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   42篇
  免费   3篇
电工技术   2篇
化学工业   5篇
机械仪表   2篇
建筑科学   3篇
轻工业   2篇
水利工程   1篇
无线电   7篇
一般工业技术   6篇
冶金工业   6篇
自动化技术   11篇
  2024年   1篇
  2023年   2篇
  2021年   1篇
  2019年   2篇
  2018年   3篇
  2014年   1篇
  2013年   5篇
  2012年   3篇
  2011年   4篇
  2010年   2篇
  2009年   1篇
  2006年   7篇
  2003年   1篇
  2002年   1篇
  2001年   5篇
  2000年   1篇
  1996年   1篇
  1994年   1篇
  1992年   1篇
  1988年   1篇
  1978年   1篇
排序方式: 共有45条查询结果,搜索用时 15 毫秒
1.
2.
High ozone levels are regularly measured during summer months over the inland and mountainous regions of Israel. Studies analyzing the back trajectories of air masses responsible for the high ozone levels showed that the precursors originated from the densely populated Israeli coastline. In order to better understand the contribution of those emission sources to ozone production, it is essential to have an accurate emission inventory that can be inputted into a photochemical model. The present paper describes the methods used in preparing an emission inventory for Israel based on information available and published until 1998. The source and accuracy of the data available are described. The calculations performed and the assumptions taken in order to obtain data not directly available are clarified. The sources reported in the inventory were the major polluters (power plants, oil refineries, and cement industries); industry; transportation; and biogenic sources. The pollutants studied were SO2, NOx, CO, saturated and unsaturated hydrocarbons, ethylene, isoprene, toluene, xylene, formaldehyde, and aldehydes. The inventory showed that transportation is responsible for almost the entire CO and 30% of the volatile organic compounds emitted, although transportation itself accounts for only a fifth of total fuel consumption. About 75% of the NOx emitted can be attributed to industrial sources and the remaining 25% to transportation. Model simulations using the emission inventory were performed and compared to data available from a monitoring station situated 30 km east of Tel Aviv. The results showed good agreement, validating the accuracy of the emission inventory. The present emission inventory provides an important database as input to photochemical models used in forecasting ozone levels over Israel.  相似文献   
3.
太赫兹脉冲能量测量   总被引:1,自引:0,他引:1  
利用太赫兹波的单啁啾脉冲电光探测技术,通过调节实验装置中λ/4波片晶轴与探测激光线偏振方向成45°,可以巧妙地得到太赫兹波的绝对电场强度.利用CCD阵列,通过抽运探测的方法可以得到太赫兹脉冲的光斑尺寸,进而在两步实验的基础上计算得到太赫兹脉冲的能量.提供了一种行之有效的测量太赫兹脉冲能量的实验方案.  相似文献   
4.
The possibility of functional roles played by platelets in close alliance with cancer cells has inspired the design of new biomimetic systems that exploit platelet–cancer cell interactions. Here, the role of platelets in cancer diagnostics is leveraged to design a microfluidic platform capable of detecting cancer‐derived extracellular vesicles (EVs) from ultrasmall volumes (1 µL) of human plasma samples. Further, the captured EVs are counted by direct optical coding of plasmonic nanoprobes modified with EV‐specific antibodies. Owing to the inherent properties of platelets for multifaceted interaction with cancer cells, the microfluidic chip equipped with a biologically interfaced platelet membrane‐cloaked surface (denoted “PLT‐Chip”) can capture a significantly higher number of EVs from multiple types of cancer cell lines (prostate, lung, bladder, and breast) than the normal cell‐derived EVs. Furthermore, this chip allows the monitoring of the growth of tumor spheroids (100 µm–2.5 mm) and clearly distinguishes the plasma of cancer patients from that of normal healthy controls. This robust, multifaceted, and cancer‐specific binding affinity, coupled with excellent biocompatibility, is a unique feature of platelet membrane‐cloaked surfaces, which therefore represent promising alternatives to antibodies for application in EVs‐based cancer theranostics.  相似文献   
5.
The article investigates the structural and optical properties of ZnPc/PbSe hybrid multilayer (HML) structure deposited by using thermal evaporation technique. The X-ray diffraction pattern reveals the formation of ZnPc–PbSe composite and strain induced quantum size effect. Scanning electron microscope image shows the spherical grains for as-deposited film and nanorod like structure for the annealed film. The rods are oriented along one direction and stacking axis changes with the function of annealing temperature. The optical spectra show strong absorption in UV–Visible region and the optical absorption edge was red shifted for annealed samples. The luminescence properties were enhanced with broad emission in the range of 375–400 nm in HMLs. The optical band gap values are calculated and it varies from 3.2 to 3.04 eV with the function of annealing temperature and the band gap splitting was observed for a higher temperature of annealed samples. Strain-induced effect on ZnPc/PbSe HML has been reported using Raman spectra.  相似文献   
6.
