全文获取类型
收费全文 | 10107篇 |
免费 | 845篇 |
国内免费 | 640篇 |
专业分类
电工技术 | 485篇 |
综合类 | 1208篇 |
化学工业 | 827篇 |
金属工艺 | 743篇 |
机械仪表 | 1066篇 |
建筑科学 | 1093篇 |
矿业工程 | 502篇 |
能源动力 | 310篇 |
轻工业 | 317篇 |
水利工程 | 328篇 |
石油天然气 | 479篇 |
武器工业 | 112篇 |
无线电 | 679篇 |
一般工业技术 | 891篇 |
冶金工业 | 417篇 |
原子能技术 | 109篇 |
自动化技术 | 2026篇 |
出版年
2024年 | 10篇 |
2023年 | 68篇 |
2022年 | 134篇 |
2021年 | 163篇 |
2020年 | 191篇 |
2019年 | 164篇 |
2018年 | 203篇 |
2017年 | 251篇 |
2016年 | 272篇 |
2015年 | 297篇 |
2014年 | 437篇 |
2013年 | 541篇 |
2012年 | 660篇 |
2011年 | 759篇 |
2010年 | 535篇 |
2009年 | 611篇 |
2008年 | 588篇 |
2007年 | 769篇 |
2006年 | 646篇 |
2005年 | 689篇 |
2004年 | 563篇 |
2003年 | 527篇 |
2002年 | 460篇 |
2001年 | 387篇 |
2000年 | 329篇 |
1999年 | 252篇 |
1998年 | 169篇 |
1997年 | 199篇 |
1996年 | 150篇 |
1995年 | 128篇 |
1994年 | 85篇 |
1993年 | 84篇 |
1992年 | 64篇 |
1991年 | 20篇 |
1990年 | 25篇 |
1989年 | 21篇 |
1988年 | 25篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1966年 | 6篇 |
1964年 | 3篇 |
1962年 | 3篇 |
1957年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Juan José Burbano He/him Darío Marcelino Cabezas María Jimena Correa 《International Journal of Food Science & Technology》2022,57(8):4772-4781
Walnut flour (WF), a by-product of walnut oil production, is characterised by high polyunsaturated fatty acids, proteins, and fibre contents and presents suitability for bakery products. However, when using non-traditional ingredients, it is essential to evaluate the effect on the quality properties of the final product. So, this work aimed to assess the impact of WF on the technological, physicochemical, and sensory properties of gluten-free (GF) cakes. WF was added at a flour blend (cassava (CS) and maize (MS) starches and rice flour) at 0, 10%, 15%, and 20%. The results showed that WF modified starch gelatinisation, increased amylose–lipid complex (ALC) content, and made crumbs easier to chew. Besides, the total dietary fibre (TDF) and protein content significantly increased. Cakes with 15% WF presented the highest specific volume (SV) and no differences in overall acceptability with respect to control. Hence, WF is a suitable ingredient for gluten-free bakery products. 相似文献
2.
Software is a central component in the modern world and vastly affects the environment’s sustainability. The demand for energy and resource requirements is rising when producing hardware and software units. Literature study reveals that many studies focused on green hardware; however, limited efforts were made in the greenness of software products. Green software products are necessary to solve the issues and problems related to the long-term use of software, especially from a sustainability perspective. Without a proper mechanism for measuring the greenness of a particular software product executed in a specific environment, the mentioned benefits will not be attained. Currently, there are not enough works to address this problem, and the green status of software products is uncertain and unsure. This paper aims to identify the green measurements based on sustainable dimensions in a software product. The second objective is to reveal the relationships between the elements and measurements through empirical study. The study is conducted in two phases. The first phase is the theoretical phase, where the main components, measurements and practices that influence the sustainability of a software product are identified. The second phase is the empirical study that involved 103 respondents in Malaysia investigating current practices of green software in the industrial environment and further identifying the main sustainability dimensions and measurements and their impact on achieving green software products. This study has revealed seven green measurements of software product: Productivity, Usability, Cost Reduction, Employee Support, Energy Efficiency, Resource Efficiency and Tool Support. The relationships are statistically significant, with a significance level of less than 0.01 (p = 0.000). Thus, the hypothesised relationships were all accepted. The contributions of this study revolve around the research perspectives of the measurements to attain a green software product. 相似文献
3.
