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   667936篇
  免费   7514篇
  国内免费   1985篇
化学   343321篇
晶体学   9363篇
力学   31091篇
综合类   14篇
数学   91034篇
物理学   202612篇
  2021年   4724篇
  2020年   5317篇
  2019年   5850篇
  2018年   13235篇
  2017年   13639篇
  2016年   13998篇
  2015年   7884篇
  2014年   11169篇
  2013年   28033篇
  2012年   23895篇
  2011年   34277篇
  2010年   22788篇
  2009年   22595篇
  2008年   30762篇
  2007年   33058篇
  2006年   21833篇
  2005年   24419篇
  2004年   20467篇
  2003年   18406篇
  2002年   16805篇
  2001年   17805篇
  2000年   13655篇
  1999年   10702篇
  1998年   8933篇
  1997年   8679篇
  1996年   8472篇
  1995年   7675篇
  1994年   7482篇
  1993年   7351篇
  1992年   8126篇
  1991年   8232篇
  1990年   7862篇
  1989年   7697篇
  1988年   7780篇
  1987年   7575篇
  1986年   7183篇
  1985年   9496篇
  1984年   9775篇
  1983年   7922篇
  1982年   8288篇
  1981年   8017篇
  1980年   7538篇
  1979年   8019篇
  1978年   8351篇
  1977年   8083篇
  1976年   8233篇
  1975年   7489篇
  1974年   7560篇
  1973年   7851篇
  1972年   5306篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
121.
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237  相似文献   
122.
Journal of Solid State Electrochemistry - The “shuttle effect” of polysulfides is a serious issue, resulting in a decrease in the life-cycle of lithium-sulfur (Li-S) batteries. To...  相似文献   
123.
Journal of Thermal Analysis and Calorimetry - The role of method of synthesis on the size of flakes, dispersion stability and thermophysical properties of aqua based reduced graphene oxide (rGO)...  相似文献   
124.
Russian Journal of Organic Chemistry - A green protocol has been developed for the preparation of 2,2′-(arylmethylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones) following the...  相似文献   
125.
126.
127.
128.
Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters.  相似文献   
129.
130.
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