全文获取类型
收费全文 | 875篇 |
免费 | 8篇 |
国内免费 | 21篇 |
专业分类
综合类 | 1篇 |
化学工业 | 305篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 137篇 |
矿业工程 | 7篇 |
能源动力 | 94篇 |
轻工业 | 85篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
无线电 | 4篇 |
一般工业技术 | 155篇 |
冶金工业 | 69篇 |
原子能技术 | 33篇 |
自动化技术 | 7篇 |
出版年
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 97篇 |
2012年 | 52篇 |
2011年 | 79篇 |
2010年 | 44篇 |
2009年 | 78篇 |
2008年 | 71篇 |
2007年 | 60篇 |
2006年 | 57篇 |
2005年 | 41篇 |
2004年 | 48篇 |
2003年 | 36篇 |
2002年 | 26篇 |
2001年 | 14篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有904条查询结果,搜索用时 15 毫秒
71.
V. Ponnusami R. Madhuram V. Krithika S.N. Srivastava 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,140(1-3):609-613
The sorption of methylene blue onto untreated guava leaf powder has been studied. The kinetics of sorption of methylene blue is described by pseudo-second-order model. Effects of initial dye concentration, solution temperature, and adsorbent dosage have been studied. The pseudo-second-order rate constant has been correlated as a function of the system variables. Statistical tools like Student's t-test, F-test, ANOVA and lack of fit have been employed to determine the significance of each coefficient that appeared in the model. Model adequacy has been checked by residual distribution. The proposed model explains 95.1% of the total variation in the response. 相似文献
72.
A model for the global dynamics of a sorption heat pump is presented in this work. It involves a model of a reactor where gas-solid reaction takes place coupled with a model of a two-phase closed thermosyphon cooling exchanger. Simulations of the whole discontinuous cold production process have been performed. The good agreement between experimental and simulation data shows the ability of the present model to accurately represent the dynamics of such systems. An analysis of the physical mechanisms governing the dynamics of each process stage is made. It was shown that mass limitation strongly slowed down the synthesis when the other phases of the process are mainly dependent on the thermal behavior of the transformer. This model can be used as a powerful tool for the optimization of sorption systems and for the intensification of such processes. 相似文献
73.
Danny C.K. Ko 《Chemical engineering science》2005,60(20):5472-5479
The ability of bone char to adsorb three metal ions, namely, cadmium, copper and zinc, from effluents in fixed beds has been studied. Two binary metal ion sorption systems, Cd+Cu and Cu+Zn, have been investigated. The variables studied include metal ion solution flowrate, initial metal ion concentration, and bone char particle size bed height. The experimental breakthrough curves for each binary system were measured at five bed heights.A multicomponent film-surface diffusion model has been developed to predict the breakthrough curves by incorporating the IAS for both the Langmuir and the Sips equations, since they both correlate the single component equilibrium isotherm data well. A novel development is the modification of the solution methodology, previously restricted to a constant diffusivity, to incorporate a variable diffusivity correlated with adsorbent coverage by the constant self-diffusivity. The self-diffusivities for the metal ions have been evaluated. 相似文献
74.
For preparation of solid oxide fuel cell functional anode (Ni-YSZ) by electroless deposition technique, surface adsorption of metallic palladium (Pd0) on zirconia is the most important step during the sensitization process. For the sensitization process, the initial reaction kinetics are based on external mass transfer followed by intra-particle mass transfer phenomena. A kinetic model for the reversible sorption of Pd0 on zirconia is developed that incorporates an effectiveness factor (η) which estimates the extent of intra-particle mass transfer. Based on the proposed model, an expression for Pd0 uptake at equilibrium (p), an important property of YSZ, is developed. The theoretical kinetic model proposed is verified with experimental parameters like electrical properties of these functional anodes prepared under various sensitization conditions, e.g., agitation frequencies, equilibration time etc. Due to intra-particle mass transfer, the concentration gradient of Pd0 from the surface of YSZ to bulk is minimized which favours uniform deposition of Ni on YSZ. Consequently, during subsequent electroless deposition of metallic Ni, the concentration gradient of the same is reduced from the bulk to the YSZ surface and results in enhanced functionality in the cermet anode. The validation is correlated with the electrical properties and surface morphologies of these functional cermets. 相似文献
75.
The Co2+ sorption of two wool powders was investigated using its radioisotope 57Co (T1/2 = 271.8 days and γ = 122.1 and 136.5 keV) as a tracer. The effects of the type of buffer, the pH value, the contact time and the initial concentration of Co2+ on the sorption behaviour of wool powders were studied. The Co2+ releasing ability of wool powders and the re-use of wool powders to sorb Co2+ were also examined. The optimum sorption of Co2+ by the powders occurred at pH 8 in phosphate buffer and pH 10 in ammonium sulphate buffer. Fourier-transform infrared spectroscopy (FTIR) was used to study the changes in chemical structure of the wool after exposure to both buffer solutions. Compared to the untreated wool fibre, the fine wool powders showed rapid sorption rates and high sorption capacities for Co2+. Co2+ ions were recovered after exposing the Co2+ loaded wool to HCl (0.1 M) and buffer at pH 3 (glycine/sodium chloride). After releasing Co2+ ions from wool powders, the efficiency of wool powders re-used to sorb Co2+ was 80% of that of the fresh wool powders. It is concluded from this study that wool powder can be used as an efficient sorbent to remove and release Co2+ from solution. 相似文献
76.
