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1.
Edwige Jeanneau-Nicolle Claude Bosso Martine Benoit-Guyod Grard Leclerc 《Journal of mass spectrometry : JMS》1993,28(1):37-41
The electron impact mass spectra of two series of 5-oxo-tetrahydro-5H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates and 7-oxo-tetrahydro-7H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates were measured and fragmentation patterns examined. Structures were assigned from analysis of oxo molecular ion fragmentations. Compounds of the 5-oxo series gave an [M – CO2C2H5]+ fragmentation whereas compounds of the 7-oxo series gave three characteristic cleavages. This decomposition was confirmed for one pair of isomers by high-resolution mass spectrometry and unimolecular mass-analysed ion kinetic energy spectrometry. Electron impact mass spectrometry is a convenient method for assigning structures of 5- and 7-oxo regioisomers of tetrahydrothiazolo[3,2-a]pyrimidine-6-carboxylates. 相似文献
2.
Matthias Bhm Edwige Lorthiois Muthuppalaniappan Meyyappan Andrea Vasella 《Helvetica chimica acta》2003,86(11):3787-3817
Racemic and enantiomerically pure manno‐configured isoquinuclidines were synthesized and tested as glycosidase inhibitors. The racemic key isoquinuclidine intermediate was prepared in high yield by a cycloaddition (tandem Michael addition/aldolisation) of the 3‐hydroxy‐1‐tosyl‐pyridone 10 to methyl acrylate, and transformed to the racemic N‐benzyl manno‐isoquinuclidine 2 and the N‐unsubstituted manno‐isoquinuclidine 3 (twelve steps; ca. 11% from 10 ). Catalysis by quinine of the analogous cycloaddition of 10 to (?)‐8‐phenylmenthyl acrylate provided a single diastereoisomer in high yield, which was transformed to the desired enantiomerically pure D ‐manno‐isoquinuclidines (+)‐ 2 and (+)‐ 3 (twelve steps; 23% from 10 ). The enantiomers (?)‐ 2 and (?)‐ 3 were prepared by using a quinidine‐promoted cycloaddition of 10 to the enantiomeric (+)‐8‐phenylmenthyl acrylate. The N‐benzyl D ‐manno‐isoquinuclidine (+)‐ 2 is a selective and slow inhibitor of snail β‐mannosidase. Its inhibition strength and type depends on the pH (at pH 4.5: Ki=1.0 μM , mixed type, α=1.9; at pH 5.5: Ki=0.63 μM , mixed type, α=17). The N‐unsubstituted D ‐manno‐isoquinuclidine (+)‐ 3 is a poor inhibitor. Its inhibition strength and type also depend on the pH (at pH 4.5: Ki=1.2?103 μM , mixed type, α=1.1; at pH 5.5: Ki=0.25?103 μM , mixed type, α=11). The enantiomeric N‐benzyl L ‐manno‐isoquinuclidine (?)‐ 2 is a good inhibitor of snail β‐mannosidase, albeit noncompetitive (at pH 4.5: Ki=69 μM ). The N‐unsubstituted isoquinuclidine (?)‐ 2 is a poor inhibitor (at pH 4.5: IC50=7.3?103 μM ). A comparison of the inhibition by the pure manno‐isoquinuclidines (+)‐ 2 and (+)‐ 3 , (+)‐ 2 /(?)‐ 2 1 : 1, and (+)‐ 3 /(?)‐ 3 1 : 1 with the published data for racemic 2 and 3 led to a rectification of the published data. The inhibition of snail β‐mannosidase by the isoquinuclidines 2 and 3 suggests that the hydrolysis of β‐D ‐mannopyranosides by snail β‐mannosidase proceeds via a distorted conformer, in agreement with the principle of stereoelectronic control. 相似文献
3.
Iqra Bano Pavel Horky Syed Qamar Abbas Muhammad Majid Akram Hafiz Muhammad Bilal Fawad Ali Tapan Behl Syed Shams ul Hassan Simona Bungau 《Molecules (Basel, Switzerland)》2022,27(7)
Ferroptosis is a recently described programmed cell death mechanism that is characterized by the buildup of iron (Fe)-dependent lipid peroxides in cells and is morphologically, biochemically, and genetically distinct from other forms of cell death, having emerged to play an important role in cancer biology. Ferroptosis has significant importance during cancer treatment because of the combination of factors, including suppression of the glutathione peroxidase 4 (Gpx4), cysteine deficiency, and arachidonoyl (AA) peroxidation, which cause cells to undergo ferroptosis. However, the physiological significance of ferroptosis throughout development is still not fully understood. This current review is focused on the factors and molecular mechanisms with the diagrammatic illustrations of ferroptosis that have a role in the initiation and sensitivity of ferroptosis in various malignancies. This knowledge will open a new road for research in oncology and cancer management. 相似文献
4.
Edwige Croix 《Comptes Rendus Mathematique》2006,343(5):303-306
The author proves that any ideal generated by a finite number of real analytic functions in an intersection of non-quasi-analytic classes is closed for the natural Frechet topology associated to such a space. She also establishes a closedness criterion when the generators are less regular. To cite this article: E. Croix, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
5.
