全文获取类型
收费全文 | 10101篇 |
免费 | 398篇 |
国内免费 | 345篇 |
专业分类
电工技术 | 142篇 |
综合类 | 336篇 |
化学工业 | 103篇 |
金属工艺 | 26篇 |
机械仪表 | 90篇 |
建筑科学 | 4132篇 |
矿业工程 | 215篇 |
能源动力 | 154篇 |
轻工业 | 137篇 |
水利工程 | 190篇 |
石油天然气 | 29篇 |
武器工业 | 24篇 |
无线电 | 650篇 |
一般工业技术 | 180篇 |
冶金工业 | 43篇 |
原子能技术 | 15篇 |
自动化技术 | 4378篇 |
出版年
2024年 | 12篇 |
2023年 | 86篇 |
2022年 | 143篇 |
2021年 | 152篇 |
2020年 | 142篇 |
2019年 | 110篇 |
2018年 | 123篇 |
2017年 | 114篇 |
2016年 | 324篇 |
2015年 | 264篇 |
2014年 | 572篇 |
2013年 | 540篇 |
2012年 | 635篇 |
2011年 | 826篇 |
2010年 | 581篇 |
2009年 | 550篇 |
2008年 | 655篇 |
2007年 | 929篇 |
2006年 | 920篇 |
2005年 | 787篇 |
2004年 | 667篇 |
2003年 | 592篇 |
2002年 | 345篇 |
2001年 | 229篇 |
2000年 | 164篇 |
1999年 | 91篇 |
1998年 | 56篇 |
1997年 | 29篇 |
1996年 | 31篇 |
1995年 | 42篇 |
1994年 | 22篇 |
1993年 | 18篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2022,48(1):10-21
Pc-WLEDs are considered to play a spectacular role in future generation light sources in view of their outstanding energy efficiency. In this regard, Eu3+ activated BaY2ZnO5 phosphor was prepared and investigated by XRD, PL and SEM analyses. Rietveld refinement analysis was carried out to confirm the structure of the synthesized phosphor. The prepared phosphor shows an intense red emission around 627 nm under excitation by near UV light. The 5D0-7F2 transition intensity of the prepared phosphor is three times higher compared to the commercial (Y,Gd)BO3:Eu3+ red phosphor. The CIE colour coordinates of BaY2ZnO5:Eu3+ (9mol%) phosphor corresponds to be (0.6169, 0.3742) and it has a high 97.9 % colour purity. The obtained results reveal the utility of BaY2ZnO5:Eu3+ phosphor as an efficient red component in WLEDs, anti-counterfeiting and fingerprint detection applications. 相似文献
2.
Smartphones are being used and relied on by people more than ever before. The open connectivity brings with it great convenience and leads to a variety of risks that cannot be overlooked. Smartphone vendors, security policy designers, and security application providers have put a variety of practical efforts to secure smartphones, and researchers have conducted extensive research on threat sources, security techniques, and user security behaviors. Regrettably, smartphone users do not pay enough attention to mobile security, making many efforts futile. This study identifies this gap between technology affordance and user requirements, and attempts to investigate the asymmetric perceptions toward security features between developers and users, between users and users, as well as between different security features. These asymmetric perceptions include perceptions of quality, perceptions of importance, and perceptions of satisfaction. After scoping the range of smartphone security features, this study conducts an improved Kano-based method and exhaustively analyzes the 245 collected samples using correspondence analysis and importance satisfaction analysis. The 14 security features of the smartphone are divided into four Kano quality types and the perceived quality differences between developers and users are compared. Correspondence analysis is utilized to capture the relationship between the perceived importance of security features across different groups of respondents, and results of importance-satisfaction analysis provide the basis for the developmental path and resource reallocation strategy of security features. This article offers new insights for researchers as well as practitioners of smartphone security. 相似文献
3.
Software updates are an important topic for increasingly software dependent and automated automotive systems. Besides ongoing technical developments, there are also regulatory requirements in development for such systems. We present here an overview of the automotive domain and the particular requirements on update systems, identify potentially suitable update frameworks and evaluate them based on automotive requirements. A focus is on a holistic view of requirements, considering safety, security, and availability. 相似文献
4.
《工程(英文)》2020,6(12):1423-1431
China’s past economic growth has substantially relied on fossil fuels, causing serious air pollution issues. Decoupling economic growth and pollution has become the focus in developing ecological civilization in China. We have analyzed the three-decade progress of air pollution controls in China, highlighting a strategic transformation from emission control toward air quality management. Emission control of sulfur dioxide (SO2) resolved the deteriorating acid rain issue in China in 2007. Since 2013, control actions on multiple precursors and sectors have targeted the reduction of the concentration of fine particulate matter (PM2.5), marking a transition to an air-quality-oriented strategy. Increasing ozone (O3) pollution further requires O3 and PM2.5 integrated control strategies with an emphasis on their complex photochemical interactions. Fundamental improvement of air quality in China, as a key indicator for the success of ecological civilization construction, demands the deep de-carbonization of China’s energy system as well as more synergistic pathways to address air pollution and global climate change simultaneously. 相似文献
5.
