全文获取类型
收费全文 | 3417篇 |
免费 | 123篇 |
国内免费 | 14篇 |
专业分类
化学 | 2209篇 |
晶体学 | 20篇 |
力学 | 121篇 |
数学 | 673篇 |
物理学 | 531篇 |
出版年
2023年 | 17篇 |
2022年 | 61篇 |
2021年 | 87篇 |
2020年 | 36篇 |
2019年 | 74篇 |
2018年 | 48篇 |
2017年 | 69篇 |
2016年 | 114篇 |
2015年 | 103篇 |
2014年 | 94篇 |
2013年 | 207篇 |
2012年 | 192篇 |
2011年 | 207篇 |
2010年 | 124篇 |
2009年 | 113篇 |
2008年 | 205篇 |
2007年 | 169篇 |
2006年 | 196篇 |
2005年 | 170篇 |
2004年 | 122篇 |
2003年 | 129篇 |
2002年 | 89篇 |
2001年 | 50篇 |
2000年 | 43篇 |
1999年 | 46篇 |
1998年 | 32篇 |
1997年 | 34篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 36篇 |
1993年 | 41篇 |
1992年 | 30篇 |
1991年 | 20篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 42篇 |
1984年 | 36篇 |
1983年 | 41篇 |
1982年 | 29篇 |
1981年 | 23篇 |
1980年 | 31篇 |
1979年 | 24篇 |
1977年 | 24篇 |
1976年 | 18篇 |
1975年 | 18篇 |
1974年 | 13篇 |
1973年 | 15篇 |
排序方式: 共有3554条查询结果,搜索用时 31 毫秒
111.
Villagomez-Guzman Ana K. Rodriguez-Garcia Gabriela del Rio Rosa E. Oliveros Ortiz Antonio J. Cerda-Garcia-Rojas Carlos M. Joseph-Nathan Pedro Gomez-Hurtado Mario A. 《Chemistry of Natural Compounds》2021,57(2):319-322
Chemistry of Natural Compounds - A known kaurenoic acid (1), together with a new kaurane derivative named 3α-isobutyryloxykaurenoic acid (2), was isolated from the roots of Lasianthaea aurea,... 相似文献
112.
113.
114.
Mario Lamberger Florian Mendel Vincent Rijmen Koen Simoens 《Designs, Codes and Cryptography》2012,62(1):1-18
We investigate generic methods to find near-collisions in cryptographic hash functions. We introduce a new generic approach
based on methods to find cycles in the space of codewords of a code with low covering radius. We give an analysis of our approach
and demonstrate it on the SHA-3 candidate TIB3. 相似文献
115.
116.
117.
118.
119.
Mario Jug Francesca Maestrelli Paola Mura 《Journal of inclusion phenomena and macrocyclic chemistry》2012,74(1-4):87-97
β-Cyclodextrin (βCD) and its soluble polymeric derivative (EPIβCD) were used to improve the effectiveness of chitosan-based bucco-adhesive film formulations containing bupivacaine hydrochloride and triclosan as poorly-soluble model drugs. The film formulations were characterized in terms of swelling, mucoadhesion and in vitro drug release, while possible interactions between the components were investigated by DSC and FTIR analyses. For both drugs EPIβCD showed a higher solubilizing efficiency than βCD; however cyclodextrin effectiveness in improving the release rate from film formulations was influenced by their different interactions with chitosan. Free βCD acted as a channelling agent, favouring the film swelling, while EPIβCD due to interaction with chitosan caused an opposite effect. βCD was the optimal partner for bupivacaine-loaded films in terms of film swelling, mucoadhesion and drug release. Contrariwise, EPIβCD was the best partner for triclosan-loaded films, allowing the highest drug release rate increase, due to its higher solubilizing ability with respect to βCD. Addition of the suitable cyclodextrin enabled formulation of buccal films with suitable drug release properties. 相似文献
120.
We prove that a given Calabi-Yau threefold with a stable holomorphic vector bundle can be perturbed to a solution of the Strominger system provided that the second Chern class of the vector bundle is equal to the second Chern class of the tangent bundle. If the Calabi-Yau threefold has strict SU(3) holonomy then the equations of motion derived from the heterotic string effective action are also satisfied by the solutions we obtain. 相似文献