全文获取类型
收费全文 | 1494篇 |
免费 | 28篇 |
国内免费 | 8篇 |
专业分类
化学 | 766篇 |
晶体学 | 14篇 |
力学 | 46篇 |
数学 | 318篇 |
物理学 | 386篇 |
出版年
2022年 | 10篇 |
2021年 | 19篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2017年 | 14篇 |
2016年 | 33篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 86篇 |
2012年 | 61篇 |
2011年 | 76篇 |
2010年 | 39篇 |
2009年 | 39篇 |
2008年 | 58篇 |
2007年 | 65篇 |
2006年 | 66篇 |
2005年 | 56篇 |
2004年 | 63篇 |
2003年 | 32篇 |
2002年 | 37篇 |
2001年 | 30篇 |
2000年 | 26篇 |
1999年 | 22篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 29篇 |
1995年 | 19篇 |
1994年 | 37篇 |
1993年 | 32篇 |
1992年 | 19篇 |
1991年 | 25篇 |
1990年 | 33篇 |
1989年 | 19篇 |
1988年 | 29篇 |
1987年 | 17篇 |
1986年 | 20篇 |
1985年 | 33篇 |
1984年 | 25篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 26篇 |
1980年 | 13篇 |
1979年 | 18篇 |
1978年 | 16篇 |
1977年 | 10篇 |
1976年 | 20篇 |
1975年 | 9篇 |
1974年 | 17篇 |
1973年 | 14篇 |
1972年 | 9篇 |
排序方式: 共有1530条查询结果,搜索用时 15 毫秒
941.
Mariela M. Nolasco Mariana Matos Coimbra Stewart F. Parker Pedro D. Vaz Paulo J. A. Ribeiro-Claro 《Molecules (Basel, Switzerland)》2022,27(21)
In this work, the structural dynamics of the chloromethanes CCl4, CHCl3 and CH2Cl2 were evaluated through a computational spectroscopy approach by comparing experimental inelastic neutron scattering (INS) spectra with the corresponding simulated spectra obtained from periodic DFT calculations. The overall excellent agreement between experimental and calculated spectra allows a confident assignment of the vibrational features, including not only the molecular fundamental modes but also lattice and combination modes. In particular, an impressive overtone sequence for CHCl3 is fully described by the simulated INS spectrum. In the CCl4 spectrum, the splitting of the ν3 mode at ca. 765–790 cm−1 is discussed on the basis of the Fermi resonance vs. crystal splitting controversy. 相似文献
942.
Stephanie Chapman Dr. Alexander J. O'Malley Dr. Ivana Miletto Dr. Marina Carravetta Dr. Paul Cox Prof. Enrica Gianotti Leonardo Marchese Dr. Stewart F. Parker Prof. Robert Raja 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(42):9938-9947
Soft templating with siliceous surfactant is an established protocol for the synthesis of hierarchically porous silicoaluminophosphates (HP SAPOs) with improved mass transport properties. Motivated by the enhanced performance of HP SAPOs in the Beckmann rearrangement of cyclohexanone oxime to the nylon 6 precursor ϵ-caprolactam, an integrated theoretical and empirical study was carried out to investigate the catalytic potential of the siliceous mesopore network. Inelastic neutron scattering (INS) studies, in particular, provided unique insight into the substrate-framework interactions in HP (Si)AlPOs and allowed reactive species to be studied independent of the catalyst matrix. The spectroscopic (INS, FTIR spectroscopy, MAS NMR spectroscopy) and computational analyses revealed that in the organosilane-templated SAPO, the interconnectivity of micro- and mesopores permits cooperativity between their respective silanol and Brønsted acid sites that facilitates the protonation of cyclohexanone oxime in a physical mixture at ambient temperature. 相似文献
943.
José M. Carcione Liu Xu Greenhalgh Stewart Botelho Marco A. B. Ba Jing 《Acoustical Physics》2020,66(6):598-603
Acoustical Physics - We first compare two apparently dissimilar expressions for the quality factor Q of inhomogeneous plane waves in isotropic viscoelastic media, where Q is defined as the result... 相似文献
944.
Fenske Emilie K. Roach Benjamin D. Hexel Cole R. Glasgow David C. Stewart Ian R. Partridge John D. Giaquinto Joseph M. 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(2):759-771
Journal of Radioanalytical and Nuclear Chemistry - Analysis of irradiated material shortly after irradiation can be non-trivial due to highly radioactive activation and fission isotopes increasing... 相似文献
945.
946.
Aboufaris EL Alaoui S. M. Ghallali L. EL Guendouzi M. Benbiyi A. 《Journal of solution chemistry》2022,51(7):802-815
Journal of Solution Chemistry - In this investigation, calculated and experimental solubilities of the binary aqueous solutions of dipotassium hydrogenphosphate and disodium hydrogenphosphate have... 相似文献
947.
948.
Romy E. MartinMarta E. Polomska Lindsay T. ByrneScott G. Stewart 《Tetrahedron letters》2011,52(38):4878-4881
Herein we describe the efficient stereoselective preparation of C8 substituted indolizidines bearing a 6-methylene group, from the chiral pool starting material l-proline. This synthesis, employing a Tsuji-Trost reaction as the key step, represents a potentially, efficient route to pumiliotoxin natural product epimers. 相似文献
949.
Seán M. Stewart 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(3):232-238
A new method based on the polylogarithm function is used to derive an exact expression for the fractional emissive power of a blackbody in any arbitrary spectral band. Compared to all previously used methods the polylogarithm based method is unsurpassed in its simplicity. Displacement laws for the centroid of blackbody radiation in the linear wavelength and frequency spectral representations that make use of the polylogarithm based approach are also given. 相似文献
950.
Nicole A. Cohen Michelle L. Stewart Evripidis Gavathiotis Jared L. Tepper Susanne R. Bruekner Brian Koss Joseph T. Opferman Loren D. Walensky 《Chemistry & biology》2012,19(9):1175-1186
- Download : Download high-res image (218KB)
- Download : Download full-size image