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861.
Yuya Yamashita Hisashi Matsui Koichi Ito 《Journal of polymer science. Part A, Polymer chemistry》1972,10(12):3577-3587
Bischloroformates of hydroxy-terminated poly(tetramethylene glycol) (PTG) and polystyrene (PSt) were prepared and used as the initiators for the anionic polymerization of α-pyrrolidone and ε-caprolactam in bulk at 30°C and 80°C, respectively. Initiation efficiency was sufficiently high to give well-defined nylon–PTG(or PSt)–nylon block copolymers. Both the yield and the viscosity of the block copolymer increased with polymerization time up to 50% conversion of the lactam. 相似文献
862.
Hisashi Morikawa Yoshinori Uwamino Toshio Ishizuka 《Fresenius' Journal of Analytical Chemistry》1990,336(3):210-214
Summary Rare earth elements (REEs) in yttrium oxide were determined by secondary ion mass spectrometry (SIMS) with high sensitivity. The calibration graph approach was employed with chemically prepared standards. Molecular ion interferences derived from the matrix components which limit the superior sensitivity of SIMS were successfully suppressed by an energy filtering technique. The detection limits of the elements ranged from 0.02 to 0.2 g·g-1. 相似文献
863.
A new methanodithiomethano-bridged dibenzotrithionin (1) has been synthesized. The electrochemical oxidation of 1 and its analogous compound was studied by cyclic voltammetry. A new type of the sulfur extrusion of 1 was found in the reaction of 1 with concd H2SO4 or 2 equiv of NOPF6 and in its photochemical reaction. 相似文献
864.
Mitsuru Ueda Hisashi Hazome Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1976,14(5):1127-1135
Novel oxime-containing polyamides have been prepared by the ring-opening polyaddition of combinations of two benzobis[1,2]oxazinediones, 4,6-diphenylbenzo[1,2-d:5,4-d′]bis[1,2]oxazine-1,9-dione and 4,9-diphenylbenzo[1,2-d:4,5-d′]bis[1,2]oxazine-1,6-dione, with two aliphatic diamines in a polar aprotic solvent such as N-methyl-2-pyrrolidone. The polymerization was almost completed within a day at room temperature. These polymers had inherent viscosities in the range of 0.12–0.38 and were soluble in a wide range of solvents, including formic acid and hot m-cresol, as well as a number of polar aprotic solvents. All the polymers softened at a temperature ranging from 165 to 185°C. Thermal characterization of the polyamides by TGA and DTA showed polymer decomposition temperatures of about 240°C in air. 相似文献
865.
Hirata KS Kajita T Kifune T Kihara K Nakahata M Nakamura K Ohara S Oyama Y Sato N Takita M Totsuka Y Yaginuma Y Mori M Suzuki A Takahashi K Tanimori T Yamada M Koshiba M Suda T Miyano K Miyata H Takei H Kaneyuki K Nagashima Y Suzuki Y Beier EW Feldscher LR Frank ED Frati W Kim SB Mann AK Newcomer FM Van Berg R Zhang W Fukugita M 《Physical review letters》1988,61(23):2653-2656
866.
Hagiwara H Kobayashi K Miya S Hoshi T Suzuki T Ando M Okamoto T Kobayashi M Yamamoto I Ohtsubo S Kato M Uda H 《The Journal of organic chemistry》2002,67(17):5969-5976
The phytotoxins solanapyrones D (1) and E (2) have been synthesized from the decalone prepared by the domino Michael reaction of the kinetic enolate of optically pure acetylcyclohexene with methyl crotonate. The decalone was transformed into a solanapyrone core by equilibration into thermodynamically stable trans-decalone (11), dehydroxylation, and dehydration. Condensation of a methyl acetoacetate equivalent followed by cyclization installed a pyrone moiety. Introduction of a formyl or hydroxymethyl unit into the pyrone ring via Pummerer related reactions furnished solanapyrones D (1) and E (2). 相似文献
867.
