全文获取类型
收费全文 | 357篇 |
免费 | 2篇 |
专业分类
化学 | 334篇 |
数学 | 3篇 |
物理学 | 22篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 23篇 |
2012年 | 18篇 |
2011年 | 15篇 |
2010年 | 21篇 |
2009年 | 14篇 |
2008年 | 22篇 |
2007年 | 23篇 |
2006年 | 18篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有359条查询结果,搜索用时 250 毫秒
101.
102.
103.
Gumenyuk V. V. Starikova Z. A. Nekrasov Yu. S. Babin V. N. 《Russian Chemical Bulletin》2002,51(10):1894-1899
Ferrocenylmethylation and -ferrocenylethylation of indazole were carried out for the first time. Both reactions afforded two isomers, which were characterized by physical and physicochemical methods, among them by X-ray diffraction analysis. 1-(-Ferrocenylethyl)indazole is thermally more stable than the 2-substituted isomer. Both isomers serve as ferrocenylalkylating agents with respect to s-triazole. 相似文献
104.
The basicity constants of a series of para-substituted tetraphenylporphyrins have been determined by two-phase spectrophotometric titration with pH monitoring in the chloroform-aqueous electrolyte solution system; the pH ranges of prevailing of the dication and the neutral forms of the porphyrins have been estimated. With introducing the donor substituents at the para-position of phenyl fragments of porphyrins, the compound basicity increases. Ionization constant of the pyrrole nitrogen atoms depends on the donor-acceptor properties of the substituents according to the Hammett equation. Basing on the derived dependence, theoretical basicity constants of the para-substituted porphyrins bearing strongly donor groups have been predicted. 相似文献
105.
I. D. Kosenko I. A. Lobanova Z. A. Starikova V. I. Bregadze 《Russian Chemical Bulletin》2013,62(8):1914-1918
New hetero-substituted charge-compensated cobalt bis(1,2-dicarbollide) derivatives were synthesized by the reaction of 8,8′-μ-iodo-3-commo-3-cobalta-bis(1,2-dicarba-closo-dodecaborane) [8,8′-μ-I-3,3′-Co(1,2-C2B9H10)2] with 1,4-thioxane, pyridine N-oxide, and tetrahydropyran. X-ray diffraction studies showed that the 8′-iodo-8-(pyridiniumoxy)eucosahydro-1,1′,2,2′-tetracarba-3-commo-cobalta-closo-tricosaborate molecule has the gauche-conformation (the substituents are turned with respect to each other by 69.2°). The positive charge is predominantly localized on the N(Py) atom. 相似文献
106.
Vorontsova N. V. Rozenberg V. I. Vorontsov E. V. Antonov D. Yu. Starikova Z. A. Bubnov Yu. N. 《Russian Chemical Bulletin》2002,51(8):1483-1490
The nucleophilic addition of butyllithium, phenyllithium, methyllithium, and triallylborane to [2.2]paracyclophane-4,7-quinone (1) proceeded regio- and stereospecifically to give the corresponding cis-4,7-disubstituted 4,7-dihydroxy-4,7-dihydro[2.2]paracyclophanes 2—5 with the endo orientation of the hydroxy groups. The structures of quinone 1 and diols 2, 4, and 5 were established by X-ray diffraction analysis. 相似文献
107.
108.
Yan Z. Voloshin Oleg A. Varzatskii Alexander S. Belov Zoya A. Starikova Alexander V. Dolganov Tatiana V. Magdesieva 《Polyhedron》2008
Direct template macrocyclization of the three dimethylglyoxime molecules on the iron(II) ion and the capping of nonmacrocyclic K3CoDm3 tris-dimethylglyoximate with triethylantimony(V) derivatives led to the formation of triethylantimony-capped iron(II) and cobalt(III) clathrochelates. The complexes obtained have been characterized using elemental analysis, MALDI-TOF mass, IR, UV–Vis, 57Fe Mössbauer and 1H and 13C NMR spectroscopies, and X-ray crystallography. The influence of the nature of an encapsulated metal ion, the capping groups and the chelate fragments on a clathrochelate framework geometry is discussed. The cyclic voltammograms show oxidation and reduction waves assignable to Fe2+/3+ and Co2+/3+ couples of the encapsulated metal ion. 相似文献
109.
Alexander V. Degtyarev Alexander F. Pozharskii Zoya A. Starikova Alexander Filarowski 《Tetrahedron》2008,64(27):6209-6214
Protonated 2,7-bis(trimethylsilyl)- and 2,7-di(hydroxymethyl)-1,8-bis(dimethylamino)naphthalenes have been prepared and studied by a combination of X-ray crystallography at room and low temperatures, IR and NMR spectroscopic techniques in conjunction with quantum-chemical calculations. It was demonstrated that the intramolecular [NHN]+ hydrogen bond in the 2,7-bis(trimethylsilyl) system, being sterically compressed, is the shortest among all known aromatic diamine systems. Nevertheless, as it is evidenced by the primary 1H/2H isotope effect, IR spectra and MP2 calculations, a double minimum potential for the proton motion still exists with a very low barrier estimated to be about 0.7 kcal/mol. An influence of a counter-anion on the NH proton involving the spatially hindered H-bond is also considered. 相似文献
110.