全文获取类型
收费全文 | 18391篇 |
免费 | 1061篇 |
国内免费 | 454篇 |
专业分类
电工技术 | 3960篇 |
综合类 | 1001篇 |
化学工业 | 3768篇 |
金属工艺 | 294篇 |
机械仪表 | 474篇 |
建筑科学 | 1880篇 |
矿业工程 | 550篇 |
能源动力 | 1344篇 |
轻工业 | 1319篇 |
水利工程 | 986篇 |
石油天然气 | 592篇 |
武器工业 | 19篇 |
无线电 | 196篇 |
一般工业技术 | 1142篇 |
冶金工业 | 513篇 |
原子能技术 | 953篇 |
自动化技术 | 915篇 |
出版年
2024年 | 39篇 |
2023年 | 169篇 |
2022年 | 363篇 |
2021年 | 522篇 |
2020年 | 492篇 |
2019年 | 355篇 |
2018年 | 307篇 |
2017年 | 421篇 |
2016年 | 447篇 |
2015年 | 496篇 |
2014年 | 1284篇 |
2013年 | 1019篇 |
2012年 | 1413篇 |
2011年 | 1461篇 |
2010年 | 1181篇 |
2009年 | 1018篇 |
2008年 | 880篇 |
2007年 | 1138篇 |
2006年 | 1180篇 |
2005年 | 981篇 |
2004年 | 813篇 |
2003年 | 811篇 |
2002年 | 658篇 |
2001年 | 503篇 |
2000年 | 408篇 |
1999年 | 311篇 |
1998年 | 196篇 |
1997年 | 180篇 |
1996年 | 146篇 |
1995年 | 145篇 |
1994年 | 114篇 |
1993年 | 73篇 |
1992年 | 69篇 |
1991年 | 49篇 |
1990年 | 46篇 |
1989年 | 45篇 |
1988年 | 27篇 |
1987年 | 30篇 |
1986年 | 23篇 |
1985年 | 22篇 |
1984年 | 22篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1965年 | 1篇 |
1959年 | 5篇 |
1954年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
31.
《International Journal of Hydrogen Energy》2021,46(64):32350-32357
Currently, the United Energy System (UEC) of Russia is trending in the deficit of peak and half-peak capacity with a simultaneous increase in the number of nuclear power plants (NPPs), which will require the participation of the NPPs in the variable part of the schedule of electrical loads.In addition to the economic need to maintain the high-level utilization rate, there are technological limitations of maneuverability for NPPs.The authors developed an approach to solving this problem by combining with an environmentally friendly energy source – an autonomous hydrogen power complex, which includes thermal batteries and an additional multifunctional low-power steam turbine installation.The developed energy complex can also provide reliable reservation of electricity supply to consumers of their own needs of the nuclear power plant in case of complete blackout of the plant.The feasibility study of the main equipment of the autonomous hydrogen power complex, which is necessary for combining with a two-unit nuclear power plant with WWER-1000, has been evaluated.On the basis of the assessment of the inflation indicators of the Russian economy over the past 11 years, three variants of fuel cost dynamics and tariff rates for electricity (capacity) as well as the size of operating costs, including depreciation deductions to the main equipment, are defined, taking into account the current principles of price formation.The result is a value for accumulated net present value, depending on the ratio of the cost of the half-peak and off-peak electricity at different inflation rates.The positive economic effect of reducing the risk of the core damage accident, replacing the construction of the gas turbine unit as a maneuverable source of electricity in the power grid and increasing the income of the Russian federal budget from the savings of natural gas has been taken into account.The greatest economic efficiency is achieved with maximum projected inflation, which is associated with the maximum rate of discounting and the high rate of growth of electricity tariffs.Reducing the risk of the core damage accident ensures that the proposed approach is competitive in all the inflation options under consideration and the ratio of electricity tariffs. 相似文献
32.
某F级燃气电厂运行中发现NOx数值存在较大波动,通过分析和排查,发现烟气分析仪存在老化现象,同时CEMS仪表间存在布置不合理情况,通过处理NOx数值波动得以有效改善,可为同类电厂烟气系统数据异常处理提供参考。 相似文献
33.
Hydrodistillation condition adjustment for different material particle sizes: a method to increase batch‐to‐batch quality consistency 下载免费PDF全文
Danni Wei Guilin Cheng Kaiyi Huang Jinyang Fang Binjun Yan 《International Journal of Food Science & Technology》2018,53(5):1140-1148
Varying material particle sizes represent a common contributing factor to the batch‐to‐batch variation of extraction yields. To increase the batch‐to‐batch quality consistency of extracts, a method was proposed to adjust the extraction conditions for different material particle sizes, taking the hydrodistillation extraction process of Radix Curcumae and Fructus Gardeniae as a case study. Statistical models were built for five sesquiterpenes including curcumenone, curcumenol, curdione, curzerenone and furanodienone, to quantitatively describe the effects of particle size and process parameters on their extraction yields. An increase in sodium chloride concentration remarkably increased the yields of curcumenone and curcumenol, and a larger solvent‐to‐solid ratio increased the yields of five sesquiterpenes. Under the adjusted process parameters for two different particle sizes, the yield for each compound was controlled to fall in the 90–110% target range. The proposed method can be applied to various extraction processes of foods and herbal medicines. 相似文献
34.
