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81.
Martin SR Esposito V De Los Rios P Pastore A Temussi PA 《Journal of the American Chemical Society》2008,130(30):9963-9970
Although alcohols are well-known to be protein denaturants when present at high concentrations, their effect on proteins at low concentrations is much less well characterized. In this paper, we present a study of the effects of alcohols on protein stability using Yfh1, the yeast ortholog of the human protein frataxin. Exploiting the unusual property of this protein of undergoing cold denaturation around 0 degrees C without any ad hoc destabilization, we determined the stability curve on the basis of both high and low temperature unfolding in the presence of three commonly used alcohols: trifluoroethanol, ethanol, and methanol. In all cases, we observed an extended temperature range of protein stability as determined by a modest increase of the high temperature of unfolding but an appreciable decrease in the low temperature of unfolding. On the basis of simple thermodynamic considerations, we are able to interpret the literature on the effects of alcohols on proteins and to generalize our findings. We suggest that alcohols, at low concentration and physiological pH, stabilize proteins by greatly widening the range of temperatures over which the protein is stable. Our results also clarify the molecular mechanism of the interaction and validate the current theoretical interpretation of the mechanism of cold denaturation. 相似文献
82.
B.?A.?KulikovEmail author E.?B.?Los’ N.?V.?Kulikova A.?S.?Los’ Z.?P.?Kulygina V.?V.?Malichenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(7):1115-1120
The kinetics of solution of lead fluoride crystals in water was studied under natural convection and rotating disk conditions at fixed temperatures from 0 to 80°C. The kinetic model of the process was suggested. 相似文献
83.
Relative total cross sections are reported for the production of electrons and anions in collisions between an alkali atom (Na, K, Cs) and the molecules O2 and NO. The formation of electrons is due to autoionization of vibrationally excited O2? (gu′ ? 4) respectively NO? (υ′ ? 1) molecules. The experiments have been performed with fast alkali atom beams in the laboratory energy range of 30–300 eV. 相似文献
84.
Abbott T Akiba Y Beavis D Bloomer MA Bond PD Chasman C Chen Z Chu YY Cole BA Costales JB Crawford HJ Cumming JB Debbe R Engelage J Fung SY Gushue S Hamagaki H Hansen O Hayano RS Hayashi S Homma S Huang HZ Ikeda Y Juricic I Kang J Katcoff S Kaufman S Kimura K Kitamura K Kurita K Ledoux RJ Levine MJ Miake Y Morse RJ Moskowitz B Nagamiya S Olness J Parsons CG Remsberg LP Sakurai H Sarabura M Stankus P Steadman SG Stephans GS Sugitate T Tannenbaum MJ van Dijk JH Videbaek F Vient M Vincent P 《Physical review D: Particles and fields》1992,45(11):3906-3920
85.
Luis De Los Santos V. Justin Llandro Thanos Mitrelias Thomas J. Hayward J.A.C. Bland Juan L. Arroyo C. 《Journal of magnetism and magnetic materials》2009,321(14):2129-2134
In this work, a simple technique to obtain the hysteresis loops of magnetic beads (Spherotech Inc.) in liquid suspension is presented. The magnetic measurements were taken in a DC Magnetic Property Measurement System (MPMS-SQUID sensor). Samples were based on ferromagnetic beads (surface-functionalized NH2, mean diameter 4.32 μm) prepared in three conditions: dry, suspended in sucrose solution and in suspension after functionalization with fluorophore. Special small containers (1.3 cm long) made of non magnetic plastic were designed to hold the beads in liquid. The results indicate that the bead's remnant magnetization is half of the value at maximum applied field in all cases. However, due to the additional degrees of rotational freedom, beads suspended in a liquid do not present coercivity. The use of ferromagnetic beads and magnetic elements of different architectures for applications in bioassays is also discussed. 相似文献
86.
K. Shiraishi S. Ko T. Ban-nai H. Arae K. Ayama P. V. Zamostyan N. Y. Tsigankov I. P. Los V. N. Korzun 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(2):411-415
Daily intakes of 134Cs and 137Cs in Ukrainians were estimated in relation to the health effects on habitants after the Chernobyl accident. Two hundred and
sixty-eight diet samples were collected from 25 oblasts (regions) using a duplicate portion method. For Ukrainians, the range
and median daily intakes of 137Cs were 0.53–571 and 8.8 Bq per person, respectively. Intakes of 134Cs were also detected in highly 137Cs contaminated areas. Daily intakes of 134Cs were in the range of not detected to 3.6 Bq per person. Using the highest radiocesium intakes, annual effective doses for
134Cs and 137Cs were estimated to be 2.5·10−2 and 2.7 mSv, respectively. 相似文献
87.
