全文获取类型
收费全文 | 1775篇 |
免费 | 17篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 28篇 |
综合类 | 35篇 |
化学工业 | 408篇 |
金属工艺 | 178篇 |
机械仪表 | 248篇 |
建筑科学 | 161篇 |
矿业工程 | 20篇 |
能源动力 | 208篇 |
轻工业 | 42篇 |
水利工程 | 9篇 |
石油天然气 | 22篇 |
武器工业 | 5篇 |
无线电 | 64篇 |
一般工业技术 | 288篇 |
冶金工业 | 50篇 |
原子能技术 | 11篇 |
自动化技术 | 34篇 |
出版年
2023年 | 38篇 |
2022年 | 54篇 |
2021年 | 52篇 |
2020年 | 45篇 |
2019年 | 42篇 |
2018年 | 27篇 |
2017年 | 33篇 |
2016年 | 27篇 |
2015年 | 38篇 |
2014年 | 83篇 |
2013年 | 113篇 |
2012年 | 95篇 |
2011年 | 155篇 |
2010年 | 118篇 |
2009年 | 115篇 |
2008年 | 75篇 |
2007年 | 115篇 |
2006年 | 96篇 |
2005年 | 101篇 |
2004年 | 55篇 |
2003年 | 54篇 |
2002年 | 46篇 |
2001年 | 39篇 |
2000年 | 30篇 |
1999年 | 40篇 |
1998年 | 29篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有1811条查询结果,搜索用时 15 毫秒
51.
Hossein Vojoudi Jahan B. Ghasemi Ahmadreza Hajihosseinloo Bahareh Bastan Alireza Badiei 《Advanced Powder Technology》2021,32(4):1060-1069
A hybrid nanocomposite of alumina and hematite was synthesized by ultrasonic spray pyrolysis technique. The study of microscopic images, mapping analysis, and XRD patterns revealed that the Al2O3 – Fe2O3 nanocomposite was composed of separated spherical particles with a thin layer ball-shaped structure that metal oxides are uniformly distributed in the wall of hollow sphere particles, led to a coherent and monotonous construction. A series of coefficients of equilibrium sorption of polycyclic aromatic hydrocarbons (PAHs) as hazardous materials were measured on the prepared composite material in a batch technique. The free or pure Al2O3 or Fe2O3 showed negligible removal efficiency for the mentioned analytes. The various significant variables, such as initial analyte concentration, solution pH, adsorbent dose, and contact time to remove analyte, were studied in the aqueous solutions. Adsorption data were modeled to Langmuir, Freundlich, and Temkin isotherms, and a good correlation found in the case of Langmuir isotherm and adsorption capacity for anthracene, phenanthrene, and naphthalene were 370, 333, and 322 mg g?1, respectively. Investigation of the kinetic models proved a pseudo-second-order, and the prepared adsorbent can be reused more than 7 times without a significant decrease of adsorption performance. 相似文献
52.
《Measurement》2016
Blade is one of the most important parts in turbine machinery. The complex geometry of blades not only makes them difficult to fabricate, but also leads them difficult to inspect. Typically, the surface of blades is measured by using coordinate measuring machine (CMM). Since the measurement time and cost increase proportionally as the increase of measurement points, it is essential to sample measurement points which can represent entire blade with sufficient confidence and accuracy. In order to achieve a certain allowable deviation with a suitable set of points, a practical sampling method for surface measurement of blades was studied. Firstly, the leading edge curve and trailing edge curve were supposed to represent the twisted and bend information of blades. A sampling method based on maximum chordal deviation for leading edge curve and trailing edge curve was researched. Further, a fusion approach for sampling points on both edge curves, which determine the cross-sections, was proposed. Secondly, the inspection points sampling method for sectional curves were investigated. Finally, two simulation and one experimental examples were used to demonstrate the sampling methodology. The results indicated that the approach of this study can ensure the measurement precision at high curvature potion by measuring a small number of points. 相似文献
53.
For a better design of tidal stream turbines operated in off-design conditions, analyses considering the effects of blade deformation and yawed inflow conditions are necessary. The flow load causes deformation of the blade, and the deformation affects the turbine performance in return. Also, a yawed inflow influences the performance of the turbine. As a validation study, a computational fluid dynamics (CFD) simulation was carried out to predict the performance of a horizontal axis tidal stream turbine (HATST) with rigid blades. The numerical uncertainty for the turbine performance with blade deformation and a yawed inflow was evaluated using the concept of the grid convergence index (GCI). A fluid–structure interaction (FSI) analysis was carried out to estimate the performance of a turbine with flexible composite blades, with the results then compared to those of an analysis with rigid blades. The influence of yawed inflow conditions on the turbine performance was investigated and found to be important in relation to power predictions in the design stages. 相似文献
54.
