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941.
本文以BaCO3、MgO、Ta2O5为原料,采用固相反应法合成了Ba(Mg1/3Ta2/3)O3(简称BMT)陶瓷粉末,利用大气等离子喷涂技术制备了BMT/YSZ双层陶瓷涂层。利用XRD、SEM和金相显微镜检测了BMT粉体及涂层的物相组成和显微结构。采用水淬法考核了涂层的抗热震性能。结果表明:1450℃下煅烧4h可合成出具有复合钙钛矿结构的BMT粉末,粉末具有良好的高温相结构稳定性。等离子喷涂制备的BMT/YSZ涂层组织致密,涂层系统中各界面结合紧密。涂层在室温至1150℃间热震9次后发生片状剥落,剥落位置位于BMT层间,BMT材料低的断裂韧性和第二相Ba3Ta5O15的存在是导致涂层失效的主要原因。 相似文献
942.
G. A. Blann 《Journal of Thermal Spray Technology》1994,3(3):263-269
Accurate microstructural analysis of thermally sprayed coatings is possible only if specimen preparation produces a surface
that clearly reveals the true microstructure. Comparison of similar specimens pre-pared by different laboratories, or different
personnel in the same laboratory, often shows significant dif-ferences or variations in the microstructures, producing conflicting
information that lowers the confi-dence level of microstructural analysis. A study was conducted on an alumina coating and
an 8 wt% yttria-stabilized zirconia coating, both sprayed on metal substrates, to evaluate the effects of two differ-ent encapsulating
procedures. 相似文献
943.
944.
The heat treatment effect on the characteristics and tensile strength of plasma-sprayed alumina, yttria-stabilized zirconia
(YSZ), and mixtures of alumina and YSZ coatings on titanium was investigated. The as-sprayed structures of alumina and YSZ
coatings consists of a and y alumina phases, and cubic and tetragonal zirconia phases, respectively. The tensile strength
of the coatings containing a large amount of YSZ is increased from 25 to 50 MPa by heat treatment at 800 °C. The 60% YSZ-AI2O3 coating showed the highest tensile strength. The tensile strength increase of the YSZ-containing coating by heat treatment
is caused by formation of 10 to 100 nm wide microcracks. The interface adhesion strength between the heat-treated titanium
substrate and the alumina-containing coating is increased by chemical reaction at the in-terface. Thus, a heat-treated alumina
and zirconia mixture coating may be favorable in obtaining high tensile strength due to microcrack formation in the coating
and the chemical reaction at the interface.
During this work, S. Baba was a graduate student at Kyushu Institute of Technology, Sumitomo Metal Ind. Ltd., Osaka, Japan. 相似文献
945.
紫外光对涂层的老化作用 总被引:19,自引:0,他引:19
用人工加速的方法研究了紫外光对涂层的影响.用石英晶体微天平(QCM)测试发现老化后涂层对H2O和SO2的吸附率明显增大.电化学阻抗(EIS)测定发现孔隙率随光照射时间增加而增大,涂层电阻随光照时间增加而减小.傅利叶变换红外光谱(FTIR)分析表明,光照使涂层分子碳链断裂,醇酸涂层发生在芳香酯的C—O键,聚氨酯涂层发生在芳香酯的C—O键和氨酯键C—N,同时有一些亲水基团生成.用扫描电子显微镜(SEM)观察涂层表面产生了许多孔穴.涂层吸水率增加是由亲水基团增加和孔隙增加共同引起的,但孔隙增加的贡献更大.而涂层对SO2吸附率的增加是由双键α—H过氧化物的增加和孔隙的增加共同引起的,α—H过氧化物的增加的贡献更大。 相似文献
946.
Schottky diodes of rare-earth, praseodymium (Pr)-doped and samarium (Sm)-doped furazano [3,4-b] piperazine (FP), sandwiched between Al and indium-tin oxide (ITO) were made by a spin-coating technique. The diodes, in which doped FP behaves as a p-type organic semiconductor, exhibit rectification behaviour. The p-type semiconductivity and rectification properties of the devices improve with rare-earth doping. The electrical effects observed in these devices are explained in terms of the p-type semiconducting behaviour of the doped FP thin films and the formation of a blocking contact (Schottky barrier) with the Al electrode and ohmic contact with the ITO electrode. Various electrical parameters such as carrier mobility, position of Fermi level, free carrier concentration, trap density, trap level and conductivity of doped FP are calculated and discussed. It is found that the position of the Fermi level shifts toward the valence band on rare-earth doping; concentration of free carriers and carrier mobility increase on doping. From the capacitance-voltage (C-V measurements, various electrical parameters such as barrier height, density of ionized acceptor atoms and depletion layer width are calculated and discussed. From the action spectra and absorption spectra it is confirmed that the Al-doped FP interface forms a Schottky barrier and the ITO-doped FP interface shows ohmic contact. The photovoltaic measurement on the two devices reveals that the short circuit current, open circuit voltage, fill factor and power conversion efficiency increase on rare-earth doping. 相似文献
947.
D. M. Nissley 《Journal of Thermal Spray Technology》1997,6(1):91-98
Analytical models for predicting ceramic thermal barrier coating (TBC) spalling life in aircraft gas tur-bine engines are
presented. Electron beam/physical vapor-deposited and plasma-sprayed TBC systems are discussed. An overview of the following
TBC spalling mechanisms is presented: (1) metal oxidation at the ceramic/metal interface, (2) ceramic/metal interface stresses
caused by radius of curvature and inter-face roughness, (3) material properties and mechanical behavior, (4) component design
features, (5) tem-perature gradients, (6) ceramic/metal interface stress singularities at edges and corners, and (7) object
impact damage. Analytical models for TBC spalling life are proposed based on observations of TBC spall-ing and plausible failure
theories. Spalling was assumed to occur when the imposed stresses exceed the material strength (at or near the ceramic/metal
interface). Knowledge gaps caused by lack of experimen-tal evidence and analytical understanding of TBC failure are noted.
The analytical models are considered initial engineering approaches that capture observed TBC spalling failure trends. 相似文献
948.
电化学阻抗谱方法研究评价有机涂层 总被引:98,自引:7,他引:98
介绍了研究涂层性能的电化学阻抗谱(EIS)实验方法以及该方法的在研究,评价有机涂层方面的应用。由于涂层的种类很多,每种涂层的防护机制各不相同,其EIS的数学物理模型也各不相同,本文共建立了6种模型(等效电路)来分别处理不同有涂层体系的电化学阻抗谱,介绍了EIS数据处理的快速方法-特殊频率法。 相似文献
949.
钛合金表面激光熔覆原位生成TiC增强复合涂层 总被引:31,自引:2,他引:31
利用Cr3C2和TiC生成自由能和稳定性的差异,通过激光熔化法在Ti6Al4V表面制备TiC颗粒增强钛基复合材料涂层,结果表明:选择合适的激光处理工艺,可使Cr3C2和Ti合金粉末通过原位结晶置换反应生成TiC/Ti复合材料熔覆层。亚微米级的TiC颗粒均匀地分布于复合材料的基体中,复合材料的基体组织随合金粉末的成分不同而改变。 相似文献
950.
A vacuum impregnation procedure for examining the microstructure of thermal spray coatings has been evaluated using a low-viscosity
fluorescent resin. The use of confocal laser scanning microscopy for examining the microstructure allows three-dimensional
image reconstruction of the sample. Relationships between defects (i.e., porosity or micro/macrocracking) and coating properties
can be established more accurately with the proposed methodology because it enables quantitative analysis. 相似文献