全文获取类型
收费全文 | 6599篇 |
免费 | 474篇 |
国内免费 | 113篇 |
专业分类
电工技术 | 253篇 |
综合类 | 202篇 |
化学工业 | 1217篇 |
金属工艺 | 209篇 |
机械仪表 | 203篇 |
建筑科学 | 391篇 |
矿业工程 | 57篇 |
能源动力 | 318篇 |
轻工业 | 532篇 |
水利工程 | 98篇 |
石油天然气 | 179篇 |
武器工业 | 4篇 |
无线电 | 708篇 |
一般工业技术 | 940篇 |
冶金工业 | 659篇 |
原子能技术 | 24篇 |
自动化技术 | 1192篇 |
出版年
2024年 | 17篇 |
2023年 | 100篇 |
2022年 | 172篇 |
2021年 | 228篇 |
2020年 | 178篇 |
2019年 | 180篇 |
2018年 | 237篇 |
2017年 | 226篇 |
2016年 | 261篇 |
2015年 | 230篇 |
2014年 | 259篇 |
2013年 | 482篇 |
2012年 | 368篇 |
2011年 | 456篇 |
2010年 | 368篇 |
2009年 | 379篇 |
2008年 | 318篇 |
2007年 | 275篇 |
2006年 | 284篇 |
2005年 | 223篇 |
2004年 | 155篇 |
2003年 | 165篇 |
2002年 | 214篇 |
2001年 | 151篇 |
2000年 | 124篇 |
1999年 | 73篇 |
1998年 | 139篇 |
1997年 | 102篇 |
1996年 | 85篇 |
1995年 | 79篇 |
1994年 | 84篇 |
1993年 | 62篇 |
1992年 | 32篇 |
1991年 | 22篇 |
1990年 | 32篇 |
1989年 | 36篇 |
1988年 | 29篇 |
1987年 | 29篇 |
1986年 | 21篇 |
1985年 | 28篇 |
1984年 | 40篇 |
1983年 | 28篇 |
1982年 | 19篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 16篇 |
1978年 | 13篇 |
1977年 | 20篇 |
1976年 | 26篇 |
1973年 | 17篇 |
排序方式: 共有7186条查询结果,搜索用时 15 毫秒
71.
72.
Farid Touati Adel Ben Mnaouer Ochirkhand Erdene‐Ochir Waiser Mehmood Ammad Hassan Brahim Gaabab 《Wireless Communications and Mobile Computing》2016,16(10):1271-1281
Technology has revolutionized medical practices by enabling more convenient and non‐intrusive monitoring of patient's health, leading to next generation ubiquitous healthcare (u‐healthcare). The exploitation of the Internet protocol version 6 addressing space along with the miniaturization of electronic devices has fostered providing interoperability and connectivity of wearable sensor devices in wireless body area networks to the Internet of Things. In this paper, we propose to integrate the IPv6 over low power wireless personal area network (6LoWPAN) to the u‐healthcare monitoring system architecture. The main objective is to study the feasibility of the 6LoWPAN‐enabled platform in real‐world scenarios dealing with medical data. The performance evaluation of this platform is carried out initially through simulations using OMNet++ and then supported by an experimental study using sensor motes and a customized micro‐computing unit. Performance metrics such as throughput, end‐to‐end delay, packet error rate, and energy consumption are investigated under acute health conditions, where patient's health information has to be sent continuously and at maximum rate to the care provider. The obtained results show that the proposed 6LoWPAN solution fulfills the main quality of service requirements of u‐healthcare applications. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
73.
Wei Qin Dan Ding Jianzhao Liu Wang Zhang Yuan Yong Hu Bin Liu Ben Zhong Tang 《Advanced functional materials》2012,22(4):771-779
Light emission of 2‐(2,6‐bis((E)‐4‐(diphenylamino)styryl)‐4H‐pyran‐4‐ylidene)malononitrile (TPA‐DCM) is weakened by aggregate formation. Attaching tetraphenylethene (TPE) units as terminals to TPA‐DCM dramatically changes its emission behavior: the resulting fluorogen, 2‐(2,6‐bis((E)‐4‐(phenyl(4′‐(1,2,2‐triphenylvinyl)‐[1,1′‐biphenyl]‐4‐yl)amino)styryl)‐4H‐pyran‐4‐ylidene)malononitrile (TPE‐TPA‐DCM), is more emissive in the aggregate state, showing the novel phenomenon of aggregation‐induced emission (AIE). Formulation of TPE‐TPA‐DCM using bovine serum albumin (BSA) as the polymer matrix yields uniformly sized protein nanoparticles (NPs) with high brightness and low cytotoxicity. Applications of the fluorogen‐loaded BSA NPs for in vitro and in vivo far‐red/near‐infrared (FR/NIR) bioimaging are successfully demonstrated using MCF‐7 breast‐cancer cells and a murine hepatoma‐22 (H22)‐tumor‐bearing mouse model, respectively. The AIE‐active fluorogen‐loaded BSA NPs show an excellent cancer cell uptake and a prominent tumor‐targeting ability in vivo due to the enhanced permeability and retention effect. 相似文献
74.