The effects of blade tenderization (BT), two aging methods (dry (D) and wet (W)), and aging time (2 and 23 d) on tenderness, color, and sensory properties of Longissimus lumborum muscles from 12 cull Holstein cows were evaluated. Dry-aged loins had higher combined trim and aging losses than control (C) for both D- and W-aging, mostly because of excess trim losses. BT steaks had WBSF of 33.13 N while C steaks had WBSF of 41.46 N (P = 0.09). Aging decreased WBSF. Blade tenderized steaks had higher cook loss than C steaks. Aging, W-aging, and BT × W-aging improved myofibrillar (sensory) tenderness scores. Aging and/or BT improves sensory panel tenderness cull cow Longissimus lumborum steaks. Aging and blade tenderization combined can increase tenderness and value of Longissimus steaks from cull Holstein cows. 相似文献
55.
María Alba Pilar Formentín Josep Ferré-Borrull Josep Pallarès Lluís F Marsal 《Nanoscale research letters》2014,9(1):411
We report on the fabrication of polyelectrolyte multilayer-coated hollow silicon dioxide micropillars as pH-responsive drug delivery systems. Silicon dioxide micropillars are based on macroporous silicon formed by electrochemical etching. Due to their hollow core capable of being loaded with chemically active agents, silicon dioxide micropillars provide additional function such as drug delivery system. The polyelectrolyte multilayer was assembled by the layer-by-layer technique based on the alternative deposition of cationic and anionic polyelectrolytes. The polyelectrolyte pair poly(allylamine hydrochloride) and sodium poly(styrene sulfonate) exhibited pH-responsive properties for the loading and release of a positively charged drug doxorubicin. The drug release rate was observed to be higher at pH 5.2 compared to that at pH 7.4. Furthermore, we assessed the effect of the number of polyelectrolyte bilayers on the drug release loading and release rate. Thus, this hybrid composite could be potentially applicable as a pH-controlled system for localized drug release. 相似文献
56.
The research work aims at investigating the fitness of jute and hollow conjugated polyester (HCP) composites for indoor and outdoor applications. Limiting oxygen value index, natural weathering exposure was done on four optimized composite structures; i) sandwich structure composite (A); ii) blended non-woven structure composite (B); iii) multiple layers with 5% of low melt polyester added composite (C); (iv) multiple layers of non-woven stitched composite (D) were produced. Their tensile strength, strain at break, and Young’s modulus values were evaluated both before and after the coating of acrylic-based silicon emulsion (ASE). From the experimental results, it is suggested that sample A can be used for an interior trim, sample B can be a base material for interior designing, sample C can replace the usage of wood, plastics, metals, and alloys in hardware applicationsand sample D can be used in interiors as an insulation material in commercial buildings for the purpose of internal cooling or heating. 相似文献
57.
58.
《Advanced Powder Technology》2020,31(12):4642-4647
Hollow γ-MnO2 sphere was obtained by annealing the precursor at 400 °C with different holding time. The influences of different holding time on the morphology and crystalline structure of final products have been discussed in detail, and the microwave absorption properties of the as-products were also investigated. The results exhibited that finer crystalline feature of the γ-MnO2 and larger pore size in the hollow γ-MnO2 sphere could be obtained with the extended holding time. The MnO2/paraffin composites (50 wt% loading) present extraordinary microwave absorption performance, and the minimum reflection loss (RL) values is −51.3 dB at 4.9 GHz with the thickness of 3.5 mm. The excellent electromagnetic absorption properties can be ascribed to the hollow structure, perfect impedance matching behavior and the multiple interface polarization effect. 相似文献
59.
Water and waste-water treatment through the use of the membrane filtration technology is one of the processes utilized currently to meet the growing demand for water. While new technologies can harness water from various non-traditional sources such as oceans, there remains the possibility of making drinking water more expensive through the use of costly water treatment equipment. To prevent this and ensuing catastrophes in the world, the water industry needs a strategy that keeps the price of water and price of products aiding the treatment of water controlled in to the future. 相似文献
60.
《International Journal of Hydrogen Energy》2014,39(36):21053-21059
Sulfur-free hydrogen production is significant for sustainable energy such as fuel cell to avoid poisoning catalysts. The hollow fiber membrane is proposed as sulfur trapper for the hydrocarbon fuels. Hollow fiber membranes with polyimide (PI) matrix and adsorptive zeolites fillers are fabricated by dry–wet spinning with subsequent imidization process. By detailed investigation of FT-IR, thermal degradation cures, morphology and sulfur trapping performance, the molecular structure, thermostability and adsorption channels of membranes have been analyzed. The hollow fiber membranes have abundant pores, and the zeolites particles are incorporated in the three-dimension polymer matrix. The inlet fuel can be desulfurized to below 0.1 mg L−1, which means that the outlet fuel can be used as sulfur-free hydrogen source for fuel cell applications. Excellent sustainability of the system with hollow fiber configuration show attractive on-board application potential. 相似文献