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   332篇
  免费   12篇
  国内免费   12篇
电工技术   14篇
化学工业   52篇
金属工艺   4篇
机械仪表   5篇
建筑科学   14篇
矿业工程   7篇
能源动力   24篇
轻工业   16篇
水利工程   4篇
石油天然气   6篇
无线电   51篇
一般工业技术   51篇
冶金工业   82篇
自动化技术   26篇
  2023年   6篇
  2022年   5篇
  2021年   10篇
  2020年   7篇
  2019年   2篇
  2018年   7篇
  2017年   7篇
  2016年   7篇
  2015年   8篇
  2014年   11篇
  2013年   18篇
  2012年   16篇
  2011年   22篇
  2010年   10篇
  2009年   11篇
  2008年   10篇
  2007年   8篇
  2006年   13篇
  2005年   12篇
  2004年   7篇
  2003年   8篇
  2002年   6篇
  2001年   6篇
  2000年   2篇
  1999年   7篇
  1998年   22篇
  1997年   15篇
  1996年   8篇
  1995年   12篇
  1994年   5篇
  1993年   3篇
  1991年   3篇
  1990年   7篇
  1989年   2篇
  1988年   4篇
  1986年   2篇
  1985年   6篇
  1984年   3篇
  1983年   3篇
  1982年   5篇
  1980年   4篇
  1979年   2篇
  1978年   5篇
  1976年   2篇
  1974年   2篇
  1972年   3篇
  1961年   1篇
  1960年   1篇
  1949年   1篇
  1943年   1篇
排序方式: 共有356条查询结果,搜索用时 281 毫秒
51.
This paper presents initial information on the development and validation of three team task analysis scales. These scales were designed to quantitatively assess the extent to which a group of tasks or a job is team based. During a 2-week period, 52 male students working in 4-person teams were trained to perform a complex highly interdependent computer-simulated combat mission consisting of both individual- and team-based tasks. Our results indicated that the scales demonstrated high levels of interrater agreement. In addition, the scales differentiated between tasks that were predetermined to be individual versus team based. Finally, the results indicated that job-level ratings of team workflow were more strongly related to team performance than were aggregated task-level ratings of team-relatedness or team workflow. These results suggest that the scales presented here are an effective means of quantifying the extent to which tasks or jobs are team based. A research and practical implication of our findings is that the team task analysis scales could serve as criterion measures in the evaluation of team training interventions or predictors of team performance.  相似文献   
52.
Journal of Materials Science: Materials in Electronics - Nonlinear optical organometallic single crystal of manganese mercury thiocyanate (MMTC) has been grown by SR method in aqueous solution. The...  相似文献   
53.
This work aims at augmenting the amount of potable water using MgO and TiO2 in stepped solar still. Experiments were carried out for the climatic conditions of Chennai, India, with two different concentrations of nanofluids inside a stepped basin under three different cases. Results show that there is an improvement in yield of fresh water from stepped solar still by 33.18% and 41.05% using 0.1% and 0.2% volume concentration of TiO2 nanofluid, respectively, whereas the freshwater yield from stepped still with MgO nanofluids improved by 51.7% and 61.89%. Furthermore, the economic analysis revealed that the cost of potable water from the modified solar still reduced from 0.029 to 0.016 $/kg. Similarly, the useful annual energy, yearly cost per kilogram, and annual cost per kilowatt hour are significantly profitable with the use of MgO nanofluid in the stepped basin and found as 512.46 kWh, 0.025 $/kg, and 0.026 $/kWh, respectively. It is also found that the cost of potable water from the modified still significantly increases as the amount of fresh water produced is decreased with increased fabrication cost of the solar still.  相似文献   
54.
Although 2D layered metal compounds are widely exploited using various techniques such as exfoliation and vapor-phase-assisted growth, it is still challenging to construct the 2D materials in a 3D configuration with preservation of the unique physicochemical properties of the metal compounds. Herein, a general synthetic strategy is reported for a wide variety of 2D (atomic-scale thickness) metal compounds with 3D bicontinous nanoporous structure. 19 binary compounds including sulfides, selenides, tellurides, carbides, and nitrides, and five alloyed compounds, are successfully prepared via a surface alloy strategy, which are readily created by using a recyclable nanoporous gold assisted chemical vapor deposition process. These 3D nanoporous metal compounds with preserved 2D physicochemical properties, tunable pore sizes, and compositions for electrocatalytic applications, show excellent catalytic performance in the electrochemical N2 reduction reaction. This work opens up a promising avenue for fundamental studies and potential applications of a wide variety of nanoporous metal compounds.  相似文献   
55.
Flexible and lightweight supercapacitors with superior mechanical flexibility and outstanding capacity are regarded as an ideal power source for wearable electronic devices. Meanwhile, incorporating additional novel characters such as transparency and electrochromism can further benefit the development of smart supercapacitors. Nevertheless, the application of the commonly used planar-structural current collectors is seriously restricted by their intrinsic properties such as poor rigidity, large thickness, and limited loading surface area. Flexible and ultralight current collectors with 3D architecture, high conductivity, and easy integration are believed to be the most appropriate alternatives to build high-performance supercapacitors. In this study, a novel and scalable manufacturing technique is developed to produce a flexible and ultralight 3D Ni micromesh (3D NM) current collector for supercapacitor. Flexible smart supercapacitor integrated by 3D NM and high active Ni–Co bimetallic hydroxide (3D NM@NiCo BH) delivers a considerable rate performance (60.6% capacity retention from 1 to 50 mA cm−2). Furthermore, the fabricated hybrid supercapacitor device integrated with electrochromic functionality can visually indicate the energy level by a color display. This flexible electrochromic supercapacitor based on ultralight 3D Ni micromesh provides a novel insight into multifunctional energy storage systems for smart wearable electronic devices.  相似文献   
56.