Cardiovascular responses and mammary substrate uptake in Jersey cows treated with pituitary-derived growth hormone during late lactation 总被引:2,自引:0,他引:2
F M Fullerton I R Fleet R B Heap I C Hart T Ben Mepham 《The Journal of dairy research》1989,56(1):27-35
Pituitary-derived bovine growth hormone (bGH) was administered to Jersey cows during late lactation for 7 d. Milk yield increased significantly during treatment and by a maximum of 49.6% on d 7. The magnitude of the increase was similar to that of mammary plasma flow (47.8 +/- 18.3%) over the same period. By 15-21 d after treatment, both variables had returned to pretreatment values. With respect to milk composition, bGH had negligible effect on lactose and fat concentrations but there were significant decreases in protein, sodium and chloride. Arterial plasma concentrations of bGH increased substantially during treatment, but the associated rise in insulin was not statistically significant. Haematocrit decreased significantly, the lowest value being recorded 3 d after bGH treatment ceased. Mammary respiratory quotient fell progressively after the start of bGH treatment and reached the lowest recorded value 3 d after treatment ceased (62.2 +/- 7.3% of pretreatment value). Glucose and acetate uptake by the mammary gland increased significantly during treatment, increase in glucose uptake being due both to a greater arterio-venous difference and to mammary plasma flow. There was strong evidence that the acute response in increased milk yield was associated with multiple effects in terms of mammary plasma flow and metabolism, as well as haematocrit changes indicative of increased plasma volume. 相似文献
75.
Zouhour Ben Ahmed 《Analog Integrated Circuits and Signal Processing》2018,96(2):261-268
Aligned with the recent revolution of smart cities concept, a lot of work has been done to support the education process in direct or indirect way. In countries like Lebanon, in which the choice of school does not depend on the residence location, parents are becoming more and more selective in the quality of schools they are choosing for their children. This fact may lead parents to choose a modern and good school even if it is far from their residence. On the other hand, and even if the school was close enough, the traffic congestion would make the on-feet journey of the kid to the school very risky. Driving children to school is a solution. However, it consumes a lot of time and effort each day in the morning and the afternoon. Hence, school buses are commonly used by all schools to take the student from and to his home. Nevertheless, waiting the bus each day to arrive is an exhausting and a time-wasting mission. In this paper we present a smart transportation system for school buses that helps in saving parents’ time, by avoiding waiting school buses in the morning and then in the afternoon to return kids back, especially with the increasing traffic jams at these hours. The proposed mobile and web application is designed to help parents, school and the bus to communicate automatically and easily via the application in order to detect kids’ arrival time. The bus application side will notify parents few minutes before its approaching to their homes. Furthermore, the system will allow parents to inform the school and hence the bus application side about the absence of their kid. The system has been efficiently and dynamically designed and implemented so it can be hosted and used by any school administration without the need to any major modifications. It has been tested on a summer school to prove its efficiency and marked an important positive feedback from the school and the parents’ sides. 相似文献
76.
With rapid developments of digital photography and social networks,users of photo-sharing-supported social networking applications can easily forward photos across different social networks at the cost of their growing privacy concerns.To address this problem,a privacy-preserving photo sharing framework was proposed,which could apply to extended control and privacy invasion tracing.In extended control scheme,the following users on a dissemination chain was restrained by each user’s privacy policy.Then several privacy areas of photos were encrypted and the access control polices were bound to the uploaded photos,so that any privacy areas on the photos could be hidden away from unwanted viewers even across different social networks.On this basis,the behaviors of users were record by tracing scheme of privacy invasion,the integrality of records was protected by using nested signature algorithm.The correctness,security and performance of overhead of the scheme are then thoroughly analyzed and evaluated via detailed simulations. 相似文献
77.
