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   380182篇
  免费   4141篇
  国内免费   764篇
电工技术   7828篇
综合类   644篇
化学工业   55630篇
金属工艺   16329篇
机械仪表   14422篇
建筑科学   9196篇
矿业工程   1600篇
能源动力   9127篇
轻工业   32157篇
水利工程   3589篇
石油天然气   4941篇
武器工业   8篇
无线电   46452篇
一般工业技术   76822篇
冶金工业   62117篇
原子能技术   6465篇
自动化技术   37760篇
  2021年   2290篇
  2019年   2146篇
  2018年   11650篇
  2017年   12128篇
  2016年   8050篇
  2015年   3081篇
  2014年   4541篇
  2013年   14358篇
  2012年   9902篇
  2011年   18150篇
  2010年   15662篇
  2009年   15694篇
  2008年   15889篇
  2007年   17838篇
  2006年   8578篇
  2005年   11474篇
  2004年   9669篇
  2003年   9052篇
  2002年   7958篇
  2001年   7610篇
  2000年   7345篇
  1999年   7568篇
  1998年   17668篇
  1997年   12839篇
  1996年   10117篇
  1995年   7891篇
  1994年   7236篇
  1993年   6925篇
  1992年   5300篇
  1991年   5089篇
  1990年   4936篇
  1989年   4785篇
  1988年   4679篇
  1987年   3889篇
  1986年   4008篇
  1985年   4719篇
  1984年   4282篇
  1983年   4027篇
  1982年   3604篇
  1981年   3765篇
  1980年   3459篇
  1979年   3421篇
  1978年   3226篇
  1977年   3817篇
  1976年   4852篇
  1975年   2784篇
  1974年   2662篇
  1973年   2677篇
  1972年   2215篇
  1971年   1964篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
The authors have determined the causes of drop in performance of induced block caving using fans of blastholes 105 mm in diameter and single blastholes 250 mm in diameter, as well as the sources of increased drilling cost and expansion of start-up time of production blocks in Abakan underground mine. Alternatives of improvement in drilling efficiency under current conditions are discussed.  相似文献   
64.
65.
66.
Wireless Personal Communications - Cloud computing is a growing technology where lot of heterogeneous resources are available and large amount of requests are submitted by the customers...  相似文献   
67.
The degree of rate control (DRC) quantitatively identifies the kinetically relevant (sometimes known as rate-limiting) steps of a complex reaction network. This concept relies on derivatives which are commonly implemented numerically, for example, with finite differences (FDs). Numerical derivatives are tedious to implement, and can be problematic, and unstable or unreliable. In this study, we demonstrate the use of automatic differentiation (AD) in the evaluation of the DRC. AD libraries are increasingly available through modern machine learning frameworks. Compared with the FDs, AD provides solutions with higher accuracy with lower computational cost. We demonstrate applications in steady-state and transient kinetics. Furthermore, we illustrate a hybrid local-global sensitivity analysis method, the distributed evaluation of local sensitivity analysis, to assess the importance of kinetic parameters over an uncertain space. This method also benefits from AD to obtain high-quality results efficiently.  相似文献   
68.
Wireless Personal Communications - The majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the...  相似文献   
69.
Neutrophils readily infiltrate infection foci, phagocytose and usually destroy microbes. In tuberculosis (TB), a chronic pulmonary infection caused by Mycobacterium tuberculosis (Mtb), neutrophils harbor bacilli, are abundant in tissue lesions, and their abundances in blood correlate with poor disease outcomes in patients. The biology of these innate immune cells in TB is complex. Neutrophils have been assigned host-beneficial as well as deleterious roles. The short lifespan of neutrophils purified from blood poses challenges to cell biology studies, leaving intracellular biological processes and the precise consequences of Mtb–neutrophil interactions ill-defined. The phenotypic heterogeneity of neutrophils, and their propensity to engage in cellular cross-talk and to exert various functions during homeostasis and disease, have recently been reported, and such observations are newly emerging in TB. Here, we review the interactions of neutrophils with Mtb, including subcellular events and cell fate upon infection, and summarize the cross-talks between neutrophils and lung-residing and -recruited cells. We highlight the roles of neutrophils in TB pathophysiology, discussing recent findings from distinct models of pulmonary TB, and emphasize technical advances that could facilitate the discovery of novel neutrophil-related disease mechanisms and enrich our knowledge of TB pathogenesis.  相似文献   
70.
A technology for slag formation in the ladle–furnace unit is considered; the slag is based on the CaO–SiO2–MgO–Al2O3–B2O3 system. This technology permits both microalloying of the steel with boron (reduced from the oxide phase) and desulfurization of the steel. The resulting boron content in the steel is 0.001–0.008%; the sulfur content in low-alloy steel and pipe steel is low (0.004–0.010%); and the consumption of manganese ferroalloys is reduced to 0.5 kg/t for 08кп steel and 1.4 kg/t for 09Г2C steel. In addition, the proposed technology increases the strength of the rolled steel, without loss in its plasticity; and reduces the environmental impact thanks to the replacement of fluorspar by colemanite.  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