全文获取类型
收费全文 | 36963篇 |
免费 | 2060篇 |
国内免费 | 913篇 |
专业分类
电工技术 | 1188篇 |
技术理论 | 2篇 |
综合类 | 1490篇 |
化学工业 | 5682篇 |
金属工艺 | 1174篇 |
机械仪表 | 1328篇 |
建筑科学 | 1946篇 |
矿业工程 | 524篇 |
能源动力 | 758篇 |
轻工业 | 4101篇 |
水利工程 | 507篇 |
石油天然气 | 792篇 |
武器工业 | 131篇 |
无线电 | 3522篇 |
一般工业技术 | 4600篇 |
冶金工业 | 7039篇 |
原子能技术 | 474篇 |
自动化技术 | 4678篇 |
出版年
2024年 | 91篇 |
2023年 | 299篇 |
2022年 | 635篇 |
2021年 | 822篇 |
2020年 | 592篇 |
2019年 | 626篇 |
2018年 | 718篇 |
2017年 | 776篇 |
2016年 | 797篇 |
2015年 | 852篇 |
2014年 | 1267篇 |
2013年 | 1908篇 |
2012年 | 1812篇 |
2011年 | 2128篇 |
2010年 | 1816篇 |
2009年 | 1752篇 |
2008年 | 1855篇 |
2007年 | 1778篇 |
2006年 | 1555篇 |
2005年 | 1400篇 |
2004年 | 1131篇 |
2003年 | 1025篇 |
2002年 | 1020篇 |
2001年 | 873篇 |
2000年 | 772篇 |
1999年 | 820篇 |
1998年 | 2243篇 |
1997年 | 1435篇 |
1996年 | 1058篇 |
1995年 | 725篇 |
1994年 | 626篇 |
1993年 | 602篇 |
1992年 | 306篇 |
1991年 | 277篇 |
1990年 | 268篇 |
1989年 | 260篇 |
1988年 | 260篇 |
1987年 | 185篇 |
1986年 | 200篇 |
1985年 | 252篇 |
1984年 | 162篇 |
1983年 | 135篇 |
1982年 | 123篇 |
1981年 | 152篇 |
1980年 | 147篇 |
1979年 | 139篇 |
1978年 | 91篇 |
1977年 | 194篇 |
1976年 | 321篇 |
1975年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Fan Deng-Ping Huang Ziling Zheng Peng Liu Hong Qin Xuebin Van Gool Luc 《国际自动化与计算杂志》2022,19(4):257-287
Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a... 相似文献
2.
Junjie Li Mei Liang Wanjing Cheng Shuhao Wang 《International Journal of Hydrogen Energy》2021,46(14):9553-9566
Electric vehicles (EVs) are considered a promising alternative to conventional vehicles (CVs) to alleviate the oil crisis and reduce urban air pollution and carbon emissions. Consumers usually focus on the tangible cost when choosing an EV or CV but overlook the time cost for restricting purchase or driving and the environmental cost from gas emissions, falling to have a comprehensive understanding of the economic competitiveness of CVs and EVs. In this study, a life cycle cost model for vehicles is conducted to express traffic and environmental policies in monetary terms, which are called intangible cost and external cost, respectively. Battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and CVs are compared in four first-tier, four new first-tier, and 4 s-tier and below cities in China. The comparison shows that BEVs and FCEVs in most cities are incomparable with CVs in terms of tangible cost. However, the prominent traffic and environmental policies in first-tier cities, especially in Beijing and Shanghai, greatly increase the intangible and external costs of CVs, making consumers more inclined to purchase BEVs and FCEVs. The main policy benefits of BEVs and FCEVs come from three aspects: government subsidies, purchase and driving restrictions, and environmental taxes. With the predictable reduction in government subsidies, traffic and environmental policies present important factors influencing the competitiveness of BEVs and FCEVs. In first-tier cities, BEVs and FCEVs already have a competitive foundation for large-scale promotion. In new first-tier and second-tier and below cities, stricter traffic and environmental policies need to be formulated to offset the negative impact of the reduction in government subsidies on the competitiveness of BEVs and FCEVs. Additionally, a sensitivity analysis reveals that increasing the mileage and reducing fuel prices can significantly improve the competitiveness of BEVs and FCEVs, respectively. 相似文献
3.
4.
5.
Stefanie Vanbecelaere Katrien Van den Berghe Frederik Cornillie Delphine Sasanguie Bert Reynvoet Fien Depaepe 《Journal of Computer Assisted Learning》2020,36(4):502-513
For the training of academic skills, digital educational games with integrated adaptivity are promising. Adaptive games are considered superior to non-adaptive games, because they constantly assess children's performance, and accordingly adapt the difficulty of the tasks corresponding to the children's individual level. However, empirical evidence with regard to the effectivity of adaptive compared to non-adaptive games is limited. A study was conducted with 191 children from the third year of Kinder garten who were enrolled in one of three conditions, that is, playing an adaptive version of the reading game (RG), a non-adaptive version of the RG or training with pen-and-paper exercises. In all three conditions, children trained emergent reading (phonological awareness and letter knowledge) once a week for 30 min over a period of 5 weeks. Children's performance on cognitive (phonological awareness, letter knowledge, reading fluency) and non-cognitive (motivation, self-concept) factors was assessed. Results revealed a significant improvement in phonological awareness and letter knowledge in all conditions. However, no differences between the conditions were observed with respect to children's improvement on phonological awareness and letter knowledge or on their post-test scores for reading fluency. With regard to motivation and self-concept, again, no differences in these non-cognitive factors were observed across conditions. 相似文献
6.
7.
8.
9.
设备综合管理工作始终贯穿在项目建设整个过程中.从项目立项审查、基础设计审查、设备订货前的技术把关,到工程施工环节的专业技术检查,再到项目中交、联动试车、投料试车,处处可见设备综合管理的内容.本文梳理出设备综合管理的主要节点内容、现状和存在的问题,针对镇海基地项目群的建设,就如何发挥设备专业化的优势、如何对设备综合管理工作进行创新、如何优化工作流程进行了探索.旨在通过设备综合管理工作的统筹和协调,将专业化优势形成合力,更高质量、更高效率地为项目建设服务. 相似文献
10.
Anh Tuan Thanh Pham Oanh Kieu Truong Le Dung Van Hoang Truong Huu Nguyen Trang Huyen Cao Pham Phuong Thanh Ngoc Vo Thang Bach Phan Vinh Cao Tran 《Journal of the European Ceramic Society》2021,41(6):3493-3500
Structure modification has been found to tune significantly the transparent-conducting performance, especially mobility and conductivity of hydrogenated Ga-doped ZnO (HGZO) films. The strong correlation between film thickness and mobility of the films is revealed. The mobility increases quickly with increasing the thickness from 350 to 900 nm, and then tends to be saturated at further thicknesses. A higher mobility than 50 cm2/Vs can be achieved, which is an extra-high value for polycrystalline ZnO films deposited by using the sputtering technique. The thickness-dependent mobility originates from scatterings on grain boundaries and dislocation-induced defects controlled by thin-film growth. Based on the Volmer-Weber model, an expansion model is built up to describe the thickness-dependent crystal growth of the HGZO films, especially at the thick films. As a result, the 800 nm-thick HGZO film obtains the highest performance with high mobility of 51.5 cm2/Vs, low resistivity of 5.3 × 10?4 Ωcm, and good transmittance of 83.3 %. 相似文献