全文获取类型
收费全文 | 416篇 |
免费 | 10篇 |
专业分类
化学 | 231篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 15篇 |
物理学 | 175篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 20篇 |
2012年 | 22篇 |
2011年 | 17篇 |
2010年 | 6篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 25篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1972年 | 4篇 |
排序方式: 共有426条查询结果,搜索用时 15 毫秒
131.
The effect of aberrations of an optical system on gaussian beams is analyzed. If an incident position of the beams of the optical system does not coincide with the center of its pupil, the beams suffer from aberrations differently in accordance with the various incident positions. The Strehl definition of the beams is studied as a function of the incident position of the beams and the kind of abberations present in the optical system. 相似文献
132.
The general formula derived in a previous paper is applied to obtain the intensity distribution along the axis normal to a slit aperture in the Fresnel diffraction field when the spatial mutual coherence function of the illumination over the aperture takes three different forms of correlation. It is shown that the axial intensity distribution of Fresnel diffraction by the slit aperture is effectively influenced by the coherence condition across the diffracting aperture. 相似文献
133.
Apodization problems in coherent imagery of removing the edge ringing effect are proposed by considering the edge shifting phenomenon and the passivity of the optical imaging system and are solved by means of the calculus of variations. The resultant pupil functions and corresponding edge image intensity distributions are presented and discussed. 相似文献
134.
Shinzi Kato Toshimitsu Kato Takashi Yamauchi Yutaka Shibahashi Etsuo Kakuda Masateru Mizuta Yoshio Ishii 《Journal of organometallic chemistry》1974,76(2):215-224
Some crystalline di- and tri-phenylstannyl esters [ArCS2SnPh3 and (ArCS2)2SnPh2] of aromatic dithio acids have been prepared in good yields and characterized. Preferential cleavage of the SnS bond of the ester was observed by treating them with primary and secondary amines as well as with phenacylidenetetramethylenesulfurane. 相似文献
135.
136.
The relation between the velocity of a moving diffuse object and the mean number of integrated speckles in the certain time interval at the far-field plane of the object is obtained. By using this relation based on the first order statistics of integrated speckles, a new method of measuring the velocity of the diffuse object is proposed and experimentally verified. The first order probability density function of time-integrated speckles is also studied from which the validity of the present method is verified. 相似文献
137.
Junji Ohtsubo Toshimitsu Asakura 《Applied Physics A: Materials Science & Processing》1977,14(2):183-187
The probability density function and average contrast of the sum of two speckle patterns produced with various intensity ratios
and correlation conditions have been experimentally investigated. The experimental results are compared with the theoretical
ones obtained by Barakat and Goodman. Comparison shows excellent agreement between the experimental and theoretical results. 相似文献
138.
Hayashi K Rahman SM Ohno H Tanaka T Toyooka N Nemoto H Hayashi T 《Chemical & pharmaceutical bulletin》2004,52(8):1015-1017
Herpes simplex virus type 1 thymidine kinase (HSV TK) is involved in both antiherpetic therapy and cancer gene therapy with acyclovir (ACV) and ganciclovir (GCV). Enhanced sensitivity to these drugs is advantageous in their clinical use. In the present study, scopadulciol (SDC) and its related compounds were evaluated for their stimulatory effect on the cytotoxicity of ACV and GCV by determination of selective toxicities against HSV TK-expressing HeLa cells. Although SDC remarkably potenciated the cytotoxicity of ACV and GCV, the other tested compounds showed only weak selectivity, except for compound 34. 相似文献
139.