全文获取类型
收费全文 | 118167篇 |
免费 | 12341篇 |
国内免费 | 6377篇 |
专业分类
电工技术 | 9056篇 |
技术理论 | 14篇 |
综合类 | 9056篇 |
化学工业 | 18255篇 |
金属工艺 | 6824篇 |
机械仪表 | 7524篇 |
建筑科学 | 9862篇 |
矿业工程 | 3893篇 |
能源动力 | 3716篇 |
轻工业 | 8124篇 |
水利工程 | 2662篇 |
石油天然气 | 5779篇 |
武器工业 | 1333篇 |
无线电 | 13909篇 |
一般工业技术 | 13220篇 |
冶金工业 | 4964篇 |
原子能技术 | 1500篇 |
自动化技术 | 17194篇 |
出版年
2024年 | 642篇 |
2023年 | 2293篇 |
2022年 | 4578篇 |
2021年 | 6043篇 |
2020年 | 4489篇 |
2019年 | 3548篇 |
2018年 | 3998篇 |
2017年 | 4373篇 |
2016年 | 3970篇 |
2015年 | 5532篇 |
2014年 | 6667篇 |
2013年 | 7855篇 |
2012年 | 8777篇 |
2011年 | 9109篇 |
2010年 | 8141篇 |
2009年 | 7654篇 |
2008年 | 7399篇 |
2007年 | 6616篇 |
2006年 | 6364篇 |
2005年 | 5159篇 |
2004年 | 3573篇 |
2003年 | 2772篇 |
2002年 | 2725篇 |
2001年 | 2300篇 |
2000年 | 2103篇 |
1999年 | 2044篇 |
1998年 | 1524篇 |
1997年 | 1269篇 |
1996年 | 1241篇 |
1995年 | 903篇 |
1994年 | 796篇 |
1993年 | 558篇 |
1992年 | 482篇 |
1991年 | 317篇 |
1990年 | 248篇 |
1989年 | 210篇 |
1988年 | 157篇 |
1987年 | 102篇 |
1986年 | 75篇 |
1985年 | 61篇 |
1984年 | 39篇 |
1983年 | 29篇 |
1982年 | 32篇 |
1981年 | 22篇 |
1980年 | 27篇 |
1979年 | 14篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1959年 | 12篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
彭国生 《石油化工安全环保技术》2002,18(6):1-4
天然气勘探开发具有高温、高压、高风险,安全技术及管理难度大等特点,通过实例分析天然气井存在的主要问题,提出应采取的关键安全技术及需要解决的问题。 相似文献
13.
湖南出土的楚汉丝织品,以马王堆一、三号汉墓所出为代表,其色彩反映了我国当时印染工艺技术所达到的高度水平,其纹饰则显示了鲜明的时代特征,表现了运动、气势和古拙的艺术风格,充满着神奇浪漫的色彩。 相似文献
14.
BACKGROUND: The enterococci have become important nosocomial pathogens. They can cause multiple site infections and enterococcal bacteremia becomes more frequently associated with a high mortality rate. Previous studies of enterococcal bacteremia showed a variety of results. To establish the significance and importance of enterococci as nosocomial pathogens in this hospital, to characterize their clinical pictures and to search for the risk factors for mortality, this retrospective study was performed. METHODS: There were 208 cases of enterococcal bacteremia which occurred from 1988 to 1992. Twenty-seven cases had no medical charts, dismissing possibility of evaluation. Finally, 181 cases of enterococcal bacteremia were analysed. RESULTS: One hundred and eighteen episodes were nosocomial infections. Polymicrobial bacteremia occurred in 68.5% of the patients and the most common co-isolate was Pseudomonas aeruginosa. Those patients (78.5%) with underlying diseases and malignancies were the most common underlying problems. The portal of entry could be found in 69.6 percent of patients, with the gastrointestinal tract the most common sources. Antimicrobial susceptibility testing showed high gentamicin resistance rate (89.5%), and ampicillin still had about 80 percent sensitivity rate. The group who received specific antibiotic therapy for enterococcus showed lower mortality (36.4% versus 47.6%). Only one case had infective endocarditis. Forty-nine patients suffered from septic shock, the cause of 30 deaths. Totally 75 patients died during hospitalization. Besides sepsis, another major cause of death was their underlying diseases itself. CONCLUSIONS: Enterococci have no doubt become important nosocomial pathogens and enterococcal bacteremia were associated with high mortality, especially in elderly patients with underlying diseases such as malignancy or diabetes. When clinically dealing with sepsis from the gastrointestinal or biliary tract, especially when previous cephalosporins therapy showed no response, the possibility of enterococcal bacteremia should always be considered. 相似文献
15.
