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   148篇
  免费   9篇
电工技术   2篇
化学工业   45篇
金属工艺   2篇
机械仪表   5篇
建筑科学   3篇
能源动力   13篇
轻工业   9篇
石油天然气   2篇
无线电   14篇
一般工业技术   47篇
冶金工业   4篇
自动化技术   11篇
  2024年   1篇
  2023年   9篇
  2022年   12篇
  2021年   4篇
  2020年   7篇
  2019年   11篇
  2018年   9篇
  2017年   4篇
  2016年   10篇
  2015年   8篇
  2014年   6篇
  2013年   12篇
  2012年   7篇
  2011年   7篇
  2010年   6篇
  2009年   5篇
  2008年   12篇
  2007年   8篇
  2006年   1篇
  2005年   2篇
  2002年   2篇
  2000年   1篇
  1996年   3篇
  1995年   3篇
  1994年   1篇
  1993年   2篇
  1989年   1篇
  1975年   1篇
  1974年   1篇
  1969年   1篇
排序方式: 共有157条查询结果,搜索用时 640 毫秒
51.
In this paper, a year around energy efficiency (EnE) and economic analysis of single slope solar still (SSSS), the single slope solar still with glass cooling (SSSSGC), the single slope solar still with basin heating (SSSSBH), and the single slope solar still with glass cooling and basin heating (SSSSGCBH) was carried out based on the distilled water production. The annual yield production from the SSSS, SSSSGC, SSSSBH, and SSSSGCBH were 476.16, 637.44, 970.24, and 1167.36 kg, respectively. The yearly yield produced from the SSSSBH and SSSSGCBH was increased by 50.92% and 59.21%, respectively, as compared with the SSSS. Moreover, the annual EnE of the SSSSGCBH was 28.75%. However, the EnE of the SSSS was 11.73%. Also, freshwater making cost is found to be 18.9, 24.9, 37.9, and 45.6 Rs/day for the SSSS, SSSSGC, SSSSBH, and SSSSGCBH, respectively, if the buying cost of freshwater is Rs 10.  相似文献   
52.
Uptake of methyl bromide was greater at high concentrations with an exposure period of 2 hr than at lower concentrations with an exposure period of 5 hr, but mortality did not increase accordingly. Some fumigant was desorbed from insects after treatment and desorption was greater in those exposed for the shorter period. Statistical analysis on the three major variables which contribute to toxicity, namely concentration, time and fumigant uptake, showed that, for purposes of calculation, only the two factors, concentration and time, need to be considered; inclusion of data on uptake into the model did not provide appreciable contribution to explain the observed mortalities beyond that already given by concentration and time. A model which includes concentration, time and interaction between the two was found to describe the dosage-response relationship better than concentration and time alone.  相似文献   
53.
54.
ZnS:Cu thin films have been deposited on glass substrate by a simple neutral pH solution synthesis route and chemical bath deposition technique. The copper concentration was varied between 0 and 0.1 M%. The X-ray diffraction and scanning electron microscope studies show the average size of the nanoparticles are below 4 nm (Bohr diameter). The effect of film thickness on the optical and structural properties has been studied. The optical absorption studies show the band gap energy of ZnS:Cu films decreases from 3.68 to 3.43 eV as thickness varied from 318.3 to 334.1 nm. The structural estimation shows the variation in particle size from 2.67 to 3.14 nm with thickness. The insignificant change in band gap may be due to the increase in particle size and quantum size effect.  相似文献   
55.
Non-destructive diagnosis of nano-scale pre-precipitation and precipitation events can provide valuable support in controlling the thermal treatment for achieving the peak aged or any alternate desired microstructural state. The aim of the present investigation is to study the effect of isothermal ageing on density and hardness of 2024 Al-Cu-Mg alloy, and also to search the ability of measured ultrasonic velocity and attenuation and calculated elastic constants for monitoring the variations in microstructure and precipitation events during ageing. The specimens aged at 463 K for various periods up to 32 h followed by a solution annealed at 766 K for 1 h and water quenched, have been used for the ultrasonic velocity and attenuation measurements and metallurgical studies. The initial sharp acceleration in the hardness and velocities is due to the depletion of Cu from solid solution associated with the formation and growth of Cu-Mg co-cluster (GPB zone) and other intermediate phases. The local maximum at 10 h ageing time is due to the presence of higher volume fraction of precipitates like S′ and S and the minimum at 32 h of ageing time is due to the existence of dissolution and coarsening of S′ and S precipitates by overaged effect.  相似文献   
56.
