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   559652篇
  免费   48076篇
  国内免费   1014篇
  2018年   15663篇
  2017年   14317篇
  2016年   12646篇
  2015年   7567篇
  2014年   8590篇
  2013年   13168篇
  2012年   19097篇
  2011年   27906篇
  2010年   21289篇
  2009年   16421篇
  2008年   23093篇
  2007年   25211篇
  2006年   14216篇
  2005年   13535篇
  2004年   13970篇
  2003年   13613篇
  2002年   13029篇
  2001年   18961篇
  2000年   19100篇
  1999年   14962篇
  1998年   5486篇
  1997年   5693篇
  1996年   5461篇
  1995年   5147篇
  1994年   5052篇
  1993年   5020篇
  1992年   12731篇
  1991年   12494篇
  1990年   12456篇
  1989年   12161篇
  1988年   11496篇
  1987年   10825篇
  1986年   10092篇
  1985年   10577篇
  1984年   8880篇
  1983年   7650篇
  1982年   5997篇
  1981年   5394篇
  1980年   5011篇
  1979年   8415篇
  1978年   6611篇
  1977年   6258篇
  1976年   5963篇
  1975年   6488篇
  1974年   6976篇
  1973年   6847篇
  1972年   6551篇
  1971年   5989篇
  1970年   4959篇
  1969年   4982篇
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
61.
Experiments were made on rabbit fed an atherogenic diet (0.5 g/kg cholesterol) singly for 15 and 24 h and repeatedly for 3, 9 and 30 days. At early stages of lipid metabolism distress the interrelationship was established between blood rheological disorders and microcirculatory abnormalities. The dependence of the initial reaction of some rheological characteristics on their initial level was marked.  相似文献   
62.
63.
Electron microscopy of the adrenal medulla and cortex during the intermediate period of endotoxin shock has revealed severe destructive changes in parenchymal cells. These changes are the reason for synthetic, secretory and trophic disturbances of glandular functions. Ultrastructural lesions indicate that stress exposure exceeds the adaptive capacity of cells, the majority of which are exhausted and killed.  相似文献   
64.
With DNA sequencing now getting cheaper more quickly than data storage or computation, the time may have come for genome informatics to migrate to the cloud.  相似文献   
65.
66.
Synthesis of prenylquinones in chloroplasts   总被引:3,自引:0,他引:3  
  相似文献   
67.
Growth of fathead minnow yolk sac larvae was characterized from changes in dry weight and total content and concentrations of RNA, DNA and protein in fish exposed to a sublethal level of HCN (58 micrograms/l) and in age matched controls. Cyanide toxicosis occurred within 24 hr of exposure as evidenced by significant reductions in protein and RNA content and RNA/DNA ratio of larvae. After 96 hr exposure to HCN, larvae exhibited the same growth rate and protein synthetic rate (RNA/DNA) as control fish. HCN toxicosis and recovery is rapid and at least partial tolerance to HCN develops within 96 hr of exposure in larval fathead minnows.  相似文献   
68.
69.
G R Otten  M R Loken 《Cytometry》1982,3(3):182-187
Forward angle light scattering of two different wavelengths by cells in a flow cytometer was used to investigate physical differences between lymphocytes of different lineage, functional subclass and developmental stage. Correlation of the ultraviolet (UV: 351 nm and 364 nm) and 488 nm light scattering signals produced by lymphoid cells demonstrated that the two signals were not equivalent and that they placed different emphasis on the physical parameters characterizing lymphocytes. Both small T and B lymphocytes from peripheral lymphoid tissues and mitogenically activated large T and B lymphocyte blasts were discriminated by both wavelengths. Differences between the Lyt-2 negative and Lyt-2 positive T lymphocyte subsets were also apparent. Two color light scattering could also discriminate between immature thymocytes and mature peripheral T cells and between small bone marrow cells and mature peripheral B cells. In bone marrow an increase in UV light scattering coincided with the appearance of cell surface immunoglobulin on small cells. These data establish that two color light scattering is a sensitive probe for distinguishing cells of apparently similar morphology and that it can be used to study the physical changes that occur during lymphoid cell differentiation.  相似文献   
70.
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