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   62375篇
  免费   4937篇
  国内免费   4726篇
  72038篇
  2024年   149篇
  2023年   840篇
  2022年   1950篇
  2021年   3223篇
  2020年   2216篇
  2019年   2676篇
  2018年   2510篇
  2017年   1960篇
  2016年   2772篇
  2015年   3903篇
  2014年   4674篇
  2013年   4777篇
  2012年   5684篇
  2011年   5124篇
  2010年   3109篇
  2009年   2771篇
  2008年   3188篇
  2007年   2834篇
  2006年   2436篇
  2005年   2045篇
  2004年   1677篇
  2003年   1542篇
  2002年   1210篇
  2001年   990篇
  2000年   937篇
  1999年   881篇
  1998年   544篇
  1997年   505篇
  1996年   514篇
  1995年   450篇
  1994年   443篇
  1993年   345篇
  1992年   479篇
  1991年   336篇
  1990年   295篇
  1989年   274篇
  1988年   224篇
  1987年   207篇
  1986年   186篇
  1985年   165篇
  1984年   127篇
  1983年   141篇
  1982年   84篇
  1981年   46篇
  1980年   56篇
  1979年   69篇
  1976年   49篇
  1974年   59篇
  1973年   51篇
  1972年   55篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
F Zhu  XH Ma  C Qin  L Tao  X Liu  Z Shi  CL Zhang  CY Tan  YZ Chen  YY Jiang 《PloS one》2012,7(7):e39782
Due to extensive bioprospecting efforts of the past and technology factors, there have been questions about drug discovery prospect from untapped species. We analyzed recent trends of approved drugs derived from previously untapped species, which show no sign of untapped drug-productive species being near extinction and suggest high probability of deriving new drugs from new species in existing drug-productive species families and clusters. Case histories of recently approved drugs reveal useful strategies for deriving new drugs from the scaffolds and pharmacophores of the natural product leads of these untapped species. New technologies such as cryptic gene-cluster exploration may generate novel natural products with highly anticipated potential impact on drug discovery.  相似文献   
994.
Li S  Zhu J  Fu H  Wan J  Hu Z  Liu S  Li J  Tie Y  Xing R  Zhu J  Sun Z  Zheng X 《Nucleic acids research》2012,40(2):884-891
microRNAs (miRNAs) are a versatile class of non-coding RNAs involved in regulation of various biological processes. miRNA-122 (miR-122) is specifically and abundantly expressed in human liver. In this study, we employed 3'-end biotinylated synthetic miR-122 to identify its targets based on affinity purification. Quantitative RT-PCR analysis of the affinity purified RNAs demonstrated a specific enrichment of several known miR-122 targets such as CAT-1 (also called SLC7A1), ADAM17 and BCL-w. Using microarray analysis of affinity purified RNAs, we also discovered many candidate target genes of miR-122. Among these candidates, we confirmed that protein kinase, interferon-inducible double-stranded RNA-dependent activator (PRKRA), a Dicer-interacting protein, is a direct target gene of miR-122. miRNA quantitative-RT-PCR results indicated that miR-122 and small interfering RNA against PRKRA may facilitate the accumulation of newly synthesized miRNAs but did not detectably affect endogenous miRNAs levels. Our findings will lead to further understanding of multiple functions of this hepato-specific miRNA. We conclude that miR-122 could repress PRKRA expression and facilitate accumulation of newly synthesized miRNAs.  相似文献   
995.
The global insight into the relationships between miRNAs and their regulatory influences remains poorly understood. And most of complex diseases may be attributed to certain local areas of pathway (subpathway) instead of the entire pathway. Here, we reviewed the studies on miRNA regulations to pathways and constructed a bipartite miRNAs and subpathways network for systematic analyzing the miRNA regulatory influences to subpathways. We found that a small fraction of miRNAs were global regulators, environmental information processing pathways were preferentially regulated by miRNAs, and miRNAs had synergistic effect on regulating group of subpathways with similar function. Integrating the disease states of miRNAs, we also found that disease miRNAs regulated more subpathways than nondisease miRNAs, and for all miRNAs, the number of regulated subpathways was not in proportion to the number of the related diseases. Therefore, the study not only provided a global view on the relationships among disease, miRNA and subpathway, but also uncovered the function aspects of miRNA regulations and potential pathogenesis of complex diseases. A web server to query, visualize and download for all the data can be freely accessed at http://bioinfo.hrbmu.edu.cn/miR2Subpath.  相似文献   
996.
Zhong  Zhe  Chen  Weijie  Gao  Huan  Che  Ningning  Xu  Min  Yang  Lanqing  Zhang  Yingfang  Ye  Min 《Neurochemical research》2021,46(11):3050-3058
Neurochemical Research - Gut microbiota is closely related to the Parkinson’s disease (PD) pathogenesis. Additionally, aggregation of α-synuclein (α-syn) is central to PD...  相似文献   
997.
998.
Zhang  M.  Zhang  J.  Jiao  R. T.  Yang  X. E.  Ji  D. W. 《Russian Journal of Plant Physiology》2021,68(6):1115-1124
Russian Journal of Plant Physiology - Hyperaccumulating ecotype (HE) of Sedum alfredii Hance is a Zn/Cd hyperaccumulator, which can accumulate Zn in shoot up to 2% of dry weight, understanding the...  相似文献   
999.
郑雅楠  时勇  李洋  范立淳  王珏  王伟韬 《昆虫学报》2021,64(12):1478-1482
[目的]近年来,松材线虫病扩散到我国的中温带地区,云杉花墨天牛Monochamus saltuarius成为该地区松材线虫的新媒介昆虫.由于中温带地区松材线虫危害松树种类较多,本研究对云杉花墨天牛成虫对4种寄主松树的取食偏好性进行测定,为明确云杉花墨天牛成虫补充营养特性,进而为中温带地区松材线虫病和云杉花墨天牛监测与防...  相似文献   
1000.
用RDA技术寻找肝再生相关基因的初步研究   总被引:2,自引:0,他引:2  
Xu WX  Wang SY  Wei HD  Yang XM 《生理学报》2000,52(4):277-277
利用表达性差异显示分析 (RDA)技术 ,研究大鼠 2 /3肝部分切除后 1h肝组织中基因的选择性表达 ,建立了大鼠 2 /3肝部分切除术后 1h再生肝组织选择性表达基因EST库。该库约含 3× 10 4 个独立克隆 ,其中 95 %以上的克隆含有插入片段 ,长度约 2 0 0~ 70 0bp不等 ,对随机挑出的 5 2个克隆的序列分析表明其中大多数基因与肝再生调控相关 (38/5 2 )。 10株未报道序列经RNA杂交证实 ,其中 6株与肝再生相关。  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