全文获取类型
收费全文 | 4437篇 |
免费 | 456篇 |
国内免费 | 291篇 |
专业分类
化学 | 219篇 |
晶体学 | 1篇 |
力学 | 97篇 |
综合类 | 97篇 |
数学 | 2827篇 |
物理学 | 395篇 |
无线电 | 1548篇 |
出版年
2024年 | 5篇 |
2023年 | 41篇 |
2022年 | 86篇 |
2021年 | 103篇 |
2020年 | 134篇 |
2019年 | 150篇 |
2018年 | 115篇 |
2017年 | 153篇 |
2016年 | 170篇 |
2015年 | 147篇 |
2014年 | 271篇 |
2013年 | 324篇 |
2012年 | 271篇 |
2011年 | 278篇 |
2010年 | 244篇 |
2009年 | 277篇 |
2008年 | 348篇 |
2007年 | 297篇 |
2006年 | 275篇 |
2005年 | 216篇 |
2004年 | 195篇 |
2003年 | 187篇 |
2002年 | 151篇 |
2001年 | 119篇 |
2000年 | 106篇 |
1999年 | 84篇 |
1998年 | 85篇 |
1997年 | 63篇 |
1996年 | 59篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1936年 | 1篇 |
排序方式: 共有5184条查询结果,搜索用时 718 毫秒
1.
2.
We generalize Nagel’s formula for the Szegö kernel and use it to compute the Szegö kernel on a class of non-compact CR manifolds whose tangent space decomposes into one complex direction and several totally real directions. We also discuss the control metric on these manifolds and relate it to the size of the Szegö kernel. 相似文献
3.
Ratnabali Biswas Kaushik Chowdhury Dharma P. Agrawal 《International Journal of Wireless Information Networks》2006,13(4):303-315
Wireless sensor network is an emerging technology that enables remote monitoring of large geographical regions. In this paper, we address the problem of distributing attributes over such a large-scale sensor network so that the cost of data retrieval is minimized. The proposed scheme is a data-centric storage scheme where the attributes are distributed over the network depending on the correlations between them. The problem addressed here is similar to the Allocation Problem of distributed databases. In this paper, we have defined the Allocation Problem in the context of sensor networks and have proposed a scheme for finding a good distribution of attributes to the sensor network. We also propose an architecture for query processing given such a distribution of attributes. We analytically determine the conditions under which the proposed architecture is beneficial and present simulation results to demonstrate the same. To the best of our knowledge, this is the first attempt to determine an allocation of attributes over a sensor network based on the correlations between attributes. 相似文献
4.
探讨分类挖掘技术在高校实际工作中的应用方式与应用领域。以高校人事管理为模型,应用数据挖掘中决策树算法,对高校人力资源数据源中的信息进行分析,发现其中有价值的数据模式,寻找其中存在的关系和规则,对高校人才规划提供比较客观的决策支持。 相似文献
5.
6.
首先建立了数据传输网络选择的最小成本模型,给出了有效支撑树代表集的概念,并给出了一个时间复杂性为D(mlogen)的算法产生代表集。然后对静态数据传输问题和在线数据传输问题,分别给出了一个时间复杂性为D(mlogen)和O(m^2 mlogen)的多项式时间的算法。 相似文献
7.
8.
Boundedness of commutators on homogeneous Herz spaces 总被引:9,自引:0,他引:9
The boundedness on homogeneous Herz spaces is established for a large class of linear commutators generated by BMO(R
n
) functions and linear operators of rough kernels which include the Calderón-Zygmund operators and the Ricci-Stein oRfiUatory
singular integrals with rough kernels.
Project supponed in pan by the National h’atural Science Foundation of China (Grant No. 19131080) and the NEDF of China. 相似文献
9.
Nobuaki Obata 《Acta Appl Math》1997,47(1):49-77
A general theory of operators on Boson Fock space is discussed in terms of the white noise distribution theory on Gaussian space (white noise calculus). An integral kernel operator is generalized from two aspects: (i) The use of an operator-valued distribution as an integral kernel leads us to the Fubini type theorem which allows an iterated integration in an integral kernel operator. As an application a white noise approach to quantum stochastic integrals is discussed and a quantum Hitsuda–Skorokhod integral is introduced. (ii) The use of pointwise derivatives of annihilation and creation operators assures the partial integration in an integral kernel operator. In particular, the particle flux density becomes a distribution with values in continuous operators on white noise functions and yields a representation of a Lie algebra of vector fields by means of such operators. 相似文献
10.
A Necessary and Sufficient Condition for the Existence of a Heterochromatic Spanning Tree in a Graph
Kazuhiro Suzuki 《Graphs and Combinatorics》2006,22(2):261-269
We prove the following theorem. An edge-colored (not necessary to be proper) connected graph G of order n has a heterochromatic spanning tree if and only if for any r colors (1≤r≤n−2), the removal of all the edges colored with these r colors from G results in a graph having at most r+1 components, where a heterochromatic spanning tree is a spanning tree whose edges have distinct colors. 相似文献