全文获取类型
收费全文 | 8847篇 |
免费 | 224篇 |
国内免费 | 22篇 |
专业分类
化学 | 5862篇 |
晶体学 | 40篇 |
力学 | 134篇 |
数学 | 1603篇 |
物理学 | 1454篇 |
出版年
2021年 | 88篇 |
2020年 | 78篇 |
2019年 | 85篇 |
2018年 | 67篇 |
2016年 | 181篇 |
2015年 | 139篇 |
2014年 | 176篇 |
2013年 | 282篇 |
2012年 | 308篇 |
2011年 | 351篇 |
2010年 | 224篇 |
2009年 | 218篇 |
2008年 | 320篇 |
2007年 | 311篇 |
2006年 | 303篇 |
2005年 | 253篇 |
2004年 | 277篇 |
2003年 | 222篇 |
2002年 | 228篇 |
2001年 | 151篇 |
2000年 | 189篇 |
1999年 | 141篇 |
1998年 | 141篇 |
1997年 | 97篇 |
1996年 | 106篇 |
1995年 | 151篇 |
1994年 | 135篇 |
1993年 | 112篇 |
1992年 | 117篇 |
1991年 | 117篇 |
1990年 | 99篇 |
1989年 | 133篇 |
1988年 | 130篇 |
1987年 | 110篇 |
1986年 | 111篇 |
1985年 | 159篇 |
1984年 | 122篇 |
1983年 | 133篇 |
1982年 | 143篇 |
1981年 | 118篇 |
1980年 | 128篇 |
1979年 | 127篇 |
1978年 | 108篇 |
1977年 | 111篇 |
1976年 | 91篇 |
1975年 | 79篇 |
1974年 | 86篇 |
1973年 | 88篇 |
1972年 | 58篇 |
1971年 | 74篇 |
排序方式: 共有9093条查询结果,搜索用时 15 毫秒
1.
Clemens G. Raab Georg Regensburger Jamal Hossein Poor 《Journal of Pure and Applied Algebra》2021,225(5):106564
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials. 相似文献
2.
Karolina Kula Agnieszka Kcka-Zych Agnieszka apczuk-Krygier Zbigniew Wzorek Anna K. Nowak Radomir Jasiski 《Molecules (Basel, Switzerland)》2021,26(5)
The present paper is a continuation of comprehensive study regarding to synthesis and properties of pyrazoles and their derivatives. In its framework an experimental and theoretical studies of thermal decomposition of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline were performed. It was found, that the decompositions of the mentioned pyrazoline system in the solution and at the melted state proceed via completely different molecular mechanisms. These mechanisms have been explained in the framework of the Molecular Electron Density Theory (MEDT) with the computational level of B3LYP/6-31G(d). A Bonding Evolution Theory (BET) examination of dehydrochlorination of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline permits elucidation of the molecular mechanism. It was found, that on the contrary for most known HCl extrusion processes in solution, this reaction is realised via single-step mechanism. 相似文献
3.
Robin F. Weitkamp Beate Neumann Hans‐Georg Stammler Berthold Hoge 《Angewandte Chemie (International ed. in English)》2020,59(14):5494-5499
We report on the first examples of isolated silanol–silanolate anions, obtained by utilizing weakly coordinating phosphazenium counterions. The silanolate anions were synthesized from the recently published phosphazenium hydroxide hydrate salt with siloxanes. The silanol–silanolate anions are postulated intermediates in the hydroxide‐mediated polymerization of aryl and alkyl siloxanes. The silanolate anions are strong nucleophiles because of the weakly coordinating character of the phosphazenium cation, which is perceptible in their activity in polysiloxane depolymerization. 相似文献
4.
5.
6.
7.
Werner Leißner 《Results in Mathematics》1991,20(1-2):530-537
8.
We relate the Schramm–Loewner Evolution processes (SLE) to highest-weight representations of the Virasoro Algebra. The restriction properties of SLE that have been recently derived in [19] play a crucial role. In this setup, various considerations from conformal field theory can be interpreted and reformulated via SLE. This enables one to make a concrete link between the two-dimensional discrete critical systems from statistical physics and conformal field theory. To cite this article: R. Friedrich, W. Werner, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 947–952. 相似文献
9.
10.