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   5236篇
  免费   40篇
  国内免费   13篇
电工技术   26篇
综合类   15篇
化学工业   161篇
金属工艺   38篇
机械仪表   41篇
建筑科学   45篇
矿业工程   15篇
能源动力   24篇
轻工业   182篇
水利工程   9篇
石油天然气   8篇
武器工业   1篇
无线电   115篇
一般工业技术   176篇
冶金工业   4249篇
原子能技术   47篇
自动化技术   137篇
  2022年   13篇
  2021年   22篇
  2020年   13篇
  2019年   21篇
  2018年   15篇
  2017年   13篇
  2016年   13篇
  2015年   17篇
  2014年   23篇
  2013年   66篇
  2012年   39篇
  2011年   57篇
  2010年   53篇
  2009年   45篇
  2008年   51篇
  2007年   36篇
  2006年   34篇
  2005年   50篇
  2004年   40篇
  2003年   33篇
  2002年   41篇
  2001年   37篇
  2000年   31篇
  1999年   147篇
  1998年   1342篇
  1997年   784篇
  1996年   466篇
  1995年   285篇
  1994年   240篇
  1993年   244篇
  1992年   56篇
  1991年   43篇
  1990年   67篇
  1989年   63篇
  1988年   71篇
  1987年   51篇
  1986年   53篇
  1985年   66篇
  1984年   8篇
  1983年   24篇
  1982年   27篇
  1981年   33篇
  1980年   39篇
  1979年   20篇
  1978年   28篇
  1977年   102篇
  1976年   176篇
  1975年   21篇
  1972年   7篇
  1971年   8篇
排序方式: 共有5289条查询结果,搜索用时 15 毫秒
61.
A new algorithm for stereo matching is presented, based on the idea of imposing a limit on disparity gradients allowed in the matched image. The matching problem will be expressed as one of maximizing a certain function, subject to constraints. Standard methods from optimization theory may then be used to find a solution.  相似文献   
62.
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   
63.
64.
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   
65.
66.
67.
A previously unreported xenon-neutral laser line at 4.02 μ has been observed in high-pressure He-Xe mixtures excited by a pulsed electrical discharge.  相似文献   
68.
69.
70.
UV-curable formulations do not UV cure when hydroxybenzophenone or hydroxyphenylbenzotriazole UV screens are added to them. Reaction of these UV screens with alkyl or aryl isocyanates gives urethane derivatives in high yields. These derivatives do not impede UV cures when they are incorporated in UV-curable formulations at relatively high levels (3%–5%). After completion of the UV cure, the urethane derivatives are catalytically decomposed by heating to regenerate the corresponding UV screen within the cured coating.  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