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   91378篇
  免费   951篇
  国内免费   415篇
化学   33472篇
晶体学   1007篇
力学   7121篇
综合类   1篇
数学   32919篇
物理学   18224篇
  2023年   166篇
  2022年   327篇
  2021年   426篇
  2020年   471篇
  2019年   528篇
  2018年   10752篇
  2017年   10560篇
  2016年   6672篇
  2015年   1301篇
  2014年   1038篇
  2013年   1557篇
  2012年   4806篇
  2011年   11497篇
  2010年   6314篇
  2009年   6583篇
  2008年   7240篇
  2007年   9379篇
  2006年   760篇
  2005年   1777篇
  2004年   1879篇
  2003年   2252篇
  2002年   1250篇
  2001年   395篇
  2000年   417篇
  1999年   248篇
  1998年   259篇
  1997年   242篇
  1996年   289篇
  1995年   187篇
  1994年   145篇
  1993年   184篇
  1992年   149篇
  1991年   140篇
  1990年   116篇
  1989年   130篇
  1988年   107篇
  1987年   104篇
  1986年   100篇
  1985年   112篇
  1984年   106篇
  1983年   91篇
  1982年   88篇
  1981年   76篇
  1980年   91篇
  1979年   105篇
  1978年   82篇
  1977年   70篇
  1976年   57篇
  1975年   50篇
  1973年   49篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Molecular Diversity - The antifungals that are in current clinical practice have a high occurrence of a side effect and multidrug resistance (MDR). Researchers across the globe are trying to...  相似文献   
22.
23.
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.  相似文献   
24.
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting.  相似文献   
25.
26.
27.
28.
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form.  相似文献   
29.
30.
Plant derived flavonoids have not been well explored in tissue engineering applications due to difficulties in efficient formulations with biomaterials for controlled presentation. Here, the authors report that surface coating of epigallocatechin gallate (EGCG) on polymeric substrates including poly (L‐lactic acid) (PLLA) nanofibers can be performed via oxidative polymerization of EGCG in the presence of cations, enabling regulation of biological functions of multiple cell types implicated in bone regeneration. EGCG coating on the PLLA nanofiber promotes osteogenic differentiation of adipose‐derived stem cells (ADSCs) and is potent to suppress adipogenesis of ADSCs while significantly reduces osteoclastic maturation of murine macrophages. Moreover, EGCG coating serves as a protective layer for ADSCs against oxidative stress caused by hydrogen peroxide. Finally, the in vivo implantation of EGCG‐coated nanofibers into a mouse calvarial defect model significantly promotes the bone regeneration (61.52 ± 28.10%) as compared to defect (17.48 ± 11.07%). Collectively, the results suggest that EGCG coating is a simple bioinspired surface modification of polymeric biomaterials and importantly can thus serve as a promising interface for tuning activities of multiple cell types associated with bone fracture healing.  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