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11.
Sahara R Ichikawa H Mizuseki H Ohno K Kubo H Kawazoe Y 《The Journal of chemical physics》2004,120(19):9297-9301
A Monte Carlo simulation is carried out to study thermodynamic properties of Cu-Au alloys using a face-centered-cubic (fcc) lattice-gas model. To obtain quantitatively accurate results, a Finnis-Sinclair-type potential, which has been widely used for molecular dynamics (MD) simulations, is employed. To overcome some shortcomings of lattice-gas models such as neglecting vibrational entropy, the potential is mapped onto the fcc lattice using the renormalization technique. The renormalized potential gives an improved Cu-Au phase diagram compared to the original MD potential applied directly on the lattice. 相似文献
12.
Chin-Ping Yang Yoshiyuki Oishi Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1989,27(12):3895-3901
Aromatic polyamides (aramids) having pendant t-butyl group were synthesized by the direct polycondensation of 5-t-butylisophthalic acid with various aromatic diamines in N-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. The aramids having inherent viscosities of 0.6–2.4 dL/g were obtained in quantitative yields. These polymers were readily soluble in various solvents such as NMP,N,N-dimethylacetamide, dimethyl sulfoxide, and pyridine, and gave transparent, tough and flexible films by casting from the NMP solutions. The aramids had glass transition temperatures between 250 and 330°C, and started to lose weight around 350°C, with 10% weight loss being recorded at about 450°C in air. 相似文献
13.
Chin-Ping Yang Yoshiyuki Oishi Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1990,28(6):1353-1359
Polyarylates containing a t-butyl pendant group were prepared from 5-t-butylisophthaloyl chloride and various bisphenols through the phase-transfer catalyzed two-phase polycondensation. The polyarylates having inherent viscosities up to 3.1 dL/g were obtained quantitatively. They were readily soluble in various solvents such as chloroform, m-cresol, and pyridine. Coloreless, transparent, and flexible films could be cast from the chloroform solutions of the polymers. The polyarylates had glass transition temperatures between 210 and 320°C, and did not lose weight below 350°C, with 10% weight loss being recorded at 395–450°C in air. 相似文献
14.
Yuasa H Izumi T Mitsuhashi N Kajihara Y Hashimoto H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6478-6490
Hinged di- and trisaccharides incorporating 2,4-diamino-beta-D-xylopyranoside as a hinge unit (Hin) were synthesized. Bridging of the diamino group of Hin by carbonylation or chelation to a metal ion results in a conformational change from (4)C1 to (1)C4, which in turn causes a bending of the oligosaccharides. In this study, the bending abilities of the hinged oligosaccharides were compared, in terms of the reactivities toward carbonylation and chelation. Di- or trisaccharides containing a 6-O-glycosylated mannopyranoside or galactopyranoside at their reducing ends had bending abilities similar to that of the Hin monosaccharide, probably because there were neither attractive nor repulsive interactions between the reducing and nonreducing ends. However, when Hin was attached at O2 of methyl mannopyranoside (Man alphaMe), the bending ability was dependent on the nonreducing sugar and the reaction conditions. Typically, a disaccharide--Hin beta(1,2)Man alphaMe--was difficult to bend under all the tested reaction conditions, and the bent population in the presence of Zn(II) was only 4%. On the other hand, a trisaccharide--Man alpha(1,3)Hin beta(1,2)Man alphaMe--was bent immediately after the addition of Zn(II) or Hg(II), and the bent population reached 75%, much larger than those of all the other hinged trisaccharides ever tested (<40%). This excellent bending ability suggests an attractive interaction between the reducing and nonreducing ends. The extended conformation was recovered by the addition of triethylenetetramine, a metal ion chelator. Reversible, quick, and efficient bending of the hinged trisaccharide was thus achieved. 相似文献
15.
