耕地资源约束下中国农产品进口策略分析——基于虚拟耕地视角的研究

基于虚拟耕地的视角,本文提出了一种以解决耕地资源短缺为目标的农产品进口策略,并运用中国农业政策分析模型对策略效果进行情景模拟分析。研究表明:实施全面开放的油料大豆进口策略,比基准期节约出176万公顷豆田,其中123万公顷转化为粮田,使谷物自给率提高1.35%;实施全面开放的油料大豆进口和有限开放的棉花进口策略,比基准期节约出243万公顷棉花、大豆的种植田,其中142万公顷转化为粮田,使谷物自给率提高1.85%;实施全面开放的油料大豆进口和有限开放的棉花与玉米进口策略,能够优先保证口粮的绝对安全,使稻谷、小麦的自给率分别提高2%和2.2%。最后,提出了相应的政策建议。     

刑事照相常用紫外光源照射对DNA检验的影响研究

目的探究刑事照相常用紫外光源照射不同客体上的血指印和汗潜指印后对DNA检验产生的影响。方法分别使用254nm和365nm紫外光源在不同照射距离,不同照射时间下对不同客体表面制备的原血指印、微量血指印和汗潜指印检材进行照射,随后进行DNA定量分析。结果原血指印经紫外照射后对DNA检验结果无显著影响,微量血指印和汗潜指印经紫外照射对后续DNA检验结果认定影响较大。结论紫外光波长越短、功率越大、照射距离越短、照射时间越长,对DNA检验结果的影响越大。     

红外热成像技术及其在安防领域中的应用

红外基础理论1800年,英国物理学家F.W.赫胥尔从热的观点来研究各种色光时,发现了红外线。红外线是一种电磁波,具有与无线电波及可见光一样的本质,红外线的发现是人类对自然认识的一次飞跃,为研究、利用和发展红外技术领域开辟了一条全新的广阔道路。     

大豆合同与FOSFA仲裁

作为进口方的中国与出口方的美国、巴西及阿根廷之间的大豆贸易,2003年中国进口额达2100万公吨。这使中国成为世界最大的大豆进口国,大豆输入到中国用于加工,制成食用豆油,同时豆饼则作为动物饲料。然而,大豆的贸易为极少数国际谷物交易商所垄断:Cargill,Bunge,Dreyfus,ADM和其他的交易商。合约一般依据卖方的标准合同条款,指定如有争议则按照FOSFA1规则在伦敦进行仲裁解决。本文讨论两个问题:(1)标准合同是否将合约风险公平分配;(2)伦敦FOSFA仲裁是否适当或理想。背景现时讨论以上的两个问题最为合时,原因:2004年5月24日,中华人民共…     

热像捕"痕"

在现代化条件下,犯罪分子的作案手法越来越高明,他们总是绞尽脑汁力图避免留下蛛丝马迹,但是,他们却不能使自己发热的身体隐藏起来,不可避免地犯罪分子会在作案现场留下红外线热像,这无形、无色、无味的热像在现代红外线成像技术的帮助下,将令犯罪分子原形毕露——□文/陈光岳在现代侦破题材的警匪故事片中,我们不难看到这样的镜头:夜深人静时,公安部门突然接到报案,可是,当公安人员赶到现场时,犯罪分子却早已逃之夭夭,去无影踪了。赶到现场的公安人员当然不会就此罢休,他们把灯关掉,拿出照相机,对着尚有余热的被窝和犯罪分子出现过的地方连…     

红外照相拍照烧过纸上的汗液指印

犯罪现场有时留有被烧过的纸张,其上留有案犯的指印。这类指印的拍照提取能使案件有可能侦破。在普通光下,一般很难发现这类指印的存在。笔者经多次拍照试验,发现红外线照相方法可使烧焦后变黑的纸张还原其白色,而纸张上留有的被烧后的汗液指印纹线呈黑色调。 1 原理在红外光的照射下,被焚烧后的纸张强烈反射红外光,用红外胶片纪录后呈现为黑色调;而有指印纹线的部位,由于在焚烧过程中,汗液与     

