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排序方式: 共有91条查询结果,搜索用时 10 毫秒
1.
我国磁选设备及铁矿石预选技术 总被引:1,自引:0,他引:1
《工程设计与建设》1996,(6)
介绍了目前我国磁选设备的研制及应用现状,并就干式弱磁选、强磁选和重选等工艺用于我国铁矿石预选的技术经济状况及推广应用价值进行了论述。 相似文献
2.
The application of 1,9-nonanedithiol (NDT) self-assembled monolayer (SAM) on gold for the electrochemical determination of Cd2+ was studied. Interestingly, we found that a NDT SAM strongly affects the stripping wave of Cd, resulting in a sharp peak that was used for electroanalytical determination of Cd2+ in aqueous solutions. The different parameters, such as potential and time of deposition of Cd, were examined. Furthermore, polarization-modulated infrared reflection absorption spectroscopy (PM IRRAS) and X-ray photoelectron spectroscopy (XPS) were used for exploring the interaction between the deposited Cd and the thiol groups on Au. FTIR measurements clearly indicate that NDT is assembled in a disordered liquid type monolayer interacting with the Au electrode via both thiol moieties. XPS reveals that Cd is stripped at two different potentials and that the signal of sulfur is almost unchanged by deposition and desorption of Cd. All these finding allude to the interesting conclusion that Cd is deposited on Au lifting to some extent the thiol groups. 相似文献
3.
The use of chemically modified silica gel N-(1-carboxy-6-hydroxy) benzylidenepropylamine (SiG-CHBPA), ion exchanger for removal and preconcentration of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb in natural water samples collected from River Nile, Mediterranean Sea and other locations followed by their consecutive AAS determination was described. The effects on the percentage of recovered metal ions including mass change of ion exchanger, stirring time, pH of sample solutions and eluent concentration were studied. The distribution coefficient Kd, ml g− 1 and the percentage concentration of the studied metal ions on the ion exchanger at equilibrium, CM,eqm ,% (Recovery, %) were studied as a function of experimental parameters. The logarithmic values of the distribution coefficients, log Kd are 3-6.3. The interfering effects of some foreign ions on the removal, preconcentration and determination of the investigated metal ions were described. The metal-chelates formed between the ion exchanger and the studied metal ions were characterized by IR (absorption and reflectance), UV spectrometry, potentiometric titration and thermal analysis (TG and DTG). The reliability of the present method was confirmed by the comparison with a standard solvent extraction method. The present method is simple and rapidly applicable for the determination of the studied metal ions, ng ml− 1 in different natural water samples. 相似文献
4.
Adsorbent and corrosion resistant films are useful for sensor development. Therefore, the aim of this work is the production and characterization of plasma polymerized fluorinated organic ether thin films for sensor development. The polymerized reactant was methyl nonafluoro(iso)butyl ether. Infrared Spectroscopy showed fluorinated species and eventually CO but CHn is a minor species. Contact angle measurements indicated that the film is hydrophobic and organophilic but oleophobic. Optical microscopy reveals not only a good adherence on metals and acrylic but also resistance for organic solvents, acid and basic aqueous solution exposure. Double layer and intermixing are possible and might lead to island formation. Quartz Crystal Microbalance showed that 2-propanol permeates the film but there is no sensitivity to n-hexane. The microreactor manufactured using a 73 cm long microchannel can retain approximately 9 × 10−4 g/cm2 of 2-propanol in vapor phase. Therefore, the film is a good candidate for preconcentration of volatile organic compounds even in corrosive environment. 相似文献
5.
放射性示踪技术研究金,铂在新型大孔树脂HHY—10A上的离子交换行为 总被引:7,自引:1,他引:7
应用195mPt、199Au放射性示踪剂研究了金、铂在一种新研制的大孔强碱性阴离子交换树脂上的离子交换行为。系统研究了吸附和洗脱的条件,包括吸附介质的成分和酸度、洗脱剂以及吸附和洗脱流速的影响等。应用此法从标准参考物质DZΣ-1、DZΣ-2中分离和浓集出Au、Pt,用ICP-MS测定,分析结果与推荐值符合良好。 相似文献
6.
白云鄂博中贫氧化矿弱磁-强磁-浮选联合流程综合回收稀土研究 总被引:3,自引:0,他引:3
本文洋细分析讨论了采用弱磁—强磁—浮选工艺流程,稀土矿物的分选行为和规律,认为强磁选作业能有效地将磁性很弱的稀土矿物预先富集在强磁中矿。强磁中矿与其它流程浮选稀土的原料相比,具有矿物组成简单,未受药剂污染、且基本无细泥的优点,通过浮选易于获得高品位的稀土精矿,并使稀土回收率有较大幅度的提高。该工艺流程选别稀土具有技术先进,经济合理的特点。 相似文献
7.
