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931.
Kazuhiko Takai Tooru Kuroda Shigeki Nakatsukasa Koichiro Oshima Hitosi Nozakil 《Tetrahedron letters》1985,26(45):5585-5588
Alkynyl halides are reduced by chromium(II) chloride in DMF to give unisolable alkynylchromium compounds which add selectively to an aldehyde moiety without affecting the coexisting ketone group of the substrate. 相似文献
932.
An amperometric sensor with a single working electrode for simultaneous determination of electro-inactive anions and cations, e.g. SO4(2-), Cl(-), NO3(-), Na(+), NH4(+), K(+), Mg(2+) and Ca(2+), was designed as a detector in ion chromatography. The modification of its working golden electrode was based on the incorporation of dodecyl sulfate into polydiphenylamine by electropolymerization of diphenylamine in the presence of sodium dodecylsulfate. In ion-exclusion/cation-exchange chromatography, a set of well defined peaks of these anions and cations was obtained at the working potential, +1.35 V (vs. saturated calomel electrode) using a citric acid solution as eluent. The common anions and cations in mineral water samples were determined using this ion-chromatographic system with satisfactory results. 相似文献
933.
Toshio ShinoharaMidori A. Arai Kazuhiko WakitaTakayoshi Arai Hiroaki Sasai 《Tetrahedron letters》2003,44(4):711-714
The highly ligand acceleration effect of spiro bis(isoxazoline) ligand (SPRIX) on the Pd(II)-catalyzed intramolecular aminocarbonylation of alkenyl amine derivatives was realized. Furthermore, the chiral Pd(II)-SPRIX catalyst accomplished the first enantioselective intramolecular aminocarbonylation. The reaction of N-(2,2-dimethyl-pent-4-enyl)-p-toluenesulfonamide in the presence of Pd(II)-SPRIX catalyst and p-benzoquinone in methanol under a carbon monoxide atmosphere afforded [4,4-dimethyl-1-(p-toluene-sulfonyl)-pyrrolidin-2-yl]-acetic acid methyl ester in good yield with moderate enantioselectivity. 相似文献
934.
Nobuaki Tanaka Junichi Oike Kazuhiko Shibuya Satoshi Kudoh Munetaka Nakata 《Research on Chemical Intermediates》1998,24(8):893-903
Visible-light-induced oxygen-atom transfer from NO2 to trimethylamine has been investigated in a low-temperature Ar matrix. The bimolecular reaction with the threshold wavelength
of 610 nm is tentatively interpreted by a mechanism to form the intermediate products of (CH3)2NONO and CH3, or the final products of (CH3)2NOCH3 and NO. Further irradiation at shorter wavelength (457.9–514.5 nm) seems to cause the secondary photolysis of (CH3)2NONO into (CH3)2NO and NO, which is followed by the recombination of (CH3)2NO with CH3 coexisting in a cryogenic Ar matrix cage to produce N,N,O-trimethylhydroxylamine, (CH3)2NOCH3. The reaction mechanism proposed is different from those reported for CH3NH2/NO2 and (CH3)2NH/NO2, the reason of which is discussed in comparison of the potential energy surfaces of three amine/NO2 photolytic systems. 相似文献
935.
Bunsuke Umezawa Osamu Hoshino Shohei Sawaki Haruki Sashida Kazuhiko Mori Yoshinori Hamada Katsumi Kotera Yoichi Iitaka 《Tetrahedron》1984,40(10):1783-1790
(±)-α-Lycoran-3,5-dione (14a) was prepared from octahydrophenanthridin-3-one (8b) obtained by two methods starting from 5-aryl-4-nitrocyclohexene (2) and 1-hydroxyl-2-aryl-5-oxo-cyclohexanecarboxylic acid (10), both of which were prepared by the Diels-Alder reaction of 3,4-methylenedioxy - ω - nitrostyrene with butadiene and the Robinson annelation of 3,4-methyl- enedioxy - phenylpyruvic acid (9) with methyl vinyl ketone, respectively, 14a was converted into (±)Δ2-α-lycoren-7-one (22b), which has been transformed into (±)-lycorine (1) by Torssell 相似文献
936.
The development of cocatalysts promoting overall water splitting on (Ga1−x
Zn
x
)(N1−x
O
x
) solid solution photocatalyst is presented. The (Ga1−x
Zn
x
)(N1−x
O
x
) is a stable visible-light-driven photocatalyst for stoichiometric water splitting upon loading with a suitable nanoparticulate
cocatalyst. Loading with a combination of Cr and Rh oxides, Rh2−y
Cr
y
O3, is demonstrated to raise the quantum efficiency of (Ga1−x
Zn
x
)(N1−x
O
x
) for overall water splitting to 2.5% at 420–440 nm. This represents a 10-fold increase in efficiency over the highest efficiency
previously obtained using nanoparticulate RuO2 as a cocatalyst. In addition to the composition, the dispersion and size of cocatalyst nanoparticles are identified as important
factors affecting the degree of enhancement for stoichiometric water splitting.
Kazuhiko Maeda—Research Fellow of the Japan Society for the Promotion of Science (JSPS). 相似文献
937.
