全文获取类型
收费全文 | 246篇 |
免费 | 3篇 |
专业分类
化学 | 164篇 |
晶体学 | 7篇 |
力学 | 13篇 |
数学 | 21篇 |
物理学 | 44篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 7篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 3篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有249条查询结果,搜索用时 0 毫秒
91.
92.
Lewis acid–mediated arylation of N-protected 2/3-bromomethylindoles with different types of arenes is reported. 相似文献
93.
Macroreticular cation exchangers can be prepared by polymerizing sulfonated phenols with formaldehyde under acidic conditions. The resins are highly porous with large surface areas. Their properties compare well with those based on styrene and divinylbenzene copolymers. 相似文献
94.
95.
96.
This paper deals with the development and application of a new space curved frame finite element to be used for crash analysis (non-linear). The frame finite element has been developed using a mixed variational principle (complementary form) and using rotations as independent variables. The formulation has been validated for problems of large deflection and rotation, and for problems involving initially curved members. Based on the validation performed, it is expected that crash problems may be modelled using a single element per member thus retaining computational efficiency while performing an accurate analysis. An illustrative example (modelling of an S-leg seat) is presented here to illustrate the benefits of the proposed approach to a designer. 相似文献
97.
effect of horseradish peroxidase (HRP) and H2O2 concentrations on the removal efficiency of phenol, defined as the percentage of phenol removed from solution as a function
of time, has been investigated. When phenol and H2O2 react with an approximately one-to-one stoichiometry, the phenol is almost completely precipitated within 10 min. The reaction
is inhibited at higher concentrations of H2O2. The removal efficiency increases with an increase in the concentration of HRP, but an increase in the time of treatment
cannot be used to offset the reduction in removal efficiency at low concentrations of the enzyme, because of inactivation
of the enzyme. One molecule of HRP is needed to remove approximately 1100 molecules of phenol when the reaction is conducted
at pH 8.0 and at ambient temperature. 相似文献
98.
99.
Microwave-assisted preparation of dialkylimidazolium tetrachloroaluminates, [CnMIM][AlCl4] and their application as recyclable catalysts for the efficient and eco-friendly protection of alcohols as tetrahydropyranyl (THP) ethers are described. The same catalyst can also be utilized for the deprotection of THP ethers. 相似文献
100.
Cyclodextrin cavities have been grafted into a layered metal hydroxide to create hydrophobic nanopockets within the galleries of the inorganic solid. Neutral ferrocene molecules can be included within the grafted cavities by partitioning from a polar solvent to generate a new organometallic-organic-inorganic hybrid. The included ferrocene has been characterized by electronic and Raman spectroscopy. The capability of the cyclodextrin-functionalized solid to separate hydrophobic and hydrophilic derivatives of ferrocene is demonstrated. 相似文献