全文获取类型
收费全文 | 354篇 |
免费 | 6篇 |
国内免费 | 5篇 |
专业分类
化学 | 198篇 |
力学 | 5篇 |
数学 | 101篇 |
物理学 | 61篇 |
出版年
2022年 | 3篇 |
2020年 | 5篇 |
2018年 | 3篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 15篇 |
2013年 | 13篇 |
2012年 | 17篇 |
2011年 | 13篇 |
2010年 | 16篇 |
2009年 | 9篇 |
2008年 | 19篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 18篇 |
2003年 | 22篇 |
2002年 | 6篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1994年 | 8篇 |
1992年 | 4篇 |
1990年 | 5篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1979年 | 7篇 |
1977年 | 7篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1964年 | 3篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1957年 | 3篇 |
1907年 | 2篇 |
排序方式: 共有365条查询结果,搜索用时 31 毫秒
71.
We introduce the algebra of smoothing Mellin and Green symbols in a pseudodifferential calculus for manifolds with edges. In addition, we define scales of weighted Sobolev spaces with asymptotics based on the Mellin transform and analyze the mapping properties of the operators on these spaces. This will allow us to obtain complete information on the regularity and asymptotics of solutions to elliptic equations on these spaces. 相似文献
72.
73.
Elmar Hecht 《无机化学与普通化学杂志》2000,626(3):759-765
Preparation, Properties, and Molecular Structures of Dimethylaminomethyl Ferrocenyl Compounds of selected Elements of Group 13 and 14 Dimethylmetalchlorides of gallium and indium react with dimethylaminomethylferrocenyllithium (FcNLi) to give the corresponding dimethylmetaldimethylaminomethylferrocenes 1 and 2 [Me2MFcN; M=Ga, In]. In a similar manner dialkylmetaldichlorides of germanium and tin yield the expected chlordialkylmetaldimethylaminomethylferrocenes 3 – 5 [R2(Cl)MFcN; M=Ge; R = Me ( 3 ), M=Sn; R=Me ( 4 ), Ph ( 5 )]. In a reaction of Me3Al and Me2AlCl with dimethylaminomethylferrocene the formation of the 1 : 1 adducts 7 and 8 could be observed. All compounds were characterised by 1H and 13C nmr spectroscopy. The molecular structures of 1 , 3 , 4 and 7 were determined. 3 and 4 build in contrast to 1 monomeric molecules with chelat rings as a result of the M–N coordination. Compound 7 consist of monomeric molecules with 4 coordinated Al atoms. 相似文献
74.
Intra- and inter-chain fluctuations in entangled polymer melts in bulk and confined to pore channels
Rainer Kimmich Nail Fatkullin Ralf-Oliver Seitter Elmar Fischer Uwe Beginn Martin Mller 《Macromolecular Symposia》1999,146(1):109-115
It is known that topological restraints by “chain entanglements” severely affect chain dynamics in polymer melts. In this field-cycling NMR relaxometry and fringe-field NMR diffusometry study, melts of linear polymers in bulk and confined to pores in a solid matrix are compared. The diameter of the pore channels was 10 nm. It is shown that the dynamics of chains in bulk dramatically deviate from those observed under pore constraints. In the latter case, one of the most indicative signatures of the reptation model is verified 28 years after its prediction by de Gennes: The frequency and molecular mass dependencies of the spin-lattice relaxation time obey the power law T! ∝ M0 v3/4 on a time scale shorter than the longest Rouse relaxation time τR. The mean squared segment displacement in the pores was also found to be compatible to the reptation law < r2>∝ M−1/2t1/2 predicted for τR < t < τd, where τd is the so-called disengagement time. Contrary to these findings, bulk melts of entangled polymers show frequency and molecular mass dependencies significantly different from what one expects on the basis of the reptation model. The data can however be described with the aid of the renormalized Rouse theory. 相似文献
75.
Marc Pignot Christoph Siethoff Michael Linscheid Elmar Weinhold 《Angewandte Chemie (International ed. in English)》1998,37(20):2888-2891
How to outwit a methyltransferase: Methyltransferases (Mtases) catalyze the transfer of the activated methyl group from the cofactor S-adenosyl-L -methionine ( 1 ) to acceptors R within a large variety of biomolecules. Through the use of the cofactor analogue 2 a whole nucleoside was coupled to DNA in a Mtase-catalyzed reaction. 相似文献
76.
Peter Beiersdorfer Natalie Hell Dmytro Panchenko Greg V. Brown Elmar Träbert Richard L. Kelley Caroline A. Kilbourne F. Scott Porter 《X射线光谱测定》2020,49(1):21-24
We report a measurement of the two X-ray transitions that proceed from the and (1s22s1/22p63p1/2)J = 1 upper levels to the (1s22s22p6)J = 0 ground level in neonlike Eu53+ (Z = 63), that is, near the previously documented avoided crossing of the two upper levels at Z = 68. The measurement was carried out using the calorimeter spectrometer on the Livermore EBIT-I electron beam ion trap. It affirms the trends set by the neighboring neonlike ions both in terms of the relative intensity of the two lines and in terms of the magnitude of disagreement with theoretical energy level predictions. 相似文献
77.
78.
79.
80.
G. Schwedt Christian Reiter Rolf Uthemann Elmar Grabert 《Analytical and bioanalytical chemistry》1997,359(2):155-160
The development of the bacterial luminescence test to an automated biomonitor is described. The computer controlled system was optimized by varying the following parameters: intermixture of the analyte solution and bacteria suspension, intensity and period of stirring during intermixture, delay time for temperature equalization, long-time stability of the bacteria and evaluation of the measured signals. All measurements were carried out using organic and inorganic pollutants, e.g. formaldehyde, phenol, 2,4-dichlorophenol, cyanide and lead ions. Five-minute inhibition curves from a number of single runs are presented. 相似文献