全文获取类型
收费全文 | 476篇 |
免费 | 6篇 |
国内免费 | 4篇 |
专业分类
化学 | 333篇 |
晶体学 | 13篇 |
力学 | 10篇 |
数学 | 20篇 |
物理学 | 110篇 |
出版年
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2016年 | 3篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 25篇 |
2012年 | 33篇 |
2011年 | 29篇 |
2010年 | 27篇 |
2009年 | 18篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 20篇 |
2005年 | 34篇 |
2004年 | 22篇 |
2003年 | 22篇 |
2002年 | 29篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 10篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有486条查询结果,搜索用时 0 毫秒
61.
Katsuya Ishiguro Kohtaro Tomizawa Yasuhiko Sawaki Hiizu Iwamura 《Tetrahedron letters》1985,26(31):3723-3726
A tracer study for the rearrangement of carbonyl oxides to esters using doubly-labeled oxygen lead to a conclusion that carbonyl oxides do not isomerize directly to dioxyranes and the rearrangement to esters proceeds via a cyclic tetroxide. 相似文献
62.
The basic characteristics of vaporization and flowing behavior of n-pentane injected through a single nozzle into a column of hot water have been studied photographically. Subcools at the nozzle-outlet have a strong influence on the critical temperature driving forces at over which vaporization can be maintained. The length of a Rayleigh jet is remarkably shortened when vaporization occurs, whereas mean diameters of drops are little affected whether vaporization occurs or not. A specific condition that a bubble appears in each drop is satisfied not on a specific line but over a wide region on the ΔT∞ - UN plane. 相似文献
63.
64.
65.
Yozo Chatani Takao Ohno Tadafumi Yamauchi Yasuhiko Miyake 《Journal of Polymer Science.Polymer Physics》1973,11(2):369-388
One of the cyclic oligomers of formaldehyde, 1,3,5,7,9,11-hexoxecane, was found to undergo polymerization in the solid state to form polyoxymethylene both during and subsequent to x- or γ-irradiation. The polymer yield increases with polymerization temperature but decreases drastically near the melting point of the hexoxecane crystal. In order to clarify the specificity of the solid-state polymerization, the crystal structure of hexoxecane was first analyzed; hexoxecane forms a trigonal crystal with cell dimensions of a = b = 7.917 Å, c = 11.345 Å, space group R3 –C3i2, three molecules of 3 symmetry per unit cell. The polyoxymethylene as polymerized from a single crystal of hexoxecane is highly crystalline and the crystallites are definitely oriented with respect to the original crystal. There are three kinds of oriented trigonal polyoxymethylene: i.e., with the polymer chains oriented along the 〈100〉, 〈001〉, and 〈210〉 axes of the hexoxecane crystal. The relative yields of these crystallites depend upon the polymerization temperature. In addition to the ordinary trigonal polyoxymethylene, oriented orthorhombic polyoxymethylene was also found in the case of polymerization during treatment with x-rays. 相似文献
66.
67.
In the dimethyl sulfoxide (DMSO)-metal oxide oxidation of alcohol to carbonyl compound, molybdenum oxides were the only useful catalytic reagents, and various alcohols were oxidized to the corresponding carbonyl compounds in high yields. 相似文献
68.
Yumiko Sano Keishi Kato Masaaki Yokoyama Yasuhiko Shirota Hiroshi Mikawa 《Molecular Crystals and Liquid Crystals》2013,570(1-2):137-141
Glass-forming properties of 2-pyrazoline derivatives were examined and discussed in terms of the molecular structure. The results show that the molecular shape of 1,3,5-triaryl-2-pyrazolines is responsible for the glass-forming properties of these compounds. Glass transition points of several 1,3,5-triaryl-2-pyrazoline derivatives were measured. 相似文献
69.
Yuzuru Katagiri Kenzo Kanohta Kazuhiko Nagasawa Tadao Okusa Toshio Sakai Osamu Tsumura Yasuhiko Yotsui 《Analytica chimica acta》1981,133(4):535-543
A practical search system for proton n.m.r. spectra is reported. The coding rules and search algorithms are described in detail. Data for 8000 spectra have been converted into a computer-readable file from printed charts. Several search tests are used to evaluate the usefulness of the search system, and various effects of experimental conditions such as different instruments, frequencies and solvents on recall efficiency are described. The results presented indicate that the system should be applicable to routine analytical work. 相似文献
70.
Yoshikatsu Miyashita Yoshimasa Takahashi Yasuhiko Yotsui Hidetsugu Abe Shin-Ichi Sasaki 《Analytica chimica acta》1981,133(4):615-624
A graph-theoretical algorithm based on the minimal spanning tree (MST) is applied to structure—activity problems. The method is helpful in interpreting the results of cluster analysis, and becomes useful by combining with the mapping method that illustrates approximations of a multidimensional data structure. The antibacterial spectra of cephalosporins are analyzed by the MST approach and a linear mapping method. The main diameter obtained by MST gives the representative data set and clarifies the substituent effect on the antibacterial spectra. Relations between the central nervous system activity of benzodiazepine derivatives and their physicochemical parameters are also analyzed by MST and nonlinear mapping methods. These results for cephalosporins and benzodiazepines prove that MST is very useful in understanding the position of compounds in feature space and their activities. 相似文献