首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   131篇
  免费   6篇
  国内免费   57篇
  2024年   1篇
  2023年   5篇
  2022年   6篇
  2021年   7篇
  2020年   8篇
  2019年   6篇
  2018年   4篇
  2017年   4篇
  2016年   5篇
  2015年   3篇
  2014年   12篇
  2013年   13篇
  2012年   13篇
  2011年   8篇
  2010年   8篇
  2009年   13篇
  2008年   14篇
  2007年   7篇
  2006年   7篇
  2005年   6篇
  2004年   5篇
  2003年   3篇
  2002年   5篇
  2001年   1篇
  2000年   11篇
  1999年   7篇
  1998年   1篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1988年   1篇
  1987年   1篇
  1985年   3篇
  1984年   1篇
排序方式: 共有194条查询结果,搜索用时 15 毫秒
31.

Background  

Mulberry dwarf (MD), which is caused by phytoplasma, is one of the most serious infectious diseases of mulberry. Phytoplasmas have been associated with diseases in several hundred plant species. The inability to culture phytoplasmas in vitro has hindered their characterization at the molecular level. Though the complete genomes of two phytoplasmas have been published, little information has been obtained about the proteome of phytoplasma. Therefore, the proteomic information of phytoplasmas would be useful to elucidate the functional mechanisms of phytoplasma in many biological processes.  相似文献   
32.
3H11Ag, a tumor-associated antigen defined by the monoclonal antibody 3H11 that specifically recognizes cancer cells in various tumor tissues, was successfully cloned recently, but its function is unknown. To explore the potential roles it plays in tumors, we analyzed its subcellular localization in the present study. By expressing 3H11Ag fused with fluorescent protein in COS-7 cells, we found that 3H11Ag localizes to both cytoplasm and nucleus, which was confirmed by subcellular fractionation. And sequentially extracting the nuclei of COS-7 cells transfected with 3H11Ag showed that it is a DNA- and nuclear matrix-associated protein. Moreover, by expressing a series of red fluorescent protein-tagged truncated forms of 3H11Ag, it was demonstrated that the 150 amino acid residues at its C-terminal are fully responsible for the subcellular localization. In addition, the results of the computational analysis of 3H11Ag were in accordance with those of the experimental analysis. All these data would be helpful to elucidate the functions of 3H11Ag.  相似文献   
33.
测定处于不同纬度的浙江杭州和福建宁德的蓝尾石龙子(Eumeceselegans)种群的个体大小和繁殖特征。宁德种群的产卵时间为5月27日—6月22日,早于高纬度杭州种群(6月4日—7月12日)。宁德种群最小繁殖雌体及性成熟个体大小均显著小于杭州种群。宁德和杭州两种群的相对窝卵重无显著差异;当统计去除母体体长的影响之后,两地种群的窝卵数和窝卵重也无显著差异,但杭州种群的卵重量显著大于宁德种群。蓝尾石龙子窝卵数和卵重量呈负相关,窝卵数和卵大小的权衡存在种群间差异。特定窝卵数条件下,杭州种群的卵重量显著大于宁德种群。由此可见,蓝尾石龙子种群间的繁殖生活史特征存在显著差异,而且与母体大小的差异密切相关。推测不同纬度地区的蓝尾石龙子种群的繁殖策略存在差异。  相似文献   
34.
35.
中国外来入侵植物研究现状及存在的问题   总被引:5,自引:0,他引:5  
生物入侵是当今各国发展的一大挑战,特别是像中国这样的发展中国家。然而,我们对外来入侵种的本底资料还很不清楚,更缺乏相关的深入调查;对生物入侵所造成的生态和经济影响还没有引起足够的重视,同时也忽视了盲目引种可能带来的各种危害。本文在文献调研的基础上,从外来植物的入侵历史和文化、中国外来入侵植物的调查现状、外来植物入侵对生态安全及经济的影响等方面进行了全面系统的总结,并提出了中国外来入侵植物研究领域存在的问题及应对措施。  相似文献   
36.
Adherence to TB treatment is the most important requirement for efficient TB control. Migrant TB patients’ “migratory” nature affects the adherence negatively, which presents an important barrier for National TB Control Program in China. Therefore, TB control among migrants is of high importance.The aim of this study is to describe adherence to TB treatment among migrant TB patients and to identify factors associated with adherence. A total of 12 counties/districts of Shandong Province, China were selected as study sites. 314 confirmed smear positive TB patients were enrolled between August 2nd 2008 and October 17th 2008, 16% of whom were non-adherent to TB therapy. Risk factors for non-adherence were: the divorced or bereft of spouse, patients not receiving TB-related health education before chemotherapy, weak incentives for treatment adherence, and self supervision on treatment. Based on the risk factors identified, measures are recommended such as implementing health education for all migrant patients before chemotherapy and encouraging primary care workers to supervise patients.  相似文献   
37.

