全文获取类型
| 收费全文 | 1639篇 |
| 免费 | 11篇 |
| 国内免费 | 93篇 |
专业分类
| 电工技术 | 2篇 |
| 综合类 | 14篇 |
| 化学工业 | 438篇 |
| 金属工艺 | 386篇 |
| 机械仪表 | 30篇 |
| 建筑科学 | 4篇 |
| 矿业工程 | 45篇 |
| 能源动力 | 143篇 |
| 武器工业 | 1篇 |
| 无线电 | 21篇 |
| 一般工业技术 | 355篇 |
| 冶金工业 | 215篇 |
| 原子能技术 | 17篇 |
| 自动化技术 | 72篇 |
出版年
| 2024年 | 48篇 |
| 2023年 | 203篇 |
| 2022年 | 98篇 |
| 2021年 | 52篇 |
| 2020年 | 108篇 |
| 2019年 | 147篇 |
| 2018年 | 51篇 |
| 2017年 | 74篇 |
| 2016年 | 53篇 |
| 2015年 | 46篇 |
| 2014年 | 85篇 |
| 2013年 | 72篇 |
| 2012年 | 39篇 |
| 2011年 | 28篇 |
| 2010年 | 24篇 |
| 2009年 | 39篇 |
| 2008年 | 21篇 |
| 2007年 | 38篇 |
| 2006年 | 38篇 |
| 2005年 | 21篇 |
| 2004年 | 19篇 |
| 2003年 | 37篇 |
| 2002年 | 29篇 |
| 2001年 | 35篇 |
| 2000年 | 30篇 |
| 1999年 | 28篇 |
| 1998年 | 7篇 |
| 1994年 | 16篇 |
| 1993年 | 11篇 |
| 1992年 | 15篇 |
| 1991年 | 10篇 |
| 1990年 | 10篇 |
| 1989年 | 6篇 |
| 1988年 | 21篇 |
| 1987年 | 26篇 |
| 1986年 | 23篇 |
| 1985年 | 10篇 |
| 1984年 | 8篇 |
| 1983年 | 5篇 |
| 1982年 | 6篇 |
| 1980年 | 5篇 |
| 1979年 | 6篇 |
| 1978年 | 9篇 |
| 1975年 | 5篇 |
| 1974年 | 12篇 |
| 1972年 | 6篇 |
| 1971年 | 5篇 |
| 1970年 | 5篇 |
| 1966年 | 14篇 |
| 1962年 | 6篇 |
排序方式： 共有1743条查询结果，搜索用时 15 毫秒
991.
992.
A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. Thermal cycling behavior of NiCoCrAlY-4 YSZ thermal barrier coatings(TBCs) with and without Pt modification was evaluated in ambient air at 1100?C up to 1000 cycles, aiming to investigate the effect of Pt on formation of thermally grown oxide(TGO) and oxidation resistance. Results indicated that a dual layered TGO, which consisted of top(Ni,Co)(Cr,Al)_2O_4 spinel and underlying α-Al_2O_3, was formed at the NiCoCrAlY/4 YSZ interface with thickness of 8.4μm, accompanying with visible cracks at the interface. In contrast, a single-layer and adherent α-Al_2O_3 scale with thickness of 5.6μm was formed at the interface of Pt-modified NiCoCrAlY and 4 YSZ top coating. The modification of Pt on NiCoCrAlY favored the exclusive formation of α-Al_2O_3 and the reduction of TGO growth rate, and thus could effectively improve overall oxidation performance and extend service life of TBCs. Oxidation and degradation mechanisms of the TBCs with/without Pt-modification were discussed. 相似文献
993.
《Minerals Engineering》2003,16(9):873-875
This technical contribution is aimed at studying the physicochemical properties of cashew gum as well as its performance as a limestone depressor during the phosphate minerals flotation. Cashew gum and starch characterizations were accomplished by identifying their functional groups through infrared spectroscopy. After that, some physicochemical properties of calcite were investigated, having cashew gum as a depressant, by using microflotation and flotation techniques.It was observed, by comparing the infrared spectra of both substances, that one was dealing with quite similar structures. The microflotation tests showed that flotability decreases as the cashew gum or starch concentrations increase.The flotation of limestone confirms the depressing power of cashew gum, showing that it is possible to reduce the insoluble residues (IR) from 10.5%, in the original ore, to near 0.6% with carbonate recovery in the range of 70–80%. 相似文献
994.
《Minerals Engineering》2002,15(8):573-576
As a case study to quantify the flotation response, Cu activation of pyrite was examined. Two particle sizes, 106/150 and 37/74 μm (surface area 304 and 901 cm2/g), were used. Micro-flotation was performed to determine the rate constant, k, as a function of surface concentration of copper, [Cu]surf. The [Cu]surf was determined by EDTA extraction and controlled by contact with Cu salt solution or with chalcopyrite and chalcocite particles. The rate constant relative to zero copper, kCu/k0, followed the same trend against [Cu]surf for both particle sizes. Chalcocite gave a surface concentration about 40 times higher than chalcopyrite, corresponding to their relative ion production (the b-values in Part I). An estimate of mineral grade likely to cause activation was made assuming the grade was inversely dependent on b and taking the critical grade of chalcocite as 0.1% (Petruk, 2000). This gave a critical chalcopyrite grade of ca. 2%. 相似文献
995.
