全文获取类型
收费全文 | 135969篇 |
免费 | 8607篇 |
国内免费 | 4373篇 |
专业分类
电工技术 | 9392篇 |
技术理论 | 20篇 |
综合类 | 14148篇 |
化学工业 | 8044篇 |
金属工艺 | 3178篇 |
机械仪表 | 6796篇 |
建筑科学 | 23294篇 |
矿业工程 | 4636篇 |
能源动力 | 2896篇 |
轻工业 | 16307篇 |
水利工程 | 7276篇 |
石油天然气 | 4009篇 |
武器工业 | 566篇 |
无线电 | 9211篇 |
一般工业技术 | 8216篇 |
冶金工业 | 8349篇 |
原子能技术 | 784篇 |
自动化技术 | 21827篇 |
出版年
2024年 | 361篇 |
2023年 | 1392篇 |
2022年 | 2462篇 |
2021年 | 3355篇 |
2020年 | 3360篇 |
2019年 | 2682篇 |
2018年 | 2456篇 |
2017年 | 3062篇 |
2016年 | 3587篇 |
2015年 | 3919篇 |
2014年 | 10043篇 |
2013年 | 8240篇 |
2012年 | 9720篇 |
2011年 | 10317篇 |
2010年 | 8128篇 |
2009年 | 8707篇 |
2008年 | 8221篇 |
2007年 | 9934篇 |
2006年 | 8883篇 |
2005年 | 7413篇 |
2004年 | 6480篇 |
2003年 | 5788篇 |
2002年 | 4783篇 |
2001年 | 3518篇 |
2000年 | 2818篇 |
1999年 | 2171篇 |
1998年 | 1436篇 |
1997年 | 1128篇 |
1996年 | 921篇 |
1995年 | 771篇 |
1994年 | 576篇 |
1993年 | 430篇 |
1992年 | 343篇 |
1991年 | 247篇 |
1990年 | 166篇 |
1989年 | 185篇 |
1988年 | 139篇 |
1987年 | 99篇 |
1986年 | 107篇 |
1985年 | 115篇 |
1984年 | 105篇 |
1983年 | 110篇 |
1982年 | 46篇 |
1981年 | 31篇 |
1980年 | 34篇 |
1979年 | 18篇 |
1977年 | 20篇 |
1975年 | 11篇 |
1961年 | 10篇 |
1959年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
71.
The objective of this paper is to review and document the mine fleet management systems’ models and algorithms. The purpose is to understand the algorithms behind the fleet management systems and the proposed academic solutions in this area to identify any gaps in the current literature and to open up opportunities to establish research questions that need to be addressed in an integrated simulation and optimisation operational planning research framework. In this paper, we review industrial fleet management systems and the main academic algorithms behind such systems. The fleet management systems are divided into three subsequently related problems to review: shortest path, production optimisation and real-time dispatching. Finally, the limitations of current algorithms for fleet management systems are documented in terms of mining practice feasibility and optimality of the solution on large-scale problems. The results of this literature review enable us to evaluate the logical links between major components of an integrated simulation and optimisation operational planning framework with current theory of fleet management systems. 相似文献
72.
Debadyuti Das 《国际生产研究杂志》2018,56(17):5776-5794
The present work is an attempt to investigate the adoption of sustainable supply chain management (SSCM) practices amongst manufacturing and process based organisations in India and its impact on organisational performance encompassing all three dimensions of sustainability. SSCM practices conceived in the present study include environmental management practices (EMP), socially inclusive practices for employees (SPE), socially inclusive practices for community (SPC), operations practices (OP) and supply chain integration (SCI) which were treated as exogenous variables. Organisational performance considered in this study includes five dimensions, namely environmental performance (EPR), employee-centred social performance (ESP), community-centred social performance (CSP), operations performance (OPR) and competitiveness, which were regarded as endogenous variables. The analysis was carried out with the help of structural equation modelling considering natural logarithm of manpower as a control variable. Few major findings are mentioned. EMP does not have any significant association with OPR, nor does it result in competitiveness. However, when jointly mediated through both EPR and OPR, EMP leads to competitiveness. SPC has significant negative association with competitiveness, when only direct relationship is considered. However, indirect relationship between SPC and competitiveness shows significant positive association when mediated through CSP. The resultant total effect between SPC and competitiveness turns out to be insignificant. Further, OPR fully mediates the relationship between OP and competitiveness. Managerial implications of the findings are discussed. 相似文献
73.
Galin Ivanov Ertugrul Bilgucu Ivelina Ivanova Milena Dimitrova 《International Journal of Dairy Technology》2020,73(3):563-569
The present study aimed to investigate the effect of somatic cell count (SCC) of raw cow's milk on the volatile organic compound (VOC) profiles of yoghurt. Test yoghurt samples were produced from three batches of cow's milk with low, medium and high SCC, respectively. The VOCs were determined by gas chromatography–mass spectrometry (GC–MS) analysis. A lower diacetyl and acetoin content and a higher content of 2‐heptanone, and butanoic and hexanoic acids were established in the yoghurt samples from batches with high SCC of above 1 000 000 cells/cm3. The increased SCC of cow's milk had a negative effect on the volatile organic compound profiles of yoghurt. 相似文献
74.
75.
对首钢1号高炉焦炭质量恶化后增产节焦的生产经验进行了总结分析。认为提高入炉原燃料质量,综合优化高炉基本制度,合理控制稳定的操作炉型是保证炉况长期顺稳、实现效益最大化的有效手段。 相似文献
76.
由于AD HOC网络自身的特点,其网络管理很多方面与固定网络不同,如移动性管理和体系结构管理等。讨论了AD HOC网络管理的各个方面,并列举了各个方面的设计思路和已有的相关算法的简介。 相似文献
77.
硫化物预处理方法研究及测定中的质量保证 总被引:1,自引:0,他引:1
针对水和废水中硫离子的特点,设计制作了测定硫化物的酸化—吹气—吸收预处理装置,并验证了该装置对硫化物的回收效果,简化了原来的预处理方法。总结分光测定过程中注意的若干事项,确定了最佳实验条件,使该方法具有更准确、简便、快速的特点。 相似文献
78.
79.
梁斌 《冶金标准化与质量》2006,44(6):41-43
质量管理永远是企业生命的源泉,质量管理体系是一个复杂的系统工程,企业只有不断完善质量体系,进行质量管理创新,保持质量管理体系的长期有效的进行,才能在市场竞争中保持领先。 相似文献
80.