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131.
In this paper, we give a polytopal estimate of Mirkovi?–Vilonen polytopes lying in a Demazure crystal in terms of Minkowski sums of extremal Mirkovi?–Vilonen polytopes. As an immediate consequence of this result, we provide a necessary (but not sufficient) polytopal condition for a Mirkovi?–Vilonen polytope to lie in a Demazure crystal. 相似文献
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134.
Fujiko Iwasaki Seui Kakuma Satoshi Yoshida Shin Murata Masanori Yasui 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):515-516
Abstract The deformation electron-density distributions of 6a-thia-1,3,4,6-tetraazapentalene derivatives (I, II) and bis(phenylthio)dibenzothiophene (III) were investigated by the X-ray diffraction method. For I and II, a structure around the hypervalent S-N bonds is a trigonal bipyramid with equatorial sp2 hybrid of S-C bond and lone-pair electrons and apical polarized S-N bonds. In 111 lone-pair electron densities are observed perpendicular to the thiophene ring and the C-S-C sulfide planes. 相似文献
135.
Polymerization of acrolein(AL) in the presence of imidazole(Im) has been investigated in tetrahydrofuran or methanol below room temperature. The polymers obtained, white or pale yellow powders, were found to be composed of vinyl polymer with one Im group attached and having an aldehyde side chain, of which 70–80 mole % of the aldehyde revealed bridge structure. The number-average molecular weight (M n) of these polymers was determined to be in the range of 317 to 691. The rate of polmerization Rp was expressed by the equation, R + k[Im] [AL]2. The addition of water or dimethyl sulfoxide accelerated the polymerization reaction, while the presence of benzaldehyde or N,N'-dimethylformamide decreased Rp. The structure of addition products in the initial polymerization step was confirmed by IR and NMR spectra, and the observations of polymerization system was carried out by UV and NMR spectra. The polymerization mechanisms were discussed on the basis of these results. 相似文献
136.
Toyoji Kakuchi Toshifumi Satoh Junji Mata Satoshi Umeda Hisaho Hashimoto Kazuaki Yokota 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):325-336
Abstract The cyclopolymerizations of 1,2:5,6-dianhydro-3,4-di-O-pentyl-D-mannitol (1b) and 1,2:5,6-dianhydro-3,4-di-O-decyl-D-mannitol (1c) were carried out using BF3OEt2 and t-BuOK. All the resulting polymers consisted of cyclic constitutional units, i.e., the extent of cyclization was 100%. The polymer structures for the polymerization with t-BuOK were (1→6)-2,5-anhydro-3,4-di-O-pentyl-D-glucitol (2b) and (1→6)-2,5-anhydro-3,4-di-O-decyl-D-glucitol (2c), whereas those with BF3O-decyl2 comprised 2,5-anhydro-D-glucitols as major units along with other cyclic ones. These polymers were soluble in n-hexane, CHCl3, and THF, but insoluble in water, which differs from the amphiphilic solubility of (1→6)-2,5-anhydro-3,4-di-O-methyl-D-glucitol (2a). The cation-binding properties of 2b and 2c were examined using alkali-metal picrates in order to compare them with those of 2a. The extraction yields for each cation decreased in the order of 2c < 2b < 2a. Every polymer exhibited a similar cation-binding selectivity in the order Cs+ > Rb+ > K+ ? Na+ > Li+. The ratio of K+ and Na+, K+/Na+, was 4.6 for 2a, 5.1 for 2b, and 7.1 for 2c in the increasing order 2a < 2b > 2c. 相似文献
137.
Luise Oemisch Kai-Uwe Goss Satoshi Endo 《Analytical and bioanalytical chemistry》2013,405(8):2567-2574
Experimental determination of oil-water partition coefficients often poses difficulties associated with emulsion formation. The aim of this work was to find an appropriate technique for determination of oil–water partition coefficients of polar, nonvolatile compounds. Two different methods were tested. The first method used a “silicone membrane equilibrator.” For the second method, solid-phase microextraction (SPME) fibers with a polyacrylate (PA) coating were used as a passive sampler. With both methods, oil–water partition coefficients for 14 compounds with polar functional groups were determined at 37 °C with good repeatability (standard deviation 0.11 log units or lower). The partition coefficients determined with the silicone membrane equilibrator method ranged from 0.50 to 3.49 log units. The oil–water partition coefficients obtained with the PA-SPME passive sampling approach were significantly higher than those obtained with the silicone membrane equilibrator method for nine of 14 compounds. The differences were up to 0.39 log units (i.e., a factor of 2.5). Additional experiments suggested that this difference occurred because the sorption properties of the PA fibers used were influenced by the surrounding phase, e.g., through swelling of the polymer phase. Therefore, the SPME passive sampling method using PA fibers seems to be less reliable, whereas the silicone membrane equilibrator method was found to be a convenient technique for the determination of oil–water partitioning. 相似文献
138.
