全文获取类型
收费全文 | 75篇 |
免费 | 29篇 |
国内免费 | 2篇 |
专业分类
106篇 |
出版年
2024年 | 3篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 18篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有106条查询结果,搜索用时 0 毫秒
61.
A new technique has been developed that combines evanescent-field optical sensing with electrochemical control of surface adsorption processes. This new technique, termed "electrochemical optical waveguide lightmode spectroscopy" (EC-OWLS), proved efficient in monitoring molecular surface adsorption and layer thickness changes of an adsorbed polymer layer examined in situ as a function of potential applied to a waveguide in a pilot study. For optical sensing, a layer of indium tin oxide (ITO) served as both a high-refractive-index waveguide and a conductive electrode. In addition, an electrochemical flow-through fluid cell was provided, which incorporated working, reference, and counter electrodes, and was compatible with the constraints of optical sensing. Poly(L-lysine)-grafted-poly(ethylene glycol) (PLL-g-PEG) served as a model, polycation adsorbate. Adsorption of PLL-g-PEG from aqueous buffer solution increased from 125 to 475 ng/cm(2 )along a sigmoidal path as a function of increasing potential between 0 and 1.5 V versus the Ag reference electrode. Upon buffer rinse, adsorption was partially reversible when a potential of >/=0.93 V was maintained on the ITO waveguide. However, reducing the applied potential back to 0 V before rinsing resulted in irreversible polymer adsorption. PLL-g-PEG modified with biotin demonstrated similar adsorption characteristics, but subsequent streptavidin binding was independent of biotin concentration. Applying positive potentials resulted in increased adsorbed mass, presumably due to polymer chain extension and reorganization in the molecular adlayer. 相似文献
62.
63.
Zhongxue Chen Min Zhou Yuliang Cao Xinping Ai Hanxi Yang Jun Liu 《Liver Transplantation》2012,2(1):95-102
A simple ball‐milling method is used to synthesize a tin oxide‐silicon carbide/few‐layer graphene core‐shell structure in which nanometer‐sized SnO2 particles are uniformly dispersed on a supporting SiC core and encapsulated with few‐layer graphene coatings by in situ mechanical peeling. The SnO2‐SiC/G nanocomposite material delivers a high reversible capacity of 810 mA h g?1 and 83% capacity retention over 150 charge/discharge cycles between 1.5 and 0.01 V at a rate of 0.1 A g?1. A high reversible capacity of 425 mA h g?1 also can be obtained at a rate of 2 A g?1. When discharged (Li extraction) to a higher potential at 3.0 V (vs. Li/Li+), the SnO2‐SiC/G nanocomposite material delivers a reversible capacity of 1451 mA h g?1 (based on the SnO2 mass), which corresponds to 97% of the expected theoretical capacity (1494 mA h g?1, 8.4 equivalent of lithium per SnO2), and exhibits good cyclability. This result suggests that the core‐shell nanostructure can achieve a completely reversible transformation from Li4.4Sn to SnO2 during discharging (i.e., Li extraction by dealloying and a reversible conversion reaction, generating 8.4 electrons). This suggests that simple mechanical milling can be a powerful approach to improve the stability of high‐performance electrode materials involving structural conversion and transformation. 相似文献
64.
Raul A. Wapnir Gerard Devas Cecilia Vaquero Solans 《Biological trace element research》1993,36(3):291-305
l-histidine (His) has been shown to enhance the inhibitory effect of zinc on intestinal copper absorption. This study was aimed
at examining whether this effect of His was also extended to the interactions of other divalent cations: ferrous iron, tin,
and cobalt, using an in vivo perfusion system in rats. Copper absorption and intestinal content of this element significantly
decreased in the presence of 2 mM His and ferrous iron. Iron accumulation was greater when His was present than when omitted. A fivefold excess of tin inhibited
copper absorption only when His was present. Citrate, at the same concentration as His, had no effect on copper absorption,
but hepatic copper levels were increased, as compared to the absence of either His or citrate. Addition of 0.5 or 1.0 mM cobaltous salt plus His resulted in a sharp decrease in copper intestinal absorption, with an increase in intestinal tissue
retention. These results confirm earlier findings with zinc and His, and suggest that a general phenomenon, either accelerating
the removal of copper from the intestinal lumen or increasing, the retention of this element by the intestinal tissue, is
a common feature of the interaction between cations of similar electronic configuration to copper and a high-affinity ligand,
such as His. 相似文献
65.
Methodology for determination of the enantiomeric purity of sixteen 2,3-epoxy-1-propanols (glycidols) is delineated. Conversion of these epoxy alcohols and 1-naphthyl isocyanate (NIC) into the 1-naphthyl carbamates is catalyzed by dibutyltin diacetate. Enantiomers of these carbamates are resolved on a Chiralcel® OD column. Advantages of this method include mildness of reaction conditions, nonreliance on diastereomeric derivatization, and appendage of a UV-absorbing chromophore to the analyte. 相似文献
66.
