全文获取类型
收费全文 | 716篇 |
免费 | 15篇 |
专业分类
化学 | 598篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 29篇 |
物理学 | 98篇 |
出版年
2021年 | 3篇 |
2020年 | 6篇 |
2018年 | 4篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 17篇 |
2013年 | 13篇 |
2012年 | 21篇 |
2011年 | 29篇 |
2010年 | 14篇 |
2009年 | 17篇 |
2008年 | 21篇 |
2007年 | 49篇 |
2006年 | 40篇 |
2005年 | 34篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 23篇 |
2001年 | 24篇 |
2000年 | 19篇 |
1999年 | 8篇 |
1998年 | 26篇 |
1997年 | 19篇 |
1996年 | 21篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 17篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 18篇 |
1973年 | 20篇 |
1972年 | 4篇 |
1938年 | 3篇 |
1905年 | 2篇 |
1884年 | 2篇 |
1883年 | 2篇 |
排序方式: 共有731条查询结果,搜索用时 109 毫秒
91.
Roger Parsons 《Journal of Electroanalytical Chemistry》1977,84(2):408-409
92.
Rate laws and kinetic parameters are reported for substitution at titanium(IV) complexes Ti(LL)2X2, where LLH=cyclopentadiene, the 4-pyrone ethylmaltol, several 4-pyridinones, and related ligands, and X=halide or alkoxide, in acetonitrile solution at 298.2 K. Reactivities are discussed in terms of the nature of the leaving group, the entering group and the non-leaving ligand LL?. Activation volumes of ?15 and ?12 cm3 mol?1 have been determined for thiocyanate attack at Ti(cp)2Cl2 and Ti(etmalt)2Cl2 respectively. Substitution mechanisms are discussed in the light of the kinetic parameters obtained. 相似文献
93.
CNDO/2 Calculations have been performed on the title compounds and on the anions derived from them. The results indicate that in the anion there is significant transannular transfer of charge to the 4-position. The amount of such transfer is effectively independent of the 4-substituent. It is concluded that the effect of the substituent upon the stability of the acid must be an important factor. 相似文献
94.
95.
Molar extinction coefficients of some carbohydrates viz. l-arabinose (C5H10O5), d-glucose (C6H12O6), d-mannose (C6H12O6), d-galactose (C6H12O6), d(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a
narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter
polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying
within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well. 相似文献
96.
Ohne Zusammenfassung 相似文献
97.
Kenneth D. Paull Robert H. Shoemaker Michael R. Boyd Jack L. Parsons Prabhakar A. Risbood William A. Barbera Mahenda N. Sharma David C. Baker Elli Hand Dominic A. Scudiero Anne Monks Michael C. Alley Manfred Grote 《Journal of heterocyclic chemistry》1988,25(3):911-914
A new tetrazolium salt, XTT, has been synthesized. XTT is reduced by a considerable variety of cell lines to a water-soluble formazan. XTT appears to merit further investigation as a reagent for broader application to cell culture assay systems. 相似文献
98.
Formic acid oxidation has been studied on Pt + Pd alloys of known surface composition using cyclic voltammetry. The results are interpreted in terms of a strongly bound (poisoning) intermediate which adsorbs only on the Pt atoms and a direct oxidation path which involves an intermediate occupying a single site and a second intermediate occupying two sites. Steady state oxidation currents on the alloys at potentials in the range of about 0.4 to 0.9 V are larger than expected from a linear combination of the currents on the pure metals. This effect may be due to the modification of metal properties at the junction between two types of metallic atoms. 相似文献
99.
100.