Seki T Mochida J Okamoto M Hosoya O Juni K Morimoto K 《Chemical & pharmaceutical bulletin》2003,51(6):734-736
Diffusion coefficients (D) of parabens and steroids in water and 1-octanol were determined by using the chromatographic broadening method at 37 degrees C, and the relationships between the D values and the physicochemical properties of the drugs were discussed. The D values in 1-octanol were lower than those in water because of the higher viscosity of 1-octanol. The D values depend on not only the molecular weight (MW), but also the lipophilicity of the drugs in water and on the ability for hydrogen-bonding in 1-octanol. When the lipophilic index (LI), calculated from the retention time using in a reverse-phase column, was used as a parameter of drug lipophilicity, the following equation was obtained for D in water (D(w)); log D(w)=-0.215.log MW-0.077.log LI-4.367. When the hydrogen bond index (HI), the logarithm of the ratio of the partition coefficient of the drugs in 1-octanol and cyclohexane, was used as an index of hydrogen-bonding, the following equation was obtained for D in 1-octanol (D(o)); log D(o)=-0.690.log MW-0.074.log HI-4.085. 相似文献
938.
A new coated capillary has been introduced for capillary electrophoretic separation of anions by using a positively charged diazacrown ether with a 12-membered ring. A positive charge spread over the inner capillary surface led to a substantial anodic electroosmotic flow (EOF) over the range of migrating buffer of pH 2-11. Under the optimum conditions of 25 mM phosphate buffer at pH 7, the diazacrown-coated capillary showed a successful simultaneous separation of 7 inorganic anions and 13 aromatic anions (including positional isomers) in less than 15 min. The migration times of the sample anions and EOF marker for consecutive runs on a single column were highly reproducible, giving a relative standard deviation of 1%. Theoretical treatment of the migration behavior clearly demonstrated that ion association between the diazacrown and analyte anions is strongly dependent on the nature of the functional groups of anions (e.g., sulfonate groups > carboxyl groups) and the number of negative charges (e.g., trivalent anions > divalent anions > monovalent anions) on the analyte. 相似文献
939.
The objective of this study was to examine the effects of acetonitrile (AN) on the adsorption behavior of bovine serum albumin (BSA) onto calcium hydroxyapatite [Ca10(PO4)6(OH)2 Ca10, Hap] materials by combining the ultraviolet (UV) and circular dichroism (CD) measurements of BSA solution. The structural change of BSA molecules with addition of AN was investigated by UV and CD spectroscopy measurements prior to studying adsorption behavior of BSA onto Hap. The CD spectra revealed that the fraction of alpha-helical content of BSA is remarkably decreased at AN concentrations above 30 vol.%, while beta-sheet content is increased. On the other hand, the percentages of random coil and turn contents were decreased only slightly. In addition to this secondary structural change of BSA, the UV spectra suggested that the tertiary structure of protein molecules was also changed by the addition of large amounts of AN; BSA molecules associate to form molecular aggregates at [AN]> or =40 vol.%. From the adsorption of BSA onto Hap particles (ca. 30 nm in the particle length) from a water-AN mixed solution, it was revealed that the adsorption behavior of BSA strongly depends on the change of secondary and tertiary structures of BSA by addition of AN. The contraction of BSA molecules at low AN concentrations (10-20 vol.%) gave their small cross-sectional area, providing a large amount of adsorption (n(BSA)), although n(BSA) was decreased above 30 vol.% AN by enlargement of BSA molecules with solvation and unfolding some alpha-helix domains. The n(BSA) values of the systems with AN exhibited a maximum; n(BSA) was increased at a lower BSA concentration region, although it was decreased at a higher BSA concentration due to self-association. Accompanying the change of n(BSA) with AN addition, the maxima of electrophoretic mobility (em) of the Hap particles were observed for the systems with AN, although the em of Hap particles was normally increased and saturated with increase in protein coverage for the native structure on the system without AN. On the other hand, because the aggregated BSA molecules could be cooperatively bound, the adsorption of BSA onto the Hap particles with large size (108 nm in the particle length) was enhanced in the presence of AN. 相似文献
940.
Structure of synthetic calcium hydroxyapatite particles modified with pyrophosphoric acid 总被引:1,自引:0,他引:1
Tanaka H Futaoka M Hino R Kandori K Ishikawa T 《Journal of colloid and interface science》2005,283(2):609-612
Synthetic colloidal calcium hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2): CaHap) was treated with pyrophosphoric acid (H(4)P(2)O(7): PP) in acetone and the materials were characterized by XRD, TEM, FTIR, and N(2) and H(2)O adsorption measurements. XRD patterns and morphology of CaHap particles were essentially not changed by the modification. The additional amount of PO(4) of CaHap was increased with an increase of PP concentration and the Ca/P molar ratio of the particles decreased from 1.62 to 0.81. IR results indicated that the isolated surface POH band developed with increasing the PP concentration up to 6.0 mmol dm(-3) by the reaction of isolated surface POH groups of CaHap and pyrophosphoric acids. Above 10.2 mmol dm(-3), a hydrogen-bonding surface POH band appeared at 2913 cm(-1) and enlarged with increasing the PP concentration, while the isolated surface POH band was weakened. The results of N(2) and H(2)O adsorption measurements revealed that the modified particles aggregated compared to the unmodified ones, which would be due to the formation of hydrogen-bonding surface POH groups among the particles. 相似文献