全文获取类型
收费全文 | 27573篇 |
免费 | 3267篇 |
国内免费 | 1498篇 |
专业分类
电工技术 | 2251篇 |
技术理论 | 5篇 |
综合类 | 2085篇 |
化学工业 | 4398篇 |
金属工艺 | 1301篇 |
机械仪表 | 1513篇 |
建筑科学 | 2435篇 |
矿业工程 | 808篇 |
能源动力 | 768篇 |
轻工业 | 2910篇 |
水利工程 | 561篇 |
石油天然气 | 1321篇 |
武器工业 | 263篇 |
无线电 | 3380篇 |
一般工业技术 | 3203篇 |
冶金工业 | 1009篇 |
原子能技术 | 383篇 |
自动化技术 | 3744篇 |
出版年
2025年 | 8篇 |
2024年 | 641篇 |
2023年 | 713篇 |
2022年 | 1184篇 |
2021年 | 1508篇 |
2020年 | 1218篇 |
2019年 | 979篇 |
2018年 | 985篇 |
2017年 | 1028篇 |
2016年 | 953篇 |
2015年 | 1244篇 |
2014年 | 1542篇 |
2013年 | 1816篇 |
2012年 | 2054篇 |
2011年 | 2106篇 |
2010年 | 1726篇 |
2009年 | 1595篇 |
2008年 | 1523篇 |
2007年 | 1442篇 |
2006年 | 1349篇 |
2005年 | 1072篇 |
2004年 | 706篇 |
2003年 | 595篇 |
2002年 | 536篇 |
2001年 | 507篇 |
2000年 | 546篇 |
1999年 | 482篇 |
1998年 | 393篇 |
1997年 | 337篇 |
1996年 | 318篇 |
1995年 | 226篇 |
1994年 | 235篇 |
1993年 | 157篇 |
1992年 | 144篇 |
1991年 | 106篇 |
1990年 | 79篇 |
1989年 | 77篇 |
1988年 | 40篇 |
1987年 | 38篇 |
1986年 | 36篇 |
1985年 | 19篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 18篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 3篇 |
1966年 | 1篇 |
1959年 | 6篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
101.
快速心肌显像剂^99mTc—TEBO的标记和动物体内分布实验 总被引:2,自引:0,他引:2
报道了用^99mTc标记Teboroxime(简称TEBO),并在标记后对其质量进行了鉴定。结果表明,其物理性质、化学性质及生物学性质均符合国家制定的放射性药物的质量标准;动物实验表明,小鼠注射量为成人用量的100倍、观察15天后,实验组和对照组无差别;注入量为0.1ml(207.2Bq/只),2min后心肌摄取达峰值17.75±0.33%(g organ)^-1;心肌清除也快,15min已清除至 相似文献
102.
从现有水冷反应堆核电厂存在堆芯熔化危险这一安全问题的焦点出发,分析了改进型反应堆AP-600、SIR、非能动安全反应堆PIUS和具有固有安全的模块高温气冷堆MHTGR等的安全特性.按照下一代水冷反应堆的设计要求和用户要求,提出了解决水堆核电厂安全问题的新概念——自安全铀氢锆反应堆,该堆型可能成为世界水堆核电发展的一个方问。中国核动力研究设计院正在探讨这种堆型。 相似文献
103.
监控系统是一种利用计算机软件程序与外接的硬件摄像头进行协作而运行的一种计算机程序。计算机监控系统,应用十分广泛。在人们的生活中,如银行取款处、大型的超市、工业车间以及航天航空等方方面面。其渗透的领域以及范围非常广泛,从生活、工业生产到军事等方面都有着非常优异的表现。文章将主要对计算机监控系统的技术进行分析,探究其在不同应用层面的技术问题。 相似文献
104.
