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   220860篇
  免费   2953篇
  国内免费   1324篇
化学   122849篇
晶体学   3230篇
力学   8892篇
综合类   61篇
数学   24387篇
物理学   65718篇
  2020年   1754篇
  2019年   1900篇
  2018年   2485篇
  2017年   2532篇
  2016年   3647篇
  2015年   2424篇
  2014年   3538篇
  2013年   8886篇
  2012年   7694篇
  2011年   9403篇
  2010年   6654篇
  2009年   6454篇
  2008年   8802篇
  2007年   8913篇
  2006年   8390篇
  2005年   7710篇
  2004年   6879篇
  2003年   6066篇
  2002年   5988篇
  2001年   6706篇
  2000年   5070篇
  1999年   3671篇
  1998年   3040篇
  1997年   3012篇
  1996年   3017篇
  1995年   2619篇
  1994年   2718篇
  1993年   2581篇
  1992年   2832篇
  1991年   2897篇
  1990年   2707篇
  1989年   2617篇
  1988年   2560篇
  1987年   2500篇
  1986年   2521篇
  1985年   3307篇
  1984年   3366篇
  1983年   2807篇
  1982年   3050篇
  1981年   2813篇
  1980年   2609篇
  1979年   2791篇
  1978年   3003篇
  1977年   3033篇
  1976年   3060篇
  1975年   2793篇
  1974年   2911篇
  1973年   2958篇
  1972年   2318篇
  1971年   1845篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs).  相似文献   
23.
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   
24.
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   
25.
26.
27.
28.
29.
Journal of Structural Chemistry - An analysis is presented for the results obtained in the studies initiated by A. E. Shvelashivili, Corresponding Member, Academy of Sciences of Georgia, and...  相似文献   
30.
Thin films (monolayer and bilayer) of cylinder forming polystyrene‐block‐polydimethylsiloxane (PS‐b‐PDMS) were shear aligned by the swelling and deswelling of a crosslinked PDMS pad that was physically adhered to the film during solvent vapor annealing. The nanostructures formed by self‐assembly were exposed to ultraviolet‐ozone to partially oxidize the PDMS, followed by calcination in air at 500 °C. In this process, the PS segments were fully decomposed, while the PDMS yielded silica nanostructures. The highly aligned PDMS cylinders were thus deposited as silica nanolines on the silicon substrate. Using a bilayer film, the center‐to‐center distance of these features were effectively halved from 38 to 19 nm. Similarly, by sequential shear‐alignment of two distinct layers, a rhombic array of silica nanolines was fabricated. This methodology provides a facile route to fabricating complex topographically patterned nanostructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1058–1064  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