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Wang MF Liao YF Hung YC Lin CL Hour TC Lue KH Hung HC Liu GY 《Experimental & molecular medicine》2011,43(4):189-196
Ornithine decarboxylase (ODC) is the rate-limiting enzyme in polyamine biosynthesis and a target for chemoprevention. Hydroxydibenzoylmethane (HDB), a derivative of dibenzoylmethane of licorice, is a promising chemopreventive agent. In this paper, we investigated whether HDB would inhibit the ODC pathway to enhance apoptosis in human promyelocytic leukemia HL-60 cells. We found ODC enzyme activity was reduced during HDB treatment. Overexpression of ODC in HL-60 parental cells could reduce HDB-induced apoptosis, which leads to loss of mitochondrial membrane potential (Δψ(m)), through lessening intracellular ROS. Furthermore, ODC overexpression protected cytochrome c release and the activation of caspase-3 following HDB treatment. The results demonstrated HDB-induced apoptosis was through a mechanism of down-regulation of ODC and occurred along a ROS-dependent mitochondria-mediated pathway. 相似文献
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Aqueous solutions of charged spherical macroions with variable dielectric permittivity and their associated counterions are examined within the cell model using a field theory and Monte Carlo simulations. The field theory is based on separation of fields into short- and long-wavelength terms, which are subjected to different statistical-mechanical treatments. The simulations were performed by using a new, accurate, and fast algorithm for numerical evaluation of the electrostatic polarization interaction. The field theory provides counterion distributions outside a macroion in good agreement with the simulation results over the full range from weak to strong electrostatic coupling. A low-dielectric macroion leads to a displacement of the counterions away from the macroion. 相似文献
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The permeant states of various solvents in poly(dimethyl siloxane) (PDMS) film were evaluated using low temperature differential scanning calorirnetry (DSC) on both vapor and liquid penetrants. Water, cyclohexane, benzene, toluene, and m‐xylene may be present in the freezable and nonfreezable state. At low sorption levels, solvents sorbed in PDMS were in the nonfreezable state until a threshold value was reached. Beyond that, the increased solvent sorption values all occurred in a freezable state. The partition pattern between the freezable and nonfreezable states for a vapor penetrant showed an identical trend with that for the liquid penetrant. The maximum nonfreezable amount of solvent in PDMS depended on the solvent's chemical compatibility with the membrane but not on the sorption temperature. Compared with that at 10°C, the higher solvent solubility at 25°C was due to the increase in the freezable solvent content without any change in the maximum nonfreezable content. The permeant states for equilibrium and nonequilibrium samples did not differ from one another. 相似文献
25.
Dong Ruan Ang Lue Jinping Zhou Hui Chen Xuming Chen Benjamin Chu Tetsuo Kondo 《Macromolecular rapid communications》2006,27(17):1495-1500
Summary: Cellulose was dissolved rapidly in 9.5 wt.‐% NaOH and 4.5 wt.‐% thiourea aqueous solution pre‐cooled to −5 °C to prepare a transparent solution. Novel cellulose multi‐filament fibers were spun successfully, for the first time, from the cellulose dope on an extended laboratory scale. The results from 13C NMR, scanning electron microscopy and wide angle X‐ray diffraction (WAXD) patterns indicated that the fibers exhibited cellulose II character and possessed a circular cross‐section and smooth surface. The tensile strength of the novel fibers reached 1.9–2.2 cN · dtex−1. 2D WAXD and SAXS patterns revealed that, with a drawing progress, the orientation factor increased and mechanical properties were improved.
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Nitrogen trichloride undergoes an exceptionally facile reaction with trialkylboranes, apparently by a free radical chain process involving a homolytic substitution at the boron center, providing a new route from organoboranes to the corresponding alkyl chlorides. 相似文献
28.
Shingjiang Jessie Lue Da-Tung Lee Jeng-Yo Chen Chun-Hung Chiu Chien-Chieh Hu Y.C. Jean Juin-Yih Lai 《Journal of membrane science》2008
The diffusion coefficients of water vapor in poly(vinyl alcohol)–fumed silica (PVA–FS) nano-composite membranes were determined using the gravimetric method. Water vapor was observed to diffuse more rapidly in membranes with increased FS content. The vapor diffusion coefficient was determined as 1.2 × 10−13 m2/s in pure PVA and was observed to increase to 3.0 × 10−13 m2/s in PVA composites containing 30% FS nano-particles. The free-volumes of PVA–FS membranes were characterized using positron annihilation lifetime (PAL) spectroscopy. PAL results showed that both the ortho-positronium (o-Ps) lifetime and intensity increased with the addition of FS. The intensity (I3) was found to be higher than the estimated value determined from the linear combination of the data from pristine PVA and FS, and correlated excellently with the polymer amorphous content. The PAL results indicate that a higher FS content in PVA increases the free-volume hole size (a volume increase from 40 to 55 Å3) and free-volume hole density (an I3 increase from 23 to 28%), resulting in a higher fractional free-volume in the nano-composites. The increase in the relative polymer free-volume with higher FS content was associated with a decrease in the PVA crystallinity, as determined from differential scanning calorimetry measurements. It is postulated that the incorporated FS nano-particles interrupt polymeric chain packing and retard crystallization during membrane formation. More crystalline segments were transformed into amorphous regimes in the nano-composites containing more FS. A correlation between water diffusivity and the fractional free-volume was obtained, and the water diffusivity was successfully expressed by the free-volume theory. 相似文献
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L. Bouscasse R. Phan-Tan-Luu E. J. Vincent Et J. Metzger 《International journal of quantum chemistry》1973,7(2):357-364
We describe a method to optimize simultaneously Slater orbital exponents. The procedure is based on Newton's method and requires the derivatives of the energy as a function of the exponents. The calculation of these derivatives is described explicitly. The method has been applied to the hydrogen molecule. 相似文献