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from article Absorption
Incident sunlight is absorbed, reflected, and scattered by tree leaves. (Credit: Shutterstock / photolinc)
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from article Bioorganic chemistry
Vancomycin and an analog that is active against vancomycin-resistant bacteria.
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from article Bioorganic chemistry
Foldamers that mimic proteins.
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from article Bioorganic chemistry
The rate of this intramolecular lactonization, relative to that of intermolecular esterification, mimics the rate increase caused by an enzyme's binding and orienting substrates for a bimolecular reaction.
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from article Bioorganic chemistry
Intramolecular models of enzymatic general acid and general base catalysis. (a) Intramolecular general acid catalysis causes this acetal to hydrolyze at pH 7 more than 107 times faster than the corresponding acetal without the carboxylic acid group.…
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from article Bioorganic chemistry
An antibody raised against the phosphonate analog of a tetrahedral intermediate catalyzes the hydrolysis of cocaine to ecgonine methyl ester.
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from article Bioorganic chemistry
A functionalized cyclodextrin mimics the enzyme RNase by catalyzing the regioselective hydrolysis of a model phosphodiester.
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from article Bioorganic chemistry
Enzyme-catalyzed reactions that have been commercialized as industrial processes.
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from article Bioorganic chemistry
Mechanism of DNA scission by calicheamicin. Reductive or nucleophilic cleavage of the trisulfide triggers conjugate (Michael) addition to the enone, rehybridization of the bridgehead carbon, and Bergman cyclization of the enediyne, generating a…
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from article Flax
Flax plants (Linum usitatissimum) in bloom. (Photo by Howard F. Schwartz, Colorado State University)
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from article Flax
Flaxseeds. (Photo by Jose Hernandez, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)
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from article Flax
Yellow wilted leaves of flax plants infected by Fusarium oxysporum. (Photo by J. A. Hoes, Oilseed Diseases Image Collection, Western Committee on Plant Disease, Winnipeg, Manitoba, Canada)
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from article Flax
Blighted and moldy flaxseeds. (Photo by J. A. Hoes, Oilseed Diseases Image Collection, Western Committee on Plant Disease, Winnipeg, Manitoba, Canada)
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from article Peppermint
Peppermint (Mentha piperita). (Photo by Michael Thompson, Agricultural Research Service, U.S. Department of Agriculture)
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from article Liquid chromatography
Chromatogram showing the separation of various ethoxylates (nonionic surfactants) from an environmental water sample by liquid chromatography. EO = ethoxylate. Cx = alkyl. OP = octylphenol. NP = nonylphenol. (Credit: U.S. EPA)
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from article Citron
Citron (Citrus medica), including cross sections of the fruit. (Photo courtesy of California Citrus Clonal Protection Program)
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from article Cabbage
Cabbage (Brassica oleracea var. capitata). (Joseph Harris Co., Inc., Rochester, New York)
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from article Gelatin
Gelatin capsules. (Copyright © Digital Vision/SuperStock)
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from article Gelatin
Gelatin fruit dessert. (Credit: Getty Images/iStockphoto)
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from article Solid-state battery
Schematic illustration of an intercalation cathode reaction.
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from article Solid-state battery
Schematic diagram of solid-state battery.
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from article Acid and base
Ball-and-stick model of phosphoric acid (H3PO4). H = white. P = orange. O = red.
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from article Acid and base
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from article Hyperbolic navigation system
Typical grid of hyperbolic lines of position formed by a master (M) and two secondary stations (W and X).
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from article Hyperbolic navigation system
Individual lines of position from a master and two secondaries at location P. γ =LOP crossing angle.
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from article Hyperbolic navigation system
Typical curves of constant horizontal dilution of precision (HDOP) for a master (X) and two secondary stations (X and Y). Numbers give HDOP values of contours.
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from article Decomposition potential
Determination of decomposition potential.
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from article Vanadium
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from article Germanium
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from article Lespedeza
Sericea lespedeza (Lespedeza cuneata). (Photo by Chuck Bargeron, University of Georgia; Bugwood.org)
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from article Ice point
Arrangement for determining triple point.
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from article Ethylene
Structure of ethylene. (Black = carbon. White = hydrogen)
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from article Multicomponent reactions
Multistep syntheses. (a) “Classical” versus (b) “one-pot”.
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from article Multicomponent reactions
Three-component Strecker α-amino nitrile synthesis and its use in α-amino acid synthesis.
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from article Multicomponent reactions
Pseudo-four-component Hantzsch synthesis of dihydropyridines and nifedipine.
