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101.
Douglas A. Smith Douglas A. Smith S. Vijayakumar 《Journal of computational chemistry》1993,14(11):1313-1319
The limiting factor to account for the increased rate of intramolecular reactions between functional groups as opposed to their intermolecular counterparts can and has been explained both by proximity effects and by activation energy. Neither explanation has emerged as the single most important reason in all or even the majority of cases studied. We have therefore reexamined the spatiotemporal hypothesis of Menger and the transition-state energy approach of Houk on a consistent set of compounds subjected to the Barton oxidation or related reactions in an effort to more clearly define the reasons for the proximity effect. For the 26 structures studied, neither hypothesis provides a consistent, quantitative explanation although the transitionstate energy hypothesis offered the most promise. © John Wiley & Sons, Inc. 相似文献
102.
Balasubramaniyam Arul Prakasam Kuppukkannu Ramalingam Gabriele Bocelli Andrea Cantoni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):2020-2033
The current article describes the TG and DT analyses of divalent Zn, Cd, and Hg dithiocarbamato (dtc) complexes and their adducts (dchdtc = N,N-dicyclohexyldithiocarbamate anion, 4-mpzdtc = 4-methylpiperazinecarbodithioato anion, padtc = N,N′-(iminodiethylene)bisphthalimidedithiocarbamate anion, pipdtc = piperidinecarbodithioate anion, 1,10-phen = 1,10-phenanthroline, and 2,2′-bipy = 2,2′-bipyridine) along with the structural reinvestigation of [Hg(tetds)I 2 ], where tetds = tetraethylthiuramdisulfide. In the case of Zn(II) and Cd(II) dithiocarbamates and their nitrogenous adducts, thermal decomposition of the nitrogenous bases is followed by the decay of dithiocarbamate leading to the formation of ZnS or CdS as residue. The interaction of iodine with [Hg(dedtc) 2 ] in CHCl 3 results in the oxidation of diethyldithiocarbamate leading to the formation of [Hg(tetds)I 2 ], and the structure was redetermined because the earlier determination was by a Polaroid crystallographic technique with a higher R value. The S-Hg-I bond angles [105.09(3); 105.59(3); 109.26(3), and 100.99(3)°] indicate the near tetrahedral environment around the metal ion. 1 H and 13 C NMR spectra of the complex were analyzed. Whether the product formed upon oxidation is a disulfide or an iodo-substituted product, in the present investigation, is clearly decided by the bulkiness of the substituent attached to the nitrogen. Interestingly, the steric influence is a deciding factor only in the case of mercury compounds and the dithiocarbamates involving Zn, Cd forms of the disulfide complexes. 相似文献
103.
Prof. Dr. Sunney I. Chan Yu‐Jhang Lu Dr. Penumaka Nagababu Dr. Suman Maji Mu‐Cheng Hung Marianne M. Lee Prof. Dr. I‐Jui Hsu Pham Dinh Minh Jeff C.‐H. Lai Kok Yoah Ng Sridevi Ramalingam Prof. Dr. Steve S.‐F. Yu Prof. Dr. Michael K. Chan 《Angewandte Chemie (International ed. in English)》2013,52(13):3731-3735
104.
Sathya Vijayakumar Deepa Appadurai Sangeetha Lakshmi Kandhan Srinivasadesikan Venkatesan Lee Shyi-Long Padmini Vediappen 《Journal of fluorescence》2022,32(4):1389-1396
Merocyanine dye based fluorescent organic compound has been synthesized for the detection of glutamine. The probe showed remarkable fluorescent intensity with glutamine through ICT (Intermolecular Charge Transfer Mechanism). Hence, it is tested for the detection of glutamine using colorimetric and fluorimetric techniques in physiological and neutral pH (7.2). Under optimized experimental conditions, the probe detects glutamine selectively among other interfering biomolecules. The probe has showed a LOD (lower limit of detection) of 9.6?×?10–8 mol/L at the linear range 0–180 µM towards glutamine. The practical application of the probe is successfully tested in human biofluids.
Graphical abstract 相似文献105.
106.
S. Meenakshi V. Vijayakumar S.N. Achary 《Journal of Physics and Chemistry of Solids》2011,72(6):609-612
The results of high-pressure angle dispersive X-ray diffraction measurements up to 34.3 GPa on the double perovskite Ba2MgWO6 are presented. The ambient rock salt phase (SG: Fm-3m) is found to be stable up to the highest pressure of the present measurements. The third order Birch-Murnaghan equation of state when fitted to pressure-volume data, yielded a zero pressure bulk modulus (B0),and its first and second pressure derivatives as 137.0(81) GPa, and 3.9(5) and −0.03 GPa−1, respectively. 相似文献
107.
Chinnaswamy Thangavel Vijayakumar Palanichamy Sivasamy 《European Polymer Journal》2007,43(7):3028-3035
Polyesterification of adipic acid and maleic anhydride with 1,3-bis(2-hydroxyethoxy)benzene (HER) in the presence of toluene-4-sulphonic acid was carried out using melt condensation technique. The structural characterization of the synthesized polyesters had been carried out using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopic methods. The thermal properties of the polyesters were studied using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The activation energies for the thermal degradation of the polyesters were calculated by the method of Dharwadkar and Kharkhanavala and discussed. The char residue value at 600 °C indicated maleic anhydride based polyester is thermally more stable compared to the adipic acid based polyester. The mechanism of degradation of these polyesters is discussed. 相似文献
108.
109.
110.
Structural Chemistry - G-protein–coupled receptors are integral membrane proteins involved in signal transduction pathways, making them an appealing drug targets for a wide spectrum of... 相似文献