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71.
Rapid PCR in a continuous flow device 总被引:6,自引:0,他引:6
Continuous flow polymerase chain reaction (CFPCR) devices are compact reactors suitable for microfabrication and the rapid amplification of target DNAs. For a given reactor design, the amplification time can be reduced simply by increasing the flow velocity through the isothermal zones of the device; for flow velocities near the design value, the PCR cocktail reaches thermal equilibrium at each zone quickly, so that near ideal temperature profiles can be obtained. However, at high flow velocities there are penalties of an increased pressure drop and a reduced residence time in each temperature zone for the DNA/reagent mixture, that potentially affect amplification efficiency. This study was carried out to evaluate the thermal and biochemical effects of high flow velocities in a spiral, 20 cycle CFPCR device. Finite element analysis (FEA) was used to determine the steady-state temperature distribution along the micro-channel and the temperature of the DNA/reagent mixture in each temperature zone as a function of linear velocity. The critical transition was between the denaturation (95 degrees C) and renaturation (55 degrees C-68 degrees C) zones; above 6 mm s(-1) the fluid in a passively-cooled channel could not be reduced to the desired temperature and the duration of the temperature transition between zones increased with increased velocity. The amplification performance of the CFPCR as a function of linear velocity was assessed using 500 and 997 base pair (bp) fragments from lambda-DNA. Amplifications at velocities ranging from 1 mm s(-1) to 20 mm s(-1) were investigated. The 500 bp fragment could be observed in a total reaction time of 1.7 min (5.2 s cycle(-1)) and the 997 bp fragment could be detected in 3.2 min (9.7 s cycle(-1)). The longer amplification time required for detection of the 997 bp fragment was due to the device being operated at its enzyme kinetic limit (i.e., Taq polymerase deoxynucleotide incorporation rate). 相似文献
72.
73.
K Matsumoto H Miyazaki T Fujii H Amejima H Furukawa M Hashimoto 《Chemical & pharmaceutical bulletin》1989,37(10):2807-2810
The mode of binding of sulfonamides to erythrocyte proteins and possible drug-drug interaction between those compounds in erythrocytes resulting in changes in tissue levels were studied in rats using zonisamide (a novel antiepileptic agent possessing a sulfonamide group), several other sulfonamides and some antiepileptics without a sulfonamide group. In Michaelis-Menten plottings, the sulfonamide was found to be concentrated into erythrocytes in vitro and in vivo in a saturable high-affinity mode and in a linear low-affinity mode at ordinary therapeutic plasma levels through a simple diffusion process. Concentration in erythrocytes was affected by the presence of albumin in the extracellular medium. The cellular sulfonamide was readily replaced by extracellular sulfonamides in vitro. Even in vivo, erythrocyte levels of zonisamide were lowered by administration of other sulfonamides, although the plasma and tissue levels were not significantly changed since the plasma and tissue compartments of zonisamide were large relative to the erythrocyte compartment at ordinary therapeutic dose levels of zonisamide in animals and man. Therefore, disposition of zonisamide was not significantly influenced by other sulfonamides, but it is suggested that drug-drug interaction affecting the tissue levels may occur for a combination of sulfonamides with extremely different affinities for erythrocytes and low therapeutic plasma levels. 相似文献
74.
The kainoid amino acids are biologically important compounds because they show remarkable neuroexcitatory and excitotoxic activities. For exhibiting potent activity, the stereochemical relationship of the substituents on the pyrrolidine ring is crucial. We found simple methods for determining the relative stereochemistry of these compounds on the basis of the (1)H NMR chemical shifts of H-2 and H-4 in D(2)O solution. The signals of H-2 appear at fields higher than 4.2 ppm when the compounds have 2,3-trans stereochemistry whereas, in the 2,3-cis compounds, they appear lower than 4.2 ppm, irrespective of the C-4 substituent. This criterion holds when the solution is in the range of pD 3-8. Moreover, when an epimeric pair at C-2 is available and the spectra are recorded at the same or nearly equal pD, the H-2 chemical shift of the 2,3-trans isomer is higher than that of the corresponding 2,3-cis isomer. Similarly, the relative stereochemistry between C-3 and C-4 can be determined from the chemical shift of H-4. The signals of H-4 of the 3,4-cis isomers appear at lower fields than those of the corresponding 3,4-trans isomers in each pair of C-4 epimers when the spectra are recorded at the same or nearly equal pD. This holds for the compounds bearing an unsaturated substituent at C-4. All these phenomena can be rationalized by the anisotropic effect of the pi-electron system in the C-2 and C-4 substituents. 相似文献
75.
