全文获取类型
收费全文 | 967篇 |
免费 | 15篇 |
国内免费 | 2篇 |
专业分类
化学 | 547篇 |
晶体学 | 15篇 |
力学 | 11篇 |
数学 | 92篇 |
物理学 | 319篇 |
出版年
2021年 | 9篇 |
2019年 | 8篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 6篇 |
2013年 | 76篇 |
2012年 | 36篇 |
2011年 | 34篇 |
2010年 | 25篇 |
2009年 | 15篇 |
2008年 | 30篇 |
2007年 | 45篇 |
2006年 | 45篇 |
2005年 | 41篇 |
2004年 | 27篇 |
2003年 | 28篇 |
2002年 | 25篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 17篇 |
1998年 | 8篇 |
1997年 | 17篇 |
1996年 | 26篇 |
1995年 | 20篇 |
1994年 | 27篇 |
1993年 | 23篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 20篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 9篇 |
1976年 | 17篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1972年 | 6篇 |
1970年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有984条查询结果,搜索用时 31 毫秒
121.
122.
H. L. Seifert J. M. Wouters D. J. Vieira H. Wollnik X. G. Zhou X. L. Tu Z. Y. Zhou G. W. Butler 《Zeitschrift für Physik A Hadrons and Nuclei》1994,349(1):25-32
The ground state masses of thirty-nine neutronrich nuclei from51Ca to72Ni have been measured using the Time-of-Flight Isochronous (TOFI) spectrometer. Eight of these masses have been measured for the first time and thirty-one are remeasurements of neutron-rich nuclei previously reported. Good agreement between these results and a previous TOFI experiment was observed except for the most neutron-rich isotopes of vanadium through iron with the present results being more bound and in better agreement with theory. The low binding energy of68Ni, as indicated by an unreasonably low two-neutron separation energy, suggests the presence of a high-lying, long-lived isomeric state in this nucleus. 相似文献
123.
124.
125.
A novel low temperature technique has been developed for the synthesis of celsian glass-ceramics. The technique involves ion exchange of zeolites, their subsequent heat treatment to form a glassy phase from which celsian is crystallized. Monoclinic celsian was produced at temperatures as low as 1000°C at heat treatment times of 6 h. 相似文献
126.
The structure of diaquo(1,2-dimethoxyethane)lithium tetraphenylborate, [Li(CH3OCH2-CH2OCH3)(H2O)2][BPh4], has been determined at 293 K. The compound crystallizes in the trigonal P3(1)21 space group (a = b = 9.9760(14), c = 23.662(5)). Both the lithium and the boron sit on a twofold rotation axis. The lithium is coordinated to two water oxygens and both ether oxygens of the 1,2-dimethoxyethane group. The coordination geometry is significantly distorted from a tetrahedron by the twisting of the plane containing the two water oxygens and the lithium relative to that containing the two 1,2-dimethoxyethane oxygens and the lithium. The five-membered chelate ring formed by chelation of the 1,2-dimethoxyethane to the lithium is a twist envelope consistent with the twofold rotation axis passing through the lithium and the center of the carbon–carbon bond of the 1,2-dimethoxyethane. Hydrogen bonding between each water hydrogen and a phenyl group of the tetraphenylborate is observed and results in a linear polymeric structure. 相似文献
127.
Reinhardt J. Heuer Robert Thayer Sataloff Kate Emerich Rhonda Rulnick Margaret Baroody Joseph R. Spiegel Gursel Durson John Butler 《Journal of voice》1997,11(1):88-94
This preliminary retrospective study of 19 female patients and 22male patients with unilateral recurrent nerve lesions demonstrated the promise of objective measurements in predicting the need for surgery, the efficacy of voice therapy in ameliorating vocal symptoms, and the effects of therapy in conjunction with surgery. Sixty-eight percent (68%) of the female patients and 64% of the male patients did not elect to have surgery. Outcome satisfaction of nonsurgical and surgical patients appeared to be similar. The data from this study support the importance of preoperative therapy for patients with unilateral vocal fold paralysis. 相似文献
128.
M. A. Butler 《Fiber and Integrated Optics》1989,8(3):193-202
A method is proposed for using optical fiber interferometers to detect single energy impulses of very short time duration. The interferometer is used to measure the periodic strains induced in a mass that is shock-excited into mechanical oscillation by an energy impulse. This technique is demonstrated using an optical fiber ring resonator to measure the energy content of current pulses with durations in the microsecond range. 相似文献
129.
A route to meta-benzenocyclophanes containing four tetrazole rings in the macrocycle is described. 相似文献
130.
The kibdelones are aromatic polyketide natural products featuring isoquinolinone and tetrahydroxanthone ring systems. They display potent cytotoxicity toward a range of human cancer cell lines. Here, we present an enantioselective total synthesis of kibdelone C that utilizes a Shi epoxidation to establish the absolute and relative stereochemistry, an acid-catalyzed cyclization to form the tetrahydroxanthone, and a C-H arylation to complete the hexacyclic skeleton. 相似文献