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11.
Elena V. Parfenyuk Olga I. Davydova Nataliya Sh. Lebedeva 《Journal of solution chemistry》2004,33(1):1-10
Calorimetric titrations have been performed at 298.15 K in aqueous solutions to derive the stability constants and thermodynamic parameters of the interactions of D-maltose and sucrose with some amino acids (glycine, DL-alanine, DL-leucine, and L-serine). The apparent molal volumes of the disaccharides in dilute aqueous solutions of the amino acids have been determined from density measurements at 298.15 K. In contrast to D-maltose, sucrose was found to associate with the amino acids and these associated species are preferentially entropy stabilized. These results are interpreted in terms of the influence of the nature of the solutes, their specific conformations, and hydration, on the ability of the disaccharides to form associated complexes with the amino acids. 相似文献
12.
E. V. Ivanov E. Yu. Lebedeva V. K. Abrosimov N. G. Ivanova 《Russian Chemical Bulletin》2004,53(4):751-757
Densities of Bun
4NBr solutions in MeOH, MeOD, and CD3OH were measured at salt concentrations of up to 1.5 solvomolality units (nearly 2.63·10–2 mole fraction) at 278.15, 288.15, 298.15, 308.15, and 318.15 K. The limiting partial molar volumes of Bun
4NBr dissolved in these alcohols were calculated. The isotope effects in the volume characteristics of the stoichiometric mixture of ions, [Bun
4N+ + Br–], are mainly due to the vibrational changes in the solvent structure upon deuteration of different molecular fragments. Structural transformations in infinitely dilute solution of Bun
4NBr in methanol are governed by non-specific solvation of the symmetrical Bun
4N+ cation. 相似文献
13.
G. F. Lebedeva T. Ya. Yarkova V. V. Platonov V. A. Proskuryakov 《Russian Journal of Applied Chemistry》2005,78(8):1360-1363
The possibility of chemical modification of peat humic acids in order to increase their bioactivity by reduction with tin(II) chloride and sodium borohydride and also by carboxylation using the Kolbe method was analyzed. 相似文献
14.
Siberian Technological Institute, Krasnoyarsk. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 423–424, May–June, 1991. 相似文献
15.
Comparative study of photodynamic properties of 13,15-N-cycloimide derivatives of chlorin p6 总被引:1,自引:0,他引:1
Feofanov A Sharonov G Grichine A Karmakova T Pljutinskaya A Lebedeva V Ruziyev R Yakubovskaya R Mironov A Refregier M Maurizot JC Vigny P 《Photochemistry and photobiology》2004,79(2):172-188
Comparative study of 13,15-[N-(2-hydroxyethyl)]cycloimide chlorin p6 (2), 13,15-(N-acetoxy)cycloimide chlorin p6 (3), 13,15-(N-hydroxy)cycloimide chlorin p6 methyl ester (4) and 13,15-(N-methoxy)cycloimide chlorin p6 methyl ester (5) together with the previously investigated 13,15-[N-(3-hydroxypropyl)]cycloimide chlorin p6 (1) was performed. The dependence of the key photodynamic properties of 1-5 on the introduced substituents was analyzed. The photoinduced cell-killing activity of 4 is 100- and 280-fold higher than that of chlorin p6 and Photogem, respectively, as estimated on A549 human lung adenocarcinoma cells. The activity is reduced eight times in the order 4 > 5 > 1 > 2 > 3. The intracellular accumulation of 1-5 occurs in cytoplasm in a monomeric form bound to the lipids of cellular membranes. This form of 1, 2, 3, 4 and 5 is characterized by the high quantum yield of singlet oxygen generation, which depends on the introduced substituents, 0.66, 0.59, 0.35, 0.51 and 0.73, respectively. The photostability is two-fold less for 1 and four-fold less for 2, 3 and 5 than for 4. The rates of cellular uptake and efflux of 1-5 vary widely, thus providing the way to optimize the pharmacological properties of the photosensitizer (PS) using the respective substituents. Modifying the substituents, 1-5 were targeted to different cellular organelles. The enhanced accumulation in the Golgi apparatus and mitochondria complemented with diffuse staining of intracellular membranous structures is a property of 1-4. Compound 5 accumulates selectively in the lipid droplets and stains weakly perinuclear structures. Temperature-sensitive mechanisms of transport are responsible for the 1-4 uptake. Diffusion can play a role in the internalization of 5 but not of 1-4. Endocytosis via caveolae, clathrin-dependent and adenosine triphosphate-dependent pathways are not noticeably involved in the 1-5 internalization. Independently from their intracellular localization 1, 4 and 5 are highly efficient near-IR PS, which induce predominantly an apoptotic type of cell death under conditions providing ca 50% level of phototoxicity and necrosis at the 100% level of phototoxicity. 相似文献
16.
