全文获取类型
收费全文 | 3146篇 |
免费 | 0篇 |
专业分类
化学 | 1451篇 |
晶体学 | 12篇 |
力学 | 317篇 |
数学 | 526篇 |
物理学 | 840篇 |
出版年
2021年 | 8篇 |
2019年 | 8篇 |
2014年 | 10篇 |
2013年 | 9篇 |
2008年 | 14篇 |
2006年 | 60篇 |
2004年 | 17篇 |
2003年 | 22篇 |
2002年 | 53篇 |
2001年 | 57篇 |
2000年 | 69篇 |
1999年 | 53篇 |
1998年 | 64篇 |
1997年 | 61篇 |
1996年 | 48篇 |
1995年 | 55篇 |
1994年 | 51篇 |
1993年 | 61篇 |
1992年 | 96篇 |
1991年 | 111篇 |
1990年 | 89篇 |
1989年 | 89篇 |
1988年 | 61篇 |
1987年 | 72篇 |
1986年 | 90篇 |
1985年 | 104篇 |
1984年 | 86篇 |
1983年 | 96篇 |
1982年 | 85篇 |
1981年 | 80篇 |
1980年 | 76篇 |
1979年 | 90篇 |
1978年 | 93篇 |
1977年 | 97篇 |
1976年 | 116篇 |
1975年 | 109篇 |
1974年 | 88篇 |
1973年 | 103篇 |
1972年 | 81篇 |
1971年 | 103篇 |
1970年 | 120篇 |
1969年 | 72篇 |
1968年 | 46篇 |
1967年 | 26篇 |
1966年 | 18篇 |
1965年 | 19篇 |
1964年 | 14篇 |
1963年 | 15篇 |
1962年 | 9篇 |
1961年 | 10篇 |
排序方式: 共有3146条查询结果,搜索用时 15 毫秒
61.
62.
63.
Synthesis and nitration of NH- and N-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines
T. N. Borisova I. A. Stazharova A. É. Aliev N. S. Prostakov A. V. Varlamov 《Chemistry of Heterocyclic Compounds》1991,27(10):1105-1109
It has been shown that the most efficient catalysts for the synthesis of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine from 1,2,5-trimethylpyridin-4-one and acetylene under Trofimov conditions are rubidium and potassium hydroxides. Use of Triton B or a mixture of trimethylbenzylammonium chloride with rubidium hydroxide as catalyst gives O-alkylated oxime. Their configurations and conformations were established through separation of the individual isomers of 1-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines. Acetyl nitrate nitration of the cis isomer of this compound gave the 2- and 3-nitro derivatives. Similar nitration of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine gave the 2-nitro-7-hydroxy derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1375–1380, October, 1991. 相似文献
64.
É. Ya. Lukevits A. E. Pestunovich M. G. Voronkov T. M. Kupch 《Chemistry of Heterocyclic Compounds》1972,8(4):442-444
It was found that the hydrosilylation of N-allylpyrrolidine and N-allylpiperidlne by trialkylsilanes, triethoxysilane, and 3H-heptamethyltrisiloxane in the presence of H2PtCl6 · 6H2O proceeds to form -adducts.Communication XXXII from the series Nitrogen-Containing Organosilicon Compounds. See [1] for communication XXXI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 485–487, April, 1972. 相似文献
65.
66.
A decaying weakly ionized helium plasma [ne=(0.2–1.1)·1011 cm–3, p=(40–70) mm Hg] was studied experimentally. It is shown that the experimental time dependences of the intensities of atomic lines and molecular bands in the afterglow phase can be explained if the vibrational kinetics of He2
+ ions is included in the analysis. Analysis of the measurements shows that for ne 1011 cm–3 and Na 1018 cm–3 deexcitation of He2
+ ions occurs primarily as a result of inelastic collisions with helium atoms. Based on the experimental data, an approximate value was obtained for the rate constants of the vibrational relaxation of molecular helium ions 10–16 cm3/sec. These results are used for making a qualitative analysis of the distribution of He2
+ ions over the vibrational states in the discharge phase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 88–96, November, 1986. 相似文献
67.
68.
M. Yu. Lidak R. A. Paégle V. É. Straume D. É. Shnore Yu. P. Shvachkin 《Chemistry of Heterocyclic Compounds》1971,7(3):372-376
The synthesis of peptides which include a DL--(N1-uracilyl)--alanine (DL-willardiine) residue as an N-terminal or C-terminal group was investigated, dipeptides of DL-willardiine with glycine and L-tyrosine were obtained, and DL-willardiyl-DL-willardiine was synthesized; the latter is the simplest representative of the family of monotonic homopeptides which contain, as a repeating side substituent, a natural nucleic base capable of participation in intermolecular interactions of the complementary type.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 404–408, March, 1971. 相似文献
69.
É. A. Karakhanov S. Kh. Sharipova M. I. Rozhkova E. A. Viktorova 《Chemistry of Heterocyclic Compounds》1978,14(1):15-16
It is shown that the principal pathway in the reaction of benzofuran with a solution of lithium in hexametapol is opening of the furan ring of benzofuran to give a dilithium derivative. Mono- and dialkylation products are formed when the reaction mixture is treated with alkylating agents. It was established by the use of alkylating agents with different degrees of hardness that the oxygen atom is a softer polarizable center than the sp-hybridized carbanion center.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 22–23, January, 1978. 相似文献
70.
A method for calculating the asymmetry parameters of molecules based on Avnir’s CSM approach combined with the “dissymmetry
function” method is suggested. The performance of the approach is demonstrated on various geometrical models — high-symmetry
antiprisms of S10 and D5 symmetry groups, helices, and molecular objects. It is shown that the MCSM method unambiguously determines the symmetry element
or estimates the degree of asymmetry for molecules from different structural classes.
A. V. Bogatskii Physiocochemical Institute, Ukrainian Academy of Sciences. Odessa State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 547–552, May–June, 1998. 相似文献