全文获取类型
收费全文 | 195篇 |
免费 | 0篇 |
专业分类
化学 | 93篇 |
数学 | 3篇 |
物理学 | 99篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 2篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 9篇 |
1986年 | 1篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有195条查询结果,搜索用时 46 毫秒
51.
The t-Butyloxycarbonyl (BOC) group on indoles and pyrroles can be removed cleanly and in high yield by simple thermolysis: no acid, no base, no solvent is required. 相似文献
52.
53.
54.
The total synthesis of didemnimide A and didemnimide B, novel predator-deterrent alkaloids from the Caribbean mangrove ascidian Didemnum conchyliatum, is described. 相似文献
55.
Qiang Xu T. Klimczuk Ton Gortenmulder Jacob Jansen M. A. McGuire R. J. Cava Henny W. Zandbergen 《ChemInform》2009,40(42):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
56.
Extensive new high-temperature, high-resolution FTIR emission spectroscopy measurements for the five common isotopomers of GeO are combined with previous diode laser and microwave measurements in combined isotopomer analyses. New Dunham expansion parameters and an accurate analytical potential energy function are determined for the ground X1Sigma+ state. Copyright 1999 Academic Press. 相似文献
57.
58.
Sundaramoorthi Rajeswari Akinbo A. Adesomoju Michael P. Cava 《Journal of heterocyclic chemistry》1989,26(3):557-564
Preparation of two new analogs 5 and 6 of the antitumor antibiotic CC-1065 1 are described. These compounds represent structural modifications of the active analogs 3 and 2 respectively, in which the dienone A-unit has been replaced by the tricyclic achiral gramine unit 4 . Modest cytotoxicity was exhibited by compounds 5 and 6 . 相似文献
59.
G.C. Lau B.D. Muegge T.M. McQueen E.L. Duncan R.J. Cava 《Journal of solid state chemistry》2006,179(10):3126-3135
Synthesis and crystal structures are described for the compounds Ln2(Ti2−xLnx)O7−x/2, where Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu, and x ranges from 0 to 0.67. Rietveld refinements of X-ray powder diffraction data indicate that in the Tb and Dy titanate pyrochlores, the extra Ln3+ cations mix mainly on the Ti4+ site with little disorder on the original Ln3+ site. For the smaller rare earths (Ho-Lu), stuffing additional lanthanide ions results in a pyrochlore to defect fluorite transition, where the Ln3+ and Ti4+ ions become completely randomized at the maximum (x=0.67). Initial magnetic characterization for the fully stuffed x=0.67 samples for Ln=Tb-Yb shows no long range ordering down to 2 K, and only partial saturation of the full expected magnetic moment under applied fields up to 5 T. In all of these Ln-Ti-O pyrochlores, the addition of magnetic Ln3+ in place of non-magnetic Ti4+ adds edge sharing tetrahedral spin interactions to a normally corner sharing tetrahedral network of spins. The increase in spin connectivity in this family of solid solutions represents a new avenue for investigating geometrical magnetic frustration in the rare earth titanate pyrochlores. 相似文献
60.
The preparation and physical characterization of non-stoichiometric Ru2Ge3+x (0≤x≤1) are reported for the first time. The defect TiSi2-type chimney-ladder structure is maintained for the full stoichiometry range. The resistivity of Ru2Ge3+x increases systematically with x from 300 mΩ cm, x=0 -3 Ω cm, x=1 at 300 K. The temperature dependence is consistent with a variable range-hopping mechanism for x≥0.6. The Seebeck coefficients of samples do not evolve simply with x. A low thermal conductivity (κ300 K=0.03 W/K cm) suggests that Ru2Ge3 has some of the properties of a phonon-glass-electron-crystal. The low value of the thermoelectric figure of merit ZT=3.2×10−3 (T=300 K) calculated for Ru2Ge3 is due primarily to a low conductivity. 相似文献