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991.
Osamu Shimomura Toshihiko Sato Ikuyoshi Tomita Masato Suzuki Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(14):2813-2819
A monomer having dibenzothiophene moiety, 2-vinyldibenzothiophene (1), was prepared by the Ni-catalyzed cross-coupling reaction of vinyl bromide with the Grignard reagent of 2-bromodibenzothiophene. The radical homopolymerization of 1 and the copolymerization with styrene were carried out at 60°C in toluene (1.0M) for 20 h using AIBN (5 mol %) as an initiator to obtain the corresponding polymers in high yields. Thermal analyses of the copolymers showed that both 10% weight loss and glass transition temperatures increase when increasing the content of 1 unit. The monomer reactivity ratio was evaluated as r1 = 2.55 (1) and r2 = 0.16 (styrene). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2813–2819, 1997 相似文献
992.
Fumio Sanda Toru Abe Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(13):2619-2629
Syntheses and radical polymerizations of several (meth)acrylamides having L -amino acid moieties were examined. The monomers were prepared by the reactions of L -amino acid ester hydrochlorides with (meth)acryloyl chloride in the presence of triethylamine in satisfactory yields. Radical polymerizations of the monomers were carried out in the presence of AIBN (1 mol %) in bulk and in several solvents to afford the corresponding polymers in satisfactory yield. The glass transition temperatures and specific rotations of the polymers depended on the substituents of the L -amino acid moieties. Nearly the same specific rotations were observed for the monomers and the model compounds of the polymer units, N-pivaloyl amino acid methyl esters. On the contrary, the specific rotations of the polymers shifted to the negative direction in ca. 30°. The interaction between the polymer side chains might affect the changes in the specific rotations from monomers to polymers. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2619–2629, 1997 相似文献
993.
994.
Joël Jacob Katrin Geßler Daniel Hoffmann Haruyo Sanbe Kyoko Koizumi Steven M. Smith Takeshi Takaha Wolfram Saenger 《Angewandte Chemie (International ed. in English)》1998,37(5):605-609
The cavity of the larger molecule has less space for guests! Unlike the structure of the smaller annular cyclodextrins, that of the higher homologues of cycloamyloses (CAs) with more than ten glucose units contains a 90° kink between adjacent glucose residues within one half of the molecule and a 180° band flip between adjacent units in different halves (see depicted section of the CA14 structure) to yield butterfly-shaped structures with narrow, groovelike cavities. 相似文献
995.
Naotoshi Nakashima Takeshi Tokunaga Yuko Nonaka Takashi Nakanishi Hiroto Murakami Takamasa Sagara 《Angewandte Chemie (International ed. in English)》1998,37(19):2671-2673
Two reversible one-electron transfers are observed for an electrode device made from C60 and an artificial lipid (see schematic drawing). Cyclic voltammetric studies reveal that the redox couples are unchanged even after 50 cycles, thus indicating that the C60 radical monoanion and the C60 dianion generated in aqueous solution are very stable. 相似文献
996.
Fumio Sanda Emiko Koyama Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1998,36(12):1981-1986
Synthesis and radical polymerization of a novel optically active methacrylate, (S)–2–tert–butoxycarbonylamino–3–phenylpropyl methacrylate (MA–F–BOC), were examined. MA–F–BOC was synthesized from methacrylic acid and N–protected (L)–phenylalaninol. Radical polymerization of MA–F–BOC quantitatively afforded the corresponding polymethacrylate with a relatively high molecular weight. Radical copolymerizations of MA–F–BOC were carried out with styrene and acrylamide to afford the copolymers. Radical polymerization of MA–F–BOC in the presence of n–butanethiol afforded the oligomers, whose degrees of polymerizations were 3.3–8.0. The BOC group was completely cloven with HBr to afford the corresponding optically active polymeric amine quantitatively. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 1981–1986, 1998 相似文献
997.
998.
Shuichi Matsumura Takeshi Okamoto Keisuke Tsukada Kazunobu Toshima 《Macromolecular rapid communications》1998,19(6):295-298
Oxiranes, such as glycidyl phenyl ether (GPE) and benzyl glycidate (BG), were copolymerized with succinic anhydride (SA) by lipase at a temperature between 60 and 80°C to yield the corresponding polyesters bearing carboxyl or phenyl groups. Bulk polymerization, especially at the temperature of 80°C, and preferably using porcine pancreatic lipase gave biodegradable polyesters with a molecular weight greater than 5000. 相似文献
999.
Osamu Shimomura Ikuyoshi Tomita Takeshi Endo 《Macromolecular rapid communications》1998,19(9):493-497
The cationic initiation activity of derivatives of S-methylsulfonium salts has been evaluated in the cationic polymerization of glycidyl phenyl ether ( 1 ). These initiators are soluble in 1 and capable of initiating the cationic polymerization of 1 on heating, except for methyltetrahydrothiophenium tetrafluoroborate ( 6 ) (r.t. −160°C). Among them, methyldiphenylsulfonium tetrafluoroborate ( 4 ) shows moderate thermal latency, that is the polymerization of 1 occurs efficiently at 160°C but not below 80°C. 相似文献
1000.
1,9-Bis(methylthio)dibenzothiophene (1a) was treated with one equivalent of bromine and pyridine in the presence of l-menthol and then with aqueous sodium hydroxide to give optically active 1-(methylsulfinyl)-9-(methylthio)dibenzothiophene (2a) enriched by the S isomer (ee: 57%). The configuration of optically pure sulfoxide (2a) was determined by X-ray crystallographic analysis to be the S configuration at the sulfinyl sulfur atom. On the other hand, 1-(methyl-l-menthoxysulfonio)-9-(methylthio)dibenzothiophene tetrafluoroborate (4a) was isolated as an intermediate of this asymmetric oxidation in an optically pure form, as yellow crystals. The absolute configuration of this sulfonium salt (4a) was verified by X-ray crystallographic analysis as the R configuration. Optically pure sulfonium salt (4a) also gave partially optically active sulfoxide (2a) with net inversion on its hydrolysis. It was suggested that the hydrolysis reaction of the sulfonium salt (4a) accordingly proceeds, not only via a sulfurane having a simple SN2 type of geometry but also by a front side attack ofhydroxide anion, with respect to the l-menthoxy group, on sulfur, and the sequential elimination of the l-menthoxy group from the tetracoordinated intermediate. © 1996 John Wiley & Sons, Inc. 相似文献