The chemistry of life

Xem 1-20 trên 53 kết quả The chemistry of life
  • p 01-01-1970   Download

  • Th ere is something about being human that instills in us a sense of wonder. When we stop to think about it, the very idea of life seems such a mystery. Where did we come from? How did life begin? When we look at the sky, we wonder about the vastness of the universe and whether other life may exist there. If we look through a microscope at a drop of pond water, we are amazed at the variety of tiny creatures we see. Since cells form the very basis of life, it is only natural that our sense of wonder extends to the cell. Where did...

    pdf0p hotmoingay 03-01-2013 33 7   Download

  • A new 3 -acetoxy-urs-23,28,30-trioic acid, named acantrifoic acid B (1), has been isolated from the leaves of Acanthopanax trifoliatus. Its chemical structure has been characterized on the basis of spectral and chemical evidence. I - INTRODUCTION Acanthopanax trifoliatus (L.) Merr., (Araliaceae) is distributed in North Vietnam and used in the folk medicines of south–east Asia (Chi, 1997; Loi, 2001) as a drug with ginsenglike activity. Lupane-triterpene carboxylic acids and a lupane-triterpene glycoside have been reported from the leaves of A. trifoliatus (Ty et al.

    pdf4p muananghe 05-08-2013 21 2   Download

  • Faculty of Chemistry, College of Natural Science, Vietnam National University Anticancer Agent Research Laboratory, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea Summary Two flavone C-glucosides vitexin (1) and isovitexin (2) were isolated as the major constituents with the total content of 59.5% of the methanol extract of the Croton tonkinensis leaves along with an minor acylated flavonol O-glucoside kaempferol 3-O- D-(6’’-O-coumaroyl)glucopyranoside (tiliroside, 3) (0.9%)....

    pdf4p muananghe 05-08-2013 24 5   Download

  • This paper presents some thermomechanical characteristics of crosslinked poly(vinyl chloride) (PVC) samples such as glass transition temperature (Tg), softening point (Ts), and linear thermal expansion coefficient ( ). Probe load of 0.05 N is most suitable to evaluate expansion, softening and contraction of the crosslinked PVC samples. Tg , Ts and of the crosslinked PVC samples are higher than those of the uncrosslinked samples.

    pdf5p muananghe 05-08-2013 23 1   Download

  • Dracaena angustifolia Roxb. (Dracaenaceae) is locally known as Nam ginseng (ginseng from the South) in Quang Nam province. Its underground parts are used as tonic and for treatment of leukemia.1 In our continuing studies on Vietnamese medicinal plants, we have examined the constituents of Nam ginseng (D. angustifolia) and isolated three new spirostanol sapogenins. This paper reports the isolation and structure elucidation of these new compounds.

    pdf5p muananghe 05-08-2013 17 1   Download

  • The first edition of Toxicological Chemistry (1989) was written to bridge the gap between toxicology and chemistry. It defined toxicological chemistry as the science that deals with the chemical nature and reactions of toxic substances, their origins and uses, and the chemical aspects of their exposure, transformation, and elimination by biological systems. It emphasized the chemical formulas, structures, and reactions of toxic substances. The second edition of Toxicological Chemistry (1992) was significantly enlarged and increased in scope compared to the first edition.

    pdf424p crazy_sms 10-05-2012 110 57   Download

  • Lichen is a special form of life is formed by the symbiosis between algae and some fungi. The mycelium absorbs water and minerals provide the algae. Algae due to chlorophyll, use them to make organic matter to feed on both sides. In this common life of algae and fungi have a certain role, neither party relying solely on the real nao.Hinh is called symbiosis.

    pdf147p nhatro75 12-07-2012 71 20   Download

  • Science seeks to understand and explain our world, be that its physical composition (geology), chemical composition (chemistry), the way its composite matter interacts (physics), or the organisms that inhabit it (biology). We can only get an idea of what life is all about by piecing together information from each discipline to give us the big picture. We don’t have to look very far to realize that it is difficult, if not impossible, to separate biology from chemistry. After all, our body is a bag of chemicals.

    pdf0p qsczaxewd 25-09-2012 43 7   Download

  • Resilience is natural. Even after a long, hard winter, when the proper conditions arrive, nature simply springs back to life of its own accord. Resilience may be natural, yet every day we encounter people who are enduring a hard inner winter, whose joy and vitality have long ago gone dormant. Many of them have lost heart. Having tried all the usual remedies with little success, they wonder if they will ever fully reclaim their lives. They come to us with a single question, framed in a thousand different ways: “What can I do to feel better, to bring myself back to life, to recover the joy...

