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   11535篇
  免费   468篇
  国内免费   68篇
耳鼻咽喉   117篇
儿科学   210篇
妇产科学   129篇
基础医学   1486篇
口腔科学   471篇
临床医学   662篇
内科学   2834篇
皮肤病学   202篇
神经病学   796篇
特种医学   524篇
外科学   2038篇
综合类   34篇
一般理论   1篇
预防医学   367篇
眼科学   107篇
药学   823篇
中国医学   42篇
肿瘤学   1228篇
  2022年   60篇
  2021年   164篇
  2020年   72篇
  2019年   108篇
  2018年   144篇
  2017年   118篇
  2016年   163篇
  2015年   172篇
  2014年   233篇
  2013年   294篇
  2012年   478篇
  2011年   542篇
  2010年   305篇
  2009年   279篇
  2008年   542篇
  2007年   607篇
  2006年   597篇
  2005年   720篇
  2004年   693篇
  2003年   703篇
  2002年   695篇
  2001年   254篇
  2000年   228篇
  1999年   263篇
  1998年   197篇
  1997年   196篇
  1996年   145篇
  1995年   145篇
  1994年   163篇
  1993年   132篇
  1992年   205篇
  1991年   193篇
  1990年   186篇
  1989年   173篇
  1988年   204篇
  1987年   199篇
  1986年   171篇
  1985年   162篇
  1984年   127篇
  1983年   82篇
  1982年   62篇
  1981年   76篇
  1980年   64篇
  1979年   69篇
  1978年   60篇
  1977年   60篇
  1976年   49篇
  1975年   50篇
  1971年   58篇
  1969年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
PURPOSE: To clarify the appropriate concentration and dose of hypertonic saline solution (HSS) for preventing delayed neuronal death in the hippocampal CA1 subfield after transient forebrain ischemia in gerbils. METHODS: Thirty gerbils were randomly assigned to five groups: physiological saline solution (PSS) group, ischemia/reperfusion treated with PSS 2 mL x kg(-1); 5% HSS group, treated with 5% HSS 2 mL x kg(-1); 7.5% HSS group, treated with 7.5% HSS 2 mL x kg(-1); 10% HSS group, treated with 10% HSS 2 mL x kg(-1); 20% HSS group, treated with 20% HSS 2 mL x kg(-1). Transient forebrain ischemia was induced by occluding the bilateral common carotid arteries for four minutes. Five days later, histopathological changes in the hippocampal area were examined, and the degenerative ratio of the pyramidal cells were measured according to the following formula: (number of degenerative pyramidal cells/total number of pyramidal cells per 1 mm of hippocampal CA1 subfield) x 100. RESULTS: In PSS and 20% groups, neuronal cell damage was observed five days after ischemia. In the other three groups, these changes were not observed. The degenerative ratios of pyramidal cells were as follows; PSS group: 91.6 +/- 5.6%, 5% HSS group: 7.2 +/- 1.6%, 7.5% group: 8.3 +/- 1.4%, 10% HSS group: 6.2 +/- 1.1%, 20% HSS group: 85.8 +/- 8.7% (P < 0.05; PSS and 20% HSS vs three other groups). CONCLUSION: This study demonstrates that 5, 7.5 or 10% HSS 2 mL x kg(-1) may prevent delayed neuronal death in the hippocampal CA1 subfield after cerebral ischemia/reperfusion in gerbils.  相似文献   
5.
6.
Kindling of the visual cortex in cats: comparison with amygdaloid kindling   总被引:3,自引:0,他引:3  
Kindling of the primary visual cortex (VC) was compared with that of the amygdala in cats. VC kindling was basically similar to kindling of the amygdala in that daily electrical stimulation can lead to the development of a generalized convulsion in most subjects, a growth of afterdischarges in their configuration and duration, and a reduction of the afterdischarge threshold. The kindling response of the VC differed from that of the amygdala in a number of respects, i.e., a high afterdischarge threshold, a different pattern of behavioral seizure development, an abrupt growth of electroclinical seizures coincident with the onset of a generalized convulsion, an intersubject variability in seizure susceptibility, and a marked seizure instability. In VC kindling the afterdischarge propagation into the amygdala was not observed until the generalized convulsion developed, and the early involvement of afterdischarge was seen in the pulvinar, lateral geniculate body, and superior colliculus. These data suggest that a neural mechanism different from amygdaloid kindling may participate in VC kindling, and that the subcortical structures of the visual system are involved in the preferential pathway for a seizure generalization from the VC.  相似文献   
7.
The effect of electric charge on the hepatic disposition of macromolecules was studied in the rat. Charged derivatives of dextran (T-70) and bovine serum albumin (BSA), mitomycin C–dextran conjugates (MMC-D), and lactosaminated BSA (Lac-BSA) were employed as model macromolecules. After intravenous injection, cationic macromolecules were rapidly eliminated from plasma because of their extensive hepatic uptake, while anionic and neutral macromolecules were slowly eliminated. Cationic macromolecules were recovered from parenchymal and nonparenchymal hepatic cells at a cellular uptake (per unit cell number) ratio of 1.4–3.2, while that of Lac-BSA was 14. During liver perfusion using a single-pass constant infusion mode, cationic macromolecules were continuously extracted by the liver, with extraction ratios at steady-state (E ss) ranging between 0.03 and 0.54, whereas anionic and neutral macromolecules were almost completely recovered in the outflow at steady state. The E ss for cationized BSA (Cat-BSA) and cationic MMC-Dcat were concentration dependent and decreased at low temperatures and in the presence of colchicine and cytochalasin B. The possible participation of the internalization process in the uptake of cationic macromolecules by hepatocytes was suggested.  相似文献   
8.
9.
10.
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