全文获取类型
收费全文 | 1266篇 |
免费 | 26篇 |
国内免费 | 3篇 |
专业分类
化学 | 911篇 |
晶体学 | 11篇 |
力学 | 9篇 |
综合类 | 2篇 |
数学 | 174篇 |
物理学 | 188篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 13篇 |
2016年 | 18篇 |
2015年 | 19篇 |
2014年 | 20篇 |
2013年 | 60篇 |
2012年 | 51篇 |
2011年 | 72篇 |
2010年 | 39篇 |
2009年 | 39篇 |
2008年 | 80篇 |
2007年 | 64篇 |
2006年 | 49篇 |
2005年 | 73篇 |
2004年 | 56篇 |
2003年 | 56篇 |
2002年 | 42篇 |
2001年 | 34篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 17篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 17篇 |
1994年 | 20篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 22篇 |
1983年 | 9篇 |
1982年 | 19篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 18篇 |
1978年 | 20篇 |
1977年 | 13篇 |
1976年 | 25篇 |
1975年 | 6篇 |
1974年 | 10篇 |
1973年 | 15篇 |
排序方式: 共有1295条查询结果,搜索用时 15 毫秒
91.
Phase transition of the layer structure of poly(p-benzenedithiol-co-p-diethylbenzene) obtained in solid state polymerization was studied by a thermal treatment or UV irradiation under a nitrogen atmosphere. The peak intensities in the X-ray diffraction diagram of polymers gradually decreased with the thermal treatment time above 55°C. Below 50°C the layer structure of polymers hardly changed. The apparent activation energy for the phase transition was about 15 Kcal/mol [63 KJ/mol] at the initial stage and gradually decreased to a few Kcal/mol [ca. 2 KJ/mol]. UV light from a high-pressure mercury lamp also gradually induced the phase transition from the layer structure to an amorphous one. The pristine polymer possesses phase transition points at 75, 95 and 130°C. The exothermic transition at 75°C can be understood as the thermal destruction of the semistable layer structure. The exothermic transition at 95°C may be correspond to the cis → trans thermal isomerization of the C?°C bond in the polymer main chain. The diffuse reflectance spectrum of the pristine polymer differed from that of the amorphous polymer obtained by the thermal treatment of the pristine polymer. SEM photographs of the pristine polymer showed a particular surface structure, i.e. entangled fibrous material. TEM photographs of the pristine polymer exhibited a bright valley-and-hill structure, whereas that of the amorphous polymer obtained by thermal treatment exhibited a plain surface. 相似文献
92.
93.
A globally convergent Newton method for solving strongly monotone variational inequalities 总被引:14,自引:0,他引:14
Variational inequality problems have been used to formulate and study equilibrium problems, which arise in many fields including economics, operations research and regional sciences. For solving variational inequality problems, various iterative methods such as projection methods and the nonlinear Jacobi method have been developed. These methods are convergent to a solution under certain conditions, but their rates of convergence are typically linear. In this paper we propose to modify the Newton method for variational inequality problems by using a certain differentiable merit function to determine a suitable step length. The purpose of introducing this merit function is to provide some measure of the discrepancy between the solution and the current iterate. It is then shown that, under the strong monotonicity assumption, the method is globally convergent and, under some additional assumptions, the rate of convergence is quadratic. Limited computational experience indicates the high efficiency of the proposed method. 相似文献
94.
Summary It is shown that certain singular integral operators with variable kernels leave invariant theL
v,
-spaces studied by Campanato, Stampacchia, Peetre and others. Our results extend Peetre's work on convolution operators. 相似文献
95.
Eiichi Bannai 《Journal of Algebraic Combinatorics》1993,2(4):327-344
We introduce the concept of fusion algebras at algebraic level, as a purely algebraic concept for the fusion algebras which appear in conformal field theory in mathematical physics. We first discuss the connection between fusion algebras at algebraic level and character algebras, a purely algebraic concept for Bose-Mesner algebras of association schemes. Through this correspondence, we establish the condition when the matrix S of a fusion algebra at algebraic level is unitary or symmetric. We construct integral fusion algebras at algebraic level, from association schemes, in particular from group association schemes, whose matrix S is unitary and symmetric. Finally, we consider whether the modular invariance property is satisfied or not, namely whether there exists a diagonal matrix T satisfying the condition (ST)3 = S
2. We prove that this property does not hold for some integral fusion algebras at algebraic level coming from the group association scheme of certain groups of order 64, and we also prove that the (nonintegral) fusion algebra at algebraic level obtained from the Hamming association scheme H(d, q) has the modular invariance property. 相似文献
96.
We consider a problem of allocating indivisible objects when agents may desire to consume more than one object and no monetary
transfers are allowed. We are interested in allocation rules that satisfy desirable properties from an economic and social
point of view. In addition to strategy-proofness and Pareto efficiency, we consider consistency and two solidarity properties
(replacement-domination and population-monotonicity). In most of the cases, these properties are satisfied only by serially
dictatorial rules.
Received: November 1999/Final version: December 2001 相似文献
97.
Deringoz Fatih Guliyev Vagif S. Nakai Eiichi Sawano Yoshihiro Shi Minglei 《Positivity》2019,23(3):727-757
Positivity - In the present paper, we will characterize the boundedness of the generalized fractional integral operators $$I_{rho }$$ and the generalized fractional maximal operators $$M_{rho }$$... 相似文献
98.
We consider the stochastic linear complementarity problem (SLCP) involving a random matrix whose expectation matrix is positive semi-definite. We show that the expected residual minimization (ERM) formulation of this problem has a nonempty and bounded solution set if the expected value (EV) formulation, which reduces to the LCP with the positive semi-definite expectation matrix, has a nonempty and bounded solution set. We give a new error bound for the monotone LCP and use it to show that solutions of the ERM formulation are robust in the sense that they may have a minimum sensitivity with respect to random parameter variations in SLCP. Numerical examples including a stochastic traffic equilibrium problem are given to illustrate the characteristics of the solutions. 相似文献
99.
Eiichi Nakai 《Journal of Mathematical Analysis and Applications》2006,313(2):730-737
Chang, Krantz and Stein [D.-C. Chang, S.G. Krantz, E.M. Stein, Hp theory on a smooth domain in Rn and elliptic boundary value problems, J. Funct. Anal. 114 (1993) 286-347] proved that if f∈Hp(Rn) and f vanishes outside , then f has an atomic decomposition whose atoms are contained in Ω. The purpose of this paper is to give another proof for the case n/(n+1)<p?1 and Ω a cube. Our argument provides a simple, direct construction of the desired atomic decomposition, and it works in a class of function spaces more general than the usual Hardy spaces. 相似文献
100.
The multi-leader-follower game can be looked on as a generalization of the Nash equilibrium problem and the Stackelberg game,
which contains several leaders and a number of followers. Recently, the multi-leader-follower game has been drawing more and
more attention, for example, in electricity power markets. However, when we formulate a general multi-leader-follower game
as a single-level game, it will give rise to a lot of problems, such as the lack of convexity and the failure of constraint
qualifications. In this paper, to get rid of these difficulties, we focus on a class of multi-leader-follower games that satisfy
some particular, but still reasonable assumptions, and show that these games can be formulated as ordinary Nash equilibrium
problems, and then as variational inequalities. We establish some results on the existence and uniqueness of a leader-follower
Nash equilibrium. We also present illustrative numerical examples from an electricity power market model. 相似文献