全文获取类型
收费全文 | 56234篇 |
免费 | 2315篇 |
国内免费 | 371篇 |
专业分类
电工技术 | 826篇 |
综合类 | 572篇 |
化学工业 | 10545篇 |
金属工艺 | 1234篇 |
机械仪表 | 1461篇 |
建筑科学 | 2803篇 |
矿业工程 | 292篇 |
能源动力 | 1607篇 |
轻工业 | 4901篇 |
水利工程 | 667篇 |
石油天然气 | 293篇 |
武器工业 | 32篇 |
无线电 | 4822篇 |
一般工业技术 | 8848篇 |
冶金工业 | 10238篇 |
原子能技术 | 436篇 |
自动化技术 | 9343篇 |
出版年
2023年 | 291篇 |
2022年 | 462篇 |
2021年 | 1132篇 |
2020年 | 716篇 |
2019年 | 937篇 |
2018年 | 1144篇 |
2017年 | 1040篇 |
2016年 | 1217篇 |
2015年 | 1093篇 |
2014年 | 1558篇 |
2013年 | 3365篇 |
2012年 | 2450篇 |
2011年 | 3041篇 |
2010年 | 2374篇 |
2009年 | 2341篇 |
2008年 | 2582篇 |
2007年 | 2576篇 |
2006年 | 2287篇 |
2005年 | 2034篇 |
2004年 | 1847篇 |
2003年 | 2015篇 |
2002年 | 2231篇 |
2001年 | 1712篇 |
2000年 | 1132篇 |
1999年 | 1122篇 |
1998年 | 1907篇 |
1997年 | 1429篇 |
1996年 | 1181篇 |
1995年 | 998篇 |
1994年 | 835篇 |
1993年 | 856篇 |
1992年 | 690篇 |
1991年 | 438篇 |
1990年 | 563篇 |
1989年 | 522篇 |
1988年 | 449篇 |
1987年 | 464篇 |
1986年 | 422篇 |
1985年 | 567篇 |
1984年 | 500篇 |
1983年 | 407篇 |
1982年 | 378篇 |
1981年 | 383篇 |
1980年 | 367篇 |
1979年 | 330篇 |
1978年 | 296篇 |
1977年 | 325篇 |
1976年 | 398篇 |
1975年 | 245篇 |
1973年 | 214篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
The workforce ageing phenomenon is recently affecting most of the Organisation for Economic Co-operation and Development (OECD) member countries, due to a general ageing of their populations and a higher average retirement age of the workforce. In this paper, the topic of ageing workforce management is addressed from a production research standpoint, with the aim of understanding how older workers can be supported and involved in a manufacturing system. First, the current state of the art related to the ageing workforce in production systems is presented. This is structured according to four main topics: (1) analysis and evaluation of ageing workers’ functional capacities, (2) consideration of ageing workers’ capacities in industrial system modelling and management, (3) analysis and exploitation of ageing workers’ expertise, (4) acknowledgement, analysis, design and integration of supporting technologies. Next, the discussion on the impact of the ageing workforce on manufacturing systems’ performances leads to the comparison of some technological advances that are related to the Industry 4.0 paradigms. Finally, a future research agenda on this topic is proposed, based on the same topics classification proposed for the literature analysis. Five different research areas are derived, suggesting future directions for appropriate research concerning the employ of older workers in production environments. 相似文献
23.
24.
25.
Sawao Honda Shinobu Hashimoto Benoît Nait-Ali David S. Smith Yusuke Daiko Yuji Iwamoto 《Journal of the American Ceramic Society》2022,105(10):6335-6344
Porous alumina with a highly textured microstructure was fabricated by pulse electric current sintering (PECS) using alumina platelets. Highly oriented porous alumina with a porosity of 3%–50% was obtained by a pressure-controlled method of PECS. The properties of the highly textured porous alumina were measured in two directions. The nitrogen gas permeance and thermal conductivity at room temperature were higher in the direction along the platelet length due to the higher continuity of pores and the connectivity of alumina platelets, respectively. The anisotropy of the thermal conductivity at room temperature was investigated and explained by the effect of grain size of platelets as well as morphology and orientation of pores. The bending strength was higher with the loading direction along the platelet thickness. The thermal shock strength was clearly different in the two directions. The difference in the thermal shock strength was investigated by the measurement of properties and thermal stress analysis. 相似文献
26.
27.
28.
29.
Titania-based ceramics with adjustable anatase-rutile fractions were obtained by milling of anatase, quartz and corundum precursors, uniaxial pressing and firing at 1100?°C. The influence of silica and alumina, combined with milling time and compaction pressure, was studied by design of experiments. The L9 orthogonal array with a three-level noise factor was employed. Firing of pure titania at 1100?°C yielded complete anatase to rutile transformation (ART), whereas stabilized samples show that an optimum amount of 9% silica and 33% alumina reduces phase transformation to only about 5?wt% rutile. An extended correlation matrix combined with analysis of variance (ANOVA) was applied to assess the combined effects of quartz, alumina, milling time and uniaxial compressing pressure on relative density, and anatase to rutile transformation. Results show absence of ART after milling, and controlled partial conversion of anatase to rutile after firing. Very good fitting was obtained by multivariate analysis on considering first and second order terms for dependence on silica contents and interactions between silica and each of the remaining factors, including milling time. This empirical dependence could be interpreted on a sound physicochemical basis, allowing the prediction of suitable compositions and processing conditions to obtain rutile-free samples by conventional ceramic processing, and to design ceramic samples with controlled fractions of anatase and rutile. 相似文献
30.
Load testing of applications is an important and costly activity for software provider companies. Classical solutions are very difficult to set up statically, and their cost is prohibitive in terms of both human and hardware resources. Virtualized cloud computing platforms provide new opportunities for stressing an application's scalability, by providing a large range of flexible and less expensive (pay‐per‐use model) computation units. On the basis of these advantages, load testing solutions could be provided on demand in the cloud. This paper describes a Benchmark‐as‐a‐Service solution that automatically scales the load injection platform and facilitates its setup according to load profiles. Our approach is based on: (i) virtualization of the benchmarking platform to create self‐scaling injectors; (ii) online calibration to characterize the injector's capacity and impact on the benched application; and (iii) a provisioning solution to appropriately scale the load injection platform ahead of time. We also report experiments on a benchmark illustrating the benefits of this system in terms of cost and resource reductions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献