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   289549篇
  免费   5497篇
  国内免费   1857篇
电工技术   5742篇
技术理论   5篇
综合类   1175篇
化学工业   47968篇
金属工艺   11816篇
机械仪表   8300篇
建筑科学   8284篇
矿业工程   1899篇
能源动力   6553篇
轻工业   28118篇
水利工程   3178篇
石油天然气   6151篇
武器工业   245篇
无线电   29712篇
一般工业技术   53719篇
冶金工业   52953篇
原子能技术   5891篇
自动化技术   25194篇
  2021年   2794篇
  2020年   1952篇
  2019年   2460篇
  2018年   3812篇
  2017年   3790篇
  2016年   4139篇
  2015年   3195篇
  2014年   5235篇
  2013年   13294篇
  2012年   8785篇
  2011年   11583篇
  2010年   9158篇
  2009年   9802篇
  2008年   10737篇
  2007年   10886篇
  2006年   9539篇
  2005年   8428篇
  2004年   7565篇
  2003年   7100篇
  2002年   7128篇
  2001年   6896篇
  2000年   6461篇
  1999年   6389篇
  1998年   13407篇
  1997年   9986篇
  1996年   7810篇
  1995年   6004篇
  1994年   5556篇
  1993年   5431篇
  1992年   4388篇
  1991年   4034篇
  1990年   4204篇
  1989年   4141篇
  1988年   3877篇
  1987年   3393篇
  1986年   3382篇
  1985年   3876篇
  1984年   3758篇
  1983年   3462篇
  1982年   3104篇
  1981年   3300篇
  1980年   2949篇
  1979年   3167篇
  1978年   3025篇
  1977年   3110篇
  1976年   3941篇
  1975年   2730篇
  1974年   2502篇
  1973年   2571篇
  1972年   2125篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Vertical arrays of nanostructures (NSs) are emerging as promising platforms for probing and manipulating live mammalian cells. The broad range of applications requires different types of interfaces, but cell settling on NS arrays is not yet fully controlled and understood. Cells are both seen to deform completely into NS arrays and to stay suspended like tiny fakirs, which have hitherto been explained with differences in NS spacing or density. Here, a better understanding of this phenomenon is provided by using a model that takes into account the extreme membrane deformation needed for a cell to settle into a NS array. It is shown that, in addition to the NS density, cell settling depends strongly on the dimensions of the single NS, and that the settling can be predicted for a given NS array geometry. The predictive power of the model is confirmed by experiments and good agreement with cases from the literature. Furthermore, the influence of cell‐related parameters is evaluated theoretically and a generic method of tuning cell settling through surface coating is demonstrated experimentally. These findings allow a more rational design of NS arrays for the numerous exciting biological applications where the mode of cell settling is crucial.  相似文献   
52.
53.
54.
  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   
55.
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   
56.
57.
The machining of metal surfaces and the application of functional coatings by means of a flexible tool (a rotating wire brush) is considered. Frictional cladding may be applied on metal-cutting machines by means of simple attachments or manual angle grinders.  相似文献   
58.
59.
60.
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   
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