Separation/preconcentration of copper and cadmium using TiO(2) core-Au shell nanoparticles modified with 11-mercaptoundecanoic acid and their slurry analysis by flame atomic absorption spectrometry were described. For this purpose, at first, titanium dioxide nanoparticles were coated with gold shell by reducing the chloroauric acid with sodium borohydride and then modified with 11-mercaptoundecanoic acid. The characterization of modified nanoparticles was performed using ultra-violet spectroscopy and dynamic light scattering. Copper and cadmium were then collected on the prepared sorbent by batch method. The solid phase loaded with the analytes was separated by centrifugation and the supernatant was removed. Finally, the precipitate was slurried and directly aspirated into the flame for the determination of analytes. Thus, elution step and its all drawbacks were eliminated. The effects of pH, amount of sorbent, slurry volume, sample volume and diverse ions on the recovery were investigated. After optimization of experimental parameters, the analytes in different certified reference materials and spiked water samples were quantitatively recovered with 5% RSD. The analytes were enriched up to 20-fold. Limits of detection (N=10, 3σ) for copper and cadmium were 0.28 and 0.15 ng mL(-1), respectively. 相似文献
8.
2-Aminothiazole covalently attached to a silica gel surface was prepared in order to obtain an adsorbent for Hg(II) ions having the following characteristics: good sorption capacity, chemical stability under conditions of use, and, especially, high selectivity. The accumulation voltammetry of mercury(II) was investigated at a carbon paste electrode chemically modified with silica gel functionalized with 2-aminothiazole (SIAMT-CPE). The repetitive cyclic voltammogram of mercury(II) solution in the potential range −0.2 to +0.6 V versus Ag/AgCl (0.02 mol L−1 KNO3; v=20 mV s−1) show two peaks one at about 0.1 V and other at 0.205 V. The anodic wave peak at 0.205 V is well defined and does not change during the cycles and it was therefore further investigated for analytical purposes using differential pulse anodic stripping voltammetry in differents supporting electrolytes. The mercury response was evaluated with respect to pH, electrode composition, preconcentration time, mercury concentration, “cleaning” solution, possible interferences and other variables. The precision for six determinations (n = 6) of 0.02 and 0.20 mg L−1 Hg(II) was 4.1 and 3.5% (relative standard deviation), respectively. The detection limit was estimated as 0.10 μg L−1 mercury(II) by means of 3:1 current-to-noise ratio in connection with the optimization of the various parameters involved and using the highest-possible analyser sensitivity. 相似文献
9.
Yunus Emre Unsal Mustafa Soylak Mustafa Tuzen 《International Journal of Food Science & Technology》2012,47(6):1253-1258
A new and simple solid‐phase extraction method for the determination of trace levels of sunset yellow has been developed on Diaion HP 2MG column system. The adsorbed sunset yellow on the resin was eluted with 3 mL of methanol and determined by UV–Vis spectrophotometry at 484 nm. Various experimental parameters such as pH, amount of sunset yellow, flow rates of sample and eluent solutions, resin amount, sample volumes, etc. were investigated. The influences of some alkali, alkali earth and transition metals on the recoveries of sunset yellow were investigated. The recovery values for sunset yellow were higher than 95%. Preconcentration factor was found as 150. The detection limit (three sigma) of the reagent blank for sunset yellow was 5.2 μg L?1. The relative standard deviations (RSD) of the procedure were found as 3.9%. The validation of the presented procedure was performed by the method of standard addition. The procedure was successfully applied to the determination of trace levels of sunset yellow in powdered beverage and confectionery products. 相似文献
10.
Near infrared sensors can be a very useful technique for the qualitative analysis of complex ores, and thus could be useful for the preconcentration of ores. In this paper, individual particles of hydrothermally-formed copper ore sampled from a mine in the Los Pozos mining district, northern Chile, were classified as product, middling and waste based on their near infrared response. The classification of copper bearing minerals (product) from gangue (waste) was considered for vibration combination bands at longer wavelengths from 2000 to 2400 nm. This region exhibits characteristic features for carbonates and hydroxyl gangue bearing minerals. The near infrared features at 1400 and 1900 nm were not considered favourable for classification and subsequent discrimination because they can be influenced by moisture and other environmental factors and are easily suppressed by iron-rich minerals.Two near infrared preconcentration strategies were applied for particle discrimination. Results indicate that targeting only the calcite (carbonate) dominated particles for discrimination as waste provided the best option for preconcentration. The near infrared discrimination analysis correlates well with mineralogical (QEMSCAN® and XRD) and elemental (XRF) data classification. The results indicate that near infrared spectroscopy is a suitable preconcentration method for supergene copper ore. 相似文献