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101.
Nath A Koo PK Rhoades E Atkins WM 《Journal of the American Chemical Society》2008,130(47):15746-15747
Cytochrome P450 (CYP) 3A4 is a major human drug-metabolizing enzyme and displays pharmacologically relevant allosteric kinetics caused by multiple substrate and/or effector binding. Here, in the first single-molecule (SM) fluorescence studies of CYPs, we use total internal reflection fluorescence microscopy to measure residence times of the fluorescent dye Nile Red in CYP3A4 incorporated in surface-immobilized lipid Nanodiscs, with and without the effector alpha-naphthoflavone. We find direct evidence that CYP3A4 effectors can decrease substrate off-rates, providing a possible mechanism for effector-mediated enhancement of substrate metabolism. These interesting results highlight the potential of SM methods in studies of CYP allosteric mechanisms. 相似文献
102.
H. Maheswaran P.J. Amal Joseph K. Leon Prasanth S. Priyadarshini P. Satyanarayana Praveen R. Likhar M. Lakshmi Kantam 《Tetrahedron: Asymmetry》2010,21(17):2158-2166
The use of structurally well-defined chiral [CuCl2(sparteine)] 1 and [NiCl2(sparteine)] 2 complexes as catalysts under fluoride anion-promoted double catalytic activation (DCA) conditions cause enantioreversal in the asymmetric Mukaiyama aldol reaction of 1-phenyl-1-trimethylsiloxyethylene with various aromatic aldehydes. A similar enantioreversal also occurs in the direct aldol reaction between methyl vinyl ketone and various aromatic aldehydes under Et3N promoted DCA conditions. We have quantitatively analyzed using group theoretical analysis via symmetry deformation coordinates, the molecular structures of 1 and 2 from the X-ray structural data; the results from the study show that the innate stereochemical differences that are present in their molecular structures, form the basis for the enantioreversal phenomenon in the asymmetric C–C bond-forming aldol reactions. 相似文献
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104.
Pottabathula Srinivas Pravin R. Likhar Dr. Hariharasarma Maheswaran Dr. Balasubramanian Sridhar Dr. Krishnan Ravikumar Dr. Mannepalli Lakshmi Kantam Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(7):1578-1581
Structurally well defined and thermally stable PdII complexes, derived from N4‐tetradentate dicarboxyamide/dipyridyl ligands, were evaluated as catalysts for the Heck reactions of deactivated aryl chlorides and olefins (see scheme). The concept of using an anionic carboxyamide as an ancillary ligand for palladium demonstrated here provides a new opportunity for the development of phosphine‐free transition‐metal catalysis.
105.
Maheswaran H Prasanth KL Krishna GG Ravikumar K Sridhar B Kantam ML 《Chemical communications (Cambridge, England)》2006,(39):4066-4068
The dichloro[(-)-sparteine-N,N']copper(II) complex provides Henry adducts with high enantioselectivities (73-97% ee) in Henry reaction between nitromethane and various aldehydes. 相似文献
106.
Tania Konry Shyam Sundhar Bale Abhinav Bhushan Keyue Shen Erkin Seker Boris Polyak Martin Yarmush 《Mikrochimica acta》2012,176(3-4):251-269
There is a growing need for diagnostic technologies that provide laboratories with solutions that improve quality, enhance laboratory system productivity, and provide accurate detection of a broad range of infectious diseases and cancers. Recent advances in micro- and nanoscience and engineering, in particular in the areas of particles and microfluidic technologies, have advanced the “lab-on-a-chip” concept towards the development of a new generation of point-of-care diagnostic devices that could significantly enhance test sensitivity and speed. In this review, we will discuss many of the recent advances in microfluidics and particle technologies with an eye towards merging these two technologies for application in medical diagnostics. Although the potential diagnostic applications are virtually unlimited, the most important applications are foreseen in the areas of biomarker research, cancer diagnosis, and detection of infectious microorganisms. Figure
There is a growing need for diagnostic technologies that provide laboratories with solutions that improve quality, enhance laboratory system productivity, and provide accurate detection of a broad range of infectious diseases and cancers. In this review, we will discuss many of the recent advances in microfluidics and particle technologies with an eye towards merging these two technologies for application in medical diagnostics such as microfluidic device to monitor molecular secretions in real-time as demonstrated in this figure. 相似文献
107.
The diamond like carbon (DLC) films have been grown by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) in methane-argon plasma. In PECVD, the plasma sheath potential drop arising due to argon plasma was utilized to grow the DLC film on silicon (100) substrate at low temperature without using any external negative bias voltage. The growth process of the DLC film has been studied completely starting from nucleation to continuous film by atomic force microscopy. It was seen that the DLC film nucleates around surface defects on the substrate and that the film growth occurs by both adatom deposition and coalescence between nucleated islands. Raman spectrum confirms that the DLC film nucleates excessively in sp2 hybridized state and that during the growth process the fraction of sp3 CHx (x = 1 − 3) increases which leads to the amorphous nature of the film. Long range uniformity of the film was identified using scanning electron microscope. 相似文献
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110.
Radhey M. Naik Abhinav Agarwal Amit K. Verma Shiv Bali S. Yadav Basant Kumar 《国际化学动力学杂志》2009,41(4):215-226
The kinetics and mechanism of Hg2+‐catalyzed substitution of cyanide ion in an octahedral hexacyanoruthenate(II) complex by nitroso‐R‐salt have been studied spectrophotometrically at 525 nm (λmax of the purple‐red–colored complex). The reaction conditions were: temperature = 45.0 ± 0.1°C, pH = 7.00 ± 0.02, and ionic strength (I) = 0.1 M (KCl). The reaction exhibited a first‐order dependence on [nitroso‐R‐salt] and a variable order dependence on [Ru(CN)64?]. The initial rates were obtained from slopes of absorbance versus time plots. The rate of reaction was found to initially increase linearly with [nitroso‐R‐salt], and finally decrease at [nitroso‐R‐salt] = 3.50 × 10?4 M. The effects of variation of pH, ionic strength, concentration of catalyst, and temperature on the reaction rate were also studied and explained in detail. The values of k2 and activation parameters for catalyzed reaction were found to be 7.68 × 10?4 s?1 and Ea = 49.56 ± 0.091 kJ mol?1, ΔH≠ = 46.91 ± 0.036 kJ mol?1, ΔS≠ = ?234.13 ± 1.12 J K?1 mol?1, respectively. These activation parameters along with other experimental observations supported the solvent assisted interchange dissociative (Id) mechanism for the reaction. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 215–226, 2009 相似文献