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   1842篇
  免费   133篇
  2022年   16篇
  2021年   43篇
  2020年   21篇
  2019年   31篇
  2018年   42篇
  2017年   39篇
  2016年   50篇
  2015年   64篇
  2014年   68篇
  2013年   98篇
  2012年   159篇
  2011年   134篇
  2010年   97篇
  2009年   83篇
  2008年   109篇
  2007年   119篇
  2006年   91篇
  2005年   105篇
  2004年   105篇
  2003年   77篇
  2002年   78篇
  2001年   29篇
  2000年   16篇
  1999年   17篇
  1998年   17篇
  1997年   15篇
  1996年   11篇
  1995年   14篇
  1994年   8篇
  1993年   9篇
  1992年   12篇
  1991年   15篇
  1990年   10篇
  1989年   9篇
  1988年   17篇
  1987年   10篇
  1986年   11篇
  1985年   5篇
  1984年   10篇
  1983年   6篇
  1982年   11篇
  1981年   7篇
  1980年   10篇
  1979年   9篇
  1976年   7篇
  1974年   6篇
  1973年   6篇
  1972年   7篇
  1971年   8篇
  1970年   7篇
排序方式: 共有1975条查询结果,搜索用时 93 毫秒
1.
2.
3.
The need for selection of the optimal material for the manufacturing of cardio-patches can be resolved by the use of cryostored autologous pericardial tissue. This short communication is a concise fragment of a large-scale research and demonstrates only the efficiency of cell culturing before and after pericardial preservation in the low temperature conditions.  相似文献   
4.
The contribution of mismatch repair to genetic recombination in T4 phage has been evaluated by three independent approaches: (1) testing for non-additivity of recombinant frequencies; (2) measurements of double exchange frequencies in three-factor crosses: (3) comparisons of recombination abilities of mutations occupying the same site. Quantitative agreement among the results of these approaches suggests that within distances much less than the mean length of hybrid regions, mismatch repair accounts perfectly for high negative interference as measured in three-factor crosses and as manifested by non-additivity in two-factor crosses. The mismatch repair mechanism readily recognizes only particular mismatches, the repair frequency being dependent on the base sequence in both strands of the mismatched region.  相似文献   
5.
A continuous-flow NMR culture system for mammalian cells has been developed on which 31P-NMR experiments under complete and strictly physiologic conditions have been performed. Observations on the response of the cellular metabolism to stresses such as starvation, low temperature and changes in environmental pH monitored by 31P-NMR are reported. The response of the intracellular pH relative to the external pH of the growth medium is studied. We find that under the experimental conditions used there exists a ΔpH varying between less than 0.2 and more than 0.6 pH units. These results are compatible with those obtained using other techniques.  相似文献   
6.
Phosphorylation of duck gizzard caldesmon by Ca2+/phospholipid-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase and casein kinase II has been investigated. The Ca2+/phospholipid-dependent protein kinase incorporates more than 3 mol phosphate per mol (140 kDa) caldesmon. All phosphorylation sites are localized in the actin- and calmodulin-binding peptide (40-45 kDa) supposed to be a part of the C-terminal domain of caldesmon. Casein kinase II phosphorylates only one site located in a short (25-27 kDa) peptide, presumably in the caldesmon N-terminal domain. The Ca2+/calmodulin-dependent protein kinase phosphorylates two sites located in the N- and C-terminal domains of caldesmon.  相似文献   
7.
Regularities attending the change in the lumen diameter and the area of the endothelial cells were studied in the capillaries of the rat parotid gland during the secretory cycle under conditions of circulatory ischemia. The mean lumen diameter and the area of endothelial cells failed to change during the secretory cycle and during the occlusion of the carotid artery. It is thus supposed that enhanced capillary blood flow during the discharge of saliva could be explained by the growing number of the functioning capillaries.  相似文献   
8.
The structural correlates of the cell responses in subnuclei of the hypothalamic paraventricular nuclei (PVN) in fasting and carbohydrate loaded adult male rats were studied using light microscopic morphometric methods. The data obtained revealed difference in responsiveness of the subnuclei studied to alternative shifts in the carbohydrate homeostasis: histophysiological features in five of ten cell-divisions, distinguished in the rat RVN, demonstrated their dependence on impaired carbohydrate homeostasis.  相似文献   
9.
Summary Purified tumour cells and normal mucosa cells from fresh human colorectal cancer resection specimens, and T-cell-enriched autologous peripheral blood lymphocytes, were mixed in short-term (6 day) mixed lymphocytetumour cell (MLTC) microcultures. Lymphocyte stimulation was measured by 3H-thymidine uptake, and a stimulation index (SI=[lymphocytes vs tumour cells (cpm)–tumour cells (cpm)]/[lymphocytes (cpm)])>3 was regarded as significant. Significant lymphocyte reactivity was found in 10/15 patients with colon carcinoma. However, 1 patient with autologous tumour reactivity, also showed significant stimulation against autologous normal mucosa cells, suggesting tumour-associated reactivity. Maximum stimulation occurred most frequently at a lymphocyte:tumour cell ratio of 2:1 and with nylon wool-passaged lymphocytes.Project was supported by a grant from the Cancer Research CampaignSupported by New South Wales Cancer Council Fellowship  相似文献   
10.
Oleg Pekarsky 《ZooKeys》2012,(242):43-50
A new species of the genus Schrankia Hübner, 1825, S. pelicano sp. n. is described from Sichuan, China. A diagnostic comparison is made with Schrankia taenialis (Hübner, [1809]) and Schrankia separatalis (Herz, 1904); illustrations of the male holotype and its genitalia are provided. A checklist of the genus with synonyms is given.  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