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   212301篇
  免费   2684篇
  国内免费   1530篇
化学   111364篇
晶体学   3476篇
力学   10689篇
综合类   112篇
数学   22844篇
物理学   68030篇
  2021年   2320篇
  2020年   2398篇
  2019年   2945篇
  2018年   3972篇
  2017年   3980篇
  2016年   5254篇
  2015年   2778篇
  2014年   4845篇
  2013年   9228篇
  2012年   7660篇
  2011年   8826篇
  2010年   6978篇
  2009年   7122篇
  2008年   8236篇
  2007年   8182篇
  2006年   7163篇
  2005年   6346篇
  2004年   5931篇
  2003年   5403篇
  2002年   5390篇
  2001年   5820篇
  2000年   4352篇
  1999年   3315篇
  1998年   2870篇
  1997年   2899篇
  1996年   2700篇
  1995年   2355篇
  1994年   2435篇
  1993年   2326篇
  1992年   2604篇
  1991年   2710篇
  1990年   2616篇
  1989年   2662篇
  1988年   2569篇
  1987年   2584篇
  1986年   2436篇
  1985年   3069篇
  1984年   3114篇
  1983年   2610篇
  1982年   2578篇
  1981年   2533篇
  1980年   2341篇
  1979年   2716篇
  1978年   2674篇
  1977年   2878篇
  1976年   2881篇
  1975年   2666篇
  1974年   2605篇
  1973年   2715篇
  1972年   2089篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
In the article, it is proved that any nonnegative solution of an elliptic quasilinear inequality that vanishes on a subset of positive measure is trivial. __________ Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 25, pp. 112–118, 2005.  相似文献   
43.
44.
This article deals with an expanded mixed finite element formulation, based on the Hu‐Washizu principle, for a nonlinear incompressible material in the plane. We follow our related previous works and introduce both the stress and the strain tensors as further unknowns, which yields a two‐fold saddle point operator equation as the corresponding variational formulation. A slight generalization of the classical Babu?ka‐Brezzi's theory is applied to prove unique solvability of the continuous and discrete formulations, and to derive the corresponding a priori error analysis. An extension of the well‐known PEERS space is used to define an stable associated Galerkin scheme. Finally, we provide an a posteriori error analysis based on the classical Bank‐Weiser approach. © 2002 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 18: 105–128, 2002  相似文献   
45.
46.
Specific features of the initiated oxidation of polyethylene and its low-molecular-weight analogue tridecane, associated with the occurrence of the process in the short-chain mode, were studied.  相似文献   
47.
The luminescence and scintillation properties of poly(methyl methacrylate) containing 1,1,3-trimethyl-3-phenylindan were studied.  相似文献   
48.
The structural change in the depth direction of a polyimide (UPILEX‐S) film treated in alkaline solution, which was a representative surface treatment used to form a seed layer for plating and to improve the adhesive strength, was analyzed by means of micro Fourier transform infrared attenuated total reflection (FTIR‐ATR) line analysis with gradient shaving preparation. The polyimide film was treated with KOH. The imide ring opened through the alkaline treatment, and the amide structure and carboxylic acid salt were formed. The attainment depth of this structural change was almost proportional to the treatment time, and it reached about 8 μm after a 30‐min treatment. The degree of structural change through the alkaline treatment was almost constant after it reached a considerably degraded stage, and the chemically changed region penetrated into the inner part of the film from the surface. An intermediate layer before the final degraded stage appeared in the treated layer, and its thickness increased with the treatment time. The region that was changed chemically by the alkaline treatment progressed to the inner part simultaneously and continuously as the treatment time increased. The combined use of gradient shaving preparation and micro FTIR‐ATR line analysis was found to be extremely effective for the depth profiling of organic materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2071–2078, 2003  相似文献   
49.
50.
The generalized Hilbert symbol in a cyclotomic extension of an absolutely unramified higher local field of characteristic 0 with a perfect last residue field of characteristic p > 2 is considered. Generalized Artin–Hasse and Iwasawa formulas are derived from an explicit Kummer Type Vostokov formula. Bibliography: 13 titles.  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