Lima LS Weinert PL Lemos SC Sequinel R Pezza HR Pezza L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1999-2004
This paper describes an environmentally friendly method for quantitative determination of ranitidine using diffuse reflectance spectroscopy. This method is based on the reflectance measurements of the colored product produced from the spot test reaction between ranitidine and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using filter paper as solid support. Experimental design methodologies were used to optimize the optimal conditions. All reflectance measurements were carried out at 590 nm and the linear range was from 1.42x10(-3) to 3.42x10(-2) mol L(-1), with a correlation coefficient of 0.997. The limit of detection was estimated to be 1.09x10(-3) mol L(-1) (R.S.D.=1.9%). The proposed method was successfully applied to the determination of ranitidine in commercial brands of pharmaceuticals and no interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those obtained by an official procedure at 95% confidence level. Additionally, the method was also applied to the determination of ranitidine in human urine showing excellent recoveries (99.6-100.3%). 相似文献
88.
Suleyman I. Allakhverdiev Velmurugan Thavasi Vladimir D. Kreslavski Sergey K. Zharmukhamedov Vyacheslav V. Klimov Seeram Ramakrishna Dmitry A. Los Mamoru Mimuro Hiroshi Nishihara Robert Carpentier 《Journal of Photochemistry and Photobiology, C: Photochemistry Reviews》2010,11(2-3):101-113
Among various technologies for hydrogen production, the use of oxygenic natural photosynthesis has a great potential as can use clean and cheap sources—water and solar energy. In oxygenic photosynthetic microorganisms electrons and protons produced from water and redirected by the photosynthetic electron-transport chain via ferredoxin to the hydrogen-producing enzymes hydrogenase or nitrogenase. By these enzymes, e? and H+ recombine and form molecular hydrogen. Hydrogenase activity can be very high but is extremely sensitive to the photosynthetically evolved O2 that leads to reduced and unstable H2 production. However, presently, several approaches are developed to improve the energetic efficiency to generate H2. This review examines the main available pathways to improve the photosynthetic H2 production. 相似文献
89.
J. C. De Los Reyes S. González Andrade 《Numerical Methods for Partial Differential Equations》2012,28(3):834-860
This article is devoted to the numerical simulation of time‐dependent convective Bingham flow in cavities. Motivated by a primal‐dual regularization of the stationary model, a family of regularized time‐dependent problems is introduced. Well posedness of the regularized problems is proved, and convergence of the regularized solutions to a solution of the original multiplier system is verified. For the numerical solution of each regularized multiplier system, a fully discrete approach is studied. A stable finite element approximation in space together with a second‐order backward differentiation formula for the time discretization are proposed. The discretization scheme yields a system of Newton differentiable nonlinear equations in each time step, for which a semismooth Newton algorithm is used. We present two numerical experiments to verify the main properties of the proposed approach. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011 相似文献
90.
Mildred Flores-Guerrero Luis. E. Elizalde Gladys De Los Santos-Villarreal 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):223-231
The preparation of the random photochromic copolymer poly(glycidyl methacrylate-r-1′-(2-methacryloxyethyl)-6-nitro-3′,3′-dimethylspiro-[2H-1]-benzopyran-2,2′-indoline) by ATRP is reported, which can be used for the preparation of smart materials. Narrow homopolymers obtained from glycidyl methacrylate (GMA) are prepared when HMTETA-copper bromide and ethyl 2-methyl-2-bromo-propionate are used as the catalytic system with methyl-ethyl-ketone at 50°C. By using a molar ratio of 1:1 ligand:initiator, good correlations between experimental and theoretical molecular weights and narrow molecular weight distribution are obtained. These experimental conditions are also employed for the copolymerization of GMA with a photochromic monomer, where again good control of the polymerization reaction is obtained. The copolymer is fully characterized by spectroscopic techniques. The reactivity ratios are calculated according to the extended Kelen-Tüdos method, while the composition of the copolymer is calculated by NMR. Determination of r GMA and r PHM gives a value of 0.985 for GMA and 0.596 for the photochromic monomer. 相似文献