Chengcheng Zhou Wenhan Xu Pengbo Zhang Meijuan Jiang Yuncong Chen Ryan T. K. Kwok Michelle M. S. Lee Guogang Shan Ruilian Qi Xin Zhou Jacky W. Y. Lam Shu Wang Ben Zhong Tang 《Advanced functional materials》2019,29(4)
Lacking rapid and reliable pathogen diagnostic platforms, inadequate or delayed antimicrobial therapy could be made, which greatly threatens human life and accelerates the emergence of antibiotic‐resistant pathogens. In this contribution, a series of simple and reliable sensor arrays based on tetraphenylethylene (TPE) derivatives are successfully developed for detection and discrimination of pathogens. Each sensor array consists of three TPE‐based aggregation‐induced emission luminogens (AIEgens) that bear cationic ammonium group and different hydrophobic substitutions, providing tunable logP (n‐octanol/water partition coefficient) values to enable the different multivalent interactions with pathogens. On the basis of the distinctive fluorescence response produced by the diverse interaction of AIEgens with pathogens, these sensor arrays can identify different kinds of pathogens, even normal and drug‐resistant bacteria, with nearly 100% accuracy. Furthermore, blends of pathogens can also be identified accurately. The sensor arrays exhibit rapid response (about 0.5 h), high‐throughput, and easy‐to‐operate without washing steps. 相似文献
78.
Nan Song Zhijun Zhang Peiying Liu Dihua Dai Chao Chen Youmei Li Lei Wang Ting Han Ying-Wei Yang Dong Wang Ben Zhong Tang 《Advanced functional materials》2021,31(21):2009924
Supramolecular approaches have opened up vast possibilities to construct versatile materials, especially those with stimuli-responsiveness and integrated functionalities of multi-modal diagnosis and synergistic therapeutics. In this study, a hybrid theranostic nanosystem named TTPY-Py⊂CP5@AuNR is constructed via facile host–guest interactions, where TTPY-Py is a photosensitizer with aggregation-induced emission and CP5@AuNR represents the carboxylatopillar[5]arene (CP5)-modified Au nanorods. TTPY-Py⊂CP5@AuNR integrates the respective advantages of TTPY-Py and CP5@AuNR such as the high performance of reactive oxygen species generation and photothermal conversion, and meanwhile shows fluorescence responses to both temperature and pH stimuli. The successful modification of CP5 macrocycles on AuNRs surfaces can eliminate the cytotoxicity of AuNRs and enable them to serve as the nanocarrier of TTPY-Py for further theranostic applications. Significantly, in vitro and in vivo evaluations demonstrate that this supramolecular nanotheranostic system possesses multiple modalities including intensive fluorescence imaging (FLI), photoacoustic imaging (PAI), efficient photodynamic therapy (PDT), and photothermal therapy (PTT), indicating its great potential for FLI-PAI imaging-guided synergistic PDT-PTT therapy. Moreover, TTPY-Py can be released upon activation by the acidic environment of lysosomes and then specifically light up mitochondria. This study demonstrates a new strategy for the design of versatile nanotheranostics for accurate tumor imaging and cancer therapies. 相似文献
79.
温度是影响半导体激光器(LD)寿命和输出特性的重要因素之一。为保证LD输出稳定的激光模式和功率,采用以ADC和DAC集成的微处理器芯片C8051F350和具有双极性输出电流的TEC驱动芯片MAX1968为控制核心,以积分分离和变速积分增量式相结合的数字PID算法为运算程序的自动温度控制系统(ATC)控制TEC驱动电流的方向和大小,实现对LD的加热或制冷,使其工作在恒定温度。实验证明,应用该系统,LD在0℃~40℃环境温度范围内能很快稳定在设定温度,且其不确定度为±0.03℃。 相似文献
80.
Ilya Chukhman Yang Jiao Haifa Ben Salem Shuvra S. Bhattacharyya 《Journal of Signal Processing Systems》2016,84(3):383-397
Dataflow modeling offers a myriad of tools for designing and optimizing signal processing systems. A designer is able to take advantage of dataflow properties to effectively tune the system in connection with functionality and different performance metrics. However, a disparity in the specification of dataflow properties and the final implementation can lead to incorrect behavior that is difficult to detect. This motivates the problem of ensuring consistency between dataflow properties that are declared or otherwise assumed as part of dataflow-based application models, and the dataflow behavior that is exhibited by implementations that are derived from the models. In this paper, we address this problem by introducing a novel dataflow validation framework (DVF) that is able to identify disparities between an application’s formal dataflow representation and its implementation. DVF works by instrumenting the implementation of an application and monitoring the instrumentation data as the application executes. This monitoring process is streamlined so that DVF achieves validation without major overhead. We demonstrate the utility of our DVF through design and implementation case studies involving an automatic speech recognition application, a JPEG encoder, and an acoustic tracking application. 相似文献