全文获取类型
收费全文 | 266篇 |
免费 | 2篇 |
专业分类
化学 | 148篇 |
晶体学 | 2篇 |
力学 | 11篇 |
数学 | 40篇 |
物理学 | 67篇 |
出版年
2021年 | 2篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2011年 | 12篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 13篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 6篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1935年 | 2篇 |
1931年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 31 毫秒
61.
Nils O. Nilsen Lars Skattebøl Mark S. Baird Sheila R. Buxton Paul D. Slowey 《Tetrahedron letters》1984,25(27):2887-2890
Reaction of the dibromides (5) and (10) with methyl lithium in ether leads to products derived by 1,3-dehalogenation, (6) and (11), whereas (15) and (16) undergo 1,1-dehalogenation and rearrangement to allenes, (17) and (18). 相似文献
62.
Abe K Abt I Ahn CJ Akagi T Allen NJ Ash WW Aston D Baird KG Baltay C Band HR Barakat MB Baranko G Bardon O Barklow T Bazarko AO Ben-David R Benvenuti AC Bienz T Bilei GM Bisello D Blaylock G Bogart JR Bolton T Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Busza W Calcaterra A Caldwell DO Calloway D Camanzi B Carpinelli M Cassell R Castaldi R Castro A Cavalli-Sforza M Church E Cohn HO Coller JA Cook V Cotton R Cowan RF Coyne DG D'Oliveira A Damerell CJ Daoudi M 《Physical review D: Particles and fields》1996,53(3):1023-1038
63.
Abe K Abt I Ahn CJ Akagi T Allen NJ Ash WW Aston D Baird KG Baltay C Band HR Barakat MB Baranko G Bardon O Barklow T Bazarko AO Ben-David R Benvenuti AC Bienz T Bilei GM Bisello D Blaylock G Bogart JR Bolton T Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Busza W Calcaterra A Caldwell DO Calloway D Camanzi B Carpinelli M Cassell R Castaldi R Castro A Cavalli-Sforza M Church E Cohn HO Coller JA Cook V Cotton R Cowan RF Coyne DG D'Oliveira A Damerell CJ Daoudi M 《Physical review letters》1995,75(23):4173-4177
64.
65.
Abe K Abt I Ahn CJ Akagi T Ash WW Aston D Bacchetta N Baird KG Baltay C Band HR Barakat MB Baranko G Bardon O Barklow T Bazarko AO Ben-David R Benvenuti AC Bienz T Bilei GM Bisello D Blaylock G Bogart JR Bolton T Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Busza W Calcaterra A Caldwell DO Calloway D Camanzi B Carpinelli M Cassell R Castaldi R Castro A Cavalli-Sforza M Church E Cohn HO Coller JA Cook V Cotton R Cowan RF Coyne DG D'Oliveira A Damerell CJ Dasu S 《Physical review letters》1995,74(15):2895-2899
66.
Reaction of 2,2′-bipyridine-6-carboxaldehyde with the appropriate aliphatic diamine in MeOH and subsequent reduction with NaBH4 gives the new, potentially hexadentate, ligands N,N′-bis(2,2′-bipyridin-6-ylmethyl)ethane-1,2-diamine (bmet), N,N′-bis(2,2′-bipyridin-6-ylmethyl)propane-1,3-diamine (bmpp) and N,N′-bis(2,2′-bipyridin-6-ylmethyl)hexane-1,6-diamine (bmhx). The syntheses and characterisation of these ligands are reported; the ligands are isolated as the hydrochloride salts, with purification effected by either recrystallisation or cation exchange chromatography. [Co(bmet)](ClO4)3 · H2O is obtained on reaction of bmet · 4.25HCl · 2.5H2O with Na3[Co(O2CO)3] · 3H2O, and X-ray structural analysis shows this to have a pair of very short Co–N bonds. The synthesis and characterisation of the first coordination complex containing 6-(aminomethyl)-2,2′-bipyridine (amb) is also described. 相似文献
67.
The compounds (π-C6H6)Ru(R)Cl(PPh3) (RCH3, C6H5), (π-C6H6)RuCl(π-C3H5) and [(π-C6H6)Ru(π-C5H5)]Cl are described. The 31P NMR spectra of a series of tertiary phosphine complexes of the π-benzeneruthenium system are also reported. 相似文献
68.
The concept of ionic character in and bond systems is considered in the light of recent definitions of orbital electronegativity [6, 14].
We wish to acknowledge financial support from the National Research Council of Canada. One of us (N.C.B.) thanks the council for the award of a studentship. 相似文献
Zusammenfassung Das Konzept des ionischen Charakters in und Bindungen wird im Lichte neuerer Definitionen von Orbitalelektronegativitäten diskutiert.
Résumé Le caractère ionique des liaisons et est discuté en tenant compte des définitions récentes de l'électronégativité des orbitales.
We wish to acknowledge financial support from the National Research Council of Canada. One of us (N.C.B.) thanks the council for the award of a studentship. 相似文献
69.
Ryan D Madder Chu-Young Kim Pooja P Chandra Jeffrey B Doyon Teaster A Baird Carol A Fierke David W Christianson Judith G Voet Ahamindra Jain 《The Journal of organic chemistry》2002,67(2):582-584
QSAR has been used to elucidate the origin of the hydrophobicity and binding affinity of a small library of fluoroaromatic inhibitors of F131V carbonic anhydrase II. Our analysis predicted the presence of a twisted amide conformation for several bound inhibitors, which we confirmed crystallographically. We also determined that the hydrophobicity of the inhibitors as a whole results from the fragment hydrophobicities of their fluorobenzyl rings, corrected for field effects and the presence of an intramolecular F.H contact in solution. The loss of this interaction on binding to the enzyme makes the affinity sensitive to the same terms, but with the opposite dependence on the F.H contact. In the case of the four inhibitors bound as twisted amides, this F.H contact must be retained to some extent in the bound state in order for their affinities to be consistent with our QSAR analysis of the entire set of 17 molecules. 相似文献
70.
J. Lowe S.H. Chew J.M. Nelson C.E. Waltham G.J. Pyle G.T.A. Squier S. Baird C.J. Batty P. Sharman P. Bird A.S. Clough K.R. Parker 《Nuclear Physics B》1982,209(1):16-28
The reaction K?p → Λγ, produced by K? stopping in a liquid hydrogen target, has been studied using a NaI(Tl) gamma-ray spectrometer. The branching ratio is based on 1355 events assigned to this branch. This is in conflict with a previous experiment, but agrees with one of the two published calculations, when recent values for the coupling constants and scattering amplitudes are used. 相似文献