The benzylideneindolinone 6‐chloro‐3‐(3′‐trifluoromethylbenzylidene)‐1,3‐dihydroindol‐2‐one ( 4 ) was reported to exhibit potent and selective growth inhibitory effects on hepatocellular carcinoma (HCC). Corroborative evidence supported multi‐receptor tyrosine kinase (RTK) inhibition as a possible mode of action. However, the poor physicochemical properties of 4 limited its furtherance as a lead compound. In this study, the modification of 4 was investigated with the aim of improving its potency and physicochemical profile. The 6‐fluorobenzylideneindolinone 3‐12 bearing a 3′‐N‐propylaminosulfonyl substituent was found to be a promising substitute. Compound 3‐12 [6‐fluoro‐3‐(3′‐N‐propylaminosulfonylbenzylidene)‐1,3‐dihydroindol‐2‐one] was found to be tenfold more soluble than 4 and to have sub‐micromolar growth inhibitory activities on HCC cells. It is apoptogenic and inhibits the phosphorylation of several RTKs in HuH7, of which the inhibition of FGFR4 and HER3 are prominent. Compound 3‐12 decreased the tumor load in a physiologically relevant orthotopic HCC xenograft murine model. Structure–activity relationships support pivotal roles for the fluoro and N′‐propylaminosulfonyl moieties in enhancing cell‐based activity and moderating the physicochemical profile (solubility, permeability) of 3‐12 .  相似文献   
57.
The present investigation is aimed to evaluate fatigue crack growth parameters of gas tungsten arc, electron beam and laser beam welded Ti–6Al–4V titanium alloy for assessing the remaining service lives of existing structure by fracture mechanics approach. Center cracked tensile specimens were tested using a 100 kN servo hydraulic controlled fatigue testing machine under constant amplitude uniaxial tensile load. Crack growth curves were plotted and crack growth parameters (exponent and intercept) were evaluated. Fatigue crack growth behavior of welds was correlated with mechanical properties and microstructural characteristics of welds. Of the three joints, the joint fabricated by laser beam welding exhibited higher fatigue crack growth resistance due to the presence of fine lamellar microstructure in the weld metal.  相似文献   
58.
An adaptive three-dimensional isogeometric formulation based on rational splines over hierarchical T-meshes (RHT-splines) for problems in elasto-statics and elasto-dynamics is presented. RHT-splines avoid some short-comings of NURBS-based formulations; in particular they allow for adaptive h-refinement with ease. In order to drive the adaptive refinement, we present a recovery-based error estimator for RHT-splines. The method is applied to several problems in elasto-statics and elasto-dynamics including three-dimensional modeling of thin structures. The results are compared to analytical solutions and results of NURBS based isogeometric formulations.  相似文献   
59.
The chlorosulphonylisocyanate reacts smoothly with C60 in xylene under thermal conditions in a [2+2]-cycloaddition fashion to yield the bisadduct as one of the products in the inseparable reaction mixture. The reaction product is analysed by FAB-MS, 13C NMR, FT-IR and HPLC techniques. Results show the formation of imino-lactone as one of the favourable products.  相似文献   
60.
Peters RD  Lay OP  Jeganathan M 《Applied optics》2008,47(21):3920-3926
Nulling interferometry has been proposed for the direct detection of Earth-like planets. Deep stable nulls require careful control of the relative intensity and phase of the beams that are being combined. We present a novel compensator, the Adaptive Nuller, that corrects the intensity and phase as a function of wavelength from 8 to 12 microm using a deformable mirror. This compensator has been used to produce rejection ratios of 82,000:1 over a bandwidth of 3.2 microm centered around 10 microm.  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