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31.
Heravi Majid M. Bakhtiari Khadijeh Alinejhad Hamideh Saeedi Mina Malakooti Reihane 《中国化学》2010,28(2):269-272
β‐Aminoalcohols were synthesized in high yields by reaction of epoxides with amines in the presence of MCM‐41 as a green and reusable catalyst under solvent‐free conditions. 相似文献
32.
Bamoharram Fatemeh F Roshani Mina Heravi Majid M Mahdavi Masoumeh Javid Ali Emampour Jalal Sh 《中国化学》2010,28(6):974-976
Isoxazolo[5,4‐d]pyrimidine‐4,6(5H,7H)diones 2a – 2f have been synthesized from the reaction of ethyl 5‐amino‐3‐methyl‐4‐isoxazole carboxylate ( 1 ) with aryl isocyanates in the presence of Keggin heteropolyacid H3[PW12O40] as a green solid acid catalyst at room temperature in a one‐pot process in good yields. 相似文献
33.
The electronic and steric effects of some Schiff bases and the solvent on the thermodynamic parameters of the pentacoordinate Co(III) Schiff base complexes were studied. The formation constants and the thermodynamic parameters were measured spectrophotometrically for 1:1 adduct formation of the complexes as acceptors with tributylphosphine (PBu3) as donor, in some solvents (acetonitrile, tetrahydrofuran, butanol, ethanol and N,N-dimethylformamide) in constant ionic strength (I = 0.01 M, sodium perchlorate) and at various temperatures. The trend of the reactivity of the pentacoordinate cobalt(III) Schiff base complexes toward tributylphosphine according to the solvent is as follows: acetonitrile > tetrahydrofuran > butanol > ethanol > N,N-dimethylformamide. The trend of the reactivity of pentacoordinate cobalt(III) Schiff base complexes toward the donor in a given solvent according to the equatorial Schiff base is as follows: BBE > BAE > Salen. 相似文献
34.
Issa Yavari Mina Haghdadi Rahebeh Amiri 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2015-2023
Ab initio calculations at HF/6-31+G? level of theory for geometry optimization, and MP2/6-31+G?//HF/6-31+G? and B3LYP/6-31+G?//HF/6-31+G? levels for a single-point total energy calculation, are reported for the chair and twist conformations of 1,2-dithiane (1), 3,3,6,6-tetramethyl-1,2-dithiane (2), 1,2,4,5-tetrathiane (3), and 3,3,6,6-tetramethyl-1,2,4,5-tetrathiane (4). The C2 symmetric chair conformations of 1 and 2 are calculated to be 21.9 and 8.6 kJ mol?1 more stable than the corresponding twist forms. The calculated energy barriers for chair-to-twist processes in 1 and 2 are 56.3 and 72.8 kJ mol?1, respectively. The C2h symmetric chair conformation of 3 is 10.7 kJ mol?1 more stable than the twist form. Interconversion of these forms takes place via a C2 symmetric transition state, which is 67.5 kJ mol?1 less stable than 3-Chair. The D2 symmetric twist-boat conformation of 4 is calculated to be 4.0 kJ mol?1 more stable than the C2h symmetric chair form. The calculated strain energy for twist to chair process is 61.1 kJ mol?1. 相似文献
35.
Batool Akhlaghinia Mozafar Asadi Elham Safaee Mozhgan Heydarpoor 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2099-2104
Alcohols and phenols are protected with hexamethyldisilazane in the presence of N,N′,N′,N?-tetramethyletra-2,3-pyridinoporphyrazinato copper (II) in good-to-excellent yields at room temperature. 相似文献
36.
Determination of Trichloroacetic Acid (TCAA) Using CdO Nanoparticles Modified Carbon Paste Electrode
In this paper, the electrochemical behavior of a carbon paste electrode modified with CdO nanoparticles as a potential electrocatalyst for the reduction of trichloroacetic acid (TCAA) was investigated using cyclic voltammetry and double‐potential step chronoamperometry. The modified electrode showed a great enhancement in cathodic peak current with respect to reduction of TCAA in acidic aqueous solution. Using this increment, a quantitative method was developed for the determination of TCAA in aqueous solution. The detection limit and linear dynamic range of TCAA are 2.3×10?6 M and 2.3×10?4–3×10?6 M, respectively. 相似文献
37.
应用从头算分子轨道法分别在RHF/6-31G**和UHF/6-31G**水平上对3腔┤┓肿拥幕?S0)和三重激发态(T1)单键旋转异构反应机理进行了研究,优化出反应物和产物在S0态和T1态的4种平衡态和过渡态的几何构型,通过振动分析得到的虚频和计算的内禀反应坐标对过渡态进行了确认,并得到了零点能,根据基态和激发态反应途径分析了光反应机理。计算结果表明,基态和激发态的3腔┤┓肿拥ゼ旃狗从ξ焕萁系停嘏湃菀追⑸永砺凵涎橹ち斯夥从κ笛橹屑钢忠旃固宓拇嬖凇? 相似文献
38.
Seyyed Mahmoud Mousavi Hamed Tavakoli Mohammad Samadfam Fatemeh Semnani Zahra Asadi Hamid Sepehrian 《Research on Chemical Intermediates》2013,39(3):951-959
Adsorption and recovery of uranium by nanoporous MCM-41 from aqueous solutions (synthetic solution and uranium conversion facility liquid waste) were investigated by use of a fixed-bed column (1.2 cm diameter and 3.0 cm height). Adsorption was carried out at flow rates 0.2 and 0.5 mL min?1, which correspond to retention times of 10 and 6 min. The maximum breakthrough capacity for uranium ions was achieved by use of nanoporous MCM-41 at the optimum pH of 3.6 and flow rate 0.2 mL min?1 (61.95 μg g?1). The Thomas and Yan models were applied to the experimental data, by use of linear regression, to determine the characteristics of the column for process design. The breakthrough curves calculated from the models were in good agreement with the experimental data. The elution behavior of uranium on nanoporous MCM-41 was studied with different eluents; the results showed that 0.1 M HCl is good eluent for uranium recovery. The regenerated column could be used in a multitude of adsorption–desorption cycles. 相似文献
39.
The main oral drug absorption barriers are fluid cell membranes, and generally drugs are absorbed by a passive diffusion mechanism. On the other hand, the blood–brain barrier (BBB) is considered to be the main barrier to drug transport into the central nervous system (CNS). The BBB restricts the passive diffusion of many drugs from blood to brain. Biopartitioning micellar chromatography (BMC), a mode of micellar liquid chromatography that uses micellar mobile phases in adequate experimental conditions, can be useful as an in vitro system in mimicking the drug partitioning process into biological systems. In this study, relationships between the BMC retention data of a heterogeneous set of 12 drugs and their pharmacokinetics parameters (human oral drug absorption and BBB penetration ability) are studied and the predictive ability of the models is evaluated. Modeling of log k BMC of these compounds was established by multiple linear regression in two different concentrations (0.07 and 0.09 M) of sodium dodecyl sulfate (SDS). The results showed a fair correlation between human oral drug absorption and BMC retention data in 0.09 M SDS (R 2 = 0.864) and a good correlation between the blood–brain distribution coefficient and BMC retention data in 0.07 M of SDS (R 2 = 0.887). Application of the developed models to a prediction set demonstrated that the model is also reliable with good predictive accuracy. The external and internal validation results showed that the predicted values are in good agreement with the experimental value. 相似文献
40.