全文获取类型
收费全文 | 241746篇 |
免费 | 4910篇 |
国内免费 | 684篇 |
专业分类
电工技术 | 4353篇 |
综合类 | 162篇 |
化学工业 | 35772篇 |
金属工艺 | 8350篇 |
机械仪表 | 6324篇 |
建筑科学 | 5431篇 |
矿业工程 | 837篇 |
能源动力 | 5903篇 |
轻工业 | 22021篇 |
水利工程 | 2113篇 |
石油天然气 | 2997篇 |
武器工业 | 14篇 |
无线电 | 29077篇 |
一般工业技术 | 44358篇 |
冶金工业 | 54844篇 |
原子能技术 | 3811篇 |
自动化技术 | 20973篇 |
出版年
2021年 | 2470篇 |
2020年 | 1824篇 |
2019年 | 2360篇 |
2018年 | 3689篇 |
2017年 | 3659篇 |
2016年 | 3834篇 |
2015年 | 2773篇 |
2014年 | 4274篇 |
2013年 | 11232篇 |
2012年 | 7047篇 |
2011年 | 8890篇 |
2010年 | 7090篇 |
2009年 | 7866篇 |
2008年 | 8042篇 |
2007年 | 7880篇 |
2006年 | 6931篇 |
2005年 | 6475篇 |
2004年 | 6296篇 |
2003年 | 6047篇 |
2002年 | 5782篇 |
2001年 | 5913篇 |
2000年 | 5525篇 |
1999年 | 6099篇 |
1998年 | 18544篇 |
1997年 | 12283篇 |
1996年 | 9012篇 |
1995年 | 6521篇 |
1994年 | 5618篇 |
1993年 | 5703篇 |
1992年 | 3604篇 |
1991年 | 3493篇 |
1990年 | 3385篇 |
1989年 | 3206篇 |
1988年 | 2954篇 |
1987年 | 2391篇 |
1986年 | 2427篇 |
1985年 | 2797篇 |
1984年 | 2452篇 |
1983年 | 2162篇 |
1982年 | 2031篇 |
1981年 | 2185篇 |
1980年 | 1951篇 |
1979年 | 1730篇 |
1978年 | 1736篇 |
1977年 | 2342篇 |
1976年 | 3394篇 |
1975年 | 1488篇 |
1974年 | 1414篇 |
1973年 | 1384篇 |
1972年 | 1143篇 |
排序方式: 共有10000条查询结果,搜索用时 214 毫秒
71.
In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria 下载免费PDF全文
Su Chul Jang Sae Rom Kim Yae Jin Yoon Kyong‐Su Park Ji Hyun Kim Jaewook Lee Oh Youn Kim Eun‐Jeong Choi Dae‐Kyum Kim Dong‐Sic Choi Yoon‐Keun Kim Jaesung Park Dolores Di Vizio Yong Song Gho 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(4):456-461
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
72.
73.
74.
75.
76.
77.
ABSTRACTIn this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory. 相似文献
78.
Akopdzhanyan T. G. Chemagina E. A. Borovinskaya I. P. 《Russian Journal of Non-Ferrous Metals》2020,61(6):686-690
Russian Journal of Non-Ferrous Metals - The synthesis and sintering of the (AlN)x(SiC)1 – x solid solution have been studied under conditions of self-propagating high-temperature synthesis... 相似文献
79.
ABSTRACTThis paper presents an empirical assessment of four state-of-the-art risk-averse approaches to deal with the capacitated lot-sizing problem under stochastic demand. We analyse two mean-risk models based on the semideviation and on the conditional value-at-risk risk measures, and alternate first and second-order stochastic dominance approaches. The extensive computational experiments based on different instances characteristics and on a case-study suggest that CVaR exhibits a good trade-off between risk and performance, followed by the semideviation and first-order stochastic dominance approach. For all approaches, enforcing risk-aversion helps to reduce the cost-standard deviation substantially, which is usually accomplished via increasing production rates. Overall, we can say that very risk-averse decision-makers would be willing to pay an increased price to have a much less risky solution given by CVaR . In less risk-averse settings, though, semideviation and first-order stochastic dominance can be appealing alternatives to provide significantly more stable production planning costs with a marginal increase of the expected costs. 相似文献
80.
Zavadiuk S.V. Loboda P.I. Soloviova T.O. Trosnikova I.Iu. Karasevska O.P. 《Powder Metallurgy and Metal Ceramics》2020,59(1-2):22-28
Powder Metallurgy and Metal Ceramics - The properties of sintered and heat-treated steels produced from the Catamold 8740 material by powder injection molding were examined. Parts made of the... 相似文献