全文获取类型
收费全文 | 672篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
化学 | 490篇 |
晶体学 | 5篇 |
力学 | 35篇 |
数学 | 57篇 |
物理学 | 103篇 |
出版年
2020年 | 7篇 |
2019年 | 6篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 34篇 |
2011年 | 36篇 |
2010年 | 19篇 |
2009年 | 22篇 |
2008年 | 44篇 |
2007年 | 47篇 |
2006年 | 40篇 |
2005年 | 29篇 |
2004年 | 32篇 |
2003年 | 19篇 |
2002年 | 31篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 14篇 |
1984年 | 19篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1964年 | 2篇 |
排序方式: 共有690条查询结果,搜索用时 15 毫秒
1.
Oscillation is found in many biological systems, and among them the enzymatic oscillatory reaction has been well studied using an enzyme solution. We show in this study for the first time that oscillation occurs when catalase is immobilized to controlled pore glass (CPG). The oscillatory wave mode changes with the distance among the CPG, electrode, or dialysis membrane. The lower substrate concentration results in oscillation with a longer period. This tendency agrees with a previous study using an enzyme solution. Furthermore, we show that the oscillation occurs when no dialysis membrane is used. These results show the wider applicability of the system to analysis or novel device fabrication. 相似文献
2.
Yoshikazu Takada 《Annals of the Institute of Statistical Mathematics》1998,50(2):325-335
This paper gives a condition which implies the nonexistence of parametric statistical procedures with bounded risk or error performance characteristics. Many examples for which such a condition is satisfied are considered. 相似文献
3.
The engineering of many modern electronic devices demands control over a crystal down to the thickness of a single layer of atoms—and future demands will be even more challenging. Such control is achieved by the method of crystal growth known as epitaxy, and that makes this method the subject of intense study. More than that, recent advances are revolutionizing our knowledge of how surfaces grow. In fact, growing surfaces show a beautifully rich variety of phenomena, many of which are only now beginning to be uncovered. In the past few years many surface imaging techniques have been used to give us a close look at how crystals grow—while they are growing. The purpose of this article will be to illustrate some of the ways real surfaces grow and change as revealed by some of the latest in situ microscopic imaging technologies.
It is often said that crystal growth is more of an art than a science. Here we will show that it is emphatically both. 相似文献
4.
5.
B. Hausnerova N. Honkova A. Lengalova T. Kitano P. Saha 《Polymer Science Series A》2006,48(9):951-960
The processing of fiber-reinforced thermoplastics is often accompanied by a significant fiber fracture. Therefore, it is important
to assess the effect of processing variables on the extent of fiber damage occurring during product fabrication, such as extrusion
or injection molding. The present paper discusses fiber damage caused by shear forces exerted on the composite by a molten
matrix in both experimental and theoretical terms. The degradation process in carbon fiber-polypropylene composites is studied
in a broad range of shear rates, although it occurs significantly only under high shearing in a capillary. Changes in fiber
length and its distribution during the multi-flow through a capillary, as well as the materials’ rheological properties found
in research after shearing, are discussed and the results are compared with a model of fiber-length analysis for the mixing-regrinding
process.
Published in Russian in Vysokomolekulyamye Soedineniya, Ser. A, 2006, Vol. 48, No. 9, pp. 1628–1639.
The text was submitted by the authors in English. 相似文献
6.
Masahiro Nakao Chikako Yamazaki Hiroshi Tominaga Takako Yamaguchi Yoshikazu Fujita 《Analytical sciences》2006,22(2):313-316
A simple and highly sensitive spectrophotometric method for the determination of anthracycline anticancer agents, such as Daunorubicin hydrochloride (DAU), was established by using aluminum(III) and Chromazurol S (CAS) in a nonionic surfactant micellar medium. In the case of determination of DAU, the apparent molar absorptivity was 1.3 x 10(5) dm3 mol(-1) cm(-1) at 615 nm. Beer's law was obeyed in the concentration range of 0.028 - 2.82 microg ml(-1) for DAU. Owing to no need for solvent extraction, this method could be applied to assays of DAU and related drugs in pharmaceutical preparations. 相似文献
7.
8.
9.
10.
(+)-Biotin (1) was synthesized in 25% overall yield over 11 steps from L-cysteine. The contiguous asymmetric centers at C-3a and C-6a were formed through a novel and highly stereoselective Lewis base-catalyzed cyanosilylation of alpha-amino aldehyde 3 to provide anti-O-TMS-cyanohydrin 4 with high stereoselectivity and in high yield (anti/syn = 92:8, 96%). Treatment of 4 with a di-Grignard reagent, 1,4-bis(bromomagnesio)butane, followed by carbon dioxide, efficiently installed the 4-carboxybutyl chain at C-4 to give keto acid 5. The final cyclization to bicyclic compound 7b, a precursor to 1, was realized by a palladium-catalyzed intramolecular allylic amination of cis-allylic carbonate 6b that was elaborated from 5. 相似文献