全文获取类型
收费全文 | 622篇 |
免费 | 5篇 |
国内免费 | 4篇 |
专业分类
化学 | 312篇 |
力学 | 115篇 |
数学 | 120篇 |
物理学 | 84篇 |
出版年
2018年 | 6篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 28篇 |
2012年 | 11篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 19篇 |
2008年 | 22篇 |
2007年 | 15篇 |
2006年 | 16篇 |
2005年 | 20篇 |
2004年 | 13篇 |
2003年 | 12篇 |
2002年 | 22篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 15篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 19篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1973年 | 22篇 |
1972年 | 7篇 |
1971年 | 4篇 |
1970年 | 9篇 |
1969年 | 8篇 |
1968年 | 8篇 |
1967年 | 9篇 |
1965年 | 6篇 |
排序方式: 共有631条查询结果,搜索用时 15 毫秒
61.
W. Franklin Gilmore David W. Morton 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):185-187
Abstract Stabilized carbanions such as the α-carbanions of carboxylic acid esters react with sulfamoyl chlorides by nucleophilic displacement at chlorine which results in chlorination of the carbanion. Thus direct sulfamoylation of these carbanions with sulfamoyl chlorides fails. Conversion of sulfamoyl chlorides to N-sulfonylamines followed by addition of carbanions at -78°C results in sulfamoylation of the carbanion. The method has not been successful with carbanions from diethyl acetamidomalonate and ethyl diphenylacetate. 相似文献
62.
Tianhong Zhang Morton H. Litt Charles E. Rogers 《Journal of polymer science. Part A, Polymer chemistry》1994,32(7):1323-1330
Three poly(ethylene oxide-co-ethylene sulfide)s with oxygen to sulfur ratios of 2/1, 2/2, and 1/2 were prepared by phase-transfer catalyzed polycondensations of (1) sodium sulfide and 1,2-bis (2-chloroethoxy)ethane, (2) 1,2-ethanedithiol and 1,2-bis(2-chloroethoxy)ethane, and (3) 1,2-ethanedithiol and 2-chloroethyl ether, respectively. A buffered solution with pH between the pKa of the monothiol (RSH) and the pKa2 of the dithiol (HS–R–SH), or H2S, was needed to obtain high molecular weight polymers, which suggests that nucleophiles transfer and react as monoanions rather than dianions. These poly(ethylene oxide-co-ethylene sulfide)s were oxidized completely to poly(ethylene oxide-co-ethylene sulfone)s using 3-chloroperoxybenzoic acid as oxidant. Both the final polymers and the precursors have regular sequenced structures and are semicrystalline. As expected, their glass transition temperatures and melting points increase and solubilities decrease with the decrease of ether oxygen to sulfur ratio. © 1994 John Wiley & Sons, Inc. 相似文献
63.
Colin J.H. Morton Richard L. Riggs Nicholas J. Westwood Alexandra M.Z. Slawin 《Tetrahedron》2005,61(3):727-738
Ethyl 2-aryl-4,5-dihydro-5-oxopyrrole-3-carboxylates react with esters or acyl halides in the presence of a strong base to give 4-acyl derivatives, which exist predominantly as either E- or Z-enols. These are cyclised, either in solution at temperatures >200 °C or by microwave irradiation, to 3,6-disubstituted 1H-furo[3,4-c]pyrrolediones which, after N-protection, are convertible by reaction with primary amines into novel N,N′-disubstituted DPP derivatives. 相似文献
64.
Shah BK Neckers DC Shi J Forsythe EW Morton D 《The journal of physical chemistry. A》2005,109(34):7677-7681
Anthanthrene (1) derivatives substituted at the 4,10 and 6,12 positions (2-6) were synthesized as promising candidates for organic light emitting diodes (OLEDs). The emission of these compounds can be manipulated in the blue region (lambda(max) = 437-467 nm) through structural modifications. Photophysical and electrochemical properties (phi(F) = 0.20-0.47; tau(F) = 2.97-6.06 ns; HOMO-LUMO energy gap = 2.25-2.56 eV) as well as geometry optimized structures of 1-6 are reported. 相似文献
65.