Ultrafast analysis of oligosaccharides on microchip with light-emitting diode confocal fluorescence detection 总被引:2,自引:0,他引:2
We have developed a new method for the high-speed separation and high-sensitivity detection of complex oligosaccharides based on microchip electrophoresis (nu-CE) with light-emitting diode (LED) confocal fluorescence detection. Oligosaccharides labeled with 8-aminopyrene-1,3,6-trisulfonate (APTS) were found to strongly adsorb to the surface of polymethylmethacrylate (PMMA) microchips. Accordingly, three classes of major dynamic coating additives were systematically investigated, and cellulose derivatives were found to specifically suppress such adsorption and allow high-performance separation on PMMA chips. Additive concentration, buffer pH and applied field strength were found to be key factors in the high-performance separation& of APTS-labeled oligosaccharides on PMMA chips. Under optimal conditions, 15 oligosaccharides in dextrin hydrolysate can be separated within 45 s with an electrophoretic separation efficiency of over 400 000 theoretical plates per meter. The relative standard deviation (RSD) values of migration times of fourteen oligosaccharides were less than 0.50% between six different channels, and the detection limit for APTS-labeled glucose was about 1.98 x 10(-8) mol/L or 8.61 amol with a signal-to-noise ratio (S/N) of 3. The high speed, high efficiency and high sensitivity of this micro-CE-based method indicate that it can be widely applied to analysis of complex oligosaccharides. 相似文献
868.
Yoshiki Sohrin Kenji Isshiki Eiichiro Nakayama Sorin Kihara Masakazu Matsui 《Analytica chimica acta》1989
The simultaneous determination of tungsten and molybdenum in sea water is based on preconcentration by column extraction with 7-(1-vinyl-3,3,5,5-tetramethylhexyl)-8-quinolinol (Kelex- 100) resin, and measurement of the polarographic catalytic currents obtained in a solution of chlorate, benzilic acid and 2-methyl-8-quinolinol. When the concentration factor is 50, the detection limits are 2.4 pM for tungsten and 17 pM for molybdenum (for a signal-to-noise ratio of 3). The precision of the determination is ca. 10% for 67 pM tungsten and ca. 5% for 106 nM molybdenum in sea water (n=4). Results for sea water and other natural waters are presented. 相似文献
869.
Morikawa T Matsuda H Nishida N Ohgushi T Yoshikawa M 《Chemical & pharmaceutical bulletin》2004,52(11):1387-1390
Three new aromatics glycosides, hyuganosides II, IIIa, and IIIb, were isolated from a Japanese folk medicine, the roots of Angelica furcijuga KITAGAWA. The structures of the new glycosides were determined on the basis of chemical and physicochemical evidence. 相似文献
870.
Kuroda-Sowa T Liu SQ Yamazaki Y Munakata M Maekawa M Suenaga Y Konaka H Nakagawa H 《Inorganic chemistry》2005,44(6):1686-1692
Reaction of [2.2]paracyclophane with silver(I) heptafluorobutyrate (AgC3F7CO2) has isolated three novel networks: [Ag4(pcp)(C3F7CO2)4] x pyrene (1), [Ag4(pcp)(C3F7CO2)4] x phen (phen = phenanthrene) (2), and [Ag4(pcp)(C3F7CO2)4] x fluorene (3), and an intercalation compound [Ag4(pcp)(C3F7CO2)4] x 2benzene (4). All the four complexes exhibit two-dimensional (2D) sheet structures in which AgC3F7CO2 form an infinite chain and pcp acts as linkage. 1, 2, and 3 show 2D flat sheets with cavities in which guest molecules are situated, whereas 4 exhibits 2D zigzag layers between which guest benzene molecules are intercalated. Pcp shows mu-di-eta1-eta2 coordination mode in 1, mu-tetra-eta1 coordination mode in 2 and 3, and mu-tetra-eta2 coordination mode in 4. The reversible guest exchanges were observed between complex 1, 2, or 3 and intercalation compound 4. It is unprecedented for metal-organic inclusion complexes that the guest exchange occurs where the guest is the solute molecule. Furthermore, 4 can release the guest, and the original framework was completely recovered after reincorporation of benzene. It should be noted that 4 can incorporate pyrene, phen, and fluorene to give 1, 2, and 3, respectively, after desorption. 相似文献