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1.
2.
The synthesis of densely functionalized pyrrolo[2,1-a]isoquinolines was accomplished using the organocatalytic [3+2] cycloaddition between enals and azomethine ylides under iminium catalysis developed in our group some years ago as the key step. The cycloaddition proceeds smoothly yielding the corresponding pyrrolidine as a single endo diastereoisomer with enantiopurity in the range of 94–96% and further manipulations of the obtained cycloadducts using high yielding reaction protocols and a final mesylation/intramolecular N-alkylation sequence allowed the synthesis of target compounds in which the integrity of all stereocenters installed during the first step is maintained. 相似文献
3.
Andrés Reyes José Luis Sanz‐Vicario 《International journal of quantum chemistry》2010,110(13):2331-2331
4.
Antonio J. Meléndez‐Martínez Maria L. Escudero‐Gilete Isabel M. Vicario Francisco J. Heredia 《Journal of separation science》2009,32(11):1838-1848
The efficiency of C30 stationary phases in the separation of carotenes and diverse hydroxycarotenoids has been the subject of several studies. However, little is known concerning their ability to resolve epoxycarotenoids isomers, whose study is of great importance due to the functions they serve and the information they can reveal concerning the processing of foods. We have concluded that C30 columns provide an excellent separation of structural, geometrical and optical isomers of epoxycarotenoids and that the presence of 5,8‐epoxide groups leads to a better shape recognition, to the extent that over 10 geometrical–optical isomers of 5,8‐epoxycarotenoids have been separated. Additionally, it was observed that these carotenoids elute later than their 5,6‐epoxide counterparts, albeit the latter have a longer chromophore. 相似文献
5.
Silvia Reboredo Prof. Efraím Reyes Prof. Jose L. Vicario Prof. Dr. Dolores Badía Prof. Luisa Carrillo Dr. Abel de Cózar Prof. Dr. Fernando P. Cossío 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(23):7179-7188
The catalytic enantioselective [3+2] cycloaddition between azomethine ylides and α,β‐unsaturated aldehydes catalyzed by α,α‐diphenylprolinol has been studied in detail. In particular, the reaction has been extended to the use of 2‐alkenylidene aminomalonates generated in situ as azomethine ylide precursors. These reactions lead to the formation of pyrrolidines containing a 5‐alkenyl side chain with potential for chemical manipulation. Moreover, a detailed and concise computational study has been carried out to understand the exact nature of the mechanism of this reaction and especially the consequences derived from the incorporation of the chiral secondary amine catalyst on the reaction pathway. 相似文献
6.
Ruiz N Reyes E Vicario JL Badía D Carrillo L Uria U 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(30):9357-9367
The organocatalytic conjugate addition of different aldehydes to beta-nitroacrolein dimethyl acetal, generating the corresponding highly functionalized nitroaldehydes in high yields and with high stereoselectivities, has been studied in detail. These transformations have been achieved by using both readily available starting materials in a 1:1 ratio as well as commercially available catalysts at a 10 mol % catalyst loading. Furthermore, a very short and efficient protocol has been devised for the preparation of highly enantioenriched pyrrolidines containing two or three contiguous stereocenters starting from the obtained Michael adducts. 3,4-Disubstituted pyrrolidines have been obtained in a single step by Zn-mediated chemoselective reduction of the nitro group followed by intramolecular reductive amination, and trisubstituted homoproline derivatives have been prepared by means of an olefination reaction and a cascade process involving chemoselective reduction of the nitro group followed by a fully diastereoselective intramolecular aza- Michael reaction. 相似文献
7.
Fernández N Carrillo L Vicario JL Badía D Reyes E 《Chemical communications (Cambridge, England)》2011,47(45):12313-12315
We have developed a highly efficient procedure for carrying out the catalytic enantioselective (3+2) cycloaddition between enals and stable azomethine ylides such as isoquinolinium and phthalizinium methylides. Under the optimized reaction conditions highly substituted chiral pyrroloisoquinolines and pyrrolophthalazines have been obtained in high yields and excellent diastereo- and enantioselectivities. 相似文献
8.
Katsonis N Vicario J Kudernac T Visser J Pollard MM Feringa BL 《Journal of the American Chemical Society》2006,128(48):15537-15541
The structure of molecular monolayers formed at the interface between atomically flat surfaces and a solution of free-base meso-tetradodecylporphyrins (H2Ps) was examined by scanning tunneling microscopy (STM) at the liquid/solid interface. On the surface of graphite (HOPG), H2Ps form a well-ordered monolayer characterized by an oblique unit cell. On Au(111), H2Ps form a self-organized monolayer comprised of two distinct domain types. In both types of domains, the density of the porphyrin cores is increased in comparison to the arrangement observed on HOPG. Also, high-resolution STM images reveal that, in contrast to what is observed on HOPG, physisorption on Au(111) induces a distortion of the porphyrin macrocycle out of planarity. By using X-ray photoelectron spectroscopy, we demonstrate that this is likely to be due to the coordination of the lone pairs of the iminic (-C=N-) nitrogen atoms of the porphyrin macrocycle to Au(111). 相似文献
9.
[Structure: see text] A highly enantioselective synthesis of alpha-dehydroaminoacids with a stereogenic center in the gamma position through copper-catalyzed asymmetric conjugate addition of diethylzinc to alpha,beta-unsaturated imines using a TADDOL-derived phosphoramidite complex is reported. 相似文献
10.
We have studied the ability of an alpha-imino glyoxylamide derived from (S, S)-(+)-pseudoephedrine as a valuable chiral electrophile for the preparation of alpha-amino carbonyl compounds. In this context, the addition of Grignard reagents to the azomethine moiety of this chiral electrophile afforded the expected alpha-amino amide adducts in good yields and diastereoselectivities. Moreover, these adducts have been transformed into enantioenriched alpha-amino ketones by exploiting the ability of pseudoephedrine amides to undergo selective monoaddition to the carbamoyl group with organolithium reagents. 相似文献