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from article Multicomponent reactions
Four-component Ugi synthesis of α-amino acyl amides.
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from article Multicomponent reactions
Classification of multicomponent reactions.
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from article Multicomponent reactions
Subclassification of organic reactivity into polar and nonpolar reactivity.
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from article Multicomponent reactions
Pd-catalyzed domino four-component synthesis of pyrroles.
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from article Multicomponent reactions
Consecutive Pd-Cu-catalysis-initiated four-component synthesis of tetrahydro-β-carbolines.
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from article Sisal
Sisal (Agave sisalana). (Photo courtesy of Peter Lapshin)
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from article Wool
Sheep at a research facility near Dubois, Idaho. (Photo courtesy of the Agricultural Research Service, U.S. Department of Agriculture)
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from article Wool
Longitudinal section of a completely developed nonmedullated wool follicle, including sebaceous and sweat glands.
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from article Wool
Cuticle, cortex, and medulla of a wool fiber.
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from article Wool
Scale formation of Delaine Merino wool fibers.
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from article Wool
Fine wool staples showing distinct crimp (wavy) patterns. The length shown is the minimum for each classification.
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from article Molybdenum
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from article Brazil nut
Unshelled Brazil nuts (Bertholletia excelsa). (Photo courtesy of C. E. Timothy Paine)
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from article Staining
Photomicrograph of Mycobacterium tuberculosis (the causative agent of tuberculosis) using the acid-fast Ziehl-Neelsen carbol fuchsin stain. In this case, the M. tuberculosis bacteria stain red (or reddish purple), whereas non-acid-fast species stain…
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from article Staining
Staining of Klebsiella bacteria using crystal violet. (Credit: Lisa Burgess/McGraw-Hill Education)
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from article Staining
Photomicrograph of a Gram-stained urethral exudate sample from a male who presented with a case of urethritis. Numerous extracellular Gram-negative Neisseria gonorrhoeae bacteria are evident. (Credit: Norman Jacobs/U.S. Centers for Disease Control…
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from article Castor plant
Seeds of the castor plant (Ricinus communis). These seeds, which are also known as castor beans, are processed to make castor oil. (Photo by Brian Prechtel, Agricultural Research Service, United States Department of Agriculture)
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from article Cowpea
Cowpea (Vigna unguiculata): pods and leaves. (Photo by Howard F. Schwartz, Colorado State University)
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from article Cowpea
Cowpea seeds, which are often called black-eyed peas. (Photo by Joseph Berger; Bugwood.org)
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from article Sulfur
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from article Kumquat
Fruits and foliage of the Nagami kumquat (Fortunella margarita). (Photo by Forest and Kim Starr)
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from article Mulberry
White mulberry (Morus alba). (Photo courtesy of Forest and Kim Starr)
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from article Beech
Leaf on top of bark of American beech (Fagus grandifolia). (Photo courtesy of Robert H. Mohlenbrock, USDA–NRCS PLANTS Database)
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from article Beech
Beechnuts of the American beech (Fagusgrandifolia). (Photo courtesy of Steve Hurst, USDA–NRCS PLANTS Database)
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from article Schuler pendulum
Basic principles illustrated by (a) simple pendulum; (b) Earth-radius pendulum; (c) solid pendulous rod.
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from article Schuler pendulum
Behavior of pendulous rod when accelerated about Earth. (a) Short-period pendulous rod. (b) Schuler-period pendulous rod. (c) Nonpendulous rod.
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from article Schuler pendulum
Gyropendulum; thrust bearing provides extra freedom, necessary for gyroscopic action.
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from article Schuler pendulum
Principle of Schuler-tuned stable platform.
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from article Catalysis and catalysts
The Hoveyda-Grubbs catalyst, molecular formula C31H38Cl2N2ORu, is a ruthenium-based metathesis catalyst.
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from article Superacid
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from article Superacid
Hammett acidity function (H0) values for some solutions in 100% H2SO4. (After E. F. Caldin and V. Gold, eds., Proton Transfer Reactions, Chapman and Hall, 1975)
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from article Superacid
Hammett acidity function (H0) values for acids of the fluorosulfuric acid solvent system. (After E. F. Caldin and V. Gold, eds., Proton Transfer Reactions, Chapman and Hall, 1975)
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from article Superacid
Hammett acidity function (H0) values for some HF−MF5 systems.
