全文获取类型
收费全文 | 5528篇 |
免费 | 309篇 |
国内免费 | 278篇 |
专业分类
化学 | 1005篇 |
晶体学 | 2篇 |
力学 | 269篇 |
综合类 | 19篇 |
数学 | 3853篇 |
物理学 | 967篇 |
出版年
2024年 | 10篇 |
2023年 | 64篇 |
2022年 | 102篇 |
2021年 | 101篇 |
2020年 | 137篇 |
2019年 | 157篇 |
2018年 | 118篇 |
2017年 | 148篇 |
2016年 | 130篇 |
2015年 | 128篇 |
2014年 | 243篇 |
2013年 | 626篇 |
2012年 | 297篇 |
2011年 | 364篇 |
2010年 | 289篇 |
2009年 | 425篇 |
2008年 | 371篇 |
2007年 | 365篇 |
2006年 | 269篇 |
2005年 | 197篇 |
2004年 | 205篇 |
2003年 | 195篇 |
2002年 | 134篇 |
2001年 | 113篇 |
2000年 | 111篇 |
1999年 | 120篇 |
1998年 | 98篇 |
1997年 | 97篇 |
1996年 | 90篇 |
1995年 | 75篇 |
1994年 | 62篇 |
1993年 | 38篇 |
1992年 | 33篇 |
1991年 | 30篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 27篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1973年 | 4篇 |
排序方式: 共有6115条查询结果,搜索用时 15 毫秒
1.
《Discrete Mathematics》2022,345(10):112984
Let G be a generalized dicyclic group with identity 1. An inverse closed subset S of is called minimal if and there exists some such that . In this paper, we characterize distance-regular Cayley graphs of G under the condition that S is minimal. 相似文献
2.
In this paper, we study generalized Douglas–Weyl(α, β)-metrics. Suppose that a regular(α, β)-metric F is not of Randers type. We prove that F is a generalized Douglas–Weyl metric with vanishing S-curvature if and only if it is a Berwald metric. Moreover, by ignoring the regularity, if F is not a Berwald metric, then we find a family of almost regular Finsler metrics which is not Douglas nor Weyl. As its application, we show that generalized Douglas–Weyl square metric or Matsumoto metric with isotropic mean Berwald curvature are Berwald metrics. 相似文献
3.
Mariusz Marć Marek Tobiszewski Bożena Zabiegała Miguel de la Guardia Jacek Namieśnik 《Analytica chimica acta》2015
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献
4.
Inner derivations and norm equality 总被引:3,自引:0,他引:3
Mohamed Barraa Mohamed Boumazgour 《Proceedings of the American Mathematical Society》2002,130(2):471-476
We characterize when the norm of the sum of two bounded operators on a Hilbert space is equal to the sum of their norms.
5.
矩阵方程A^TXB=C的正定和半正定解 总被引:5,自引:1,他引:4
何楚宁 《高校应用数学学报(A辑)》1997,(4):475-480
给出了矩阵方程A^TXB=C在正定和半正定矩阵类中有解的充要条件及解的一般表达式。 相似文献
6.
The theory of tree-growing (RECPAM approach) is developed for outcome variables which are distributed as the canonical exponential family. The general RECPAM approach (consisting of three steps: recursive partition, pruning and amalgamation), is reviewed. This is seen as constructing a partition with maximal information content about a parameter to be predicted, followed by simplification by the elimination of ‘negligible’ information. The measure of information is defined for an exponential family outcome as a deviance difference, and appropriate modifications of pruning and amalgamation rules are discussed. It is further shown how the proposed approach makes it possible to develop tree-growing for situations usually treated by generalized linear models (GLIM). In particular, Poisson and logistic regression can be tree-structured. Moreover, censored survival data can be treated, as in GLIM, by observing a formal equivalence of the likelihood under random censoring and an appropriate Poisson model. Three examples are given of application to Poisson, binary and censored survival data. 相似文献
7.
G. Dattoli 《Journal of Mathematical Analysis and Applications》2002,269(2):716-725
Bilateral generating functions are those involving products of different types of polynomials. We show that operational methods offer a powerful tool to derive these families of generating functions. We study cases relevant to products of Hermite polynomials with Laguerre, Legendre and other polynomials. We also propose further extensions of the method which we develop here. 相似文献
8.
本文在一类 Lp位势V(x)下建立了广义Schrodinger算子H=(-Δ)m+V(x)在C∞0(Rn)上的本质自伴性,给出了H的本质谱的分布. 相似文献
9.
可变抽样区间的非参数控制图 总被引:1,自引:1,他引:0
最近几年一些学者研究了可变抽样区间的质量控制图。Amin等提出了可变抽样区间(VSI)的非参数控制图———符号 (Sign)统计量图〔1〕。本文在此基础上研究位置VSI符号控制图的制定方法 ,并设计离散VSI符号控制图。符号控制图的优点是对非正态总体亦可应用 ,并且不需要过程方差的信息。本文将所设计的VSI符号控制图同固定抽样区间 (FSI)的常规图作比较 ,并举实例说明符号控制图的应用 相似文献
10.
设珮犠(狋):犚犖+ →犚犱是犖指标犱维广义Wiener过程,对任意紧集犈1,…,犈犿犚犖> ,该文研究了犿项代数和珮犠(犈1)…珮犠(犈犿)的Hausdorff维数,Packing维数和正的Lebesgue测度及内点的存在性. 其结果包含并推广了布朗单的结果. 相似文献