全文获取类型
收费全文 | 833篇 |
免费 | 26篇 |
国内免费 | 8篇 |
专业分类
化学 | 654篇 |
晶体学 | 16篇 |
力学 | 15篇 |
数学 | 51篇 |
物理学 | 131篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 20篇 |
2015年 | 23篇 |
2014年 | 15篇 |
2013年 | 44篇 |
2012年 | 28篇 |
2011年 | 47篇 |
2010年 | 24篇 |
2009年 | 40篇 |
2008年 | 48篇 |
2007年 | 51篇 |
2006年 | 56篇 |
2005年 | 43篇 |
2004年 | 52篇 |
2003年 | 35篇 |
2002年 | 44篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 11篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 7篇 |
1972年 | 6篇 |
排序方式: 共有867条查询结果,搜索用时 0 毫秒
751.
752.
Hiroshi Fujimoto Nobuaki Koga Masayuki Endo Kenichi Fukui 《Tetrahedron letters》1981,22(35):3427-3430
A pair of orbital transformations Is suggested to provide a simple criterion to interpret the pathway of nonpolar reactions and to elucidate the reactive domains for competitive reactions. 相似文献
753.
754.
755.
756.
Noritaka Miyoshi Tetsuya Yamamoto Nobuaki Kambe Shinji Murai Noboru Sonoda 《Tetrahedron letters》1982,23(46):4813-4816
Treatment of ketones or aldehydes with selenium dioxide and diphenyl diselenide in the presence of acid catalyst afforded the corresponding α-phenylselenenyl carbonyl compounds in good yields. 相似文献
757.
Satoru Toyooka Nobuaki Hayasaka Munehide Kataguchi Fumio Kobayashi 《Optical Review》1998,5(4):207-211
A spectral intensity distribution of interference colors which is a function of optical path difference (OPD) is represented as a pattern vector on a subspace. A new algorithm to design a color scale on the subspace to estimate OPD values is proposed. In experiments, interference colors generated by a differential interference microscope (DIM) were examined. A subspace spanned by four orthogonal bases was constructed to make a color scale to determine OPD values in the range between 0 nm and 1000 nm. Estimated OPD values almost coincided with these expected. In an experiment on two-dimensional interference colors obtained by a spherical surface of a ballbearing observed by DIM, the resultant OPD distribution coincided well with that expected within a standard deviation of 12.8 nm. 相似文献
758.
This paper presents a kernel smoothing method for multinomial regression. A class of estimators of the regression functions is constructed by minimizing a localized power-divergence measure. These estimators include the bandwidth and a single parameter originating in the power-divergence measure as smoothing parameters. An asymptotic theory for the estimators is developed and the bias-adjusted estimators are obtained. A data-based algorithm for selecting the smoothing parameters is also proposed. Simulation results reveal that the proposed algorithm works efficiently. 相似文献
759.
Takayuki Iseki Takashi Shigematsu Mikio Okumura Takashi Sugawara Minoru K. Kurosawa 《Optical Review》2006,13(4):195-200
We have developed a two-dimensionally deflecting mirror actuating system with a deflection angle of 20°, which takes full
advantage of the characteristics of a two-dimensional surface acoustic wave (SAW) motor. A magnetic slider moves with frictional
drive by the Rayleigh mode of the SAW and deflects the mirror by the force of magnetic attraction. For the actuation of a
20° deflection angle, only a 10 ms duration of driving voltage is required owing to the high-speed characteristic of the motor,
followed by an additional 10 ms for damping of the mirror structure produced in order to complete holding of the angle. No
power supply is necessary to hold the angle. Furthermore, the resolution of the angle is 0.0015° because of the high-resolution
capability of the motor. The mirror deflection system showed a 104 dynamic range of angle positioning ability. 相似文献
760.
Wakichi Fukuda Masahiro Nakao Kinichi Okumura Hiroshi Kakiuchi 《Journal of polymer science. Part A, Polymer chemistry》1972,10(1):237-250
Both vinyl methacrylate (VMA) and vinyl acrylate (VA) were homopolymerized by n-butyllithium catalyst at ?78°C. Both of the anionic polymers were soluble in common organic solvents, and only vinyl group was contained in the polymers. Both of the monomers were homopolymerized by free-radical catalysts under different conditions. The soluble polymers were obtained under low monomer concentrations and at low conversions. It was estimated by NMR and infrared spectroscopy that both the soluble polymers contained mainly a vinyl group, similar to the anionic polymers. The soluble VMA polymers comprised 10–20% cyclic units for monomer concentrations ranging from 1.8 to 0.5 mole/I. The soluble VA polymers comprised 50–60% cyclic units for monomer concentrations ranging from 0.9 to 0.3 mole/l. It was suggested that the cyclic units did not consist of γ-lactone but of larger-membered rings than δ-lactone or of ladder structural units. The difference between the cyclization content of poly-VMA and that of poly-VA might be explained by the copolymerization data of the reference monomers. 相似文献