Nashaat N. Nassar Maen M. Husein Pedro Pereira-Almao 《Fuel Processing Technology》2010,91(2):169-3965
During steam assisted gravity drainage for heavy oil recovery aqua-thermolysis reactions take place, whereupon gaseous hydrogen sulfide, H2S(g), is produced. A method to capture H2S(g) and convert it into a chemically inactive species is deemed necessary for sustaining in-situ recovery and upgrading. Part I of the current study explored the formation and stabilization of colloidal FeOOH particles in heavy oil matrices. In this Part, we evaluate the H2S(g) sorption ability of these particles as well as other metal oxide/hydroxide particles. Furthermore, the effect of mixing and temperature on H2S(g) sorption was investigated. Results showed that the rate and capacity of H2S(g) sorption increased as the concentration of FeOOH increased. Mixing, on the other hand, had insignificant effect on the sorption capacity, however it improved the sorption kinetics. In addition, in-situ prepared colloidal particles showed better reactivity towards H2S(g) than commercial α-Fe2O3 nanoparticles. Temperature had an adverse effect on the H2S(g) sorption capacity of FeOOH. This was attributed to a change in chemical structure of FeOOH as the temperature increased. Nevertheless, in-situ prepared ZnO colloidal particles completely removed H2S(g) even at high temperatures. 相似文献
77.
Elimination of beta-blockers in sewage treatment plants 总被引:2,自引:0,他引:2
beta-Blockers are used to treat high blood pressure as well as patients recovering from heart attacks. In several studies, they were detected in surface water, thus indicating incomplete degradability of these substances in sewage treatment plants (STPs). In this study, we determined the sorption coefficients (K(D)) and degradation rates of the four beta-blockers sotalol, atenolol, metoprolol and propranolol in sludge from an STP operating with municipal wastewater. The sorption coefficients (K(D), standard deviations in brackets) were determined as 0.04(+/-0.035), 0.04(+/-0.033), 0.00(+/-0.023) and 0.32(+/-0.058) Lg(-1)(COD), and the pseudo-first-order degradation rate constants were estimated to be 0.29(+/-0.02), 0.69(+/-0.05), 0.58(+/-0.05) and 0.39(+/-0.07) Ld(-1)g(-1)(COD) for sotalol, atenolol, metoprolol and propranolol, respectively. These values translate into a typical elimination in STPs (sludge concentrations of 4g(COD)L(-1) and a hydraulic retention time of 6h) of 25%, 37%, 44% and 50% for sotalol, propranolol, metoprolol and atenolol, respectively. These results are also confirmed by measurements in two municipal STPs for atenolol, sotalol and propranolol. The estimated eliminations are slightly too high for metoprolol. 相似文献
78.
When white chocolates are kept molten in storage tanks, problems can arise due to uncontrolled thickening and solidifying of the chocolate mass. The thickening of molten white chocolate was simulated on a laboratory scale using a rotational rheometer under static conditions, interrupted by short shear periods to measure the increasing viscosity. Several chocolates having different dairy components and fat contents were investigated for their tendency to thicken. In addition, sorption isotherms for white chocolates were obtained using dynamic vapour sorption at different temperatures. The sorption isotherms showed the presence of amorphous lactose in all the chocolates that were manufactured from milk powders. Moisture that is released during the crystallization of amorphous lactose causes stickiness and agglomeration of the neighbouring particles and starts the thickening process. This process is highly temperature-dependent. On elevating the temperature the lactose crystallization occurs at lower relative humidities. In order to reduce the tendency of white chocolate to thicken, a high free-fat level should be maintained, based on a high total fat content and on the use of high free-fat milk powders, preferably roller-dried whole milk powders or the combination of skimmed milk powder and anhydrous milk fat. 相似文献
79.
《分离科学与技术》2012,47(3):301-302
Abstract Very high rates have been reported for the permeation of acetylene through silicone rubber. Measurements in this laboratory, while consistent with the reported data for the permeation of other gases through silicone rubber, do not confirm the rates reported for acetylene. 相似文献
80.
Y. J. Wu F. Díaz Alvarado J. C. Santos F. Gracia A. F. Cunha A. E. Rodrigues 《化学工程与技术》2012,35(5):847-858
A thermodynamic analysis is performed with a Gibbs free energy minimization method to compare the conventional steam reforming of ethanol (SRE) process and sorption‐enhanced SRE (SE‐SRE) with three different sorbents, namely, CaO, Li2ZrO3, and hydrotalcite‐like compounds (HTlc). As a result, the use of a CO2 adsorbent can enhance the hydrogen yield and provide a lower CO content in the product gas at the same time. The best performance of SE‐SRE is found to be at 500 °C with an HTlc sorbent. Nearly 6 moles hydrogen per mole ethanol can be produced, when the CO content in the vent stream is less than 10 ppm, so that the hydrogen produced via SE‐SRE with HTlc sorbents can be directly used for fuel cells. Higher pressures do not favor the overall SE‐SRE process due to lower yielding of hydrogen, although CO2 adsorption is enhanced. 相似文献