全文获取类型
收费全文 | 107165篇 |
免费 | 12757篇 |
国内免费 | 7309篇 |
专业分类
电工技术 | 14770篇 |
技术理论 | 15篇 |
综合类 | 11653篇 |
化学工业 | 9933篇 |
金属工艺 | 3293篇 |
机械仪表 | 5533篇 |
建筑科学 | 12403篇 |
矿业工程 | 2735篇 |
能源动力 | 13112篇 |
轻工业 | 4264篇 |
水利工程 | 2382篇 |
石油天然气 | 2926篇 |
武器工业 | 1079篇 |
无线电 | 9954篇 |
一般工业技术 | 10751篇 |
冶金工业 | 4232篇 |
原子能技术 | 1703篇 |
自动化技术 | 16493篇 |
出版年
2024年 | 244篇 |
2023年 | 2050篇 |
2022年 | 3277篇 |
2021年 | 3752篇 |
2020年 | 3988篇 |
2019年 | 3602篇 |
2018年 | 3185篇 |
2017年 | 3788篇 |
2016年 | 4243篇 |
2015年 | 4265篇 |
2014年 | 6940篇 |
2013年 | 6938篇 |
2012年 | 7824篇 |
2011年 | 8654篇 |
2010年 | 6734篇 |
2009年 | 6951篇 |
2008年 | 6611篇 |
2007年 | 7377篇 |
2006年 | 6108篇 |
2005年 | 5021篇 |
2004年 | 4180篇 |
2003年 | 3516篇 |
2002年 | 3020篇 |
2001年 | 2567篇 |
2000年 | 2162篇 |
1999年 | 1726篇 |
1998年 | 1382篇 |
1997年 | 1132篇 |
1996年 | 1059篇 |
1995年 | 883篇 |
1994年 | 772篇 |
1993年 | 587篇 |
1992年 | 481篇 |
1991年 | 421篇 |
1990年 | 366篇 |
1989年 | 312篇 |
1988年 | 229篇 |
1987年 | 151篇 |
1986年 | 95篇 |
1985年 | 128篇 |
1984年 | 108篇 |
1983年 | 81篇 |
1982年 | 92篇 |
1981年 | 44篇 |
1980年 | 54篇 |
1979年 | 34篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 9篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
31.
32.
33.
《International Journal of Hydrogen Energy》2022,47(62):26435-26457
In this study, some locations with different climates, off-grid zero energy buildings with hydrogen energy storage systems are designed, and transient analysis is conducted. These considered buildings supply their electricity consumption without using the electrical grid and PV panels or wind turbines. Also, they supply thermal comfort to occupants by using a vapor compression chiller and humidifier. Domestic hot water of occupants is supplied using solar collectors. For analyzing building's performance and objectives achievement, TRNSYS software is used. Also, for evaluating occupant thermal comfort, the Fanger model is used. The considered building is a one-story building with a 150 m2 area. Four occupants are considered. Both of them are seated at rest, and another is seated with light working such as typing. Using the Fanger model equation and MATLAB software, the thermal comfort of occupants is determined. For domestic hot water consumption, verified profiles that vary during 24 h of the day are considered. Achieved results show that for humid and cold cities, PV panels with an area of 73 and 76 m2 can be supplied the required electricity of considered building with four occupants and battery state of charge is higher than 50% and 10%, respectively. Moreover, with a suitable air conditioner system, the predicted percentage of dissatisfied (PPD) can be lower than 12% and 8% for humid and cold cities. Therefore, the building can be converted to a zero-energy building using its rooftop area. 相似文献
34.
《International Journal of Hydrogen Energy》2022,47(27):13199-13212
Diesel engine power plants are still widely used on many remote islands in South Korea, despite their disadvantages. Aiming to solve economic and environmental pollution problems, a remote island case study was conducted on Ui Island, aiming to offer a zero-emissions solution by using renewable energy sources in an off-grid application. Power was generated from solar, wind, and hydrogen sources. Li-ion batteries and hydrogen were used as energy storage systems. In addition, PV/battery, wind/battery, PV/wind/battery, PV/battery/PEMFC, wind/battery/PEMFC, and PV/wind/battery/PEMFC systems were simulated using the HOMER software to determine the optimal sizes and techno-economic feasibility. The results show that the PV/wind/battery/PEMFC system is the best system. The configuration of the system consists of 990-kW PV panels, 700-kW wind turbines, a 1088-kWh Li-ion battery bank, 534-kW converter, 300-kW PEMWE system, 300-kg hydrogen tank, and 100-kW PEMFC system. The total NPC of the system is $5,276,069, and the LCOE is 0.366 $/kWh. 相似文献
35.
《Advanced Powder Technology》2022,33(3):103450
In the present investigation, systematic grinding experiments were conducted in a laboratory ball mill to determine the breakage properties of low-grade PGE bearing chromite ore. The population balance modeling technique was used to study the breakage parameters such as primary breakage distribution (Bi, j) and the specific rates of breakage (Si). The breakage and selection function values were determined for six feed sizes. The results stated that the breakage follows the first-order grinding kinetics for all the feed sizes. It was observed that the coarser feed sizes exhibit higher selection function values than the finer feed size. Further, an artificial neural network was used to predict breakage characteristics of low-grade PGE bearing chromite ore. The predicted results obtained from the neural network modeling were close to the experimental results with a correlation of determination R2 = 0.99 for both product size and selection function. 相似文献
36.