浅谈蛋清的长期保存

2%鸡蛋清生理盐水(简称蛋清)在热解离试验中常作为检材粘附剂使用.蛋清随配随用最好,但这样做费时费力,极不方便.本文介绍一种蛋清的长期保存方法,目的是一次配制后长期使用.方法:用紫外线灯照射实验室,使实验室或实验室局部形成无菌环境.在无菌环境中取新鲜鸡蛋一只,按容积比配制2%蛋清生理盐水.用磁力搅拌器搅拌,滤纸过滤,按0.5m1～1ml的容积分装在小安瓶内,酒精     

红外技术再现消褪的热敏纸传真文件内容

1原理热敏纸的制作原理是在普通纸基上涂敷微粒粉末,成分是无色染料苯酚类或其他酸性物质,以薄膜相隔,在受热条件下,薄膜融化,粉末混合起显色反应。热敏纸上显色的字迹不稳定、易消褪,导致文件内容肉眼无法辨认。将消褪的热敏纸传真文件置于蓝绿光下,经激发后发射红外线,通过记录传真文件发射红外线的亮度分布,从而使消褪的热敏纸传真文件的内容获得再现。2方法2.1设备及软件(1)多波段光源;(2)Cooled-scope红外照相观察(1)将消褪的热敏纸传真文件平放于Cooled-scope红外照相观察系统的镜头下方,与镜头垂直;(2)打开多波段光源,用蓝绿光照射…     

烹饪原料中大豆卵磷脂的研究分析——响应面法优化超声波提取大豆卵磷脂工艺研究及HPLC-ELSD检测大豆卵磷脂含量

本文主要研究了超声波辅助法萃取大豆粉中的卵磷脂的工艺条件及HPLC-ELSD检测样品中卵磷腊的含量,确定最佳工艺条件.利用响应面分析法对超声波提取大豆卵磷脂的工艺进行优化.在单因素试验基础上,选择超声温度、超声时间、液料比和溶剂浓度为自变量,以大豆卵磷脂提取率为响应值,采用中心组合设计的方法,研究各自变量及其交互作用对卵磷脂提取率的影响.利用Design Expert 8.0.5.0分析确定最佳提取工艺,得出超声波提取大豆卵磷脂工艺的最佳条件为超声水浴温度50℃、液料比35∶1、超声功率100W、超声时间50min.在此条件下,卵磷脂提取率为5.4mg/g.     

意识流小说的困境

欧美的意识流小说在20-40年代曾显赫一时,并对后来的文学创作、文艺理论的发展产生了极其深远而广泛的影响。但好景不长,它很快就衰落了,意识流小说陷入了困境,这是必须正视的事实。从表面上看.意识流小说面临的最大问题是:缺乏可读性,没有一个人敢于宣称完全看懂了意识流小说;多数读者难以卒读,这的确是让意识流小说家头痛不已的问题,尽管乔伊斯曾硬着头皮宣称:“假如《尤利西斯》不适合阅读,那么生活便不适合生存”;但     

Establishing of chemical composition of printing ink

The subject of the examinations was primarily court tax marks of 50 and 200 PLN, which were suspected not to be genuine. Both inks on the questioned marks as well as comparative genuine marks and inks sent by the manufacturer were analyzed. No information about their chemical composition was available from manufacturer. In the examinations, infrared (IR), visible, X-ray fluorescence, and Raman spectrometry were used. The examinations showed that inks and glue on the marks of both values were the same as samples of those sent by the manufacturer. Discrepancies in some results were observed probably due to contamination, that is, an accidental presence of the foreign substance on the surface (e.g., sweat, saliva while sticking the marks to the surface or physical handling of the documents). It was concluded that there are original (genuine) court tax marks.     

