全文获取类型
收费全文 | 403篇 |
免费 | 10篇 |
国内免费 | 4篇 |
专业分类
化学 | 348篇 |
晶体学 | 6篇 |
力学 | 7篇 |
数学 | 7篇 |
物理学 | 49篇 |
出版年
2019年 | 4篇 |
2018年 | 2篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 23篇 |
2012年 | 20篇 |
2011年 | 26篇 |
2010年 | 17篇 |
2009年 | 12篇 |
2008年 | 25篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 22篇 |
2004年 | 23篇 |
2003年 | 10篇 |
2002年 | 16篇 |
2001年 | 7篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 12篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1967年 | 3篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有417条查询结果,搜索用时 15 毫秒
121.
122.
Keiichi Tanaka Koichi Yamada Toru Nakagawa Kozo Kuchitsu John Overend 《Journal of Molecular Spectroscopy》1975,54(2):243-260
A high-resolution infrared spectrum of H2CO was measured in the range from 2600 to 3300 cm?1. Vibration-rotation lines assigned to the combination bands ν2 + ν3 (a-type) and ν2 + ν6 (b-type) were analyzed as asymmetric-rotor bands by taking account of the Coriolis interactions among the ν2 + ν3, ν2 + ν6, and ν2 + ν4 states, though none of the ν2 + ν4 band lines have yet been definitely identified. The main results in cm?1 units (with 2.5 times standard errors in the last digits given in parentheses) are: ν0 = 3238.45(1), A - B?= 8.252(3), B?= 1.2053(2), and B - C = 0.1719 (assumed) for ν2 + ν3; ν0 = 3000.10(1), A - B?= 8.125(46), B?= 1.2075(5), and B - C = 0.1693(14) for ν2 + ν6; and ν0 = 2904.6(48), A - B?= 8.225(54), B?= 1.2023(20), and B - C = 0.1522 (assumed) for ν2 + ν4; the effective Coriolis interaction terms are: ξ26,24a = 10.10(3)cm?1 and ξ23,26c = 0.96(3)cm?1 under the assumption that ξ23,24b = 1.2841cm?1. A second combination band 2ν2 + ν6 measured with lower resolution gave ν0 = 4734.81(6)cm?1. 相似文献
123.
Toshiaki Munakata Tomohiko Hirooka Kozo Kuchitsu 《Journal of Electron Spectroscopy and Related Phenomena》1978,13(3):219-228
Energy distributions of electrons ejected from polycrystalline surfaces of naphthacene, perylene and coronene by the impact of metastable He *, Ne * and Ar * atoms have been measured. Two types of peaks, which are similar to the “non-moving” and “moving” structures in photoelectron spectra, are observed in each spectrum. The non-moving structures (ca. 1 eV) for perylene and coronene are similar to those in the photoelectron spectra, whereas the relative intensities of the two non-moving structures for naphthacene (0.6 and 1.7 eV) are remarkably different from the corresponding structures in the photoelectron spectrum. The peak positions (but not necessarily their intensities and widths) for the moving structures for all the samples (> 2 eV) agree with those of the corresponding photoelectron spectra. The origin of these moving structures is ascribed to Penning ionization on the solid surface. 相似文献
124.
Kozo Bannai 《Journal of Combinatorial Theory, Series B》1978,24(2):181-188
Watkins (J. Combinatorial Theory 6 (1969), 152–164) introduced the concept of generalized Petersen graphs and conjectured that all but the original Petersen graph have a Tait coloring. Castagna and Prins (Pacific J. Math. 40 (1972), 53–58) showed that the conjecture was true and conjectured that generalized Petersen graphs G(n, k) are Hamiltonian unless isomorphic to G(n, 2) where n ≡ 5(mod 6). The purpose of this paper is to prove the conjecture of Castagna and Prins in the case of coprime numbers n and k. 相似文献
125.
The negative ion mass spectra of ferrocene and of a mixture of ferrocene with sulphur were studied. In the spectrum of the mixture, characteristic peaks of [C5H5 + Sn]? (n = 1, 2, 3 etc.) were observed. The structures of these ions are discussed. 相似文献
126.
127.
Kozo Arai Masamichi Shimizu Machiko Shimada 《Journal of polymer science. Part A, Polymer chemistry》1973,11(12):3271-3281
In order to study the termination reaction of polymer radicals in the viscous media of wool fibers, reduced, methylated, and S-carboxymethylated wool fibers were used for graft copolymerization of methyl methacrylate and styrene. With termination of poly(methyl methacrylate) radicals, two different termination reactions, recombination and disproportionation, were together involved in the grafting systems studied. The occurrences of two termination reactions in the system could be correlated with the mobility of the wool chain controlling the radical end mobility. With decreasing disulfide content in the fibers, disproportionation predominantly takes place among the mobilized chains. At a constant disulfide, the thiol content or the concentration of thiol anions becomes the determining factor for the termination reaction. A possible explanation for these phenomena in terms of the thiol and disulfide interchange reaction is presented. On the grafting of styrene, additional evidence was obtained that prevention and retardation of the interchange reactions followed mechanochemical bond scission of the disulfide and other covalent bonds and produced new free radicals which could initiate chain reactions. 相似文献
128.
The violet emission spectrum (B2ΣX2Σ) of the CN radical observed by the collision of HCN with metastable Ar(3P0,2) atoms was analyzed. The effective rotational temperature of the CN(B2Σ) radical, as estimated from a band envelope analysis, is about 2000°K. The distributions of the excess energy to vibration, rotation and translation are found to be 1.2 ± 0.2, 0.2 and 1.9 ± 0.3 eV, respectively. 相似文献
129.
A new bulky bromobenzene of the metacyclophane type was converted to an unsymmetrically substituted 1,4-diphos-phabutatriene whose spin-spin coupling constant (3Jpp) turned out to be larger, for the first time, than the 2Jpp value of the corresponding 1,3-diphosphaallene. 相似文献
130.
Morimoto Y Takaishi M Kinoshita T Sakaguchi K Shibata K 《Chemical communications (Cambridge, England)》2002,(1):42-43
The unknown stereostructure of 2-amino-3-cyclopropylbutanoic acid 1, a novel plant growth regulator isolated from the mushroom Amanita castanopsidis Hongo, was determined to be (2S,3S)-2 through its racemic and enantioselective syntheses employing the chelate-enolate Claisen rearrangement as a key step. 相似文献