首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9514篇
  免费   698篇
  国内免费   458篇
电工技术   1167篇
综合类   576篇
化学工业   2755篇
金属工艺   1344篇
机械仪表   348篇
建筑科学   102篇
矿业工程   134篇
能源动力   1043篇
轻工业   292篇
水利工程   29篇
石油天然气   103篇
武器工业   45篇
无线电   668篇
一般工业技术   1052篇
冶金工业   474篇
原子能技术   95篇
自动化技术   443篇
  2024年   10篇
  2023年   133篇
  2022年   183篇
  2021年   245篇
  2020年   278篇
  2019年   263篇
  2018年   191篇
  2017年   312篇
  2016年   256篇
  2015年   257篇
  2014年   439篇
  2013年   477篇
  2012年   514篇
  2011年   830篇
  2010年   597篇
  2009年   640篇
  2008年   581篇
  2007年   707篇
  2006年   612篇
  2005年   463篇
  2004年   428篇
  2003年   352篇
  2002年   329篇
  2001年   285篇
  2000年   232篇
  1999年   183篇
  1998年   182篇
  1997年   127篇
  1996年   100篇
  1995年   97篇
  1994年   103篇
  1993年   62篇
  1992年   46篇
  1991年   36篇
  1990年   30篇
  1989年   19篇
  1988年   17篇
  1987年   9篇
  1986年   8篇
  1985年   15篇
  1984年   10篇
  1983年   7篇
  1981年   3篇
  1980年   1篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The dye industry produces a large amount of hazardous wastewater every day worldwide, which brings potential threaten to the global environment. As an excellent method for removal of water chroma and chemical oxygen demand, electrocatalytic methods are currently widely used in the treatment of dye wastewater. The selection and preparation of electrode materials and electrocatalysts play an important role on the electrocatalytic treatment. The aim of this paper is to introduce the most excellent high-efficiency electrode materials and electrocatalysts in the field of dye wastewater treatment. Many electrode materials such as metal electrode materials, boron-doped diamond anode materials and three-dimensional electrode are introduced in detail. Besides, the mechanism of electrocatalytic oxidation is summarized. The composite treatment of active electrode and electrocatalyst are extensively examined. Finally, the progress of photo-assisted electrocatalytic methods of dye wastewater and the catalysts are described.  相似文献   
2.
《Ceramics International》2021,47(21):29908-29918
The cellulose derived carbon/graphene/ZnO aerogel composite was prepared as an electrode in order to investigate the electrochemical properties. Carbon aerogel was synthesized using paper as an available cellulose source, and the composite was obtained through a new and simple preparation method including the immersion of monolithic carbon aerogel in graphene oxide/Zn2+ suspension and subsequent chemical reduction and freeze drying. The morphology, functional groups and crystalline structure of the samples were studied with Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction Spectroscopy (XRD), respectively. Electrochemical performance of the prepared binder free electrodes was examined using Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS). The data revealed that flexible carbon/graphene/ZnO composite resulted in a low density (0.035 g cm−3) electrode with the capacitance of 900 mF cm−2 at a high current density of 10 mA cm−2, lower IR drop and high cyclic stability (capacitance retention of 96%) after 1000 cycles, at 10 mA cm−2. These features were due to the presence of 3D porous conductive network, highly reduced graphene oxide, and the formation of ZnO nanoparticles on graphene sheets. Moreover, polyaniline (PANI) was introduced to carbon/graphene/ZnO composite electrode using electro-oxidation method at different reaction time and aniline concentration in order to achieve remarkably improved capacitance of 2500 mF cm−2 (at 10 mA cm−2) and low charge transfer resistance. Also, after the supercapacitor device assembly, the capacitance was retained. Based on the results, the synthesized composite is a promising material for new generation of lightweight freestanding electrodes with the high electrochemical performance.  相似文献   
3.
