全文获取类型
收费全文 | 9278篇 |
免费 | 1343篇 |
国内免费 | 1032篇 |
专业分类
化学 | 6850篇 |
晶体学 | 104篇 |
力学 | 469篇 |
综合类 | 110篇 |
数学 | 1205篇 |
物理学 | 2915篇 |
出版年
2024年 | 13篇 |
2023年 | 165篇 |
2022年 | 194篇 |
2021年 | 281篇 |
2020年 | 344篇 |
2019年 | 329篇 |
2018年 | 258篇 |
2017年 | 276篇 |
2016年 | 445篇 |
2015年 | 404篇 |
2014年 | 553篇 |
2013年 | 712篇 |
2012年 | 850篇 |
2011年 | 859篇 |
2010年 | 606篇 |
2009年 | 538篇 |
2008年 | 607篇 |
2007年 | 520篇 |
2006年 | 448篇 |
2005年 | 372篇 |
2004年 | 355篇 |
2003年 | 320篇 |
2002年 | 345篇 |
2001年 | 271篇 |
2000年 | 170篇 |
1999年 | 213篇 |
1998年 | 137篇 |
1997年 | 109篇 |
1996年 | 129篇 |
1995年 | 97篇 |
1994年 | 99篇 |
1993年 | 89篇 |
1992年 | 76篇 |
1991年 | 77篇 |
1990年 | 46篇 |
1989年 | 52篇 |
1988年 | 34篇 |
1987年 | 31篇 |
1986年 | 34篇 |
1985年 | 31篇 |
1984年 | 10篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1966年 | 6篇 |
1963年 | 7篇 |
1959年 | 12篇 |
1958年 | 13篇 |
1957年 | 15篇 |
1956年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
81.
Many sets of the soliton and periodic travelling wave solutions for the quadratic χ^(2) nonlinear system are obtained by the Backlund transformation and the trial method. The property of the propagation for some travelling waves is investigated. 相似文献
82.
热效应对光折变晶体两波耦合的特性影响的理论分析 总被引:3,自引:1,他引:2
用一种模型对两波耦合进行了分析,导出了强度相位的解析式,对影响两波耦合的参数进行了理论分析。分析了对BaTiO3光折变晶体的两波耦合的测量结果。 相似文献
83.
从实验上探讨了掺Nd^3+的氟化物玻璃光纤正向双程超荧光基本特性,包括输入-输出特性、输出-带宽特性以及输出-波长(激发)特性。并给出了理论上的拟合公式,实验表明利用氟化物玻璃光纤有望获得性能优异的有应用前景的低相干度集成化光源。 相似文献
84.
This paper presents some results of the relation between wavelet transform and fractal transform. The wavelet transform of the attractor of fractal transform posseses translational and scale invariance. So we speed the fractal image encoding by testing the invariance of the wavelet transform appropriate for image encoding. The classfication scheme of range blocks by wavelet transform is given in this paper. 相似文献
85.
86.
JiŘí Kvapil Josef Kvapil Bohumil Perner Michal Košelja Helena Jelínková 《Czechoslovak Journal of Physics》1990,40(11):1283-1287
The methods of growing YAG:Nd crystals with a flat interface and YAP:Nd crystals with a sharp conical interface are described. The form of the interface was controlled by the He and H2O content in the reducing atmosphere composed mainly of Ar and H2 as well as by axial temperature gradient above the melt level. The crystals of 120–180 mm in length were machined to the high-quality slabs. 相似文献
87.
88.
Mariano Giaquinta Giuseppe Modica Jiří souček 《Archive for Rational Mechanics and Analysis》1989,106(2):97-159
Summary In this paper we introduce some new classes of functions, among these a class of weak diffeomorphisms. In these classes we prove by direct methods the existence of minimizers for several kinds of variational integrals. In particular, we prove the existence of one-to-one orientation-preserving maps that minimize suitable energies associated with hyperelastic materials. The minimizers are also proved to satisfy equilibrium equations. Finally radial deformations are discussed in connection with cavitation. 相似文献
89.
Mária Hvastijová Jiří Kohout Helmut Köhler 《Monatshefte für Chemie / Chemical Monthly》1992,123(6-7):493-500
Summary New dicyanamide complexes of the typeM[N(CN)2]2
L
2 (M=Cu or Ni;L=2-, 3-, 4-aminopyridine, 2-amino-5-nitropyridine) and Co[N(CN)2]2 (2-amino-5-nitropyridine)2 were prepared and studied by spectroscopic methods as well as by room-temperature magnetic moments. The results show that the Cu(II) complexes have elongated pseudooctahedral structures while the Ni(II) and Co(II) complexes are octahedral. In most cases the N(CN)2 groups are in bridging function and through their cyanide nitrogens, or-more rarely-amide and cyanide nitrogens connect the basic structure units into polymeric conglomerates. In the Cu(II) systems exchange coupling is seen from the eff value or ESR spectrum.
Professor Viktor Gutmann zum 70. Geburtstag gewidmet 相似文献
90.
Chemically modified electrodes prepared by treating the cobalt tetraphenylporphyrin modified glassy-carbon electrode at 750 degrees (HCME) are shown to catalyze the electrooxidation of hydrazine. The oxidation occurred at +0.63 V vs. Ag/AgCl (saturated potassium chloride) in pH 2.5 media. The catalytic response is evaluated with respect to solution pH, potential scan-rate, concentration dependence and flow-rate. The catalytic stability of the HCME is compared with that of the cobalt tetraphenylporphyrin adsorbed glassy-carbon electrode. The stability of the HCME was excellent in acidic solution and even in solutions containing organic solvent (50% CH(3)OH). When used as the sensing electrode in amperometric detection in flow-injection analysis, the HCME permitted sensitive detection of hydrazine at 0.5 V. The limit of detection was 0.1 ng. The linear range was from 50 ng to 2.4 mug. The method is very sensitive and selective. 相似文献