全文获取类型
收费全文 | 679篇 |
免费 | 24篇 |
国内免费 | 8篇 |
专业分类
化学 | 432篇 |
晶体学 | 4篇 |
力学 | 14篇 |
数学 | 124篇 |
物理学 | 137篇 |
出版年
2023年 | 4篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 24篇 |
2015年 | 15篇 |
2014年 | 8篇 |
2013年 | 31篇 |
2012年 | 25篇 |
2011年 | 44篇 |
2010年 | 20篇 |
2009年 | 23篇 |
2008年 | 46篇 |
2007年 | 30篇 |
2006年 | 45篇 |
2005年 | 40篇 |
2004年 | 43篇 |
2003年 | 30篇 |
2002年 | 19篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1988年 | 7篇 |
1986年 | 3篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 12篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1965年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有711条查询结果,搜索用时 15 毫秒
71.
72.
Angular distributions of high energy He nuclei, emitted from the target in central 16O-AgBr interactions, are found to be highly forward-peaked at 0.2 GeV/nucleon but almost isotropic at 2 GeV/nucleon. The angular distributions are in qualitative agreement with recent shock-wave calculations. However, we observe no narrow peaks neither in the angular nor in the energy distributions of He nuclei. 相似文献
73.
Anders Hallberg Arnold R. Martin Gary E. Martin Gunnar Grönberg 《Journal of heterocyclic chemistry》1984,21(6):1893-1895
13C-nmr chemical shift assignments for 5H-Indolo[1,7-ab][1]benzazepine and 6,7-Dihydro-5H-indolo-[1,7-ab][1]benzazepine, made on the basis of two-dimensional 1H-13C chemical shift correlation experiments are reported. 相似文献
74.
75.
Andreas Rudolf Mats Galbe Gunnar Lidén 《Applied biochemistry and biotechnology》2004,114(1-3):601-617
Inhibitors formed during wood hydrolysis constitute a major problem in fermenting dilute-acid hydrolysates. By applying a
fed-batch technique, the levels of inhibitory compounds may be held low, enabling high ethanol productivity. In this study,
a previously developed fed-batch strategy was modified and implemented for use in pilot development unit (PDU) scale. The
rate of total gas formation, measured with a mass flow meter, was used as input variable in the control algorithm. The feed
rate in the PDU-scale experiments could be properly controlled based on the gas evolution from the reactor. In fed-batch experiments
utilizing TMB 3000, an inhibitor-tolerant strain of Saccharomyces cerevisiae, close to 100% of the hexoses in the hydrolysate was converted. 相似文献
76.
77.
The shallow water wave equation is derived in a general deforming co-ordinate system. A weak form is developed which displays the natural boundary condition prominently and which may be implemented on C0 elements. A time-stepping algorithm is implemented with clastic mapping of interior node motion. Lossless test cases show agreement with analytic solutions. A simple hypothetical test case shows intuitively good behaviour at length scales approaching those required of estuarine simulations. 相似文献
78.
79.
Gunnar Karlström Bo Jönsson Björn O. Roos Per E. M. Siegbahn 《Theoretical chemistry accounts》1978,48(1):59-74
SCF-CI calculations have been performed on a number of chemical reactions between closed shell molecules in order to determine the heats of reaction. Contracted Gaussian type atomic basis sets of three different qualities were used and the CI calculations were performed in a truncated approximate natural orbital space. The conclusions to be drawn from these calculations are rather pessimistic. For heats of reaction, errors up to 6 kcal/mole are obtained on the SCF-level with a double zeta plus polarization atomic basis. A further improvement is only possible if extended basis sets are used. Correlation effects on heats of reaction are of the same size and CI calculations are therefore only meaningful with large atomic basis sets.For the CI calculations a one-electron space of approximate natural orbitals, obtained from second order RS perturbation theory, was used. Different truncations, using the occupation number as criterion, were tested. The general conclusion is that errors in energy differences obtained with a truncated basis set are of the same magnitude as the error in the total correlation energy. In practice this means that not more than 20–30% of the approximate natural orbitals can be deleted if the error is to be kept less than a few kcal/mole.Finally the truncation error in calculations of bond distances was tested for a few cases. Errors of around 10% of the total change due to correlation were found when 30% of the lowest occupied natural orbitals were deleted. 相似文献
80.
Rogers CJ Mee JM Kaufmann GF Dickerson TJ Janda KD 《Journal of the American Chemical Society》2005,127(28):10016-10017
Cocaine is among the most reinforcing of all drugs of abuse, yet no effective pharmacotherapy is available. Herein, we report the development and characterization of phage-displayed cocaine esterases with pharmacologically relevant kinetic parameters (kcat/Km approximately 104 M-1 s-1). 相似文献