全文获取类型
收费全文 | 17006篇 |
免费 | 2653篇 |
国内免费 | 1686篇 |
专业分类
化学 | 12370篇 |
晶体学 | 236篇 |
力学 | 856篇 |
综合类 | 101篇 |
数学 | 1966篇 |
物理学 | 5816篇 |
出版年
2024年 | 50篇 |
2023年 | 349篇 |
2022年 | 578篇 |
2021年 | 578篇 |
2020年 | 647篇 |
2019年 | 612篇 |
2018年 | 499篇 |
2017年 | 490篇 |
2016年 | 856篇 |
2015年 | 782篇 |
2014年 | 996篇 |
2013年 | 1241篇 |
2012年 | 1591篇 |
2011年 | 1604篇 |
2010年 | 998篇 |
2009年 | 954篇 |
2008年 | 1092篇 |
2007年 | 962篇 |
2006年 | 889篇 |
2005年 | 820篇 |
2004年 | 616篇 |
2003年 | 445篇 |
2002年 | 446篇 |
2001年 | 374篇 |
2000年 | 307篇 |
1999年 | 339篇 |
1998年 | 267篇 |
1997年 | 207篇 |
1996年 | 219篇 |
1995年 | 247篇 |
1994年 | 212篇 |
1993年 | 146篇 |
1992年 | 136篇 |
1991年 | 128篇 |
1990年 | 134篇 |
1989年 | 79篇 |
1988年 | 74篇 |
1987年 | 57篇 |
1986年 | 64篇 |
1985年 | 45篇 |
1984年 | 37篇 |
1983年 | 23篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
谐振子薛定谔方程的简单解法 总被引:2,自引:0,他引:2
物质的许多物理与化学性质都可以用线性谐振子模型解释,本文用简单的数学运算求解线性谐振子的薛定谔方程,避免了特殊函数等复杂的数学运算,得出了量子力学教材完全相同的结果。 相似文献
62.
Wang Dunhui Huang Songling Han Zhida Su Zhenghua Wang Yi Du Youwei 《Solid State Communications》2004,131(2):97-99
A series of Gd(1−x)Bx alloys have been prepared by arc melting method. After introducing small quantity of B atom in Gd, the Curie temperature of these alloys increase while the magnetic entropy changes are almost same as that of Gd. The refrigerant capacities of these alloys are also greater than that of Gd. These results suggest that Gd(1−x)Bx alloys may be utilized as refrigerant in household magnetic refrigeration. 相似文献
63.
In this paper, a construction of optimal constant composition codes is developed, and used to derive some series of new optimal
constant composition codes meeting the upper bound given by [13]. 相似文献
64.
65.
For given a graph H, a graphic sequence π = (d
1, d
2,..., d
n) is said to be potentially H-graphic if there is a realization of π containing H as a subgraph. In this paper, we characterize the potentially (K
5 − e)-positive graphic sequences and give two simple necessary and sufficient conditions for a positive graphic sequence π to
be potentially K
5-graphic, where K
r is a complete graph on r vertices and K
r-e is a graph obtained from K
r by deleting one edge. Moreover, we also give a simple necessary and sufficient condition for a positive graphic sequence
π to be potentially K
6-graphic.
Project supported by National Natural Science Foundation of China (No. 10401010). 相似文献
66.
For approximate wave functions, we prove the theorem that there is a one‐to‐one correspondence between the constraints of normalization and of the Fermi–Coulomb and Coulomb hole charge sum rules at each electron position. This correspondence is surprising in light of the fact that normalization depends on the probability of finding an electron at some position. In contrast, the Fermi–Coulomb hole sum rule depends on the probability of two electrons staying apart because of correlations due to the Pauli exclusion principle and Coulomb repulsion, while the Coulomb hole sum rule depends on Coulomb repulsion. We demonstrate the theorem for the ground state of the He atom by the use of two different approximate wave functions that are functionals rather than functions. The first of these wave function functionals is constructed to satisfy the constraint of normalization, and the second that of the Coulomb hole sum rule for each electron position. Each is then shown to satisfy the other corresponding sum rule. The significance of the theorem for the construction of approximate “exchange‐correlation” and “correlation” energy functionals of density functional theory is also discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
67.
Chii-Wann Lin Kuo-Ping Chen Ming-Chii Su Chih-Kung Lee Chih-Chung Yang 《Optical and Quantum Electronics》2005,37(13-15):1423-1437
We have reported a novel design of surface plasmon resonance (SPR) device, which uses alternating dielectric layers to enhance the SPR signal quality and modulate its resonant position. Admittance loci method of thin film design has been used in the design of such a device. The use of biomolecular thin film, such as DNAs or Porteins, in this design can result in resonant condition of wavelength changes as well. Bio-plasmonics is proposed for the research and development of novel devices, which use biomolecules as a part of the plasmon oscillation system to actively interact with nano/micro structure. 相似文献
68.
69.
70.
新疆野生黑加仑与马林果实的营养成分分析 总被引:2,自引:0,他引:2
通过对新疆野生黑加仑和野生马林的脂肪油,8种微量元素,17种氨基酸以及维生素C的含量进行测定得出:黑加仑脂肪油含量为17.9%,马林的脂肪油含量为22.3%,其中,黑加仑脂肪油中,r-亚麻酸的含量为19.02%,而马林中,其含量为9.40%,黑加仑中K,Na,Ca,Cu,Zn,Fe的含量比马林中的含量高,而Mn,Mg元素的含量却比马林含量低;马林的维生素C含量为16.22mg/g,黑加仑的含量为108mg/g,黑加仑的氨基酸的总量为1.63%,马林为1.14%。 相似文献