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   3648篇
  免费   199篇
  国内免费   17篇
化学   2448篇
晶体学   24篇
力学   114篇
数学   409篇
物理学   869篇
  2023年   21篇
  2022年   39篇
  2021年   77篇
  2020年   85篇
  2019年   67篇
  2018年   56篇
  2017年   63篇
  2016年   133篇
  2015年   141篇
  2014年   146篇
  2013年   215篇
  2012年   260篇
  2011年   323篇
  2010年   186篇
  2009年   135篇
  2008年   255篇
  2007年   226篇
  2006年   188篇
  2005年   151篇
  2004年   127篇
  2003年   88篇
  2002年   90篇
  2001年   52篇
  2000年   76篇
  1999年   38篇
  1998年   48篇
  1997年   29篇
  1996年   36篇
  1995年   38篇
  1994年   38篇
  1993年   39篇
  1992年   35篇
  1991年   41篇
  1990年   34篇
  1989年   26篇
  1988年   27篇
  1987年   20篇
  1986年   22篇
  1985年   31篇
  1984年   28篇
  1983年   18篇
  1982年   18篇
  1981年   18篇
  1980年   11篇
  1979年   7篇
  1978年   7篇
  1977年   11篇
  1976年   7篇
  1975年   8篇
  1974年   8篇
排序方式: 共有3864条查询结果,搜索用时 15 毫秒
1.
Advances in Computational Mathematics - Persistence diagrams are one of the main tools in the field of Topological Data Analysis (TDA). They contain fruitful information about the shape of data....  相似文献   
2.
3.
4.
Numerical simulation methods regarding fabric and cloth draping are generally based on mechanical models. These models are usually applied to uniform grids representing the true geometry of the fabric. Fabrics being a very flexible material, wrinkles appear on its surface when submitted to free or constrained motion. The main problem of the simulation is to represent realistically cloth surface motion. This is strongly dependent on the surface discretization. We present a new cloth animation scheme based on adaptive surface discretization. It can be seen as a multi-grid method which allows us to obtain realistic simulations. We propose also a new mechanical model well suited to our adaptive meshing strategy. A numerical example is given to show the efficiency of the method. To cite this article: J. Villard et al., C. R. Acad. Sci. Paris, Ser. I 335 (2002) 561–566.  相似文献   
5.
Some structural and spectroscopic features of rare earth orthoaluminates are examined.The trigonal→ orthorhombic transition is studied in a series of NdxSm1−xAlO3 compounds. The evolution of the crystal structure is followed by X-ray analysis and optical absorption. The free ion and crystal field parameters of Nd3+ (4f3 configuration) are determined in LuAlO3:Nd3+.The anomaly of the calculated splitting of the levels is slight, but well characterized in NdAlO3. The spin correlated crystal field and orbitally correlated crystal field models are tested as well as an empirical correction which was proposed earlier.  相似文献   
6.
Investigation of the methanol extract of the roots of Gnidia involucrata (Thymelaeaceae) led to the isolation and characterization of two new 3,8″‐biflavonoid diastereoisomers, named GB‐4 ( 6a ) and GB‐4a ( 6b ). Their absolute configurations were determined in mixture by on‐line LC/CD measurements, which also allowed the revision of absolute configurations of the biflavanoids GB‐1 and GB‐2, and the configurational assignment of GB‐3.  相似文献   
7.
The dehydration of molybdic acid, MoO3---H2O, was studied by thermal analysis, X-ray diffractometry and FTIR spectroscopy. The results show that an intermediate phase, MoO3-2/3H2O is formed at 216 °C and the monoclinic form of MoO3 is grown above 350 °C. The mechanism of dehydration and structural rearrangement were confirmed by the features of the infrared spectra showing formation of corner-shared MoO6 octahedra.  相似文献   
8.
9.
The European Physical Journal C - We discuss possible searches for the new particles predicted by Little Higgs Models at the LHC. By using a simulation of the ATLAS detector, we demonstrate how the...  相似文献   
10.
The main transitions of cellulose fatty esters with different degrees of substitution (DSs) were investigated with dynamic mechanical thermal analysis. Two distinct main relaxations were observed in partially substituted cellulose esters (PSCEs). They were attributed to the glass‐transition temperature and to the chain local motion of the aliphatic substituents. The temperatures of both transitions decreased when DS or the number of carbon atoms (n) of the acyl substituent increased. Conversely, all the transitions of fully substituted cellulose esters occurred within a narrow temperature range, and they did not vary significantly with n. This phenomenon was explained by the formation of a crystalline phase of the fatty substituents. The presence of few residual OH groups in PSCEs was responsible for a large increase in the storage bending modulus, and it eliminated the effect of n on damping. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 281–288, 2003  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