全文获取类型
收费全文 | 413篇 |
免费 | 5篇 |
国内免费 | 13篇 |
专业分类
化学 | 233篇 |
晶体学 | 2篇 |
力学 | 6篇 |
数学 | 95篇 |
物理学 | 95篇 |
出版年
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 9篇 |
2011年 | 19篇 |
2010年 | 15篇 |
2009年 | 17篇 |
2008年 | 18篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 15篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1974年 | 3篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1938年 | 2篇 |
1931年 | 4篇 |
1930年 | 2篇 |
1927年 | 2篇 |
排序方式: 共有431条查询结果,搜索用时 0 毫秒
81.
82.
83.
E. Cattelain L. Bliecq C. H. Troy P. Fr. Sharp A. Schneck W. Strack und G. Roeder 《Fresenius' Journal of Analytical Chemistry》1931,83(5-6):236-238
Ohne Zusammenfassung 相似文献
84.
85.
Mamou-Mani A Brian Sharp D Meurisse T Ring W 《The Journal of the Acoustical Society of America》2012,131(1):728-736
For large-scale woodwind instrument makers, producing instruments with exactly the same playing characteristics is a constant aim. This paper explores manufacturing consistency by comparing five Howarth S10 student model oboes. Psychophysical testing involving nine musicians is carried out to investigate perceived differences in the playing properties of the two Howarth oboes believed to be most dissimilar. Further testing, involving one musician and combinations of the five oboes, provides information regarding the relative playabilities of the instruments at specific pitches. Meanwhile, input impedance measurements are made on the five oboes for fingerings throughout the playing range and their bore profiles are measured. The main findings are (1) the two instruments used in the preliminary psychophysical testing are perceived as identical by most of the musicians, although differences are identified by two players when playing the note F6 and by one player when playing in the lowest register, (2) a variation in the playability of F6 across the five oboes is due to differences in the elevation of the C key, and (3) variations in the playing properties in the lowest register are related to input impedance differences,which, in turn, appear to be at least partly due to bore profile differences. 相似文献
86.
W B Sharp P J Daff W S McNeil P Legzdins 《Journal of the American Chemical Society》2001,123(26):6272-6282
Treatment of [Cp*Mo(NO)Cl(mu-Cl)](2) with magnesium (Me(2)Mg.dioxane, MeMgCl) or aluminum (Me(3)Al) methylating reagents affords the known compound [Cp*Mo(NO)Me(mu-Cl)](2) (1). Similar treatment of the dichloro precursor with MeLi in ethereal solvents generates an equimolar mixture of 1 and the trimethyl "ate" complex, Cp*MoMe(3)(NO-Li(OEt(2)(n)), (2-Et(2)O). Reaction of 2-Et(2)O with a source of [Me](+) forms Cp*MoMe(3)(=N-OMe)(3), a rare terminal alkoxylimido complex. Metathesis of the chloro ligands of [Cp*Mo(NO)Cl(mu-Cl)](2) by MeLi in toluene at low temperatures produces the target dimethyl complex, Cp*Mo(NO)Me(2) (4), in 75% isolated yield. In solution, 4 is predominantly a monomeric species, whereas in the solid state it adopts a dimeric or oligomeric structure containing isonitrosyl bridges as indicated by IR and (15)N/(13)C NMR spectroscopies. Hydrolysis of 4 affords meso- and rac-[Cp*Mo(NO)Me](2)(mu-O) (5), and the reactions of 4 with a range of Lewis bases, L, to form the 18e adducts Cp*Mo(NO)(L)Me(2) (e.g., Cp*Mo(NO)(PMe(3))Me(2) (7)), have established it to be the most electrophilic complex of its family. Acidolysis of the methyl groups of 4 is also facile. Most notably, 4 is thermally unstable in solution and undergoes isomerization via nitrosyl N-O bond cleavage to its oxo(imido) form, Cp*Mo(NMe)(O)Me (11), which is isolable from the final reaction mixture as the mu-oxo-bridged adduct formed by 4 and 11, i.e., Cp*Mo(NO)Me(2)(mu-O)Cp*Mo(NMe)Me (4 <-- 11). The rate of this isomerization is significantly faster for the tungsten dimethyl complex; hence, Cp*W(NO)Me(2) (12) is not isolable free of a supporting donor interaction and can only be isolated as Cp*W(NO)Me(2)(mu-O)Cp*W(NMe)Me (12 <-- 13) or Cp*W(NO)Me(2)(PMe(3)) (14) adducts. 相似文献
87.
Thomas R. Sharp Kyle R. LeemanD.Eugene Bryant George J. Horan 《Tetrahedron letters》2003,44(8):1559-1561
Photostability challenge of ziprasidone in solution shows that the benzisothiazole moiety undergoes isomerization to the corresponding benzthiazole. A model compound, 3-piperazinyl-1,2-benzisothiazole, also undergoes this photoisomerization. Identification of the products has been confirmed by synthesis of the proposed molecules. 相似文献
88.
89.
Richard Sharp 《Geometriae Dedicata》2007,125(1):63-74
Let Γ be a convex co-compact group of isometries of a CAT(−1) space X and let Γ0 be a normal subgroup of Γ. We show that, provided Γ is a free group, a sufficient condition for Γ and Γ0 to have the same critical exponent is that Γ / Γ0 is amenable.
相似文献
90.