Jun Suzuki Kenjiro Fujimoto Toshiyuki Mori Mamoru Watanabe Yoshio Hasegawa 《Journal of Sol-Gel Science and Technology》2000,19(1-3):775-778
The photocatalytic reduction of nitrogen monoxide (NO) with ethane on the hollandite type catalyst (K2Ga2Sn6O16KGSO) was investigated. Using a closed-gas circulating system equipped with a Q-MASS detector and in-situ diffuse reflectance FT-IR spectroscopy. The reactant gases of NO and 13C2H6 decreased with the increasing irradiation time. In contrast, the N2 yield increased proportionally to the conversion of 13C2H6. Nitrogen oxides such as N2O did not reach their detectable levels. The NO adsorbed on KGSO was found to change to its activated species by UV irradiation. The oxidized products of C2H6 such as CH3CHO increased in proportion to the reaction time. The present results strongly suggest that KGSO has remarkable photocatalytic activity for the reduction of NO with C2H6. 相似文献
76.
Sumitra Tavornvipas Hidetoshi Arima Fumitoshi Hirayama Kaneto Uekama Toshihiro Ishiguro Masahide Oka Kenichi Hamayasu Hitoshi Hashimoto 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):391-394
Some physicochemical and biological properties of a new branched cyclodextrin, 6-O--(4-O--d-glucuronyl)-d-glucosyl--cyclodextrin GUG--CyD) were investigated. Further, theinteraction of GUG--CyD with several drugs was studied by the solubility and spectroscopic methods, and compared with those of parent -CyD and 6-O--maltosyl--CyD(2--CyD).The hemolytic activity of GUG--CyD on rabbit erythrocytes was lower than those of -CyD and 2--CyD. GUG--CyD and 2--CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG--CyD to neutral and acidic drugs was comparable to or slightly smaller than those of -CyD and 2--CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG--CyD showed greater affinity for the basic drugs, compared with -CyD and 2--CyD, owing to the electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus GUG--CyD may be useful as a safe solubilizing agent particularly for basic drugs. 相似文献
77.
The cloud point extraction behaviors of lanthanoids(III) (Ln(III) = La(III), Eu(III) and Lu(III)) with and without di(2-ethylhexyl)phosphoric acid (HDEHP) using Triton X-100 were investigated. It was suggested that the extraction of Ln(III) into the surfactant-rich phase without added chelating agent was caused by the impurities contained in Triton X-100. The extraction percentage more than 91% for all Ln(III) metals was obtained using 3.0 × 10−5 mol dm−3 HDEHP and 2.0% (v/v) Triton X-100. From the equilibrium analysis, it was clarified that Ln(III) was extracted as Ln(DEHP)3 into the surfactant-rich phase. The extraction constant of Ln(III) with HDEHP and 2.0% (v/v) Triton X-100 were also obtained. 相似文献
78.
Koketsu M Choi SY Ishihara H Lim BO Kim H Kim SY 《Chemical & pharmaceutical bulletin》2002,50(12):1594-1596
This study reports depigmenting potency of 1,3-selenazol-4-one derivatives, which would be based upon the finding of direct inhibition to mushroom tyrosinase. 1,3-Selenazol-4-one derivatives exhibited inhibitory effect on dopa oxidase activity of mushroom tyrosinase. In this study, inhibitory effects of six kinds of 1,3-selenazol-4-one derivatives (A, B, C, D, E and F) on mushroom tyrosinase were investigated. Compounds at a concentration of 500 microM exhibited 33.4-62.1% of inhibition on dopa oxidase activity of mushroom tyrosinase. Their inhibitory effects were higher than that of kojic acid (31.7%), a well known tyrosinase inhibitor. 2-(4-Methylphenyl)-1,3-selenazol-4-one (A) exhibited the strongest inhibitory effect among them dose-dependently and in competitive inhibition manner. 相似文献
79.
Reactions of 2-alkynyl arylethynyl selenide 1 with alkyl iodides 3 in the presence of lithium aluminium hydride via allenyl selenoketene 2 afforded cyclobutene 4. Allenyl group of the intermediate allenyl selenoketene 2 was monitored by React IR. 相似文献
80.
A gas chromatographic method has been developed that permits the accurate and specific determination of a new psychotropic agent, PF-257, in plasma. PF-257 is extracted with ethyl acetate from alkaline plasma and, after a clean-up procedure, derivatized with heptafluorobutyric anhydride to form 3-[(5-n-heptafluoropropyl-1,2, 4-oxadiazol-3-yl)methyl]-1,2-benzisoxazole (HOMB). The HOMB is assayed on a gas chromatograph equipped with an electron-capture detector. Accurate determinations of PF-257 are possible in the concentration range from 1-40 ng/ml with a relative standard deviation of 6.8%. The minimum detectable concentration in plasma is 0.1 ng/ml. Plasma levels of PF-257 in rats receiving intravenous or oral dosing (10 mg/kg) were determined. 相似文献