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   87977篇
  免费   5849篇
  国内免费   2026篇
电工技术   2586篇
技术理论   1篇
综合类   2264篇
化学工业   15960篇
金属工艺   3738篇
机械仪表   4941篇
建筑科学   3448篇
矿业工程   788篇
能源动力   3142篇
轻工业   7069篇
水利工程   980篇
石油天然气   1376篇
武器工业   271篇
无线电   14091篇
一般工业技术   15159篇
冶金工业   7284篇
原子能技术   1062篇
自动化技术   11692篇
  2024年   193篇
  2023年   978篇
  2022年   1768篇
  2021年   2664篇
  2020年   1987篇
  2019年   1837篇
  2018年   2308篇
  2017年   2374篇
  2016年   2725篇
  2015年   2583篇
  2014年   3614篇
  2013年   5607篇
  2012年   5473篇
  2011年   6273篇
  2010年   5162篇
  2009年   5289篇
  2008年   4891篇
  2007年   4451篇
  2006年   3987篇
  2005年   3352篇
  2004年   3015篇
  2003年   2814篇
  2002年   2798篇
  2001年   2349篇
  2000年   1858篇
  1999年   1650篇
  1998年   2603篇
  1997年   1743篇
  1996年   1473篇
  1995年   1154篇
  1994年   883篇
  1993年   794篇
  1992年   601篇
  1991年   563篇
  1990年   472篇
  1989年   469篇
  1988年   349篇
  1987年   305篇
  1986年   277篇
  1985年   246篇
  1984年   219篇
  1983年   172篇
  1982年   161篇
  1981年   140篇
  1980年   141篇
  1979年   113篇
  1978年   99篇
  1977年   133篇
  1976年   168篇
  1974年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Journal of Mechanical Science and Technology - This study delivers equations useful for low-height pleated fibrous filter design: two pressure drop equations and one set of optimum design equations...  相似文献   
33.
This article focuses on the consensus problem of leader-following fractional-order multi-agent systems (MASs) with general linear and Lipschitz nonlinear dynamics. First, the distributed adaptive protocols for linear and nonlinear fractional-order MASs are constructed, respectively. We allow the control coupling gains to be time varying for each agent. Moreover, the adaptive modification schemes for the control gain are designed, which renders smaller control gains and thus requires smaller amplitude on the control input without sacrificing consensus convergence. Second, based on fractional-order Lyapunov stability theorem and Barbalat's lemma, two novel sufficient conditions in terms of linear matrix inequalities are provided to ensure that the leader-following consensus can be obtained in the case for any undirected connected communication graph. Furthermore, we show that the proposed algorithm also works for consensus of agents with intrinsic Lipschitz nonlinear dynamics. As a result, the proposed framework requires no global information and thus can be implemented in a fully distributed manner. Finally, the numerical simulations are given to demonstrate the effectiveness of obtained the theoretical results.  相似文献   
34.
35.
Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo.  相似文献   
36.
37.
38.
Unreliable mobility values, and particularly greatly overestimated values and severely distorted temperature dependences, have recently hampered the development of the organic transistor field. Given that organic field‐effect transistors (OFETs) have been routinely used to evaluate mobility, precise parameter extraction using the electrical properties of OFETs is thus of primary importance. This review examines the origins of the various mobilities that must be determined for OFET applications, the relevant extraction methods, and the data selection limitations, which help in avoiding conceptual errors during mobility extraction. For increased precision, the review also discusses device fabrication considerations, calibration of both the specific gate‐dielectric capacitance and the threshold voltage, the contact effects, and the bias and temperature dependences, which must actually be handled with great care but have mostly been overlooked to date. This review serves as a systematic overview of the OFET mobility extraction process to ensure high precision and will also aid in improving future research.  相似文献   
39.
40.
The cover image is based on the Research Article V2O5/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification by Mohan, H et al., DOI: 10.1002/jctb.6238 .

  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