全文获取类型
收费全文 | 2172篇 |
免费 | 113篇 |
国内免费 | 7篇 |
专业分类
化学 | 1460篇 |
晶体学 | 2篇 |
力学 | 54篇 |
数学 | 420篇 |
物理学 | 356篇 |
出版年
2023年 | 53篇 |
2022年 | 42篇 |
2021年 | 66篇 |
2020年 | 108篇 |
2019年 | 86篇 |
2018年 | 28篇 |
2017年 | 53篇 |
2016年 | 103篇 |
2015年 | 83篇 |
2014年 | 84篇 |
2013年 | 94篇 |
2012年 | 133篇 |
2011年 | 149篇 |
2010年 | 76篇 |
2009年 | 56篇 |
2008年 | 116篇 |
2007年 | 90篇 |
2006年 | 89篇 |
2005年 | 73篇 |
2004年 | 56篇 |
2003年 | 48篇 |
2002年 | 52篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 11篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1992年 | 9篇 |
1989年 | 8篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1977年 | 13篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1970年 | 8篇 |
1968年 | 9篇 |
1967年 | 8篇 |
1934年 | 11篇 |
1933年 | 8篇 |
1930年 | 8篇 |
1905年 | 7篇 |
1881年 | 9篇 |
排序方式: 共有2292条查询结果,搜索用时 15 毫秒
971.
This paper presents analytical results for higher moments of characteristics of a Voronoi tessellation generated by a homogeneous Poisson point process in the three-dimensional Euclidean space. The second moment of the volume of the typical cell as well as higher moments for the edge length distribution and the linear contact distribution are given. These characteristics are calculated analytically and presented in a unified form. 相似文献
972.
We continue the work of various authors on the stability and error structure of multistep schemes applied to linear evolution equations. BDF schemes are considered, and, as far as reasonable, explicit expressions for all occurring bounds are specified, exploiting prior work on the location of characteristic roots. The 2-step BDF scheme is considered in particular detail, and for problems of sectorial type, an asymptotic error expansion is derived based on damping properties of the scheme. 相似文献
973.
Mateus Feitosa Alves Larissa Adilis Maria Paiva Ferreira Francisco Allysson Assis Ferreira Gadelha Laércia Karla Diega Paiva Ferreira Mayara Barbalho Felix 《Natural product research》2019,33(6):789-795
The ethanolic extract of the leaves of Cissampelos sympodialis showed great pharmacological potential, with inflammatory and immunomodulatory activities, however, it showed some toxicological effects. Therefore, this study aims to verify the toxicological potential of alkaloids of the genus Cissampelos through in silico methodologies, to develop a method in LC-MS/MS verifying the presence of alkaloids in the infusion and to evaluate the toxicity of the infusion of the leaves of C. sympodialis when inhaled by Swiss mice. Results in silico showed that alkaloid 93 presented high toxicological potential along with the products of its metabolism. LC-MS/MS results showed that the infusion of the leaves of this plant contained the alkaloids warifteine and methylwarifteine. Finally, the in vivo toxicological analysis of the C. sympodialis infusion showed results, both in biochemistry, organ weights and histological analysis, that the infusion of C. sympodialis leaves presents a low toxicity. 相似文献
974.
975.
Nunuparov Armen Becker Felix Bolotnik Nikolay Zeidis Igor Zimmermann Klaus 《Archive of Applied Mechanics (Ingenieur Archiv)》2019,89(10):2193-2208
Archive of Applied Mechanics - Non-classical locomotion systems have the perspective for a wide application in the vast fields of bio-medical and maintenance technology. Capsule bots are small,... 相似文献
976.
Felix Schroeter Johannes Soellner Dr. Thomas Strassner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(10):2527-2537
We present a new class of tunable aryl alkyl ionic liquids (TAAILs) containing different palladate counter ions. Solid-state structures for representative compounds have been obtained. Their properties are presented in comparison to those of newly synthesized and reported palladate ionic liquids with conventional counter ions. It was found that the aryl substitution pattern and the type of anion have a profound influence on the melting point. The speciation of the different anions in solution has been rationalized by DFT calculations. 相似文献
977.
Wei‐Tse Lee Antoine P. vanMuyden Felix D. Bobbink Zhangjun Huang Paul J. Dyson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):567-570
We report a ruthenium‐modified zeolite which efficiently transforms propylene carbonate to propylene glycol and methane, under solvent‐free conditions. The catalyst achieved high product selectivity and no significant ageing effect was observed after multiple cycles. The resulting liquid product (water‐containing glycol) can be directly used as anti‐freeze solution and the gas phase can directly be used as an energy carrier in the form of H2‐enriched methane. This process efficiently bridges energy storage and an important chemical synthesis under sustainable (CO2 consuming) conditions. 相似文献
978.
979.
980.
Felix Zandman 《Experimental Mechanics》1962,2(8):225-233
With the photoelastic stress gage birefringence readings are made with light that traverses a path parallel to the surface of the workpiece. Individual stresses are determined in the elastic range of deformation, rather than stress or strain differences. The theory of a circular and linear stress gage is developed, including the influence of Poisson's ratio, and stress gradients. Stresses in the surface of the workpiece are expressed in terms of measured birefringence. Instrumentation is extremely simple. High sensitivity is derived from the relatively long optical-path length through the transducer. Applications should include stress analysis, load analysis and transducer design. 相似文献