The structural and electrochemical properties of the double perovskite-type oxide, PrBaMnMoO6-δ, was investigated using neutron diffraction with in-situ conductivity measurement under a dry Argon atmosphere from 25 °C to 700 °C. A Rietveld refinement of the neutron diffraction data confirmed monoclinic symmetry in the P21/n space group. Rietveld refinement also confirms the unit cell parameters of a = 5.6567 (1) Å, b = 5.6065 (2) Å, c = 7.9344 (1) Å and β = 84.43° with reliable atomic positions and refinement factors (R-factors). Neutron diffraction data refinement shows two minor phases (<5%), an orthorhombic AB2O5 type phase of PrMn2O5 in the Pbam (No. 32) space group with unit cell parameters, a = 7.9672 (1) Å, b = 8.9043 (2) Å and c = 5.8540 (1) Å and a scheelite phase of BaMoO4 in the tetragonal I41/a (88) space group with the unit cell parameters, a = b = 5.9522 (1) Å, and c = 12.3211 (2) Å. Morphological images revealed a porous and intertwined microstructure. In-situ conductivity measurement shows that the total conductivity of this material was 130.84 Scm?1 at 700 °C.  相似文献   
4.
电化学传感器检测植物生长调节剂的研究进展   总被引:1,自引:0,他引:1  
近年来,植物生长调节剂(PGRs)的检测方法备受研究者广泛关注。由于电化学传感器具有较高的灵敏度和选择性、响应时间短、成本低、方便携带等优点,在现场快速检测中受到研究者的青睐。从电化学传感器检测PGRs的4个方面进行了总结:1)直接电化学行为传感,主要是通过不同的修饰材料对电极进行增敏,从而实现对具有电化学活性的PGRs进行直接检测;2)电化学生物传感,主要通过酶和抗原抗体对PGRs进行特异性识别;3)光电化学传感,主要是利用具有光催化性能的材料实现对电化学活性较差的PGRs进行光电转化检测;4)分子印迹电化学传感,通过构建能够特异性识别PGRs的聚合物薄膜从而进行专属检测。同时对电化学传感器现状进行了阐述以及对未来发展趋势进行展望。  相似文献   
5.
Wire arc additive manufacturing(WAAM)has been investigated to deposit large-scale metal parts due to its high deposition efficiency and low material cost.However,in the process of automatically manufacturing the high-quality metal parts by WAAM,several problems about the heat build-up,the deposit-path optimization,and the stability of the process parameters need to be well addressed.To overcome these issues,a new WAAM method based on the double electrode micro plasma arc welding(DE-MPAW)was designed.The circuit principles of different metal-transfer models in the DE-MPAW deposition process were analyzed theoretically.The effects between the parameters,wire feed rate and torch stand-off distance,in the process of WAAM were investigated experimentally.In addition,a real-time DE-MPAW control system was developed to optimize and stabilize the deposition process by self-adaptively changing the wire feed rate and torch stand-off distance.Finally,a series of tests were performed to evaluate the con-trol system's performance.The results show that the capability against interferences in the process of WAAM has been enhanced by this self-adaptive adjustment system.Further,the deposition paths about the metal part's layer heights in WAAM are simplified.Finally,the appearance of the WAAM-deposited metal layers is also improved with the use of the control system.  相似文献   
6.
《Ceramics International》2021,47(24):34845-34850
The interfacial delamination of electrode/ceramic multilayer structure will seriously damage the reliability of low temperature co-fired ceramic (LTCC) module in practical applications. In this work, three kinds of glasses employed in Au electrode are designed and prepared to study the abnormal expansion and delamination process in the Au/ceramic LTCC multilayer structure. The interfacial delamination in the co-fired structure is found to be attributed to the abnormal expansion of glass in respect to Au electrode at high temperature, which is originated from the enlarged closed pores during the co-firing process. This conclusion is further confirmed by co-firing the sample in a low-pressure condition. The mechanism and elimination of interfacial delamination here provides a feasible solution for the design of novel glasses in Au electrode for LTCC applications.  相似文献   
7.
