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   3964篇
  免费   19篇
  国内免费   12篇
电工技术   12篇
综合类   15篇
化学工业   38篇
金属工艺   9篇
机械仪表   19篇
建筑科学   24篇
矿业工程   13篇
能源动力   4篇
轻工业   55篇
水利工程   4篇
石油天然气   6篇
武器工业   1篇
无线电   24篇
一般工业技术   20篇
冶金工业   3704篇
原子能技术   10篇
自动化技术   37篇
  2023年   3篇
  2022年   8篇
  2021年   15篇
  2020年   8篇
  2019年   11篇
  2018年   4篇
  2017年   2篇
  2016年   7篇
  2015年   9篇
  2014年   12篇
  2013年   23篇
  2012年   14篇
  2011年   18篇
  2010年   18篇
  2009年   15篇
  2008年   16篇
  2007年   13篇
  2006年   12篇
  2005年   24篇
  2004年   13篇
  2003年   9篇
  2002年   13篇
  2001年   5篇
  2000年   2篇
  1999年   112篇
  1998年   1217篇
  1997年   706篇
  1996年   412篇
  1995年   248篇
  1994年   195篇
  1993年   210篇
  1992年   38篇
  1991年   24篇
  1990年   42篇
  1989年   36篇
  1988年   47篇
  1987年   37篇
  1986年   35篇
  1985年   35篇
  1983年   4篇
  1982年   14篇
  1981年   20篇
  1980年   27篇
  1979年   2篇
  1978年   12篇
  1977年   82篇
  1976年   148篇
  1975年   12篇
  1963年   1篇
  1955年   3篇
排序方式: 共有3995条查询结果,搜索用时 0 毫秒
51.
Cell-cell and cell-extracellular matrix interactions are fundamental processes involved in cell migration and tissue remodeling. Both the cyclic regeneration of the human endometrium during the menstrual cycle as well as the process of embryo implantation involve such dynamic interactions. It has become quite clear that integrin adhesion molecules expressed on the surface of cells play critical roles in the transmission of signals from the extracellular milieu to the cells. It is these signals that presumably regulate the behavior of these cells during major morphogenetic processes. In recent years, work in human endometrium and trophoblasts has uncovered both the regulated and constitutive expression of integrin subunits and their extracellular matrix ligands in these tissues. In addition, attempts have been made to correlate pathological states related to either infertility or abnormal pregnancy to the aberrant expression of several of these integrins. The purpose of the present review is to describe briefly our present state of knowledge of the expression of integrins in human endometrium and trophoblasts and provide the reader with the necessary background needed to understand, at the cellular and molecular levels, processes in reproduction such as embryo implantation.  相似文献   
52.
53.
OBJECTIVE: To assess the effect of mixing the insulin analog lispro (Humalog) with NPH (Humulin I) before injection on lispro's fast, short action profile. RESEARCH DESIGN AND METHODS: A total of 12 healthy volunteers received subcutaneous abdominal injections of 0.1 U/kg regular insulin and 0.2 U/kg NPH insulin as follows: lispro and NPH injected separately (treatment group A), lispro and NPH mixed in the syringe up to 2 min before single injection (treatment group B), and human regular insulin and NPH mixed and injected as in group B (treatment group C), on separate occasions, in random order. Plasma glucose was maintained for 12 h by intravenous 20% glucose. Pharmacokinetic and pharmacodynamic parameters were compared by analysis of variance for repeated measures. RESULTS: Peak plasma insulin levels (2.6 +/- 0.8 vs. 2.2 +/- 0.6 vs. 1.9 +/- 0.6 ng/ml, P = 0.075), total glucose infused (121.5 +/- 32.8 vs. 135.0 +/- 49.0 vs. 117.3 +/- 39.9 mg.kg-1.min-1, P = 0.53), and maximum glucose infusion rate (GIRmax) (8.3 +/- 0.9 vs. 8.0 +/- 1.7 vs. 7.1 +/- 2.4 mg.kg-1.min-1, P = 0.65) were not significantly different between treatments. The times until peak insulin concentrations were similar in treatment groups A and B, but significantly shorter than in treatment group C (0.9 +/- 0.3 and 1.2 +/- 0.2 vs. 2.0 +/- 0.4 h, respectively, P = 0.042). The times until GIRmax were also not different (113.9 +/- 41 and 122.0 +/- 45 vs. 209.0 +/- 51.3 min, respectively, P = 0.002). The glucose infusion rate (GIR) then fell to 50% GIRmax more quickly in treatment groups A and B than in treatment group C (239.9 +/- 40.5 vs. 292.4 +/- 133.3 vs. 399.5 +/- 78.3, respectively, P = 0.005). CONCLUSIONS: The action profile of lispro is not attenuated by mixing lispro with NPH in the syringe immediately before injection. The advantages are available to those individuals who need to combine types of insulin before injection to achieve optimal diabetes control.  相似文献   
54.
55.
56.
57.
58.
59.
Multifocal Best's vitelliform dystrophy   总被引:3,自引:0,他引:3  
Three members of a family had multifocal, macular and extramacular--Best's vitelliform dystrophy. The lesion in one patient was observed over a ten-year period. A striking symmetry of locale and evolution of these lesions is noted between the eyes of a patient as well as among the three members of the family. The pseudohypopyon of the vitelliform cyst and the vitelliform deposits showed fluorescence before fluorescein injection. A hypofluorescent halo surrounded most lesions.  相似文献   
60.
本文叙述了用n-p散射方法刻度快中子探测器效率的基本原理、实验方法和测量结果。400 keV氘束轰击T-Ti靶,由T(d,n)~He反应得到15.2 MeV的中子,散射体是一个圆柱塑料闪烁体(φ2.2×3cm),飞行距离2m,时间分辨率约1.5ns,效率测量的能区范围为1—14MeV,对多次散射和几何条件作了修正,总的误差约2%。  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