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81.
Transition from π Radicals to σ Radicals: Substituent‐Tuned Cyclization of Hydrazonyl Radicals
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Xiu‐Long Yang Prof. Dr. Wei Yu Prof. Dr. Bing Han 《Angewandte Chemie (International ed. in English)》2014,53(12):3158-3162
Hydrazonyl radicals are known for their π‐electronic structures; however, their σ‐electronic structures have not been reported as yet. Herein, we show that readily accessible β,γ‐ and γ,δ‐unsaturated N‐trichloroacetyl and N‐trifluoroacetyl hydrazones can be conveniently converted into hydrazonyl σ radicals, which subsequently undergo 5‐exo‐trig radical cyclization at the N1 or N2 atom to form pyrazolines and azomethine imines, respectively. 相似文献
82.
Copper‐Catalyzed Intermolecular Trifluoromethylazidation of Alkenes: Convenient Access to CF3‐Containing Alkyl Azides
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Fei Wang Xiaoxu Qi Zhaoli Liang Dr. Pinhong Chen Prof. Dr. Guosheng Liu 《Angewandte Chemie (International ed. in English)》2014,53(7):1881-1886
A novel copper‐catalyzed intermolecular trifluoromethylazidation of alkenes has been developed under mild reaction conditions. A variety of CF3‐containing organoazides were directly synthesized from a wide range of olefins, including activated and unactivated alkenes, and the resulting products can be easily transformed into the corresponding CF3‐containing amine derivatives. 相似文献
83.
Copper‐Catalyzed Cross‐Coupling of Boronic Esters with Aryl Iodides and Application to the Carboboration of Alkynes and Allenes
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Yiqing Zhou Wei You Kevin B. Smith Prof. M. Kevin Brown 《Angewandte Chemie (International ed. in English)》2014,53(13):3475-3479
Copper‐catalyzed Suzuki–Miyaura‐type cross‐coupling and carboboration processes are reported. The cross‐couplings function well with a variety of substituted aryl iodides and aryl boronic esters and allows for orthogonal reactivity compared to palladium‐catalyzed processes. The carboboration method includes both alkynes and allenes and provides access to highly substituted and stereodefined vinyl boronic esters. The alkyne carboboration method is highlighted in the simple one‐pot synthesis of Tamoxifen. 相似文献
84.
Recent Progress in Direct Introduction of Fluorinated Groups on Alkenes and Alkynes by means of CH Bond Functionalization
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Dr. Tatiana Besset Dr. Thomas Poisson Prof. Xavier Pannecoucke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):16830-16845
The direct introduction of fluorine and fluorinated building blocks has recently attracted a lot of attention and particularly the direct functionalization of alkenes and alkynes. This review will highlight the major progress recently made in that field, with a focus on photocatalyzed transformations, base‐promoted processes, and transition metal‐catalyzed functionalization of alkenes and alkynes. Special attention will be paid to explanations of the reaction mechanisms. 相似文献
85.
Yong‐Gang Zhang Xiang‐Lei Liu Zeng‐Yang He Xi‐Ming Li Hong‐Jian Kang Prof. Dr. Shi‐Kai Tian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(10):2765-2769
An unprecedented oxidative arylation reaction of terminal alkenes with simple aroyl hydrazides has been developed under aerobic conditions for the stereoselective synthesis of 1,2‐disubstituted alkenes. A range of aroyl hydrazides underwent palladium/copper‐catalyzed oxidative Mizoroki–Heck reaction with terminal alkenes open to air in a 1:1 mixture of dimethyl sulfoxide and acetonitrile to give structurally diverse 1,2‐disubstituted alkenes in moderate to excellent yields with excellent regio‐ and E‐selectivity. The reaction tolerated a wide variety of functional groups, such as alkoxy, hydroxy, amino, fluoro, chloro, bromo, cyano, nitro, ester, amide, imide, phosphine oxide, and sulfone groups, and, moreover, molecular oxygen and dimethyl sulfoxide were demonstrated to serve as terminal oxidants. This study provides a useful method for the stereoselective synthesis of 1,2‐disubstituted alkenes through direct transformation of the vinylic C?H bonds in terminal alkenes. 相似文献
86.