《International Journal of Hydrogen Energy》2022,47(58):24569-24583
Hydrogen generation from renewable energy resources is considered as a suitable solution to solve the problems related to the energy sector and the reduction of greenhouse gases. The aim of this study is to provide an integrated framework for identifying suitable areas for the construction of wind farms to produce hydrogen. For this purpose, a combined method of Geographic Information System (GIS) and multi-criteria decision making (MCDM) has been used to locate the power plant in Yazd province. The GIS method in the present study consisted of two parts: constraints and criteria. The constraint section included areas that were unsuitable for the construction of wind farms to produce power and hydrogen. In the present study, various aspects such as physical, economic and environmental had been considered as constraints. In the criteria section, eight different criteria from technical aspects (including average wind speed, hydrogen production potential, land slope) and economic aspects (including distance to electricity grid, distance to urban areas, distance to road, distance to railway and distance to centers of High hydrogen consumption) had been investigated. The MCDM tool had been used to weigh the criteria and identify suitable areas. Analytic Hierarchy Process (AHP) technique was used for weighting the criteria. The results of AHP weighting method showed that economic criteria had the highest importance with a value of 0.681. The most significant sub-criterion was the distance to urban areas and the least significant sub-criterion was the distance to power transmission lines. The results of GIS-MCDM analysis had shown that the most proper areas were in the southern and central sectors of Yazd province. In addition, the feasibility of hydrogen production from wind energy had shown that this province had the capacity to generate hydrogen at the rate of 53.6–128.6 tons per year. 相似文献
37.
《International Journal of Hydrogen Energy》2022,47(48):20705-20717
Water electrolysis technologies aim to provide a significant increase in green hydrogen production efficiency. In this work, a framework was developed to explore the use of supercritical water for alkaline electrolysis. This framework was used to perform Arrhenius analysis as a function of potential, and to explore activation energies for sub- and supercritical water electrolysis. An analysis of the conductivity of solution unveiled a discontinuity in the trends between sub- and supercritical potassium hydroxide solution conductivity. Unlike prior work on supercritical water electrolysis, this work investigates trends in electrochemical parameters, the sources of these trends, and how they change between the sub- and supercritical regimes. 相似文献
38.
《International Journal of Hydrogen Energy》2022,47(94):39864-39874
The reaction of H2 and O2 to water are studied over a Ag–Pd/TiO2 anatase catalyst, under dark and photo-irradiation conditions in the gas and liquid phases. The catalyst consisted of metal particles of mean size of ca.1 nm dispersed over 10–15 nm TiO2 particles. Kinetic parameters including order of reaction (n), rate constant (k), and activation energy (Ea), were evaluated. Ea for the thermal reaction was found to be 49-47 kJ mol?1. The oxidation reaction rate constant was found to be ca. 3 times higher in the presence of photons when compared to dark reaction at room temperature. The overall quantum yield of the reaction in the slurry phase was found to be 0.09. Considering the number of metal particles on TiO2, the photon yield per metal particle was found to be 0.16. A possible explanation of the changes in kinetics with respect to experimental conditions is given. 相似文献
39.
Adebowale Martins Obalalu Lawal Lanre Adebayo Ilhami Colak Adebayo Olusegun Ajala Fatai Adisa Wahaab 《亚洲传热研究》2022,51(5):3951-3978
Minimizing entropy generation is a technique that helps improve the effectiveness of real processes by studying the associated irreversibility of system performance of nanofluid. This study examines the entropy generation analysis of electromagnetohydrodynamic radiative Casson flow induced by a stretching Riga plate in a non-Darcian porous medium under the influence of internal energy change, Arrhenius activation energy, chemical reaction, and melting heat transfer. The thermophysical features of the fluid are assumed constant in most of the literature. However, this current research bridges this gap by considering viscosity, conductivity, and diffusivity as temperature-dependent variables. Also, the exponential decaying Grinberg term is used as a resistive force in this investigation due to the electromagnetic properties of the Riga plate in the momentum conservation equation. Some suitable dimensionless variables are introduced to remodel the transport equations into unitless ones and then solved numerically by employing Galerkin Weighted Residual Method. Analyses reveal that the Casson parameter declines the fluid velocity, while the existence of the melting parameter has the opposite effect. Also, this article includes some future recommendations. 相似文献
40.
乡村产业中的化石能源设备逐渐被电能技术替代,引起了乡村负荷波动增大、部分时段产生集中高负荷的问题。为了解决以上问题,将低品位清洁能源应用至乡村的茶叶生产中,针对烘茶全过程的工艺要求提出了跨临界CO2热泵烘茶技术;并以某茶叶生产乡村为对象,对其代表台区的全年日用电量及产茶日负荷进行了分析,得出采用CO2热泵烘茶后其负荷得到大幅度削减,整体可降低至原负荷的39.6%~46.8%,峰值负荷与平时负荷的比值由原本的13.6降至5.4~6.2。跨临界CO2热泵应用至农产品生产中可有效缓解乡村供电压力。 相似文献