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Introduction Diastereoselective construction of 1,3-diheteroatom units, especially 1,3-amino alcohols and 1,3-diols, has always been in high demands in synthetic organic chemistry, as they are widely present in many natural products and potent drugs, such as nucleoside antibiot-ics and the HIV protease inhibitors.1,2 They have also been used as chiral ligands for asymmetric catalysts and as synthetic intermediates.3 Although several methods for the construction of 1,3-amino alcohols have been… 相似文献
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Sandra Hübner Dirk Michalik Dr. Haijun Jiao Dr. Helfried Neumann Dr. Stefan Klaus Dirk Strübing Dr. Anke Spannenberg Dr. Matthias Beller Prof. Dr. 《化学:亚洲杂志》2007,2(6):734-746
Chiral N‐dienyl lactams are crucial building blocks for the synthesis of complex organic compounds. However, their generation is rather challenging. This paper reports the novel one‐pot reaction of (S)‐methyl pyroglutamate as the a mide component with different a ldehydes and d ienophiles (AAD reaction) to give novel chiral 1‐amido‐2‐cyclohexenes. The corresponding N‐dienyl lactams generated in situ undergo subsequent Diels–Alder reactions in good yield and diastereoselectivity. The scope and limitations of the three‐component protocol were investigated. X‐ray and NMR spectroscopic analysis of the products as well as DFT calculations of the intermediates were also performed to explain the observed stereoselectivity and structural features. 相似文献
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A. S. Saghiyan A. V. Geolchanyan L. L. Manasyan G. M. Mkrtchyan N. R. Martirosyan S. A. Dadayan T. V. Kochickyan V. S. Harutyunyan A. A. Avetisyan V. I. Tararov V. I. Maleev Yu. N. Belokon' 《Russian Chemical Bulletin》2004,53(4):932-935
An efficient method was developed for the asymmetric synthesis of (R)-S-(1,2,4-triazol-3-yl)cysteines by the addition of 3,4-disubstituted 1,2,4-triazole-5-thiols at the electrophilic C=C bond in a NiII complex of a Schiff base of dehydroalanine with (S)-N-(N-benzylprolyl)aminobenzophenone. The stereoselectivity of the formation of diastereomeric complexes with the (S,R) configuration under conditions of thermodynamic control of the nucleophilic addition exceeds 94%. Acid treatment of the reaction mixtures afforded enantiomerically pure (R)-S-hetarylcysteines (ee >98%). 相似文献
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负载锰卟啉催化乙酰胆固醇的选择性环氧化 总被引:1,自引:0,他引:1
多相金属卟啉催化剂已经被用于普通烯烃的环氧化,如表面修饰的多孔分子筛(MCM 41)[1 3],本文制备了高分子负载型锰卟啉用作胆固醇的非对映选择性环氧化催化剂。转化率可达100%,β选择性可达99%。1 实验部分乙酰胆固醇按文献[4]合成。溶剂均为AR级,按文献方法纯化。将Merrifield sPeptideresin(Aldrich,2%,交联度,200-400目,≈2mmolCl/g)加入到精制的DMF中,室温下放置24h,加入5-(对羟基苯基)-10,15,20-三(对甲基苯基)卟啉及无水K2CO3,N2保护下,80℃反应6h,洗涤干燥得到催化剂[1](图1)。催化环氧化反应 将PhIO及催化剂按化学计… 相似文献
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Filippi A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(21):5396-5403
The model reaction between the (R)-1,3-dimethyl-1-cyclohexyl cation (I) and methanol has been investigated under gas-phase radiolytic conditions (750 Torr; 25-120 degrees C) with the aim of evaluating the intrinsic factors that govern the facial selectivity of biased carbocations. The peculiarity of the experimental approach allows the formation of different CH(3) (18)OH.I ionic adducts. Subsequent conversion of these adducts to give the corresponding E/Z covalent products follows different reaction coordinates, which are characterized by their own activation parameters. On the grounds of density functional theory (DFT) results, several [CH(3)OH.I] structures have been located on the relevant potential-energy surface (PES). The experimental results point to a gas-phase facial selectivity, which is mainly governed by entropic factors that arise as a result of the occurrence of different noncovalent ion-molecule "facial adducts" (FA). The formation of FAs may also play an important role in both the reaction dynamics and the positional selectivity. The present results cannot be interpreted by any of the models based on solution-phase experiments. 相似文献
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The attempted Baylis-Hillman reactions of sulfonyl aldimines or aryl aldehydes with 3-methylpenta-3,4-dien-2-one or 3-benzylpenta-3,4-dien-2-one gave the corresponding Baylis-Hillman adducts in moderate yields in DMSO under the catalysis of DBU or PMe3, respectively. Moderate diastereoselectivities were observed in the reaction of 3-benzylpenta-3,4-dien-2-one with N-arylmethylidene-1-naphthalenesulfonamides catalyzed by chiral catalyst cinchona alkaloid derivative TQO {4-(3-ethyl-4-oxa-1-azatricyclo[4.4.0.0^3,8]dec-5-yl)quinolin-6-ol}. 相似文献
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