全文获取类型
收费全文 | 15769篇 |
免费 | 1334篇 |
国内免费 | 630篇 |
专业分类
电工技术 | 878篇 |
技术理论 | 3篇 |
综合类 | 900篇 |
化学工业 | 2784篇 |
金属工艺 | 979篇 |
机械仪表 | 1029篇 |
建筑科学 | 1196篇 |
矿业工程 | 536篇 |
能源动力 | 443篇 |
轻工业 | 903篇 |
水利工程 | 253篇 |
石油天然气 | 1244篇 |
武器工业 | 104篇 |
无线电 | 1734篇 |
一般工业技术 | 1943篇 |
冶金工业 | 865篇 |
原子能技术 | 153篇 |
自动化技术 | 1786篇 |
出版年
2024年 | 85篇 |
2023年 | 316篇 |
2022年 | 510篇 |
2021年 | 700篇 |
2020年 | 549篇 |
2019年 | 457篇 |
2018年 | 531篇 |
2017年 | 530篇 |
2016年 | 451篇 |
2015年 | 629篇 |
2014年 | 798篇 |
2013年 | 839篇 |
2012年 | 953篇 |
2011年 | 1039篇 |
2010年 | 895篇 |
2009年 | 871篇 |
2008年 | 899篇 |
2007年 | 779篇 |
2006年 | 803篇 |
2005年 | 664篇 |
2004年 | 551篇 |
2003年 | 456篇 |
2002年 | 455篇 |
2001年 | 381篇 |
2000年 | 362篇 |
1999年 | 425篇 |
1998年 | 312篇 |
1997年 | 299篇 |
1996年 | 254篇 |
1995年 | 221篇 |
1994年 | 176篇 |
1993年 | 122篇 |
1992年 | 111篇 |
1991年 | 70篇 |
1990年 | 64篇 |
1989年 | 49篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1986年 | 19篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
81.
82.
83.
作为"一卡通"的一个子系统,门禁系统早已超越了单纯的门道及钥匙管理,它已经逐渐发展成为一套完整的出入管理系统.本文对钢铁冶金企业中应用较为广泛的门禁一卡通系统的功能进行了需求分析,给出了系统的网络结构设计,并详细介绍该系统的各项功能以及可靠性及安全防护措施,对系统特点进行了详细描述. 相似文献
84.
85.
Field‐Induced n‐Doping of Black Phosphorus for CMOS Compatible 2D Logic Electronics with High Electron Mobility 下载免费PDF全文
Yijun Xu Jian Yuan Kai Zhang Yuan Hou Qiu Sun Yingming Yao Shaojuan Li Qiaoliang Bao Han Zhang Yuegang Zhang 《Advanced functional materials》2017,27(38)
Black phosphorus (BP) has been considered as a promising two‐dimensional (2D) semiconductor beyond graphene owning to its tunable direct bandgap and high carrier mobility. However, the hole‐transport‐dominated characteristic limits the application of BP in versatile electronics. Here, we report a stable and complementary metal oxide semiconductor (COMS) compatible electron doping method for BP, which is realized with the strong field‐induced effect from the K+ center of the silicon nitride (SixNy). An obvious change from pristine p‐type BP to n type is observed after the deposit of the SixNy on the BP surface. This electron doping can be kept stable for over 1 month and capable of improving the electron mobility of BP towards as high as ~176 cm2 V–1 s–1. Moreover, high‐performance in‐plane BP p‐n diode and further logic inverter were realized by utilizing the n‐doping approach. The BP p‐n diode exhibits a high rectifying ratio of ~104. And, a successful transfer of the output voltage from “High” to “Low” with very few voltage loss at various working frequencies were also demonstrated with the constructed BP inverter. Our findings paves the way for the success of COMS compatible technique for BP‐based nanoelectronics. 相似文献
86.
Using Bulk Heterojunctions and Selective Electron Trapping to Enhance the Responsivity of Perovskite–Graphene Photodetectors 下载免费PDF全文
Liang Qin Liping Wu Bhupal Kattel Chunhai Li Yong Zhang Yanbing Hou Judy Wu Wai‐Lun Chan 《Advanced functional materials》2017,27(47)
Graphene field effect transistor sensitized by a layer of semiconductor (sensitizer/GFET) is a device structure that is investigated extensively for ultrasensitive photodetection. Among others, organometallic perovskite semiconductor sensitizer has the advantages of long carrier lifetime and solution processable. A further step to improve the responsivity is to design a structure that can promote electron–hole separation and selective carrier trapping in the sensitizer. Here, the use of a hybrid perovskite–organic bulk heterojunction (BHJ) as the light sensitizer to achieve this goal is demonstrated. Our spectroscopy and device measurements show that the CH3NH3PbI3–PCBM BHJ/GFET device has improved charge separation yield and carrier lifetime as compared to a reference device with a CH3NH3PbI3 sensitizer only. The key to these enhancement is the presence of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), which acts as charge separation and electron trapping sites, resulting in a 30‐fold increase in the photoresponsivity. This work shows that the use of a small amount of electron or hole acceptors in the sensitizer layer can be an effective strategy for improving and tuning the photoresponsivity of sensitizer/GFET photodetectors. 相似文献
87.
Cancer Therapy: Photo‐Induced Charge‐Variable Conjugated Polyelectrolyte Brushes Encapsulating Upconversion Nanoparticles for Promoted siRNA Release and Collaborative Photodynamic Therapy under NIR Light Irradiation (Adv. Funct. Mater. 44/2017) 下载免费PDF全文
88.
Tan Zhang Zhenwei Hou Johnson R.W. Del Castillo L. Moussessian A. Greenwell R. Blalock B.J. 《Electronics Packaging Manufacturing, IEEE Transactions on》2009,32(4):291-300
Silicon thinned to 50 mum and less is flexible allowing the fabrication of flexible and conformable electronics. Two techniques have been developed to achieve this goal using thinned die: die flip chip bonded onto flexible substrates [polyimide and liquid crystal polymer (LCP)] and die flip chip laminated onto LCP films. A key to achieving each of these techniques is the thinning of die to a thickness of 50 mum or thinner. Conventional grinding and polishing can be used to thin to 50 mum. At 50 mum, the active die becomes flexible and must be handled by temporarily bonding it to a holder die for assembly. Both reflow solder and thermocompression assembly methods are used. In the case of solder assembly, underfill is used to reinforce the solder joints. With thermocompression bonding of the die to an LCP substrate, the LCP adheres to the die surface, eliminating the need for underfill. 相似文献
89.
Using the multiple-parameter Monte Carlo method, the effectiveness of the dual threshold voltage technique (DTV) in low power domino logic design is analyzed. Simulation results indicate that under significant temperature and process fluctuations, DTV is still highly effective in reducing the total leakage and active power consumption for domino gates with speed loss. Also, regarding power and delay characteristics, different structure domino gates with DTV have different robustness against temperature and process fluctuation. 相似文献
90.
区分服务(Diffsevr)通过服务分级定义了流量的逐跳行为(PHB);流量工程(Traffic Engnineering)实现转发路径的优化。感知区分服务的MPLS流量工程(Diffsevr-aware MPLS Traffic Engnineering,简称DS-TE)将MPLS的区分服务与流量工程结合在一起,使其能够感知彼此的存在。DS-TE提出了基于类的资源分配思想,可以根据业务的类型,细粒度地建立交换路径,进一步保证了QoS。 相似文献