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61.
In the presence of the inexpensive and non‐toxic polymethylhydrosiloxane, the combination of copper(II) acetate and a chiral diphosphine displayed high catalytic efficiency in the asymmetric hydrosilylation of a series of aromatic ketones in air atmosphere and at room temperature. (R)‐1‐Arylethanols were obtained with up to 99% yield and 93% enantiomeric excess. Meanwhile, the electron effect and steric hindrance of substituents on the aromatic ring had an interesting influence on both the yields and enantioselectivities. Furthermore, a possible mechanism was presented to explain the influence of some key factors on the reaction. 相似文献
62.
Dr. Heng Liao Dr. Liu Zhong Dr. Zefan Xiao Dr. Ting Zheng Prof. Haiyang Gao Prof. Qing Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):14048-14055
A series of novel α‐diamine nickel complexes, (ArNH‐C(Me)‐(Me)C‐NHAr)NiBr2, 1 : Ar=2,6‐diisopropylphenyl, 2 : Ar=2,6‐dimethylphenyl, 3 : Ar=phenyl), have been synthesized and characterized. X‐ray crystallographic analysis showed that the coordination geometry of the α‐diamine nickel complexes is markedly different from conventional α‐diimine nickel complexes, and that the chelate ring (N‐C‐C‐N‐Ni) of the α‐diamine nickel complex is significantly distorted. The α‐diamine nickel catalysts also display different steric effects on ethylene polymerization in comparison to the α‐diimine nickel catalyst. Increasing the steric hindrance of the α‐diamine ligand by substitution of the o‐methyl groups with o‐isopropyl groups leads to decreased polymerization activity and molecular weight; however, catalyst thermal stability is significantly enhanced. Living polymerizations of ethylene can be successfully achieved using 1 /Et2AlCl at 35 °C or 2 /Et2AlCl at 0 °C. The bulky α‐diamine nickel catalyst 1 with isopropyl substituents can additionally be used to control the branching topology of the obtained polyethylene at the same level of branching density by tuning the reaction temperature and ethylene pressure. 相似文献
63.
A Convenient Synthesis of N‐Aryl Benzamides by Rhodium‐Catalyzed ortho‐Amidation and Decarboxylation of Benzoic Acids 下载免费PDF全文
Dr. Xian‐Ying Shi Ke‐Yan Liu Juan Fan Xue‐Fen Dong Prof. Dr. Jun‐Fa Wei Prof. Dr. Chao‐Jun Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1900-1903
The rhodium‐catalyzed amidation of substituted benzoic acids with isocyanates by directed C?H functionalization followed by decarboxylation to afford the corresponding N‐aryl benzamides is demonstrated, in which the carboxylate serves as a unique, removable directing group. Notably, less common meta‐substituted N‐aryl benzamides are generated readily from more accessible para‐ or ortho‐substituted groups by employing this strategy. 相似文献
64.
Asymmetric Michael Addition of Aldimino Esters with Chalcones Catalyzed by Silver/Xing‐Phos: Mechanism‐Oriented Divergent Synthesis of Chiral Pyrrolines 下载免费PDF全文
Xing‐Feng Bai Dr. Li Li Dr. Zheng Xu Dr. Zhan‐Jiang Zheng Prof. Dr. Chun‐Gu Xia Dr. Yu‐Ming Cui Prof. Dr. Li‐Wen Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10399-10404
The mechanism‐oriented reaction design for the divergent synthesis of chiral molecules from simple starting materials is highly desirable. In this work, aromatic amide‐derived nonbiarylatropisomer/silver (silver/Xing‐Phos) complex was used to catalyze the Michael addition of glycine aldimino esters to chalcones and successfully applied to the subsequent cyclocondensation to afford substituted cis‐Δ(1)‐pyrroline derivatives with up to 98 % ee. Besides the inherent performance of the chiral Ag/Xing‐Phos catalyst system, it was found that the workup of such reactions played an important role for the stereoselective construction of stereodivergent Δ(1)‐pyrrolines, in which an epimerization of the cis‐Δ(1)‐pyrrolines to the trans‐isomers during was revealed. 相似文献
65.
