全文获取类型
收费全文 | 588898篇 |
免费 | 51279篇 |
国内免费 | 22465篇 |
专业分类
电工技术 | 32770篇 |
技术理论 | 71篇 |
综合类 | 34497篇 |
化学工业 | 105758篇 |
金属工艺 | 30393篇 |
机械仪表 | 35405篇 |
建筑科学 | 46155篇 |
矿业工程 | 16745篇 |
能源动力 | 16460篇 |
轻工业 | 41687篇 |
水利工程 | 9879篇 |
石油天然气 | 34110篇 |
武器工业 | 4417篇 |
无线电 | 68254篇 |
一般工业技术 | 73538篇 |
冶金工业 | 30285篇 |
原子能技术 | 5516篇 |
自动化技术 | 76702篇 |
出版年
2024年 | 2197篇 |
2023年 | 8139篇 |
2022年 | 14888篇 |
2021年 | 20782篇 |
2020年 | 16761篇 |
2019年 | 15134篇 |
2018年 | 17010篇 |
2017年 | 19433篇 |
2016年 | 18198篇 |
2015年 | 23482篇 |
2014年 | 29643篇 |
2013年 | 36668篇 |
2012年 | 36525篇 |
2011年 | 40500篇 |
2010年 | 35392篇 |
2009年 | 34129篇 |
2008年 | 33019篇 |
2007年 | 31673篇 |
2006年 | 32207篇 |
2005年 | 28283篇 |
2004年 | 19101篇 |
2003年 | 16859篇 |
2002年 | 15423篇 |
2001年 | 14004篇 |
2000年 | 14107篇 |
1999年 | 15563篇 |
1998年 | 13190篇 |
1997年 | 10921篇 |
1996年 | 10080篇 |
1995年 | 8495篇 |
1994年 | 6968篇 |
1993年 | 5137篇 |
1992年 | 4074篇 |
1991年 | 3162篇 |
1990年 | 2493篇 |
1989年 | 2061篇 |
1988年 | 1646篇 |
1987年 | 1154篇 |
1986年 | 903篇 |
1985年 | 662篇 |
1984年 | 449篇 |
1983年 | 396篇 |
1982年 | 347篇 |
1981年 | 273篇 |
1980年 | 268篇 |
1979年 | 163篇 |
1978年 | 94篇 |
1977年 | 101篇 |
1976年 | 135篇 |
1975年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
涤纶复合丝(POY+DTY)的研发 总被引:1,自引:0,他引:1
DTY和POY网络复合丝是以聚酯直纺生产的两种不同规格的POY丝为原料,通过对加弹机进行适当改造,利用不同的加工路线,使一股POY丝经过加捻后形成DTY,再与另一股POY丝网络合股形成包芯复合丝.该复合丝利用POY丝和DTY丝的收缩差异和染色差异等不同风格特性,使得布面形成一种具有雪花状的色丁效果.该复合丝属于差别化纤维,是国家鼓励发展的项目,它具有优良的吸湿排汗性能和弹性保暖性能,是保暖内衣的首选面料,市场前景广阔. 相似文献
102.
103.
Feng Wang Chong-Wah Ngo Ting-Chuen Pong 《Multimedia, IEEE Transactions on》2008,10(5):926-935
104.
Lie‐Fern Hsu 《Quality and Reliability Engineering International》2007,23(2):269-272
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
105.
磷矿中七种金属元素的光谱法测定 总被引:2,自引:0,他引:2
研究了磷矿样品中7种金属元素锰、钴、镍,锌、铬、钼及铋的分析方法,选择了灵敏度高干扰少的谱线,绘制出工作曲线,对样品进行了科学处理,不必进行化学分离即可对七种元素同时测定,经合成样分析、回收实验及样品测定,证明此方法精确可靠,其回收率在98%-102%之间。 相似文献
106.
Yanqing Ji Hao Ying John Yen Shizhuo Zhu Daniel C. Barth‐Jones Richard E. Miller R. Michael Massanari 《国际智能系统杂志》2007,22(8):827-845
Discovering unknown adverse drug reactions (ADRs) in postmarketing surveillance as early as possible is highly desirable. Nevertheless, current postmarketing surveillance methods largely rely on spontaneous reports that suffer from serious underreporting, latency, and inconsistent reporting. Thus these methods are not ideal for rapidly identifying rare ADRs. The multiagent systems paradigm is an emerging and effective approach to tackling distributed problems, especially when data sources and knowledge are geographically located in different places and coordination and collaboration are necessary for decision making. In this article, we propose an active, multiagent framework for early detection of ADRs by utilizing electronic patient data distributed across many different sources and locations. In this framework, intelligent agents assist a team of experts based on the well‐known human decision‐making model called Recognition‐Primed Decision (RPD). We generalize the RPD model to a fuzzy RPD model and utilize fuzzy logic technology to not only represent, interpret, and compute imprecise and subjective cues that are commonly encountered in the ADR problem but also to retrieve prior experiences by evaluating the extent of matching between the current situation and a past experience. We describe our preliminary multiagent system design and illustrate its potential benefits for assisting expert teams in early detection of previously unknown ADRs. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 827–845, 2007. 相似文献
107.
Yun‐Hwei Shen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(5):581-586
A novel strategy of sweep coagulation to treat low turbidity water is presented herein. Study findings demonstrated that an Na+‐saturated bentonite with medium cation exchange capacity (CEC) resulted in significant turbidity removal at a bentonite dosage of 30 mg dm?3. Bentonite dispersion with fully delaminated platelets tended to undergo a more porous type of coagulation with intense face‐to‐face interactions of platelets and effectively entrapped TiO2 particles in band‐type structures. This type of coagulation usually results in a large volume of settled flocs with a fluffy structure and excellent turbidity removal efficiency for sweep coagulation. The sign and magnitude of electrical charge on TiO2 particles has a minor effect on the efficiency of sweep coagulation. Copyright © 2005 Society of Chemical Industry 相似文献
108.
Hung‐Yee Shu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(3):273-280
Liquid–liquid two‐phase epoxidation from cyclohexene and cyclooctene in aqueous potassium peroxymonosulfate (commercially available as Oxone®) solution was studied as an application in pollution prevention. To avoid potential emissions of volatile organic compounds an aqueous solution was employed to replace the usual chlorinated solvents used in epoxide production. A droplet column reactor and stirred tank reactor were used to investigate two‐phase synthesis of epoxide. An aqueous Oxone® solution was used to oxidize a dispersion of alkene droplets and form epoxide. The study of aqueous epoxidation in both reactors showed that the epoxidation of alkenes can be represented as a first order reaction with respect to alkene. The salting out effect of Oxone® concentration was studied in both reactors and found to be very similar at optimal conditions. In comparing the two reactors, it was found that the droplet column reactor produces larger quantities of product per unit reactor volume for the same reaction time. The objective of this study is to provide an alternative reactor design and synthesis route that can meet pollution prevention goals. Copyright © 2004 Society of Chemical Industry 相似文献
109.
110.
该文介绍了Mall的产生条件和国内发展概况,并结合实例分析,着重论述建筑设计方面的有关问题。 相似文献