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   273183篇
  免费   2336篇
  国内免费   733篇
化学   127235篇
晶体学   3991篇
力学   14544篇
综合类   7篇
数学   42184篇
物理学   88291篇
  2021年   991篇
  2020年   1114篇
  2019年   1129篇
  2018年   10441篇
  2017年   11409篇
  2016年   6538篇
  2015年   2847篇
  2014年   2616篇
  2013年   7824篇
  2012年   10751篇
  2011年   20848篇
  2010年   12440篇
  2009年   12591篇
  2008年   18267篇
  2007年   21899篇
  2006年   7211篇
  2005年   13887篇
  2004年   9568篇
  2003年   8565篇
  2002年   6399篇
  2001年   6192篇
  2000年   4868篇
  1999年   3518篇
  1998年   2672篇
  1997年   2634篇
  1996年   2746篇
  1995年   2375篇
  1994年   2248篇
  1993年   2101篇
  1992年   2406篇
  1991年   2379篇
  1990年   2093篇
  1989年   2078篇
  1988年   2108篇
  1987年   2041篇
  1986年   1945篇
  1985年   2860篇
  1984年   2857篇
  1983年   2296篇
  1982年   2474篇
  1981年   2361篇
  1980年   2315篇
  1979年   2278篇
  1978年   2357篇
  1977年   2228篇
  1976年   2194篇
  1975年   2177篇
  1974年   2071篇
  1973年   2197篇
  1972年   1233篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
π-Extended molecules are key components for the development of materials science. In fact, polyaromatic structures are fundamental for the scientific and technological progress of fields such as organic electronics and bio-applications. Beneficial properties of π-extended structures are absorption in the visible region, often luminescence, high electron mobilities and stability. Common approaches to adjust the properties of polyaromatic structures to functional setups involve changes in shape and size at the molecular level. Recently, incorporating hetero-elements emerged as successful approach. In this regard, organophosphorus conjugated molecules are new materials holding great promise for potential applications. In this review, we comprehensively discuss the design/development of polyaromatic phosphorus materials and their applicability. We establish structure/property/applicability relationships to provide key guidelines for the engineering of newer, future applications. This article thus provides a source of information for the further development of this rapidly evolving field of research.  相似文献   
72.
73.
74.
75.
Li  C.  Zhang  D.  Cheng  G.  Zhu  Y. 《Experimental Mechanics》2020,60(3):329-343
Experimental Mechanics - There have been relatively few studies on mechanical properties of nanomaterials under high strain rates, mainly due to the lack of capable nanomechanical testing devices....  相似文献   
76.
The first immobilized catalyst for Ir‐catalyzed asymmetric allylic aminations is described. The catalyst is a cationic (π‐allyl)Ir complex bound by cation exchange to an anionic silica gel support. Preparation of the catalyst is facile, and the supported catalyst displayed considerably enhanced activity compared with the parent homogeneous catalyst. Up to 43 consecutive amination runs were possible in recycling experiments.  相似文献   
77.
78.
Submicron CaZrO3 powder is obtained in combustion reactions (solution combustion synthesis—SCS) with glycine. It is found that SCS reduces the sintering temperature of CaZrO3 powders. The dielectric properties of calcium zirconate ceramics are studied by the electrochemical impedance method. It is shown that a ceramics of powders obtained by the SCS method has high dielectric characteristics.  相似文献   
79.
80.
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius r=50 nm and different distance d between the disks centers (from d=12 nm to d=2R=100 nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices.  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