全文获取类型
收费全文 | 2510篇 |
免费 | 132篇 |
国内免费 | 16篇 |
专业分类
化学 | 1591篇 |
晶体学 | 9篇 |
力学 | 110篇 |
数学 | 602篇 |
物理学 | 346篇 |
出版年
2024年 | 3篇 |
2023年 | 25篇 |
2022年 | 30篇 |
2021年 | 49篇 |
2020年 | 50篇 |
2019年 | 41篇 |
2018年 | 50篇 |
2017年 | 24篇 |
2016年 | 84篇 |
2015年 | 97篇 |
2014年 | 97篇 |
2013年 | 159篇 |
2012年 | 231篇 |
2011年 | 229篇 |
2010年 | 142篇 |
2009年 | 150篇 |
2008年 | 162篇 |
2007年 | 192篇 |
2006年 | 164篇 |
2005年 | 147篇 |
2004年 | 120篇 |
2003年 | 95篇 |
2002年 | 93篇 |
2001年 | 36篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 14篇 |
1997年 | 16篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 19篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1920年 | 1篇 |
1909年 | 2篇 |
1903年 | 1篇 |
1895年 | 1篇 |
1891年 | 2篇 |
1890年 | 2篇 |
1889年 | 1篇 |
排序方式: 共有2658条查询结果,搜索用时 265 毫秒
141.
Jacqueline Destain Patrick Fickers Frédéric Weekers Benoît Moreau Philippe Thonart 《Applied biochemistry and biotechnology》2005,121(1-3):269-277
In this article, we report the development and optimization of an industrial culture medium for the production of extracellular
lipase in the yeast Yarrowia lipolytica. Until now olive oil in combination with glucose was used as the carbon source and inducer for the production of lipase.
Our results demonstrate that methyloleate, a cheap hydrophobic compound, could efficiently substitute olive oil as the inducer
and carbon source for lipase production. A new process of lipase production was developed yielding a twofold increase in the
level of production compared with the levels in previous reports. 相似文献
142.
Eddy Thiriot Sébastien Canneaux Eric Hénon Frédéric Bohr 《Reaction Kinetics and Catalysis Letters》2005,85(1):123-129
Summary We show the presence of an ether group in alkoxy radicals significantly lowers the activation energy of the b-C-H dissociation and only slightly increases the isomerization barrier. Moreover, an 1-6 isomerization mechanism involving a 7-membered transition state may compete with the usual 1-5 isomerization. 相似文献
143.
144.
145.
The fundamental bands of the CCl3 asymmetric deformation modes of selected isotopomers of chloroform (CHCl3) and freon-11 (CFCl3) have been measured in a static cell at ambient temperature using a laser-based source of tunable radiation in the terahertz region of the electromagnetic spectrum. The analysis of the rotational contours of the bands enabled the derivation of the fundamental frequencies with an accuracy of better than 3 GHz. 相似文献
146.
We design a perfectly matched layer for the advection–diffusion equation. We show that the reflection coefficient is exponentially small with respect to the damping parameter and the width of the PML and independently of the advection and of the viscosity parameters. Numerical tests assess the efficiency of the approach. 相似文献
147.
148.
149.
Éric Cancès Geneviève Dusson Yvon Maday Benjamin Stamm Martin Vohralík 《Comptes Rendus Mathematique》2014,352(11):941-946
In this Note, we propose a new method, based on perturbation theory, to post-process the planewave approximation of the eigenmodes of periodic Schrödinger operators. We then use this post-processing to construct an accurate a posteriori estimator for the approximations of the (nonlinear) Gross–Pitaevskii equation, valid at each step of a self-consistent procedure. This allows us to design an adaptive algorithm for solving the Gross–Pitaevskii equation, which automatically refines the discretization along the convergence of the iterative process, by means of adaptive stopping criteria. 相似文献
150.
Mohammad Alaghemandi Joachim Schulte Frédéric Leroy Florian Müller‐plathe Michael C. Böhm 《Journal of computational chemistry》2011,32(1):121-133
The thermal conductivity (λ) of carbon nanotubes (CNTs) with chirality indices (5,0), (10,0), (5,5), and (10,10) has been studied by reverse nonequilibrium molecular dynamics (RNEMD) simulations as a function of different bond length alternation patterns (Δri). The Δri dependence of the bond force constant (krx) in the molecular dynamics force field has been modeled with the help of an electronic band structure approach. These calculations show that the Δri dependence of krx in tubes with not too small a diameter can be mapped by a simple linear bond length–bond order correlation. A bond length alternation with an overall reduction in the length of the nanotube causes an enhancement of λ, whereas an alternation scheme leading to an elongation of the tube is coupled to a decrease of the thermal conductivity. This effect is more pronounced in carbon nanotubes with larger diameters. The formation of a polyene‐like structure in the direction of the longitudinal axis has a negligible influence on λ. A comparative analysis of the RNEMD and crystal orbital results indicates that Δri‐dependent modifications of λ and the electrical conductivity are uncorrelated. This behavior is in‐line with a heat transfer that is not carried by electrons. Modifications of λ as a function of the bond alternation in the (10,10) nanotube are explained with the help of power spectra, which provide access to the density of vibrational states. We have suggested longitudinal low‐energy modes in the spectra that might be responsible for the Δri dependence of λ. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献