全文获取类型
收费全文 | 27424篇 |
免费 | 2723篇 |
国内免费 | 1418篇 |
专业分类
电工技术 | 1307篇 |
技术理论 | 6篇 |
综合类 | 3472篇 |
化学工业 | 1773篇 |
金属工艺 | 704篇 |
机械仪表 | 1123篇 |
建筑科学 | 6822篇 |
矿业工程 | 1842篇 |
能源动力 | 765篇 |
轻工业 | 852篇 |
水利工程 | 2029篇 |
石油天然气 | 1135篇 |
武器工业 | 287篇 |
无线电 | 1861篇 |
一般工业技术 | 1641篇 |
冶金工业 | 1246篇 |
原子能技术 | 201篇 |
自动化技术 | 4499篇 |
出版年
2024年 | 49篇 |
2023年 | 323篇 |
2022年 | 686篇 |
2021年 | 762篇 |
2020年 | 782篇 |
2019年 | 623篇 |
2018年 | 553篇 |
2017年 | 754篇 |
2016年 | 849篇 |
2015年 | 927篇 |
2014年 | 1680篇 |
2013年 | 1496篇 |
2012年 | 1759篇 |
2011年 | 2071篇 |
2010年 | 1696篇 |
2009年 | 1822篇 |
2008年 | 1741篇 |
2007年 | 2089篇 |
2006年 | 1883篇 |
2005年 | 1579篇 |
2004年 | 1371篇 |
2003年 | 1244篇 |
2002年 | 1096篇 |
2001年 | 822篇 |
2000年 | 658篇 |
1999年 | 510篇 |
1998年 | 359篇 |
1997年 | 303篇 |
1996年 | 228篇 |
1995年 | 166篇 |
1994年 | 156篇 |
1993年 | 124篇 |
1992年 | 98篇 |
1991年 | 60篇 |
1990年 | 48篇 |
1989年 | 30篇 |
1988年 | 36篇 |
1987年 | 17篇 |
1986年 | 11篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1966年 | 3篇 |
1962年 | 3篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
61.
人类在漫长的进化过程中形成了对自然的本能需求,亲生物设计从生物进化的角度以更系统和更合理的方法将自然重新融入现代建筑环境,构建人与场所之间的积极交互。源于光、水、风、植物、动物等自然元素的亲生物色彩设计具有令人愉悦的艺术感染力,动态的视觉效果暗示着蓬勃的生命力,能够系统、清晰地传递复杂的环境信息,引发观者的情感共鸣和情感依恋。从环境疗愈的角度看,具有亲生物特征的色彩设计对改善患者在医疗空间中的体验,激发患者的自我康复能力具有重要意义。亲生物设计是可持续发展设计中不可或缺的一环,两者的结合有助于创造兼具低环境影响和高情感联系的设计,以实现真正和持久的可持续性发展。 相似文献
62.
价值观的传播是一个缓慢的过程,在当前工业文明向生态文明过渡的时期,如何有效地提升民众的生态意识是值得探讨的问题。以生态审美意识传播为切入点,通过了解国内外主流的室内环境生态评估指标体系的前后变化,总结当前室内环境生态评估的变化趋势及其主要特征;从指标体系的变化中分析生态审美价值观的渗透方式,探讨当代室内环境生态评估对生态审美价值观传播的促进作用。最后,通过实验设定针对室内传统营造技艺应用的评估工具,并且在评估工具的使用过程中展示传播的模式与效用,通过评估反馈再一次验证室内环境生态评估对生态审美价值观的正向传播作用。 相似文献
63.
64.
通过开展飞机振动环境谱的飞行实测,获取飞机设备舱、管路、部分飞机结构等振动环境情况,经过数据处理获取能够反映飞机实际使用下的振动环境数据,给出了典型任务剖面的功率谱密度处理结果,为飞机耐久性/损伤容限优化设计提供依据,进一步提高飞行的安全性和可靠性。 相似文献
65.
随着社会的不断发展,人们越来越重视露天矿的测绘工作。尤其是最近几年,无人机技术不断成熟,工程技术人员可以利用无人机进行露天矿方量计算,从而保证勘测工作的准确性与高效性。本文主要围绕无人机技术的相关概述进行分析,探讨利用无人机进行露天矿方量计算的有效途径,从而为相关技术人员提供一定的理论参考。 相似文献
66.
