全文获取类型
收费全文 | 13232篇 |
免费 | 1397篇 |
国内免费 | 629篇 |
专业分类
电工技术 | 6135篇 |
综合类 | 931篇 |
化学工业 | 478篇 |
金属工艺 | 279篇 |
机械仪表 | 911篇 |
建筑科学 | 327篇 |
矿业工程 | 263篇 |
能源动力 | 1107篇 |
轻工业 | 136篇 |
水利工程 | 505篇 |
石油天然气 | 331篇 |
武器工业 | 126篇 |
无线电 | 1282篇 |
一般工业技术 | 467篇 |
冶金工业 | 251篇 |
原子能技术 | 527篇 |
自动化技术 | 1202篇 |
出版年
2024年 | 57篇 |
2023年 | 123篇 |
2022年 | 237篇 |
2021年 | 315篇 |
2020年 | 386篇 |
2019年 | 287篇 |
2018年 | 294篇 |
2017年 | 434篇 |
2016年 | 484篇 |
2015年 | 568篇 |
2014年 | 893篇 |
2013年 | 752篇 |
2012年 | 1053篇 |
2011年 | 1112篇 |
2010年 | 829篇 |
2009年 | 811篇 |
2008年 | 835篇 |
2007年 | 976篇 |
2006年 | 821篇 |
2005年 | 692篇 |
2004年 | 582篇 |
2003年 | 501篇 |
2002年 | 428篇 |
2001年 | 377篇 |
2000年 | 329篇 |
1999年 | 245篇 |
1998年 | 151篇 |
1997年 | 130篇 |
1996年 | 98篇 |
1995年 | 102篇 |
1994年 | 67篇 |
1993年 | 57篇 |
1992年 | 56篇 |
1991年 | 29篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1959年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2022,48(8):10852-10861
Carbon cloth was used as a flexible substrate for bismuth telluride (Bi2Te3) particles to provide flexibility and improve the overall thermoelectric performance. Bi2Te3 on carbon cloth (Bi2Te3/CC) was synthesized via a hydrothermal reaction with various reaction times. After over 12 h, the Bi2Te3 particles showed a clear hexagonal shape and were evenly adhered to the carbon cloth. Selenium (Se) atoms were doped into the Bi2Te3 structure to improve its thermoelectric performance. The electrical conductivity increased with increasing Se-dopant content until 40% Se was added. Moreover, the maximum power factor was 1300 μW/mK2 at 473 K for the 30% Se-doped sample. The carbon cloth substrate maintained its electrical resistivity and flexibility after 2000 bending cycles. A flexible thermoelectric generator (TEG) fabricated using the five pairs of 30% Se-doped sample showed an open-circuit voltage of 17.4 mV and maximum power output of 850 nW at temperature difference ΔT = 30 K. This work offers a promising approach for providing flexibility and improving the thermoelectric performance of inorganic thermoelectric materials for wearable device applications using flexible carbon cloth substrate for low temperature range application. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(76):32359-32371
On-site hydrogen production through steam-methane reforming (SMR) from city gas or natural gas is believed to be a cost-effective way for hydrogen-based infrastructure due to high cost of hydrogen transportation. In recent years, there have been a lot of on-site hydrogen fueling stations under design or construction in China. This study introduces current developments and technology prospects of skid-mounted SMR hydrogen generator. Also, technical solutions and economic analysis are discussed based on China's first on-site hydrogen fueling station project in Foshan. The cost of hydrogen product from skid-mounted SMR hydrogen generator is about 23 CNY/kg with 3.24 CNY/Nm3 natural gas. If hydrogen price is 60 CNY/kg, IRR of on-site hydrogen fueling station project reaches to 10.8%. While natural gas price fall to 2.3 CNY/Nm3, the hydrogen cost can be reduced to 18 CNY/kg, and IRR can be raised to 13.1%. The conclusion is that skid-mounted SMR technology has matured and is developing towards more compact and intelligent design, and will be a promising way for hydrogen fueling infrastructures in near future. 相似文献
3.
This paper proposes a method for the coordinated control of power factor by means of a multiagent approach. The proposed multiagent system consists of two types of agent: single feeder agent (F_AG) and bus agent (B_AG). In the proposed system, an F_AG plays as an important role, which decides the power factors of all distributed generators by executing the load flow calculations repeatedly. The voltage control strategies are implemented as the class definition of Java into the system. In order to verify the performance of the proposed method, it has been applied to a typical distribution model system. The simulation results show that the system is able to control very violent fluctuation of the demands and the photovoltaic (PV) generations. 相似文献
4.
This paper presents the stability improvement results of hybrid doubly fed induction generator (DFIG)-based and permanent magnet generator (PMG)-based offshore wind farms (OWFs) using a static synchronous series compensator (SSSC). An adaptive-network-based fuzzy inference system (ANFIS) controller of the proposed SSSC is designed to render adequate damping characteristics to the studied system. A frequency-domain approach based on a linearized system model using eigenvalue technique analysis is performed. A time-domain scheme based on a nonlinear system model subject to a three-phase short circuit fault at infinite bus with variations in the signal transmission delays has also been investigated to compare the damping of the studied system in cases of with and without controller. The simulation results with MATLAB/SIMULINK toolbox have been presented. It can be concluded from the simulation results that the proposed SSSC joined with the designed ANFIS damping controller can offer adequate damping performance to the studied hybrid DFIG-based and PMG-based OWFs under severe disturbance. 相似文献
5.
Design and Fabrication of Concentration‐Gradient Generators with Two and Three Inlets in Microfluidic Chips 下载免费PDF全文
A simple and low‐cost method for designing and fabricating concentration‐gradient generators with two and three inlets is proposed which can generate different concentration gradients at varying flow velocities. The microchannel structure was designed in S‐shape and left‐right symmetry. The concentration‐gradient generator was simulated based on the finite element method. The microchannels were processed on a computer numerical control (CNC) engraving and milling machine on poly(methylmethacrylate) substrate, and then two concentration‐gradient generators were fabricated by hot bonding technology. The results of experiment and simulation were compared to prove the feasibility of the method. Flow velocity was an important factor for generating different concentration gradients. The concentration‐gradient profiles of the generators with two and three inlets present approximately linear and quadratic curves. 相似文献
6.
7.
8.
9.
10.
适用于微机的核蒸汽发生器热工水力分析程序—SGTH—2 总被引:1,自引:0,他引:1
本程序用于计算核蒸汽发生器的热工水力分布参数以及一次侧流动压降、二次侧自然循环和稳态特性,将本程序的计算结果与法国对同型号蒸汽发生器的实测数据以及用 ATHOS 程序的相应计算结果进行比较,表明主要热工水力参数能令人满意地吻合。 相似文献