全文获取类型
收费全文 | 1020篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
化学 | 773篇 |
晶体学 | 16篇 |
力学 | 6篇 |
数学 | 80篇 |
物理学 | 161篇 |
出版年
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 18篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 8篇 |
2013年 | 69篇 |
2012年 | 27篇 |
2011年 | 50篇 |
2010年 | 24篇 |
2009年 | 31篇 |
2008年 | 47篇 |
2007年 | 43篇 |
2006年 | 48篇 |
2005年 | 42篇 |
2004年 | 37篇 |
2003年 | 41篇 |
2002年 | 42篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 24篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 20篇 |
1980年 | 35篇 |
1979年 | 24篇 |
1978年 | 23篇 |
1977年 | 28篇 |
1976年 | 7篇 |
1975年 | 15篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1971年 | 3篇 |
1968年 | 4篇 |
1958年 | 3篇 |
排序方式: 共有1036条查询结果,搜索用时 15 毫秒
141.
Such an asymmetric [2,3]-Wittig variant that is both highly enantio- and erythro-selective is described within the context of the chiral synthesis of the insect pheromones, (3, 4)-4-methyl-3-heptanol and ()-4-methyl-3-heptanone. 相似文献
142.
143.
It has been shown by Bogdanova and Boukliev [1] that there exist a ternary [38,5,24] code and a ternary [37,5,23] code. But it is unknown whether or not there exist a ternary [39,6,24] code and a ternary [38,6,23] code. The purpose of this paper is to prove that (1) there is no ternary [39,6,24] code and (2) there is no ternary [38,6,23] code using the nonexistence of ternary [39,6,24] codes. Since it is known (cf. Brouwer and Sloane [2] and Hamada and Watamori [14]) that (i) n3(6,23) = 38> or 39 and d3(38,6) = 22 or 23 and (ii) n3(6,24) = 39 or 40 and d3(39,6) = 23 or 24, this implies that n3(6,23) = 39, d3(38,6) = 22, n3(6,24) = 40 and d3(39,6) = 23, where n3<>(k,d) and d<>3(n,k) denote the smallest value of n and the largest value of d, respectively, for which there exists an [n,k,d] code over the Galois field GF(3). 相似文献
144.
145.
146.
147.
Hiroshi Masuhara Noboru Mataga Shigeo Tazuke Toshiro Murao Iwao Yamazaki 《Chemical physics letters》1983,100(5):415-419
Using total internal reflection, the possibility of a subnanosecond fluorescence spectroscopy for elucidating photophysical and photochemical processes of polymer surface is demonstrated. The thickness which can be studied under the present experimental conditions is of the order of 0.01 μm. 相似文献
148.
N. Kunitomi Y. Tsunoda N. Wakabayashi R.M. Nicklow H.G. Smith 《Solid State Communications》1978,25(11):921-924
The phonon dispersion relations of disordered alloys Ni1-xPtx were measured for five specimens covering the full range of atomic concentration by means of neutron inelastic scattering. At the resonant frequencies well separated double peak structures were observed in the phonon spectra. For the specimens with , the energy splitting of the phonon dispersion curve for the L-branch takes place at a higher frequency than that for the T-branch. The maximum phonon energy decreases with increasing Pt concentration but deviates from the theoretical prediction based on the mass defect CPA model. For x = 0.95 the localized mode cannot be observed as a well defined peak and does not seem to be split off from the main phonon band. 相似文献
149.
Kazuo Furihata Haruo Seto Muneki Ohuchi Noboru Otake 《Magnetic resonance in chemistry : MRC》1983,21(10):624-627
A new method based on the combination of selective proton decoupling and INEPT is explained in detail. This technique, named selective INEPT (SEL-INEPT), is a useful and sensitive method for the 13C NMR assignment of methylene carbons with non-equivalent protons. The 13C NMR spectrum of monensin has been analysed by the application of this technique. 相似文献
150.