全文获取类型
收费全文 | 716篇 |
免费 | 0篇 |
专业分类
化学 | 670篇 |
力学 | 1篇 |
数学 | 12篇 |
物理学 | 33篇 |
出版年
2017年 | 3篇 |
2016年 | 4篇 |
2013年 | 29篇 |
2012年 | 21篇 |
2011年 | 23篇 |
2010年 | 33篇 |
2009年 | 26篇 |
2008年 | 25篇 |
2007年 | 25篇 |
2006年 | 21篇 |
2005年 | 21篇 |
2004年 | 26篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 26篇 |
2000年 | 14篇 |
1999年 | 25篇 |
1998年 | 26篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 11篇 |
1994年 | 18篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1974年 | 12篇 |
1973年 | 12篇 |
1972年 | 8篇 |
1971年 | 19篇 |
1970年 | 9篇 |
1969年 | 6篇 |
1968年 | 4篇 |
1967年 | 8篇 |
1966年 | 7篇 |
排序方式: 共有716条查询结果,搜索用时 15 毫秒
631.
A. E. Shipov G. K. Genkina P. V. Petrovskii T. A. Mastryukova 《Russian Chemical Bulletin》2005,54(11):2629-2634
Reactions of 2-AlkO-1,3,2-oxazaphosphinanes with alkyl N-haloacetylamino or N-chloromethyl-N-methoxycarbonylamino carboxylates mainly give products with retention (Alk = Me) and opening of the ring (Alk = Et). In aqueous
solution, cyclic products with the N-isopropyl group are only stable, while the rest undergo hydrolysis with cleavage of the P-N bond of the ring. Oxazaphosphinane
analogs of phosphorylacetamide and phosphorylacetohydrazide were synthesized. 相似文献
632.
L. N. Novikova I. V. Shchirina-Eingorn N. A. Ustynyuk P. V. Petrovskii L. I. Denisovich 《Russian Chemical Bulletin》1997,46(5):1007-1009
Oxidation of the cyclohexadienyl complex Fe(η5-C5H5)(1-5-75-6-exo-C5H5-C6H6) (2) by (Ph3C)PF6 (CH2Cl2, from −30 to +20 °C) occurs as two concurrent processes: elimination of an H atom from the cyclohexadienyl ligand and replacement
of an H atom in the cyclopentadienyl ring by a CPh3 fragment. A mixture of cationic complexes [Fe(η5-C5H5) (η6-Ph-C5H5]+ (1+) and [Fe(η5-C5H4CPh3) (η6-Ph-C5H5]+ (4+) (4
+) with PF6
− anions is obtained. Deprotonation of the mixture of 1+ and 4+ complexes under the action of Bu
t
OK inm-xylene followed by boiling of the reaction mixture gives phenylferrocene (7) as the product of η6:η6 haptotropic rearrangement.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, NO. 5, pp. 1045–1047, May, 1997. 相似文献
633.
A. A. Kamyshova A. Z. Kreindlin M. I. Rybinskaya P. V. Petrovskii 《Russian Chemical Bulletin》1999,48(3):581-585
Decamethylmetallocenes Cp*
2M (M=Ru, Os) in the presence, of acids (CF3CO2H, CF3SO3H) give thepprotonation products [Cp*
2MH]+An−. Broad-band UV photolysis of their solutions results in the formation of the salts of onium cations
. A preparative procedure for the synthesis of these salts has been developed. Hydrolysis of the salts gives the carbinol
Cp*MC5Me4CH2OH.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 587–591. March, 1999. 相似文献
634.
A. A. Semioshkin P. V. Petrovskii D. Gabel B. Brellochs V. I. Bregadze 《Russian Chemical Bulletin》1998,47(5):950-955
The sodium salt of [B12H12]2− dianion reacts with carboxylic acid halides to give a mixture of B-acylated product [B12H11COR]2− and an unstable intermediate, the latter undergoing hydrolysis to form [B12H11OH]2−. The ratio of the products formed depends on the nature of the radical R. The reaction mechanism was studied by NMR spectroscopy.
