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331.
Mi-Hwa Park Soo-Jin Heo Pyo-Jam Park Sang-Ho Moon Si-Heung Sung Byong-Tae Jeon Seung-Hong Lee 《Applied biochemistry and biotechnology》2014,174(2):632-643
Hyperglycemia-induced oxidative stress accelerates endothelial cell dysfunctions, which cause various complications of diabetes. The protective effects of 6,6′-bieckol (BEK), one of phlorotannin compound purified from Ecklonia cava against high-glucose-induced oxidative stress was investigated using human umbilical vein endothelial cells (HUVECs), which is susceptible to oxidative stress. High glucose (30 mM) treatment induced HUVECs’ cell death, but BEK, at concentration 10 or 50 μg/ml, significantly inhibited the high-glucose-induced cytotoxicity. Furthermore, treatment with BEK dose-dependently decreased thiobarbituric acid reactive substances (TBARS), intracellular reactive oxygen species (ROS) generation, and nitric oxide level increased by high glucose. In addition, high glucose levels induced the overexpressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor-kappa B (NF-κB) proteins in HUVECs, but BEK treatment reduced the overexpressions of these proteins. These findings indicate that BEK is a potential therapeutic agent that will prevent diabetic endothelial dysfunction and related complications. 相似文献
332.
In Sun Hwang So Ra Lee Sooyeul Cho Kab Ryong Chae Hyoung Jun Park Ji Hyun Lee Ok Soon Heo Seung Yi Hong Woo-Seong Kim 《Accreditation and quality assurance》2014,19(1):41-46
South Korea’s Ministry of Food and Drug Safety (MFDS) has been developing programs for the inspection and accreditation of food sanitation inspection institutions. Food sanitation inspection institutions such as MFDS regional offices, the Research Institute of Public Health and Environment and authorized private service providers in South Korea must participate in proficiency testing (PT) programs to comply with the Food Sanitation Act and MFDS Notification No. 2012-112. As the PT provider, the MFDS annually plans various microbiological and chemical PT programs for foods, cosmetics, and pharmaceutical products in accordance with ISO/IEC 17043. The aim of this project was to evaluate the performance of microbiological PT programs to ensure the quality of their routine test results. The test materials used were freeze-dried BioBalls from BTF Pty Ltd. Homogeneity and stability were investigated to assess the adequacy of the selected test materials. This project also contains data from inter-laboratory comparisons organized by MFDS in 2011 and 2012. More than 50 laboratories attended the PT program and submitted their results. Laboratory results were rated with z-scores according to the international standard ISO 13528. The results from 2011 and 2012 revealed that all participating laboratories had similar levels of proficiency. Most of the participants received a rating of “Satisfactory.” Moreover, the percentage of participants who received a rating of “Unsatisfactory” decreased from 3.5 % in 2011 to 2.0 % in 2012. 相似文献
333.
Structural evolution in microbial polyesters 总被引:1,自引:0,他引:1
Heo K Yoon J Jin KS Jin S Sato H Ozaki Y Satkowski MM Noda I Ree M 《The journal of physical chemistry. B》2008,112(15):4571-4582
The crystallization behavior of microbially synthesized poly(3-hydroxybutyrate) (PHB) and its copolymers [P(HB-co-HHx)] containing 2.5, 3.4, and 12 mol % 3-hydroxyhexanoate (HHx) comonomer and the melting of the resultant crystals were studied in detail using time-resolved small-angle X-ray scattering and differential scanning calorimetry. The polyesters were found to undergo primary crystallization as well as secondary crystallization. In the primary crystallization, the thicknesses of the lamellar crystals were sensitive to the crystallization temperature, but no thickening was observed throughout the entire crystallization at a given temperature. The thickness of the lamellar crystals in the PHB homopolymer was always larger than that of the amorphous layers. In the copolymers, by contrast, the randomly distributed HHx comonomer units were found to be excluded from the lamellar crystals into the amorphous regions during the isothermal crystallization process. This interrupted the crystallization of the copolymer chains, resulting in the formation of lamellar crystals with thicknesses smaller than those of the amorphous layers. The lamellar crystals in the copolymers had lower electron densities compared to those formed in the PHB homopolymer. On the other hand, secondary crystallization favorably occurred during the later stage of isothermal crystallization in competition with the continuous primary crystallization, forming secondary crystals in amorphous regions, in particular in the amorphous layers between the primarily formed lamellar crystal stacks. Compared to the primarily formed lamellar crystals, the secondary crystals had short-range-ordered structures of smaller size, a broader size distribution, and a lower electron density. 相似文献
334.