为将我国最严格水资源管理制度的实践与二元水循环理论相结合,提高“三条红线”控制指标的科学性与合理性,本文以SWAT模型为基础,通过改进子流域划分方法、添加经济社会模块和人工用水模块,对其人工侧支循环模拟进行了系统的完善,开发了基于SWAT的水量-水质-水效联合调控模型SWAT_WAQER。以广西南流江流域为例,从国民经济用水量、河道径流与水质等方面对模型进行校验,并在此基础上划分了2030年“三条红线”控制指标。结果表明:该模型性能良好,能够用于不同节水情景下的国民经济用水量、污染物排放量、水功能区水质达标结果分析,可以作为科学制定“三条红线”控制指标的有力支撑工具。 相似文献
67.
This study focused on the relationship between perceptions of an innovative environment and creative performance in a web-based synchronous environment. A total of 160 sophomores and juniors from the National Taiwan Normal University participated in a learning activity consisting of a pretest and posttest quasi-experimental design. Pearson’s correlation coefficients and analysis of covariance (ANCOVA) were used in data analysis. Results indicated a positive correlation between personal creative performance and a free, supportive, and innovative environment. Team support and organizational obstruction had less influence on personal creative performance. Compared with a traditional classroom, a synchronous environment added to innovative essence and helped learners do better in terms of novelty, feasibility, value, and creative product design overall. 相似文献
68.
A new method is described, in which 3D‐printed structures are implemented in bubble column reactors to dissolve the macroscopic and the microscopic influences. The effect of these structuring method on the fluid dynamic behavior, the gas distribution, mass transfer, and fluid velocity inside bubble columns is shown in this contribution. 相似文献
69.
The COVID-19 pandemic has affected the educational systems worldwide, leading to the near-total closures of schools, universities, and colleges. Universities need to adapt to changes to face this crisis without negatively affecting students’ performance. Accordingly, the purpose of this study is to identify and help solve to critical challenges and factors that influence the e-learning system for Computer Maintenance courses during the COVID-19 pandemic. The paper examines the effect of a hybrid modeling approach that uses Cloud Computing Services (CCS) and Virtual Reality (VR) in a Virtual Cloud Learning Environment (VCLE) system. The VCLE system provides students with various utilities and educational services such as presentation slides/text, data sharing, assignments, quizzes/tests, and chatrooms. In addition, learning through VR enables the students to simulate physical presence, and they respond well to VR environments that are closer to reality as they feel that they are an integral part of the environment. Also, the research presents a rubric assessment that the students can use to reflect on the skills they used during the course. The research findings offer useful suggestions for enabling students to become acquainted with the proposed system’s usage, especially during the COVID-19 pandemic, and for improving student achievement more than the traditional methods of learning. 相似文献
70.
Effect of hydrogen enrichment on performance,combustion, and emission of a methanol fueled SI engine
B.S. Nuthan Prasad Jayashish Kumar Pandey G.N. Kumar 《International Journal of Hydrogen Energy》2021,46(49):25294-25307
The study of potentially high rated alternative fuel (Methanol) for the IC engines is an exciting topic in the recent research advancement. However, the study of combination of methanol and hydrogen is considered to address both economic and environmental needs. Hydrogen with best combustion characteristics will compensate for the drawbacks of methanol as a fuel. In the present investigation hydrogen enrichment to methanol has shown a significant enhancement in performance and combustion; the overall emission has reduced substantially. The experiments for a different set of trials, including hydrogen enrichment ranging between 5% and 20% with 2.5% increment, the engine is operated with wide-open throttle (WOT) condition for different speeds. The increase in enrichment of hydrogen has shown a rise in BTE, BP, and a reduced BSEC value. The percentage increase in BTE is between 20 and 30%, and an increase in hydrogen beyond 12.5% would affect the volumetric efficiency, and thus performance declines after that. The exhaust emissions have a huge impact on hydrogen enrichment; CO, HC, and CO2 emission are reduced by 30–40%; however, an increase in cylinder temperature due to rapid combustion slightly increases the NOx emission. Thus hydrogen enriched methanol operating at higher compression ratio can improve the overall engine characteristics significantly. 相似文献