A parametric study of a horizontal rotating fluidized bed using slotted and sintered metal cylindrical gas distributors 总被引:2,自引:0,他引:2
Gui-Hua Qian Istv n B gyi Robert Pfeffer Henry Shaw John G. Stevens 《Powder Technology》1998,100(2-3):190-199
The pressure drop in a horizontal rotating fluidized bed was measured using slotted and sintered metal cylindrical gas distributors as a function of rotating speed, gas velocity and bed thickness. Experiments were conducted using polydisperse alumina particles and nearly monodisperse glass beads. The pressure drop for the slotted distributor exhibited a much larger pressure overshoot at incipient fluidization than the sintered metal distributor. This behavior was also studied using high-resolution photography. Physically consistent explanations are presented for the observed phenomena. The experimental results are compared to theoretical models available in the literature. 相似文献
105.
106.
The phase behavior of polydisperse ABA triblock copolymers is studied using dissipative particle dynamics simulations, focusing on the emergence and property of bicontinuous structures. Bicontinuous structures are characterized by two separate, intermeshed nanoscopic domains extending throughout the material. The connectivity of polymeric bicontinuous structures makes them highly desirable for many applications. For conventional monodisperse diblock and triblock copolymers, regular bicontinuous structures (i.e., gyroid and Fddd) can be formed over a narrow composition window of 3%. We demonstrate that the composition window for the formation of bicontinuous structures can be regulated by designed polydispersity distributions of ABA triblock copolymers. In particular, introducing polydispersity in both A and B blocks can lead to a significant enhancement of the composition window of bicontinuous structures with both continuous A and B domains. The mechanism of the bicontinuous structure enhancement is elucidated from the distribution of the long and short blocks. Furthermore, it is shown that the polymeric bicontinuous structures from polydisperse ABA triblock copolymers possess good continuity throughout the sample, making them ideal candidates for advanced applications. 相似文献
107.
本文结合了先进发达国家的一些技术情况,介绍了多异氰酸酯系列产品在国际市场上的品种和优良性能,总结了它的化学合成的原理,提出了生产设备的设计方案、生产车间的设计方案、生产工艺的流程及要求等,指出了它的系列产品的国产工业化的重要性。 相似文献
108.
Information Systems Frontiers - Ransomware is a self-propagating malware encrypting file systems of the compromised computers to extort victims for financial gains. Hundreds of schools, hospitals,... 相似文献
109.
Cetin?Canpolat Shizhi?Qian Ali?BeskokEmail author 《Microfluidics and nanofluidics》2014,16(1-2):247-255
Induced-charge electro-osmotic (ICEO) flow of polymer-containing electrolyte solution around a cylindrical gold-coated stainless steel rod under AC electric field is measured by micro-particle image velocimetry (micro-PIV) for the first time. The ICEO flows as functions of the amount of non-ionic PEG (polyethylene glycol), cationic PDADMA (polydiallyldimethylammonium chloride), and anionic PVSASS (polyvinylsulfonic acid sodium salt) polymers added into the salt solution, frequency, and strength of the AC electric field are measured. The ICEO flow of polymer-containing fluid around the rod is quadrupolar with four vortices and is proportional to the square of imposed electric field. The ICEO flow velocity exponentially decreases with an increased concentration of neutral PEG. Ionic polyelectrolytes significantly increase ICEO velocities due to the enriched net charge within the induced electric double layer arising from the electrostatic interaction between the polarized rod’s surface and the charged polyelectrolytes in ionic polymer solution. In addition, polymer concentration affects the dependence of the ICEO flow on the frequency of AC electric field. 相似文献
110.
Nonionic polyacrylamide (PAAm) hydrogels were synthesized using three methods: room temperature polymerization, cryo-polymerization, and modified cryo-polymerization. Anionic PAAm hydrogels were obtained after hydrolyzing the nonionic hydrogels under alkaline conditions. The composition of anionic hydrogels was characterized by Fourier transform infrared (FT-IR) spectroscopy and element analysis. Morphological studies showed that the hydrogels exhibited various pore structures when they were synthesized using different methods. An additional mechanism for the formation of cryogels was proposed. Investigation of the swelling properties of the hydrogels and analysis of the swelling kinetics showed that the hydrolyzed PAAm hydrogels had rapid pH-sensitive rates. 相似文献