首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   302054篇
  免费   25381篇
  国内免费   16073篇
电工技术   37790篇
技术理论   31篇
综合类   33050篇
化学工业   24844篇
金属工艺   8980篇
机械仪表   20088篇
建筑科学   30675篇
矿业工程   14435篇
能源动力   12898篇
轻工业   9628篇
水利工程   23543篇
石油天然气   14089篇
武器工业   4018篇
无线电   23861篇
一般工业技术   15076篇
冶金工业   10116篇
原子能技术   3284篇
自动化技术   57102篇
  2024年   363篇
  2023年   2849篇
  2022年   5503篇
  2021年   7110篇
  2020年   7779篇
  2019年   5746篇
  2018年   5171篇
  2017年   7151篇
  2016年   8254篇
  2015年   9443篇
  2014年   18765篇
  2013年   16680篇
  2012年   22685篇
  2011年   23670篇
  2010年   17799篇
  2009年   18080篇
  2008年   18005篇
  2007年   23251篇
  2006年   21009篇
  2005年   19030篇
  2004年   15382篇
  2003年   13918篇
  2002年   10912篇
  2001年   9057篇
  2000年   7374篇
  1999年   5838篇
  1998年   4338篇
  1997年   3490篇
  1996年   3022篇
  1995年   2658篇
  1994年   2144篇
  1993年   1490篇
  1992年   1241篇
  1991年   914篇
  1990年   715篇
  1989年   623篇
  1988年   434篇
  1987年   305篇
  1986年   209篇
  1985年   223篇
  1984年   192篇
  1983年   148篇
  1982年   98篇
  1981年   73篇
  1980年   67篇
  1979年   63篇
  1978年   38篇
  1977年   34篇
  1976年   28篇
  1959年   21篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
倪泰乐  冉然  祁娜  赵丽  陈彧 《包装工程》2022,43(22):125-133
目的 将数字化服务融入老年患者就诊流程,建立适老化就诊等待服务系统,在APP开发设计研究中实现软件流程优化。方法 依据ERG理论对老年患者在就诊等待过程中的需求点进行分类整理和层次划分。调研目标用户将分析结果融入服务设计理论,为指导软件开发所涉及的医院就诊流程、用户需求痛点,提出系统性的解决策略。基于交互设计原则展开APP界面设计。结论 构建了以老年患者为中心的就诊等待服务系统,帮助提升其等待过程中的自我效能。完善了基于产品使用方式层级的适老化就诊等待服务APP设计策略,为适老化、数字化产品研发提供了新思路;最终产出APP设计实例,提高了老年群体社会参与度,鼓励老年患者自主就诊,帮助其更加轻松地享受信息化时代带来的红利。  相似文献   
2.
《工程爆破》2022,(4):78-84
介绍了在包头市某工程实施管道穿越黄河施工中,采用爆破法处理卡钻的经验。针对深水环境条件及钻杆内径小不宜采用集团装药的条件,确定采用"小直径爆破筒,钻杆内部装药"的爆破方案,阐述了爆破设计及施工注意事项。可供类似工程参考。  相似文献   
3.
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   
4.
The development of cost-effective bifunctional catalysts with excellent performance and good stability is of great significance for overall water splitting. In this work, NiFe layered double hydroxides (LDHs) nanosheets are prepared on nickel foam by hydrothermal method, and then Ni2P(O)–Fe2P(O)/CeOx nanosheets are in situ synthesized by electrodeposition and phosphating on NiFe LDHs. The obtained self-supporting Ni2P(O)–Fe2P(O)/CeOx exhibit excellent catalytic performances in alkaline solution due to more active sites and fast electron transport. When the current density is 10 mA cm?2, the overpotential of hydrogen evolution reaction and oxygen evolution reaction are 75 mV and 268 mV, respectively. In addition, driven by two Ni2P(O)–Fe2P(O)/CeOx electrodes, the alkaline battery can reach 1.45 V at 10 mA cm?2.  相似文献   
5.
