全文获取类型
收费全文 | 7308篇 |
免费 | 227篇 |
国内免费 | 27篇 |
专业分类
化学 | 5351篇 |
晶体学 | 85篇 |
力学 | 99篇 |
数学 | 295篇 |
物理学 | 1732篇 |
出版年
2022年 | 31篇 |
2021年 | 52篇 |
2020年 | 85篇 |
2019年 | 95篇 |
2018年 | 76篇 |
2017年 | 56篇 |
2016年 | 135篇 |
2015年 | 131篇 |
2014年 | 160篇 |
2013年 | 333篇 |
2012年 | 343篇 |
2011年 | 418篇 |
2010年 | 219篇 |
2009年 | 239篇 |
2008年 | 436篇 |
2007年 | 380篇 |
2006年 | 396篇 |
2005年 | 365篇 |
2004年 | 353篇 |
2003年 | 284篇 |
2002年 | 279篇 |
2001年 | 168篇 |
2000年 | 188篇 |
1999年 | 116篇 |
1998年 | 85篇 |
1997年 | 85篇 |
1996年 | 86篇 |
1995年 | 55篇 |
1994年 | 84篇 |
1993年 | 103篇 |
1992年 | 106篇 |
1991年 | 84篇 |
1990年 | 75篇 |
1989年 | 65篇 |
1988年 | 81篇 |
1987年 | 87篇 |
1986年 | 82篇 |
1985年 | 123篇 |
1984年 | 120篇 |
1983年 | 52篇 |
1982年 | 92篇 |
1981年 | 92篇 |
1980年 | 75篇 |
1979年 | 72篇 |
1978年 | 61篇 |
1977年 | 71篇 |
1976年 | 59篇 |
1975年 | 49篇 |
1974年 | 54篇 |
1973年 | 45篇 |
排序方式: 共有7562条查询结果,搜索用时 15 毫秒
991.
Y. Suzuki 《Nuclear Physics A》1984,430(3):539-556
The full Breit hamiltonian, including the Darwin term and relativistic kinetic-energy correction, has been used to construct resonating group kernels in analytic form for the six-quark NN system. The nonlocal kernels have been converted to equivalent local potentials using the WKB approximation based on their Wigner transforms. The equivalent local potentials have been confirmed to be rather insensitive to a choice of parameters and to be fairly accurate by comparing with the phase shifts and the wave functions obtained with the RGM equation. The results indicate the importance of the Darwin term. The term leads to a large reduction of the strong repulsive cores given by the color magnetic interaction and makes the resulting potentials less repulsive than those which neglect this term. The relative importance of the various components in the Breit interaction and of the quark-gluon exchange diagrams is made clear. 相似文献
992.
Yoshio Hamashima Tadatoshi Kubota Koji Ishikura Wataru Nagata 《Tetrahedron letters》1979,20(51):4943-4946
7-Epi-1-oxacephem was obtained by stereospecific, intramolecular etherification of alcohol prepared from 7-epicephems via aldehyde or formate. Synthesis of the 3-acetoxymethyl analogwas unsuccessful. Biologically active 1-oxacephems were derived from by known processes. 相似文献
993.
994.
Koji Yamakawa auMasato Kobayashi Shotaro Hinata Tsuyoshi Satoh 《Tetrahedron letters》1979,20(40):3871-3872
Stereoselective synthesis of (±)-phomenone, a phytotoxic metabolite from the fungus Phoma exigua, and (±)-3-epiphomenone is described. 相似文献
995.
996.
Aija Zirnis Joseph K. Suzuki Donald E. Dickson Robert A. Laitar Albert A. Manian 《Journal of heterocyclic chemistry》1977,14(1):107-112
The synthesis of 7-hydroxy, 8-hydroxy and 7,8-dihydroxy prochlorperazines (3a) and per-phenazines (3b) is reported. The parent ehlorophenothiazines were prepared analogously to previously reported chlorpromazine (3e) metabolite syntheses. The prochlorperazine side chain was introduced in one step using 1-(3-chloropropyl)-4-methylpiperazine and the perphenazine side chain in two steps, first reaction with 1-bromo-3-chloropropane followed by reaction with 1-piperazineethanol. The methoxymethyleneoxy O-proteetive groups were removed under mild conditions using methanolic hydrogen chloride. The preparations of 7-hydroxydesmethylprochlorperazine and 7-hydroxychlorpromazine quaternary methyl iodide are also reported. 相似文献
997.
998.
999.
The heat capacity of 1T-TaS2 has been measured over the temperature range including the successive phase transitions (140 K–370 K) by an adiabatic calorimeter. There are three transitions in the measured temperature range, two first-order transitions (at about 226 K (T1) and about 353.5 K (T3)) and one small anomaly at about 283 K (T2) with a broad peak. The transition enthalpies are as follows; ΔH1=52±5 cal·mol-1, ΔH2=7.5±2 cal· mol-1 and ΔH3=122±8cal·mol-1. 相似文献
1000.
A simple synthetic method of α-arylalkanoic acids was accomplished by the use of a novel 1,2-rearrangement of the aryl group and this method was applied to the syntheses of some biologically important substances. 相似文献