Purpose

This study aims to explore gene expression signatures and serum biomarkers to predict intrinsic chemoresistance in epithelial ovarian cancer (EOC).

Patients and Methods

Gene expression profiling data of 322 high-grade EOC cases between 2009 and 2010 in The Cancer Genome Atlas project (TCGA) were used to develop and validate gene expression signatures that could discriminate different responses to first-line platinum/paclitaxel-based treatments. A gene regulation network was then built to further identify hub genes responsible for differential gene expression between the complete response (CR) group and the progressive disease (PD) group. Further, to find more robust serum biomarkers for clinical application, we integrated our gene signatures and gene signatures reported previously to identify secretory protein-encoding genes by searching the DAVID database. In the end, gene-drug interaction network was constructed by searching Comparative Toxicogenomics Database (CTD) and literature.

Results

A 349-gene predictive model and an 18-gene model independent of key clinical features with high accuracy were developed for prediction of chemoresistance in EOC. Among them, ten important hub genes and six critical signaling pathways were identified to have important implications in chemotherapeutic response. Further, ten potential serum biomarkers were identified for predicting chemoresistance in EOC. Finally, we suggested some drugs for individualized treatment.

Conclusion

We have developed the predictive models and serum biomarkers for platinum/paclitaxel response and established the new approach to discover potential serum biomarkers from gene expression profiles. The potential drugs that target hub genes are also suggested.  相似文献   
38.
高等植物性别分化研究进展   总被引:5,自引:0,他引:5  
寿森炎  汪俏梅 《植物学报》2000,17(6):528-535
高等植物性别分化研究主要包括三个方面:性别分化特异大分子标记物的鉴定(分化程序);诱导信号(如植物激素)的分析和性决定基因的分离与分析。近年来,植物性别分化研究取得了较大进展,本文主要介绍这一研究在分化程序、诱导信号和性决定基因等方面的研究进展。  相似文献   
39.
用富集文库克隆人胰岛素基因组基因   总被引:1,自引:0,他引:1  
通过构建可富集人胰岛素基因的λ噬菌体文库,克隆了人胰岛素基因组基因.首先从中国人血液白细胞中提取到人基因组DNA,用EcoRⅠ和BglⅡ对基因组DNA进行全酶切,经0.4%琼脂糖凝胶电泳,特异回收9.5kb左右的DNA片段.将该片段与λEMBL3/BamHⅠ臂连接,构建成一个特殊的人基因组λ噬菌体文库(富集文库),效价为2×104.同时采用PCR方法及用引物Ⅰ:5′GGACAGGCTACATCAGGAAGAGG3′,引物Ⅱ:5′CTGCGTCTAATTGCAGTAGTTC3′,从人基因组DNA中扩增出一段含胰岛素基因的1.36kbDNA片段,做为放射性标记探针,对文库进行了噬菌斑原位杂交筛选,从1×104个噬菌斑中筛选到一个含人胰岛素基因组基因的阳性克隆,并进一步完成了亚克隆和该基因1732bpDNA序列的测定.结果该基因的1732bpDNA序列包括部分5′端和3′端与国外发表的人胰岛素α型等位基因的序列相同  相似文献   
40.
The climatic oscillations of the last glacial period have had profound influences on the demography and levels of genetic diversity of extant species. Molecular evidence of glacial effects on temperate species has been well documented, whereas little is known regarding that on subtropical species. Here we present analyses based on partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene (1052 bp) and genotypes at 15 microsatellite loci to investigate the historical demography, population structure and ongoing gene flow of an undescribed fig‐pollinating wasp (Ceratosolen sp. 1) of Ficus septica in subtropical Taiwan. Reconstructed historical demography based on the coalescent tree of COI sequences suggests that C. sp. 1 has undergone a drastic population expansion which was tightly coupled with climatic changes since the last glacial maximum (LGM). The magnitude of the population size change was approximately 500‐fold, indicating that the population of this wasp and its host was likely highly compressed during the last glacial period. The lack of significant population differentiation (FST < 0.02, for all pairwise FST values) may be due to rapid postglacial expansion facilitated by long‐distance dispersal, although a low frequency of first‐generation migrants was detected. Our results clearly demonstrate how recent climatic changes since the LGM and dispersal ability have jointly shaped the genetic composition of a subtropical fig‐pollinating wasp.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号