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   616733篇
  免费   9769篇
  国内免费   1840篇
电工技术   11155篇
综合类   822篇
化学工业   95901篇
金属工艺   22278篇
机械仪表   18058篇
建筑科学   16521篇
矿业工程   2257篇
能源动力   15570篇
轻工业   63339篇
水利工程   5486篇
石油天然气   6884篇
武器工业   51篇
无线电   73859篇
一般工业技术   113216篇
冶金工业   116342篇
原子能技术   10569篇
自动化技术   56034篇
  2021年   5035篇
  2019年   4650篇
  2018年   7375篇
  2017年   7429篇
  2016年   7921篇
  2015年   5767篇
  2014年   9504篇
  2013年   28310篇
  2012年   15815篇
  2011年   22156篇
  2010年   17189篇
  2009年   19413篇
  2008年   20355篇
  2007年   20694篇
  2006年   18360篇
  2005年   16875篇
  2004年   16386篇
  2003年   15907篇
  2002年   15606篇
  2001年   15471篇
  2000年   14398篇
  1999年   14804篇
  1998年   34860篇
  1997年   25205篇
  1996年   19683篇
  1995年   15248篇
  1994年   13510篇
  1993年   13121篇
  1992年   9980篇
  1991年   9447篇
  1990年   9286篇
  1989年   8863篇
  1988年   8473篇
  1987年   7222篇
  1986年   7228篇
  1985年   8667篇
  1984年   8099篇
  1983年   7124篇
  1982年   6721篇
  1981年   6745篇
  1980年   6441篇
  1979年   6192篇
  1978年   5993篇
  1977年   7006篇
  1976年   9383篇
  1975年   5073篇
  1974年   4855篇
  1973年   4872篇
  1972年   3962篇
  1971年   3537篇
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
101.
102.
Ischemic and hemorrhagic strokes are associated with severe functional disability and high mortality. Except for recombinant tissue plasminogen activator, therapies targeting the underlying pathophysiology of central nervous system (CNS) ischemia and hemorrhage are strikingly lacking. Sur1-regulated channels play essential roles in necrotic cell death and cerebral edema following ischemic insults, and in neuroinflammation after hemorrhagic injuries. Inhibiting endothelial, neuronal, astrocytic and oligodendroglial sulfonylurea receptor 1–transient receptor potential melastatin 4 (Sur1–Trpm4) channels and, in some cases, microglial KATP (Sur1–Kir6.2) channels, with glibenclamide is protective in a variety of contexts. Robust preclinical studies have shown that glibenclamide and other sulfonylurea agents reduce infarct volumes, edema and hemorrhagic conversion, and improve outcomes in rodent models of ischemic stroke. Retrospective studies suggest that diabetic patients on sulfonylurea drugs at stroke presentation fare better if they continue on drug. Additional laboratory investigations have implicated Sur1 in the pathophysiology of hemorrhagic CNS insults. In clinically relevant models of subarachnoid hemorrhage, glibenclamide reduces adverse neuroinflammatory and behavioral outcomes. Here, we provide an overview of the preclinical studies of glibenclamide therapy for CNS ischemia and hemorrhage, discuss the available data from clinical investigations, and conclude with promising preclinical results that suggest glibenclamide may be an effective therapeutic option for ischemic and hemorrhagic stroke.  相似文献   
103.
104.
ARIMA is seldom used in supply chains in practice. There are several reasons, not the least of which is the small sample size of available data, which restricts the usage of the model. Keeping in mind this restriction, we discuss in this paper a state-space ARIMA model with a single source of error and show how it can be efficiently used in the supply-chain context, especially in cases when only two seasonal cycles of data are available. We propose a new order selection algorithm for the model and compare its performance with the conventional ARIMA on real data. We show that the proposed model performs well in terms of both accuracy and computational time in comparison with other ARIMA implementations, which makes it efficient in the supply-chain context.  相似文献   
105.
The environmental performance of 316L grade stainless steel, in the form of tensile specimens containing a single corrosion pit with various aspect ratios, under cyclic loading in aerated chloride solutions is investigated in this study. Results from environmental tests were compared and contrasted with those obtained using finite element analysis (FEA). Fractography of the failed specimens obtained from experiments revealed that fatigue crack initiation took place at the base of the shallow pit. The crack initiation shifted towards the shoulder and the mouth of the pit for pits of increasing depth. This process is well predicted by FEA, as the strain contour maps show that strain is the highest around the centric strip of the pit. However, for shallow pits, local strain is uniformly distributed around that strip but begins to concentrate more towards the shoulder and the mouth region for increasingly deep pits.  相似文献   
106.
107.
108.
109.
110.
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