通过分析钢水在结晶器内凝固的不均匀性及对钢水结晶的热量平衡计算,讨论连铸中间包钢水温度、结晶器冷却水流量及进出水温差对拉坯速度的影响。 相似文献
16.
本文用计算机数字模拟方法研究了电活性分子多层Z型L-B膜修饰电极的循环伏安行为。计算了电极与修饰L-B膜分子第一层之间的电荷转移速度常数K_o,L-B膜分子层间的电荷转移速度常数k_i;对峰电位差△E_p及阳极峰面积Q的影响,以及在不同条件下各层分子的氧化态分数随扫描时间的变化。为研究和设计电活性分子修饰电极的实际体系提供了大量数据和信息。 相似文献
17.
超细Fe3O4粒子表面包覆酞菁钴性质研究 总被引:3,自引:1,他引:2
本文研究了合成载氧体的金属有机化学液相淀积法制造工艺,所得产物经TEM、XPS、Moss-bauer谱和B-H仪等手段,研究了它的结构和磁性能。实验表明,酞青钴以薄层形式包覆在Fe_3O_4的表面,封闭了Fe_3O_4的表面孔洞,稳定了Fe_3O_4的物相,增强了磁性能。 相似文献
18.
A distributed problem solving system can be characterized as a group of individual cooperating agents running to solve common problems. As dynamic application domains continue to grow in scale and complexity, it becomes more difficult to control the purposeful behavior of agents, especially when unexpected events may occur. This article presents an information and knowledge exchange framework to support distributed problem solving. From the application viewpoint the article concentrates on the stock trading domain; however, many presented solutions can be extended to other dynamic domains. It addresses two important issues: how individual agents should be interconnected so that their resources are efficiently used and their goals accomplished effectively; and how information and knowledge transfer should take place among the agents to allow them to respond successfully to user requests and unexpected external situations. The article introduces an architecture, the MASST system architecture, which supports dynamic information and knowledge exchange among the cooperating agents. The architecture uses a dynamic blackboard as an interagent communication paradigm to facilitate factual data, business rule, and command exchange between cooperating MASST agents. The critical components of the MASST architecture have been implemented and tested in the stock trading domain, and have proven to be a viable solution for distributed problem solving based on cooperating agents 相似文献
19.
王鹏 《消防技术与产品信息》2002,(11):34-36
“网吧”等互联网上网服务营业场所 (以下简称网吧 )是集上网聊天、上网冲浪、发电子邮件、查寻资料、休闲娱乐于一体的公共娱乐场所 ,普遍受到人们特别是青少年的欢迎。网吧在给人们工作、学习、生活带来便利的同时 ,也带来了一定的火灾危险 ,震惊全国的北京海淀区“6 .16 -蓝极速”特大火灾事故就是一个典型的案例。网吧存在的突出消防安全问题 ,已经引起公安消防机构的重视 ,并纳入消防监督检查视线 ,部署开展了以网吧为重点的消防安全专项整治。网吧的消防安全现状如何 ,究竟有何火灾危险 ,如何防范 ,笔者谈了以下拙见。 一、网吧的… 相似文献
20.