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from article Marjoram
Close-up view of marjoram (Majorana hortensis; alternatively Origanum majorana). (Photo courtesy of Forest and Kim Starr)
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from article Colloid
Examples of colloid particles. (a) Zinc sulfide (sphalerite). (b) Cadmium carbonate, with an enlargement of the boxed section (courtesy of Egon Matijević).
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from article Emulsion polymerization
Process of emulsion polymerization.
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from article Emulsion polymerization
Entry in emulsion polymerization.
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from article Emulsion polymerization
Spontaneous packing of low-polydispersity polystyrene particles about 200 nm in diameter.
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from article Emulsion polymerization
Monomers used in emulsion polymerization.
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from article Emulsion polymerization
Amphiphilic RAFT in emulsion polymerization.
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from article Qualitative chemical analysis
A qualitative analysis test-tube method for separating cations into ion groups. (Copyright © McGraw-Hill Education/Stephen Frisch)
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from article Chestnut
American chestnut (Castanea dentata). (Photo courtesy of Forest and Kim Starr)
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from article Chestnut
Nuts of the Allegheny chinquapin (Castanea pumila). (Photo courtesy of Steve Hurst, USDA–NRCS PLANTS Database)
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from article Caraway
Caraway (Carum carvi) fruits (often called “seeds”). Scale bar = 1 mm. (Photo by Steve Hurst; USDA–NRCS PLANTS Database)
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from article Air navigation
Typical wind triangle, drawn to scale. 1 knot = 1 nmi/h = 0.514 m/s.
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from article Air navigation
Electronic map display developed by a flight management computer on the pilot's instrument panel of a Boeing 767 airplane. (United Airlines)
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from article Air navigation
Loran C chain GRI 7980 in the southeastern United States, comprising master station M and slave stations W, X, Y, and Z. A position fix is shown at point A, where the lines of position 7980-Y-45000 and 7980-Z-61000 intersect.
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from article RNA World theory
Biochemical functions of the known natural ribozyme classes. Ribozymes are ribonucleic acid (RNA) molecules that can catalyze specific biochemical reactions. The self-cleaving ribozyme classes promote an internal phosphoester transfer reaction to…
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from article RNA World theory
Examples of possibly ancient riboswitches that bind RNA-derived compounds. Riboswitches for the essential cofactor thiamin (thiamine) pyrophosphate (TPP) are present in some species from all domains of modern life, whereas riboswitches for cyclic…
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from article Flame
Structure of a premixed laminar flame front.
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from article Flame
Structure of a laminar diffusion flame front.
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from article Dallis grass
Dallis grass (Paspalum dilatatum). (Photo courtesy of Larry Allain, USGS National Wetlands Research Center)
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from article Oriental vegetables
Bok choy, also known as pak choy or Chinese mustard (Brassica rapa or Brassica campestris, chinensis group). (Photo courtesy of the Agricultural Research Service, U.S. Department of Agriculture)
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from article Oriental vegetables
Oriental winter radish or daikon (Raphanus sativus, longipinnatus group). (Photo by Franco Folini)
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from article Oriental vegetables
Mung bean sprouts (Vigna radiata).
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from article Oriental vegetables
Chinese okra (Luffa acutangula). The length of the fruit can reach 30–38 cm (12–15 in.). (Photo by Forest and Kim Starr)
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from article Periodic table
Periodic table of the elements.
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from article Cotton effect
Behavior of the ORD and CD curves in the vicinity of an absorption band at wavelength λ0 (idealized). (a) Positive Cotton effect. (b) Negative Cotton effect.
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from article Cotton effect
Curves used to determine relative rotatory intensities. (a) Partial ORD curve. (b) Partial CD curve.
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from article Cotton effect
Structural formula of (+)-trans-9-methyl-1,4,9,10- tetrahydronaphthalene.
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from article Cotton effect
Schematic representation of the twisted diene chromophore showing the two possible handednesses; the numbering is as indicated in Fig. 3 (a) Right-handed. (b) Left-handed.
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from article Ebony
Persimmon (Diospyros virginiana). (Photograph by Dot Paul, National Resources Conservation Service, USDA)
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from article Tangerine
Tangerine fruits (Citrus reticulata). (Photo by Forest and Kim Starr)
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from article Forage crops
Bahia grass (Paspalum notatum), a popular warm-season grass used as a forage crop. (Photo by James H. Miller and Ted Bodner, Southern Weed Society)
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from article Forage crops
Alfalfa (Medicago sativa), the most important legume forage crop, cut and drying prior to its final harvest. (Photo by Howard F. Schwartz, Colorado State University)
