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91.
采用循环伏安法和恒电位电解法,探讨了含有ZnCl2的乙睛水混合溶液中五氯吡啶(PCP)在不锈钢阴极表面电还原脱氯生成2,3,5,6-四氯吡啶(2,3,5,6-TCP)的反应机理;采用恒电流电解法对该电还原脱氯过程的各种工艺条件进行了优化。结果表明:该体系中PCP电还原脱氯生成2,3,5,6-TCP主要遵循以Zn/Zn2+为氧化还原媒介的间接电还原机理;优化工艺条件下(阴极液含0.025mol·L-1HCl+15%(体积分数)水+0.2mol·L-1苯磺酸钠+0.16mol·L-1ZnCl2的乙腈溶液;电流密度为1.25A·dm-2),0.08mol·L-1PCP能高选择性地脱氯生成2,3,5,6-TCP,2,3,5,6-TCP的收率和电解电流效率分别可达88.7%和59.1%。  相似文献   
92.
Wine is one of the most popular alcoholic beverages in the world, although it is mainly consumed in European and South American countries. Several thousand years have passed since the product of grape fermentation was accidentally discovered. Over the last 100–150 years, winemaking has been completely revolutionized in terms of procedures and equipment. This work is aimed to give a comprehensive overview of the consolidated use of winemaking innovations that are still in the development stage or already applied to commercial products. Their effects on physical, chemical, and sensory characteristics of wines will also be discussed in comparison with the consolidated vinification procedures.  相似文献   
93.
硝酸羟胺是Purex流程钚纯化过程的还原剂。本文建立了30%TBP/正十二烷体系中硝酸羟胺还原反萃Pu(Ⅳ)的单级迭代计算数学模型,并提出了相应的数学算法,编写了模拟连续逆流萃取器中的一级的计算机模拟程序,使用文献数据对模型和程序进行了验证。结果表明:模型计算值与文献实验值符合良好;本文模型计算结果的准确度高于文献模型。最后分析了计算时间单元长度对准确度的影响。  相似文献   
94.
 为找到合理有效的炉渣排氯制度,使得炉渣排氯能力最大化,在对高炉内氯元素进行热力学分析的基础上,研究了高炉渣的化学成分、温度以及恒温时间对排氯能力的影响。结果表明,高炉渣的排氯率随着炉渣碱度的提高而增加;其排氯率随温度的增加而降低;随[w(MgO)]的增加,其排氯率先增加后降低;随[w(Al2O3)]的增加,其排氯率先增加,当渣中[w(Al2O3)]超过16%时,其对炉渣排氯率的影响不大;随着恒温时间的延长,炉渣的排氯率降低。高炉在保证正常生产的前提下,应适当地提高炉渣碱度,降低高炉渣温度和增加出渣铁次数,[w(MgO)]和[w(Al2O3)]应保持在11.0%和16.0%左右,以提高炉渣的排氯能力,减少氯元素对高炉冶炼和后续设备产生的不利影响。  相似文献   
95.
Ion-exchange equilibrium between Cs and H on a sulfonated polystyrene resin of Dowex 50W with 8% crosslinking has been studied over a temperature range of 25°to 60°C, using 137Cs as radioactive tracer; the various experimental data related to the equilibrium experiments were examined in detail by several different methods; a new treatment to take into account the water uptake in the exchange system Cs-H was also applied with the aid of a radioactive tracer technique. The thermodynamic equilibrium constant Kcs H determined by the present study compares well with the values calculated indirectly from experimental data found by other investigators. Data are also given for the heats, free energies and entropies of the exchange reaction involving Dowex 50W. Fairly good results have been obtained on the exchange of Cs and H.  相似文献   
96.