We present an all solid-state, high voltage pulsed power supply for inducing stable plasma formation (density ~10(18) cm(-3)) in gas-filled capillary discharge waveguides. The pulser (pulse duration of 1 μs) is based on transistor switching and wound transmission line transformer technology. For a capillary of length 40 mm and diameter 265 μm and gas backing pressure of 100 mbar, a fast voltage pulse risetime of 95 ns initiates breakdown at 13 kV along the capillary. A peak current of ~280 A indicates near complete ionization, and the r.m.s. temporal jitter in the current pulse is only 4 ns. Temporally stable plasma formation is crucial for deploying capillary waveguides as plasma channels in laser-plasma interaction experiments, such as the laser wakefield accelerator.  相似文献   
7.
Reports an error in "The attentional blink reflects retrieval competition among multiple rapid serial visual presentation items: Tests of an interference model" by Matthew I. Isaak, Kimron L. Shapiro and Jesse Martin (Journal of Experimental Psychology: Human Perception and Performance, 1999[Dec], Vol 25[6], 1774-1792). On p. 1778, the correct Figure 1 was inadvertently replaced in the production process with an erroneous figure. The erratum contains the corrected figure. (The following abstract of the original article appeared in record 2000-15288-019.) When people respond to a target (T1) in a rapid serial visual presentation stream, their perception of a subsequent target (T2) is impaired if the intertarget stimulus onset asynchrony is between about 100 and 500 ms. Three experiments supported the interference model's (K. L. Shapiro, J. E. Raymond, & K. M. Arnell, 1994) claim that this attentional blink reflects competition for retrieval among multiple items in visual short-term memory. Experiments 1 and 2 revealed that items appearing during the blink are named as T2 on an above-chance proportion of trials when T2 must be identified. Experiment 3 demonstrated that both the size of the blink and sensitivity to T2 reflected the number of items competing for retrieval as T2; such competition, moreover, occurred at a conceptual or categorical level rather than at a purely visual one. The relationship between the interference and alternative models of the attentional blink is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
Presents an interpretation of American Psycho (1990). The film is described as a screen illustration of malignant narcissism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Exosomes—nanosized extracellular vesicles (EVs) naturally secreted from cells—have emerged as promising biomarkers and potential therapeutic vehicles, but methods to manipulate them for engineering purposes remain elusive. Among the technical obstacles are the small size and surface complexity of exosomes and the complex processing steps required, which reduce the biocompatibility of currently available methods. The encapsulation of exosomes with a nanofilm of supramolecular complexes of ferric ions (Fe3+) and tannic acid is demonstrated here. The resulting natural polyphenol, ≈10 nm thick, protects exosomes from external aggressors such as UV‐C irradiation or heat and is controllably degraded on demand. Furthermore, gold nanoparticles can be covalently attached for single‐exosome level visualization. To fully exploit their therapeutic potential, chemotherapeutic drug‐loaded EVs are functionalized to achieve the targeted, selective killing of cancer cells preferentially over normal cells. This nanofilm not only preserves the native size and chemical makeup of the intrinsic exosomes, but also confers new capabilities for efficient tumor targeting and pH‐controlled release of drugs. Demonstrating a scalable method to produce biocompatible, durable, on‐demand degradable, and chemically controllable shields for exosome modification and functionalization, the methods introduced here are expected to bring the potential of exosome‐based nanomedicine applications closer to reality.  相似文献   
10.
Here, the foot force distribution for a six‐legged walking machine is resolved for minimum energy consumption over a full cycle for regular wave gaits. Some insects utilize horizontal foot forces to reduce muscle forces and energy consumption [R. J. Full, R. Blickhan, and L. H. Ting, J. Exp. Biology 158 (1991), 369–390]. Foot force distribution for minimum energy consumption when applied to the walking machine, also supports this observation. In this study, geometric work loss for a walking machine with articulated legs is minimized by controlling interaction forces at the foot‐ground interface. Minimum energy foot forces are studied for various duty factors, lateral offsets, link proportions, and friction between foot and ground. © 2001 John Wiley & Sons, Inc.  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