which regulate the temporal expression of the human ε-globin gene during development. Using gel mobility shift assays and DNasel footprinting assays, a nuclear protein factor (termed ε-SSF1) in the nuclear extracts from mouse haematopoietic tissues at d 11 and d 13 of gestation was identified. It could specifically bind to the positive control region (between -535 and -453bp) of the human ε-globin gene. We speculated that the E-SSF1 might be an erythroid- and developmental stage-specific activator. In addition, we found another nuclear protein factor (termed ε-R1) in the nuclear extract from mouse fetal liver at d 18 of gestation, which could strongly bind to the silencer region (between -392 and -177bp) of this gene. Therefore, we speculated that the ε-R1 might be an erythroid- and developmental stagespecific repressor. Our data suggest that both ε-SSF1 and ε-R1 might play important roles in developmental regulation of the human ε-globin gene expression during the early embryonic life. On the other hand, we observed that the binding patterns of nuclear proteins from three cell lines (K562, HEL and Raji) to these regulatory regions were partially different. These results suggest that different trans-acting factors in K562, HEL and Raji cells might be responsible for activating or silencing the human ε-globin gene in three different cell lines.
文摘In order to study the image characteristics of motion artifacts and todetermine the relations of motion artifacts with varied motion types, and the inag-ing timings, frames, distances and directions during SPECT acquisition, a myocardialphantom filled with pertechnetate solution was used to simulate the patient motion.In nonreturning pattern, the simulation motion was timed at the 0°, -45° and -90°positions during the rotation of the detector over a 180° arc from +45° right antcrioroblique to -135° left posterior oblique. Simulation motion was performed by movingthe phantom +5mm, ±-10mm and +20mm along X- (from left to right), Y- (fromhead to caudal) and Z-axis (from back to ventral) respectively. In returning patternthe acquired 30 projections were divided into three equal parts. The simulation motionwas timed at the middle 1-7 projections of each part and performed by moving thephantom +5, ±10, ±15, ±20, ±25, ±30 and ±50 mm along X-, Y- and Z-axis respec-tively. Each image was compared with normal image and assessed by three experiencedobservers without knowledge of the phantom motion. Logistic regression analysis wasused to determine the relationship of motion artifacts with the affecting factors. Nosignificant artifacts can be found when the phantom was moved slightly, no matterwhich motion pattern, direction and timing were taken. The characteristics of motionartifacts showed a radioactive marker dot in inferior wall firstly when the phantomwas moved along X-axis. Septal and lateral wall became "hot" symmetrically whenthe phantom was moved along Y-axis. And nodular hot could be found in anteriorwall when the phantom was moved along Z-axis. At last the "lumpy" and "defect"areas existed alternately and formed a triangle respectively. The presence of motionartifacts was related to motion directions, distance and affected frames, but was in-dependent of motion timing. The characteristics of motion artifacts could be foundwhen the phantom was moved along different axis. Motion distance contributed moreto the appearance of motion artifacts than other related factors, this was especiallyclear when motion was along Y-axis.
文摘By using c-Ha-ras-1, N-ras Wigler (left sequence) and P52C.(right sequence), c-sis, v-erbB, c-myc and v-fos oncogenes as probes, restriction fragment length polymorphisms (RFLPs) of tumor tissue DNAs of 95 patients with gastric carcinoma, primary hepatic carcinoma and brain tumor, and those of 90 normal individuals were studied with the techniques of Southern blot and dot blot. Gene amplification and recombination were also examined in some tumors simultaneously. Some alleles of oncogene are reported in Chinese population for the first time. Moreover, the characteristic frequency of some "rare" alleles and genotypes occurred in some tumor samples is significantly higher than that occured in normal individuals. Pedigree analysis for 2 patients showed that some "rare" alleles are also abandant. Besides, gene amplification and recombination were found in some tumors.
基金financially supported by the Ministry of Science&Technology(2013CB836900)the National Natural Science Foundation of China(21290180,21172235,and 21222202)the Chinese Academy of Sciences
文摘The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis,possibly due to the issues of reactivity and selectivity.In the past decade,the intermolecular D–A reaction has been increasingly utilized in the total synthesis of structurally complex natural products.In this article,we present a few examples for the elegant applications of the intermolecular D–A reaction that are inspired by biosynthetic hypotheses of the target natural products.These examples demonstrate that D–A reaction is not only useful for preparing building blocks but also powerful for coupling structurally complicated and sterically demanding segments in a highly chemo-and stereo-controlled fashion,which may inspire further developments of intermolecular D–A reaction from both strategy and methodology perspectives.
