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排序方式: 共有273条查询结果,搜索用时 15 毫秒
1.
2.
由于器件的快速退化,101.5小时似乎成了Znse基蓝绿色半导体激光器难于逾越的寿命极限。分析退化机制,发现在强电流注入的半导体激光器中,热退化具有重要影响。研究表明,用作载流子限制层的宽带Ⅱ-Ⅵ族四元合金(如ZnMgSSe)只能对ZnSe中的电子有效地限制,无法对空穴很好地限制;而对BeTe,却只能对空穴进行有效的限制,无法对电子很好地限制。这导致ZnSe(或BeTe)活性层空穴(或电子)漏电发热,引起退化。本文提出以ZnSe/BeTe超晶格为蓝绿发光层,并用包络函数理论具体计算了阱宽、垒宽对载流子能级的不同影响,考察了ZnSe、BeTe厚度比和超晶格周期对带隙、载流子限制能力的调节。为研制新型长寿命蓝绿色半导体激光器提供了一条新的途径。 相似文献
3.
A fundamental research of structural defects induced upon post-growth processing of ZnSe/GaAs epilayers grown on (100) GaAs
was done by identifying defect-related reflections in the transmission electron diffraction (TED) patterns of ZnSe. Structural
artifacts, other than the as-grown defects, on this material system could be excluded according to our results. Four types
of abnormal reflections have been observed in addition to primary reflections. These extra reflections are sensitive to the
post-growth processing of ZnSe epilayers and may arise from various external effects, rather than epitaxy growth, such as
irradiation damage, surface oxidation, and surface contamination. By mapping these reflections at several major zone axes
using TED patterns, we found that the reciprocal lattice for a ZnSe crystal with structural defects consists of two distinct
types of extra reflections associated with irradiation damage. The first type of extra reflections is ±1/3{111} and the other
is ±1/2{111} corresponding to pure-edge and non-edge dislocation loops, respectively. For (100) oriented wafers, the ±1/3{111}
and ±1/2{111} reflections were observed only on two of the four possible 〈111〉 variants (i.e. [111]Zn and [111]Zn)and this phenomenon was attributed to the anisotropy of defect distribution. Extra reflections associated with surface oxidation
and contamination are also observed. The orientation relationships between a surface hexagonal ZnO and a cubic ZnSe film are
[0001]ZnO//[−111]ZnSe, and [01−11]ZnO//[011]ZnSe. The origin, characterization, and elimination of these induced reflections are discussed. With the knowledge about these
extra effects on structural defect formation, we have shown the real microstructure of ZnSe epilayers. 相似文献
4.
The employment of the Zn(Se,Te) pseudo-graded contacting scheme to p-type ZnSe-based alloys contributes directly to the recent
demonstration of room temperature continuous-wave operation of II– VI green-blue laser diodes. Contact ohmicity is maintained
down to cryogenic temperatures which enabled the investigation of electrical transport properties associated with the p-type
nitrogen-doped ZnSe, Zn(S,Se), and (Zn,Mg)(S,Se). The observation of both persistent photoconductivity and a metastable population
of holes which are in thermodynamic equilibrium with hydrogenic acceptors having reduced activation energy suggests the presence
of a DX-like behavior for holes in p-type (Zn,Mg)(S,Se). 相似文献
5.
合成了两种咪唑啉型双子表面活性剂二(2-十一(十七)烷基-1-甲酰胺乙基咪唑啉)己二胺季铵盐(SUAEIHDI、SHAEIHDI),并进行了红外表征;然后以Zn(Ac)2-2H20为锌源,硒粉为硒源,水合肼为还原剂,SUAEIHDI为表面修饰剂,采用水热法于150℃反应24h,制得球形ZnSe纳米材料,用TEM、SEM、IR、UV-vis和XRD等手段对ZnSe纳米材料进行了表征,并对球形ZnSe的形成机理进行了初步探讨。结果表明:该咪唑啉型双子表面活性剂对于纳米材料具有良好的形貌控制作用和表面修饰作用。 相似文献
6.
Zhaoxia CaiAuthor VitaeGuoxiang ChenAuthor Vitae Xi HuangAuthor VitaeMeihu MaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(2):368-373
A new method for the determination of lysozyme with high sensitivity based on Resonance Rayleigh scattering (RRS) by using Cd doped ZnSe quantum dots (QDs) as a probe was proposed in this experiment. Cd doped ZnSe QDs capped with glutathione were prepared in the water phase. Further, the RRS spectrum, transmission electron microscope, and absorption spectrum of the QDs-lysozyme system have been characterized. In addition, the effects of several factors on scattering intensities were investigated, including pH value of solution, amount of QDs, mixing sequence of each reagent and the coexisting substances. Moreover, the possible mechanism for the RRS enhancement of Cd doped ZnSe QDs-lysozyme system was preliminary discussed. The RRS method for the determination of lysozyme has good sensitivity with the detection limits 6.5 × 10−10 g mL−1. The contents of lysozyme were determined with recoveries of 97.1-101.6% and relativity standard deviation of 2.5-3.1%, respectively. It proved that the method established in our study is very sensitive, rapid, convenient and tolerant for the determination of lysozyme in synthetically and chicken egg white. 相似文献
7.
Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporation rates of both Zn and Se at substrate temperature of 400 °C. The films are doped with Cu by immersion in the Cu(NO3)2-H2O solution for different periods of time. The XRD has not shown a drastic change in the film structure while the electrical resistivity of the deposited film dropped from 109 Ω-cm to about 1.6 Ω-cm for solution immersed films after heat treatment. Optical properties of deposited and doped films, such as film thickness, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range of 300-2200 nm.The optical results show a decrease of the transmission and an increase of the refractive index and a slight shift in the optical band gap. Chemical composition of the Cu is determined by using absorption of immersed films. The composition of Cu is also compared with the composition detected by electron microprobe analyzer (EMPA). 相似文献
8.
The effect of applied electric field on the electronic properties of spherical ZnSe/ZnS core/shell nanocrystals of experimentally relevant size is investigated by the atomistic tight-binding theory. Using this model, the calculations show that a range of electronic properties, including the single-particle spectra, atomistic characters, charge densities, excitonic energies, ground-state coulomb energies, overlaps of the electron and hole wave functions and oscillation strengths, all depend on the strengths of the applied electric field. The spatial distributions of the electron and hole wave functions are induced by the applied electric field. The analysis demonstrates a clear manipulation of the electronic properties of ZnSe/ZnS core/shell nanocrystals by introducing and varying the applied electric field strengths. According to the comprehensive investigations, I suppose that these atomistic computations will be of prospective help for experimental works concentrated on the new optoelectronic devices based on the applied electric field. 相似文献
9.
《International Journal of Hydrogen Energy》2021,46(60):30818-30827
In this paper, dopamine hydrochloride (DPH) is introduced to synthesize ZIF-8@ZIF-67@DPH in the preparation of ZIF-8@ZIF-67. ZnSe/CoSe/NCDPH (N-doped carbon) composites are calcined in a high-temperature inert atmosphere with ZIF-8@ZIF-67@DPH as the precursor, selenium powder as the selenium source. ZnSe/CoSe/NCDPH has high discharge specific capacity, good cycle stability and outstanding rate performance. The first discharge capacity of ZnSe/CoSe/NCDPH is 1616.6 mAh g−1 at the current density of 0.1 A g−1, and the reversible capacity remains at 1214.2 mAh g−1 after 100 cycles, the reversible capacity is 416.7 mAh g−1 after 1000 cycles at 1 A g−1. Therefore, ZnSe/CoSe/NCDPH composites provide a new step for the research and synthesis of new stable, high-capacity, and safe high-performance lithium ion batteries. The bimetallic selenide composites not only have bimetallic active sites, but also can form synergistic effect between different metal phases, which can effectively reduce the capacity attenuation caused by volume expansion and reactive stress enrichment during lithium storage of metal oxide anode materials. Meanwhile, N-doped carbon can improve the conductivity and provide more active sites to store lithium, thus improving its lithium storage capacity. 相似文献
10.
《Ceramics International》2019,45(11):14084-14089
Undoped and Cu-doped ZnSe nanoparticle (NPs) were prepared and grown hydrothermally in aqueous media assisted by microwave irradiation (MWIR) at different synthesis conditions of pH and MWIR times. In the mentioned process, sodium hydroxide (NaBH4), used for preparing selenium ions source with dissolving it and selenium powder in deionized water. To investigate the structural aspects and nanoparticles morphology, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used. According to the results of XRD, no displacement was seen in the position of XRD peaks of ZnSe nanoparticles by altering the pH and microwave irradiation time. XRD analysis demonstrated cubic zinc blende NPs and TEM images indicated round shape morphology of them. Depending to the microwave irradiation time, upon the XRD outputs, the size of the synthesized NPs were in the range of 1.54–2.18 nm. In this research, for samples synthesized at different pHs (= 8, 10.2, 11.2 and 12.2), at two microwave irradiation time of 0 and 6 min, and also at the presence of Cu-dopant (with the contents of 0, 0.1,0.75 and 1.5%), structural characteristics such as dislocation density(δ), lattice strain(ε), size of nanoparticles (D) and full width at half maximum (FWHM:βhkl) have been evaluated upon the Scherrer and Williamson-Hall methods, in which undoped and ZnSe:Cu 0.1% synthesized at pH = 11.2 have the best crystalline quality; such results for the optimum samples, introduce them as promising materials in optoelectronic devices. The results of structural features obtained from Scherrer and Williamson-Hall approaches are highly intercorrelated and show the same trends with the variation of synthesis conditions. 相似文献