A. G. Seleznev V. M. Radchenko V. D. Shushakov M. A. Ryabinin R. R. Droznik L. S. Lebedeva V. Ya. Vasilyev 《Journal of Radioanalytical and Nuclear Chemistry》1990,143(1):253-259
248Cm and249Bk metals were prepared by thermal reduction of their oxides with thorium and metallic249Cf with metallic lanthanum. These rare actinide samples of 1.0 mg in mass were thin layers on a flat substrate and were investigated by X-ray technique. Dhcp lattice parameters of -Cm, -Bk and -Cf as main phases in X-ray diagrams are presented. The effect of impurities on the -Cm lattice parameters is shown. Fcc lattices for the high temperature form of Cm metal (-Cm) with a=0.4933 nm, and of Cm and Bk monoxides (a=0.502–0.504 nm and a=0.5002 nm, respectively) have been observed. Thermal expansion coefficients for -Cm and -Bk at 80–300 K were calculated. Identification problems of fcc lattices and oxidation features of metals prepared are discussed. 相似文献
17.
I. S. Kalashnikova T. L. Lebedeva A. A. Grechnikov N. A. Plate B. F. Myasoedov 《Journal of Analytical Chemistry》2002,57(5):399-406
The mechanism of the sorption of 1,1-dimethylhydrazine vapors with metal chloride complexes of poly-(N-2-R-oxycarbonylethyl)-ethyleneimines (R = –n-C4H9, –n-C10H21) was studied by Fourier transform IR spectroscopy (FTIR) and piezoelectric resonance. The structure of the products was determined. This allowed for the optimization of the chemical composition and structure of poly-(N-2-R-oxycarbonylethyl)-ethyleneimine-based complexes in their use as sensitive coatings of piezoelectric sensors for determining 1,1-dimethylhydrazine vapors in air. 相似文献
18.
N. Sh. Lebedeva R. S. Kumeev G. A. Al’per E. V. Parfenyuk A. S. Vashurin T. V. Tararykina 《Journal of solution chemistry》2007,36(6):793-801
For the first time the interactions between zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine (Zn(4—O—CO—C6H4—OC11H23)Pc) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in o-xylene and chloroform have been studied by calorimetric titration and NMR and electron absorption spectroscopic methods.
It has been found that in o-xylene at concentrations of Zn(4—O—CO—C6H4—OC11H23)Pc higher than 6×10−4 mol⋅L−1
π–π dimers species are formed (λ
max= 685 nm). Additions of DABCO to the solution up to mole ratio 1 : 8 (Zn(4—O—CO—C6H4—OC11H23)Pc : DABCO) lead to a shift of the aggregation equilibrium towards monomer species due to formation of monoligand axial complexes.
Further increasing the DABCO concentration results in formation of Zn(4—O—CO—C6H4—OC11H23)Pc—DABCO—Zn(4—O—CO—C6H4—OC11H23)Pc sandwich dimers (λ
max= 675 nm). 相似文献
19.
E.M. Akulonok V.Ya. Khaimov-Malkov Yu.K. Danileiko A.A. Manenkov V.S. Nechitailo T.P. Lebedeva 《Journal of solid state chemistry》1978,26(1):17-25
A problem of trap diffusion, that is diffusion of point defects in crystals participating in a solid-phase chemical reaction with motionless impurity ions, is solved. Time dependences of the reaction-front displacement, Xf, and its steepness, are determined analytically for N0 ? C0 and numerically for all relations of N0 and C0where C0 and N0 are the initial concentration of impurity and the eqilibrium defect concentration, respectively, D is a diffusion coefficient, and g is a chemical reaction constant. Dependence of Xf vs C0 and t is confirmed for oxygen annealing of corundum crystals doped with titanium which, reacting with the point defects, changes its valency. The data are obtained for dependence of displacement Xf upon partial oxygen pressure and thermotreatment temperature as well as upon the sign of the constant electric field applied to the sample. From these data we conclude that the reaction of titanium impurity, changing from the three-valent to the tetravalent state at the activation energy of 80 ± 8.5 kcal/mole is due to anisotropic diffusion of charged aluminum vacancy and holes in the valence band. The diffusion coefficient for that process at 1500°C is estimated to be larger than 10?5 cm2/sec. Using the trap-diffusion features, the concentration of optical centers of the 0.315-μm absorption band in ruby is also estimated. 相似文献
20.
Yu. V. Markova N. G. Ostroumova V. I. Lebedeva M. N. Shchukina 《Chemistry of Heterocyclic Compounds》1970,6(3):385-388
The condensation of urethane and ethyl acetohydroximate with 2-chloromethyl-1-methylbenzimidazole has given, respectively, N-ethoxycarbonyl-O-(1-methylbenzimidazol-2-ylmethyl)hydroxylamine and ethyl N-(1-methylbenzimidazol-2-ylmethoxy)acetimidate. Acid hydrolysis of the latter has given O-(1-methylbenzimidazol-2-ylmethyl)hydroxylamine. The reactions of its derivatives with HCl have been studied, and it has been shown that 1-methylbenzimidazole-2-aldehyde O-(1-methylbenzimidazole-2-methyl)oxime is formed. The structure of the latter has been shown by an analysis of its PMR spectra.For part II, see ¦1¦. 相似文献