全文获取类型
收费全文 | 783篇 |
免费 | 30篇 |
国内免费 | 72篇 |
专业分类
化学 | 160篇 |
晶体学 | 3篇 |
力学 | 41篇 |
综合类 | 32篇 |
数学 | 559篇 |
物理学 | 90篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 27篇 |
2021年 | 22篇 |
2020年 | 18篇 |
2019年 | 15篇 |
2018年 | 23篇 |
2017年 | 19篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 30篇 |
2013年 | 61篇 |
2012年 | 35篇 |
2011年 | 38篇 |
2010年 | 37篇 |
2009年 | 46篇 |
2008年 | 58篇 |
2007年 | 55篇 |
2006年 | 32篇 |
2005年 | 38篇 |
2004年 | 45篇 |
2003年 | 37篇 |
2002年 | 32篇 |
2001年 | 28篇 |
2000年 | 24篇 |
1999年 | 24篇 |
1998年 | 19篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有885条查询结果,搜索用时 234 毫秒
91.
We introduce root systems for those imprimitive complex reflection groups which are generated by involutory reflections, and study the associated length functions. These have many properties in common with the usual length functions for finite Weyl groups. 相似文献
92.
设奇数q≥3存在原根,本文研究模q的原根中D.H.Lehmer数的分布性质,并给出一个较强的渐近公式。 相似文献
93.
在有向网络中寻找最小支撑入树的计算方法 总被引:1,自引:0,他引:1
翟晓燕 《数学的实践与认识》2002,32(6):973-978
本文研究了有向网络中支撑入树的性质 ,提出了在有向网络图中寻找以某一指定点为根的最小支撑入树的一种较简便的算法 ,并给出了应用该算法的一个实际算例 相似文献
94.
匹配最大根小于等于2的图的匹配等价 总被引:2,自引:0,他引:2
给出了十六个匹配等价桥,证明了两个匹配最大根小于等于2的图匹配等价当且仅当它们之间可以由这十六个匹配等价桥进行等价转换,完整地刻画了这些图的补图的匹配等价图类,找到了这些图和它们的补图中的所有匹配唯一图. 相似文献
95.
B(H)表示定义在希尔伯特空间H上的所有有界线性算子的全体。对于A∈B(H),其中σ(A)和W(A)分别表示算子A的谱和数值域,N表示自然数集。关于算子A的n(n∈N)次方根,本文的主要结果是:(1)若σ(A)∩(-∞,0]=φ,则A有惟一的n次方根B∈B(H)且σ(B)(?)~(2/n)~o;(2)若(?)∩(-∞,0]=φ,则A有惟一的n次方根B∈B(H)且(?)(2/n)~o这里,S_(1/n)={λ∈C‖argλ|≤(1/2n)π}且S_(1/n)~o表示集合S+(1/n)的内部。 相似文献
96.
In this paper we explore the usefulness of induced-order statistics in the characterization of integrated series and of cointegration
relationships. We propose a non-parametric test statistic for testing the null hypothesis of two independent random walks
against wide cointegrating alternatives including monotonic nonlinearities and certain types of level shifts in the cointegration
relationship. We call our testing device the induced-order Kolmogorov–Smirnov cointegration test (KS), since it is constructed
from the induced-order statistics of the series, and we derive its limiting distribution. This non-parametric statistic endows
the test with a number of desirable properties: invariance to monotonic transformations of the series, and robustness for
the presence of important parameter shifts. By Monte Carlo simulations we analyze the small sample properties of this test.
Our simulation results show the robustness of the induced order cointegration test against departures from linear and constant
parameter models.
This paper is an extension of the work of Aparicio and Granger (1995) and Aparicio and Escribano (1998). 相似文献
97.
Bin Zhu 《Journal of Algebraic Combinatorics》2008,27(1):35-54
We give a quiver representation theoretic interpretation of generalized cluster complexes defined by Fomin and Reading. Using
d-cluster categories defined by Keller as triangulated orbit categories of (bounded) derived categories of representations
of valued quivers, we define a d-compatibility degree (−∥−) on any pair of “colored” almost positive real Schur roots which generalizes previous definitions on the noncolored case
and call two such roots compatible, provided that their d-compatibility degree is zero. Associated to the root system Φ corresponding to the valued quiver, using this compatibility relation, we define a simplicial complex which has colored almost
positive real Schur roots as vertices and d-compatible subsets as simplices. If the valued quiver is an alternating quiver of a Dynkin diagram, then this complex is
the generalized cluster complex defined by Fomin and Reading.
Supported by the NSF of China (Grants 10471071) and by the Leverhulme Trust through the network ‘Algebras, Representations
and Applications’. 相似文献
98.
The chromatic polynomial PG(q) of a loopless graph G is known to be non-zero (with explicitly known sign) on the intervals (−∞,0), (0,1) and (1,32/27]. Analogous theorems hold for the flow polynomial of bridgeless graphs and for the characteristic polynomial of loopless matroids. Here we exhibit all these results as special cases of more general theorems on real zero-free regions of the multivariate Tutte polynomial ZG(q,v). The proofs are quite simple, and employ deletion–contraction together with parallel and series reduction. In particular, they shed light on the origin of the curious number 32/27. 相似文献
99.
Peter Somora 《Mathematica Slovaca》2008,58(4):439-454
A second order nonlinear differential equation with homogeneous Dirichlet boundary conditions is considered. An explicit expression
for the root functions for an autonomous nonlinear boundary value problem is obtained using the results of the paper [SOMORA,
P.: The lower bound of the number of solutions for the second order nonlinear boundary value problem via the root functions method, Math. Slovaca 57 (2007), 141–156]. Other assumptions are supposed to prove the monotonicity of root functions and to get the exact number
of solutions. The existence of infinitely many solutions of the boundary value problem with strong nonlinearity is obtained
by the root function method as well.
The paper was supported by the Grant VEGA No. 2/7140/27, Bratislava. 相似文献
100.
Eduardo Vyhmeister Anthony J. Muscat David Suleiman L. Antonio Estvez 《Fluid Phase Equilibria》2008,270(1-2):121-128
Fluid-phase equilibria, including dew points, bubble points, and critical points were measured for four binary systems composed of a chlorosilane and carbon dioxide. The measurements were carried out in a constant-composition, variable-volume cell equipped with a sapphire window, which allowed visual observation of the phases in the cell. A syringe pump was used to inject the CO2 into the cell and to control its pressure. Methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and diethyldichlorosilane up to about 0.14 mol fraction were studied in this apparatus and a total of 243 phase-boundary points were obtained. Displacements in the critical point with respect to pure CO2 of up to 11.81 MPa and 348.05 K were observed. Modeling of the fluid-phase equilibria for three of the four binary systems was done using the Peng–Robinson equation of state, standard van der Waals mixing rules with two binary interaction parameters, and a φ–φ formulation of the equilibrium. The binary interaction parameters were obtained by fitting the model to the experimental data. The model produced excellent agreement between computed and experimental data. Graphical representations of the modeling results are presented and compared to experimental results. The results indicate that the largest chlorosilane (diethyldichlorosilane) produced the largest shift in critical pressure and critical temperature with respect to pure CO2. 相似文献