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41.
We have developed a Cd2+ fluorescent chemosensor with high selectivity as well as sensitivity by tethering a 4,7-bis(2-hydroxyethyl)-9-hydroxy-1,4,7-triazanonyl chelator to anthracene. This sensor features the ability to discriminate Cd2+ from Zn2+ to a high degree (KdZn/KdCd = 560) in a pH 7.2 buffer. 相似文献
42.
K. Imai S. Higashidate A. Nishitani Y. Tsukamoto M. Ishibashi J. Shoda T. Osuga 《Analytica chimica acta》1989
Oxo-steroids and oxo-bile acid ethyl esters were derivatized with 5-N,N-dimethylamino-naphthalene-1-sulphonohydrazide (DNS-hydrazine) to DNS-hydrazone in the presence of hydrochloric acid in ethanol or trifluoroacetic acid in benzene, purified by high-performance gel-permeation chromatography, separated on an ODS column with an eluent containing tetrahydrofuran and detected via a peroxyoxalate chemiluminescence reaction using bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate (TDPO). Sensitive detection (femtomole level) of each oxo-steroid which appeared as a single peak was achieved. The procedure for the isolation of oxo-bile acids developed for GC-MS allowed the detection by this system of an unusual oxo-bile acid, 7α-hydroxy-3-oxo-5β-cholanic acid, at the nanomole l?1 level in urine from a patient with cholestatic liver disease. 相似文献
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K Yoshino K Goto T Kohno T Morita G Tsukamoto 《Chemical & pharmaceutical bulletin》1990,38(3):676-680
Various asymmetric or cyclic ester derivatives of the phosphonic acid moiety in the calcium antagonist fostedil (KB-944) were synthesized. The coronary vasodilator activity of these compounds was assessed by Langendorff's method. Among them, the ethyl isopropyl ester 12 showed the most potent activity, which was comparable to that of fostedil. 相似文献
45.
Anjima H Tsukamoto S Mori H Mine M Klobukowski M Miyoshi E 《Journal of computational chemistry》2007,28(15):2424-2430
We developed new model core potentials (MCPs) for s-block elements from Na to Ra, in which the outer core (n-1)s and (n-1)p electrons are treated explicitly together with the ns electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate ionization potentials of atoms and very good spectroscopic constants of ionic and covalent molecules. The results obtained with the new MCPs are very close to the ones obtained using the all-electron correlation consistent basis sets of Dunning. 相似文献
46.
Koki Tsukamoto Toshio Watanabe Umpei Nagashima Yutaka Akiyama 《Journal of Molecular Structure》2005,732(1-3):87-98
A reaction mechanism of a nitric oxide reductase, cytochrome P450nor (P450nor) from Fusarium oxysporum, was clarified by using Density functional theory and Hartree–Fock calculations. In this reaction mechanism, molecular orbital (MO) analysis revealed that the NO ligand dissociates from the heme iron immediately after one-electron reduction by NADH, and MO energy analysis revealed that NADH acts as a one-electron reducer, not as a two-electron reducer, and that NADH has a pivotal role different from other one-electron reducers. The role of NADH is to act as a double one-electron donor (i.e. one-electron transfer occurring twice) and to combine with the NO− molecule by charge recombination reaction. Our quantum chemical calculations indicated that all reactions occurring in the heme pocket are too fast to become rate-limiting. Therefore, the rate-limiting steps in the proposed reaction mechanism are the process of capturing NO and NADH into the heme pocket and the process of expelling a product generated in the heme pocket. Kinetics of these processes was discussed based on large-amplitude vibration, which helps capturing and expelling processes in a widely opened heme pocket of P450nor. The reaction mechanism proposed here well explains published experimental data. 相似文献
47.
For any positive integer D, we construct a minimal dynamical system with mean dimension equal to D/2 that cannot be embedded into (([0, 1] D )?, shift). 相似文献
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Tsukamoto D Ikeda M Shiraishi Y Hara T Ichikuni N Tanaka S Hirai T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(35):9816-9824
Semiconductor TiO2 particles loaded with WO3 (WO3/TiO2), synthesized by impregnation of tungstic acid followed by calcination, were used for photocatalytic oxidation of alcohols in water with molecular oxygen under irradiation at λ>350 nm. The WO3/TiO2 catalysts promote selective oxidation of alcohols to aldehydes and show higher catalytic activity than pure TiO2. In particular, a catalyst loading 7.6 wt % WO3 led to higher aldehyde selectivity than previously reported photocatalytic systems. The high aldehyde selectivity arises because subsequent photocatalytic decomposition of the formed aldehyde is suppressed on the catalyst. The TiO2 surface of the catalyst, which is active for oxidation, is partially coated by the WO3 layer, which leads to a decrease in the amount of formed aldehyde adsorbed on the TiO2 surface. This suppresses subsequent decomposition of the aldehyde on the TiO2 surface and results in high aldehyde selectivity. The WO3/TiO2 catalyst can selectively oxidize various aromatic alcohols and is reusable without loss of catalytic activity or selectivity. 相似文献