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   579660篇
  免费   24538篇
  国内免费   11984篇
电工技术   21925篇
技术理论   4篇
综合类   14575篇
化学工业   85322篇
金属工艺   24607篇
机械仪表   23334篇
建筑科学   25880篇
矿业工程   6526篇
能源动力   16188篇
轻工业   56697篇
水利工程   7544篇
石油天然气   10165篇
武器工业   2022篇
无线电   75749篇
一般工业技术   93161篇
冶金工业   81587篇
原子能技术   7484篇
自动化技术   63412篇
  2023年   3472篇
  2022年   7009篇
  2021年   10264篇
  2020年   7507篇
  2019年   6826篇
  2018年   8744篇
  2017年   9775篇
  2016年   9184篇
  2015年   11022篇
  2014年   15294篇
  2013年   30568篇
  2012年   23401篇
  2011年   28391篇
  2010年   24036篇
  2009年   24870篇
  2008年   25739篇
  2007年   25444篇
  2006年   22893篇
  2005年   19869篇
  2004年   17071篇
  2003年   15933篇
  2002年   15383篇
  2001年   15084篇
  2000年   13407篇
  1999年   13262篇
  1998年   25576篇
  1997年   18868篇
  1996年   15090篇
  1995年   12006篇
  1994年   10611篇
  1993年   9872篇
  1992年   7539篇
  1991年   7091篇
  1990年   6635篇
  1989年   6314篇
  1988年   6004篇
  1987年   4977篇
  1986年   4920篇
  1985年   6015篇
  1984年   5634篇
  1983年   4855篇
  1982年   4523篇
  1981年   4485篇
  1980年   4249篇
  1979年   4105篇
  1978年   3780篇
  1977年   4557篇
  1976年   6104篇
  1975年   3121篇
  1974年   3014篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
  Qing  Xu  Bin  Yu  Yang  Zhan  Wei  Zhao  Yu  Zheng  Jun  Ji  Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability...  相似文献   
82.
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified.  相似文献   
83.
A tensile properties testing study was conducted to understand the influence of thickness, cross-head speed (speed of testing), gauge length (GL; specimen test length), and sample shape on important tensile properties of polyvinyl alcohol (PVA) nanofiber webs. The effects of each testing parameter on load at break, extension at break, Young's modulus, and tensile stress–strain curve of PVA nanofiber webs are analyzed. The Welch two sample t-tests show the significant difference among tested data. Using interaction plots, two-way analysis of variance, and margin mean plots, the interaction effects among testing parameters have been analyzed. Of all the factors, cross-head speed, the interaction among GL, and sample thickness (GL: Thickness) and the interaction among GL, testing speed and sample thickness (GL: Speed: Thickness) have significant influence on the tensile properties of PVA nanofiber webs. Moreover, the hypothesized model of mechanism of tensile strain–stress curve of PVA nanofiber webs has been proposed. Based on the model, the tensile strain–stress curve can be split into three stages: linear elastic, partial break up, and complete breakage. This study will provide a better understanding of tensile testing parameters' effects and their interaction effects on the tensile properties of nanowebs.  相似文献   
84.
85.
86.
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   
87.
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   
88.
89.
90.
从探讨郭沫若的生平背景入手,介绍了他的翻译成就,并对郭沫若的翻译理论和翻译思想做出了初步的剖析。郭沫若的翻译实践主要可以从郭沫若译著《英诗译稿》和《浮士德》窥见一斑,而郭沫若的翻译理论则可从罗新璋所著的《翻译论集》和方克平所著的《溯洄从美:从批判理论到文学翻译》中探出精髓。对郭沫若翻译实践和理论的研究可以发现郭沫若的"创作论"的地位固然不可撼动,但其中对于创作的维度却并没有提出很好的标准。  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