Recently, the Tactile Internet (TI) becomes a new era of the Internet. The TI provides ultra-reliable, ultra-responsive and intelligent network connectivity for delivering real-time control and physical haptic experiences from a remote location. The TI provides a different feeling to human–machine interaction by implementing the real-time interactive systems. In this review article, we discuss a generalized authentication model which can be used to perform authentication procedure among different communicating parties in order to secure remote surgery in the TI environment. By using the proposed authentication model, an authentication protocol can be designed so that an authenticated surgeon can use the robot/robotic arms to perform the surgery securely as well as remotely. Since the application is very critical, the important instructions provided by the surgeon to the robot/robotic arms must not be leaked in between the communication during the surgical procedure. To deal with this emerging research area, a secure mutual user authentication mechanism should be provided between a remote surgeon and the robot/robotic arms so that they can communicate securely using the established session key among them. Further, several security issues and challenges for such kind of communication are also discussed in this article. Finally, we discuss few points that need to be considered as future research works that are related to authentication for securing remote surgery in the TI environment. 相似文献
6.
本文以安东尼·高迪在古埃尔公园与古埃尔礼拜堂中处理场地的方式为出发点,通过对当代加泰罗尼亚建筑师爱德华·布鲁、恩瑞克·米拉莱斯、卡洛斯·费拉特尔、约瑟夫·里纳斯等人作品的分析,引出加泰罗尼亚建筑师在如何处理建筑与场地环境方式上的一种共识性态度,即在加泰罗尼亚,建筑师多以场地信息作为关键因素切入设计,最终的作品同场地和谐共融。这种不同于元素借用或者是材料肌理延续的方式在文章中被定义称为"地景式建筑"。 相似文献
7.
Daodi Flood Land, located in Mentougou District of Beijing, is a relatively separate flood land in the lower reaches and on the east of Yonding River. This largest landscape character area in the west of Beijing along the river illustrates the history of human–water interaction and discloses the trends and problems of rural urbanization. Focusing on Daodi Flood Land, this paper expands the research on adaptation by introducing basic concepts and research framework, and reviews the research trends from spatial, temporal, and participant aspects. Considering the typical characters of the study area, this research employed participatory approaches, such as mapping and problem and solution trees, due to the lack of continuous and accurate data. Basing on literature review and field investigation on issues of floods, agricultural irrigation, and water resource utilization, water adaptive development visions for the study area were proposed from perspectives of landscape and culture. Finally, the paper further analyzes the structural relations between adaptation problems, natural and social systems, passive and active adaptations, and planned and unplanned adaptations, with the aim to provide reference for relevant studies and applications of adaptation approaches in other cases. 相似文献
8.
Thomas RAINER 《景观设计学(英文)》2021,9(1):112
The ability of landscape architectural projects to mitigate the worst effects of climate change will depend upon designed ecological systems. These systems will be built with plants. Despite the recognition of ecology as an essential driver of landscapes, the professionals of landscape architecture too often lack the knowledge and practical skills to create robust vegetative systems. New approaches and tools are required. This article outlines principles and methods for designing biodiverse plant systems for urban sites. Planting methods that increase species richness, functional diversity, and spatial complexity are emphasized as a way of developing more resilient plantings. Selecting species with similar evolutionary adaptions to stress, disturbance, and competition—as well as creating multi-layered compositions of diverse plant morphologies—allows designers to create compatible, long-lived plant mixes. To balance the increased visual complexity of diverse plant mixes, the article explores design techniques to make plantings more appealing to the public. The strategies explored here are based on the projects, experience, and research of Phyto Studio, a Washington, D.C. based studio. The methods build on work described in the author’s book, Planting in a Post-Wild World, an exploration of how to create designed plant communities. 相似文献
9.
10.
Kongjian YU 《景观设计学(英文)》2021,9(3):4
Large rivers with beautiful landscapes were dreamlands to the author. However, every time upon his arrival to riversides, he was shocked for the heavily polluted rivers that are dirty, messy, and smelling. Engineered dikes and dams made of concrete and steels for a greater height and hardness are built by cities along rivers. As more highways and railways built along rivers, vehicles run at a faster speed, scaring any life who wants to or has to access the water. Most of the tributaries are no longer free flow but end up as hard ditches and the water is polluted heavily. Forests and wetlands are being damaged and eroded. All of these are resulted from humans’ material desires and lack of respect for nature. Nevertheless, ecological civilization may encourage people to appreciate the beauty of nature and get a thorough understanding on river ecosystems and their services, accompanied by systematic planning and implementation of territorial ecological restoration. Moreover, laws and regulations on large river management should be put in place, and efforts should be made to break the worship of grey engineering approaches to flood control. It is expected that nature-based ecological approaches for a better resilience and sustainability in flood management can be more effective to ensure water safety. 相似文献