Ergonomic interventions may potentially reduce MSDs, but the context of industries (barriers, ever-changing situations, dialogue processes) might play a significant role in the success of interventions. This study evaluates the effectiveness of ergonomic interventions including engineering/technical and organizational interventions, and the involvement of the stakeholders in reducing musculoskeletal risk factors/symptoms. A pre-post-test experimental study in non-randomized groups was performed over three years in a sector of a truck assembly plant. The mean age of the operators in the sector for the initial and second assessment time was 42.0 (±7.6) years and 39.0 (±8.7), respectively. The mean length of work experience in the current job was 15.2 (±7.2) years and 13.9 (±7.3) for the initial and second assessment times, respectively. Five engineering ergonomic solutions and organizational interventions were implemented after a comprehensive ergonomic analysis. The organizational interventions consisted mostly of transferring and redistributing the tasks, i.e., ergonomically balancing and redesigning of the workstations. Before performing the interventions, the findings of the ergonomic study were presented at several meetings to encourage the involvement of the stakeholders (including managers, engineers, and operators) in the interventions. This study showed that a combination of ergonomic measures—engineering and organizational interventions—could reduce physical workloads. Musculoskeletal symptoms decreased after interventions although the difference was not significant. 相似文献
35.
36.
Inspired by the impulsive movements in plants, this research investigates the physics of a novel fluidic origami concept for its pressure-dependent multi-stability. In this innovation, fluid-filled tubular cells are synthesized by integrating different Miura-Ori sheets into a three-dimensional topological system, where the internal pressures are strategically controlled similar to the motor cells in plants. Fluidic origami incorporates two crucial physiological features observed in nature: one is distributed, pressurized cellular organization, and the other is embedded multi-stability. For a single fluidic origami cell, two stable folding configurations can coexist due to the nonlinear relationships among folding, crease material deformation and internal volume change. When multiple origami cells are integrated, additional multi-stability characteristics could occur via the interactions between pressurized cells. Changes in the fluid pressure can tailor the existence and shapes of these stable folding configurations. As a result, fluidic origami can switch between being mono-stable, bistable and multi-stable with pressure control, and provide a rapid ‘snap-through’ type of shape change based on the similar principles as in plants. The outcomes of this research could lead to the development of new adaptive materials or structures, and provide insights for future plant physiology studies at the cellular level. 相似文献
37.
We investigated proposed design of a double-flash system and compared it to the existing single-flash power plant in Dieng, Indonesia, which uses waste brine from a high pressure separator. The performance of the double-flash system was evaluated using the second law of thermodynamics, and this was based on energy and exergy analyses. The Engineering Equation Solver (EES) was used to solve the relevant mathematical equations.Our results indicate that the double-flash design is interesting for application in Dieng since the power output would increase by 19.97%. Moreover, the precipitation system to avoid silica deposition in the injection well does not have to change much. Therefore, the building costs associated with the new double-flash system would be minimal. The available exergy from the reservoir is 66,204 kW based on the enthalpy determined by TFT (Tracer Flow Test) measurements. The single-flash power plant has a net power output of 23,400 kW with a second law efficiency of 36.7%. In the double-flash design, components such as a LPS, a second purifier and an HPT would be added to the plant. Furthermore, our calculations indicate that the power plant's output and second law efficiency would increase to 29,155 kW and 44.04%, respectively. The waste brine disposed of using this precipitation system would decrease by 8.22% at 5443 kW. 相似文献
38.
从工程实例出发,文章简单介绍了燃机电厂的管线特点,对厂区管线重点区域的具体布置方法进行了分析,以探讨在管廊通道与节约用地之间作出合理的选择。 相似文献
39.
上海石化0.4 Mt/a PTA装置扩产改造中,TJ-302氧化母液罐处理量不能满足需求,需要大幅度加快循环速度,在原有设备上增设搅拌器是最经济的选择。增设搅拌器后,又出现新问题,由于循环速度加快,设备中原有的固体含量增加,必须进行再改造。经充分的分析研究以及计算,增设了罐内轴滑动轴承,从而解决了上述问题。 相似文献
40.
The aim of this study was to assess the ergonomic physical exposure, organizational and psychosocial factors in a truck assembly plant for two different cycle times (11 min and 8 min). A self-reported questionnaire was applied to evaluate subjective physical exposure, organizational and psychosocial factors by operators in two organization of an assembly process. The initial cycle time was 11 min (system A) and the new was 8 min (system B). The same work and assembly tasks had to be completed in both systems. However, the organization and distribution of the tasks and workstations were reorganized. The results of the questionnaire showed that subjective estimation by the operators regarding ergonomic risk factors was better in the new organization and self-reported WR-MSDs symptoms were fewer. However, exposure to risk factors and WR-MSDs symptoms was not statistically different between two cycle times. The findings provide better understanding of how organizational changes can modify ergonomic exposure in manufacturing assembly industries. Effective interventions are thus not only engineering solutions but also organizational and administrative adaptations. 相似文献