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   9650篇
  免费   1358篇
  国内免费   3380篇
化学   6319篇
晶体学   388篇
力学   510篇
综合类   141篇
数学   4091篇
物理学   2939篇
  2024年   29篇
  2023年   90篇
  2022年   245篇
  2021年   291篇
  2020年   328篇
  2019年   316篇
  2018年   323篇
  2017年   463篇
  2016年   594篇
  2015年   395篇
  2014年   615篇
  2013年   1111篇
  2012年   873篇
  2011年   858篇
  2010年   730篇
  2009年   769篇
  2008年   794篇
  2007年   758篇
  2006年   629篇
  2005年   565篇
  2004年   448篇
  2003年   415篇
  2002年   405篇
  2001年   354篇
  2000年   291篇
  1999年   269篇
  1998年   233篇
  1997年   202篇
  1996年   181篇
  1995年   151篇
  1994年   133篇
  1993年   89篇
  1992年   79篇
  1991年   51篇
  1990年   58篇
  1989年   29篇
  1988年   39篇
  1987年   24篇
  1986年   14篇
  1985年   17篇
  1984年   15篇
  1983年   18篇
  1982年   22篇
  1981年   8篇
  1980年   16篇
  1979年   10篇
  1978年   9篇
  1977年   7篇
  1976年   8篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
We study the existence of a time‐periodic solution with pointwise decay properties to the Navier–Stokes equation in the whole space. We show that if the time‐periodic external force is sufficiently small in an appropriate sense, then there exists a time‐periodic solution { u , p } of the Navier–Stokes equation such that | ? j u ( t , x ) | = O ( | x | 1 ? n ? j ) and | ? j p ( t , x ) | = O ( | x | ? n ? j ) ( j = 0 , 1 , ) uniformly in t R as | x | . Our solution decays faster than the time‐periodic Stokes fundamental solution and the faster decay of its spatial derivatives of higher order is also described.  相似文献   
2.
3.
4.
We solve a combinatorial question concerning eigenvalues of the universal intertwining endomorphism of a subset representation.  相似文献   
5.
6.
7.
The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP.  相似文献   
8.
We define the notion of basic set data for finite groups (building on the notion of basic set, but including an order on the irreducible characters as part of the structure), and we prove that the Springer correspondence provides basic set data for Weyl groups. Then we use this to determine explicitly the modular Springer correspondence for classical types (defined over a base field of odd characteristic p, and with coefficients in a field of odd characteristic ?p): the modular case is obtained as a restriction of the ordinary case to a basic set. In order to do so, we compare the order on bipartitions introduced by Dipper and James with the order induced by the Springer correspondence. We provide a quick proof, by sorting characters according to the dimension of the corresponding Springer fibre, an invariant which is directly computable from symbols.  相似文献   
9.
A graph is concave-round if its vertices can be circularly enumerated so that the closed neighborhood of each vertex is an interval in the enumeration. In this study, we give a minimal forbidden induced subgraph characterization for the class of concave-round graphs, solving a problem posed by Bang-Jensen, Huang, and Yeo [SIAM J. Discrete Math., 13 (2000), pp. 179–193]. In addition, we show that it is possible to find one such forbidden induced subgraph in linear time in any given graph that is not concave-round. As part of the analysis, we obtain characterizations by minimal forbidden submatrices for the circular-ones property for rows and for the circular-ones property for rows and columns and show that, also for both variants of the property, one of the corresponding forbidden submatrices can be found (if present) in any given matrix in linear time. We make some final remarks regarding connections to some classes of circular-arc graphs.  相似文献   
10.
Surimi from silver carp with different salt contents (0–5%) was obtained treated by high intensity ultrasound (HIU, 100 kHz 91 W·cm−2). The gelation properties of samples were evaluated by puncture properties, microstructures, water-holding capacity, dynamic rheological properties and intermolecular interactions. As the salt content increased from 0 to 5%, gel properties of surimi without HIU significantly improved. For samples with low-salt (0–2% NaCl) content, HIU induced obvious enhancement in breaking force and deformation. HIU promoted the protein aggregation linked by SS bonds, hydrophobic interactions and non-disulfide covalent bonds in surimi gels with low-salt content. Moreover, microstructures of HIU surimi gels with low-salt content were more compact than those of the corresponding control samples. HIU also improved the gelation properties of surimi with 3% NaCl to an extent. However, for high-salt (4–5% NaCl) samples, HIU decreased the breaking force and deformation of surimi gels due to the degradation of proteins suggested by increased TCA-soluble peptides. In conclusion, HIU effectively improved the gelation properties of surimi with low-salt content (0–2% NaCl), but was harmful for high-salt (4–5% NaCl) surimi. This might provide the theoretical basis for the production of low-salt surimi gels.  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