全文获取类型
收费全文 | 769篇 |
免费 | 58篇 |
专业分类
化学 | 616篇 |
晶体学 | 8篇 |
力学 | 4篇 |
数学 | 56篇 |
物理学 | 143篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 9篇 |
2020年 | 20篇 |
2019年 | 24篇 |
2018年 | 13篇 |
2017年 | 6篇 |
2016年 | 37篇 |
2015年 | 28篇 |
2014年 | 23篇 |
2013年 | 33篇 |
2012年 | 47篇 |
2011年 | 58篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 61篇 |
2007年 | 41篇 |
2006年 | 42篇 |
2005年 | 50篇 |
2004年 | 28篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 18篇 |
2000年 | 15篇 |
1999年 | 6篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有827条查询结果,搜索用时 12 毫秒
61.
Hoshino K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(13):2727-2731
The present article focuses on a recent finding concerning dinitrogen fixation by using titanium oxide/conducting polymer composite systems and its comparison with an earlier fixation method (Schrauzer process) that makes use of a powdered titanium oxide. Both processes work under the stimulus of light at room temperature and pressure, but dinitrogen is fixed to a solid ammonium salt crystal in the former and to a gaseous ammonia molecule in the latter process. Differences in the physicochemical concepts between the two processes are discussed. 相似文献
62.
Mitsuo Hoshino 《Journal of Pure and Applied Algebra》2003,177(2):159-175
Let A be an artin algebra and e∈A an idempotent with add(eAA)=add(D(AAe)). Then a projective resolution of AeeAe gives rise to tilting complexes for A, where P(l)• is of term length l+1. In particular, if A is self-injective, then is self-injective and has the same Nakayama permutation as A. In case A is a finite dimensional algebra over a field and eAe is a Nakayama algebra, a projective resolution of eAe over the enveloping algebra of eAe gives rise to two-sided tilting complexes {T(2l)•}l?1 for A, where T(2l)• is of term length 2l+1. In particular, if eAe is of Loewy length two, then we get tilting complexes {T(l)•}l?1 for A, where T(l)• is of term length l+1. 相似文献
63.
Rapid large-scale magnetic-field dissipation is observed in a full kinetic simulation of cross-field current instabilities in a current sheet even when the thickness of the current sheet is at ion scale. The Kelvin-Helmholtz instability caused by the velocity shear between the current-carrying ions and the cold background ions excites the lower-hybrid drift instability at the edges of the undulated current sheet. We show that the nonlinear coupling between these two instabilities is responsible for the observed rapid dissipation. The simulation result presents a new route for magnetic-field dissipation in an ion-scale current sheet and demonstrates the general significance of nonlinear cross-scale coupling in collisionless plasmas. 相似文献
64.
65.
M Yoshikawa H Endo K Hoshino Y Sugawara O Takaiti S Kanda K Imai 《Biomedical chromatography : BMC》1990,4(5):181-187
A new method for the high performance liquid chromatographic (HPLC) determination of N-(N-acetyl-L-methionyl)-O,O-bis(ethoxycarbonyl)dopamine (TA-870), a dopamine prodrug, in biological fluid has been developed. In order to measure with an electrochemical detector (ECD), TA-870 was passed first through an immobilized carboxylesterase column to be converted to the electrochemically active deethoxycarbonylated TA-870 (DEC-TA-870). The properties of this carboxylesterase immobilized on Sepharose 4B were examined by this flow injection system. Hydrolysis of TA-870 with this immobilized carboxylesterase was a maximum at pH 7-8 and 50 degrees C, and the activity decreased in the presence of organic solvent such as acetonitrile. For the determination of TA-870 in biological fluids, an HPLC-immobilized enzyme-ECD system using a column-switching technique was developed. The blood was deproteinized with ethanol, and TA-870 in the ethanol extracts was adsorbed in Bond Elut C18. The dichloromethane eluate from Bond Elut C18 was injected into the HPLC system. The HPLC apparatus was composed of three pumps, two separation columns (LiChrosorb Si 60 and mu Bondasphere), a trap column (Bond Elut), an enzyme column, ECD and the column-switching system. The calibration curve for TA-870 in blood was linear in the range from 2 to 200 ng/mL. This new assay method might be useful also for the determination of other catechol ester compounds. 相似文献
66.
67.
Kotaro Nagatani Yunosuke Hoshino Haruka Tezuka Masahisa Nakada 《Tetrahedron letters》2017,58(10):959-962
A synthetic pathway to the C-ring fragment of cotylenin A which emerged from our retrosynthetic analysis of cotylenin A is described. The catalytic asymmetric intramolecular cyclopropanation (CAIMCP) of the α-diazo-β-keto ester bearing 2,4,6-trimethylphenyl group as the ester part has been found to afford the crystalline product with high ee, which allowed to establish the approach to the C-ring fragment which required ten-pot operations. The developed approach would be beneficial to a large scale synthesis of the C-ring fragment for the total synthesis of cotylenin A. 相似文献
68.
A new effective copper catalyzed CO coupling reaction using excess amount of strongly coordinating monodentate ligands was successfully developed. Among the DMAP-type monodentate ligands, 4-pyrrolidinopyridine afforded the best results. The developed reaction is widely applicable for the synthesis of various hindered or acyclic secondary alkyl-aryl ethers. In this study, a novel and remarkable acceleration of the coupling reaction using excess amount of monodentate ligands was discovered. 相似文献
69.
Makoto Mouri Taiji Ikawa Mamiko Narita Fumihiko Hoshino Osamu Watanabe 《Macromolecular bioscience》2010,10(6):612-620
In our photo‐induced immobilization technique for an antibody (IgG) using azopolymers, the introduction of COOH and NMe2 into the azopolymers, which can introduce surface charges, strongly affected the immobilization properties such as the efficiency of immobilization and the activity of the immobilized IgG (i.e., the orientation of the immobilized IgG). The introduction of COOH promoted a more active orientation of the immobilized IgG. The orientation was determined during the adsorption process onto the azopolymer surface in solution before photo‐immobilization, and was maintained during the photo‐immobilization. The surface charge of the azopolymer appears to be an important factor for IgG orientation, which involves electrostatic interactions between its Fab and the azopolymer surface.
70.
Laurean Ilies Dr. Yoshiharu Sato Dr. Chikahiko Mitsui Hayato Tsuji Dr. Eiichi Nakamura Prof. Dr. 《化学:亚洲杂志》2010,5(6):1376-1381
A diversity‐oriented synthetic strategy allowed us to design a series of conjugated molecules containing multiple benzosilole units that can be utilized as efficient hole‐blocking materials for phosphorescent organic light emitting diodes (OLEDs). Some of these compounds showed a performance surpassing that of the current standard, bathocuproine. The new compounds were easily synthesized in a modular fashion from a previously reported 3‐stannyl benzosilole building unit. Studies on the properties of these compounds in solution and in the solid state indicate that they possess high electron affinity, high ionization potential, and form stable amorphous films that show high electron‐drift mobility. The correlation between their molecular properties and the efficiency of the OLED device performance is also investigated. 相似文献