首页 | 官方网站   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   85436篇
  免费   7656篇
  国内免费   3905篇
工业技术   96997篇
  2024年   462篇
  2023年   1596篇
  2022年   2794篇
  2021年   3943篇
  2020年   2998篇
  2019年   2447篇
  2018年   2697篇
  2017年   3100篇
  2016年   2794篇
  2015年   3677篇
  2014年   4634篇
  2013年   5679篇
  2012年   5698篇
  2011年   6182篇
  2010年   5115篇
  2009年   4801篇
  2008年   4771篇
  2007年   4474篇
  2006年   4325篇
  2005年   3636篇
  2004年   2482篇
  2003年   2211篇
  2002年   2123篇
  2001年   1855篇
  2000年   1834篇
  1999年   1843篇
  1998年   1555篇
  1997年   1341篇
  1996年   1256篇
  1995年   951篇
  1994年   834篇
  1993年   579篇
  1992年   458篇
  1991年   361篇
  1990年   319篇
  1989年   261篇
  1988年   204篇
  1987年   131篇
  1986年   115篇
  1985年   79篇
  1984年   52篇
  1983年   52篇
  1982年   58篇
  1981年   44篇
  1980年   34篇
  1979年   26篇
  1978年   16篇
  1977年   18篇
  1976年   23篇
  1971年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
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   
4.
Jia  Yuan  Wang  Yangli  Song  Rui  Li  Jiandong 《Multimedia Tools and Applications》2015,74(6):1777-1803
Multimedia Tools and Applications - In Wyner-Ziv (WZ) video coding, decoder side information (SI) takes a key role in a WZ video codec among other building blocks. In this paper, we review the...  相似文献   
5.
6.
In this paper, we study scheduling games under mixed coordination mechanisms on hierarchical machines. The two scheduling policies involved are ‐ and ‐, where ‐ (resp., ‐) policy sequences jobs in nondecreasing order of their hierarchies, and jobs of the same hierarchy in nonincreasing (resp., nondecreasing) order of their processing times. We first show the existence of a Nash equilibrium. Then we present the price of anarchy and the price of stability for the games with social costs of minimizing the makespan and maximizing the minimum machine load. All the bounds given in this paper are tight.  相似文献   
7.
The focused ion beam technique was employed to investigate the atmospheric corrosion morphology of AZ91D. It was found that the α matrix of the alloy was preferentially corroded in the areas adjacent to intermetallic phases. The most interesting finding was that the corrosion products in corrosion cavities were pelletlike, which has never been reported before.  相似文献   
8.
9.
P(DBF-VA)型柴油低温流动性改进剂的研制   总被引:1,自引:1,他引:0  
针对新疆地产柴油蜡含量较高的特点,以游离基聚合法合成了富马酸双链混合酯和醋酸乙烯酯共聚物型[P(DBF-VA)]柴油低温流动改进剂,利用正交实验研究了单体配比,引发剂用量,溶剂用量,聚合温度对聚合物降冷滤效果的影响。共聚物用IR进行表征,利用XRD初步探讨了该降凝剂的降凝机理。结果表明:该剂能使吐哈—10~#、0~#柴油冷滤点降低10℃和7℃;使独山子0~#柴油冷滤点下降12℃;使石化0~#柴油冷滤点下降8℃;使克拉玛依0~#柴油的冷滤点下降8℃。  相似文献   
10.
1 Introduction Propylene as an important feedstock for organic chemicals is mainly originated from steam cracking and catalytic cracking processes. During the FCC process the propylene content varies with the FCC catalyst and process technology adopted, resulting in significant difference in propylene concentration in the cracked product——LPG. The conventional FCC pro- cess generally gives a propylene yield of around 4%, while the FCC process with maximization of propylene yield can in…  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-23

京公网安备 11010802026262号