By employing Senanayake's oxathiazolidine-2-oxide reagent, a collection of sulfinamides was prepared and provided the first examples of sulfinamides promoting the allylation of benzaldehyde and N-benzoylhydrazones with allyltrichlorosilane. The optimum sulfinamide-derived Lewis base promoter displays comparable activity to the best sulfinyl-based Lewis bases reported. The use of bis-sulfoxides is also discussed. 相似文献
66.
67.
Morton E. Gurtin Terrance D. Ralston 《International Journal of Solids and Structures》1974,10(9):933-943
This paper establishes the convergence of the continuous-time Galerkin technique as applied to quasi-static, linear viscoelasticity. 相似文献
68.
Sarah R. Dennison Leslie H.G. Morton Andrea J. Shorrocks Frederick Harris David A. Phoenix 《Colloids and surfaces. B, Biointerfaces》2009,68(2):225-230
Aurein 2.5 (GLFDIVKKVVGAFGSL-NH2) is an uncharacterised antimicrobial peptide. At an air/water interface, it exhibited strong surface activity (maximal surface pressure 25 mN m−1) and molecular areas consistent with the adoption of α-helical structure orientated either perpendicular (1.72 nm2 molecule−1) or parallel (3.6 nm2 molecule−1) to the interface. Aurein 2.5 was strongly antibacterial, exhibiting a minimum inhibitory concentration (MIC) of 30 μM against Bacillus subtilis and Escherichia coli. The peptide induced maximal surface pressure changes of 9 mN m−1 and 5 mN m−1, respectively, in monolayers mimicking membranes of these organisms whilst compression isotherm analysis of these monolayers showed ΔGMix > 0, indicating destabilisation by Aurein 2.5. These combined data suggested that toxicity of the peptide to these organisms may involve membrane invasion via the use of oblique orientated α-helical structure. The peptide induced strong, comparable maximal surface changes in monolayers of DOPG (7.5 mN m−1) and DOPE monolayers (6 mN m−1) suggesting that the membrane interactions of Aurein 2.5 were driven by amphiphilicity rather than electrostatic interaction. Based on these data, it was suggested that the differing ability of Aurein 2.5 to insert into membranes of B. subtilis and E. coli was probably related to membrane-based factors such as differences in lipid packing characteristics. The peptide was active against both sessile E. coli and Staphylococcus aureus with an MIC of 125 μM. The broad-spectrum antibacterial activity and non-specific modes of membrane action used by Aurein 2.5 suggested use as an anti-biofilm agent such as in the decontamination of medical devices. 相似文献
69.
Jeffrey Colin Morton 《Applied Categorical Structures》2011,19(4):659-707
This paper describes a relationship between essentially finite groupoids and two-vector spaces. In particular, we show to construct two-vector spaces of Vect-valued presheaves on such groupoids. We define two-linear maps corresponding to functors between groupoids in both a covariant and contravariant way, which are ambidextrous adjoints. This is used to construct a representation—a weak functor—from Span(FinGpd) (the bicategory of essentially finite groupoids and spans of groupoids) into 2Vect. In this paper we prove this and give the construction in detail. 相似文献
70.
Morton E. Gurtin William O. Williams 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1967,18(1):132-135
Zusammenfassung Es wird eine Methode beschrieben für die Charakterisierung von Stoff-Phasen durch Angabe der Symmetrie-Gruppe als Funktion der Deformation und Temperatur. Wenn in einem elastischen Stoff die Phase durch Dichte und Temperatur bestimmt wird, dann gelten die meisten der üblichen Resultate für die Gesamt-Symmetrie-Gruppe auch für die Gruppe, die einer gegebenen Phase entspricht. 相似文献