全文获取类型
收费全文 | 107780篇 |
免费 | 6900篇 |
国内免费 | 5742篇 |
专业分类
化学 | 62614篇 |
晶体学 | 1442篇 |
力学 | 6169篇 |
综合类 | 386篇 |
数学 | 13080篇 |
物理学 | 36731篇 |
出版年
2023年 | 923篇 |
2022年 | 1794篇 |
2021年 | 2309篇 |
2020年 | 2672篇 |
2019年 | 2852篇 |
2018年 | 3187篇 |
2017年 | 3118篇 |
2016年 | 3897篇 |
2015年 | 2786篇 |
2014年 | 3928篇 |
2013年 | 5572篇 |
2012年 | 5794篇 |
2011年 | 6230篇 |
2010年 | 4844篇 |
2009年 | 4805篇 |
2008年 | 5139篇 |
2007年 | 4742篇 |
2006年 | 4325篇 |
2005年 | 3760篇 |
2004年 | 3370篇 |
2003年 | 2960篇 |
2002年 | 3106篇 |
2001年 | 2736篇 |
2000年 | 2179篇 |
1999年 | 1839篇 |
1998年 | 1706篇 |
1997年 | 1452篇 |
1996年 | 1429篇 |
1995年 | 1207篇 |
1994年 | 1249篇 |
1993年 | 1197篇 |
1992年 | 1147篇 |
1991年 | 1207篇 |
1990年 | 1192篇 |
1989年 | 1097篇 |
1988年 | 957篇 |
1987年 | 950篇 |
1986年 | 901篇 |
1985年 | 951篇 |
1984年 | 934篇 |
1983年 | 835篇 |
1982年 | 812篇 |
1979年 | 804篇 |
1978年 | 817篇 |
1977年 | 807篇 |
1976年 | 922篇 |
1975年 | 815篇 |
1974年 | 844篇 |
1973年 | 849篇 |
1972年 | 754篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
991.
A. S. Romakhin I. M. Zaripov Yu. G. Budnikova Yu. M. Kargin E. V. Nikitin A. P. Tomilov Yu. A. Ignat'ev 《Russian Chemical Bulletin》1992,41(6):1036-1040
The mechanism of the electrosynthesis of phosphate esters from white phosphorus was investigated. It was shown that the reaction takes place by two paths, i.e., monomeric (with the participation of dissolved phosphorus) and polymeric (with the participation of phosphorus on the surface of an emulsion drop). It was established that in an alcohol solution of tetraethylammonium iodide the main part of the final product is formed through an intermediate polymeric compound. It was noticed that by studying the dynamics of the accumulation of the dissolved product during electrolysis it is possible to trace the mechanism of reaction of the phosphorus at the individual stages of the process.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420028 Kazan'. V. I. Ul'yanov-Lenin Kazan' State University, 420028 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1328–1333, June, 1992. 相似文献
992.
R. Yu. Kerimov 《International Applied Mechanics》1991,27(1):61-66
Azerbaidzhan Economic Institute, Baku. Translated from Prikladnaya Mekhanika, Vol. 27, No. 1, pp. 71–77, January, 1991. 相似文献
993.
Two polyester concretes with diabase and marble fillers and aggregates are used as examples to illustrate the possibility of using a structural approach to evaluate the creep of the composite in the initial state and after preliminary aging under laboratory conditions for a period of 12–13 yrs. Experimental study of the creep of polymer concrete and its structural components (resin and binder) after preliminary aging at elevated temperatures (60, 90°) established that the change that occurs in viscoelastic compliance with aging conforms to the analogy principle with a reduction function that depends on aging temperature and time.Institute of Polymer Mechanics. Latvian Academy of Sciences Riga, Latvia. Central Laboratory of Physico-chemical Mechanics Sofia. Bulgaria. Translated from Mekhanika Kompozitnykh Materialov, Vol. 32, No. 6, pp. 787–794, November–December, 1996. 相似文献
994.
该文用顺磁离子对其近邻~(13)C核的NMR吸收增宽效应,系统地研究了抗坏血酸在不同溶剂中对金属离子Mn~(2+)、Gd~(3+)的配合行为.在水溶液中,抗坏血酸可通过两种配合方式与Mn~(2+)作用,但与Gd~(3+)的作用只有一种稳定的结构.在水中抗坏血酸对金属的配位活性部位分别是1位羟基氧,3位离解的羟基氧和6位羟基氧.在DMSO中,3位羟基由于H~+对该基团的静电遮蔽而变得对金属离子Mn~(2+)表现为配位惰性,同时6位羟基配位活性较大增强.对Gd~(3+)来说,此时没有优势配位活性部位存在.文章还讨论了抗坏血酸在H_2O-DMSO混合溶剂中的~(13)C NMR谱及在DMSO中NaOH对其~(13)C NMR谱及其与金属络合结构的影响. 相似文献
995.
A. Yu. Khrennikov 《Russian Physics Journal》1992,35(11):1036-1039
A p-adic generalization of the frequency theory of probability is developed. Within the framework of this theory frequency meaning is imparted to probabilities belonging to the field of p-adic numbers. The Bargmann-Fock representation is constructed for the p-adic field theory. A frequency interpretation of quantum states in the Bargmann-Fock representation is proposed. The p-adic generalization is essentially an introduction of new quantum states which are meaningless from the point of view of the standard theory of probability based on Kolmogorov's axiomatics.Moscow Institute of Electronic Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 51–55, November, 1992. 相似文献
996.
The black carbon aerosols are now recognized for their potential impact on climate and the halogenated compounds are thought to be very important in atmospheric chemistry. However, there are very few studies on the interactions between soot aerosols and halogenated compounds. We report the measurement of the uptake of CH3I on soot. The measured uptake coefficient is 0.0103 ± 0.0015 at a total pressure of 2–4 Torr and 298 K. The results suggest that the uptake of CH3I occurs efficiently on soot particles. The present work suggests that heterogeneous loss of CH3I on soot may influence the concentration of CH3I throughout the atmosphere. 相似文献
997.
998.
The fourth-order ordinary differential equation that defines the self-similar solutions of the Kaup—Kupershmidt and Sawada—Kotera
equations is studied. This equation belongs to the class of fourth-order analogues of the Painlevé equations. All the power
and non-power asymptotic forms and expansions near points z = 0, z = ∞ and near an arbitrary point z = z
0 are found by means of power geometry methods. The exponential additions to the solutions of the studied equation are also
determined.
相似文献
999.
1000.