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排序方式: 共有142条查询结果,搜索用时 15 毫秒
1.
John M. Jewell James Jaganathan Ishwar D. Aggarwal 《Journal of the American Ceramic Society》1991,74(4):788-796
The effect of controlled heterogeneous nucleation by platinum on the crystallization of a ZrF4 -BaF2 -LaF3 -AlF3 -NaF (ZBLAN) glass was studied. Various levels of platinum were incorporated into this glass by a combination of PtCl2 -doping and melting-atmosphere variation. The effect of doping levels and melting conditions on the incorporation of platinum and the subsequent nucleation of crystals was studied by optical microscopy, scanning electron microscopy, differential scanning calorimetry (DSC), and X-ray diffraction. Increased platinum in the glass resulted in an increased number of nucleation sites for the growth of β-ZrF4 -BaF2 crystals. Analysis of isothermal and ramp-rate DSC measurements indicated that the crystallization of this glass changed from surface controlled to bulk controlled with an increased number of nuclei. This was confirmed by optical microscopy. In addition, Avrami analysis of the isothermal crystallization data gave an accurate approximation of the number of nuclei in the glass. 相似文献
2.
提出以硼酸作为解蔽剂,FereneS作显色剂,直接测定氟化和氟酸盐中杂质铁量的方法。 相似文献
3.
Ziyang Jia Rui Ding Wujiang Yu Yi Li Ailin Wang Miao Liu Feng Yang Xiujuan Sun Enhui Liu 《Advanced functional materials》2022,32(1):2107674
Herein, a trimetallic Ni–Co–Zn perovskite fluoride (ABF3) (denoted as KNCZF) electrode material is explored for advanced aqueous supercabatteries (ASCBs), with KNCZF and activated carbon–FeBiCu@reduced graphene oxides (AC–FeBiCu@rGO) as cathode and anode, respectively, which outperform aqueous supercapacitors (ASCs) and batteries (ABs) with AC and FeBiCu@rGO anodes because of the synergistic effect of pseudocapacitive (KNCZF), capacitive (AC), and faradaic (FeBiCu@rGO) responses. One of the important findings is that the KNCZF shows a typical bulk phase conversion mechanism for charge storage in the alkaline media with the transition of ABF3 perovskite nanocrystals into amorphous metal oxides/(oxy)hydroxides nanosheets, showing the redox-active and redox-inert roles for the Ni/Co and Zn species, respectively, which can be deduced by various ex-situ techniques. Another interesting finding is that the redox-inert Zn species largely enhance the activity of Ni/Co redox-active species in the ABF3 materials, mainly owing to the promotion of surface electroactive sites, adsorption of OH?, and charge transfer of surface Ni/Co atoms by Zn-doping, which can be proved by ex-situ characterizations and theoretical calculations. Overall, this study reveals the structure–activity relationship and charge storage mechanisms of Zn-doping ABF3 materials for advanced ASCBs, showing a great impact on developing advanced electrochemical energy storage. 相似文献
4.
Uri Cohen 《Journal of Electronic Materials》1977,6(6):607-643
Electrodeposition of both epitaxial and polycrystalline continuous films of dense, coherent, and well-adherent silicon coatings
was achieved from molten fluorides. A dissolving Si anode and an operating temperature of about 750 C were utilized. Silicon
electrocrystallization epitaxy (ECE) produced films with the (111) orientation on Si substrates of the same orientation. The
unintentionally doped films were of p-type character with a resistivity in the range 0.05 - 0.10 Ω-cm. Polycrystalline Si
films were similarly electroplated onto various polycrystalline metal substrates. Uniform coherent, and well-adherent coatings
with grain diameters as large as 40 – 50 μm were obtained. The useful rate of electrodeposition of Si could be significantly
increased by the application of an alternating square wave pulse (ASWP)2technique. Cathodic current pulses as high as 300 mA/cm2 (growth rate of about 5 μm/min) were demonstrated. The cathodic current efficiencies, for all modes of growth, were about
70 – 100%. The effects of the various operating parameters, and some prospective applications to the fabrication of solar
cells, are discussed.
