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991.
Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of N?H Imines and Alkynes by C?H/N?H Activation
Ruoyu He Zhi‐Tang Huang Qi‐Yu Zheng Congyang Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(19):5050-5053
Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle. 相似文献
992.
Miao Wan Zhilin Meng Hongxiang Lou Lei Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(50):14065-14069
A trityl ion mediated C H functionalization of ethers with a wide range of nucleophiles at ambient temperature has been developed. The reaction displays high chemoselectivity and good functional group tolerance. The protocol also exhibits excellent regio‐ and diastereoselectivities for the unsymmetric ethers, thus stereoselectively generating highly functionalized disubstituted 2,5‐trans tetrahydrofurans (THF), 2,6‐trans tetrahydropyrans (THP), 2,6‐trans dihydropyrans (DHP), and 1,3‐trans isochromans, and highlighting the capacity of the protocol in complex molecule synthesis. 相似文献
993.
Jia‐Xuan Yan Hu Li Xiang‐Wei Liu Jiang‐Ling Shi Xin Wang Zhang‐Jie Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(19):5045-5049
3,4‐Dihydroquinolinones were synthesized by the palladium‐catalyzed, oxidative‐addition‐initiated activation and arylation of inert C(sp3) H bonds. Pd(OAc)2 and P(o‐tol)3 were used as the catalyst and ligand, respectively, to improve the efficiency of the reaction. A further advantage of this reaction is that it could be performed in air. A relatively rare seven‐membered palladacycle was proposed as a key intermediate of the catalytic cycle. 相似文献
994.
Nusrah Hussain Gustavo Frensch Jiadi Zhang Patrick J. Walsh 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(14):3767-3771
The combination of aryl bromides, allylbenzene, base and a palladium catalyst usually results in a Heck reaction. Herein we combine these same reagents, but override the Heck pathway by employing a strong base. In the presence of LiN(SiMe3)2, allylbenzene derivatives undergo reversible deprotonation. Transmetalation of the resulting allyllithium intermediate to LPdAr(Br) and reductive elimination provide the 1,1‐diarylprop‐2‐enes, which are not accessible by the Heck reaction. The regioselectivity in this deprotonative cross‐coupling process is catalyst‐controlled and very high. 相似文献
995.
996.
Ying Dong Bangyu Liu Peng Chen Qun Liu Mang Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(13):3510-3514
The insertion of an aryne into a C S bond can suppress the addition of an S nucleophile to the aryne in the presence of palladium. Catalyzed by Pd(OAc)2, a wide range of α‐carbamoyl ketene dithioacetals readily react with arynes to selectively afford functionalized 2‐quinolinones in high yields under neutral reaction conditions by a C S activation/aryne insertion/intramolecular coupling sequence. The attractive feature of the new strategy also lies in the versatile transformations of the alkythio‐substituted quinolinone products. 相似文献
997.
Chao Wang Changpeng Chen Jingyu Zhang Jian Han Qian Wang Kun Guo Pei Liu Mingyu Guan Yingming Yao Yingsheng Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10042-10046
An easily synthesized and accessible N,O‐bidentate auxiliary has been developed for selective C H activation under palladium catalysis. The novel auxiliary showed its first powerful application in C H functionalization of remote positions. Both C(sp2) H and C(sp3) H bonds at δ‐ and ε‐positions were effectively activated, thus giving tetrahydroquinolines, benzomorpholines, pyrrolidines, and indolines in moderate to excellent yields by palladium‐catalyzed intramolecular C H amination. 相似文献
998.
Qian Li Matthias Driess John F. Hartwig 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(32):8611-8614
Reported herein is an iridium‐catalyzed, regioselective silylation of the aromatic C H bonds of benzylamines and the benzylic C H bonds of 2,N‐dialkylanilines. In this process, (hydrido)silyl amines, generated in situ by dehydrogenative coupling of benzylamine or aniline with diethylsilane, undergo selective silylation at the C H bond γ to the amino group. The products of this silylation are suitable for subsequent oxidation, halogenation, and cross‐coupling reactions to deliver benzylamine and arylamine derivatives. 相似文献
999.
1000.
Iodine-catalyzed three component reaction of quinazoline-2,5-diones, aldehydes, and styrenes provides allylamine derivatives was described. Both paraformaldehyde and ethyl glyoxalate can be applied in this reaction with simple styrenes with high regioselectivity. 相似文献