全文获取类型
收费全文 | 121047篇 |
免费 | 12076篇 |
国内免费 | 6959篇 |
专业分类
电工技术 | 9083篇 |
技术理论 | 10篇 |
综合类 | 9778篇 |
化学工业 | 17944篇 |
金属工艺 | 7140篇 |
机械仪表 | 8522篇 |
建筑科学 | 10301篇 |
矿业工程 | 3900篇 |
能源动力 | 3650篇 |
轻工业 | 8829篇 |
水利工程 | 2736篇 |
石油天然气 | 6929篇 |
武器工业 | 1371篇 |
无线电 | 13812篇 |
一般工业技术 | 12425篇 |
冶金工业 | 5018篇 |
原子能技术 | 1427篇 |
自动化技术 | 17207篇 |
出版年
2024年 | 269篇 |
2023年 | 1861篇 |
2022年 | 3313篇 |
2021年 | 4743篇 |
2020年 | 3741篇 |
2019年 | 2986篇 |
2018年 | 3451篇 |
2017年 | 3794篇 |
2016年 | 3448篇 |
2015年 | 4926篇 |
2014年 | 6332篇 |
2013年 | 7266篇 |
2012年 | 8281篇 |
2011年 | 8850篇 |
2010年 | 8020篇 |
2009年 | 7833篇 |
2008年 | 8028篇 |
2007年 | 7317篇 |
2006年 | 7266篇 |
2005年 | 6021篇 |
2004年 | 4471篇 |
2003年 | 4233篇 |
2002年 | 4830篇 |
2001年 | 4132篇 |
2000年 | 2960篇 |
1999年 | 2561篇 |
1998年 | 1714篇 |
1997年 | 1438篇 |
1996年 | 1262篇 |
1995年 | 1124篇 |
1994年 | 928篇 |
1993年 | 657篇 |
1992年 | 501篇 |
1991年 | 384篇 |
1990年 | 297篇 |
1989年 | 225篇 |
1988年 | 171篇 |
1987年 | 119篇 |
1986年 | 88篇 |
1985年 | 36篇 |
1984年 | 34篇 |
1983年 | 29篇 |
1982年 | 35篇 |
1981年 | 31篇 |
1980年 | 22篇 |
1979年 | 17篇 |
1978年 | 3篇 |
1966年 | 1篇 |
1959年 | 17篇 |
1951年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Meimei Xia Jian Chen Xiao‐Jun Zeng 《International Transactions in Operational Research》2020,27(2):1080-1100
Existing approaches to data envelopment analysis focus mainly on the derivation of the efficiency of the individual decision‐making unit (DMU) or on the calculation of the weights of multiple inputs or outputs, but pay little attention to the team interest of all the DMUs. Motivated by the idea of team reasoning, in which the benefit of the team is of higher importance than that of each individual, this paper considers all the DMUs as a team and introduces the team indexes including the overall efficiencies, variance, boundaries of all the DMUs, and relationships between DMUs. Several models are first developed to estimate values of the team indexes based on which decision makers can provide their preferences regarding them. Then, models are established to obtain the interval efficiencies of individual DMUs under the condition that the team indexes are satisfied. Several examples are given to illustrate the proposed approaches and verify their applicability. 相似文献
83.
A method of garment factory workers’ performance monitoring using control chart based on RFID system
Gu Cong Zhou Ruifang Hu Luoyan Gao Guifen 《The International Journal of Advanced Manufacturing Technology》2020,107(3):1049-1059
The International Journal of Advanced Manufacturing Technology - Massive production data of front-line workers are recorded every day by RFID system in garment factory, which are mainly in multiple... 相似文献
84.
85.
移动床活性焦低温干法烟气多污染物脱除技术在钢铁烧结烟气脱硫脱硝工艺中具有良好的适用性,但烟气净化过程中活性焦的损耗成为制约该技术推广应用的关键因素之一。以宝钢烧结烟气脱硫脱硝工艺中所产生的废活性焦为研究对象,通过考察其比表面积、孔容结构、灰分中重金属及碱金属含量、表面官能团特征及脱硫脱硝性能,探究烟气净化过程中活性焦组成、结构及表面性质的变化。结果表明,与新鲜活性焦相比,废活性焦粒度集中分布在0.2?5 mm,其表面的氮、氧、硫元素及过渡金属氧化物含量显著增加,比表面积由191.0 m2/g增加至499.0 m2/g,使废活性焦颗粒在150℃下脱硝率由20%提升到70%,120℃下穿透硫容由0.27 mg SO2/g提升至11.08 mg SO2/g,显示了良好的再利用潜力。 相似文献
86.
