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   168138篇
  免费   466篇
  国内免费   388篇
化学   54551篇
晶体学   2043篇
力学   12542篇
数学   52136篇
物理学   47720篇
  2021年   119篇
  2019年   83篇
  2018年   17743篇
  2017年   18434篇
  2016年   9175篇
  2015年   1706篇
  2014年   494篇
  2013年   557篇
  2012年   7585篇
  2011年   21405篇
  2010年   12079篇
  2009年   12544篇
  2008年   16533篇
  2007年   21947篇
  2006年   487篇
  2005年   8605篇
  2004年   5056篇
  2003年   5396篇
  2002年   2428篇
  2001年   409篇
  2000年   613篇
  1999年   192篇
  1998年   238篇
  1997年   164篇
  1996年   326篇
  1995年   206篇
  1994年   160篇
  1993年   162篇
  1992年   116篇
  1991年   130篇
  1990年   117篇
  1989年   136篇
  1988年   147篇
  1987年   141篇
  1986年   131篇
  1985年   144篇
  1984年   152篇
  1983年   140篇
  1982年   136篇
  1981年   142篇
  1980年   141篇
  1979年   150篇
  1978年   155篇
  1976年   82篇
  1975年   69篇
  1974年   59篇
  1973年   112篇
  1969年   86篇
  1968年   115篇
  1966年   64篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
1.
Journal of Thermal Analysis and Calorimetry - In the present framework, the simultaneous effect of rotation, magnetic field, heat source and local thermal non-equilibrium (LTNE) is investigated on...  相似文献   
2.
The European Physical Journal H - The widespread positivist approach of physics research in Italy at the turn of the XIX and XX centuries did not provide a fertile ground for the scientific debate...  相似文献   
3.
4.
5.
正Living organisms have developed their unique strategies during the natural evolution for building hard tissues with minerals, including silica, calcium carbonate, calcium phosphate, and ferric oxide [1]. Such biomineralized materials generally have complex hierarchical structures with excellent mechanical properties. Although bioinspired approaches have led to the creation of well-defined synthetic structural materials ranging from micro to macro scales, the rational design of discrete biomimetic structures at the nanoscale remains a grand challenge.  相似文献   
6.
Sufficient conditions for the compactness in generalized Morrey spaces of the composition of a convolution operator and the operator of multiplication by an essentially bounded function are obtained. Very weak conditions on the function are also obtained under which the commutator of the operator of multiplication by such a function and a convolution operator is compact. The compactness of convolution operators in domains of cone type is investigated.  相似文献   
7.
A five-neuron network model with multiple delays is proposed. This paper presents the combined effect of different delays on the dynamics of the proposed network. Pitchfork bifurcation is discussed in detail with the variation of the value of coupled weight or attenuation rate of internal neurons. By analyzing the corresponding characteristic equation, some stable criteria on delay-dependence and delay-independence are derived including multiple delays and coupled weights and the periodic oscillation arises bifurcated from the trivial equilibrium after the network loses its stability. Stable regions on delay-dependence are displayed in the two delayed parameter plane. It is shown that multiple delays can produce stability switching between resting state and periodic activity. Finally, theoretical results are justified by providing two illustrative examples.  相似文献   
8.
The curing of oligodienediol with a combined system consisting of a polyisocyanate and a (meth)acrylate-containing compound, which allows it to be structured with the polyisocyanate both at the terminal hydroxyl groups and double bonds due to the (meth)acrylate component, has been studied. The effect of the concentration of the (meth)acrylate component and a peroxide initiator to the degree of cross linking and strength properties of elastomers has been revealed. It has been shown that the participation of oligomer double bonds to form a vulcanization structure, creating the effect of “healing” defects from functional heterogeneity, allows one to increase the degree of cross linking and strength properties of polyurethanes.  相似文献   
9.
It is shown that the countably infinite dimensional pointed vector space (the vector space equipped with a constant) over a finite field has infinitely many first order definable reducts. This implies that the countable homogeneous Boolean-algebra has infinitely many reducts.  相似文献   
10.
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