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991.
Mingjie Wen Xiru Cao Yongqi Zhang Meng Liang Tianlei Zhang Balaganesh Muthiah Ke Zhou Soumendra K. Roy Makroni Lily 《International journal of quantum chemistry》2020,120(23):e26389
A detailed theoretical study on the reaction mechanisms for the formations of H2O2 + 3O2 from the self-reaction of HO2 radicals under the effect of NH3, H3N···H2O, and H2SO4 catalysts was performed using the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ method. The rate constant was computed using canonical variational transition state theory (CVT) with small curvature tunneling (SCT). Our results indicate that NH3-, H3N···H2O-, and H2SO4-catalyzed reactions could proceed through both one-step and stepwise routes. Calculated rate constants show that the catalyzed routes in the presence of the three catalysts all prefer stepwise pathways. Compared to the catalytic efficiency of H2O, the efficiencies of NH3, H3N···H2O, and H2SO4 are much lower due to their smaller relative concentrations. The present results have provided a definitive example of how basic and acidic catalysts influence the atmospheric reaction of HO2 + HO2 → H2O2 + 3O2. These results further encourage one to consider the effects of basic and acidic catalysts on the related atmospheric reactions. Thus, the present investigation should have broad implications in the gas-phase reactions of the atmosphere. 相似文献
992.
Yaosong Huang Yugong Chen Mingfei Zhou 《International journal of quantum chemistry》2020,120(24):e26415
Hexamethyldisiloxane [HMDSO, (CH3)3-SiOSi-(CH3)3] is an important precursor for SiO2 formation during flame-based silica material synthesis. As a result, HMDSO reactions in flame have been widely investigated experimentally, and many results have indicated that HMDSO decomposition reactions occur very early in this process. In this paper, quantum chemical calculations are performed to identify the initial decomposition of HMDSO and its subsequent reactions using the density functional theory at the level of B3LYP/6-311+G (d, p). Four reaction pathways—(a) Si O bond dissociation of HMDSO, (b) Si C bond dissociation of HMDSO, (c) dissociation and recombination of Si O and Si C bonds, and (d) elimination of a methane molecule from HMDSO—have been examined and identified. From the results, it is found that the barrier of 84.38 kcal/mol and Si O bond dissociation energy of 21.55 kcal/mol are required for the initial decomposition reaction of HMDSO in the first pathway, but the highest free energy barrier (100.69 kcal/mol) is found in the third reaction pathway. By comparing the free energy barriers and reaction rate constants, it is concluded that the most possible initial decomposition reaction of HMDSO is to eliminate the CH3 radical by Si C bond dissociation. 相似文献
993.
Dr. Jian‐Bo Xie Prof. Jian‐Hua Xie Xiao‐Yan Liu Qian‐Qian Zhang Prof. Qi‐Lin Zhou 《化学:亚洲杂志》2011,6(3):899-908
The iridium complexes of chiral spiro aminophophine ligands, especially the ligand with 3,5‐di‐tert‐butylphenyl groups on the P atom ( 1c ) were demonstrated to be highly efficient catalysts for the asymmetric hydrogenation of alkyl aryl ketones. In the presence of KOtBu as a base and under mild reaction conditions, a series of chiral alcohols were synthesized in up to 97 % ee with high turnover number (TON up to 10 000) and high turnover frequency (TOF up to 3.7×104 h−1). Investigation on the structures of the iridium complexes of ligands (R)‐ 1a and 1c by X‐ray analyses disclosed that the 3,5‐di‐tert‐butyl groups on the P‐phenyl rings of the ligand are the key factor for achieving high activity and enantioselectivity of the catalyst. Study of the catalysts generated from the Ir‐(R)‐ 1c complex and H2 by means of ESI‐MS and NMR spectroscopy indicated that the early formed iridium dihydride complex with one (R)‐ 1c ligand was the active species, which was slowly transformed into an inactive iridium dihydride complex with two (R)‐ 1c ligands. A plausible mechanism for the reaction was also suggested to explain the observations of the hydrogenation reactions. 相似文献
994.
