全文获取类型
收费全文 | 335篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 146篇 |
晶体学 | 3篇 |
力学 | 12篇 |
数学 | 21篇 |
物理学 | 163篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 14篇 |
2013年 | 26篇 |
2012年 | 13篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 17篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 1篇 |
2002年 | 6篇 |
2001年 | 2篇 |
1998年 | 6篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 15 毫秒
261.
262.
263.
264.
This report describes a Ronchi-grating shearing interferometric collimation method for determining the refractive index of a lens. A new formula has been deduced for the refractive index of the lens, which is independent of lens parameters. This newly developed device has two lenses. One of them collimates the light from a point source while the other acts as a decollimator. The point source acting as a test target is situated in the front focal plane of the collimator. The test lens is placed inside a glass cell in the back focal plane of the collimator. The Ronchi grating is exactly placed in the back focal plane of the decollimator, and a fringe-free space is observed in the common region. When the test lens is immersed in a liquid cell, it disturbs the focal point and hence interference fringes are observed. The combined system consisting of the test lens and the decollimator is moved to bring the focal point on the Ronchi grating. Thus, the difference between the two settings gives the amount of defocusing. 相似文献
265.
266.
267.
A new synthesis of fluorinated 4H-1,4-benzothiazines is being reported for the first time, obtained by condensing O-aminobenzenethiol with fluorinated β-diketones. An oxidative cyclisation mechanism, involving an intramolecular nucleophilic attack in an intermediate enamine system is suggested. 相似文献
268.
Soni Bhupendra K. Paterek J. Robert Pradhan Salil Srivastava Vlpul J. 《Applied biochemistry and biotechnology》1998,(1):709-718
Oil-gas exploration and production (E&P) soils contaminated with total petroleum hydrocarbons (TPHs) have been tested for
degradation by two different treatments: biological and chemical. Biological treatment includes the use of native microorganisms
for transformation of the various hydrocarbons found in E&P soils. Degradation of TPH of 80 and 86%, was achieved for two
different soils, respectively in control experiments. The effect of growth stimulants such as glucose, acetic acid, and valeric
acid was examined on TPH degradation. Incorporation of inducer (valerate) enhanced the degradation up to 89 and 93%, for the
two soils, respectively. A large portion (> 41%) of contaminant in one soil was comprised of compounds in the carbon range
of C10-C16 and < 7% constituted carbon range of C24-C28. The degradation of C10-C16 compounds was higher (> 98%) as compared to C24-C28 compounds (< 75%). Likewise, the degradation rate was also higher (58 mg/kg/d) for lower compounds as compared to higher
carbon range compounds (6.7 mg/kg/d). Experiments conducted on chemical treatment included the effect of chelators on stabilization
of H2O2, comparative studies between buffer and water (used for soil preparation), and the effect of pH on TPH degradation. The rate
of oxygen evolution from H2O2 was significantly reduced with use of either chelated iron or phosphate buffer using naphthelene as a model compound. Chemical
treatment demonstrated a higher degradation of TPH from contaminated soils at pH 4.0 as compared to a pH of 7.0. More degradation
was obtained with slurry prepared in phosphate buffer as compared to deionized water. 相似文献
269.
270.