    pdf224p taurus23 27-09-2012 28 3   Download

  • The isomeranzin, a coumarin was isolated from the leaves of Clausena heptaphylla. The structure was elucidated by IR, MS, 1H and 13C-NMR. For the first time, the anti-Herpes simplex virus type 1 & 2 in vitro activity of the compound was reported and discussed. I - introduction Clausena heptaphylla (Roxb.) W. & Arn. (Rutaceae) (Vietnamese name: Giæi 7 l¸) is a tropical tree [1]. This species is also widely used in traditional medicine. In Asia (China, India, Vietnam, etc.), it is used for fever.

    pdf6p muananghe 05-08-2013 16 1   Download

  • I got the opportunity to associate myself with Dr. Raj Pal Singh, senior scientist, Polymer Chemistry Division, National Chemical Laboratory Pune, as my supervisor. As an outstanding scientist and teacher he has given me the benefit of his guidance throughout the course work. I am grateful to him for showing me all the angles of research life.

    pdf199p dangmya1989 05-05-2011 153 15   Download

  • Over the last two centuries, human activity has transformed the chemistry of Earth’s water and air, altered the face of Earth itself, and rewoven the web of life. Why has this ...

    doc8p bacenvirgeo 27-11-2010 176 14   Download

  • The pharmacy profession and the role of pharmacists in the modern healthcare systems have evolved quite rapidly over the last couple of decades. The services that pharmacists provide are expanding with the introduction of supplementary prescribing, provision of health checks, patient counselling and many others. The main ethos of pharmacy profession is now as much about keeping people healthy as treating them when they are not well.

    pdf398p nhutretho 30-01-2013 30 12   Download

  • This book is intended to be a presentation of alkaloids from chemical, biological and ecological points of view. It is a text for chemists, biologists and ecologists alike. However, the intended audience of this work is not limited to scientists, teachers and other present and future specialists. In fact, I wrote this book because I felt the need for it as a university educator and as a scientific enthusiast on the subject.

    pdf315p phoebe75 01-02-2013 44 13   Download

  • I was delighted to respond to an invitation from Ventus Publishing to write a book on atmospheric pollution. It is a topic well enough served by books in the past, but has become increasingly important during these early years of the 21st Century. I believe therefore that there is a place for a review like this one and that notwithstanding the immense activity in the area the book will have a reasonable shelf life. This is because it continually relates the discussion to the principles of physics and chemistry, and these do not change....

    pdf109p tuanloc_do 04-12-2012 30 1   Download

  • After studying this chapter, you should be able to accomplish the following outcomes: Distinguish between matter, elements, and atoms; name the six elements that are basic to life; describe the structure of an atom; tell why an atom can have isotopes; give examples of how low levels and high levels of radiation can each be helpful;...

    ppt41p tangtuy07 02-04-2016 5 1   Download

  • Biochemistry is the study of the chemical composition and reactions of living matter. All chemicals in the body fall into one of two major classes: organic or inorganic compounds. Organic compounds contain carbon. All organic compounds are covalently bonded molecules, and many are large. All other chemicals in the body are considered inorganic compounds. These include water, salts, and many acids and bases. Organic and inorganic compounds are equally essential for life.

    ppt51p tangtuy07 02-04-2016 10 1   Download

  • Chemistry is the scientific study of matter, method and variable nature of the substance applied in life. About chemical elements, compounds, atoms, molecules, and the chemical reactions occurring among the component.Chemistry developed from alchemy, has been practiced for thousands of years ago in China, Europe and India

    pdf57p truongbao 25-07-2009 692 310   Download

  • Phytochemistry is a broad area, generally termed ‘‘plant chemistry.’’ Investigations in the field of phytochemistry are important for numerous research disciplines, such as plant physiology, plant biochemistry, chemosystematics (which is often referred to as chemotaxonomy), plant biotechnology, and pharmacognosy. Plant physiology focuses on the life processes occurring in plants. Especially important are the investigations on the influence of various external factors, such as ultraviolet–visible (UV–Vis) radiation, temperature, the nature of soil, the climate, etc.

    pdf888p thanhthao567 20-12-2011 90 34   Download


Đồng bộ tài khoản