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Disinfection by-product (DBP) formation was evaluated before and after ozone implementation at two full-scale drinking water facilities in Las Vegas, NV USA. The two treatment plants used preozonation for primary disinfection followed by direct filtration with subsequent chlorination for secondary disinfection. DBP data was evaluated from the finished water of the two treatment plants along with six locations in the distribution system. Results showed that preozonation reduced the formation of total trihalomethanes (TTHM) by up to 10 μg/L and the sum of five haloacetic acids (HAA5) by up to 5 g/L. These reductions were primarily due to decreases in the di- and trichlorinated DBPs such as chloroform, bromodichloromethane, and trichloroacetic acid. Ozonation appeared to shift the speciation of TTHMs and HAA5 to favor increased formation of the di- and tribrominated species such as bromoform, chlorodibromomethane, and dibromoacteic acid. A bromide mass balance showed that <30% of the raw water bromide was accounted for by the formation of TTHMs (8–21%), HAAs (2–3%) and bromate (5%). Reducing the concentration of THMs and HAAs is often not the primary purpose of ozonation, but it can assist utilities in meeting regulatory requirements during drinking water treatment. 相似文献
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国外进口的钢材在进行焊接时,由于工艺的不成熟极易造成钢材组织粗大,成分偏析和焊接变形,从而导致其理化性能达不到设计者要求。本文将对此问题作个浅显的探讨。 相似文献
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A. Das 《金属精饰学会汇刊》2017,95(5):276-281
Hydroxyapatite (HA) is popularly used as a biocompatible coating material for metallic implants, in view of its improved bone fixation property, leading to an increased life of the implant. However, the deposition of HA on medical grade UNS S31254 stainless steel (SS254) for orthopaedic implant applications by the radio-frequency magnetron sputtering technique is unreported in the literature so far. The surface morphology of the deposited HA coatings was characterised using scanning electron microscopy and atomic force microscopy, while their phase composition was determined using X-ray diffraction. The thickness and adhesive strength of the HA coatings were determined using an ellipsometer and a tensometer, respectively. Finally, the antibacterial efficacy and bioactivity of the deposited coatings were confirmed using fluorescence activated cell sorting and immersion testing in simulated body fluid environment. The results obtained showed that the HA coatings grown on SS254 using magnetron sputtering possess desirable surface properties as well as good adhesion and biocompatibility properties, ideally suited for potential applications in orthopaedic implants. 相似文献
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对波纹管原型试件加速应力腐蚀试验方法进行了研究,并设计制作了高温腐蚀环境下适合波纹管原型试件加速应力腐蚀试验装置;针对316L 、254SMo、Incoloy 800三种材料波纹管分别进行了抗氯离子加速应力腐蚀试验,研究三种材料的抗应力腐蚀性能及特征.结果表明:在42%沸腾氯化镁环境下,254SMo材料波纹管应力腐蚀寿命是常用材料316L 波纹管约30倍, Incoloy 800材料波纹管应力腐蚀寿命是常用材料316L 波纹管的20多倍,选用254SMo或Incoloy 800作为波纹管的新材料将显著提高波纹管的抗应力腐蚀寿命;受应力状态的影响,进行应力腐蚀波纹管将在波峰波侧形成子午向裂纹或在波峰处形成周向裂纹,此两种裂纹扩展特征也不同. 相似文献
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根据有源RFID系统的卓越性能以及超低功耗的芯片特性,结合矿井无线传输的特点,设计了煤矿井下人员定位系统.系统的读写器和标签均采用TI公司的低功耗MSP430F254单片机作为主控芯片,采用CC2500芯片作为射频芯片.采用ASP.NET+SQL Sever2000,构建了基于Web的煤矿井下人员定位系统的软件系统.矿井人员定位系统能对煤矿入井人员进行实时跟踪监测和定位、查询事故现场的人员位置分布情况、被困人员数量等信息,为事故抢险提供科学依据。 相似文献
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超声空化作用于水中天然有机质特性研究 总被引:1,自引:0,他引:1
利用超声空化作用去除水中天然有机质(Natural Organic Matter,简称NOM)不会产生消毒副产物.研究了采用低频高功耗率的超声处理富里酸溶液,结果表明:由于超声空化的热解及氧化作用,随着声功率及富里酸溶液浓度的增加,溶液的pH、ORP逐渐减小,溶液的温度、浊度逐渐增加,体系中加入盐酸后能够放大超声作用.作为水中NOM浓度的替代参数,UV<,254>在超声作用下缓慢增加,而总有机碳(TOC)的超声降解符合准一级反应规律,在20min超声作用之后,TOC去除率由21.2%增至31.6%,加入盐酸后,由24.7%增至34.8%.该研究可为超声协同其他工艺进行水处理提供放大设计依据. 相似文献
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Organics removal of combined wastewater through shallow soil infiltration treatment: a field and laboratory study 总被引:4,自引:1,他引:3
Soil infiltration treatment (SIT) was proved to be an effective and low-cost treatment technique for decentralized effluents in the areas without perfect sewage systems. Field-scale experiments were conducted under several conditions to assess organics removals through a shallow soil infiltration treatment (SSIT, with effective depth 0.3m) of combined wastewater (discharge from toilets, restaurants and a gas station), while bench-scale soil column experiments were performed in laboratory in parallel to investigate biological and abiological effects of this kind of system. From the start-up to the 10th month, the field SSIT trenches experienced the lowest and highest temperatures of the operation period in Shanghai and exhibited effective organics removals after maturation, with the highest removal rate 75.8% of chemical oxygen demand (COD), highest ultraviolet absorption at 254 nm (UV(254)) decrease by 67.2% and 35.2-100% removals of phenolic and phthalate pollutants. The laboratory results indicated that more organics could be removed in room-temperatured (25+/-2 degrees C) SSIT systems under different influent COD concentrations from 45 mg/l to 406 mg/l, and the highest total COD removal rate could reach 94.0%, in which biological effect accounted for 57.7-71.9%. The results showed that temperature and hydraulic loading rate were the most important factors influencing the removals of COD and organic pollutants in SSIT. 相似文献