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   294859篇
  免费   2783篇
  国内免费   557篇
化学   138855篇
晶体学   4072篇
力学   14527篇
综合类   5篇
数学   48262篇
物理学   92478篇
  2021年   1628篇
  2020年   1835篇
  2019年   2018篇
  2018年   11152篇
  2017年   11996篇
  2016年   8147篇
  2015年   3551篇
  2014年   4104篇
  2013年   9567篇
  2012年   11667篇
  2011年   20702篇
  2010年   13113篇
  2009年   13061篇
  2008年   18353篇
  2007年   21730篇
  2006年   7637篇
  2005年   13296篇
  2004年   9533篇
  2003年   8774篇
  2002年   6592篇
  2001年   5941篇
  2000年   4681篇
  1999年   3391篇
  1998年   2806篇
  1997年   2669篇
  1996年   2767篇
  1995年   2470篇
  1994年   2471篇
  1993年   2337篇
  1992年   2608篇
  1991年   2543篇
  1990年   2487篇
  1989年   2387篇
  1988年   2318篇
  1987年   2300篇
  1986年   2207篇
  1985年   2912篇
  1984年   2968篇
  1983年   2570篇
  1982年   2696篇
  1981年   2519篇
  1980年   2515篇
  1979年   2628篇
  1978年   2682篇
  1977年   2522篇
  1976年   2615篇
  1975年   2505篇
  1974年   2443篇
  1973年   2666篇
  1972年   1694篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Set-Valued and Variational Analysis - In a Hilbert framework ℌ, we study the convergence properties of a Newton-like inertial dynamical system governed by a general maximally monotone...  相似文献   
12.
Van’kov  A. B.  Kukushkin  I. V. 《JETP Letters》2021,113(2):102-114
JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been...  相似文献   
13.
Algebra and Logic - Unary functions definable in o-stable ordered groups of nonvaluational type are studied. Such functions are proved to be piecewise monotone and continuous.  相似文献   
14.
Ferrarini  A.  Finotello  A.  Salsano  G.  Auricchio  F.  Palombo  D.  Spinella  G.  Pane  B.  Conti  M. 《Acta Mechanica Sinica》2021,37(7):1192-1192
Acta Mechanica Sinica - A Correction to this paper has been published: https://doi.org/10.1007/s10409-021-01066-2  相似文献   
15.
16.
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.  相似文献   
17.
Journal of Mathematical Chemistry - The analytical solutions of an asymmetric double well potential $$V(x)=a\, x^2-b\, x^3+c\, x^4$$ are found to be a triconfluent Heun function $$H_{T}(\alpha ,...  相似文献   
18.
Journal of Applied and Industrial Mathematics - We study the problem of optimal location of the ambulance fleet at the base stations. The objective is to minimize the average waiting time for...  相似文献   
19.
A liquid dewetting method for the determination of the viscoelastic properties of ultrathin polymer films has been extended to study thickness effects on the properties of ultrathin polycarbonate (PC) films. PC films with film thicknesses ranging from 4 to 299 nm were placed on glycerol at temperatures from below the macroscopic glass transition temperature (Tg) to above it with the dewetting responses being monitored. It is found that the isothermal creep results for films of the same thickness, but dewetted at different temperatures can be superposed into one master curve, which is consistent with the fact of PC being a thermorheologically simple material. Furthermore, the results show that the Tg of PC thin films is thickness dependent, but the dependence is weaker than the results for freely standing films and similar to literature data for PC films supported on rigid substrates. It was also found that the rubbery plateau region for the PC films stiffens dramatically, but still less than what has been observed for freely standing polycarbonate films. The rubbery stiffening is discussed in terms of a recently reported model that relates macroscopic segmental dynamics with the stiffening. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1559–1566  相似文献   
20.
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