全文获取类型
收费全文 | 1729篇 |
免费 | 119篇 |
国内免费 | 35篇 |
专业分类
化学 | 1123篇 |
晶体学 | 7篇 |
力学 | 47篇 |
数学 | 352篇 |
物理学 | 354篇 |
出版年
2023年 | 23篇 |
2022年 | 35篇 |
2021年 | 57篇 |
2020年 | 67篇 |
2019年 | 84篇 |
2018年 | 72篇 |
2017年 | 53篇 |
2016年 | 102篇 |
2015年 | 63篇 |
2014年 | 79篇 |
2013年 | 115篇 |
2012年 | 132篇 |
2011年 | 129篇 |
2010年 | 80篇 |
2009年 | 62篇 |
2008年 | 77篇 |
2007年 | 86篇 |
2006年 | 68篇 |
2005年 | 60篇 |
2004年 | 44篇 |
2003年 | 25篇 |
2002年 | 38篇 |
2001年 | 17篇 |
2000年 | 21篇 |
1999年 | 12篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 15篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有1883条查询结果,搜索用时 334 毫秒
1.
Giang Truong Nguyen Prof. Dr. Liviu Ungur 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202200227
Employing radical bridges between anisotropic metal ions has been a viable route to achieve high-performance single-molecule magnets (SMMs). While the bridges have been mainly considered for their ability to promote exchange interactions, the crystal-field effect arising from them has not been taken into account explicitly. This lack of consideration may distort the understanding and limit the development of the entire family. To shed light on this aspect, herein we report a theoretical investigation of a series of N -radical-bridged diterbium complexes. It is found that while promoting strong exchange coupling between the terbium ions, the N -radical induces a crystal field that interferes destructively with that of the outer ligands, and thus reduces the overall SMM behavior. Based on the theoretical results, we conclude that the SMM behavior in this series could be further maximized if the crystal field of the outer ligands is designed to be collinear with that of the radical bridge. This conclusion can be generalized to all exchange-coupled SMMs. 相似文献
2.
Bao Nguyen Xuan Duy Khanh Phan Quoc Tung Nguyen Minh 《Set-Valued and Variational Analysis》2022,30(2):465-486
Set-Valued and Variational Analysis - We aim to establish Karush-Kuhn-Tucker multiplier rules involving higher-order complementarity slackness under Hölder metric subregularity. These rules... 相似文献
3.
Applying tight-binding approximation and spin pairing of like charge carriers in a pair of excitons created in a lattice, the possibility of forming a bound exciton-exciton state is studied. It is found that, provided there exists strong exciton-lattice interaction, such a bound state may be formed and its energy may lie within the valence band deforming the material into a crystalline solid with no energy gap. Lowering of the energy is calculated in naphthalene and anthracene crystals where some experimental results are known. The excess energy released after the formation of such bound state can be adequate, depending on the material, to desorb neutral atoms or eject of electrons from surfaces. 相似文献
4.
The deposition of decomposed ethylene on silicon wafer at lower temperature using hot filament chemical vapor deposition (HFCVD) method was applied to compose thin film of carbon and its compounds with silicon and hydrocarbon structures. The films were analyzed using Raman spectroscopy, X-ray diffraction, and scanning electron microscopy with elemental microanalysis by energy dispersive X-ray spectrometer. The structure and morphology of the early stage of the film deposition was analyzed. The obtaining of SiC as well as diamond-like structure with this method and catalytic influence of chemical admixtures on the film structure and properties are discussed. 相似文献
5.
6.
Mitsunori Oda Yosuke Fukuchi Satoshi Ito Nguyen Chung Thanh Shigeyasu Kuroda 《Tetrahedron letters》2007,48(52):9159-9162
Reactions of pyrrolidine with 2 equiv of aldehydes without any catalyst in a pressurized vessel at 140–200 °C yielded 1,3-disubstituted pyrroles. -Branched aldehydes gave fairly good yields of the corresponding products by this method, which provides a facile non-oxidative procedure for synthesizing 1,3-dialkylpyrroles from inexpensive pyrrolidine and aldehydes. 相似文献
7.
We calculate one-loop radiative QCD corrections to the three polarized and unpolarized structure functions that determine the beam-quark polar angle dependence of the longitudinal polarization of light and heavy quarks produced in e+e?-annihilations. We present analytical and numerical results for the longitudinal polarization and its polar angle dependence. We discuss in some detail the zero-mass limit of our results and the role of the anomalous spin-flip contributions to the polarization observables in the zero-mass limit. Our discussion includes transverse and longitudinal beam polarization effects. 相似文献
8.
9.
Application of the refined Wiener-Hermite expansion with moderate to high Reynolds numbers Re to homogeneous, isotropic turbulence is presented. The results show a defect to Kolmogorov's five-thirds law, increase in the absolute value of the exponent comparable with many theoretical predictions. Midrange spectra up to fluctuation Reynolds numbers of 108 show little, if any, dependence of the defect on Re, as long as the initial spectra do not deviate too far from their equilibrium states. The renormalization scheme has also been proven to have no effect on the final shape of the spectrum. 相似文献
10.