全文获取类型
收费全文 | 30276篇 |
免费 | 2073篇 |
国内免费 | 1122篇 |
专业分类
电工技术 | 773篇 |
技术理论 | 2篇 |
综合类 | 3014篇 |
化学工业 | 559篇 |
金属工艺 | 526篇 |
机械仪表 | 1152篇 |
建筑科学 | 12415篇 |
矿业工程 | 1413篇 |
能源动力 | 408篇 |
轻工业 | 248篇 |
水利工程 | 1976篇 |
石油天然气 | 345篇 |
武器工业 | 74篇 |
无线电 | 861篇 |
一般工业技术 | 1191篇 |
冶金工业 | 603篇 |
原子能技术 | 166篇 |
自动化技术 | 7745篇 |
出版年
2024年 | 39篇 |
2023年 | 142篇 |
2022年 | 292篇 |
2021年 | 356篇 |
2020年 | 351篇 |
2019年 | 285篇 |
2018年 | 358篇 |
2017年 | 532篇 |
2016年 | 609篇 |
2015年 | 731篇 |
2014年 | 2173篇 |
2013年 | 1126篇 |
2012年 | 1943篇 |
2011年 | 2437篇 |
2010年 | 2055篇 |
2009年 | 1992篇 |
2008年 | 1829篇 |
2007年 | 2205篇 |
2006年 | 1976篇 |
2005年 | 1689篇 |
2004年 | 1383篇 |
2003年 | 1351篇 |
2002年 | 1156篇 |
2001年 | 952篇 |
2000年 | 831篇 |
1999年 | 815篇 |
1998年 | 800篇 |
1997年 | 618篇 |
1996年 | 526篇 |
1995年 | 413篇 |
1994年 | 264篇 |
1993年 | 231篇 |
1992年 | 187篇 |
1991年 | 148篇 |
1990年 | 99篇 |
1989年 | 80篇 |
1988年 | 104篇 |
1987年 | 42篇 |
1986年 | 56篇 |
1985年 | 74篇 |
1984年 | 54篇 |
1983年 | 39篇 |
1982年 | 20篇 |
1981年 | 28篇 |
1980年 | 14篇 |
1979年 | 28篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1974年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The next-generation systems are expected to be largely cyber–physical systems (CPSs) that autonomously control physical processes, through sensors and actuators typically in real-time feedback and cooperative control loops distributed among physical and cyber environments. The rapid technological advancements enhance the smartness of these CPSs, pushing their boundaries of performance and efficiency by embedding new information and communication technologies. However, to what extent CPSs should be smarter so that they do not compromise safety and security of safety critical systems? is an open research question. Towards this goal, the purpose of this study is to establish a grounded theory to analyse what makes these systems smart? and eventually, how to find a balance between smartness and safety risks? In this precinct, this article aims to develop a conceptual framework, define the dimensions and derive the characteristics that make CPSs smart. The proposed approach combines an automated informetric and systematic analysis of literature pertinent to the topic of smartness across anthropology, science, engineering and technology. The analysis of a case study building and the discussions presented herein support the connection between the existing understanding of CPSs and smartness offered by the building design approach in urban environment. 相似文献
2.
Bin Zhang Xuesong Jiang Fei Shen Xueming He Yong Fang Qiuhui Hu 《International Journal of Food Science & Technology》2021,56(6):2588-2595
This work intends to develop an online experimental system for screening of deoxynivalenol (DON) contamination in whole wheat meals by visible/near-infrared (Vis/NIR) spectroscopy and computer vision coupling technology. Spectral and image information of samples with various DON levels was collected at speed of 0.15 m s−1 on a conveyor belt. The two-type data were then integrated and subjected to chemometric analysis. Discriminant analysis showed that samples could be classified by setting 1000 μg kg−1 as the cut-off value. The best correct classified rate obtained in prediction was 93.55% based on fusion of spectral and image features, with reduced prediction uncertainty as compared to single feature. However, quantification of DON by quantitative analysis was not successful due to poor model performance. These results indicate that, although not accurate enough to provide conclusive result, this coupling technology could be adopted for rapid screening of DON contamination in cereals and feeds during processing. 相似文献
3.
A Distributed Virtual Environment (DVE) system offers a computer-generated virtual world in which individuals located at different
places in the physical world can interact with one another. In order to achieve real-time response for a large user base,
DVE systems need to have a scalable architecture. In this paper, we present the design of a grid-enabled service oriented
framework for facilitating the construction of scalable DVE systems on computing grids. A service component called “gamelet”
is proposed, whose distinctive mark is its high mobility for supporting dynamic load sharing. We propose a gamelet migration
protocol which can ensure the transparency and efficiency of gamelet migration, and an adaptive gamelet load-balancing (AGLB)
algorithm for making gamelet redistribution decisions at runtime. The algorithm considers both the synchronization costs of
the DVE system and network latencies inherent in the grid nodes. The activities of the users and the heterogeneity of grid
resources are also considered in order to carry out load sharing more effectively. We evaluate the performance of the proposed
mechanisms through a multiplayer online game prototype implemented using the Globus toolkit. The results show that our approach
can achieve faster response times and higher throughputs than some existing approaches.
This research is supported in part by the China National Grid project (863 program) and the HKU Foundation Seed Grant 28506002. 相似文献
4.
5.
从生产安全运行的管理要求;电压压降和电流的限制及信号的衰减;网络运行时间的要求;系统设计的影响;备用能力的考虑等各个方面,结合上海赛科聚苯乙烯项目的具体设计,分析隔爆条件下FF现场总线的H1网段负载能力的设计,以供大家探讨。 相似文献
6.
墙体裂缝的成因及防治 总被引:2,自引:2,他引:0
介绍了墙体裂缝的种类,从地基不均匀下沉、温度变化等方面分析了引起墙体裂缝的原因,介绍了墙体裂缝的预防措施和治理措施,以有效控制墙体裂缝的危害程度。 相似文献
7.
双排桩门架—锚杆新型组合支护体系的应用研究 总被引:1,自引:0,他引:1
本文分析了双排桩门架支护结构的受力机理。针对工程实际进行变形分析,提出增设锚杆形成锚杆———双排桩门架式组合支护体系的方法,并与监测数据对比、验证。 相似文献
8.
对CFG桩质量缺陷的探讨 总被引:2,自引:2,他引:0
根据具体工程的概况及水文地质条件,分析了CFG桩在地下水位出现大面积缩颈现象和复合地基载荷试验达不到设计要求的原因,并介绍了地基补强措施,以满足工程质量的要求。 相似文献
9.
在紧邻厂房中控室的基坑开挖中,根据复杂环境条件与施工要求,采用浅孔微差爆破并通过选取合理开沟掏槽位置来控制最小抵抗线方向以及控制一次最大起爆药量等措施,达到了控制飞石、降低爆破地震的效果,保证了爆破质量与爆破安全,提高了施工效率。 相似文献
10.
With the creation of a pattern recognition system for metal transfer mode, this article has collected five kinds of spectrum signals in gas metal arc welding (MIG, MAG and CO2) and take them as training samples. These samples have been pretreated by computer, several key characteristic parameters of the spectrum signal have been creatively extracted, and a corresponding recognition function and a minimum-distance-classifier have been constructed. The results show that the pattern recognition of several kinds of metal transfer modes for the metal gas arc welding can be done successfully, and relative important parameters in welding process, such as the frequency of droplet transfer and the approximate diameter of each droplet, can also be obtained. 相似文献