Constructing efficient and stable bifunctional electrocatalysts for overall water splitting remains a challenge because of the sluggish reaction kinetics. Herein, the core-shell hybrids composed of Co(PO3)2 nanorod core and NiFe alloy shell in situ grown on nickel foam (NiFe/Co(PO3)2@NF) are synthesized. Owing to the hierarchical palm-leaf-like structures and strong adhesion between NiFe alloys, Co(PO3)2 and substrates, the catalyst provides a large surface area and rapid charge transfer, which facilitates active sites exposure and conductivity enhancement. The interfacial effect in the NiFe/Co(PO3)2 core-shell structure modulates the electronic structure of the active sites around the boundary, thereby boosting the intrinsic activity. Benefiting from the stable structure, the durability of the catalyst is not impaired by the inevitable surface reconfiguration. The NiFe/Co(PO3)2@NF electrode presents a low cell voltage of 1.63 V to achieve 10 mA cm?2 and manifests durability for up to 36 h at different current densities.  相似文献   
6.
To improve the safety of wet dust removal systems for processing magnesium-based alloys, a new method is proposed for preventing hydrogen generation. In this paper, hydrogen generation by Mg–Zn alloy dust was inhibited with six common metal corrosion inhibitors. The results showed that sodium dodecylbenzene sulfonate was the best hydrogen inhibitor, while CeCl3 enhanced hydrogen precipitation. The film-forming stability of sodium dodecylbenzene sulfonate was tested with different contents, temperatures, Cl? concentrations and perturbation rates. The results showed that this inhibitor formed stable protective films on the surfaces of Mg–Zn alloy particles, and adsorption followed the Langmuir adsorption model.  相似文献   
7.
A dual-coolant integrated experimental facility named DRAGON-V has been developed at the Institute of Nuclear Energy Safety Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, for the key technology research and performance evaluation of candidate liquid lithium-lead (PbLi) blanket of hydrogen fusion reactors. The loop is composed of a material test sub-loop and thermal-hydraulic test sub-loop, the design parameters are PbLi inventory 20 tons, PbLi temperature up to 550 °C, the maximum PbLi flow rate up to 40 kg/s. A novel cold trap system is designed to remove the suspended and crystalized impurities in PbLi fluid with three cooling zones and cross row arrangement of rod bundle filter elements. The paper describes the loop itself and its major components, initial loop testing, flow and measurement diagnostics and current experiments. The obtained test results of the loop and its components have demonstrated that the new facility is fully functioning and ready for experimental studies of material corrosion with/without a magnetic field, magnetohydrodynamic (MHD) effect, purification, heat and mass transfer phenomena in PbLi flows and can also be used in mock-up testing in conditions relevant to fusion applications.  相似文献   
8.
对浸矿后离子型稀土原地浸矿场采用清水进行淋洗,在184天的清水淋洗过程中,尾水氨氮值从最开始的507mg/L,降低至140mg/L,淋洗尾水pH4.52~3.10。淋洗尾水采用两级反渗透膜分离,既回收有价资源稀土,又能使出水氨氮达标。结果表明,产水氨氮浓度稳定低于15mg/L,对稀土的截留率高于98.25%,浓水中稀土离子平均浓度313.4mg/L,可进一步回收稀土资源。  相似文献   
9.
In the present work, the heating performance of a new system combined with a new modified baseboard radiator and fan coil is investigated. Using longitudinal fins with special geometry and also forced airflow at the end of the system causes that at the lower inlet water temperature compared with the conventional models, higher heat output rate be obtained. The heat output rate of the new modified system is obtained by experimental metrology based on the European Standard No. EN-442. Temperature and velocity distribution in the room space is done by simulation of the modified system in the Flovent software. Computational fluid dynamics (CFD) results are validated against experimental results and there is a good agreement between them. Also, the energy consumption of the system during the winter season is calculated in TRANSYS software. Experimental results show that the heat output rate of a new modified heating system with inlet water temperature in the range of 45–55°C is on average 4.17 times higher compared with the conventional model. CFD simulation also showed that the combined system provides good thermal comfort conditions. Energy consumption of the new system reduced about 13% compared with conventional models.  相似文献   
10.
电力保护装置在出厂前要进行严格的板卡测试,传统板卡测试系统自动化程度较低,功能不够强大,且开发成本高,通用性不好。针对以上不足,设计了一种基于虚拟仪器的板卡测试系统,该系统主要由测试程序和上位机两部分组成,测试程序主要完成对板卡设备的模块化测试,并给出测试结果;上位机通过以太网与测试板卡通信,借助FTP和telnet技术,完成整个测试程序的发送、执行、测试结果的获取等功能。以电力保护装置内的CPU板卡为研究对象,结果表明,该测试系统可对板卡进行高效率自动测试,测试结果可靠,故障信息可追踪,可有效提高电力保护装置调试的通过率,保证企业产品的可靠性。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号