全文获取类型
收费全文 | 264篇 |
免费 | 8篇 |
专业分类
化学 | 83篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 70篇 |
物理学 | 111篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 16篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1989年 | 3篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1973年 | 6篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1941年 | 1篇 |
1939年 | 1篇 |
1937年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有272条查询结果,搜索用时 15 毫秒
71.
72.
Dr. Karl P. J. Gustafson Dr. Tamás Görbe Dr. Gonzalo de Gonzalo-Calvo Ning Yuan Cynthia L. Schreiber Dr. Andrey Shchukarev Dr. Cheuk-Wai Tai Prof. Dr. Ingmar Persson Prof. Dr. Xiaodong Zou Prof. Dr. Jan-E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(39):9174-9179
Herein, we report on the use a biohybrid catalyst consisting of palladium nanoparticles immobilized on cross-linked enzyme aggregates of lipase B of Candida antarctica (CalB CLEA) for the dynamic kinetic resolution (DKR) of benzylic amines. A set of amines were demonstrated to undergo an efficient DKR and the recyclability of the catalysts was studied. Extensive efforts to further elucidate the structure of the catalyst are presented. 相似文献
73.
Brian G. Alberding Malcolm H. Chisholm Terry L. Gustafson Carly R. Reed Namrata Singh Claudia Turro 《Journal of Cluster Science》2009,20(2):307-317
The photophysical properties of the title compound have been studied by fs and ns transient absorption spectroscopy. The electronic
absorption spectrum consists of three principle absorptions assigned to terpy 1LLCT at ~300 nm, ruthenium (II) t2g6 to terpy 1MLCT at ~470 nm and Mo2 δ to terpycarboxylate at ~670 nm. The compound shows weak room temperature emission in THF solution at ~1,100 nm when excited
into each of the aforementioned bands. This emission is assigned to the T1 state, 3MMδδ*. Transient absorption spectroscopy indicates a lifetime for T1 of 9.6 μs.
This paper is dedicated to Prof. C. N. R. Rao. 相似文献
74.
Wenwei Huang Janice Chin Luke Karpinski Gary Gustafson Carmen M. Baldino Libing Yu 《Tetrahedron letters》2006,47(28):4911-4915
Metal iodide mediated three-component reactions of cyclopropanecarboxylic thioesters 1, aldehydes, and amines were developed. The initial products, pyrrolidines 2 were obtained in 39-73% yields, which could further be converted to lactams 4, via sequential reactions of a retro-aza-Michael addition and an intramolecular cyclization. This methodology provided facile access to analogs of both pyrrolidines 2 and lactams 4. 相似文献
75.
Burdzinski GT Middleton CT Gustafson TL Platz MS 《Journal of the American Chemical Society》2006,128(46):14804-14805
Photolysis of phenyl and o-biphenylyl azide (at 270 nm) releases vibrationally excited singlet nitrene which isomerizes to the corresponding hot 1,2-didehydroazepine at a rate competitive with thermal relaxation. Using ultrafast vibrational spectroscopy we observe the formation of vibrationally excited 1,2-4,6-azacycloheptatetraene (1,2-didehydroazepine) in picoseconds following photolysis of phenyl azide in chloroform and o-biphenylyl azide in acetonitrile at ambient temperature. 相似文献
76.
Burdzinski G Hackett JC Wang J Gustafson TL Hadad CM Platz MS 《Journal of the American Chemical Society》2006,128(41):13402-13411
The photochemistry of para- and ortho-biphenylyl azides and 1-naphthyl azide was studied by ultrafast spectroscopy. In every case, the singlet azide second excited states were observed by transient absorption spectroscopy and were found to have lifetimes of hundreds of femtoseconds. The decay of the S(2) states of the azides was accompanied by the growth of transient absorption of the corresponding singlet nitrenes. The intermediate S(1) state of the azides could not be observed due to its low instantaneous concentration resulting from fast fragmentation and nitrene formation. Quantum chemical calculations predict that the S(2) state of the azide is bound and that there is a much lower barrier toward arylnitrene formation from the S(1) state of the azide. Vibrational cooling of para-biphenylnitrene (11 ps) was experimentally observed. The lifetime of singlet ortho-biphenylnitrene was 16 ps in acetonitrile and was not affected by perdeuteration of the aryl ring. The lifetime of singlet 1-naphthylnitrene is 12 ps in acetonitrile at ambient temperature. 相似文献
77.
We study solutions of the focusing energy-critical nonlinear heat equation in . We show that solutions emanating from initial data with energy and -norm below those of the stationary solution W are global and decay to zero, via the “concentration-compactness plus rigidity” strategy of Kenig–Merle [33], [34]. First, global such solutions are shown to dissipate to zero, using a refinement of the small data theory and the -dissipation relation. Finite-time blow-up is then ruled out using the backwards-uniqueness of Escauriaza–Seregin–Sverak [17], [18] in an argument similar to that of Kenig–Koch [32] for the Navier–Stokes equations. 相似文献
78.
The problem was motivated by Borvka's definitions of the carrier and the associated carrier. The inverse carrier problem is precisely defined and partially solved. Examples are given. 相似文献
79.
The strong Chebyshev distribution and the Chebyshev orthogonal Laurent polynomials are examined in detail. Explicit formulas are derived for the orthogonal Laurent polynomials, uniform convergence of the associated continued fraction is established, and the zeros of the Chebyshev L-polynomials are given. This provides another well-developed example of a sequence of orthogonal L-polynomials 相似文献
80.
David K. Hoffman Omar A. Sharafeddin Donald J. Kouri Michael Carter Naresh Nayar John Gustafson 《Theoretical chemistry accounts》1991,79(3-4):297-311
Summary Results of our initial study of the use of parallel architecture super-computers in solving time-dependent quantum scattering equations are reported. The specific equations solved are obtained from the time-dependent Lippmann-Schwinger integral equation by means of a quadrature approximation to the time integral. This leads to a modified Cayley transform algorithm in which the primary computational step is a matrix-vector multiplication. Implementation has been carried out both for the MasPar MP-1 and the NCUBE 6400 parallel machines. The codes are written in a modular form that greatly facilitates porting from one machine architecture to another. Both parallel machines prove to be more powerful for this application than the serial architecture VAX 8650. Specific analysis of machine performance is given.Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. 2-7405-ENG-82. This research was supported by the Division of Chemical Sciences and Applied Mathematical Sciences, Office of Basic Energy SciencesR.A. Welch Predoctoral Fellow under R.A. Welch Foundation Grant E-608Supported in part under National Science Foundation Grant CHE89-07429 相似文献