An evaluation is made of the reactivity control capability of the fuel processing system (FPS) in a molten-salt breeder reactor. The principal functions required of the FPS are : (a) Isolation of 233Pa from regions of high neutron flux during its decay to 233U, and (b) the removal of fission products from the system. The FPS can very usefully serve also to control the primary system reactivity by appropriately utilizing its function of extracting uranium and reconstituting the fuel contained in the salt. The principles of operation are quite similar to the chemical shim control system currently installed in PWR's whereby the core reactivity, affected by changes in the moderator temperature, fuel burnup and transient Xe, is adjusted by regulating the concentration of boric acid introducted in the moderator as neutron absorber. The present study examines the capability of the FPS to follow transient Xe as in PWR's, and proves that the FPS should effectively serve as a system for adjusting not only long-term changes in reactivity but also short-term transient variations without any accompanying difficulties foreseen in operation.  相似文献   
97.
This study is related to the development of a suitable mixture of citric acid, EDTA and ascorbic acid (CEA) for dissolving the haematite deposited on the structural surfaces of cooling water circuits in BWRs. The dissolution experiments were performed with synthetically prepared haematite. The dependence of the dissolution rates on each of the constituents of the mixture has been evaluated using a ‘grain model’. It was found to be Langmuirianin the case of citric acid, linear in the case of EDTA and independent of ascorbic acid concentration. The ratio of molar concentration of the ligand to the total iron was varied from 0.5—2.5. Activation energy of the dissolution in a CEA mixture having stoichiometrically excess EDTA has been determined by performing experiments upto 353 K. The highest dissolution was obtained in 11:44:4 mol·m?3 and 2:55:4 mol·m?3 CEA mixtures.  相似文献   
98.
HIV cell fusion and entry have been validated as targets for therapeutic intervention against infection. Bicyclams were the first low-molecular-weight compounds to show specific interaction with CXCR4. The most potent bicyclam was AMD3100, in which the two cyclam moieties are tethered by a 1,4-phenylenebis(methylene) bridge. It was withdrawn from clinical trials owing to its lack of oral bioavailability and cardiotoxicity. We have designed a combinatorial library of non-cyclam polynitrogenated compounds by preserving the main features of AMD3100. At least two nitrogen atoms on each side of the p-phenylene moiety, one in the benzylic position and the other(s) in the heterocyclic system were maintained, and the distances between them were similar to the nitrogen atom distances in cyclam. A selection of diverse compounds from this library were prepared, and their in vitro activity was tested in cell cultures against HIV strains. This led to the identification of novel potent CXCR4 coreceptor inhibitors without cytotoxicity at the tested concentrations.  相似文献   
99.
三氯乙酸在活性银阴极上的电还原脱氯   总被引:2,自引:1,他引:1       下载免费PDF全文
采用循环伏安法和恒电流电解法研究了碱性水溶液中三氯乙酸在活性银阴极上的电化学还原脱氯反应。实验结果表明:活性银阴极对三氯乙酸的还原脱氯反应具有很高的电催化活性,三氯乙酸在银电极上的还原反应是个分步脱氯过程,主要的路径为三氯乙酸--二氯乙酸--氯乙酸--乙酸。  相似文献   
100.
Trichloroethene (TCE) is a common and recalcitrant contaminant in groundwater. Microbially catalyzed reductive dechlorination is a dominant pathway for TCE degradation, in which substrates and electron donors are essential. In this study, extraneous electron supplementation was attempted to enhance reductive dechlorination of TCE and its derivatives. Reactors were established with groundwater containing TCE, and a 6-V battery was used to supply an average current of 29 μA of dc power to feed electrons to the microcosms. We measured 80–90% depletion of TCE within 70 d in reactors (both sterile and non-sterile) containing 300–400 μg TCE/l and from 97 to 98% depletion in microcosms containing 10 mg TCE/l. No intermediate products such as dichloroethylene or vinyl chloride were detected during this study. Results demonstrate that electron-supplemented degradation of TCE appears to be an abiotic process that is unassociated with microbial populations or indigenous redox conditions. No apparent accumulation of TCE daughter products were observed and overall efficiency of this electroremediation process was calculated to be 6.9 g TCE degraded/kW h. This efficiency would make electron supplementation an attractive alternative to the substrate-amended biological reductive dechlorination of TCE.  相似文献   
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