全文获取类型
收费全文 | 18191篇 |
免费 | 3314篇 |
国内免费 | 1659篇 |
专业分类
化学 | 12646篇 |
晶体学 | 175篇 |
力学 | 1019篇 |
综合类 | 68篇 |
数学 | 2025篇 |
物理学 | 7231篇 |
出版年
2024年 | 17篇 |
2023年 | 391篇 |
2022年 | 410篇 |
2021年 | 598篇 |
2020年 | 731篇 |
2019年 | 735篇 |
2018年 | 713篇 |
2017年 | 565篇 |
2016年 | 954篇 |
2015年 | 819篇 |
2014年 | 1050篇 |
2013年 | 1380篇 |
2012年 | 1708篇 |
2011年 | 1765篇 |
2010年 | 1171篇 |
2009年 | 1091篇 |
2008年 | 1204篇 |
2007年 | 1052篇 |
2006年 | 993篇 |
2005年 | 791篇 |
2004年 | 604篇 |
2003年 | 415篇 |
2002年 | 401篇 |
2001年 | 323篇 |
2000年 | 259篇 |
1999年 | 369篇 |
1998年 | 264篇 |
1997年 | 285篇 |
1996年 | 277篇 |
1995年 | 240篇 |
1994年 | 207篇 |
1993年 | 211篇 |
1992年 | 142篇 |
1991年 | 158篇 |
1990年 | 130篇 |
1989年 | 99篇 |
1988年 | 88篇 |
1987年 | 69篇 |
1986年 | 68篇 |
1985年 | 54篇 |
1984年 | 57篇 |
1983年 | 31篇 |
1982年 | 32篇 |
1981年 | 24篇 |
1980年 | 27篇 |
1978年 | 13篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1973年 | 15篇 |
1968年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
31.
采用量子统计系综理论,研究了基态NO分子宏观气体摩尔熵、摩尔内能、摩尔热容等热力学性质.首先应用课题组前期建立的变分代数法(variational algebraic method, VAM)计算获得了基态NO分子的完全振动能级,得到的VAM振动能级作为振动部分,结合欧拉-麦克劳林渐进展开公式的转动贡献,应用于经典的热力学与统计物理公式中,从而计算得到了1000-5000 K温度范围内NO宏观气体的摩尔内能、摩尔熵和摩尔热容.将不同方法计算得到的摩尔热容结果分别与实验值进行比较,结果表明基于VAM完全振动能级获得的结果优于其他方法获得的理论结果.振动部分采用谐振子模型对无限能级求和计算热力学性质的方法有一定的局限性,应当使用有限的完全振动能级进行统计求和. 相似文献
32.
33.
34.
35.
Nonlinear Dynamics - Darboux and Bäcklund transformations on integrable couplings are formulated and generalized. The generalization of the theory pertains to spectral problems where the... 相似文献
36.
In this paper, we construct a high-order moving mesh method based on total variation diminishing Runge-Kutta and weighted essential nonoscillatory reconstruction for compressible fluid system. Beginning with the integral form of fluid system, we get the semidiscrete system with an arbitrary mesh velocity. We use weighted essential nonoscillatory reconstruction to get the space accuracy on moving meshes, and the time accuracy is obtained by modified Runge-Kutta method; the mesh velocity is determined by moving mesh method. One- and two-dimensional numerical examples are presented to demonstrate the efficient and accurate performance of the scheme. 相似文献
37.
Raspberry-like (RB) nanoparticles hold potential for diverse applications due to their hierarchical morphology. Here we developed a novel tandem synthetic approach of nonsynchronous growth based on photo-mediated reversible-deactivation radical polymerization, enabling simple, efficient and bottom-up synthesis of RB nanoparticles of uniform sizes at quantitative conversions of fluorinated monomers. Chain transfer agents of different chain lengths, concentrations and chemical compositions were varied to tune the diameter of RB particles. Importantly, fluorinated RB nanoparticles obtained with this method allow facile post modifications via both covalent bond formation and intermolecular physical interactions without disrupting the RB morphology. The facile nature of this method and versatility of the obtained fluorinated RB materials open new opportunities for the development of functional materials using nanoparticles.Nonsynchronous growth of raspberry-like (RB) nanoparticles in a one-pot and bottom-up fashion, enabling simple post-modification of RB colloids through both covalent bond formation and supramolecular interaction. 相似文献
38.
Nonlinear Dynamics - Fault features extraction method for slight misalignment of rotor systems is researched in this paper. When a rotor system with faults is excited by harmonic inputs, system... 相似文献
39.
Lens-less Fourier-transform holography has been actively studied because of its simple optical structure and its single-shot recording.However,a low-contrast interferogram between the reference and object waves limits its signal to noise ratio.Here,multi-reference lens-less Fourier-transform holography with a Greek-ladder sieve array is proposed in the experiment and demonstrated effectively to improve the signal to noise ratio.The key technique in our proposed method is a Greek-ladder sieve array,which acts as not only a wave-front modulator but also a beam splitter.With advantages of the common path,single shot,and no need for a lens,this system has enormous potential in imaging and especially in extreme ultraviolet and soft X-ray holography. 相似文献
40.