全文获取类型
收费全文 | 13426篇 |
免费 | 2610篇 |
国内免费 | 2865篇 |
专业分类
化学 | 10752篇 |
晶体学 | 322篇 |
力学 | 759篇 |
综合类 | 245篇 |
数学 | 1504篇 |
物理学 | 5319篇 |
出版年
2024年 | 38篇 |
2023年 | 246篇 |
2022年 | 531篇 |
2021年 | 585篇 |
2020年 | 599篇 |
2019年 | 629篇 |
2018年 | 516篇 |
2017年 | 572篇 |
2016年 | 684篇 |
2015年 | 728篇 |
2014年 | 918篇 |
2013年 | 1145篇 |
2012年 | 1268篇 |
2011年 | 1290篇 |
2010年 | 1049篇 |
2009年 | 1019篇 |
2008年 | 1115篇 |
2007年 | 961篇 |
2006年 | 907篇 |
2005年 | 752篇 |
2004年 | 555篇 |
2003年 | 439篇 |
2002年 | 417篇 |
2001年 | 381篇 |
2000年 | 289篇 |
1999年 | 235篇 |
1998年 | 191篇 |
1997年 | 141篇 |
1996年 | 107篇 |
1995年 | 98篇 |
1994年 | 89篇 |
1993年 | 66篇 |
1992年 | 60篇 |
1991年 | 57篇 |
1990年 | 54篇 |
1989年 | 43篇 |
1988年 | 26篇 |
1987年 | 16篇 |
1986年 | 22篇 |
1985年 | 15篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1965年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
用光学多通道分析仪系统作高分辨光谱测量的技术 总被引:1,自引:0,他引:1
通常的光多通道分析仪(OMA)存在着同时谱宽与分辨率的矛盾.本文所述方法,在不减小谱宽的前提下,可将该分析仪光谱分辨率提高1~2量级,使之可适用于高分辨率谱研究. 相似文献
62.
63.
关于可达矩阵的求法探讨 总被引:6,自引:0,他引:6
在《离散数学》、《图论》课程中 ,用矩阵表示图时 ,涉及到一类重要的矩阵——可达矩阵 ,它是判别图中任意两点是否有通路的重要手段 ,也是求强分图的重要方法 ,但是可达矩阵的求法比较复杂 .本文针对这一问题 ,对可达矩阵的求法进行了改进 ,提出了一种简单可行的算法 . 相似文献
64.
65.
We investigate a spatial Prisoner's Dilemma game with nonlinear attractive effect on regular small-world networks. The players located on the sites of networks can either cooperate with their neighbours or defect. In every generation, each player updates its strategy by firstly choosing one of the neighbours with a probability proportional to .A^α denoting the attractiveness of the neighbour, where .4 is the collected payoff and ^α (-〉0) is a free parameter characterizing the extent of nonlinear effect. Then each player adopts its strategy with a probability dependent on their payoff difference. Using Monte Carlo simulations, we investigate the density pc of cooperators in the stationary state for various values of α and the rewiring probability q of the network. It is shown that the introduction of such attractive effect remarkably promotes the emergence and persistence of cooperation over a wide range of the temptation to defect for the same network structures. We also point out that long-range connections either enhance or inhibit the cooperation, which depends on the value of α and the payoff parameter b. 相似文献
66.
67.
The fission barrier for ^240pu is investigated beyond the second saddle point in the potentiM energy surface by the constrained relativistic mean field method with the newly proposed parameter set PK1. The microscopic correction for the centre-of-mass motion is essentiM to provide the correct potential energy surface. The shell effects that stabilize the nuclei against the fission is also investigated by the Strutinsky method. The shapes for the ground state, fission isomer and saddle-points, etc, are studied in detail. 相似文献
68.
In this note we study constant mean curvature surfaces in asymptotically flat 3-manifolds. We prove that, outside a given compact subset in an asymptotically flat 3-manifold with positive mass, stable spheres of given constant mean curvature are unique. Therefore we are able to conclude that the foliation of stable spheres of constant mean curvature in an asymptotically flat 3-manifold with positive mass outside a given compact subset is unique.
69.
Incident intensity, defined by the amount of particles deposited per pulse, is an important parameter in the film growth process of pulsed laser deposition (PLD). Different from previous models, we investigate the irreversible and reversible growth processes by using a kinetic Monte Carlo method and find that island density and film morphology strongly depend on pulse intensity. At higher pulse intensities, lots of adatoms instantaneously diffuse on the substrate surface, and then nucleation easily occurs between the moving adatoms resulting in more smaller-size islands. In contrast, at the lower pulse intensities, nucleation event occurs preferentially between the single adatom and existing islands rather than forming new islands, and therefore the average island size becomes larger in this case. Additionally, our results show that substrate temperature plays an important role in film growth. In particular, it can determine the films shape and weaken the effect of pulse intensity on film growth at the lower temperatures by controlling the mobility rate of atoms. Our results can match the related theoretical and experimental results. 相似文献
70.