全文获取类型
收费全文 | 1138篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
化学 | 1003篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 73篇 |
物理学 | 104篇 |
出版年
2023年 | 6篇 |
2022年 | 20篇 |
2021年 | 21篇 |
2020年 | 28篇 |
2019年 | 16篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 37篇 |
2015年 | 22篇 |
2014年 | 44篇 |
2013年 | 46篇 |
2012年 | 82篇 |
2011年 | 82篇 |
2010年 | 57篇 |
2009年 | 34篇 |
2008年 | 56篇 |
2007年 | 61篇 |
2006年 | 49篇 |
2005年 | 60篇 |
2004年 | 44篇 |
2003年 | 34篇 |
2002年 | 49篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1987年 | 10篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1982年 | 11篇 |
1980年 | 9篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1975年 | 7篇 |
1973年 | 9篇 |
1962年 | 6篇 |
1947年 | 6篇 |
1937年 | 4篇 |
1935年 | 5篇 |
1928年 | 5篇 |
1920年 | 4篇 |
排序方式: 共有1193条查询结果,搜索用时 15 毫秒
101.
Negative electrorheological responses induced by micro-particle electrorotation in two-dimensional Couette flow geometries are analyzed by a set of continuum modeling field equations originating from anti-symmetric/couple stress theories in the finite spin viscosity small spin velocity (FSV) limit. Analytical solutions are obtained for the first time to express the spin velocity, linear velocity, and effective viscosity in terms of the electric field strength, driving shear rate, boundary condition selection parameter, and spin viscosity. Good agreement is achieved between the FSV theoretical predictions presented herein and the experimental measurements reported in recent literature for the effective viscosity for low driving shear rates. 相似文献
102.
103.
Vinyl polymerized norbornene has some useful properties such as good mechanical strength, optical transparency and heat resistance. Several transition metal complexes have been described in the literature as active catalysts for the vinyl polymerization of norbornene. We now report the use of three types of nickel(II) complexes with N‐heterocyclic carbene (NHC) ligands in the catalytic vinyl polymerization of norbornene under a range of conditions. Specifically, two nickel complexes bearing a chelating bis(NHC) ligand, two nickel complexes bearing two chelating anionic N‐donor functionalized NHC ligands as well as one diiodidonickel(II) complex with two monodentate NHC ligands were tested. The solid‐state structure of bis(1,3‐dimethylimidazol‐2‐ylidene)diiodidonickel(II), as determined by X‐ray crystallography, is presented. The highest polymerization activity of 2.6 × 107 g (mol cat)?1 h?1 was observed using the latter nickel complex as catalyst, activated by methylaluminoxane. The norbornene polymers thus obtained are of high molecular weight but with rather low polydispersity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
104.
Elisabeth Kallin Hans Lönn Thomas Norberg Mikael Elofsson 《Journal of carbohydrate chemistry》2013,32(4):597-611
Abstract Reducing oligosaccharides were converted in good yields into the corresponding primary glycosylamines by treatment with aqueous ammonium bicarbonate. The glycosylamines were then acryloylated and the obtained oligosaccharide N-acryloyl glycosylamines were copolymerized with acrylamide. High molecular weight, linear copolymers were obtained, which were useful as antigens in immunoassays. 相似文献
105.
Herein, the iron‐catalyzed reduction of a variety of alkynes with silanes as a reductant has been examined. With a straightforward catalyst system composed of diiron nonacarbonyl and tributyl phosphane, excellent yields and chemoselectivities (>99 %) were obtained for the formation of the corresponding alkenes. After studying the reaction conditions, and the scope and limitations of the reaction, several attempts were undertaken to shed light on the reaction mechanism. 相似文献
106.
107.
108.
109.
Elisabeth Kapatsina 《Nachrichten aus der Chemie》2016,64(10):1022-1022
110.
Thomas Heuser Elisabeth Weyandt Dr. Andreas Walther 《Angewandte Chemie (International ed. in English)》2015,54(45):13258-13262
Switchable self‐assemblies respond to external stimuli with a transition between near‐equilibrium states. Although being a key to present‐day advanced materials, these systems respond rather passively, and do not display autonomous dynamics. For autonomous behavior, approaches must be found to orchestrate the time domain of self‐assemblies, which would lead to new generations of dynamic and self‐regulating materials. Herein, we demonstrate catalytic control of the time domain of pH‐responsive peptide hydrogelators in a closed system. We program transient acidic pH states by combining a fast acidic activator with the slow, enzymatic, feedback‐driven generation of a base (dormant deactivator). This transient state can be programmed over orders of magnitude in time. It is coupled to dipeptides to create autonomously self‐regulating, dynamic gels with programmed lifetimes, which are used for fluidic guidance, burst release, and self‐erasing rapid prototyping. 相似文献