Besides entertainment, games have shown to have the potential to impact a broader variety of cognitive abilities. Research has consistently shown that several aspects in cognition such as visual short-memory, multitasking and spatial skills can be enhanced by game play. In a previous study, it was found that playing Monkey Tales, a game aimed at training arithmetic skills, helped second grade pupils to increase their accuracy in mental calculation as compared to paper exercises. In this follow up study we explore whether traditional methods and game training differ in terms of the cognitive processes that both are able to impact. We incorporated standardized measures of working memory and visuo-motor skills. Additionally, the mathematics game was modified and its contents extracted to allow precise comparison between the gaming and paper exercises condition. Thus each single math exercise, type of question (e.g., multiple choice), quantity and order was perfectly matched in the game training and the traditional training conditions. Gains in arithmetical performance, and self-reported measures of enjoyment were also investigated. We found some evidence suggesting that arithmetic performance enhancement induced by game play and paper exercises differ not only in terms of enjoyment but also of working memory capacity improvements. 相似文献
4.
5.
This paper investigates the N-policy M/M/1 queueing system with working vacation and server breakdowns. As soon as the system becomes empty, the server begins a working vacation. The server works at a lower service rate rather than completely stopping service during a vacation period. The server may break down with different breakdown rates during the idle, working vacation, and normal busy periods. It is assumed that service times, vacation times, and repair times are all exponentially distributed. We analyze this queueing model as a quasi-birth–death process. Furthermore, the equilibrium condition of the system is derived for the steady state. Using the matrix-geometric method, we find the matrix-form expressions for the stationary probability distribution of the number of customers in the system and system performance measures. The expected cost function per unit time is constructed to determine the optimal values of the system decision variables, including the threshold N and mean service rates. We employ the particle swarm optimization algorithm to solve the optimization problem. Finally, numerical results are provided, and an application example is given to demonstrate the applicability of the queueing model. 相似文献
6.
This paper summarizes the basics of pulsed thermal nondestructive testing (TNDT) including theoretical solutions, data processing algorithms and practical implementation. Typical defects are discussed along with 1D analytical and multi-dimensional numerical solutions. Special emphasis is focused on defect characterization by the use of inverse solutions. A list of TNDT terms is provided. Applications of active TNDT, mainly in the aerospace industry, are discussed briefly, and some trends in the further development of this technique are described. 相似文献
7.
8.
Lance Charles E.; Lambert Tracy A.; Gewin Amanda G.; Lievens Filip; Conway James M. 《Canadian Metallurgical Quarterly》2004,89(2):377
The authors reanalyzed assessment center (AC) multitrait-multimethod (MTMM) matrices containing correlations among postexercise dimension ratings (PEDRs) reported by F. Lievens and J. M. Conway (2001). Unlike F. Lievens and J. M. Conway, who used a correlated dimension-correlated uniqueness model, we used a different set of confirmatory-factor-analysis-based models (1-dimension-correlated Exercise and 1-dimension-correlated uniqueness models) to estimate dimension and exercise variance components in AC PEDRs. Results of reanalyses suggest that, consistent with previous narrative reviews, exercise variance components dominate over dimension variance components after all. Implications for AC construct validity and possible redirections of research on the validity of ACs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Su Yu liangDepartment of Energy power Engineering Xi'an Jiaotong University Xi'an ChinaDepartment of petroleum Engineering Petroleum University Dongying ChinaZhang Ming yuan Yang Jian Zhang Chao jieDepartment of Energy power Engineering Xi'an Jiaotong University Xi'an ChinaLi Dong xia Department of petroleum Engineering Petroleum University Dongying China 《水动力学研究与进展(B辑)》2003,15(2)
NOMENCLATUREd———embeddingdimension ,dimensionlessCd(r)———correlationsum ,dimensionlessN———numberofpairsofpointsontherecon structedattractor,dimensionlessr———scalingdistance ,dimensionlessDc ———correlationdimension ,dimensionlessK———Kolmogoroventropy ,bits/sR… 相似文献
10.
地理空间信息网格调度技术,要比传统的高性能计算中的调度技术复杂,原因是如果将全部网格资源作为一个应用程序的调度和执行目标,必将导致通信延迟、成本昂贵、执行低效等。为此,综合考虑应用程序特性、机器特性等,研究设计了地理空间信息网格高性能调度技术中的应用程序调度模型,包括地理空间信息网格应用程序分析;资源特性分析;应用程序分解;性能预测;资源调度;机器选择;任务映射;任务调度;任务调度器和调度器管理模块。以实现为不同的应用程序匹配不同的计算资源,提高计算资源的利用率和应用程序的执行效率。 相似文献