全文获取类型
收费全文 | 6321篇 |
免费 | 557篇 |
国内免费 | 188篇 |
专业分类
电工技术 | 115篇 |
综合类 | 111篇 |
化学工业 | 1386篇 |
金属工艺 | 120篇 |
机械仪表 | 327篇 |
建筑科学 | 180篇 |
矿业工程 | 28篇 |
能源动力 | 344篇 |
轻工业 | 792篇 |
水利工程 | 82篇 |
石油天然气 | 208篇 |
武器工业 | 8篇 |
无线电 | 816篇 |
一般工业技术 | 1287篇 |
冶金工业 | 109篇 |
原子能技术 | 60篇 |
自动化技术 | 1093篇 |
出版年
2024年 | 46篇 |
2023年 | 222篇 |
2022年 | 511篇 |
2021年 | 807篇 |
2020年 | 494篇 |
2019年 | 540篇 |
2018年 | 490篇 |
2017年 | 414篇 |
2016年 | 419篇 |
2015年 | 288篇 |
2014年 | 338篇 |
2013年 | 445篇 |
2012年 | 303篇 |
2011年 | 368篇 |
2010年 | 209篇 |
2009年 | 201篇 |
2008年 | 148篇 |
2007年 | 148篇 |
2006年 | 92篇 |
2005年 | 70篇 |
2004年 | 70篇 |
2003年 | 48篇 |
2002年 | 42篇 |
2001年 | 29篇 |
2000年 | 46篇 |
1999年 | 36篇 |
1998年 | 27篇 |
1997年 | 20篇 |
1996年 | 23篇 |
1995年 | 23篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 6篇 |
1989年 | 15篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1969年 | 1篇 |
1961年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有7066条查询结果,搜索用时 15 毫秒
71.
吸波体是一种带有损耗特性的周期结构,能够吸收电磁波,将电磁能转化为热能,降低反射的电磁波能量。随着应用场景的特殊化,吸波体朝着特殊领域、特定功能、更具针对性的方向发展。由于各类含有光学窗口的应用环境对抗电磁干扰需求的不断提高,吸波体光学透明化成为研究的重点方向。为了对透明吸波体的发展状况有系统的认识,文章以制造材料为脉络梳理了近年来可见光透明吸波体的研究现状,包括氧化铟锡(ITO)、金属网栅、石墨烯等,综述了以它们为材料制备的透明吸波体优缺点以及发展趋势,最后对透明吸波体的未来发展进行了展望。 相似文献
72.
Ikram Muhammad Jawad Saleh Mostafa Elsayed Al-Hashimi Muhammad Abdulhamid Abulnaja Osama Ahmed 《The Journal of supercomputing》2022,78(13):14919-14939
The Journal of Supercomputing - Power consumption is likely to remain a significant concern for exascale performance in the foreseeable future. In addition, graphics processing units (GPUs) have... 相似文献
73.
Raja Muhammad Asif Zahoor Naz Hira Shoaib Muhammad Mehmood Ammara 《Neural computing & applications》2022,34(7):5771-5790
Neural Computing and Applications - In the present study, a novel application of backpropagated neurocomputing heuristics (BNCH) is presented for epidemic virus model that portrays the Stuxnet... 相似文献
74.
Faisal Bahadur Arif Iqbal Umar Insaf Ullah Fahad Algarni Muhammad Asghar Khan 《计算机系统科学与工程》2022,42(2):589-604
Scalability is one of the most important quality attribute of software-intensive systems, because it maintains an effective performance parallel to the large fluctuating and sometimes unpredictable workload. In order to achieve scalability, thread pool system (TPS) (which is also known as executor service) has been used extensively as a middleware service in software-intensive systems. TPS optimization is a challenging problem that determines the optimal size of thread pool dynamically on runtime. In case of distributed-TPS (DTPS), another issue is the load balancing b/w available set of TPSs running at backend servers. Existing DTPSs are overloaded either due to an inappropriate TPS optimization strategy at backend servers or improper load balancing scheme that cannot quickly recover an overload. Consequently, the performance of software-intensive system is suffered. Thus, in this paper, we propose a new DTPS that follows the collaborative round robin load balancing that has the effect of a double-edge sword. On the one hand, it effectively performs the load balancing (in case of overload situation) among available TPSs by a fast overload recovery procedure that decelerates the load on the overloaded TPSs up to their capacities and shifts the remaining load towards other gracefully running TPSs. And on the other hand, its robust load deceleration technique which is applied to an overloaded TPS sets an appropriate upper bound of thread pool size, because the pool size in each TPS is kept equal to the request rate on it, hence dynamically optimizes TPS. We evaluated the results of the proposed system against state of the art DTPSs by a client-server based simulator and found that our system outperformed by sustaining smaller response times. 相似文献
75.
The Journal of Supercomputing - The central cloud facilities based on virtual machines offer many benefits to reduce the scheduling costs and improve service availability and accessibility. The... 相似文献
76.