Inside Cover: Ru‐Catalysed CH Arylation of Indoles and Pyrroles with Boronic Acids: Scope and Mechanistic Studies (Chem. Eur. J. 14/2015) 下载免费PDF全文
66.
Detoxification of Chemical Warfare Agents Using a Zr6‐Based Metal–Organic Framework/Polymer Mixture 下载免费PDF全文
Dr. Su‐Young Moon Emmanuel Proussaloglou Gregory W. Peterson Dr. Jared B. DeCoste Morgan G. Hall Dr. Ashlee J. Howarth Prof. Joseph T. Hupp Prof. Omar K. Farha 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):14864-14868
Owing to their high surface area, periodic distribution of metal sites, and water stability, zirconium‐based metal–organic frameworks (Zr6‐MOFs) have shown promising activity for the hydrolysis of nerve agents GD and VX, as well as the simulant, dimethyl 4‐nitrophenylphosphate (DMNP), in buffered solutions. A hurdle to using MOFs for this application is the current need for a buffer solution. Here the destruction of the simulant DMNP, as well as the chemical warfare agents (GD and VX) through hydrolysis using a MOF catalyst mixed with a non‐volatile, water‐insoluble, heterogeneous buffer is reported. The hydrolysis of the simulant and nerve agents in the presence of the heterogeneous buffer was fast and effective. 相似文献
67.
A Gold(I)‐Catalyzed Domino Coupling of Alcohols with Allenes Enables the Synthesis of Highly Substituted Indenes 下载免费PDF全文
Alexander Preinfalk Dr. Antonio Misale Prof. Dr. Nuno Maulide 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14471-14474
The reaction of aryl‐substituted allenes with alcohols under gold catalysis led to highly substituted indenes in good yields, with low catalyst loading and under mild conditions. During this domino transformation, two C?C bonds are formed with water as the only byproduct. 相似文献
68.
Silver(I)‐Catalyzed Enantioselective [3+2]‐Cycloaddition Reaction of α‐Silylimines: A Facile Route to Quaternary‐Carbon‐Rich Scaffolds 下载免费PDF全文
Dr. Naredla Kesava‐Reddy Christopher Golz Prof. Dr. Carsten Strohmann Dr. Kamal Kumar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18373-18377
A silver‐catalyzed highly enantioselective 1,3‐dipolar cycloaddition reaction of α‐silylimines with pyrone‐based trisubstituted olefins was developed affording bi‐ and tricyclic α‐quaternary‐carbon‐rich pyrano‐pyrrolidines in excellent yields. The tricyclic benzopyrone adducts thus obtained were efficiently transformed into highly complex tetracyclic scaffolds supporting four consecutive stereogenic centers with three quaternary carbons. 相似文献
69.
Direct Estimation of the Surface Location of Immobilized Functional Groups for Concerted Catalysis Using a Probe Molecule 下载免费PDF全文
Hiroto Noda Dr. Ken Motokura Prof. Dr. Yusuke Wakabayashi Kaori Sasaki Dr. Hiroo Tajiri Dr. Akimitsu Miyaji Dr. Sho Yamaguchi Prof. Dr. Toshihide Baba 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5113-5117
The location of active sites during concerted catalysis by a metal complex and tertiary amine on a SiO2 surface is discussed based on the interaction between the functionalized SiO2 surface and a probe molecule, p‐formyl phenylboronic acid. The interactions of the probe molecule with the surface functionalities, diamine ligand, and tertiary amine, were analyzed by FT‐IR and solid‐state 13C and 11B MAS NMR. For the catalyst exhibiting high 1,4‐addition activity, the diamine ligand and tertiary amine base exist in closer proximity than in the catalyst with low activity. 相似文献
70.
Inside Back Cover: Deciphering a Nanocarbon‐Based Artificial Peroxidase: Chemical Identification of the Catalytically Active and Substrate‐Binding Sites on Graphene Quantum Dots (Angew. Chem. Int. Ed. 24/2015) 下载免费PDF全文