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   4849822篇
  免费   316272篇
  国内免费   184841篇
电工技术   260225篇
技术理论   125篇
综合类   263986篇
化学工业   709858篇
金属工艺   231781篇
机械仪表   258716篇
建筑科学   270307篇
矿业工程   113817篇
能源动力   135913篇
轻工业   402575篇
水利工程   100302篇
石油天然气   143597篇
武器工业   35593篇
无线电   518627篇
一般工业技术   591588篇
冶金工业   570863篇
原子能技术   63866篇
自动化技术   679196篇
  2024年   14704篇
  2023年   45881篇
  2022年   107656篇
  2021年   146876篇
  2020年   107479篇
  2019年   87391篇
  2018年   104597篇
  2017年   116563篇
  2016年   107137篇
  2015年   128601篇
  2014年   174817篇
  2013年   274813篇
  2012年   281714篇
  2011年   320511篇
  2010年   287256篇
  2009年   287422篇
  2008年   294108篇
  2007年   285392篇
  2006年   258852篇
  2005年   215974篇
  2004年   153965篇
  2003年   118219篇
  2002年   110854篇
  2001年   101779篇
  2000年   98846篇
  1999年   81395篇
  1998年   142736篇
  1997年   100770篇
  1996年   85447篇
  1995年   66994篇
  1994年   58279篇
  1993年   49964篇
  1992年   33319篇
  1991年   30088篇
  1990年   29898篇
  1989年   28987篇
  1988年   26856篇
  1987年   24494篇
  1986年   23805篇
  1985年   25551篇
  1984年   22172篇
  1983年   20373篇
  1982年   19186篇
  1981年   19543篇
  1980年   18776篇
  1979年   16825篇
  1978年   16239篇
  1977年   22921篇
  1976年   33658篇
  1975年   14037篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
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   
112.
针对基站柜式空调耗电量大的问题,创造性地使用基站分布式冷却的方式,达到精确送风,节能高效的目的.在应用实践中检验了分布式冷却系统实际节能量和应用效果,总结出分布式冷却系统应用场景和范围,为更大范围推广应用DCS分布式冷却系统提供实践依据.  相似文献   
113.
114.
115.
116.
117.
Tuna cooking juice is a by‐product from the tuna canning industry. In this study, tuna cooking juice was hydrolysed by proteases extracted from the spleen. Tuna cooking juice showed the highest ACE inhibitory and Ca‐binding activities after hydrolysis for 270 and 180 min, respectively. The hydrolysate was further fractionated by ultrafiltration. The permeate exhibited highest ACE inhibitory and Ca‐binding activities when passed through 1 and 5 kDa cut‐off membranes, respectively. Gel filtration chromatography was used to determine the MW of bioactive peptides that exhibited highest ACE inhibitory and Ca‐binding activities. Those peptides that exhibited highest ACE inhibitory and Ca‐binding activities were the MW range of 238–829 Da and 1355–1880 Da, respectively. These results suggest that the tuna cooking juice and the spleen protease extract are a potential source of bioactive peptides that can be utilised as bioactive ingredients in functional food and nutraceuticals.  相似文献   
118.
陈国亮  李宏  朱旭 《纺织器材》2015,42(1):61-62
为了解决钢丝圈挂花问题,阐述了LH001新型钢丝圈清洁器的特点和应用效果;通过试验说明使用新型钢丝圈清洁器断头率低,基本无挂花,纺纱效果好。指出:新型钢丝圈清洁器是普通钢丝圈清洁器的更新换代产品,值得推广。  相似文献   
119.
120.
The development of a sustainable energy system throughout an enterprise is a complex task, which requires an agile holistic approach. Such an approach needs to include a variety of objectives including energy strategy formation and strategic decision-making, which are directly related to the analysis and management of the main areas of sustainable development:The economic, technological, environmental, and social. These multidimensional requirements of sustainability are often difficult to achieve within the enterprise, because these aspects are interrelated and influenced by various internal and external environment factors. This paper first reviews the main challenges for an energy system, and then demonstrates how a strategic agile enterprise architecture driven approach could effectively guide the sustainable energy system development. The study presented in this paper provides a holistic approach that contributes to the advancement and usage of literature dealing with issues of sustainable energy system development and agile enterprise architecture, which has not been discussed before to any great extent.  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