Muhammad Rashid Zafar Abbas M. Yaseen Qadeer Afzal Asif Mahmood Shahid M. Ramay 《Journal of Superconductivity and Novel Magnetism》2017,30(11):3129-3136
The full potential linearized augmented plane wave method of density functional theory has been used to investigate the structural, electronic, magnetic and thermoelectric properties of cubic perovskites BaVO3 and LaVO3. The ferromagnetic ground state has been found to be stable by comparing the total energies of non-spin-polarized and spin-polarized calculations performed for optimized unit cells. For both compounds, the bond length and tolerance factor are also measured. From the band structures and density of states plots, it is found that both compounds are half-metallic. We found that the presence of V at the octahedral site of these perovskites develops exchange splitting through p-d hybridization, which results in a stable ferromagnetic state. The observed exchange splitting is further clarified from the magnetic moment, charge and spin of the anion and cations. Finally, we also presented the calculated thermoelectric properties of these materials, which show that half-metallic BaVO3 and LaVO3 materials are potential contenders for thermoelectric applications. 相似文献
77.
Insights into the Influence of Work Functions of Cathodes on Efficiencies of Perovskite Solar Cells 下载免费PDF全文
Shizhong Yue Shudi Lu Kuankuan Ren Kong Liu Muhammad Azam Dawei Cao Zhijie Wang Yong Lei Shengchun Qu Zhanguo Wang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(19)
Though various efforts on modification of electrodes are still undertaken to improve the efficiency of perovskite solar cells, attributing to the large scope of these methods, it is of significance to unveil the working principle systematically. Herein, inverted perovskite solar cells based on indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/CH3NH3PbI3/phenyl‐C61‐butyric acid methyl ester (PC61 BM)/buffer metal/Al are constructed. Through the choice of different buffer metals to tune work function of the cathode, the contact nature of the active layer with the cathode could be manipulated well. In comparison with the device using Au/Al as the electrode that shows an unfavorable band bending for conducting the excited electrons to the cathode, the one with Ca/Al presents a dramatically improved efficiency over 17.1%, ascribed to the favorable band bending at the interface of the cathode with the active layer. Details for tuning the band bending and the corresponding charge transfer mechanism are given in a systematic manner. Thus, a general guideline for constructing perovskite photovoltaic devices efficiently is provided. 相似文献
78.
79.
Zainal Abidin Ali Muhammad Aidil Roslan Rosiyah Yahya Wan Yusoff Wan Sulaiman Rustam Puteh 《IET nanobiotechnology / IET》2017,11(2):152
In this study, larvicidal activity of silver nanoparticles (AgNPs) synthesised using apple extract against fourth instar larvae of Aedes aegypti was determined. As a result, the AgNPs showed moderate larvicidal effects against Ae. aegypti larvae (LC50 = 15.76 ppm and LC90 = 27.7 ppm). In addition, comparison of larvicidal activity performance of AgNPs at high concentration prepared using two different methods showed that Ae. aegypti larvae was fully eliminated within the duration of 2.5 h. From X‐ray diffraction, the AgNP crystallites were found to exhibit face centred cubic structure. The average size of these AgNPs as estimated by particle size distribution was in the range of 50–120 nm. The absorption maxima of the synthesised Ag showed characteristic Ag surface plasmon resonance peak. This green synthesis provides an economic, eco‐friendly and clean synthesis route to Ag.Inspec keywords: silver, nanofabrication, X‐ray diffraction, zoology, particle size, nanoparticles, biomedical materials, nanomedicineOther keywords: time 2.5 h, size 50 nm to 120 nm, silver nanoparticle, larvicidal property, instar larvae, Aedes aegypti, larvicidal effect, larvicidal activity performance, X‐ray diffraction, nanoparticle particle size distribution, absorption maxima, silver surface plasmon resonance peak 相似文献
80.
Shuhua Zhang Muhammad Naeem Shah Feng Liu Zhongqiang Zhang Qin Hu Thomas P.Russell Minmin Shi Chang-Zhi Li Hongzheng Chen 《Nano Research》2017,(11):3765-3774
The ternary strategy for incorporating multiple photon-sensitive components into a single junction has emerged as an effective method for optimizing the nanoscale morphology and improving the device performance of organic solar cells (OSCs).In this study,efficient and stable ternary OSCs were achieved by introducing the small-molecule dye (5E,5'E)-5,5'-(4',4″-(1,2-diphenylethene-1,2-diyl)bis(biphenyl-4',4-diyl))bis(methan-1-yl-1-ylidene)bis(3-ethyl-2-thioxothia zolidin-4-one) (BTPERn) into poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiopheneco-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th):[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) blend films processed using a 1,8-diiodooctane (DIO)-free solvent.The incorporation of BTPE-Rn enhanced the short-circuit current density and fill factor of the ternary OSCs compared with those of binary OSCs.An investigation of the optical,electronic,and morphological properties of the ternary blends indicated that the third component of BTPE-Rn not only promoted the photon utilization of blends through the energy-transfer process but also improved the electron mobility of the blends owing to the fullerene-rich nanophase optimization.More importantly,this ternary strategy of utilizing a small-molecule dye to replace the photounstable DIO additive enhanced the operational stability of the OSCs. 相似文献