Kitano H Tada S Mori T Takaha K Gemmei-Ide M Tanaka M Fukuda M Yokoyama Y 《Langmuir : the ACS journal of surfaces and colloids》2005,21(25):11932-11940
The structure and hydrogen bonding of water in the vicinity of carboxybetaine homopolymer (poly[1-carboxy-N,N-dimethyl-N-(2'-methacryloyloxyethyl)methanaminium inner salt] (PolyCMB), and a random copolymer of CMB and n-butyl methacrylate, Poly(CMB-r-BMA), with various molecular weights were analyzed in their aqueous solutions and thin film with contours of O-H stretching of Raman and attenuated total reflection infrared (ATR-IR) spectra, respectively. The relative intensity of the collective band (C value) corresponding to a long-range coupling of O-H stretchings of the Raman spectra for aqueous solution of Poly(CMB-r-BMA) was very close to that for pure water, which is in contrast with the smaller C value in aqueous solution of ordinary polyelectrolytes. The number of hydrogen bonds collapsed by the presence of one monomer residue (N(corr) value) of PolyCMB and Poly(CMB-r-BMA) (CMB, 45 mol %) (M(w), 1.14 x 10(4) and 1.78 x 10(4), respectively) could be calculated from the C value. The N(corr) values were much smaller than those for ordinary polyelectrolytes and close to those for nonionic water-soluble polymers such as poly(ethylene glycol) and poly(N-vinylpyrrolidone). Furthermore, a water-insoluble Poly(CMB-r-BMA) with a large BMA content (M(w) = 347 kD, CMB 27 mol %) could be cast as a thin film (thickness, ca. 10 microm) on a ZnSe crystal for the ATR-IR analyses. At an early stage of sorption of water into the Poly(CMB-r-BMA) film, the O-H stretching band of IR spectra for the water incorporated in the film was similar to that for free water, which is in contrast with the drastic change in the O-H stretching band of water incorporated in polymer films such as poly(methyl methacrylate) (PMMA) and poly(n-butyl methacrylate) (PBMA). The theoretical vibrational frequency for water molecules hydrating a betaine molecule calculated by using a density functional method supported the experimental results. The adhesion of human platelets to Poly(CMB-r-BMA) films was much less than that to PMMA and PBMA. With an increase in the content of CMB residue, the number of platelets adhered to the Poly(CMB-r-BMA) film drastically decreased and then gradually increased, probably due to the increase in the roughness of the film surface. These results suggest that the carboxybetaine monomer residues with a zwitterionic structure do not significantly disturb the hydrogen bonding between water molecules in both aqueous solution and thin film systems, resulting in the excellent blood-compatibility of the carboxybetaine polymers. 相似文献
16.
Yoshiyuki Oishi Shoichi Nakata Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1992,30(10):2217-2221
New segmented aromatic poly(ether sulfone)-amide and poly(ether sulfone)-imide copolymers were synthesized by the chain extension of α,w-diamine-terminated poly(ether sulfone) oligomer with both aromatic dicarboxylic acid chlorides and tetracarboxylic dianhydrides, respectively. Crystallization of the poly(ether sulfone)unit was suppressed by the introduction of amide or imide linkage along the polymer backbone, giving amorphous copolymers that were +eadily soluble in various organic solvents. The copolymers had somewhat higher glass transition temperatures than the parent poly(ether sulfone). They afforded transparent and tough films by solution casting. © 1992 John Wiley & Sons, Inc. 相似文献
17.
Akiko Saito Mana Emoto Akira Tanaka Yuki Doi Kazuaki Shoji Yoshiyuki Mizushina Hiroshi Ikawa Hiromi Yoshida Nobuyasu Matsuura Noriyuki Nakajima 《Tetrahedron》2004,60(52):12043-12049
A simple method for the synthesis of procyanidin B3 substituted with a galloyl group at the 3 and 3″ position is described. Condensation of a benzylated catechin-3-O-gallate electrophile with a nucleophile, catechin and catechin-3-O-gallate, proceeded smoothly and stereoselectively to afford the corresponding dimer gallates, procyanidin B3-3-O-gallate and procyanidin B3-3,3″-di-O-gallate, in good yields. Further, their antioxidant activities on UV-induced lipid peroxide formation, DPPH radical scavenging activity and inhibitory activity of DNA polymerase were also investigated. Among three procyanidin B3 congeners (procyanidin B3, 3-O-gallate and 3,3″-di-O-gallate), the 3,3″-di-O-gallate derivative showed the strongest antioxidant and radical scavenging activity. Interestingly, the 3-O-gallate derivative was the strongest inhibitor of mammalian DNA polymerase with IC50 value of 0.26 μM, although it showed the weakest antioxidant and radical scavenging activity. It became apparent that the presence of a galloyl group at the C-3 position in the proanthocyanidin oligomer was very important for biological activity, however, the antioxidant activity of these compounds was not parallel to the DNA polymerase inhibitory activity. 相似文献
18.