Determination of the sequence of intersecting lines from laser toner and seal ink by Fourier transform infrared microspectroscopy and scanning electron microscope / energy dispersive X-ray mapping

The aim of this study was to verify that the combination of Fourier transform infrared microspectroscopy and scanning electron microscope / energy dispersive X-ray mapping could be applied to line intersection problems. The spectral data of red seal ink, laser toner and their intersections, such as peak location and peak intensity, were described. Relative peak height ratios of different chemical components in intersecting lines were used to distinguish the sequences. Energy dispersive X-ray mapping characteristics of intersecting areas were also detailed. The results show that both the laser toner and the seal ink appear on the surface of intersections, regardless of the sequence. The distribution of the two inks on the surface is influenced not only by the sequence of heterogeneous lines but also by diffusion. Fourier transform infrared microspectroscopy and scanning electron microscope/energy dispersive X-ray mapping are able to explore the chemical components and the corresponding elemental distribution in the intersections. The combination of these two techniques has provided a reliable method for sequencing intersecting lines of red seal ink and laser toner, and more importantly, this method may be a basis for sequencing superimposed lines from other writing instruments.     

Morphological and spectroscopic measurements of plastic bags for the purpose of discrimination

The discrimination of noncolored transparent polyethylene bags was studied by several nondestructive and semidestructive analytical methods. X-ray diffraction, infrared spectroscopy, and optical microscopy (differential interference contrast microscopy and phase contrast microscopy) were applied to polyethylene films. X-ray diffraction was used to distinguish variations in the crystalline phase, infrared spectroscopy was used to distinguish variations in the molecular components, and optical microscopy was used to distinguish the different surface morphologies. The results show that X-ray diffraction classifies the crystalline phase of the film depending on whether it is made from low-density polyethylene, linear low-density polyethylene, or high-density polyethylene; that infrared spectroscopy is useful to distinguish the molecular components and it is the most discriminating technique; and that optical microscopy discriminate films easily by their morphological differences.     

The detection and enhancement of latent fingermarks using infrared chemical imaging

The use of a new technique, Fourier transform infrared (FTIR) chemical imaging, has been demonstrated for the enhancement of latent fingermarks on a number of surfaces. Images of untreated fingermarks on glass backgrounds with excellent ridge detail were acquired using infrared chemical imaging. High quality fingermarks on glass backgrounds were also developed using ethyl cyanoacrylate (super glue) fuming and subsequent infrared chemical imaging. This new method allows the collection of images from backgrounds that traditionally pose problems for current fingermark detection methods. The background may, for example, be highly colored, have a complex pattern, or possess other pattern or image characteristics that make it difficult to separate fingermark ridges using traditional optical or luminescent visualization. One background that has proven to be a challenging surface for the development of latent fingermarks is the Australian polymer banknote. To demonstrate the power and applicability of infrared chemical imaging, fingermarks fumed with ethyl cyanoacrylate were successfully imaged from Australian polymer banknotes.     

Investigation into the merits of infrared imaging in the investigation of tattoos postmortem

Infrared imaging has a history of use in the forensic examination of artwork and documents and is investigated here for its wider use in the detection of tattoos on the human body postmortem. Infrared photographic and reflectographic techniques were tested on 18 living individuals, displaying a total of 30 tattoos. It was observed that neither age, sex, age of the tattoo, nor, most significantly, skin color affected the ability to image the tattoos using infrared imaging techniques. Second, a piglet carcass was tattooed and the impact of the decomposition process on the visibility of the tattoos assessed. Changes were recorded for 17 days and decomposition included partial mummification and skin discoloration. Crucially, the discoloration was recorded as greatly affecting the image quality using conventional photography, but was insignificant to the infrared recording of these tattoos. It was concluded that infrared reflectography was beneficial in the investigation into tattoos postmortem.     

Infrared Imaging of the Crime Scene: Possibilities and Pitfalls

All objects radiate infrared energy invisible to the human eye, which can be imaged by infrared cameras, visualizing differences in temperature and/or emissivity of objects. Infrared imaging is an emerging technique for forensic investigators. The rapid, nondestructive, and noncontact features of infrared imaging indicate its suitability for many forensic applications, ranging from the estimation of time of death to the detection of blood stains on dark backgrounds. This paper provides an overview of the principles and instrumentation involved in infrared imaging. Difficulties concerning the image interpretation due to different radiation sources and different emissivity values within a scene are addressed. Finally, reported forensic applications are reviewed and supported by practical illustrations. When introduced in forensic casework, infrared imaging can help investigators to detect, to visualize, and to identify useful evidence nondestructively.     