Phosphine‐Catalyzed [3+2] Cycloaddition Reactions of Azomethine Imines with Electron‐Deficient Alkenes: A Facile Access to Dinitrogen‐Fused Heterocycles
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Zhen Li Hao Yu Honglei Liu Lei Zhang Hui Jiang Bo Wang Prof. Dr. Hongchao Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1731-1736
An efficient method for the phosphine‐catalyzed [3+2] cycloaddition reaction of azomethine imines with diphenylsulfonyl alkenes to give dinitrogen‐fused bi‐ or tricyclic heterocyclic compounds in high yields has been described. Moreover, two phenylsulfonyl groups installed on the heterocyclic products could be conveniently removed or transformed to other functional groups, making the reaction more useful. 相似文献
87.
Efficient Copper‐Catalyzed Direct Intramolecular Aminotrifluoromethylation of Unactivated Alkenes with Diverse Nitrogen‐Based Nucleophiles
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Dr. Jin‐Shun Lin Ya‐Ping Xiong Can‐Liang Ma Li‐Jiao Zhao Prof. Dr. Bin Tan Prof. Dr. Xin‐Yuan Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(5):1332-1340
A mild, convenient, and step‐economical intramolecular aminotrifluoromethylation of unactivated alkenes with a variety of electronically distinct, nitrogen‐based nucleophiles in the presence of a simple copper salt catalyst, in the absence of extra ligands, is described. Many different nitrogen‐based nucleophiles (e.g., basic primary aliphatic and aromatic amines, sulfonamides, carbamates, and ureas) can be employed in this new aminotrifluoromethylation reaction. The aminotrifluoromethylation process allows straightforward access to diversely substituted CF3‐containing pyrrolidines or indolines, in good to excellent yields, through a direct difunctionalization strategy from the respective acyclic starting materials. Mechanistic studies were conducted and a plausible mechanism was proposed. 相似文献
88.
Dr. Jeffrey Y. W. Mak Dr. Rebecca H. Pouwer Assoc. Prof. Craig M. Williams 《Angewandte Chemie (International ed. in English)》2014,53(50):13664-13688
Well over a hundred years ago, Professor Julius Bredt embarked on a career pursuing and critiquing bridged bicyclic systems that contained ring strain induced by the presence of a bridgehead olefin. These endeavors founded what we now know as Bredt’s rule (Bredtsche Regel). Physical, theoretical, and synthetic organic chemists have intensely studied this premise, pushing the boundaries of such systems to arrive at a better understood physical phenomenon. Mother nature has also seen fit to construct molecules containing bridgehead double bonds that encompass Bredt’s rule. For the first time, this topic is reviewed in a natural product context. 相似文献
89.
Caitlin M. McMahon Prof. Erik J. Alexanian 《Angewandte Chemie (International ed. in English)》2014,53(23):5974-5977
A palladium‐catalyzed, intermolecular Heck‐type coupling of alkyl iodides and alkenes is described. This process is successful with a variety of primary and secondary unactivated alkyl iodides as reaction partners, including those with hydrogen atoms in the β position. The mild catalytic conditions enable intermolecular C? C bond formations with a diverse set of alkyl iodides and alkenes, including substrates containing base‐ or nucleophile‐sensitive functionality. 相似文献
90.
Dr. Wangqing Kong Dr. Estíbaliz Merino Prof. Dr. Cristina Nevado 《Angewandte Chemie (International ed. in English)》2014,53(20):5078-5082
Two radical‐mediated processes of activated alkenes, namely arylphosphonylation and arylazidation, are described. The difunctionalization of alkenes by a tandem process that involves radical addition, 1,4‐aryl migration, and desulfonylation generates α‐aryl‐β‐heterofunctionalized amides bearing a quaternary stereocenter when the substituent on the nitrogen atom is an aryl group. Alternatively, heterooxindoles or spirobicycles can be obtained with excellent regioselectivity in the presence of an alkyl substituent on the nitrogen atom. 相似文献