This was paper A-6 in the 18th Annual Electronic Materials Conference, Salt Lake City, June 23–25, 1976. 相似文献
5.
电解铝用氟化盐工业状况 总被引:4,自引:0,他引:4
从电解铝市场、氟化盐产能、产量、技术水平等方面,浅析了氟化盐(冰晶石、氟化铝)的现状及发展趋势,对氟化盐的市场做了预测,未来几年内,由于市场竞争更加激烈,环保呼声日见高涨,氟化盐行业的结构调整及技术进步将成为必然趋势。 相似文献
6.
High‐Curie‐Temperature Ferromagnetism in (Sc,Fe)F3 Fluorides and its Dependence on Chemical Valence 下载免费PDF全文
7.
V. V. Sharapova 《Refractories and Industrial Ceramics》2009,50(1):49-51
It is confirmed that an aluminum electrolyzer casing is subject to electrochemical corrosion. It is established that on reaction
of electrolyzer associated gaseous products with the electrolyzer casing there is formation of fluorides of bi- and trivalent
iron, and also iron fluorides of non-stoichiometric composition. It is shown that the fluoride layer formed does not protect
the casing surface from further corrosion. In order to protect the electrolyzer casing it is necessary to fasten a refractory
barrier layer. More reliable heat insulation should be used in order to maintain the optimum casing heating temperature.
Translated from Novye Ogneupory, No. 1, pp. 39 – 42, January 2009. 相似文献
8.
以偏钒酸铵为原料,采用"煤气还原+原位烧结"工艺制备高活性V_2O_3阴极片,在氟化物体系熔盐中实现了快速电脱氧制备金属钒,并通过测定循环伏安曲线结合恒电位电解实验,研究了电解过程的反应机理。结果表明:V_2O_3在氟化物熔盐中可实现快速电脱氧,电解4 h后所得金属钒的氧含量降至0.218%(质量分数,下同);V_2O_3阴极电脱氧产生的O~(2-)在脱氧反应区可原位生成铝氧氟络合离子并进一步产生金属铝,从而引发阴极的铝热还原反应,导致V_2O_3熔盐电脱氧过程同时存在直接电还原反应和铝热还原反应,其中后者起着关键的加速作用;在熔盐中添加适量Al_2O_3可强化V_2O_3电脱氧过程,在其他条件不变的情况下电脱氧时间可缩短至3 h。 相似文献
9.
熔盐反应堆是一种以熔融盐为冷却剂和核燃料的反应堆。作为6种第四代核电站概念堆之一,熔盐堆正日益受到人们的关注。材料的腐蚀问题是熔盐堆发展过程中面临的一个技术挑战。为此,相关研究机构开展了大量研究,并取得了积极进展。本文对材料在熔融氟化物中的腐蚀机制、腐蚀行为以及抗蚀材料发展现状等方面的研究进行了综述。 相似文献
10.
BaCuQF (Q=S, Se, Te) materials exhibit band gaps that allow transmission of much of the visible spectrum. BaCuSF is transparent in thin-film form with a band gap of 3.1 eV. Band gap estimates for powders of the solid solution series BaCuS1−xSexF were obtained from wavelength-dependent diffuse-reflectance measurements using an integrating sphere. The band gap can be tuned by the substitution of Se for S to 2.9 eV for BaCuSeF. The decrease scales almost linearly with the increase in the volume of the tetragonal unit cell, which is determined primarily by the expansion of the a lattice parameter; the overall volume increase is 7.0% from x=0 to 1. Further reduction of the band gap is observed in BaCuSe1−xTexF solid solutions, where a unit cell volume increase of 5.5% produces a band gap of 2.7 eV in BaCuSe0.5Te0.5F. Powders and films of BaCuSF exhibit strong red luminescence under ultraviolet excitation, which is suppressed by K doping. Additional tuning of band gap and electrical properties (the materials are p-type conductors) can be achieved by replacing Ba with Sr. 相似文献