全文获取类型
收费全文 | 10054篇 |
免费 | 176篇 |
国内免费 | 38篇 |
专业分类
化学 | 5754篇 |
晶体学 | 85篇 |
力学 | 352篇 |
数学 | 1632篇 |
物理学 | 2445篇 |
出版年
2022年 | 95篇 |
2021年 | 111篇 |
2020年 | 122篇 |
2019年 | 123篇 |
2018年 | 117篇 |
2017年 | 102篇 |
2016年 | 178篇 |
2015年 | 159篇 |
2014年 | 165篇 |
2013年 | 566篇 |
2012年 | 353篇 |
2011年 | 438篇 |
2010年 | 318篇 |
2009年 | 272篇 |
2008年 | 397篇 |
2007年 | 357篇 |
2006年 | 348篇 |
2005年 | 317篇 |
2004年 | 336篇 |
2003年 | 271篇 |
2002年 | 273篇 |
2001年 | 187篇 |
2000年 | 178篇 |
1999年 | 144篇 |
1998年 | 114篇 |
1997年 | 131篇 |
1996年 | 161篇 |
1995年 | 120篇 |
1994年 | 122篇 |
1993年 | 152篇 |
1992年 | 154篇 |
1991年 | 158篇 |
1990年 | 116篇 |
1989年 | 119篇 |
1988年 | 131篇 |
1987年 | 180篇 |
1986年 | 148篇 |
1985年 | 196篇 |
1984年 | 184篇 |
1983年 | 144篇 |
1982年 | 166篇 |
1981年 | 176篇 |
1980年 | 171篇 |
1979年 | 170篇 |
1978年 | 164篇 |
1977年 | 162篇 |
1976年 | 141篇 |
1975年 | 158篇 |
1974年 | 126篇 |
1973年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Mari Grobbelaar‐Van Dalsen 《Mathematical Methods in the Applied Sciences》2005,28(4):443-455
In this paper a model for the vibrations of a one‐dimensional hybrid thermo‐elastic structure consisting of an extensible thermo‐elastic beam which is hinged at one end, with a rigid body attached to its free end, is studied with a view to establishing the existence of a unique solution in a weak sense. The model takes account of the effect of stretching on bending and rotational inertia. By treating eigenvalue problems with the spectral parameter also in the boundary conditions, we are able to employ the method of Faedo–Galerkin approximations. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
992.
Inneke Van Nieuwenhuyse Nico Vandaele Kumar Rajaram Uday S. Karmarkar 《European Journal of Operational Research》2007
This paper studies the impact of management policies, such as product allocation and campaign sizing, on the required size of the finished goods inventories in a multi-product multi-reactor batch process. Demand, setup and batch processing times for these products are assumed to be stochastic, and the inventory buffer for every product type needs to be such that target customer service levels are met. To perform this analysis, we develop a queueing model that allows us to explicitly estimate service levels as a function of the buffer size, and the allocation/campaign sizing policies. This model can be used to evaluate the service level given an existing buffer configuration, as well as to determine the buffer sizes required across products to meet a pre-specified service level. It also allows us to formulate a number of insights into how product allocation decisions and campaign planning policies affect buffer sizing decisions in symmetric production systems. 相似文献
993.
Steven Swier Kurt Van Durme Bruno Van Mele 《Journal of Polymer Science.Polymer Physics》2003,41(15):1824-1836
The heat capacity or reversing heat flow signal from modulated‐temperature differential scanning calorimetry can be used to measure the onset of phase separation in a poly(vinylmethylether)/water mixture, clearly showing the special type III lower critical solution temperature demixing behavior. Characteristic of this demixing behavior is a three‐phase region, which is detected in the nonreversing heat flow signal. Stepwise quasi‐isothermal measurements through the phase transition show large excess contributions in the (apparent) heat capacity signal, caused by demixing/remixing heat effects on the timescale of the modulation (fast process). These excess contributions and their time‐dependent evolutions (slow process) are useful in understanding the kinetics of phase separation and the morphology (interphase) development. Care has to be taken, however, in interpreting the heat capacity signal derived from the amplitude of the modulated heat flow because nonlinear effects lead to the occurrence of higher harmonics. Therefore, the raw heat flow signal for quasi‐isothermal demixing and remixing measurements is also examined in the time domain. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1824–1836, 2003 相似文献
994.
995.
Necessary and sufficient conditions for the existence of a complex structure in an 8-dimensional spin vector bundle over a
closed connected spin manifold of dimension 8 are given in terms of characteristic classes. The result completes the papers
by Heaps [H] and Thomas [T] on the same topic.
Received: 2 May 1997 相似文献
996.
997.
Xavier Pannecoucke Alain Van Dorsselaer Bang Luu 《Journal of mass spectrometry : JMS》1992,27(2):140-144
Negative-ion fast atom bombardment mass spectra of five compounds resulting from combinations between oxysterols and nucleoside analogues linked by phosphodiester bonds are presented and interpreted. This method seems to be the most appropriate for elucidating the structure of these complex, labile and non-volatile phosphate-containing molecules which exhibit important antitumour and/or immunosuppressive activities. 相似文献
998.
999.
Ulrich Meier Christoph Van Wüllen Michael Schindler 《Journal of computational chemistry》1992,13(5):551-559
A direct method for the ab initio calculation of the magnetic susceptibility and chemical shielding tensors based on the individual gauge for localized molecular orbitals (IGLO) formalism is introduced. “Direct” in this context means we avoid storing the two-electron repulsion integrals in favor of recalculating them whenever necessary. In conjunction with the Direct-SCF package TURBOMOLE Direct IGLO (DIGLO) permits calculation of magnetic second-order properties for large molecules by minimizing peripheral disc storage requirements. The size of the molecules to be treated is limited only by the amount of CPU time available. The performance of DIGLO is demonstrated for some selected examples. 相似文献
1000.