A number of novel [B12H11COR]2− compounds were synthesized; their structures were confirmed by NMR and IR spectral data.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 980–985, May, 1998. 相似文献
635.
Makarova N. N. Volkova L. M. Chizhova N. V. Matukhina E. V. Kaznacheev A. V. Petrovskii P. V. 《Russian Chemical Bulletin》2003,52(11):2397-2405
Representatives of stereoregular phenylcyclotetra(hexa)siloxanes with mesogenic cyanobiphenylyl groups cis-oriented relatively to the siloxane ring have been synthesized for the first time. The ability of the compounds to transit to the liquid-crystalline state was confirmed by the thermooptical, X-ray diffraction, and calorimetric methods. The temperatures and enthalpies of the phase transitions were determined, and their reversibility was shown. The bilayered molecular packing with antiparallel arrangement of molecules is the most probable for the smectic A phase of the cyclosiloxanes studied. Taking into account differences in the optical textures and interlayer distances, we cannot exclude completely the possibility of formation of liquid-crystalline phases of other types. 相似文献
636.
T. O. Krylova G. D. Kolomnikova P. V. Petrovskii Yu. G. Gololobov 《Russian Chemical Bulletin》1994,43(9):1553-1555
The interaction of P-containing zwitter-ions based on ethyl 2-cyanoacrylate with methyl iodide, allyl bromide, -bromoacetophenone, and 1,3-dichloroacetone has been studied. Alkylation occurs at the central carbon atom of the pentade anion.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1641–1643, September, 1994. 相似文献
637.
L. I. Strunkina M. Kh. Minacheva K. A. Lyssenko Z. S. Klemenkova A. Yu. Volkonsky P. V. Petrovskii V. V. Burlakov V. B. Shur 《Russian Chemical Bulletin》2003,52(6):1372-1375
The reaction of the bis(trimethylsilyl)acetylene complex of titanocene Cp2Ti(Me3SiC2SiMe3) with mercury trifluoroacetate (NF3COO)2Hg at 20 °C in a THF medium affords titanocene bis(trifluoroacetate) Cp2Ti(OCOCF3)2 and metallic mercury. The structure of Cp2Ti(OCOCF3)2 was established by the analytical and spectroscopic methods and X-ray diffraction analysis. 相似文献
638.
S. V. Sergeev V. A. Nikanorov S. G. Novikov P. V. Petrovskii D. V. Zverev 《Russian Chemical Bulletin》1996,45(9):2203-2206
The ligand exchange reactions of [(C2H4)2Rh(acac)] in benzene and [(C2H4)2RhCl]2 in CH2Cl2 with 4-methyl-4-trichloromethyl-2,5-cyclohexadiene-1-one occur with 100%exo-stereoselectivity. The similar process with 4-methyl-4-trichloromethyl-1-(4,4-dimethyl-4,6-dioxocyclohexylidene)-2,5-cyclohexadiene (trienedione) is strictlyexo-stereospecific only if [(C2H4)2Rh(acac)] in benzene is used, while in the case of [(C2H4)2RhCl]2 in CH2Cl2, it proceeds with anendo-stereoselectivity of 43%. An explanation for these facts has been suggested that assumes that the metal atom initially attacks the central double bond in the trienedione, which is removed from the area of main steric hindrance. The subsequent metallotropic rearrangement of the resulting ethylene-triene intermediate gives rise to the final 4-coordinated -diene structures.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2320–2323, September, 1996. 相似文献
639.
G. D. Kolomnikova D. Yu. Prikhodchenko S. A. Kuznetsova P. V. Petrovskii L. F. Kasukhin Yu. G. Gololobov 《Russian Chemical Bulletin》1992,41(2):337-341
The vinyl esters of phosphorus acids containing an -chloromethylalkenyl substituent react readily with thiourea to form substituted phosphorylated S-isothiuronium chlorides, capable of being dialkylated to the corresponding internal salts (betaines). An allylic rearrangement was discovered for the first time in the series of substituted S-isopropenylisothiuronium salts. The anticholinesterase and toxicological characteristics of some of the obtained comopunds were measured and compared.For previous communication, see [1].A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 425–430, February, 1992. 相似文献
640.