Oh BR Seo JW Heo SY Hong WK Luo LH Kim S Park DH Kim CH 《Applied biochemistry and biotechnology》2012,166(1):127-137
In the present work, mutant strains of Klebsiella pneumoniae with deletions of the als gene encoding acetolactate synthase involved in synthesis of 2,3-butanediol, the ldhA gene encoding lactate dehydrogenase required for lactate synthesis, or both genes, were prepared. Production of 1,3-propanediol
(1,3-PD) from glycerol was enhanced in the ldhA mutant strain (ΔldhA), but lower in Δals or Δals ΔldhA mutant strains compared to the parent strain, concomitant with a reduction in the glycerol consumption rate, indicating that
deletion of ldhA alone was useful to improve 1,3-PD production. Fed-batch fermentation analysis revealed that, in the ΔldhA mutant strain, 1,3-PD production was higher at low pH than at neutral pH; the reverse was true for the parent strain. Further
optimization of culture conditions, by variation of aeration and glycerol feed rates, dramatically improved the production
of 1,3-PD by the mutant strain. The maximum level attained was 102.7 g l−1 of 1,3-PD from glycerol. 相似文献
335.
Heo DU Lee JB Han YD Joo J Lee H Lee H Choi DH 《Langmuir : the ACS journal of surfaces and colloids》2012,28(29):10948-10955
A new functionalized triethoxysilane bearing an X-shaped, anthracene-based semiconducting molecule on one arm was designed and synthesized as a precursor for the preparation of a self-assembled monolayer (SAM) on a SiO(2) substrate. 3-Isocyanatopropyl triethoxysilane was reacted with a monohydroxyl-terminated X-shaped, anthracene-based semiconducting molecule in the presence of tin catalyst. The 6-(5-((6-((5-hexylthiophen-2-yl)ethynyl)-9,10-bis(phenylethynyl)anthracen-2-yl)ethynyl)thiophen-2-yl)hexyl 3-(triethoxysilyl)propylcarbamate (BATHT-TEOS) was found to be stable and sufficiently reactive to form organic monolayers on hydroxylated SiO(2) surfaces. The structures and properties of these SAMs were investigated using X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy, photoluminescence (PL) spectroscopy, laser scanning confocal microscopy-PL spectrometry, and spectroscopic ellipsometry. In this work, BATHT-SAM was employed as an interfacial layer on SiO(2) to fabricate ultrathin film transistors (UTFTs, active layer thickness ~ 16.09 nm). The device UTFT-I, made of 0.06 wt % 5,5'-(9,10-bis(phenylethynyl)anthracene-2,6-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene) (BATHT) solution on an n-octyltrichlorosilane-SAM/SiO(2) layer, showed no gate effect for the carrier transport behavior; however, the device UTFT-II, fabricated on BATHT-SAM/SiO(2), exhibited field effect mobilities of 0.04 cm(2) V(-1) s(-1) (I(on/off) ~ 6.3 × 10(3) to 1.0 × 10(4)). This can be attributed to the effect of BATHT-SAM inducing uniform coverage and ordering of BATHT molecules as an upper layer. 相似文献
336.