Yoshiyuki Masui 《Tetrahedron letters》2004,45(9):1853-1856
The title N-alkoxycarbonyl- or N-aryloxycarbonyl-substituted sulfamides were synthesised in one-pot in efficient yields from chlorosulfonyl isocyanate (CSI), alcohols and aqueous (or dry) amines via the corresponding water-resistant intermediates, carboxysulfamoylammonium salts (Burgess-type reagents), which were generated in situ by the deactivation of the corresponding water-sensitive N-(chlorosulfonyl)carbamates with tertiary amines. 相似文献
19.
Fumiyuki Ozawa Takashi Ito Yoshiyuki Nakamura Akio Yamamoto 《Journal of organometallic chemistry》1979,168(3):375-391
New palladium(0) complexes with a variety of coordinated olefins [Pd(olefin)(PMePh2)2] (II) (olefin = styrene, ethyl methacrylate, methyl methacrylate, methyl acrylate, methacrylonitrile, and dimethyl maleate), were prepared by the reactions of [PdEt2(PMePh2)2] (I) with corresponding olefins in toluene. These complexes were characterized by means of elemental analysis, IR and 1H NMR spectroscopy and the chemical reactions. The dissociation of the coordinated olefin from complex II in solution was confirmed by spectroscopic studies of [Pd(mma)(PMePh2)2] (mma = methyl methacrylate). From the variable temperature NMR study, kinetic parameters for the dissociation process were determined as Ea = 7 kcal/mol, and ΔS3 (293 K) = -30 cal/deg · mol. Some new hydrido complexes, [Pd(H)ClL2] (IV) (L = PMePh2, PEtPh2 and PEt2Ph), were prepared by the reactions of [Pd(olefin)L2] with dry HCl. 相似文献
20.
Yoshizumi Ishikawa Hideyasu Honda Yoshiyuki Sugahara 《Journal of Sol-Gel Science and Technology》2000,19(1-3):365-369
The conversion of tetrakis(diethylamino)titanium (Ti(NEt2)4) into titania via either a combination of hydrolysis (Ti(NEt2)4 : THF : H2O = 1 : 10 : x, x = 2, 4, 10) at ambient conditions and calcination (method A) or hydrolysis in a water-tetrahydrofuran (THF) mixture (Ti(NEt2)4 : THF : H2O = 1 : 10 : 100) at reflux (method B) was investigated. Titanium tertiary butoxide (Ti(O
t
Bu)4) was also used as a substitute for Ti(NEt2)4. The hydrolysis via method A resulted in the formation of amorphous solids containing organics. Thermal analyses showed that the hydrolysis products showed mass losses up to 500°C probably due to the presence of diethylamine (Et2NH) formed via the hydrolysis of Ti(NEt2)4 in the hydrolysis products, while a mass loss of the hydrolysis product from Ti(O
t
Bu)4 was completed up to about 200°C. After calcination at 600°C, anatase or a mixture of anatase and rutile was obtained. The crystallization behavior of the hydrolysis products from Ti(NEt2)4 was different from that of the hydrolysis product from Ti(O
t
Bu)4. The hydrolysis via method B gave only an amorphous material from Ti(NEt2)4, while a crystalline titania (anatase and brookite) formed from Ti(O
t
Bu)4. 相似文献