全文获取类型
收费全文 | 459879篇 |
免费 | 5097篇 |
国内免费 | 1348篇 |
专业分类
化学 | 245259篇 |
晶体学 | 6927篇 |
力学 | 19993篇 |
综合类 | 15篇 |
数学 | 52858篇 |
物理学 | 141272篇 |
出版年
2021年 | 3985篇 |
2020年 | 4367篇 |
2019年 | 4693篇 |
2018年 | 6163篇 |
2017年 | 6012篇 |
2016年 | 9242篇 |
2015年 | 5797篇 |
2014年 | 8987篇 |
2013年 | 21227篇 |
2012年 | 16599篇 |
2011年 | 20392篇 |
2010年 | 14318篇 |
2009年 | 14198篇 |
2008年 | 18616篇 |
2007年 | 18525篇 |
2006年 | 17124篇 |
2005年 | 15299篇 |
2004年 | 14232篇 |
2003年 | 12508篇 |
2002年 | 12336篇 |
2001年 | 14282篇 |
2000年 | 10729篇 |
1999年 | 8484篇 |
1998年 | 6978篇 |
1997年 | 6713篇 |
1996年 | 6430篇 |
1995年 | 5800篇 |
1994年 | 5685篇 |
1993年 | 5459篇 |
1992年 | 6119篇 |
1991年 | 6234篇 |
1990年 | 5950篇 |
1989年 | 5763篇 |
1988年 | 5784篇 |
1987年 | 5625篇 |
1986年 | 5352篇 |
1985年 | 6864篇 |
1984年 | 7009篇 |
1983年 | 5538篇 |
1982年 | 5635篇 |
1981年 | 5612篇 |
1980年 | 5167篇 |
1979年 | 5624篇 |
1978年 | 5764篇 |
1977年 | 5658篇 |
1976年 | 5593篇 |
1975年 | 5148篇 |
1974年 | 5116篇 |
1973年 | 5130篇 |
1972年 | 3664篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
271.
272.
273.
Z. Adonyi 《Journal of Thermal Analysis and Calorimetry》1994,42(2-3):491-503
Dimensionless number has been developed and introduced for quantitative analysis of the effect of thermogravimetric measuring factors like sample quantity, heating rate, etc. The TG, DTG and T data of different thermogravimetric measurements can be used directly for calculation of the three constants of analogy. TG data of CaCO3 measured in very different conditions show the method of transformation and its applicability for calculation of the correlation of measurements. 相似文献
274.
275.
276.
277.
Since the early demonstrations of our concept of pulsed microwave catalysis in chemistry, we have witnessed the coming of age of the technique as an enabling technology in the industrial world, despite the inadequate understanding of the basic mechanisms of how microwaves interact with metallic surface sites and the subsequent energy transfer. We shall present here some very recent developments of the microwave-induced acoustic technique and its applications to a better understanding of the basic surface heating and energy transfer phenomena in pulsed microwave catalytic systems. 相似文献
278.
279.
M. M. Eisl B. M. Reichl S. D. Böhmig H. Störi 《Fresenius' Journal of Analytical Chemistry》1994,349(1-3):194-196
Using a discrete model for the segregation kinetics based on the Darken theory of diffusion and on the regular solution model (RSM), one and two dimensional simulations of interface segregation in binary and ternary systems have been performed. The aim of the calculations was to investigate the kinetics of segregation sequences in ternary systems, the segregation kinetics in discrete systems during the initial phase and finally the kinetics of surface segregation in the region of a grain boundary intersected by the surface. 相似文献
280.
We report the NMR study of the liquid crystalline phases of aqueous solutions of the dye benzopurpurin (BP-4B). Upon changing dye concentration, the system exhibits a phase transition between two ordered phases at about 3·5 wt %. The structure of these phases was not determined but the evidence suggests that they consist of columns or helically twisted columns of stacked dye molecules which are randomly oriented, similar to nematic phases. 相似文献