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931.
The total synthesis of dysoxylactam A, a novel 17‐membered macrolactam with potent multi‐drug‐resistant reversing activities, has been achieved, starting from 4‐pentene‐1‐al in a longest linear sequence of 17 steps and 9.5% overall yield. The key transformations consist of iterative aldol and ring‐closing metathesis reactions for the construction of the stereochemically enriched polypropionate scaffold and the macrocycle, respectively. 相似文献
932.
Raghupathi Mutyala Venkatram R. Reddy Ravikiran Donthi V.S. Ramakrishna Kallaganti Rajesh Chandra 《Tetrahedron letters》2019,60(10):703-706
The enantioselective synthesis of the tetrahydropyranopyrazole scaffold has been achieved. The quinidine catalyzed reaction of allenoates with arylidenepyrazolones proceeded with high enantio- and diastereoselectivity while the reactions of alkylidenepyrazolones were less efficient. Allene ketones also afforded tetrahydropyranopyrazole derivatives in high yields, however, with only moderate enantioselectivity. The primary adduct undergoes further functional group transformations without effecting the initially formed chiral centre. 相似文献
933.
Nagamani Nuvula Gowrisankar M. Krishna T. Srinivasa Reddy K. Chandra Sekhara 《Journal of Thermal Analysis and Calorimetry》2019,138(4):2481-2489
Journal of Thermal Analysis and Calorimetry - Using recently constructed experimental phase diagram isotactic polypropylene–1,2,4,5-tetrachlorobenzene (TeCB), we formulate a physically... 相似文献
934.
Srikanth Annareddygari Venkateshwer Reddy Kasireddy Jayachandra Reddy 《Journal of heterocyclic chemistry》2019,56(12):3267-3276
A new and efficient method for the synthesis of various aza‐fused poly‐hetero aromatics has been described. This protocol includes an intermolecular condensation followed by metal‐free base‐promoted intramolecular C―N coupling reaction. The advantage of this one‐pot transformation lies in the use of simple cyclic amidines‐like compounds without prefunctionalization of the starting heterocycles. 相似文献
935.
Jhillu S. Yadav Nimmakayala Mallikarjuna Reddy N. Venkateswar Rao Md. Ataur Rahman Attaluri R. Prasad 《Helvetica chimica acta》2012,95(2):227-234
A convergent and efficient total synthesis of stagonolide C ( 1 ), a phytotoxic metabolite, was achieved (Schemes 2 and 3) The synthesis exploited the high configuration control in the Prins cyclization along with alkene rearrangement and ring‐closing metathesis as key steps. 相似文献
936.
Ryosuke Iinuma Poreddy Narsi Reddy Teruyuki Hayashi Masato Tanaka 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):441-450
Polymethylhydrosiloxane (PMHS) reacts with aliphatic and aromatic alcohols at room temperature in the presence of [CuH(PPh3)]6 complex catalyst to give poly[(methyl) (alkoxy)siloxane]s in high yields. Reactivity of alcohols decreases in the order of p‐methoxyphenol > p‐cresol > phenol > benzyl alcohol > allyl alcohol > ethanol > isopropanol > tert‐butyl alcohol. Partially p‐cresylated polymers, which still retain unreacted Si? H bonds, react further with ethylene glycol or water to form cross‐linked polymers, which, depending on the extent of cross linking, gelate during the cross‐linking process. Propargyl alcohol reacts with PMHS very rapidly to give exhaustively and partially propargyloxylated PMHS. Resulting polymers, upon heating, undergo crosslinking. Partially propargyloxylated polymers display high thermal stability [Td5 (temperature of 5% weight loss) > 500 °C] as compared with starting PMHS (243 °C) and exhaustively propargyloxylated one (414 °C). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
937.
An efficient method is described for the stereoselective synthesis of diorganyl chalcogenides from a variety of Baylis–Hillman acetates and diaryl chalcogens using palladium catalyst. This reaction is a convenient new method to produce unsymmetrical sulfides and selenides in good yields. 相似文献
938.
Arun Kumar Macharla Rohitha Chozhiyath Nappunni Mahender Reddy Marri Swamy Peraka Narender Nama 《Tetrahedron letters》2012,53(2):191-195
A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone® as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly. Aromatisation of tetralones is also carried out with this reagent system. 相似文献
939.
B.V. Subba Reddy P. Sivaramakrishna Reddy B. Phaneendra Reddy J.S. Yadav Ahamad Al Khazim Al Ghamdi 《Tetrahedron letters》2013
A stereoselective total synthesis of xyolide is described employing MacMillan α-hydroxylation, Steglich esterification, and ring closing metathesis as key steps. The use of organocatalytic MacMillan α-hydroxylation to construct two of the chiral centers of the xyolide makes this approach attractive. 相似文献
940.
Thummalapally Srikanth Reddy Dorigondla Kumar Reddy Manchala Narasimhulu Dasari Ramesh Yenamandra Venkateswarlu 《Helvetica chimica acta》2010,93(11):2158-2163
Total synthesis of mevinic acid analog 1 has been achieved efficiently starting from chiral 2,3‐O‐isopropylidene‐D ‐glyceraldehyde ( 2 ). The synthesis involves Mitsunobu reaction and Evans' intramolecular oxa‐Michael syn‐addition reactions as key steps. 相似文献