全文获取类型
收费全文 | 20116篇 |
免费 | 1477篇 |
国内免费 | 2854篇 |
专业分类
化学 | 14319篇 |
晶体学 | 202篇 |
力学 | 1457篇 |
综合类 | 250篇 |
数学 | 1438篇 |
物理学 | 6781篇 |
出版年
2024年 | 29篇 |
2023年 | 261篇 |
2022年 | 450篇 |
2021年 | 387篇 |
2020年 | 572篇 |
2019年 | 485篇 |
2018年 | 418篇 |
2017年 | 553篇 |
2016年 | 564篇 |
2015年 | 513篇 |
2014年 | 738篇 |
2013年 | 1531篇 |
2012年 | 1158篇 |
2011年 | 1110篇 |
2010年 | 894篇 |
2009年 | 1096篇 |
2008年 | 1112篇 |
2007年 | 1254篇 |
2006年 | 1073篇 |
2005年 | 1089篇 |
2004年 | 996篇 |
2003年 | 753篇 |
2002年 | 649篇 |
2001年 | 620篇 |
2000年 | 1363篇 |
1999年 | 1010篇 |
1998年 | 945篇 |
1997年 | 367篇 |
1996年 | 352篇 |
1995年 | 334篇 |
1994年 | 294篇 |
1993年 | 243篇 |
1992年 | 217篇 |
1991年 | 164篇 |
1990年 | 126篇 |
1989年 | 95篇 |
1988年 | 82篇 |
1987年 | 65篇 |
1986年 | 51篇 |
1985年 | 62篇 |
1984年 | 51篇 |
1983年 | 24篇 |
1982年 | 45篇 |
1981年 | 51篇 |
1980年 | 32篇 |
1979年 | 33篇 |
1978年 | 27篇 |
1977年 | 33篇 |
1976年 | 22篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Bandcrossing in 31 rotational bands of 25 different odd-A nuclei in the rare-earth region has been analysed by using a two-band mixing formalism with a constant band interaction within
the framework of the effective decoupling picture. The interband interaction strengthV between the one-quasiparticle band and the three-quasiparticle band exhibits a variation with the neutron number which is
not different from the oscillatory behaviour observed in even-even nuclei and does not show signs of any appreciable phase
shifting as predicted by theory. However, the overall range of variation ofV is greater than that observed in even-even systems. 相似文献
82.
LIU Biao BAO Yong-li WEI Zhuang WU Yin MENG Xiang-ying LI Yu-xin YIN Wei-tian 《高等学校化学研究》2006,22(2):217-220
Introduction Activinisamemberofthetransforminggrowth factor(TGF)βsuperfamilyofextracellularsignaling proteins.Themembersofthisfamilyplayacriticalrole duringembryogenesisandinmaintainingtissuehomeo stasisinadultlife[1—3].DeregulatedTGFfamilysigna lingisi… 相似文献
83.
WANG Jiang-yun GU Wen WANG Wen-zhen LIU Xin LIAO Dai-zheng 《高等学校化学研究》2006,22(3):283-286
Introduction Itiswell knownthatcyanogroupsincyanometa latessuchas[Ag(CN)2]-unitscanbeusedasbridg ingligandsandapolymericstructurecanbeformed throughsilver silver(argentophilic)interactions.This propertyhasbeenexploredintheconstructionofmany oligomericandp… 相似文献
84.
This paper analyses and models the dynamic interaction among permeable multi-cracks in a piezoelectric strip under anti-plane shear waves by the Schmidt method. The Fourier transform is applied and then two pairs of triple integral equations can be solved using the Schmidt method. The results show that the stress and the electric displacement intensity factors of cracks depend on not only the crack length and the piezoelectric coefficient, but also the thickness of the piezoelectric strip, the distance between multi-cracks and the frequency of incident wave. 相似文献
85.
利用莫尔条纹的准正弦特性的三维轮廓术 总被引:5,自引:0,他引:5
分析了两个矩形光栅迭合产生的莫尔条纹的光强分布特性,通过选择适当的光栅参数,可得到一个近似的正弦分划板,并把它用于三维面形测量中,实验结果表明,这种方法简单,易于自动处理,有广泛的实用价值。 相似文献
86.
An acoustic pulse propagating on a two-mode fiber can act as a beam splitter in a scanning interferometer. When this device
is employed in white-light interferometry, the effects of distributed coupling and dispersive interferometer arms need to
be considered. A theory suitable for treating acousto-optic interaction of partially coherent light in a moving interaction
region was developed. It was found that differential optical dispersion should be negligible and the acoustic pulse length
short. Also the coherence time should be short but long compared to the intermodal group delay difference over a pulse length.
Experiments with long acoustic pulses were performed, and fairly good agreement with theory was obtained. 相似文献
87.
A fifth-order theory for solving the problem of interaction between Stokes waves and exponential profile currents is proposed.
The calculated flow fields are compared with measurements. Then the errors caused by the linear superposition method and approximate
theory are discussed. It is found that the total wavccurrent field consists of pure wave, pure current and interaction components.
The shear current not only directly changes the flow field, but also indirectly does so by changing the wave parameters due
to wave-current interaction. The present theory can predict the wave kinematics on shear currents satisfactorily. The linear
superposition method may give rise to more than 40% loading error in extreme conditions. When the apparent wave period is
used and the Wheeler stretching method is adopted to extrapolate the current, application of the approximate theory is the
best.
Project supported by the Chinese Academy of Sciences. 相似文献
88.
89.
用三维样边界元法分析水闸闸室结构。底板,闸墩和载水墙等为其子结构,交通桥,工作桥和胸墙等处理为内部支撑。地基和边载可以是任意的,只要能给定地表位移面力关系。在各种工况下,不论是设置平板门还是弧形门,是平底板是反拱底板,即使在稀疏剖分下也能给出高精度的位移场,应力场和地基反力场。 相似文献
90.