关于高清视频的一切

<正>现在,越来越多的数码单反相机可以拍摄高清视频了,在这里我们将向你深入浅出地讲解如何开始你的单反视频之旅。拍摄高清视频10问①数码单反相机拍摄的视频有统一的格式吗?没有。如果你觉得照片的JPEG、RAW和     

掌握测光模式

在你拍摄不同的物体时,使用不同的测光模式可能会得到完全不同的效果。下面就跟随我们的文章来探索测光模式的奥秘吧!     

控制画面的景深

有些照片的背景非常清晰,有些则完全虚化。为了表现不同的意境,我们会选择不同的景深。下面就让我们为你解答关于景深的问题吧。     

深度了解直方图

现在,在数码相机上都可以查看照片的直方图,但是直方图的意义是什么?怎么用它来检查照片的曝光呢?从下面这几页中你就能得到答案。     

Stabilisation of RNA bulges by oligonucleotide complements containing an adenosine analogue

Incorporation of 2'-deoxy-2'-beta-(1-naphthylmethyl)tubercidin into an oligodeoxyribonucleotide mostly has little or a slightly negative effect on the T(m) values of complexes with DNA complements. With the same naphthylmethyl-substituted nucleoside at the 3'-end of a 2'-O-methyloligoribonucleotide, however, a stabilisation of 1-2 degrees C in the corresponding complexes with both DNA and RNA is observed. When the target sequence is an RNA fragment forming a two- or three-nucleotide bulge, complexes with (naphthylmethyl)tubercidin-modified oligodeoxyribonucleotides, as well as with the corresponding 2'-O-methyloligoribonucleotides, give stabilisations of 1-2 degrees C for the three-nucleotide bulge and of almost 4 degrees C for the two-nucleotide bulge. This stabilisation is specific to RNA, since the corresponding complexes with the DNA fragments do not display this effect. Thus, the (naphthylmethyl)tubercidin-containing oligonucleotides are the first reported oligonucleotide modifications that specifically stabilise bulged RNA.     

Ben的DIY

<正>看看专业摄影师Ben Birchall用泡沫和吸管这些普通的材料能为照片注入怎样的活力吧!在拍摄肖像的时候,使用闪光灯非常普遍。但是如果你只把闪光灯放在相机上,那只能是为人的面部补些光线,无法发挥什么创意效果。所以我在拍摄人像的时候一     

单反专用闪光灯

如果你想为自己的数码单反相机买一支闪光灯,不要只考虑原厂闪光灯,还有很多高性价比的选择方案,我们的编辑为你选择了包括原厂闪光灯在内的6款闪光灯,下面就跟随文章来看看它们的表现吧。     

Detection of toxins involved in foodborne diseases caused by Gram‐positive bacteria

Bacterial toxins are food safety hazards causing about 10% of all reported foodborne outbreaks in Europe. Pertinent to Gram‐positive pathogens, the most relevant toxins are emetic toxin and diarrheal enterotoxins of Bacillus cereus, neurotoxins of Clostridium botulinum, enterotoxin of Clostridium perfringens, and a family of enterotoxins produced by Staphylococcus aureus and some other staphylococci. These toxins are the most important virulence factors of respective foodborne pathogens and a primary cause of the related foodborne diseases. They are proteins or peptides that differ from each other in their size, structure, toxicity, toxicological end points, solubility, and stability, types of food matrix to which they are mostly related to. These differences influence the characteristics of required detection methods. Therefore, detection of these toxins in food samples, or detection of toxin production capacity in the bacterial isolate, remains one of the cornerstones of microbial food analysis and an essential tool in understanding the relevant properties of these toxins. Advanced research has led into new insights of the incidence of toxins, mechanisms of their production, their physicochemical properties, and their toxicological mode of action and dose‐response profile. This review focuses on biological, immunological, mass spectrometry, and molecular assays as the most commonly used detection and quantification methods for toxins of B. cereus, C. botulinum, C. perfringens, and S. aureus. Gathered and analyzed information provides a comprehensive blueprint of the existing knowledge on the principles of these assays, their application in food safety, limits of detection and quantification, matrices in which they are applicable, and type of information they provide to the user.