全文获取类型
收费全文 | 99119篇 |
免费 | 5415篇 |
国内免费 | 4629篇 |
专业分类
化学 | 56258篇 |
晶体学 | 1331篇 |
力学 | 5583篇 |
综合类 | 322篇 |
数学 | 11834篇 |
物理学 | 33835篇 |
出版年
2023年 | 749篇 |
2022年 | 1709篇 |
2021年 | 2115篇 |
2020年 | 2310篇 |
2019年 | 2507篇 |
2018年 | 2892篇 |
2017年 | 2823篇 |
2016年 | 3486篇 |
2015年 | 2409篇 |
2014年 | 3477篇 |
2013年 | 4919篇 |
2012年 | 5056篇 |
2011年 | 5355篇 |
2010年 | 4249篇 |
2009年 | 4255篇 |
2008年 | 4453篇 |
2007年 | 4174篇 |
2006年 | 3804篇 |
2005年 | 3377篇 |
2004年 | 3037篇 |
2003年 | 2711篇 |
2002年 | 2828篇 |
2001年 | 2547篇 |
2000年 | 1988篇 |
1999年 | 1605篇 |
1998年 | 1535篇 |
1997年 | 1329篇 |
1996年 | 1293篇 |
1995年 | 1077篇 |
1994年 | 1160篇 |
1993年 | 1097篇 |
1992年 | 1069篇 |
1991年 | 1126篇 |
1990年 | 1120篇 |
1989年 | 1041篇 |
1988年 | 918篇 |
1987年 | 916篇 |
1986年 | 883篇 |
1985年 | 925篇 |
1984年 | 915篇 |
1983年 | 822篇 |
1982年 | 800篇 |
1979年 | 801篇 |
1978年 | 812篇 |
1977年 | 806篇 |
1976年 | 919篇 |
1975年 | 812篇 |
1974年 | 844篇 |
1973年 | 847篇 |
1972年 | 752篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
The simplest gauge theory of an elastic-plastic medium is considered in this paper that takes account of just translational plasticity. The equations of motion for such a model turn out to be linear and permit the normal modes spectrum of a medium to be obtained. Taking account of plasticity results in a cardinal transformation of the elastic branches of the spectrum and the appearance of a group of plasma oscillations of a dislocation gas.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 64–68, June, 1990. 相似文献
162.
Yu. N. Sidorenko 《Journal of Mathematical Sciences》1989,46(5):2097-2104
A hierarchy of Poisson Hamiltonian structures connected with an elliptic spectral problem is constructed. Generating operators connected with the Landau-Lifshits equations and asymmetric chiral 0(3)-field are found.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 161, pp. 76–87, 1987.The author is profoundly grateful to P. P. Kulish, A. G. Reiman, and M. A. Semenov-Tyan-Shanskii for interest in the present paper and helpful comments. 相似文献
163.
Ya. Yu. Nikitin 《Journal of Mathematical Sciences》1988,43(6):2833-2838
The rough asymptotic behavior of the probability of large deviations is found for Watson-Darling goodness-of-fit tests, which are centered versions of Kolomogorov-Smirnov statistics. Their Bahadur effectiveness is calculated and conditions for local asymptotic optimality for the alternative of translation are studied.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 158, pp. 138–145, 1987. 相似文献
164.
The production rate of light photinos in radiative pion decay \(\pi ^0 \to \gamma \tilde \gamma \tilde \gamma\) is calculated. Experimental constraints on masses and mass splittings of scalar quarks imply the following upper bound on the decay rate \(BR(\pi ^0 \to \gamma \tilde \gamma \tilde \gamma ) \lesssim 10^{ - 16}\) . 相似文献
165.
S. V. Litvinenko Yu. M. Volovenko F. S. Babichev 《Chemistry of Heterocyclic Compounds》1992,28(11):1307-1311
A new method for the synthesis of pseudo-cross-conjugated mesomeric betainic heterocyclic compounds with an angular nitrogen atom has been developed consisting in the reaction of 1,4-dielectrophile — -carbethoxy-2-(3-chloro)quinoxalylacetonitrile with azoles. Experimental regularities have been studied and a reaction mechanism has been proposed including the stage of formation of an ylide from a quaternary azolium salt. A pseudo-crossconjugated mesomeric betainic heterocyclic compound containing a thiazole ring compound has been synthesized for the first time.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1528–1533, November, 1992. 相似文献
166.
Yu. A. Yuzhelevskii E. G. Kagan V. N. Frolov A. L. Klebanskii 《Chemistry of Heterocyclic Compounds》1970,4(1):24-28
The influence of the number of 3, 3, 3-trifluoropropyl(methyl)siloxane links (/) in the cyclotetrasiloxanes mD4-m, where D represents the dimethylsiloxane link and m=0–4, on the rearrangement of these compounds in acetone solution under the action of sodium siloxanolate has been studied. The rearrangement takes place with the formation of a linear polysiloxane the degradation of which yields, in addition to the initial ring, cyclosiloxanes with a different structure. The rate of rearrangement of mD4-m and of the formation of a linear polysiloxane rises with an increase in m from 0 to 3. The equilibrium concentration of the linear polysiloxane formed from mD4-m is inversely proportional to m. Results have been obtained on the kinetics of the formation of the cyclosiloxanes mDn, where m=0–5, n=0–5, and m+n=3–6, in the rearrangement of the rings D3, 2D2, 3D, and 4. The reactivity of the siloxane links rises in the sequence (CH3)2Si-O-Si(CH3)2 < (CF3CH2CH2)-(CH3) Si-O-Si(CH3)2 <(CF3CH2CH2) (CH3)Si-O-Si(CH3) (CH2CH2CF3) . Because of the negative inductive effect transferred through the siloxane links, the 3, 3, 3-trifluoropropyl groups strongly activate the siloxane ring with respect to nucleophiiic reagents.For part I, see [3]. 相似文献
167.
N. S. Prostakov N. M. Mikhailova Yu. M. Talanov 《Chemistry of Heterocyclic Compounds》1970,6(10):1266-1268
The position of the pyridine ring is arylated by reaction of 2,5-dimethyl-4-phenylpyridine with phenyllithium and p-tolyllithium. Destructive oxidation of the diaryl-substituted pyridines primarily affects the pyridine ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1359–1361, October, 1970. 相似文献
168.
169.
170.
Journal of Structural Chemistry - The main features of the changes produced by ions in water may be summarized as follows. The influence of ions on the structure of the “free” water... 相似文献