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   758160篇
  免费   81541篇
  国内免费   1421篇
  2016年   7846篇
  2015年   10955篇
  2014年   12904篇
  2013年   18823篇
  2012年   20539篇
  2011年   21051篇
  2010年   14167篇
  2009年   13103篇
  2008年   18639篇
  2007年   19589篇
  2006年   18489篇
  2005年   17803篇
  2004年   17757篇
  2003年   17175篇
  2002年   16966篇
  2001年   32209篇
  2000年   32686篇
  1999年   26281篇
  1998年   9096篇
  1997年   9584篇
  1996年   9020篇
  1995年   8542篇
  1994年   8393篇
  1993年   8390篇
  1992年   22062篇
  1991年   21578篇
  1990年   21366篇
  1989年   20852篇
  1988年   19664篇
  1987年   18567篇
  1986年   17567篇
  1985年   17963篇
  1984年   14933篇
  1983年   12863篇
  1982年   10057篇
  1981年   9183篇
  1980年   8478篇
  1979年   14409篇
  1978年   11477篇
  1977年   10653篇
  1976年   10128篇
  1975年   11180篇
  1974年   12280篇
  1973年   12081篇
  1972年   11190篇
  1971年   10163篇
  1970年   8807篇
  1969年   8811篇
  1968年   8105篇
  1967年   6934篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
91.
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   
92.
93.
94.
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   
95.
96.
Synthesis of prenylquinones in chloroplasts   总被引:3,自引:0,他引:3  
  相似文献   
97.
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   
98.
99.
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   
100.
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