全文获取类型
收费全文 | 3036篇 |
免费 | 34篇 |
国内免费 | 3篇 |
专业分类
化学 | 2101篇 |
晶体学 | 55篇 |
力学 | 91篇 |
综合类 | 3篇 |
数学 | 222篇 |
物理学 | 601篇 |
出版年
2022年 | 51篇 |
2021年 | 63篇 |
2020年 | 59篇 |
2019年 | 78篇 |
2018年 | 97篇 |
2017年 | 86篇 |
2016年 | 90篇 |
2015年 | 72篇 |
2014年 | 86篇 |
2013年 | 140篇 |
2012年 | 122篇 |
2011年 | 158篇 |
2010年 | 103篇 |
2009年 | 125篇 |
2008年 | 133篇 |
2007年 | 151篇 |
2006年 | 108篇 |
2005年 | 97篇 |
2004年 | 87篇 |
2003年 | 112篇 |
2002年 | 102篇 |
2001年 | 77篇 |
2000年 | 52篇 |
1999年 | 30篇 |
1998年 | 29篇 |
1997年 | 24篇 |
1996年 | 30篇 |
1995年 | 28篇 |
1994年 | 26篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 25篇 |
1990年 | 27篇 |
1988年 | 18篇 |
1987年 | 28篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 27篇 |
1983年 | 20篇 |
1981年 | 17篇 |
1978年 | 26篇 |
1977年 | 28篇 |
1975年 | 24篇 |
1974年 | 21篇 |
1973年 | 24篇 |
1972年 | 21篇 |
1971年 | 20篇 |
1970年 | 22篇 |
1968年 | 24篇 |
1967年 | 25篇 |
排序方式: 共有3073条查询结果,搜索用时 15 毫秒
11.
12.
O. G. Yarosh Z. G. Ivanova T. D. Burnashova M. G. Voronkov 《Russian Chemical Bulletin》1984,33(11):2394-2396
Conclusions The reaction of magnesium bromide derivatives of di- and triethynylsilanes with dimethylethynylfluorosilane gave 1,2-disubstituted silylacetylenes containing ethynyl and vinyl groups at the silicon atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2614–2616, November, 1984. 相似文献
13.
The paper discusses the structural changes of some Cu(II) and Ni(II) complexes during the heating and their influence upon the decomposition stoichiometry. The influence of the interactions inside of coordination polyhedra, bonding and stereochemical properties of the counter ions or molecules are discussed in this connection as well. The expressive influence of the plasticity or rigidity of the Cu(II) and Ni(II) coordination polyhedra, respectively, is emphasized.
Zusammenfassung Es werden wÄrmebedingte StrukturverÄnderungen einiger Cu(II) bzw. Ni(II)-Komplexe sowie deren Einflu\ auf die Stöchiometrie der Zersetzung beschrieben. In diesem Zusammenhang wird auch ebenso der Einflu\ von Wechselwirkungen innerhalb des Koordinationspolyeders sowie von Bindungs- und stereochemischen Eigenschaften der Gegenionen oder -moleküle beleuchtet. Es wird der ausdrucksvolle Einflu\ der PlastizitÄt und HÄrte von Cu(II)- und Ni(II)-Koordinationspolyedern hervorgehoben.相似文献
14.
G. F. Chernenko K. I. Demenkova E. E. Ivanova É. N. Shmidt 《Chemistry of Natural Compounds》1990,26(5):548-551
A study of the chemical composition of a petroleum ether extract of the bark of Yeddo spruce growing in Khabarovsk Territory has shown that the neutral fraction of the extract contained waxes, glycerides, diterpenoids — epimanool, cis- and trans-abienols, and phyllocladenol, and triterpenoids — the epimeric 3α-and 3β-methoxy-21-hydroxy-Δ14-serratenes and a ketone which has been ascribed the structure of 21-keto-3β-methoxy-Δ14-serratene. 相似文献
15.
V. V. Berentsveig Zaki A. Hasan P. B. Fabrichnyi T. M. Ivanova A. P. Rudenko 《Reaction Kinetics and Catalysis Letters》1980,15(2):239-243
The state of mixed iron-tin oxide catalysts with a variable ratio of their metallic components has been studied by Mössbauer and ESCA spectroscopy. The results are compared with the activity of these catalysts in cyclohexane oxidation.
- . .相似文献
16.
Summary Methyl -nitrocrotonate has been synthesized by the condensation of methyl nitroacetate with acetaldehyde, acetylation of the methyl -nitro--hydroxybutyrate, and subsequent deacetylation of the resulting product. 相似文献
17.
18.
R. K. Alekseenko L. S. Ivanova D. I. Shvets 《Theoretical and Experimental Chemistry》1991,26(6):694-697
In order to establish the interrelation between the electronic characteristics of carbons that are manifested in the EPR spectra and their ability to adsorb complex gold and silver ions, the EPR spectra of carbon adsorbents from phenol-formaldehyde resins of various nature, unactivated and activated under various conditions, and the adsorption of [Au(CN)2]– and [Ag(CN)2]– from cyanide solutions on these same adsorbents were investigated. A parallel relation was observed between the amount of paramagnetic centers on carbon and its adsorption capacity and selectivity in relation to these anions.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 6, pp. 742–745, November–December, 1990. 相似文献
19.
Sheinin V. B. Ivanova Yu. B. Berezin B. D. 《Russian Journal of General Chemistry》2002,72(7):1128-1131
The association equilibrium of porphyrinium ions of mesoporphyrin IX dimethyl ester (H2MP) with iodide ions in acetonitrile was studied by spectropotentiometric titration. Two associates were revealed: (H4MP2
+)(I-) and (H4MP2
+)(I-)2; the electronic absorption spectra of these species were measured, and their formation constants were determined. 相似文献
20.
E. A. Amelina I. V. Videnskii N. I. Ivanova A. M. Parfenova V. V. Pelekh N. V. Altukhova E. D. Shchukin 《Colloid Journal》2001,63(5):527-531
The effect of cationic surfactants (cetyltrimethylammonium bromide and tetrabutylammonium iodide) and cationic polyelectrolyte polyethylenimine on the coefficient of friction and adhesion force p(during shear and tensile testing, respectively) at the point contacts between the individual fibers of cellulose, viscose, and cellulose acetate was studied. The comparison of these data with the results of -potential and adsorption measurements enabled us to relate the nonmonotonic dependence of parameters and pon the surfactant concentration to the changes in electrosurface properties and the hydrophilicity or hydrophobicity of the fibers. The specific free energy of interaction U[mJ/m2] was estimated for cellulose acetate fibers. 相似文献