《Minerals Engineering》2006,19(2):172-179
Lead and copper activation of pyrite in the presence of thiol collectors was examined by means of cyclic voltammetry and microflotation techniques. Di-isobutyl dithiophosphinate (Aerophine 3418A) and alkyl thionocarbamate (AERO 3894) were employed as collector of lead and copper, respectively. Otherwise, isopropyl xanthate (IPX) was also used as a collector of both: lead and copper. The results revealed that in the presence of non-conventional collectors, the increase in pyrite recovery due to the activation by copper and lead species, was noticeably smaller than that exhibited when xanthate (IPX) was used. The electrochemical response of pyrite indicates that lead activation favors the formation of dixanthogen. In non-xanthate systems, the voltammograms of pyrite remained unaffected regardless of the activation by lead or copper species. 相似文献
996.
《Minerals Engineering》2006,19(13):1397-1400
Pelleting flocculation can be viewed as a technique that improves the sludge characteristics, which may be beneficial during the subsequent phase of solid–liquid separation. Generated flocs structures possess an appearance of nearly spherical beads with an enhanced stability.The literature provides two theoretical growth models of such pellet-like flocs: (i) series and (ii) parallel system. The parallel system concerns the formation of aggregates with a high degree of structural order that is called onion-like structure. Consequently, in reported cases of pelleting flocculation this kind of internal buildup of flocs was strongly suggested. Contrary to these statements, the reasoning presented here demonstrates that the predominantly non-uniform interior structure of pellet flocs, here termed raspberry-like structure, is the result of sludge conditioning by pelleting flocculation.The goal of this paper is to present and discuss the structural attributes of pellet floc aggregates in terms of internal buildup and to reorder the available literature on pelleting flocculation according to the proposed reinterpretation of the concepts of this technique. 相似文献
997.
《Fuel》1987,66(6):779-784
The loss of organic material into the aqueous and gas phases in the liquefaction of raw peat with ≈ 90 wt% moisture content has been studied. The raw material was treated with CO at an initial pressure of 5.5–8.3 MPa and a temperature of 300–350 °C in the presence of K2CO3. The yield of water, water-soluble and gas products depended on the operating conditions and the chosen input material. In the liquefaction of peat with 31 wt% oxygen content the loss of material into the aqueous and gas phases decreased with increases in the initial CO pressure and the reaction temperature. The loss of organic material from peat with a high oxygen content (≈ 40 wt%) was significant. This loss of organic material is a result of thermal decomposition and hydrolysis of the organic matter of the peat and elimination of low molecular weight gases and water-soluble compounds with high oxygen and low energy contents. The selective transfer of highly oxygenated components from the peat resulted in the formation of liquid and solid residual materials with low oxygen and high energy contents. Most of the energy content of the peat becomes concentrated in the liquid and solid products (toluene- or acetone-solubles and -insolubles). The loss of organic material from the peat into the aqueous and gas phases is not accompanied by significant energy losses from the raw material. 相似文献
998.
《Ceramics International》1987,13(2):109-112
Y-PSZ (partially stabilized zirconia) and Y-TZP (tetragonal zirconia polycrystals) containing from 1·5 to 5·0 mol% Y2O3 were prepared by hot isostatic pressing. The KIC value nonlinearly increases with the decrease from 2·5 to 2·0 mol % Y2O3, and has a maximum KIC value of 20 MPa √m at 2·0 mol% Y2O3. In order to clarify the toughness creating mechanism of the above materials, the experimental results of KIC, σf and transformation zone size were examined, with emphasis on Y2O3 composition, Al2O3 additives and grain size. 相似文献
999.
《Acta Metallurgica》1975,23(6):779-781
It is argued that transgranular mass transfer and grain-boundary sliding are inter-dependent deformation processes and can in no sense make separate contributions to the total diffusion creep strain. Macroscopic strain can be related either entirely to grain shape changes or totally to sliding displacements. This is corroborated by interpretation of some experimental data obtained on magnesium-0.8w t. % manganese deformed in diffusion creep. 相似文献
1000.
《Acta Metallurgica》1974,22(7):835-845
The dynamics of nucleation and growth of a thermoelastic martensite in a splat quenched Au-47.5 at.% Cd alloy has been studied utilizing electron microscopy. The high temperature CsCl type β-phase is retained at room temperature by splat quenching. A reversible martensite transformation has been induced in the electron transparent regions of the liquid quenched foils by varying the intensity of the illuminating electron beam while the foil was under observation in the electron microscope. This control over the transformation has permitted a study of the nature and types of martensite nucleation sites, as well as, the crystallography, morphology and growth mechanisms of the martensite embryos in this alloy. The nucleation of the 3R martensite laths is heterogenous. The lath initially appears as a planar feature on a {110}β plane and rapidly increases in thickness until a wedge shape is achieved. Growth of the lath occurs by the propagation of this wedge into the β-phase. The screw dislocation-like nature of this wedge interface is discussed. 相似文献