Xiang Shen Feifei Chen Xin Lv Shixun Dai Xunsi Wang Wei Zhang Baoan Song Tiefeng Xu Qiuhua Nie Chao Liu Kai Xu Jong Heo 《Journal of Non》2011,357(11-13):2316-2319
Chalcohalide glass-ceramics based on GeS2–Ga2S3–CsCl pseudo-ternary system were prepared by heat treatment method. X-ray diffraction and scanning electron microscope studies confirmed the formations of Ga2S3 and GeS2 phase grains with sizes of 2–5 and 80 nm, respectively. Z-scan technology was employed to investigate the third-order nonlinear optical characteristics of both precursor glass and its glass ceramics at 800 nm. The results show that nonlinear refractive index n2 as well as nonlinear absorption coefficient β increase after heat treatment, which is due to quantum effects, and the largest n2 of the glass ceramics is 4.3 × 10? 11 esu which is 4 times larger than that of the host. 相似文献
337.
We report the factors influencing the capture of DNA by DNA-modified microbeads confined within a microfluidic channel. Quantitative correlation of target capture efficiency to probe surface concentration, solution flow rate, and target concentration are discussed. The results indicate that the microfluidic system exhibits a limit of detection of approximately 10(-10) M (approximately 10(-16) mol) DNA and a selectivity factor of approximately 8 x 10(3). Typical hybridization times are on the order of minutes. 相似文献
338.
Kwon Taek Lim Hullathy Subban Ganapathy Haldorai Yuvaraj Hoon Heo 《Journal of fluorine chemistry》2006,127(6):730-735
γ-Cyclodextrin (γ-CyD) was hydrophobically modified by selective functionalization at the C-6 position (primary face) with fluoroalkyl ester groups. This new amphiphilic γ-CyD was prepared in a facile one-pot synthesis by direct esterification of γ-CyD with perfluorobutanoic acid on the narrow rim of macrocylic molecule. The selective per-substituted product, octakis (6-O-perfluorobutanoyl)-γ-cyclodextrin (γ-CyD-F), was confirmed by 1H NMR, 13C NMR and 19F NMR spectroscopic methods. The complexing ability of the γ-CyD-F was investigated with different types of anionic surfactant having single or double hydrophobic tail groups. Predominant complex formation was observed in all cases with an equimolar mixture of surfactant and γ-CyD-F in methanol irrespective of the type of the surfactant. 相似文献
339.
Phosphor-in-glass (PiG) typed robust color converters were fabricated using Pb-free silicate glasses for high-power white LED applications. SiO2-B2O3-RO(R=Ba,Zn) glass powder showed good sintering behavior and high visible transparency under the sintering condition of 750?°C for 30?min without noticeable interaction with phosphors. By simply changing the thickness of the PiG plate or mixing ratio of glass to Y3Al5O12:Ce3+ phosphor, CIE chromaticity coordinates of the LED can be easily controlled. Enhanced thermal quenching property of PiG compared to phosphor with conventional silicone resin suggests its prominent feasibility for high-power/high-brightness white LEDs. 相似文献
340.
Y.S. KimS.B. Heo H.M. LeeY.J. Lee I.S. KimM.S. Kang D.H. ChoiB.H. Lee M.G. KimDaeil Kim 《Applied Surface Science》2012,258(8):3903-3906
Transparent conductive GZO films were deposited on polycarbonate substrates by electron beam assisted radio frequency (RF) magnetron sputtering and then the influence of electron irradiation on the structural, optical and electrical properties of GZO films was investigated by using X-ray diffractometry, UV-vis spectrophotometry, four point probes, atomic force microscopy and UV photoelectron spectroscopy. Sputtering power was kept constant at 3 W/cm2 during deposition, while electron irradiation energy varied from 450 to 900 eV.Electron irradiated GZO films show larger grain sizes than those of films prepared without electron irradiation, and films irradiated at 900 eV show higher optical transmittance in the visible wavelength region and lower sheet resistance (120 Ω/□) than other films. The work-function is also increased with electron irradiation energy. The highest work-function of 4.4 eV was observed in films that were electron irradiated at 900 eV. 相似文献