全文获取类型
收费全文 | 5790篇 |
免费 | 1020篇 |
国内免费 | 907篇 |
专业分类
电工技术 | 209篇 |
综合类 | 457篇 |
化学工业 | 1102篇 |
金属工艺 | 64篇 |
机械仪表 | 162篇 |
建筑科学 | 186篇 |
矿业工程 | 45篇 |
能源动力 | 116篇 |
轻工业 | 3653篇 |
水利工程 | 28篇 |
石油天然气 | 29篇 |
武器工业 | 21篇 |
无线电 | 234篇 |
一般工业技术 | 800篇 |
冶金工业 | 71篇 |
原子能技术 | 33篇 |
自动化技术 | 507篇 |
出版年
2024年 | 45篇 |
2023年 | 142篇 |
2022年 | 159篇 |
2021年 | 222篇 |
2020年 | 198篇 |
2019年 | 209篇 |
2018年 | 142篇 |
2017年 | 181篇 |
2016年 | 181篇 |
2015年 | 197篇 |
2014年 | 365篇 |
2013年 | 387篇 |
2012年 | 496篇 |
2011年 | 530篇 |
2010年 | 390篇 |
2009年 | 410篇 |
2008年 | 297篇 |
2007年 | 473篇 |
2006年 | 422篇 |
2005年 | 378篇 |
2004年 | 318篇 |
2003年 | 315篇 |
2002年 | 268篇 |
2001年 | 225篇 |
2000年 | 176篇 |
1999年 | 123篇 |
1998年 | 91篇 |
1997年 | 67篇 |
1996年 | 68篇 |
1995年 | 56篇 |
1994年 | 31篇 |
1993年 | 32篇 |
1992年 | 25篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1968年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有7717条查询结果,搜索用时 15 毫秒
71.
《影响评估与项目评价》2013,31(3):163-174
Efforts have been made to mainstream the environment in European Commission (EC) development co-operation. In programming, the main tool is the Country Environmental Profile (CEP) which informs, from an environmental point of view, the preparation of Country Strategy Papers (CSPs). Recently CEPs have improved significantly; they have different entry points in CSPs and the results of environmental integration can be found in a series of ‘environmental integration outputs’. This paper describes the structure of CEPs, their place in the EC cycle of operations and how they can influence CSPs. It shows, through case studies, the impact CEPs are having on CSPs, resulting in CSPs that prepare the ground for more effective environmental integration throughout the cycle of operations. 相似文献
72.
介绍了芳纶纤维布粘贴加固旧桥施工的工艺原理,对其施工工艺流程作了简要论述,并对施工准备、混凝土表面清理、涂刷底胶、粘贴、加固等工序的操作要点进行了详细阐述,给出了施工质量控制措施,指出该工法具有良好的社会效益和经济效益。 相似文献
73.
This paper studies the cognitive broadcast channel in which the primary user com- municates to the primary receiver, while the secondary user has noncausal knowledge of the primary radio's codeword and expects to communicate to two secondary receivers. Comparing with the existing cognitive radio channel which considers only one secondary receiver, cognitive broadcast channel studies the case that there are multiple secondary receivers. To this end, we investigate the fundamental limits of the performance of the Gaussian cognitive broadcast channel from the information theoretic perspective. Specifically, we derive the capacity region of the Gaussian cognitive degraded broadcast channel with weak interference. 相似文献
74.
75.
In complicated systems, such as a highly integrated industrial plant with its own energy production, estimating the value of energy conservation is not so straightforward. Often, heat is priced using different kinds of methods for allocating the fuel cost to heat and electricity. However, there is no consistent way to valuate the process steam in industry, and not just one useful method for allocating costs to heat and power. In this paper, the energy method, exergy method, benefit distribution method and market‐based method are evaluated and compared from different decision‐making perspectives. The results of this study indicate that the allocation methods may overestimate by up to 200–300% the benefits from the mill perspective compared to the benefits from the mill site perspective. So, the most suitable method may vary, depending on the selected system boundary, i.e. the decision‐making perspective, the type of CHP plant and energy prices. Based on the results of this study, the exergy method fits well with the CCGT plant with a condensing unit and constant fuel input. On the other hand, the market‐based method is the most correct way to estimate the value of heat when heat conservation reduces the production of CHP electricity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
76.
77.
78.
79.
Rungsinee Sothornvit Chaiyaporn Sampoompuang 《International Journal of Food Science & Technology》2012,47(3):511-517
Rice straw contains cellulose as its main carbohydrate component, which is the major constituent for making rice straw paper as an alternative use of the residue. The objectives of this study were to determine a rice straw paper‐making process incorporating activated carbon (AC) and the effect of AC and the glucomannan (GLU) content on the physical and mechanical properties, including the ethylene adsorption capacity of rice straw paper containing AC. The results showed that AC was an effective ethylene scavenger, and it was possible to incorporate it into the rice straw paper‐making process. Increasing the AC content increased the ethylene adsorption capacity but decreased the strength of the AC‐rice straw paper. GLU maintained the strength of the rice straw paper but did not affect the ethylene adsorption capacity. Incorporation of 30% AC content with 0.3% GLU in the AC‐rice straw paper produced the maximum level of ethylene scavenging (77%). Moreover, AC‐rice straw paper is an environmentally friendly material owing to its reusability, and it has the potential for applications in food and agricultural packaging because it can act as an ethylene scavenger and also provide protection against mechanical damage. 相似文献
80.
针对YB45型包装机框架纸在传送过程中位置偏移的问题,通过对框架纸吸风脚的改进,由此提高框架纸传送过程中吸附稳定性,解决了因框架纸传送过程中位置偏移而引起停机及产品品质问题。 相似文献