婴戏纹饰即描绘儿童游戏时的画作,是中国人物画的一种,更是陶瓷装饰中常见的传统题材。其主要以儿童为主要绘画对象,表现儿童纯真,或借以其他物象,组成吉祥图案,在我国陶瓷绘画上广泛运用,有着深刻的社会形态特征和思想文化的背景。其始于唐代,兴盛于宋金,明清两朝日臻成熟,并延续至今。在西方艺术史当中,儿童形象大都通过神话人物或宗教相关的艺术品走进人们视野,用以表现某些宗教思想或精神诉求。本文主要探讨陶瓷婴戏纹饰在我国历史发展历程中的演变概况,以及笔者对我国陶瓷婴戏纹饰和西方艺术品中儿童形象横向对比下的一些思考。 相似文献
87.
Jianwei Fu Shaomin Wang Xuzhe Wang Ya Yan Kai Wang Meng Gao Qun Xu 《Journal of Porous Materials》2018,25(4):1081-1089
Heteroatom-containing porous carbon nanospheres with a high surface area were firstly fabricated by pyrolysis of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanospheres which were fabricated by a facile polycondensation between hexachlorocyclotriphosphazene and 4,4′-sulfonydiphenol. Then the porous carbon nanosphere-supported Pt nanoparticles (Pt NPs@C-PZS) were synthesized by a simple microwave reduction method, during which Pt NPs were highly dispersed on the surface of carbon supports. The surface morphologies and chemical composition of the as-obtained C-PZS and Pt NPs@C-PZS nanocomposites were characterized by SEM, TEM, XRD, XPS, and Raman spectroscopy. Characterization results showed that the Pt NPs with an average diameter of 2 nm was well anchored onto the surface of C-PZS nanospheres. In addition, the as-prepared Pt NPs@C-PZS nanocomposites exhibited an excellent catalytic capability towards the reduction of 4-nitrophenol to 4-aminophenol by excessive sodium borohydride (NaBH4) at room temperature. 相似文献
88.
A numerical study is performed to investigate the effects of jet hole shape and channel geometry on impingement cooling for both stationary and rotating condition. Two hole shapes and two channel geometries are introduced to counteract the adverse effects of centrifugal force and Coriolis force which are induced by rotation. Both the fluid and solid part are considered for realizing the conjugate heat transfer simulation. The unsteady k-ω SST turbulence model was employed to obtain the time-averaged Nusselt number distributions, time-averaged temperature and temperature gradient fields and the turbulent flow structure. The results show that the cooling jet from the racetrack-shaped hole can effectively withstand the intensive streamwise crossflow to enhance the heat transfer. The double swirling chamber (DSC) channel significantly improves the heat transfer characteristics on the cambered surface and diminishes the adverse effects of the Coriolis force. The high Nu number region is expanded while the temperature uniformity is improved. The combination of the racetrack-shaped hole and DSC channel provides the highest heat transfer among the four cases. The averaged Nu numbers on both the leading and trailing sides for all tested cases show obvious downtrend as rotation number increases, especially at high Reynolds number. 相似文献
89.
Xiao Wang Xiufeng Hao Dan Chang Chongyi Zhu Lili Chen Alideertu Dong Ge Gao 《应用聚合物科学杂志》2019,136(17):47419
N-halamine-based antibacterial agents have high efficiency and rechargeable antibacterial properties. However, their applications are limited due to their complex synthetic process and fuzzy antibacterial mechanism. In this study, a novel N-halamine antibacterial polymer was synthesized by inverse emulsion polymerization and characterized by Fourier transform infrared, nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Due to the difficulty of purification, most of the subjects studied previously were hydrophobic polymers, while little research on hydrophilic polymers. In this experiment, this difficulty was overcome by controlling the dosage of sodium hypochlorite and methods of dialysis. Because of the complex cell structure of Gram-negative bacteria, it is difficult for N-halamines to release the oxidizing chlorine into the cell. However, the hydrophilic N-halamines can solve this problem, which showed a stronger antibacterial effect on Gram-negative Escherichia coli synthesized in this study. In addition, the particle size and hydrophilic property of the polymer were changed by changing the amount of initiator, and the differences in their antibacterial properties were studied. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47419. 相似文献
90.
Forschung im Ingenieurwesen - The star-wheel reducer has been regarded as a promising alternative solution for industrial power transmission where large transmission ratio and high power... 相似文献