全文获取类型
收费全文 | 10173篇 |
免费 | 43篇 |
国内免费 | 3篇 |
专业分类
化学 | 6159篇 |
晶体学 | 124篇 |
力学 | 387篇 |
数学 | 1383篇 |
物理学 | 2166篇 |
出版年
2019年 | 114篇 |
2018年 | 180篇 |
2017年 | 168篇 |
2016年 | 217篇 |
2015年 | 103篇 |
2014年 | 210篇 |
2013年 | 355篇 |
2012年 | 258篇 |
2011年 | 271篇 |
2010年 | 261篇 |
2009年 | 243篇 |
2008年 | 238篇 |
2007年 | 229篇 |
2006年 | 195篇 |
2005年 | 161篇 |
2004年 | 159篇 |
2003年 | 157篇 |
2002年 | 182篇 |
2001年 | 135篇 |
2000年 | 108篇 |
1998年 | 137篇 |
1997年 | 132篇 |
1995年 | 132篇 |
1994年 | 128篇 |
1993年 | 124篇 |
1992年 | 140篇 |
1991年 | 159篇 |
1990年 | 142篇 |
1989年 | 150篇 |
1988年 | 155篇 |
1987年 | 172篇 |
1986年 | 177篇 |
1985年 | 160篇 |
1984年 | 160篇 |
1983年 | 170篇 |
1982年 | 163篇 |
1981年 | 161篇 |
1980年 | 149篇 |
1979年 | 191篇 |
1978年 | 223篇 |
1977年 | 283篇 |
1976年 | 319篇 |
1975年 | 231篇 |
1974年 | 234篇 |
1973年 | 245篇 |
1972年 | 221篇 |
1971年 | 186篇 |
1970年 | 152篇 |
1969年 | 134篇 |
1968年 | 142篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
R. Kh. Dadashev Kh. B. Khokonov D. Z. Elimkhanov Z. I. Bichueva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(7):1181-1183
A surface tension isotherm equation for ternary systems was derived based on general thermodynamic expressions with consideration for the concentration dependence of the molar surface area. Within the experimental errors, the equation describes the properties of ternary systems with smooth surface tension isotherms. 相似文献
102.
Conclusions Both the extent of C2H4 hydropolymerization, initiated by 0.01% CO, on Co zeolites at a temperature below 100°C, and the initiating effect increase symbatically with increase in the ratio of SiO2/Al2O3 in the zeolite in the investigated limits (from 2 to 10).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 894–896, April, 1974. 相似文献
103.
E. M. Sedykh O. A. Lyabusheva A. Kh. Tambiev L. N. Bannykh 《Journal of Analytical Chemistry》2005,60(1):29-33
An approach to studying the elemental composition of cyanobacteria Spirulina platensis and Nostoc commune using a set of complementary analytical methods (ICP-AES, PAAS, and ETAAS) is proposed. The procedures were adapted for the determination of macro- and microelements (Na, K, Mg, Ca, Fe, Mn, Cu, Mo, Zn, B, and Se) in the biomass of cyanobacteria and separated cell fractions (chloroform and water-methanol extracts and precipitates). The conditions for the mineralization of biological materials were optimized for autoclave and microwave sample preparation procedures. The evaporation and atomization of Se and Mo in a graphite furnace in the presence of chloroform and methanol were studied. The use of combined analytical methods and the interpretation of analytical results allow one to draw conclusions about the ability of cyanobacteria to accumulate biologically important microelements (B, Mo, Se, and Zn) and to optimize technological processes for manufacturing biologically active substances.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 35–40.Original Russian Text Copyright © 2005 by Sedykh, Lyabusheva, Tambiev, Bannykh. 相似文献
104.
D. A. Chernova A. Kh. Vorob’ev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(4):575-578
The rotational mobility of a stable fullerene-based nitroxyl radical (fulleropyrrolineoxyl) in toluene was studied. The rotational correlation time of fulleropyrrolineoxyl was found to be about eight times longer than that of 4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The activation energy of the rotational motion of both probes was determined and their hydrodynamic radii estimated. 相似文献
105.
The conformational equilibrium of -(aminoethyl)pyridines has been studied by molecular-mechanics using the geometry optimization. It has been determined that the equilibrium is characterized by the nearly statistical distribution of the ap- and sc-conformers about the
bond. Substitution of the dimethylamino-group for the amino-group results in a slight shift of the equilibrium toward the ap-rotamers. The global minimum in -(ammoniumethyl)pyridines corresponds to the conformation with the +sc-orientation about the central C-C bond and the -sc-orientation (in the case of the dimethylammonium derivatives) about the
bond. In the latter conformation, the
bond of the ammonium group is oriented toward the pyridine cycle. For charged compounds, the regular orthogonal conformation of the aromatic-ring plate is distorted (the vicinal C-C bond becomes eclipsed).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1833–1840, August, 1991.The authors are grateful to P. P. Shagidullin and A. Kh. Plyamovatyi for their interest in this work and for fruitful discussions. 相似文献
106.
R. Ziyaev K. Ikramov Kh. A. Kadyrov A. Abdusamatov 《Chemistry of Natural Compounds》1991,27(4):516-517
Tashkent Agricultural Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 587–588, July–August, 1991. 相似文献
107.
108.
Kh. Kh. Mukhsinov 《Journal of Mathematical Sciences》1985,29(3):1370-1371
The author corrects errors which occurred in his papers published in J. Sov. Math.,23, No. 2 (1983). A new bound of the inhomogeneous minimum Mn is given: forn?200 $$M_n \leqslant 2^{ - \tfrac{n}{2}} \left( {4.4455 + \tfrac{{1.3545}}{{n - 1}}} \right).$$ This is stronger than Davenport's result forn?200. 相似文献
109.
O. E. Nasakin A. N. Lyshchikov P. M. Lukin A. Kh. Bulai 《Chemistry of Heterocyclic Compounds》1994,30(3):312-316
The reaction of 1,1,2,2-tetracyanoethane with 1-R,3-R,5-R-2,4-diazapenta-1, 4-dienes leads to 2,5-disubstituted 3,3,4,4-tetracyanopyrrolidines. The conditions for the acylation of the last were selected.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 353–358, March, 1994. 相似文献
110.
O. E. Nasakin A. N. Lyshchikov P. M. Lukin A. Kh. Bulai V. A. Tafeenko P. A. Sharbatyan 《Chemistry of Heterocyclic Compounds》1991,27(11):1212-1217
2,5-Substituted 3,3,4,4-tetracyanopyrrolidines react with primary alcohols in the presence of an excess of a base or with the base itself. 2-(N-Arylideneamino)-5-alkoxy-3,4-dicyanopyrroles are formed as a result of the reactions with alcohols, and 2,5-diamino-1-R-3,4-dicyanopyrroles are formed as the result of the reaction with primary aliphatic amines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1502–1507, November, 1991. 相似文献