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   67870篇
  免费   4372篇
  国内免费   899篇
电工技术   1622篇
综合类   1264篇
化学工业   14074篇
金属工艺   2870篇
机械仪表   4091篇
建筑科学   2354篇
矿业工程   406篇
能源动力   2636篇
轻工业   5742篇
水利工程   577篇
石油天然气   752篇
武器工业   92篇
无线电   10156篇
一般工业技术   13002篇
冶金工业   4908篇
原子能技术   918篇
自动化技术   7677篇
  2024年   119篇
  2023年   908篇
  2022年   1504篇
  2021年   2306篇
  2020年   1722篇
  2019年   1693篇
  2018年   2024篇
  2017年   2022篇
  2016年   2390篇
  2015年   1992篇
  2014年   3027篇
  2013年   4194篇
  2012年   4401篇
  2011年   5172篇
  2010年   3948篇
  2009年   4031篇
  2008年   3875篇
  2007年   3182篇
  2006年   2992篇
  2005年   2607篇
  2004年   2192篇
  2003年   1949篇
  2002年   1827篇
  2001年   1563篇
  2000年   1367篇
  1999年   1226篇
  1998年   1934篇
  1997年   1238篇
  1996年   1017篇
  1995年   737篇
  1994年   602篇
  1993年   538篇
  1992年   374篇
  1991年   357篇
  1990年   315篇
  1989年   301篇
  1988年   250篇
  1987年   202篇
  1986年   158篇
  1985年   141篇
  1984年   127篇
  1983年   84篇
  1982年   55篇
  1981年   62篇
  1980年   52篇
  1979年   46篇
  1978年   44篇
  1977年   53篇
  1976年   70篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint.  相似文献   
33.
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.
39.
Machine Learning - We consider the problem of learning a binary classifier from only positive and unlabeled observations (called PU learning). Recent studies in PU learning have shown superior...  相似文献   
40.
Microsystem Technologies - A color-laser printing system consisting of a tandem laser scanning unit uses four laser diodes and a single polygonal mirror (PM) to expose light onto four...  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