Gas diffusion layer (GDL) is one of the most important components of fuel cells. In order to improve the fuel cell performance, GDL has developed from single layer to dual layers, and then to multiple layers. However, dual or multi layers in GDL are usually prepared by layer-by-layer methods, which cost too much time, energy, and resources. In this work, we successfully developed a facile one-step method to prepare a GDL with three functional layers by utilizing the different sedimentation rates and filtration rates of short carbon fiber (CF) and carbon nanotube (CNT). The treatment temperature for this GDL is much lower than that of traditional method. The thickness of the GDL can be effectively controlled from as thin as 50 μm to more than 200 μm by simply adjusting the content of CF. The GDL with high flexibility is suitable to develop high performance flexible electronics. The fuel cell with the GDL has the maximum power density 1021 mW cm?2, which shows 19% improvement comparing to the conventional one. Therefore, this work breaks the traditional concept that GDL for fuel cells only can be prepared by very complex and high-cost procedure.  相似文献   
8.
黏结剂对电极的性能有着重要的影响。本文设计并制备了一种新型水性聚(乙烯-乙烯醇)-磺酸锂(EVOH-SO3Li,简称ES-Li)电极黏结剂,并对其键接结构及组成进行分析;对其溶解性、电解液稳定性、热稳定性进行测试;对所制电极柔性、微观形貌及电化学性能进行研究。经与聚(乙烯-乙烯醇)(EVOH)及商业的聚偏氟乙烯(PVDF)黏结剂进行对比。结果表明:ES-Li水性黏结剂具有不溶解于电解液,热稳定性良好等优点;ES-Li黏结剂制备负极柔性及微观形貌优良,采用ES-Li作为负极黏结剂的电池在电化学稳定窗口、界面阻抗、首次循环效率、循环及倍率等方面均表现优异,ES-Li负极的首次库仑效率为89.93%,在1C下循环100次的容量保持率为96.93%,且在2C、5C倍率下的循环性能均优于EVOH及PVDF制备的负极,具有应用潜力及商业化前景。  相似文献   
9.
This paper carefully evaluates the electrocatalytic activity of Sr2FeMo0.5Mn0.5O6 (SFMM) double perovskite as a candidate to substitute the state-of-the-art Ni/YSZ fuel electrode. The electrochemical performance of a 40% SFMM/CGO composite electrode was studied in CO/CO2 and H2 with different oxygen partial pressure. Two different cell configurations are prepared at a relatively low temperature of 800 °C to increase the electrochemically active surface area. The cell was supported with a 150 μm 10Sc1CeSZ electrolyte in the first configuration. The cell in the second configuration was made by applying a 400 nm thin 8YSZ layer on 150 μm CGO electrolyte to improve the electrolyte ionic conductivity. Improving catalytic activity with increasing oxygen partial pressure is a key characteristic of the developed electrode. The polarization resistance of about 0.34 and 0.56 Ω cm2 at 750 °C in 3%H2O + H2 and 60% CO/CO2 makes this electrode a promising candidate for SOCs application.  相似文献   
10.
对多壁碳纳米管 (MWCNT) 进行回流酸处理,增加其表面活性获得羧基化多壁碳纳米管(CMWCNT),结合聚乙烯醇 (PVA) 形成多功能导电水凝胶。借助CMWCNT表面羧基活性基团,与多重络合、纠缠的PVA链形成广泛氢键,构建CMWCNT-PVA水凝胶分层网络。通过丝网印刷工艺,制备CMWCNT-PVA自愈合柔性电极,该电极具有高电导率(35.1 S/m) 、高机械强度 (2000次循环弯曲) 和约10秒的自愈合特性,愈合后电路中,在大变形下也保持优异导电性和稳定性,且由柔性电路设计制备的发光二极管阵列,能够呈现HF发光图案。该自愈合柔性电极为柔性电路发展提供一种新的策略,对拓展电子皮肤、软体机器人和可穿戴设备等在人机交互中的应用具有重要科学意义。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号