全文获取类型
收费全文 | 2525篇 |
免费 | 79篇 |
国内免费 | 29篇 |
专业分类
化学 | 1590篇 |
晶体学 | 10篇 |
力学 | 55篇 |
数学 | 545篇 |
物理学 | 433篇 |
出版年
2023年 | 10篇 |
2022年 | 14篇 |
2021年 | 86篇 |
2020年 | 41篇 |
2019年 | 56篇 |
2018年 | 55篇 |
2017年 | 48篇 |
2016年 | 97篇 |
2015年 | 74篇 |
2014年 | 108篇 |
2013年 | 190篇 |
2012年 | 177篇 |
2011年 | 185篇 |
2010年 | 126篇 |
2009年 | 123篇 |
2008年 | 143篇 |
2007年 | 161篇 |
2006年 | 147篇 |
2005年 | 152篇 |
2004年 | 122篇 |
2003年 | 83篇 |
2002年 | 60篇 |
2001年 | 24篇 |
2000年 | 25篇 |
1999年 | 24篇 |
1998年 | 18篇 |
1997年 | 23篇 |
1996年 | 24篇 |
1995年 | 25篇 |
1994年 | 20篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 20篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有2633条查询结果,搜索用时 15 毫秒
71.
Alexei Yu. Voronin Piotr Froelich Valery V. Nesvizhevsky 《Hyperfine Interactions》2012,213(1-3):129-135
We present a theoretical study of the motion of antihydrogen atoms in the Earth??s gravitational field near a material surface. We predict the existence of long-living quasistationary states of antihydrogen in a superposition of the gravitational and Casimir-van der Waals potentials of the surface. We suggest an interferometric method of measuring the energy difference between such gravitational states, hence the gravitational mass of antihydrogen. 相似文献
72.
73.
Piotr Frąckiewicz 《Physics letters. A》2018,382(48):3463-3469
The Li–Du–Massar quantum duopoly model is one of the generally accepted quantum game schemes. It has applications in a wide range of duopoly problems. Our purpose is to study Stackelberg's duopoly with incomplete information in the quantum domain. The result of Lo and Kiang has shown that the correlation of players' quantities caused by the quantum entanglement enhances the first-mover advantage in the game. Our work demonstrates that there is no first-mover advantage if the players' actions are maximally correlated. Furthermore, we proved that the second mover gains a higher equilibrium payoff than the first one. 相似文献
74.
Piotr T. Chruściel Erwann Delay Paul Klinger Andreas Kriegl Peter W. Michor Armin Rainer 《Letters in Mathematical Physics》2018,108(9):2009-2030
We prove existence of large families of solutions of Einstein-complex scalar field equations with a negative cosmological constant, with a stationary or static metric and a time-periodic complex scalar field. 相似文献
75.
Dr. Łukasz Mąkolski Vadim Szejko Dr. Karolina Zelga Dr. Adam Tulewicz Dr. Piotr Bernatowicz Dr. Iwona Justyniak Prof. Janusz Lewiński 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(18):5666-5674
Simple RZnOR’ alkoxides are among the first known organozinc compounds, and widespread interest in their multifaced chemistry has been driven by their fundamental significance and potential applications including various catalytic reactions. Nevertheless, their chemistry in solution and in the solid state remains both relatively poorly understood and a subject of constant debate. Herein, the synthesis and structural characterization of long-sought structural forms, a roof-like trimer [(tBuZn)3(μ-OC(H)Ph2)2(μ3-OC(H)Ph2)] and a ladder-type tetramer [(PhZn)4(μ-OC(H)Ph2)2(μ3-OC(H)Ph2)2], incorporating diphenylmethanolate as a model alkoxide ligand, are reported. Both novel aggregates are robust in the solid state and resistant towards mechanical force. By using 1H NMR and diffusion-order spectroscopy, it is demonstrated that new RZnOR’ alkoxides are kinetically labile in solution and readily undergo ligand scrambling, such as in the case of Schlenk equilibrium. The elucidated key structural issues, which have remained undiscovered for decades, significantly advance the chemistry of RZnOR’ alkoxides and should support the rational design of zinc alkoxide-based applications. 相似文献
76.
77.
Piotr Majewski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):151-154
Abstract The dialkylphosphinic acids, 5a-5e, can be obtained by reacting bis(trimethylsiloxy)phosphine with the highly reactive alkyl halides, 2a-2e, in the presence of chlorotrimethylsilane and triethylamine, followed by ethanolysis of the resulting trimethylsilyl dialkylphosphinates, 4a-4e. 相似文献
78.
79.
Piotr Kozlowski Silvia D. Chang Ran Meng Burkhard Mädler Robert Bell Edward C. Jones S. Larry Goldenberg 《Magnetic resonance imaging》2010
The purpose of this work was to compare diagnostic accuracy of Diffusion Tensor Imaging (DTI), dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and their combination in diagnosing prostate cancer. Twenty-five patients with clinical suspicion of prostate cancer underwent MRI, prior to transrectal ultrasound-guided biopsies. MRI data were correlated to biopsy results. Logistic regression models were constructed for the DTI parameters, DCE MRI parameters, and their combination. The areas under the receiver operator characteristic curves (AUC) were compared between the models. The nonparametric Wilcoxon signed rank test was used for statistical analysis. The sensitivity and specificity values were respectively 81% (74–87%) and 85% (79–90%) for DTI and 63% (55–70%) and 90% (85–94%) for DCE. The combination “DTI or DCE MRI” had 100% (97–100%) sensitivity and 77% (69–83%) specificity, while “DTI and DCE MRI” had 44% (37–52%) sensitivity and 98% (94–100%) specificity. The AUC for DTI+DCE parameters was significantly higher than that for either DTI (0.96 vs. 0.92, P=.0143) or DCE MRI parameters (0.96 vs. 0.87, P=.00187) alone. In conclusion, the combination of DTI and DCE MRI has significantly better accuracy in prostate cancer diagnosis than either technique alone. 相似文献
80.
This review describes the state of the art in the field of polyoxometalates containing noble metal atoms (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold). The structures of the various species are listed together with their applications (mainly in catalysis). 相似文献