全文获取类型
收费全文 | 803篇 |
免费 | 100篇 |
国内免费 | 87篇 |
专业分类
电工技术 | 15篇 |
综合类 | 67篇 |
化学工业 | 31篇 |
金属工艺 | 2篇 |
机械仪表 | 19篇 |
建筑科学 | 32篇 |
矿业工程 | 5篇 |
能源动力 | 9篇 |
轻工业 | 20篇 |
水利工程 | 32篇 |
石油天然气 | 4篇 |
武器工业 | 4篇 |
无线电 | 62篇 |
一般工业技术 | 28篇 |
冶金工业 | 34篇 |
原子能技术 | 2篇 |
自动化技术 | 624篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 19篇 |
2016年 | 15篇 |
2015年 | 25篇 |
2014年 | 37篇 |
2013年 | 47篇 |
2012年 | 45篇 |
2011年 | 70篇 |
2010年 | 41篇 |
2009年 | 48篇 |
2008年 | 58篇 |
2007年 | 62篇 |
2006年 | 83篇 |
2005年 | 52篇 |
2004年 | 30篇 |
2003年 | 41篇 |
2002年 | 27篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 21篇 |
1998年 | 24篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 12篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 5篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有990条查询结果,搜索用时 15 毫秒
1.
介绍了用工业钛白废酸提取粉煤灰中铝的新技术 ,试验研究了浸出过程中各因素对浸出率的影响 ,提出了最佳浸出工艺条件 .这为用钛白废酸提取粉煤灰中铝提供了新的方法 ,并为综合利用钛白废酸和粉煤灰又开辟了一个新的途径 .利用钛白废酸从粉煤灰中提取铝将具有较大的环境、经济和社会效益 . 相似文献
2.
Vivek Kant 《Theoretical Issues in Ergonomics Science》2018,19(2):195-212
Analysis of everyday work practices in sociotechnical systems for eliciting design/intervention requirements involves appropriate work analysis frameworks. The current article provides an extension to one such framework — Cognitive Work Analysis (CWA) — by scrutinising its sociotechnical basis. CWA's forte depends on its ‘design for adaptation’, system related operations, and operators. In contrast, sociotechnical work systems require not only operators and adaptation, but also a significant emphasis on ‘users’ and ‘appropriation’. The current article extends CWA (based on Rasmussen's original concepts) for users; subsequently allowing for system flexibility and possibilities of ‘appropriation’ within acceptable boundaries of the system's correct functioning. To this end, the first phase of Work Domain Analysis is extended by adding a new layer to the abstraction hierarchy (AH), based on Rasmussen's original insights. 相似文献
3.
Yanni PENG Xiaoping FAN Rong CHEN Ziyao YU Shi LIU Yunpeng CHEN Ying ZHAO Fangfang ZHOU 《Frontiers of Computer Science》2023,17(1):171701
Massive sequence view (MSV) is a classic timeline-based dynamic network visualization approach. However, it is vulnerable to visual clutter caused by overlapping edges, thereby leading to unexpected misunderstanding of time-varying trends of network communications. This study presents a new edge sampling algorithm called edge-based multi-class blue noise (E-MCBN) to reduce visual clutter in MSV. Our main idea is inspired by the multi-class blue noise (MCBN) sampling algorithm, commonly used in multi-class scatterplot decluttering. First, we take a node pair as an edge class, which can be regarded as an analogy to classes in multi-class scatterplots. Second, we propose two indicators, namely, class overlap and inter-class conflict degrees, to measure the overlapping degree and mutual exclusion, respectively, between edge classes. These indicators help construct the foundation of migrating the MCBN sampling from multi-class scatterplots to dynamic network samplings. Finally, we propose three strategies to accelerate MCBN sampling and a partitioning strategy to preserve local high-density edges in the MSV. The result shows that our approach can effectively reduce visual clutters and improve the readability of MSV. Moreover, our approach can also overcome the disadvantages of the MCBN sampling (i.e., long-running and failure to preserve local high-density communication areas in MSV). This study is the first that introduces MCBN sampling into a dynamic network sampling. 相似文献
4.
A universal method to prepare proton exchange membrane (PEM) with semi-interpenetrating polymer network (semi-IPN) via a versatile crosslinker 1,3-benzenedisulfonyl azide (1,3-BDSA) is proposed. Sulfonyl azide groups can react with any polymer with carbon-hydrogen bonds via hydrogen abstraction. Polyvinylidene fluoride (PVDF) and perfluorosulfonic acid (PFSA) polymer are selected as two precursors for semi-IPN. When 1,3-BDSA is heated to a sufficiently high temperature it can form the nitrene and connect with PVDF via hydrogen abstraction reaction, recombination, or CH-bond insertion. The crosslinking structure of PVDF is formed, and semi-IPN is constructed in the presence of PFSA at the same time. The mechanical properties, degree of crosslinking, water uptake, and proton conductivity of semi-IPN membranes are investigated. Compared with pure PFSA membrane, the mechanical properties and the dimensional stability of the semi-IPN membranes are improved significantly. The tensile strength of the composite membrane (27.2 MPa) is much higher than that of PFSA membrane (10.1 MPa). The maximum power density of the composite membrane can reach 382 mW cm−2 at 940 mA cm−2. Sulfonyl azide based crosslinkers can be used to prepare semi-IPN or IPN PEMs from any paired polymers with carbon–hydrogen bonds. 相似文献
5.
《AEUE-International Journal of Electronics and Communications》2014,68(8):783-794
Online video nowadays has become one of the top activities for users and has become easy to access. In the meantime, how to manage such huge amount of video data and retrieve them efficiently has become a big issue. In this article, we propose a novel method for video abstraction based on fast clustering of the regions of interest (ROIs). Firstly, the key-frames in each shot are extracted using the average histogram algorithm. Secondly, the saliency and edge maps are generated from each key-frame. According to these two maps, the key points for the visual attention model can be determined. Meanwhile, in order to expand the regions surrounding the key points, several thresholds are calculated from the corresponding key-frame. Thirdly, based on the key points and thresholds, several regions of interest are expanded and thus the main content in each frame is obtained. Finally, the fast clustering method is performed on the key frames by utilizing their ROIs. The performance and effectiveness of the proposed video abstraction algorithm is demonstrated by several experimental results. 相似文献
6.
MARIO BUNGE 《国际通用系统杂志》2013,42(3):181-182
Van Rootselaar criticizes some points in my theory of things for being allegedly trivial, others for being mistaken. While some results are indeed mathematically trivial they are not so philosophically. As for the mistakes, some arc undoubtedly there, most can be corrected easily, and others require changes that have been introduced in the final version of the theory. The rest arc not mistakes but misunderstandings, perhaps unavoidable given the brevity of the original paper. 相似文献
7.
Antoine Debuigne Marie HurtgenChristophe Detrembleur Christine JérômeChristopher Barner-Kowollik Thomas Junkers 《Progress in Polymer Science》2012,37(7):1004-1030
The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system. 相似文献
8.
试图结合日本战后社会、经济、文化等各方面发展的不同阶段,把日本现代建筑的发展历程划分为五个不同的时期,通过分析各个时期具有代表性的建筑师及其作品,梳理出日本在吸收、消化西方现代建筑理念的基础上,融合本国传统的木结构建筑文化,逐步建构、生成了具有独特风格的日本现代建筑的脉络。 相似文献
9.
10.