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131.
弱配筋砼构件的裂缝宽度计算是一个急待解决的理论和工程应用问题,目前研究的资料很少。本文通过50多根受弯、大偏心受压弱配盘砼构件的试验研究及概率分析,提出了这种构件裂缝宽度及间距概率分布属性,提出特征裂缝宽度计算公式,并用模糊失效慨率进行了可靠度分析。找出现有计算公式存在的缺点和问题。建议公式与试验结果拟合性较好,可供规范修订和工程设计参考。 相似文献
132.
He Jishan Department of Geology Central Sough University of Technology Changsha China 《中国有色金属学会会刊》1993,(4)
The dual-frequency(DF)IP is a new kind of frequency domain IP method.Not only is thedual-frequency current transmitted simultaneously but the electric potential difference due to dualfrequency current is measured synchronously.This paper discusses the principle and charateristicof DF current, DF current can be formed by two rectangular currents which must be coherent orelse false Percent Frequency Effect(PEE)will occur.DF currents with different waveforms areequivalent in the ability of detecting IP anomalies.Unstable current has much less effect of DFIP than on conventional variable frequency method;in fact,there is no need to stabilize currentin DF IP method.There are many differences between harmonic contents of DF current and thatof rectangular wave used in variable frequency method,but theoretical analysis,labaratory mod-eling and field data all show that the anomalies of both DF and variable frequency method are sim-liar in character and close in value.DF IP can match variable frequeney IP and time domain IPin the ability of detecting IP anomaly,furthermore,dual-frequency IP measurements are morerapid,more accurate and more simple in operation. 相似文献
133.
NiAl基金属间化合物研究现状与前景 总被引:2,自引:0,他引:2
介绍了NiAl基金间化合物研究的现状与前景。NiAl由于具有高熔点、低密度和良好的抗氧化性等性能而被认为是下一代的高温结构材料,然而NiAl在室温时塑性低和高温时强度低限制了它作为工程材料的应用。对NiAl的晶体结构和缺陷、力学性能进行研究,采用合金化、控制显微结构和改进加工技术等方法使NiAl的室温塑性和高温强度都得到了提高。 相似文献
134.
135.
颗粒增强金属基复合材料(MMCs)具有良好的综合性能,在航空、汽车及民用工业中的应用前景十分广阔。近年来粉末雾化喷射成形工艺用于制备颗粒增强MMCs受到了重视与发展。该方法通过快速凝固获得组织均匀、细小、无宏观偏折和高性能的新材料。在沉积过程中向基体合金的喷雾中喷入增强相颗粒即可制成高性能MMCs。本文介绍这一方法的基本原理和最新进展。 相似文献
136.
球罐角变形的应力场和容限研究 总被引:1,自引:0,他引:1
本文用渐近展开式求解一阶非线性微分方程,导出了以球壳为力学模型的角变形应力场。定量解决了角变形区域(2a)和弯曲程度(m)对应力集中系数的影响。对解析解进行多元回归得出满足工程精度要求的应力场算式。用有限元验证了解析解。针对现行规范(JB1127—82)的一些不足,推荐了角变形的容限。 相似文献
137.
Cheng FangAuthor Vitae Jishan HeAuthor VitaeZhencheng ChenAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):545-550
A disposable amperometric biosensor for detecting the total cholesterol was fabricated which comprises a sensing electrode and a reference electrode in simultaneous contact with an integrated reagent layer. The integrated reagent layer formed by coating a working ink containing cholesterol esterase, cholesterol dehydrogenase, coenzyme, redox mediator, surfactant, stabilizer, filler and at least one aqueous thickening agent. The biosensor showed the linearity for 50-500 mg/dL cholesterol acetate. The minimum detection limit of the cholesterol was 50 mg/dL. The effects of temperature and the stability of immobilized enzymes were also studied. A good correlation was found among cholesterol values obtained by commercial colorimetric test strip and clinical/laboratory methods. The biosensor showed an acceptable reproducibility, good stability and low interferences. 相似文献
138.
在对近区场积分表达式中各积分因子特性分析的基础上,提出了一种解决近区场含两个Bessel函数奇异积分的分段Simpson积分法,较好地处理了近区视电阻率的数值计算问题。 相似文献
139.
Chemodynamic therapy (CDT) is an effective tumor treatment strategy in which FeII reacts with hydrogen peroxide (H2O2) in tumor cells to produce highly toxic hydroxyl radical (.OH) through the Fenton reaction. However, the content of endogenous H2O2 in cells is limited, and the reaction between FeIII and H2O2 is inefficient, greatly limiting the efficiency of the Fenton reaction and reducing the effectiveness of tumor treatment. Therefore, in this work, we designed and synthesized a new type of nano-system (CaO2@TA-FeIII) for the enhanced CDT of tumors, in which the polyphenolic compound- tannic acid (TA) and FeIII formed a TA-Fe nano-coating on the surface of calcium peroxide (CaO2) nanospherical aggregates. When the CaO2@TA-FeIII nanoconjugates reach the tumor site, the CaO2 contained in the nanoconjugates produces H2O2 after disintegration in tumor cells, and the carried TA rapidly reduces FeIII to FeII, solving the two major shortcomings in CDT of (1) insufficient content of H2O2 in cancer cells, and (2) low catalytic efficiency of the Fenton reaction. Additionally, the .OH produced in the Fenton reaction induces oxidative stress for the tumor cells, promoting the occurrence of the “calcium overload” process, and thereby accelerating the death of tumor cells. Experimental results in vitro and in vivo showed that CaO2@TA-FeIII nanoconjugates can effectively kill cancer cells and display an excellent tumor therapeutic effect. We believe that the CaO2@TA-FeIII nanoconjugates are a promising new nano-platform for highly effective tumor treatment. 相似文献
140.
A disposable electrochemical immunofiltration test strip for the rapid detection of α-fetoprotein (AFP) was developed. The test strip was constructed by assembly of screen-printed carbon electrodes, absorption-water pad, nitrocellulose membrane modified by anti-AFP antibody and glass fiber membrane conjugated with ferrocene monocarboxylic acid (FC) labeling AFP. The analytical system utilizes flow-through immunofiltration and competitive immunoassay techniques in combination with an amperometric sensor. The parameters affecting the immunoassay such as selection of filter membrane, membrane pore-size, and antibody binding capacity were investigated and optimized. The immunofiltration system allows us to specifically and directly detect AFP in serum with a low detection limit of 6 ng/mL. The working range is from 6 to 500 ng/mL with an overall analysis time of 5 min for one sample. This electrochemical immunoassay system enabled us to construct a novel point-of-care testing device for the monitoring of biomarker including AFP. 相似文献