Bomi Hwang Jae-Sam Hwang Juneyoung Lee 《Biochemical and biophysical research communications》2010,400(3):352-357
Psacotheasin is a 34-mer knottin-type peptide that is derived from Psacothea hilaris larvae. In this study, the antifungal activity and mechanism(s) by which psacotheasin affects human fungal pathogens were investigated. Psacotheasin shows remarkable antifungal properties without hemolytic activity against human erythrocytes. To understand the antifungal mechanism(s) of psacotheasin in Candida albicans, flow cytometric analysis with DiBAC4(3) and PI was conducted. The results showed that psacotheasin depolarized and perturbed the plasma membrane of the C. albicans. Three-dimensional (3D)-flow cytometric contour-plot analysis, accompanied by decreased forward scatter (FS), which indicates cell size, confirmed that psacotheasin exerted antifungal effects via membrane permeabilization. The membrane studies, using a single GUV and FITC-dextran (FD) loaded liposomes, indicate that psacotheasin acts as a pore-forming peptide in the model membrane of C. albicans and the radius of pores were presumed to be anywhere from 2.3 to 3.3 nm. Therefore, the current study suggests that the mechanism(s) of psacotheasin’s antifungal properties function within the membrane. 相似文献
67.
Takatoshi Hasemi Takashi Kikukawa Yumi Watanabe Tomoyasu Aizawa Seiji Miyauchi Naoki Kamo Makoto Demura 《BBA》2019,1860(2):136-146
Mastigocladopsis repens halorhodopsin (MrHR) is a Cl?-pumping rhodopsin that belongs to a distinct cluster far from other Cl? pumps. We investigated its pumping function by analyzing its photocycle and the effect of amino acid replacements. MrHR can bind I? similar to Cl? but cannot transport it. I?-bound MrHR undergoes a photocycle but lacks the intermediates after L, suggesting that, in the Cl?-pumping photocycle, Cl? moves to the cytoplasmic (CP) channel during L decay. A photocycle similar to that of the I?-bound form was also observed for a mutant of the Asp200 residue, which is superconserved and assumed to be deprotonated in most microbial rhodopsins. This residue is probably close to the Cl?-binding site and the protonated Schiff base, in which a chromophore retinal binds to a specific Lys residue. However, the D200N mutation affected neither the Cl?-binding affinity nor the absorption spectrum, but completely eliminated the Cl?-pumping function. Thus, the Asp200 residue probably protonates in the dark state but deprotonates during the photocycle. Indeed, a H+ release was detected for photolyzed MrHR by using an indium?tin oxide electrode, which acts as a good time-resolved pH sensor. This H+ release disappeared in the I?-bound form of the wild-type and Cl?-bound form of the D200N mutant. Thus, Asp200 residue probably deprotonates during L decay and then drives the Cl? movement to the CP channel. 相似文献
68.
Jifa Wu Feng Tang Shaoguang Wu Yumeng Li Liangang Xiao Xuhui Zhu Xiaobin Peng 《Liver Transplantation》2024,14(2):2302932
A small molecular phenanthroline derivative Phen-NaDPO (3-[6-(diphenylphosphinyl)-2-naphthalenyl]-1,10-Phenanthroline) to modify tin oxide (SnO2) electron-transport layer (ETL) in organic solar cells is employed. Quantum chemistry calculations and experimental results show that Phen-NaDPO can interact with SnO2, thereby effectively passivating the surface defects, reducing the work function and improving the electrical conductivity of SnO2, leading to more efficient electron extraction and transport in the organic solar cells (OSCs). Moreover, upon the Phen-NaDPO modification, the decreased surface energy of SnO2 ETL accounts for enhanced exciton dissociation and charge transport, due to the more ordered molecular organizations of the active layers. Consequently, the inverted OSCs involving Phen-NaDPO/SnO2 ETLs exhibit an enhanced power conversion efficiency of 17.06% (PM6:Y6) and 18.31% (PM6:L8-BO), which is the highest efficiency for SnO2 ETL-based binary solar cells to date. Furthermore, the devices based on Phen-NaDPO/SnO2 ETL show better device stability (storage stability, photostability and humid stability), with T80 exceeding 200 h encapsulated under light irradiation and 400 h without encapsulation in high-humidity ambient condition. These results demonstrate that the modification of SnO2 using wide-band highly stable conjugated small molecules is very promising for simultaneously improve the efficiencies and device stability of OSCs. 相似文献
69.
Laccase is a promising biocatalyst with many possible applications, including bioremediation, chemical synthesis, biobleaching of paper pulp, biosensing, textile finishing and wine stabilization. The immobilization of enzymes offers several improvements for enzyme applications because the storage and operational stabilities are frequently enhanced. Moreover, the reusability of immobilized enzymes represents a great advantage compared with free enzymes. In this work, we discuss the different methodologies of enzyme immobilization that have been reported for laccases, such as adsorption, entrapment, encapsulation, covalent binding and self-immobilization. The applications of laccase immobilized by the aforementioned methodologies are presented, paying special attention to recent approaches regarding environmental applications and electrobiochemistry. 相似文献
70.
High‐Performance Ta2O5/Al‐Doped Ag Electrode for Resonant Light Harvesting in Efficient Organic Solar Cells 下载免费PDF全文
A efficient indium tin oxide (ITO)‐free transparent electrode based on an improved Ag film is designed by introducing small amount of Al during co‐deposition, producing ultrathin and smooth Ag film with low loss. A transparent electrode as thin as 4 nm is achieved by depositing the film on top of Ta2O5 layer, and organic solar cells based on such ultrathin electrode are built, producing power conversion efficiency over 7%. The device efficiency can be optimized by simply tuning Ta2O5 layer thickness external to the organic photovoltaic (OPV) structure to create an optical cavity resonance inside the photoactive layer. Therefore Ta2O5/Al‐doped Ag films function as a high‐performance electrode with high transparency, low resistance, improved photon management capability and mechanical flexibility. 相似文献