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51.
分析了在大接触应力的磨损条件下,表面残余应力和硬度对40Cr电火花强化层耐磨性的影响,探讨了其磨损机理。结果表明:滚动磨损和滚、滑动磨损时,随着试样表层硬度的提高,试样的耐磨性增大;强化层中的残余压应力可以提高强化层的硬度并增强其耐磨性。滚动磨损时,电火花强化层的磨损方式主要为粘着磨损、疲劳磨损和磨粒磨损三种机制;在滚、滑动磨损时,除上述三种机制外,还发生了氧化磨损。 相似文献
52.
53.
ZHOU Hai CHEN Fei YAO Bin ZHANG Jian-jun CHEN Li Beijing Institute of Petro-Chemical Technology Collage of Mechanical Engineering China 《材料热处理学报》2004,(5)
GAS multi-elements penetrating technology is a newsurface hardening technology developed on the basisof carbonitriding technology.It can not only shortenthe production period,but also improve the mechanicalperformances of the parts,such as torsional strength,flexural strength,wear resistance,and fatigue resistance"'.It features low-temperature multi-elementspenetration that the physical chemistry process ofoxidation-reduction generates the active atoms in thepart surface.In the beginning,the … 相似文献
54.
纳米磨料硬度对超光滑表面抛光粗糙度的影响 总被引:5,自引:0,他引:5
通过均相沉淀法制备了纳米CeO2和Al2O3粉体,研究了在相同抛光条件下纳米CeO2、Al2O3和SiO2磨料对硅片的抛光效果,用原子力显微镜观察了抛光表面的微观形貌并测量其表面粗糙度.结果表明:纳米CeO2磨料抛光后表面具有更低的表面粗糙度,在5 靘5 靘范围内表面粗糙度Ra值为0.240 nm,而且表面的微观起伏更趋向于平缓;考虑了纳米磨料在抛光条件下所发生的自身变形,其变形量相当于一部分抵消了纳米磨料嵌入基体材料的切削深度,而这个切削深度最终决定了抛光表面的粗糙度;分析指出这个变形量与纳米磨料的硬度成反比,硬度低的纳米磨料由于自身变形量大,导致切削深度小,抛光后表面的粗糙度值低.解释了在相同的抛光条件下不同硬度的纳米磨料具有不同的抛光表面粗糙度的原因. 相似文献
55.
Jun T. Kim Dong S. Cha Gee D. Lee Tae W. Park Dong K. Kwon Hyun J. Park 《应用聚合物科学杂志》2002,83(2):423-434
Biodegradable plastics were produced from sweet potato pulp (SPP) and cationic starch (CS) or chitosan composite (CC) by compression molding and their mechanical properties were tested. A universal testing machine, Rockwell hardness tester, and Izod impact tester were used for testing the mechanical properties (flexural strength, Rockwell hardness, and Izod strength) of the plastics. A central composite second‐order design was used to study the effects of temperature, time, and moisture content on the flexural strength, Rockwell hardness, and Izod strength of SPP/CS and SPP/CC blended plastics. The flexural strength, Rockwell hardness, and Izod strength of SPP‐based plastics was 101.1–305.9 kg/cm2, R29.0–R96.7, and 0.6–3.0 kg cm cm?2, respectively. Regression analysis predicted the optimal mechanical properties (flexural strength, Rockwell hardness, and Izod strength) to be attained with a 150–160°C temperature, 15–20‐min reaction time, and 20–23% moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 423–434, 2002 相似文献
56.
在混合溶剂中加入甲基丙烯酸、各种甲基丙烯酸酯单体以及引发剂AIBN和链转移剂DDM,在85℃下反应合成了丙烯酸树脂。分别研究了不同酸值和羟值的丙烯酸单体、不同Tg的丙烯酸树脂以及各种助溶剂和中和剂对漆膜性能的影响。获得了丙烯酸阳极电泳涂料的最佳配方:丙烯酸共聚树脂的酸值为65 mg KOH/g、羟值为69 mg KOH/g、Tg为20℃,溶剂是体积比为1∶1的丙二醇单甲醚和异丙醇的混合物,中和剂是二乙醇胺。该电泳涂料具有良好的槽液稳定性和起泡消泡性。制得的涂膜外观平整、丰满、光亮,厚度为18~20μm,硬度为5 H,冲击强度为500 N/cm2,附着力为1级,柔韧性为1 mm,耐烟雾实验超过400 h。 相似文献
57.
Yinzhong Guo Vijay M. Mannari Pulin Patel John L. Massingill 《Journal of Coatings Technology and Research》2006,3(4):327-331
A series of soybean oil phosphate ester polyols (SOPEP) was prepared by reaction of fully epoxidized soybean oil with phosphoric
acid and simultanoeous hydrolysis in the presence of a polar solvent. The polyols were characterized by determination of acid
value, oxirane number, hydroxyl value, molecular weight (GPC), and FTIR spectra. These polyols with varying amounts of acid
phosphate groups could be self-emulsified to form aqueous dispersions after neutralization with organic base. These aqueous
dispersion showed varying degrees of stability and their appearance ranged from opaque dispersions to translucent to clear
solutions. Waterborne coating compositions were prepared using these aqueous dispersions as principal components and their
thermally cured film properties were studied. it was found that by careful selection and formulation, SOPEPs can be successfully
used for low-VOC waterborne coating formulations. SOPEPs with 3.5% phosphate ester content showed visibly superior corrosion
resistance properties. 相似文献
58.
59.
Arun K. Bhattacharya John J. Petrovic 《Journal of the American Ceramic Society》1991,74(10):2700-2703
The indentation technique has been used to evaluate the hardness and fracture toughness of SiC-reinforced MoSi2 composites made by hot-pressing. It is seen that the toughness increases with increasing indentation crack length (under increasing load) and a probable mechanism responsible for this behavior is described. It is also observed that there is an optimum volume fraction of SiC particles for which the maximum fracture toughness of the composite can be achieved. 相似文献
60.
The microhardness, H, of PMMA/natural rubber blends, prepared following the solution method has been investigated by means of the microindentation technique. Hardness changes are correlated with the variation of the glass transition temperature. The influence of temperature and degree of deformation on H were additionally examined. The inclusion of rubber particles in the PMMA matrix is shown to soften the blends. The variation of the micromechanical property at the phase boundary of polymer/rubber particle has been studied. Results reveal that H drastically drops at the interphase. In the case of the drawn materials, the indentation anisotropy (ΔH) is shown to gradually increase with the draw ratio, where ΔH is found to be higher for the PMMA/rubber blend than for the original PMMA. This result is explained by the higher orientation of the PMMA molecules near the periphery of stretched rubber particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 205–210, 2004 相似文献