Phosgene has attracted wide attention because of its important applications and value in modern industry, agriculture, and other fields, though it easily leaks and is difficult to detect. In this work, we designed and synthesized a naphthalimide-based fluorescent probe, which is easy to prepare, stable, and able to discriminate between phosgene, acetyl chloride, oxalyl chloride, thionyl chloride, phosphorus oxychloride, and tosyl chloride. Our results indicate that the probe can react with phosgene selectively and sensitively, showing remarkable ratiometric fluorescence changes. Furthermore, the probe can be made into test strips, which can determine phosgene in air effectively. The present work provides a novel class of naphthalimide-based derivatives with potential application in phosgene sensing in real time simply and safely with further optimization. 相似文献
995.
996.
This work described an interesting phenomenon of the stereoselective adsorption behaviors of DNA on stable chiral surfaces which were modified with 1,2‐diphenylethylenediamine enantiomers on gold electrodes. The modification process and electrochemical characterization of the chiral surfaces were measured by cyclic voltammetry (CV). The stereoselective adsorption behaviors of DNA on the two chiral surfaces were investigated via atomic force microscopy (AFM), CV, electrochemical impedance spectroscopy (EIS) and quartz crystal microbalance (QCM). All results confirmed that (1R,2R)‐1,2‐diphenylethylenediamine modified surface had stronger interaction with DNA molecules than (1S,2S)‐1,2‐diphenylethylenediamine modified surface, and the chirality of the surfaces created an different effect on the morphology and adsorption quantity of DNA. 相似文献
997.
Jiamei Liu Fang Wang Zhen Li Jianwei Zhou Jing Chen Chungu Xia 《Structural chemistry》2011,22(5):1119-1130
A new zwitterion containing 1,1,3,3-tetramethylguanidine was synthesized using a simple method, and the physicochemical properties
as well as the crystal structure of the compound were also studied. Two new acidic ionic liquids (ILs) were synthesized using
the zwitterion as the precursor and the physicochemical properties including density, viscosity, thermal property, and acidic
scale of the ILs were investigated. A density functional theory investigation of the geometrical structures and electronic
properties of the guanidinium triflate ionic liquid was also presented for better understanding the new ILs. 相似文献
998.
Zhi‐Cheng Qiu Jing‐Jing Zhang Yan Zhou Bo‐Ya Song Jing‐Jing Chang Ke‐Ke Yang Yu‐Zhong Wang 《先进技术聚合物》2011,22(6):993-1000
Poly(p‐dioxanone) (PPDO)/vermiculite (VMT) nanocomposites with exfoliated structure were prepared successfully by in situ intercalative polymerization of p‐dioxanone (PDO) in the presence of organo‐modified vermiculite (OVMT) with the aid of ultrasonic action. The nano‐structure of the nanocomposites was established using X‐ray diffraction (XRD) analysis and transmission electron microscopy (TEM) observations. The investigation of crystallization behavior by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) proved that exfoliated OVMT platelets acted as a template for spherulite growth. The thermal stability of nanocomposites was enhanced than that of pure PPDO. Dynamic mechanical analysis (DMA) indicated nanoscale OVMT platelets restricted the motion of PPDO segments, which benefitted the increase of storage and loss modulus. The tensile properties showed that nanocomposites were reinforced and toughened significantly by the addition of nanoscale OVMT platelets. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
999.
1000.
The curing process of a polysulfide (PSF) with a triacrylate crosslinker in the presence of an amine catalyst at room temperature is a rapid Michael addition. This reaction was monitored by real‐time infrared spectrum (RTIR). The results of the RTIR show that the consumptions of thiol and acrylate are stoichiometric until 80% conversion, indicating the characteristics of a “click” reaction. Dielectric analyzer (DEA) and dynamic mechanical analyzer (DMA) were employed to investigate the curing kinetics from which the activation energies of this curing reaction were obtained and shown to correlate with each other. In addition, the influences of the types and amount of amine catalyst, the different molecular weights of PSFs, and the triacrylate crosslinkers were discussed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献