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951.
952.
对s脉冲电压作用下铜丝水中电爆炸的能量沉积过程进行了实验研究,利用自积分Rogowski线圈和电阻分压器分别测量铜丝电爆炸时的电流和电压。利用测量电压波形确定了熔融起始、熔融结束、汽化起始和击穿时刻点,将铜丝电爆炸划分成熔融、液态和汽化3个阶段。通过数学方法计算了3个阶段和击穿前的沉积总能量。通过实验和计算,分析了电路参数,包括放电电压和回路电感,以及铜丝特性,包括铜丝长度和直径,对铜丝电爆炸过程中3个阶段和击穿前沉积总能量的影响。结果表明:在s脉冲电压作用下,放电电压、回路电感、铜丝长度和直径对熔融阶段能量沉积影响较小,但对液态和汽化阶段能量沉积影响较大,通过调节电路参数提高电流上升速率,可以显著提高汽化和击穿前的沉积能量。 相似文献
953.
《Journal of Coordination Chemistry》2012,65(3):177-180
Abstract The reactivity of 1,3-oxazolidine-2-thione towards II B group metals is considered. Cadmium halides, mercury chloride and bromide react to give coordination compounds, whose stereochemistry is tentatively assigned by their i.r. spectra. Otherwise zinc halides and mercury iodide induce a ring opening. 相似文献
954.
Prof. Dr. Peter Comba Dr. Nina Dovalil Prof. Dr. Lawrence R. Gahan Prof. Dr. Gebhard Haberhauer Prof. Dr. Graeme R. Hanson Dr. Christopher J. Noble Dr. Björn Seibold Dr. Prabha Vadivelu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(9):2578-2590
Two synthetic derivatives of the naturally occurring cyclic pseudooctapeptides patellamide A–F and ascidiacyclamide, that is, H4pat2, H4pat3, as well as their CuII complexes are described. These cyclic peptide derivatives differ from the naturally occurring macrocycles by the variation of the incorporated heterocyclic donor groups and the configuration of the amino acids connecting the heterocycles. The exchange of the oxazoline and thiazole groups by dimethylimidazoles or methyloxazoles leads to more rigid macrocycles, and the changes in the configuration of the side chains leads to significant differences in the folding of the cyclic peptides. These variations allow a detailed study of the various possible structural changes on the chemistry of the CuII complexes formed. The coordination of CuII with these macrocyclic species was monitored by high‐resolution electrospray mass spectrometry (ESI‐MS), spectrophotometric (UV/Vis) and circular dichroic (CD) titrations, and electron paramagnetic resonance (EPR) spectroscopy. Density functional theory (DFT) calculations and molecular mechanics (MM) simulations have been used to model the structures of the CuII complexes and provide a detailed understanding of their geometric preferences and conformational flexibility. This is related to the CuII coordination chemistry and the reactivity of the dinuclear CuII complexes towards CO2 fixation. The variation observed between the natural and various synthetic peptide systems enables conclusions about structure–reactivity correlations, and our results also provide information on why nature might have chosen oxazolines and thiazoles as incorporated heterocycles. 相似文献
955.
《Analytical letters》2012,45(11):2252-2270
Abstract A novel adsorptive fast Fourier transform cyclic voltammetry (AFFTCV) technique for the fast determination of tramadol in flow‐injection systems has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping, and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 µm in radius). The proposed detection method has some advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, it is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the tramadol were considered. The method was linear over the concentration range of 1.5–900,000 pg/ml (r=0.9968) with a limit of detection and quantitation 0.32 and 1.5 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay tramadol in tablets and in biological fluids. 相似文献
956.
《Analytical letters》2012,45(16):3050-3059
Abstract Electrochemical investigation of the interaction of Ascorbic acid (AA) with bovine serum albumin (BSA) on a glassy carbon electrode is reported for the first time. In a 0.1 mol/l, pH 7.3 NaCl solution, AA had a well‐defined voltammetric oxidative peak at +0.2086 V (versus Ag/AgCl) on a GC electrode. After the addition of BSA into the AA solution, the oxidative peak current decreased significantly without a shift of the peak potential, and no new peak appeared. The experimental results showed that a new nonelectrochemical supramolecular complex was formed after the interaction of BSA with AA, which resulted in a decrease of the diffusion coefficient, and then a decrease of the oxidative peak current. The interaction conditions and the electrochemical detection conditions were carefully investigated. The stoichiometry of this supramolecular complex was calculated based on voltammetric data with a binding number of two and a binding constant of 1.38×107. 相似文献
957.
《Analytical letters》2012,45(4):582-592
Abstract A new type of gold nanoparticles–attached indium tin oxide electrode was made. By SEM and EDS, the as‐prepared gold nanoparticles–modified ITO electrode was characterized. This modified electrode has been used for the determination of pirarubicin (THP) in urine by cyclic voltammetry. Compared to a bare ITO electrode, the modified electrode exhibited a marked enhancement in the current response. Liner calibration curves are obtained in the range 5×10?9mol/L~1.5×10?6 mol/L with a detection limit of 1×10?9 mol/L. The percentage of the recoveries ranged from 99.3% to 106.3%. The practical analytic utility of the method is illustrated by quantitative determination of THP in urine. 相似文献
958.
《Analytical letters》2012,45(9):2105-2114
Abstract An analytical method of determination of methionine is proposed, based on electrochemical detection of the S-bound complex generated in the presence of the amminepentacyanoferrate (II) ion. 相似文献
959.
960.
《Analytical letters》2012,45(7):549-560
Abstract At -40°C, the behavior of lO compounds, differing widely in their standard potentials, has been investigated in liquid ammonia, using cyclic voltammetry at a smooth platinum electrode. The purpose of this study was the realization of a redox scale with reversible systems. With azobenzene, pyridazine, cin-noline, benzocinnoline and 4,4′-azobis-(pyridine-N-oxide), the first electron transfer is reversible and leads to the formation of the corresponding radical anions which are stable; the second electron transferleads to the ciianions which can be protonated yielding the corresponding hydrazo. Other compounds, such as azoxybenzene, 3-amino-1,2,4-triazine, pyridine-N-oxide, 8-azaadenine and 1H-tetrazole, have an electrochemical behavior which i s more intricate. 相似文献