Tiberiu-M. Gianga Edwige Audibert Anamaria Trandafir Gabriele Kociok-Khn G. Dan Panto 《Chemical science》2020,11(35):9685
We report herein the first all-donor aromatic [2]catenane formed through dynamic combinatorial chemistry, using single component libraries. The building block is a benzo[1,2-b:4,5-b′]dithiophene derivative, a π-donor molecule, with cysteine appendages that allow for disulfide exchange. The hydrophobic effect plays an essential role in the formation of the all-donor [2]catenane. The design of the building block allows the formation of a quasi-fused pentacyclic core, which enhances the stacking interactions between the cores. The [2]catenane has chiro-optical and fluorescent properties, being also the first known DCC-disulphide-based interlocked molecule to be fluorescent.An all-donor [2]catenane has been synthesised via dynamic combinatorial chemistry. It features stacked benzodithiophenes which are quasi-pentacyclic through hydrogen bonding. 相似文献
6.
Shahid Iqbal Gulzar Hameed Arjamand Bano 《Journal of Dispersion Science and Technology》2013,34(11):1618-1628
Theory regarding emulsification, its coalescence and impact of emulsifier over its stability has been updated. For the verification of the proposed theory, water-in-oil emulsion was prepared by mixing water and soybean oil in the presence and absence of emulsifier, monoglyceride. The effect of different parameters like emulsification time, contents of water, and concentration of emulsifier has been investigated on the emulsification and coalescence process of the emulsion. It was noted that the emulsion quality was highest if the mixture was homogenized for about 15 minutes and the water contents were 40% v/v. The addition of monoglyceride up to 0.5% w/v gave the most stable emulsion having higher quality than other composition. The results obtained were compared with the proposed theory and found to have good compositions. 相似文献
7.
The kinetics of a triarylmethane dye, brilliant green (BG), by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) was studied spectrophotometrically in HClO4 media at 303 K. Under identical experimental conditions, the rate law was ?d [BG]/dt = k [BG] [H+]. Variations in ionic strength (μ) of the medium had no effect on the oxidation velocity. Addition of p-toluenesulfonamide, the reduction product of CAT and Cl?, had no significant effect on the rate of reaction. The values of rate constants observed at five different temperatures (298, 303, 308, 313, and 318 K) were utilized to calculate the activation parameters. The observed results have been explained by a general mechanism and the related rate law has been obtained. The process demonstrated in this study is cost effective, which holds great promise in potential application for pollutant control. 相似文献
8.
Shaheen Faizi Humaira Siddiqi Aneela Naz Samina Bano Lubna 《Helvetica chimica acta》2010,93(3):466-481
An H/D exchange process in patuletin ( 1 ) and its derivatives in D‐donor solvents (e.g., CF3COOD), which occurs regioselectively at C(8) was observed for the first time during NMR studies. The effect of substituents and temperature on the deuteration of various flavonoids (see Fig. 1) which include apigenin, chrysin, galangin, kaempferol, luteolin, morin, myricetin, patuletin, patulitrin, and quercetin, as well as derivatives of patuletin was examined extensively under NMR conditions. The rate constant of deuteration at C(8) of patuletin ( 1 ) and two flavones, luteolin ( 3 ) and apigenin ( 12 ), was also determined in CF3COOD. The D‐atom was introduced into the flavonoids via a keto–enol tautomerism (Scheme 1). During these studies, monodeuterated patuletin was also obtained as a new compound. The examined flavonoids have been reported to possess significant pharmacological activities, and their deuterated derivatives would be of importance for the identification and quantification of these compounds in biological matrices. 相似文献
9.
Vijay K. Agrawal Shahnaz Bano Keshav C. Mathur Padmakar V. Khadikar 《Journal of Chemical Sciences》2000,112(2):137-146
The paper gives a brief account of the recently introduced Szeged index (Sz). Using this index antitubercular activities of
N-2,4-difluorophenyl quinolones are subjected to quantitative structure-activity relationship analysis. The potential of Sz
related to the Wiener index (W) is critically discussed. In addition, Huckel molecular orbital energies:E
HOMO,E
LUMO andE
total were also used for comparing and modelling antitubercular activities of the quinolones. The results, based on univariate
as well as multivariate regressions, have shown that W, SZ andE
total give better results and that the correlations improve in multivariate regression analyses. 相似文献
10.
Mannini M Tancini E Sorace L Sainctavit P Arrio MA Qian Y Otero E Chiappe D Margheriti L Cezar JC Sessoli R Cornia A 《Inorganic chemistry》2011,50(7):2911-2917
Surface-supported arrays of Fe(4)-type Single-Molecule Magnets retain a memory effect and are of current interest in the frame of molecule-based information storage and spintronics. To reveal the spin structure of [Fe(4)(L)(2)(dpm)(6)] (1) on Au, an isomorphous compound [Fe(3)Cr(L)(2)(dpm)(6)] was synthesized and structurally and magnetically characterized (H(3)L is tripodal ligand 11-(acetylthio)-2,2-bis(hydroxymethyl)undecan-1-ol and Hdpm is dipivaloylmethane). The new complex contains a central Cr(3+) ion and has a S = 6 ground state as opposed to S = 5 in 1. Low-temperature X-ray Magnetic Circular Dichroism studies at Fe- and Cr-L(2,3) edges revealed that the antiparallel alignment between Fe and Cr spins is preserved on surfaces. Moreover, the different Fe-L(2,3) spectral features found in the homo- and heterometallic species disclose the opposing contribution of the central Fe(3+) ion in the former compound, proving that its ferrimagnetic spin structure is retained on surfaces. 相似文献