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101.
102.
Subcellular localization patterns and their relationship to photodynamic activity of pyropheophorbide-a derivatives 总被引:7,自引:0,他引:7
MacDonald IJ Morgan J Bellnier DA Paszkiewicz GM Whitaker JE Litchfield DJ Dougherty TJ 《Photochemistry and photobiology》1999,70(5):789-797
To determine if subcellular localization is important to photodynamic therapy (PDT) efficacy, an in vitro fluorescence microscopy study was conducted with a congeneric series of pyropheophorbide-a derivatives in human pharyngeal squamous cell carcinoma (FaDu) cells and murine radiation-induced fibrosarcoma (RIF) mutant cells. In the FaDu cells the octyl, decyl and dodecyl ether derivatives localized to the lysosomes at extracellular concentrations less than needed to produce a 50% cell kill (LD50). At extracellular concentrations equal or greater than the LD50 the compounds localized mainly to mitochondria. The propyl, pentyl, hexyl and heptyl ether derivatives localized mainly to the mitochondria at all concentrations studied. This suggested that mitochondria are a sensitive PDT target for these derivatives. Similar experiments were performed with two Photofrin-PDT resistant RIF cell lines, one of which was found to be resistant to hexyl ether derivative (C6) mediated-PDT and the other sensitive to C6-PDT relative to the parent line. At extracellular concentrations of C6 below the LD50 of each cell line, the mutants exhibited lysosomal localization. At concentrations above these values the patterns shifted to a mainly mitochondrial pattern. In these cell lines mitochondrial localization also correlated with PDT sensitivity. Localization to mitochondria or lysosomes appeared to be affected by the aggregation state of the congeners, all of which are highly aggregated in aqueous medium. Monomers apparently were the active fraction of these compounds because equalizing the extracellular monomer concentrations produced equivalent intracellular concentrations, photoxicity and localization patterns. Compounds that were mainly aggregates localized to the lysosomes where they were rendered less active. Mitochondria appear to be a sensitive target for pyropheophorbide-a-mediated photodamage, and the degree of aggregation seems to be a determinant of the localization site. 相似文献
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Howard C. Haas Ruby L. MacDonald 《Journal of polymer science. Part A, Polymer chemistry》1973,11(6):1133-1140
When interpreted by network theory, equilibrium swelling measurements on poly-(vinyl chloride) (PVC) film in dioxane and moduli measurements on the equilibrium swelled films yield values for the approximate molecular weight between thermally reversible crosslinks and for the number of these crosslinks per polymer chain. These values are in reasonable agreement with the thermodynamic analysis of PVC–dioxane gels by Takahashi, Nakamura, and Kagawa and with the premise that three-dimensional network formation in these gels occurs by crystallization of a very limited number of syndiotactic sequences per chain having a sequence length of between 8 and 10. Failure to observe fusion endotherms by DTA on PVC–dibutyl phthalate gels supports the view that PVC gels have a low crystalline crosslink density and a low heat of crosslinking. The heat of crosslinking obtained by the method of Eldridge and Ferry shows only moderate agreement with expectations based on the heat of fusion of PVC and the number of repeating units per PVC chain passing through a crystalline crosslink in a PVC–dioxane gel. 相似文献
105.
J M Midgley R Andrew D G Watson N MacDonald J L Reid D A Williams 《Journal of chromatography. A》1990,527(2):259-265
Dichlorotetrafluoroacetone has been used to prepare 4-substituted 2-bis (chlorodifluoromethyl)-1,3-dioxolan-5-one derivatives of mandelic acids which were found to be suitable for the analysis of these compounds by gas chromatography-negative-ion chemical ionisation mass spectrometry (GC-NICIMS). The high specificity of the derivatising agent facilitates the identification and quantitation of small amounts of mandelic acids in complex biological matrices. The derivatisation procedure was used to determine the concentrations of m- and p-hydroxymandelic acids and vanillylmandelic acid in to the urine of normal subjects. The method may also have application in the determination of isomeric phenylethylene glycols, the corresponding products of reductive metabolism of biogenic amines. 相似文献
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Howard C. Haas Ruby L. MacDonald Alan N. Schuler 《Journal of polymer science. Part A, Polymer chemistry》1970,8(12):3405-3415
Forming and conditioning thermally reversible aqueous gels of polyacrylyglycinamide (PAG) at various temperatures has little effect on either the melting point (Tm) of the gels or the heat of crosslinking (ΔHc) except at temperatures where partial hydrolysis can occur. This is added evidence that unlike with gelatin, crystallite formation does not play a role in gel formation. For unfractioned PAG, the linear relationship between the logarithm of molecular weight and 1/Tm predicted and observed for gelatin gels, does not hold. With mixed gelatin-PAG gels, a gelatin/PAG ratio of ≥4 completely inhibits the formation of a PAG gel network. At lower gelatin/PAG ratios, the PAG network forms, and if gelatin is considered as an inert diluent, normal values for the melting points and ΔHc for PAG gels are observed. At a gelatin/PAG ratio of 4, the presence of PAG reduces the ΔHc for the gelatin gel by inhibiting the formation of as large or as ordered crystallite crosslinks. To reconcile the problem of aggregation preceding gelation one can assume that M?w of an aggregate is a linear function of C2. If this is done, the same relationship which normally relates C with Tm is obtained. The equilibrium swelling of PAG films in water at 25°C is markedly molecular weight-de-pendent and can vary from below 5 to about 40 wt-% polymer at equilibrium. It has been found that long-term dark storage of dry samples of PAG under ambient temperature conditions results in pronounced decreases in the intrinsic viscosities of their aqueous solutions. It is speculated that this results from weak links, perhaps peroxy, in the polymer backbone. The possible relationship of this phenomenon to the slow stage of the viscosity deterioration of aqueous polyacrylamide solutions is pointed out. The higher viscosity of low DP PAG in 2M NaCNS compared to H2O and the larger percentage increse of [η] with increasing temperature in the latter, verify the greater solvent power of 2M aqueous thiocyanate for PAG. At a concentration level of 3%, aqueous PAG solutions are almost Newtonian whereas at higher concentrations (5%), the viscosity decreases appreciably with increasing rates of shear. The copolymerization of AG with isopropylacrylamide has been studied and the somewhat unusual results discussed. Copolymers containing an AG mole fraction greater than 0.40 do not exhibit a cloud point up to 100°C. If the isopropylacrylamide mole fraction approaches 0.60, the solutions do not gel down to 0°C. This ability to prepare copolymers over a narrow composition range that neither gel or undergo phase separation in the temperature range 0–100°C is probably related to the random distribution of monomer units in the copolymer backbone. 相似文献