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111.
Interaction of 1,1,2,3,3-pentafluoro-1,5-hexadiene with Br2 in a MeCOOH medium results in the product of selective bromination of the hydrocarbon double bond,i.e., 5,6-dibromo-1,1,2,3,3-pentafluoro-1-hexene. Epoxidation of the latter with H2O2 in an alkaline medium followed by debromination afforded 5,6-epoxy-4,4,5,6,6-pentafluoro-1-hexene for the first time.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1530–1533, August, 1995. 相似文献
112.
Complexed cyclopropyl-3,4-dihydroxyphenylalanine (∇ DOPA) were synthesized by diazomethane cyclopropanation of the appropriate diene(tricarbonyl)iron complexes linked to azlactones. Opening of the oxazolone ring by treatment with MeOH and DMAP gave the corresponding methyl esters. Introduction of the Boc group, cleavage of the carbamate with hydrazine provided Boc-protected cyclopropylogs of dl-dihydroxyphenylalanine. 相似文献
113.
Optically active cyclic compounds carrying a conjugate diene and two hydroxy groups were prepared through the intramolecular Büchner reaction with a chiral tether and succeeding stereoselective conversion. Hydrogenation of the diene in the first step was not regioselective but resulted in three regioisomeric monoenes. Nevertheless, the final saturated product carrying two stereogenic centers could be obtained in 98% stereochemical purity on further hydrogenation under optimized conditions. The high stereoselectivity throughout the multiple pathways is attributable to the effective direction by the hydroxy group. Ring cleavage of the produced stereochemically pure seven-membered ring compounds successfully resulted in synthetic intermediates for deoxypolypropionates. 相似文献
114.
The (2E,4E)‐ and (2E,4Z)‐1‐phenyl‐1,6‐dioxo‐hepta‐2,4‐diene reacts with aziridine to give aziridinecyclopentenol 3. This product arises from an intermolecular Michael addition of a nitrogen lone pair to the less reactive enone, followed by an intramolecular aldol reaction of the enol with ketone. Furthermore, the initially formed enol did not undergo nucleophilic attack onto the aziridine ring to form heterocycles. Interestingly, the reaction with secondary amine did not give the cyclopentenol adduct, and this only leads to the isomerization of (2E,4Z)‐1‐phenyl‐1,6‐dioxo‐hepta‐2,4‐diene to the more stable (2E,4E)‐1‐phenyl‐1,6‐dioxo‐hepta‐2,4‐diene by addition to the more reactive enone. 相似文献
115.
Yuhang Zhu Yilei Liao Shuqi Jin Liyuan Ding Prof. Dr. Guofu Zhong Prof. Dr. Jian Zhang 《Chemical record (New York, N.Y.)》2023,23(5):e202300012
Aryl alkenes represents one of the most widely occurring structural motif in countless drugs and natural products, and direct C−H functionalization of aryl alkenes provides atom- step efficient access toward valuable analogues. Among them, group-directed selective olefinic α- and β-C−H functionalization, bearing a directing group on the aromatic ring, has attracted remarkable attentions, including alkynylation, alkenylation, amino-carbonylation, cyanation, domino cyclization and so on. These transformations proceed by endo- and exo−C−H cyclometallation and provide aryl alkene derivatives in excellent site- stereo-selectivity. Enantio-selective α- and β- olefinic C−H functionalization were also covered to synthesis axially chiral styrenes. 相似文献
116.
Mannepalli Lakshmi Kantam Vura Bala Subrahmanyam Kota Balaji Shiva Kumar Gopaladasu T. Venkanna Bojja Sreedhar 《Helvetica chimica acta》2008,91(10):1947-1953
Rhodium fluoroapatite (RhFAP) is an efficient catalyst for conjugate addition of organoboron reagents to α,β‐unsaturated carbonyl compounds. A variety of arylboronic acids and α,β‐unsaturated carbonyl compounds were converted to the corresponding conjugate‐addition products, demonstrating the versatility of the reaction. The reaction is highly selective. RhFAP was recovered quantitatively by simple filtration, and reused for four cycles. 相似文献
117.
118.
《中国化学》2018,36(10):929-933
A new palladium‐catalyzed selective aminomethylation of conjugated 1,3‐dienes with aminals via double C—N bond activation is described. This simple method provides an effective and rapid approach for the synthesis of linear α,β‐unsaturated allylic amines with perfect regioselectivity. Mechanistic studies disclosed that one palladium catalyst cleaved two distinct C—N bond to furnish a cascade double C—N bond activation, in which an allylic 1,3‐diamine and allylic 1,2‐diamine were initially formed as key intermediates through the palladium‐catalyzed C—N bond activation of aminal and the α,β‐unsaturated allylic amine was subsequently produced via palladium‐catalyzed C—N bond activation of the allylic diamines. 相似文献
119.
120.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(15):1705-1710
Five types of ethylene/α‐alkene model copolymers containing 21‐carbon alkyl branches have been synthesized via acyclic diene metathesis (ADMET) copolymerization. The overall branch content is controlled by varying the feedstock ratio of the long‐chain branched symmetrical α, ω‐diene and 1,9‐decadiene. Well‐defined melting transitions are present at low branch incorporation, followed by the broadening of the endotherms as the branch contents increase. However, instead of making the material amorphous, further increasing of the branch contents leads to the retrieval of the semi‐crystalline material creating a new crystalline domain, branches that co‐crystallize. Detailed IR spectra analyses suggest a crystal morphology transformation from orthorhombic to hexagonal phase as the branch content increases in these polymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 相似文献