Yutaka Kubota Yuri Kaneda Kazuhiro Haraguchi Mirei Mizuno Hiroshi Abe Satoshi Shuto Takayuki Hamasaki Masanori Baba Hiromichi Tanaka 《Tetrahedron》2013
The key glycosyl donor for the target molecule 12 was prepared by two-step sequences; (1) acetalization of tert-butyldimethylsilyloxyacetaldehyde with 3-bromopropanediol, (2) DBN-initiated β-elimination of the resulting 2-(tert-butyldimethylsilyloxy)methyl-4-bromomethyl-1,3-dioxolane 11. Electrophilic glycosidation between 12 and silylated pyrimidine nucleobase proceeded efficiently to provide a mixture of β- and α-anomers of the respective glycosides 14 and 15. Tin radical-mediated reduction of the bromomethyl functional group of 14 and 15 gave protected 4′-C-methyl-dioxorane uracil- 16 and thymine nucleoside 17. The respective cytosine nucleoside 18 was synthesized from 16. De-silylation of 4′-methyl-1′,3′-dioxolane pyrimidine nucleosides 16–18 gave the target molecules. Evaluation of the anti-HIV-1 activity of the β- and α-anomers of the novel 4′-C-methyl-1′,3′-dioxolane nucleosides 22β,α–24β,α revealed that none of the nucleoside derivatives possess anti-viral activity against HIV-1 and show cytotoxicity against MT-4 cells at 100 μM. 相似文献
139.
Eric M. Yezdimer Tomohiro Umemoto Hiroshi Yamada Satoshi Makino Ikuo Tooyama 《Applied biochemistry and biotechnology》2013,170(5):1138-1150
The potential utility of an imaging agent for the detection of hepatic copper was investigated in a Wilson’s disease animal model. Solid-phase peptide synthesis was used to construct an imaging agent which consisted of a copper-binding moiety, taken from the prion protein, and a gamma ray-emitting indium radiolabel. Long–Evans Cinnamon (LEC) rats were used for the Wilson’s disease animal model. Our evaluation methodology consisted of administering the indium-labeled agent to both LEC and genetically healthy Long–Evans (LE) cohorts via a tail vein injection and following the pharmacokinetics with single-photon emission computed tomography (SPECT) over the course of an hour. The animals were then sacrificed and their livers necropsied. An additional control agent, lacking the copper-binding moiety, was used to gauge whether any change in the hepatic uptake might be caused by other physiological differences between the two animal models. LEC rats injected with the indium-labeled agent had roughly double the amount of hepatic radioactivity as compared to the healthy control animals. The control agent, without the copper-binding moiety, displayed a hepatic signal similar to that of the control LE animals. Additional intraperitoneal spiking with CuSO4 in C57BL/6 mice also found that the pharmacokinetics of the indium-labeled, prion-based imaging agent is profoundly altered by exposure to in vivo pools of extracellular copper. The described SPECT application with this compound represented a significant improvement over a previous MRI application using the same base peptide sequence. 相似文献
140.
Satoshi Kaneco Kensuke Hayashi Hideyuki Katsumata Tohru Suzuki 《International journal of environmental analytical chemistry》2013,93(13):1381-1388
A preconcentration method by adsorption of cadmium on a niobium wire was developed for the environmental waters, followed by electrothermal atomic absorption spectrometry with a tungsten tube atomizer. After the preconcentration, the niobium wire was directly inserted into the tungsten tube atomizer. In the preconcentration (adsorption) process of cadmium, the optimal immersing time was 60?s. The effects of large amounts of concomitants on the preconcentration of cadmium were evaluated. When 103–104 fold excess of matrix elements existed in aqueous solution at pH 4 and 9, the cadmium response was profoundly affected by the matrix elements. However, the cadmium absorption signal was not significantly influenced at pH 7. Therefore, pH 7 was selected for the application into the real environmental samples. Under the optimal conditions, the detection limit (3S/N) for cadmium by the niobium wire preconcentration method was 7.0?pg?mL?1 and the relative standard deviation was 6.8%. The method with preconcentration on a niobium wire was applied to the determination of cadmium in water and proved to be sensitive, simple and convenient. Because this preconcentration method can be utilized in the in situ treatment of trace cadmium in environmental water samples, it was unnecessary to carry the water samples to the analytical work place. The technique was shown to be useful for the determination of cadmium in environmental water samples at 0.1–1?µg?L?1 levels. 相似文献