全文获取类型
收费全文 | 3638篇 |
免费 | 182篇 |
国内免费 | 18篇 |
专业分类
化学 | 2532篇 |
晶体学 | 13篇 |
力学 | 76篇 |
数学 | 647篇 |
物理学 | 570篇 |
出版年
2023年 | 31篇 |
2022年 | 40篇 |
2021年 | 62篇 |
2020年 | 79篇 |
2019年 | 77篇 |
2018年 | 70篇 |
2017年 | 76篇 |
2016年 | 177篇 |
2015年 | 138篇 |
2014年 | 122篇 |
2013年 | 224篇 |
2012年 | 271篇 |
2011年 | 286篇 |
2010年 | 163篇 |
2009年 | 118篇 |
2008年 | 237篇 |
2007年 | 200篇 |
2006年 | 172篇 |
2005年 | 177篇 |
2004年 | 154篇 |
2003年 | 140篇 |
2002年 | 126篇 |
2001年 | 40篇 |
2000年 | 31篇 |
1999年 | 38篇 |
1998年 | 41篇 |
1997年 | 26篇 |
1996年 | 42篇 |
1995年 | 14篇 |
1994年 | 25篇 |
1993年 | 33篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 17篇 |
1985年 | 31篇 |
1984年 | 23篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 17篇 |
1980年 | 12篇 |
1979年 | 22篇 |
1978年 | 21篇 |
1977年 | 21篇 |
1975年 | 20篇 |
1974年 | 22篇 |
1973年 | 12篇 |
排序方式: 共有3838条查询结果,搜索用时 15 毫秒
41.
42.
43.
Summary We prove that every mixing
d
by automorphisms of a compact, connected, abelian group is mixing of all orders.Oblatum 5-II-1992The second author gratefully acknowledges support from NSF grant DMS-91-03056 at the Ohio State University 相似文献
44.
研究了基于微芯片电泳分离和电感耦合等离子体质谱的连接技术,并对不同形态的Cu和As进行了快速分离和检测. 相似文献
45.
New boracites containing nitrato- or fluoroanions that appear to be true low-pressure phases have been synthesized at superatmospheric pressures. The M3B7O13NO3 compounds (M = Co, Ni, Cu, Zn, Cd) transform rapidly and reversibly in the temperature region 300–500°C between probable orthorhombic and face centered cubic symmetry, while the M3B7O13F compounds (M = Mg, Mn, Fe, Co, Zn) appear to maintain rhombohedral symmetry up to their decomposition temperatures of 800–900°C. True high-pressure boracite-like phases containing F and Cr, Mn, Fe, or Co that decompose upon heating to M3B7O13F have also been isolated. 相似文献
46.
47.
With the use of the tritium monitoring network the samples of river water, air humidity and precipitation are collected and analysed for HTO in the vicinity of Temelín nuclear power plant. 相似文献
48.
A procedure for calculating the magnetic circular dichroism C/D ratio from density functional theory calculations is discussed. The method is simplified considerably through the application of group theory and the irreducible-tensor method and only requires integrals of the magnetic dipole moment operator over a few orbitals and published tables of symmetry factors. The implementation of the method is tested through application to several small and medium-sized molecules. 相似文献
49.
Metal-catalyzed di-tert-butylsilylene transfer was developed as a mild, operationally simple, functional-group-tolerant method for silacyclopropane formation. Di-tert-butylsilylene was transferred from cyclohexene silacyclopropane 1 to an alkene through the use of a metal salt. Silacyclopropanation occurred at temperatures as low as -27 degrees C when AgOTf or AgOC(O)CF(3) were used as catalysts. Complex silacyclopropanes were formed stereospecifically and diastereoselectively from functionalized alkenes. Silacyclopropanes reacted with various carbonyl compounds, including aldehydes, ketones, formate esters, and formamides, in an overall process that efficiently converts alkenes into oxasilacyclopentanes with defined stereochemistry. 相似文献
50.
K.D. Franz H. Tom Dieck U. Krynitz I.W. Renk 《Journal of organometallic chemistry》1973,64(3):361-366
Glyoxal- and diacetyl-bis(imine)metal tetracarbonyls (RNCR′CR′NR)M(CO)4 (M = Cr, Mo, W) are reduced with potassium in DME to give paramagnetic mono-anions. Their high-resolutior, ESR spectra show the hyperfine splittings of the magnetically active ligand atoms as well as the satellites of the metal isotopes 53Cr,95,97Mo and 183W. The coupling constants are discussed with respect to π-bonding mechanisms. 相似文献