基于单波长红外图像检验纸载体表面目标物 K粉的研究

目的 建立快速评估4种纸张载体表面是否存在K粉的无损检验方法.方法 采集纸载体表面可能附着K粉区域的红外图像,以K粉红外特征吸收峰获得对应的单波长红外图像,据图像分析区域内表征的各组分红外光谱和空间分布信息评估K粉的存在.结论 该检验方法所需样品量少,为无损检验,可快速评估纸载体表面是否存在K粉,为气质联用等检验方法提供定性检验目标.     

The effect of ionizing gamma radiation on natural and synthetic fibers and its implications for the forensic examination of fiber evidence

Circumstances of criminal activities involving radioactive materials may mean fiber evidence recovered from a crime scene could have been exposed to materials emitting ionizing radiation. The consequences of radiation exposed fibers on the result of the forensic analysis and interpretation is explored. The effect of exposure to 1-1000 kGy radiation doses in natural and synthetic fibers was noticeable using comparative forensic examination methods, such as optical microscopy, microspectrophotometry, and thin-layer chromatography. Fourier transform infrared spectroscopy analysis showed no signs of radiation-induced chemical changes in any of the fiber structures. The outcome of the comparative methods highlights the risk of "false negatives" associated in comparing colors of recovered fibers that may have been exposed to unknown radiation doses. Consideration of such results supports the requirement to know the context, including the environmental conditions, as much as possible before undertaking a forensic fiber examination.     

The application of infrared chemical imaging to the detection and enhancement of latent fingerprints: method optimization and further findings

Fourier transform infrared (FTIR) chemical imaging allows the collection of fingerprint images from backgrounds that have traditionally posed problems for conventional fingerprint detection methods. In this work, the suitability of this technique for the imaging of fingerprints on a wider range of difficult surfaces (including polymer banknotes, various types of paper, and aluminum drink cans) has been tested. For each new surface, a systematic methodology was employed to optimize settings such as spectral resolution, number of scans, and pixel aggregation in order to reduce collection time and file-size without compromising spatial resolution and the quality of the final fingerprint image. The imaging of cyanoacrylate-fumed fingerprints on polymer banknotes has been improved, with shorter collection times for larger image areas. One-month-old fingerprints on polymer banknotes have been successfully fumed and imaged. It was also found that FTIR chemical imaging gives high quality images of cyanoacrylate-fumed fingerprints on aluminum drink cans, regardless of the printed background. Although visible and UV light sources do not yield fingerprint images of the same quality on difficult, nonporous backgrounds, in many cases they can be used to locate a fingerprint prior to higher quality imaging by the FTIR technique. Attempts to acquire FTIR images of fingerprints on paper-based porous surfaces that had been treated with established reagents such as ninhydrin were all unsuccessful due to the swamping effect of the cellulose constituents of the paper.     

Forensic analysis of bicomponent fibers using infrared chemical imaging

The application of infrared chemical imaging to the analysis of bicomponent fibers was evaluated. Eleven nominally bicomponent fibers were examined either side-on or in cross-section. In six of the 11 samples, infrared chemical imaging was able to spatially resolve two spectroscopically distinct regions when the fibers were examined side-on. As well as yielding characteristic infrared spectra of each component, the technique also provided images that clearly illustrated the side-by-side configuration of these components in the fiber. In one case it was possible to prepare and image a cross-section of the fiber, but in general the preparation of fiber cross-sections proved very difficult. In five of the 11 samples, the infrared spectra could be used to identify the overall chemical composition of the fibers, according to a published classification scheme, but the fiber components could not be spatially resolved. Difficulties that are inherent to conventional "single-point" infrared spectroscopy, such as interference fringing and sloping baselines, particularly when analyzing acrylic type fibers, were also encountered in the infrared chemical image analysis of bicomponent fibers. A number of infrared sampling techniques were investigated to overcome these problems, and recommendations for the best sampling technique are given. Chemical imaging results were compared with those obtained using conventional fiber microscopy techniques.