Ultraflexible and ultralight rechargeable aqueous Zn-ion batteries (ZIBs) with the merits of environmental benignity and high security arise as promising candidates for flexible electronic systems. Nowadays, the energy density and cyclical stability of ZIBs on metal-based rigid substrates reach a satisfactory level, while the inflexible substrates severely prevent them from widespread commercial adoption in portable electronics. Although flexible substrates-engineered devices burgeon, the development of flexible ZIBs with high specific energy still faces great challenges. Herein, a flexible ultrathin and ultralight Zn micromesh (thickness of 8 µm and areal density of 4.9 mg cm−2) with regularly aligned microholes is fabricated via combining photolithography with electrochemical machining. The unique microholes-engineered Zn micromesh presents excellent flexibility, enhanced mechanical strength, and better wettability. Moreover, numerical simulations in COMSOL and in situ microscopic observation system certify the induced spatial-selection deposition of Zn micromesh. Accordingly, aqueous ZIBs constructed with polyaniline-intercalated vanadium oxide cathode and Zn micromesh anode demonstrate exceptional high-rate capability (67.6% retention with 100 times current density expansion) and cyclical stability (maintaining 87.6% after 1000 cycles at 10.0 A g−1). Furthermore, the assembled pouch cell displays superb flexibility and durability under different scenarios, indicating great prospects in high-energy ZIBs and flexible electronics.  相似文献   
57.
This paper examines the synthesis of a toughened elastomer fromVernonia galamensis seed oil by reacting vernonia oil with vernonia oil-derived suberic acid (octanedioic acid), and cross-linking the pre-polymer in the immediate presence of cross-linked polystyrene preparedin situ. The paper also demonstrates that the progress of reaction can be followed by monitoring the generation of hydroxyl groups using infrared spectroscopy. Analysis of some crystalline material on the cooler parts of the reaction vessels revealed the presence of component fatty acids of vernonia oil. Transmission electron microscopy characterization of the synthesized toughened elastomer suggests that vernonia oil-suberic acid polyester and polystyrene polymer are interpenetrating.  相似文献   
58.
Particle formation process during spray drying profoundly impacts particle morphology and microstructure. This study experimentally investigated the formation of core‐shell‐structured microparticles by one‐step drying of composite droplets made of Eudragit® RS (a polycationic acrylic polymer in nanoparticle form) and silica sol. The formation of an incipient surface shell was monitored using single droplet drying technique, and the freshly formed shell was recovered for subsequent analyses. Adding silica to RS precursor increased the shell formation time and altered the properties of the incipient shell from water‐dispersible to nondispersible. The incipient shell formed from RS/silica droplets with mass ratios of 1.5%:1.5% and 0.5%:2.5% showed ingredient segregation with a preferential accumulation of RS, similar to the shell region of dried microparticles. After shell formation, excess silica sol in the liquid phase could flow inward, producing a dense core. This mobility‐governed solute migration would be useful for constructing core‐shell microparticles using other precursor systems. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3297–3310, 2017  相似文献   
59.
In this paper, the structure‐property relationships of a clay ceramic with organic additives (biomass and biochar) are investigated to develop an alternative material for thermal energy storage. The firing transformations were elucidated using X‐ray pair distribution function analysis, differential scanning calorimetry, and scanning electron microscopy. It was found that the biomass increased the porosity, which resulted in a decrease of the specific heat capacity. On the other hand, the biochar remained in the clay ceramic without any interaction with the clay matrix up to 950°C. The specific heat capacity of the clay ceramic increased from 1.20 to 1.49 kJ/kg·K for a 30 wt% addition of biochar. The clay ceramic with a 30 wt% addition of biochar also conserved a high flexural strength of 11.1 MPa compared to that of the clay ceramic without organic additives (i.e., 18.9 MPa). Furthermore, the flexural strength only decreased by 23% after 100 thermal cycles. The crack growth associated with the thermal fatigue was limited by crack bridging and crack trapping. Hence, the current results suggest that clay/biochar ceramics can be as efficient as molten salts in thermal energy storage with the added benefit of an ease of use in the physical form of bricks.  相似文献   
60.
In this paper, an experimental study of the conventional solar still (CSS), the conventional solar still with glass cooling (CSSGC), the conventional solar still with basin heating (CSSBH), and the conventional solar still with glass cooling and basin heating (CSSGCBH) was carried out on the basis of the distilled water production, the energy efficiency (EnE), the exergy efficiency (ExE), and economic analysis. The CSSGC and CSSBH contain Peltier modules for cooling the glass and heating the basin. The evaporative heat transfer coefficient for all the experimental stills was calculated. The values of daily distilled water production from the CSSGCBH, CSSBH, CSSGC, and CSS were 4.56, 3.79, 2.49, and 1.89 kg/m2, respectively. The daily distilled yield of the CSSBH and CSSGCBH were increased by 58.55% and 50.13%, respectively, as compared with the CSS. Moreover, the daily EnE and ExE of the CSSGCBH were 27.03% and 3.5%, respectively, whereas the EnE and ExE of the CSS were 10.88% and 1.3%, respectively. Furthermore, the cost of distilled water production was found to be 0.26, 0.35, 0.53, and 0.64 $/day for the CSS, CSSGC, CSSBH, and CSSGCBH, respectively, if the selling price of the distilled water was Rs10.  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