全文获取类型
收费全文 | 9303篇 |
免费 | 567篇 |
国内免费 | 915篇 |
专业分类
化学 | 774篇 |
晶体学 | 5篇 |
力学 | 404篇 |
综合类 | 124篇 |
数学 | 3429篇 |
物理学 | 768篇 |
综合类 | 5281篇 |
出版年
2024年 | 15篇 |
2023年 | 67篇 |
2022年 | 112篇 |
2021年 | 102篇 |
2020年 | 150篇 |
2019年 | 190篇 |
2018年 | 163篇 |
2017年 | 204篇 |
2016年 | 224篇 |
2015年 | 219篇 |
2014年 | 367篇 |
2013年 | 502篇 |
2012年 | 540篇 |
2011年 | 570篇 |
2010年 | 484篇 |
2009年 | 553篇 |
2008年 | 586篇 |
2007年 | 710篇 |
2006年 | 595篇 |
2005年 | 512篇 |
2004年 | 482篇 |
2003年 | 451篇 |
2002年 | 397篇 |
2001年 | 301篇 |
2000年 | 264篇 |
1999年 | 272篇 |
1998年 | 237篇 |
1997年 | 229篇 |
1996年 | 198篇 |
1995年 | 155篇 |
1994年 | 141篇 |
1993年 | 118篇 |
1992年 | 103篇 |
1991年 | 128篇 |
1990年 | 87篇 |
1989年 | 73篇 |
1988年 | 61篇 |
1987年 | 51篇 |
1986年 | 27篇 |
1985年 | 21篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 25篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1973年 | 4篇 |
1972年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
罗元松 《四川大学学报(自然科学版)》2003,40(1):33-35
在Banach空间的框架下,研究了有限族非扩张映象隐迭代程序的收敛性,其结果不仅改进和发展了最新的有关结果,而且也肯定地回答了Xu提出的一个公开问题。 相似文献
62.
A. A. Tolstonogov 《Set-Valued Analysis》1998,6(2):129-147
Existence theorems of continuous selectors whose values are fixed points of multivalued contractions are proved. As an application, the existence of continuous selectors to generalized solution sets of partial differential inclusions, depending on a parameter, is obtained. 相似文献
63.
Pedro J. Torres 《Journal of Differential Equations》2007,232(1):277-284
In a periodically forced semilinear differential equation with a singular nonlinearity, a weak force condition enables the achievement of new existence criteria through a basic application of Schauder's fixed point theorem. The originality of the arguments relies in that, contrary to the customary situation in the available references, a weak singularity facilitates the arguments of the proofs. 相似文献
64.
Curtis Bennett Kathy J. Dempsey Bruce E. Sagan 《Journal of Algebraic Combinatorics》1994,3(3):261-283
We construct a family of partially ordered sets (posets) that are q-analogs of the set partition lattice. They are different from the q-analogs proposed by Dowling [5]. One of the important features of these posets is that their Whitney numbers of the first and second kind are just the q-Stirling numbers of the first and second kind, respectively. One member of this family [4] can be constructed using an interpretation of Milne [9] for S[n, k] as sequences of lines in a vector space over the Galois field F
q. Another member is constructed so as to mirror the partial order in the subspace lattice. 相似文献
65.
66.
通过对操作系统启动过程的深入研究,在WINDOWS98 DOS状态下,对当前大容量硬盘主引导扇区的引导过程进行了全面的剖析,导出扩展INT 13H读取大容量硬盘逻辑扇区的方法,这将对大容量硬盘的管理与维护十分有利。 相似文献
67.
本文根据成本性态法的思路.分析了影响可比产品成本降低额和降低率变动的因素,重点从理论上论证了产品品种结构的影响,并且合理地把单纯产量和品种结构对可比产品成本降低额(率)的影响分离开来. 相似文献
68.
Gyan Bhanot 《Journal of statistical physics》1990,60(1-2):55-75
I present a new method to exactly compute the partition function of a class of discrete models in arbitrary dimensions. The time for the computation for ann-state model on anL
d
lattice scales like
. I show examples of the use of this method by computing the partition function of the 2D Ising and 3-state Potts models for maximum lattice sizes 10×10 and 8×8, respectively. The critical exponentsv and and the critical temperature one obtains from these are very near the exactly known values. The distribution of zeros of the partition function of the Potts model leads to the conjecture that the ratio of the amplitudes of the specific heat below and above the critical temperature is unity. 相似文献
69.
P. J. Forrester 《Journal of statistical physics》1988,51(3-4):457-479
The Coulomb system consisting of an equal number of positive and negative charged rods confined to a one-dimensional lattice is studied. The grand partition function can be calculated exactly at two values of the coupling constant=q
2/k
B
T (q denoting the magnitude of the charges). The exact results lead to the conjecture that in the complex scaled fugacity plane, all the zeros of the grand partition function lie on the negative real axis for<2, on the point=–1 for=2, and on the unit circle for>2. In addition, for>4, we conjecture in general and prove at=4 that the zeros pinch the real axis in the thermodynamic limit, with an essential singularity in the pressure at the reduced density 1/2. 相似文献
70.
Multi-temperature thermal plasmas have often to be considered to account for the nonequilibrium effects. Recently André et al. have developed the calculation of concentrations in a multi-temperature plasma by artificially separating the partition functions into a product by assuming that the excitation energies are those of the lower levels (electronic, vibration, and rotation). However, at equilibrium, differences, increasing with temperature, can be observed between partition functions calculated rigorously and with their method. This paper presents a modified method where it has been assumed that the preponderant rotational energy is that of the vibrational level v=0 of the ground electronic state and the preponderant vibrational energy is that of the ground electronic state. The internal partition function can then be expressed as a product of series expressions. At equilibrium for N
2
and N
2
+
partition functions the values calculated with our method differ by less than 0.1% from those calculated rigorously. The calculation has been limited to three temperatures: heavy species Th
, electrons Te
, and vibrational T
v
temperatures. The plasma composition has been calculated by minimizing the Gibbs free enthalpy with the steepest descent numerical technique. The nonequilibrium properties have been calculated using the method of Devoto, modified by Bonnefoi and Aubreton. The ratio =Te/Th
was varied between 1 and 2 as well as the ratio
v
=T
v
/T
h
for a nitrogen plasma. At equilibrium the corresponding equilibrium transport properties of Ar and N
2
are in good agreement with those of Devoto and Murphy except for T>10,000 K where we used a different interaction potential for N–N
+
. The effects of v
and e
on thermodynamic and transport properties of N
2
are then discussed. 相似文献