全文获取类型
收费全文 | 323篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
化学 | 201篇 |
力学 | 8篇 |
数学 | 38篇 |
物理学 | 84篇 |
出版年
2019年 | 3篇 |
2018年 | 2篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 49篇 |
2012年 | 3篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 16篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 9篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 6篇 |
1968年 | 5篇 |
1961年 | 4篇 |
1933年 | 2篇 |
1927年 | 2篇 |
排序方式: 共有331条查询结果,搜索用时 31 毫秒
231.
232.
G.W. SWENSON JR 《Journal of sound and vibration》2002,255(3):519-529
A directional microphone system for field recording of sounds in the air often involves a parabolic reflector to focus the sound waves on the microphone (transducer) element. Some deficiencies of such a system are noted with respect to reproduction of spectra. The reflector system, involving as it does a structure comparable to a wavelength in linear dimension, is not susceptible to traditional high- or low-frequency approximate methods of computation. Modern numerical techniques now permit precise calculation of the directional responses of small reflectors of various shapes. One result is a proposal for a very economical and effective system involving a plane reflector. Other baffle shapes are also investigated, which may be of interest in special applications. 相似文献
233.
H. Charles Manning Mingfeng Bai Rafal Lisiak Darryl J. Bornhop 《Tetrahedron letters》2005,46(28):4707-4710
Phosphonic acid appended tetraazacyclododecane (cyclen)-based macrocycles are attractive metal-ion chelators for diagnostic imaging and therapeutic delivery. Here, we report a novel P-protected methodology that facilitates the rapid synthesis and purification of targeted phosphonic acid bearing macrocycles. Purification of these intermediates is facile, and deprotection using neat TFA is rapid, yet mild enough to preserve the integrity of delicate peptides and/or targeting moieties. 相似文献
234.
H Pledger JR. G.-S. Wu T. S. Young T. E. Hogen-esch G. B. Butler 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1297-1307
Graft copolymers of acrylamide and yellow dextrin were prepared using cerium(IV) as initiator. The yellow dextrin had a very broad molecular weight distribution but was fractionated utilizing dialysis and ultrafiltration membranes. Initiator efficiencies were determined using size exclusion chromatography and were found to be between 2.4 and 34%. Initiator efficiency increased with acrylamide concentration at constant cerium (IV) and yellow dextrin concentrations, and decreased with increasing cerium(IV) concentration at constant acrylamide and yellow dextrin concentrations. Plots of acrylamide conversion and intrinsic viscosity vs initial acrylamide concentration at constant yellow dextrin and ceric ion concentrations showed a maximum at about 2.0 M. 相似文献
235.
We report dramatically improved total syntheses of two highly selective V600EBRAF inhibitors, PLX4720 and PLX4032, that leverages microwave-assisted organic synthesis (MAOS). Compared with previously reported approaches, our novel MAOS method significantly reduces overall reaction time without compromising yield. In addition to providing a gram-scale route to these compounds for preclinical oncology research, we anticipate this approach could accelerate the synthesis of azaindoles in high-throughput, library-based formats. 相似文献
236.
Ohne Zusammenfassung 相似文献
237.
B. Brukner W. Overbeck J. Duclaux J. Errera H. Bechhold L. Gutlohn H. W. Morse G. W. Pierce V. Szidon E. Fouard und J. Manning 《Fresenius' Journal of Analytical Chemistry》1927,71(10):394-398
Ohne Zusammenfassung 相似文献
238.
Anthony Manning 《Proceedings Mathematical Sciences》1995,105(3):269-271
A givenn ×n matrix of rational numbers acts onC
π and onQ
π. We assume that its characteristic polynomial is irreducible and compare a basis of eigenvectors forC
π with the standard basis forQ
π. Subject to a hypothesis on the Galois group we prove that vectors from these two bases are as independent of each other
as possible. 相似文献
239.
240.