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   69401篇
  免费   2521篇
  国内免费   1834篇
  2023年   631篇
  2022年   817篇
  2021年   2048篇
  2020年   1223篇
  2019年   1671篇
  2018年   1356篇
  2017年   1008篇
  2016年   1577篇
  2015年   3395篇
  2014年   6834篇
  2013年   6285篇
  2012年   4836篇
  2011年   5628篇
  2010年   3918篇
  2009年   3384篇
  2008年   3486篇
  2007年   3790篇
  2006年   2399篇
  2005年   2069篇
  2004年   1264篇
  2003年   1005篇
  2002年   907篇
  2001年   628篇
  2000年   542篇
  1999年   566篇
  1998年   507篇
  1997年   395篇
  1996年   441篇
  1995年   601篇
  1994年   499篇
  1993年   549篇
  1992年   491篇
  1991年   503篇
  1990年   431篇
  1989年   443篇
  1988年   432篇
  1987年   363篇
  1986年   330篇
  1985年   549篇
  1984年   870篇
  1983年   549篇
  1982年   724篇
  1981年   723篇
  1980年   543篇
  1979年   523篇
  1978年   323篇
  1977年   343篇
  1976年   307篇
  1974年   226篇
  1973年   240篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Degeneration of mesencephalic dopaminergic (mesDA) neurons is the pathological hallmark of Parkinson’s diseae. Study of the biological processes involved in physiological functions and vulnerability and death of these neurons is imparative to understanding the underlying causes and unraveling the cure for this common neurodegenerative disorder. Primary cultures of mesDA neurons provide a tool for investigation of the molecular, biochemical and electrophysiological properties, in order to understand the development, long-term survival and degeneration of these neurons during the course of disease. Here we present a detailed method for the isolation, culturing and maintenance of midbrain dopaminergic neurons from E12.5 mouse (or E14.5 rat) embryos. Optimized cell culture conditions in this protocol result in presence of axonal and dendritic projections, synaptic connections and other neuronal morphological properties, which make the cultures suitable for study of the physiological, cell biological and molecular characteristics of this neuronal population.  相似文献   
7.
Mycobacterium tuberculosis complex (MTBC) is notorious for causing diseases, such as tuberculosis. Tuberculosis caused by M. tuberculosis remains a global public health concern. Two prophages, phiRv1 and phiRv2, can be found among most MTBC genomes. However, no precise functions have been assigned for the two prophages. In this paper, to find out the function of these two prophages, the distribution and function of phiRv1 and phiRv2 in MTBC genomes were analyzed from multiple omics data. We found that complex insertion, deletion, and reorganization appeared on the locus of two prophages in MTBC genomes; some genes of the two prophages can be translated and are functional from proteomic data; the expression of other prophage genes, such as Rv1577c, Rv2650c, Rv2652c, Rv2659c, and Rv2658c, can vary with environmental stresses and might enhance the fitness of MTBC. These data will facilitate our in-depth understanding of their function.  相似文献   
8.
In an effort to identify a potential back-up to apixaban (Eliquis®), we explored a series of diversified P4 moieties. Several analogs with substituted gem-dimethyl moieties replacing the terminal lactam of apixaban were identified which demonstrated potent FXa binding affinity (FXa Ki), good human plasma anticoagulant activity (PT EC2x), cell permeability, and oral bioavailability.  相似文献   
9.
10.
Abstract. Anopheles stephensi mosquitoes which had fed upon mice infected with Plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. Fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. Egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of P.y. nigeriensis in the blood affected this relationship. Reduced fecundity was associated with a significant reduction of bloodmeal size (measured by haematin excretion) in mosquitoes which ingested gametocytaemic blood. The bloodmeal size in mosquitoes fed on parasitaemic blood without gametocytes was not significantly reduced. The use of haematin assays for determination of bloodmeal size in mosquitoes is discussed.  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