Search Results

10 | 25 | 50 | 100 items per page

4,120 results

Project

Heart-Rate Monitor

This project uses a sensitive light-detecting resistor to detect small changes in the light beaming through your finger as your blood pumps through tiny arteries in the finger. This device is not the same as the heart-rate monitors typically used in…

Image

from article Microtechnique

Image

from article Microtechnique

Materials and method for applying cover slip to balsam wholemount. (a) Correct way; notice that the cover slip is held vertically centered over the drop of balsam. (b) Wrong way; this method draws the object to one side. (After P. Gray, Handbook of…

Image

from article Microtechnique

Making a smear preparation. (a) Place the drop about 1 in. (2.5 cm) from end of slide. (b) Apply a second slide just in front of the drop. (c) Push slide smoothly forward to spread the smear. (After P. Gray, Handbook of Basic Microtechnique, 3d ed.,…

Image

from article Microtechnique

Rotary microtome produced by the American Optical Co. (From P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)

Image

from article Microtechnique

Method of mounting the wax block on the block holder. (After P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)

Image

from article Microtechnique

Basic steps in cutting and mounting paraffin ribbons prior to staining. (a) Starting the ribbon. (b) Cutting the ribbon in lengths. (c) Mounting the dry ribbon. (d) Flooding the ribbons. (e) Warming the flooded ribbons to flatten them. (After P.…

Image

from article Microtechnique

Coplin jars for starting a slide through the reagent series. (After P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)

Image

from article Bioorganic chemistry

Vancomycin and an analog that is active against vancomycin-resistant bacteria.

Image

from article Bioorganic chemistry

Foldamers that mimic proteins.

Image

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.

Image

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.…

Image

from article Bioorganic chemistry

An antibody raised against the phosphonate analog of a tetrahedral intermediate catalyzes the hydrolysis of cocaine to ecgonine methyl ester.

Image

from article Bioorganic chemistry

A functionalized cyclodextrin mimics the enzyme RNase by catalyzing the regioselective hydrolysis of a model phosphodiester.

Image

from article Bioorganic chemistry

Enzyme-catalyzed reactions that have been commercialized as industrial processes.

Image

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…

Image

from article Type 1 diabetes

One characteristic feature of type 1 diabetes is glomerulosclerosis (Kimmelstiel-Wilson lesion), which involves the scarring or hardening of the glomeruli (blood vessels) in the kidneys. (Copyright © McGraw-Hill Education)

Image

from article Type 1 diabetes

Stages in the development of type 1 diabetes. (Credit: Type 1 Diabetes TrialNet)

Image

from article Parathyroid gland

Image

from article Parathyroid gland

Common positions of human parathyroid glands on the posterior aspect of the thyroid. (After W. H. Hollinshead, Anatomy of the endocrine glands, Surg. Clin. N. Amer., 32(4):1115–1140, 1952)

Image

from article Parathyroid gland

Section of human parathyroid gland, demonstrating the two main parenchymal cell types. Zenker-formal fixation, Mallory-azan stain. (After D. Bloom and D. W. Fawcett, A Textbook of Histology, 9th ed., Saunders, 1968)

Image

from article Parathyroid gland

Image

from article Yeast

Colorized scanning electron micrograph (SEM) of Schizosaccharomyces pombe yeast. This single-celled fungus is studied widely as a model organism for eukaryotic cell division. It is a rod-shaped yeast that grows by elongation at its ends, and it…

Image

from article Yeast

Cell shapes of yeasts are extremely varied: (a) rectangular; (b) pear-shaped; (c) apiculate; (d) ogival; (e) spherical; (f) globose; (g) ellipsoidal (oval); (h) elongate; (i) tetrahedral.

Image

from article Yeast

Colorized scanning electron micrograph (SEM) of cells of brewer's yeast (Saccharomyces cerevisiae). This yeast consists of single vegetative cells. Small daughter cells can be seen budding off from the larger cells. Saccharomyces cerevisiae ferments…

Image

from article Yeast

Yeast mycelia. (a) A true septate mycelium showing a break to form an arthrospore. (b) A pseudomycelium.

Image

from article Yeast

Heterothallic (bifactorial) life cycle of a basidiomycetous yeast, Leucosporidium scottii.

Image

from article Yeast

A fluorescent antibody stain reveals the oval budding yeast cells of Candida albicans. This yeast is the most common human fungal pathogen. (Credit: Maxine Jalbert and Leo Kaufman/Centers for Disease Control and Prevention)

Image

from article Flax

Flax plants (Linum usitatissimum) in bloom. (Photo by Howard F. Schwartz, Colorado State University)

Image

from article Flax

Flaxseeds. (Photo by Jose Hernandez, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)

Image

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)

Image

from article Flax

Blighted and moldy flaxseeds. (Photo by J. A. Hoes, Oilseed Diseases Image Collection, Western Committee on Plant Disease, Winnipeg, Manitoba, Canada)

Image

from article Peppermint

Peppermint (Mentha piperita). (Photo by Michael Thompson, Agricultural Research Service, U.S. Department of Agriculture)

Image

from article Citron

Citron (Citrus medica), including cross sections of the fruit. (Photo courtesy of California Citrus Clonal Protection Program)

Image

from article Foodborne disease

Trichrome-stained photomicrograph of a Giardia lamblia trophozoite (a growing stage in the life cycle of certain protozoan parasites). This microorganism often causes giardiasis (a diarrheal foodborne illness). (Credit: Melanie Moser/Centers for…

Image

from article Foodborne disease

A cluster of norovirus particles. (Credit: Charles D. Humphrey/Centers for Disease Control and Prevention)

Image

from article Foodborne disease

Colored scanning electron micrograph showing Salmonella enterica bacteria (serotype Typhimurium; colorized red) invading an immune cell (colorized yellow). This bacterial species commonly causes food-associated gastroenteritis. (Credit: National…

Image

from article Foodborne disease

Close-up view of Campylobacter jejuni bacteria. This scanning electron microscope image shows the characteristic spiral (or corkscrew) shape of C. jejuni cells. (Credit: De Wood and Chris Pooley/Agricultural Research Service, U.S. Department of…

Image

from article Cabbage

Cabbage (Brassica oleracea var. capitata). (Joseph Harris Co., Inc., Rochester, New York)

Image

from article Gelatin

Image

from article Gelatin

Gelatin fruit dessert. (Credit: Getty Images/iStockphoto)

Image

from article Trans fatty acid

Generalized chemical structure of the double bond in natural and common industrial monounsaturated fatty acids (18:1): configuration of the unsaturation site in monounsaturated fatty acids as found as a cis structure in natural fats/oils or as a…

Image

from article CRISPR/Cas9 gene editing

Acquisition of immunity in the CRISPR/Cas9 system. Bacterial cells that are not immune to a particular bacteriophage and that survive infection acquire immunity through the function of the cas1 and cas2 genes. Through unknown mechanisms, Cas1 and…

Image

from article CRISPR/Cas9 gene editing

The function of the CRISPR/Cas9 system in bacterial immunity. Bacterial cells that are immune to particular bacteriophage species contain protospacer sequences that match or closely match the bacteriophage genome. (1) The bacterial genome contains…

Image

from article CRISPR/Cas9 gene editing

The function of the CRISPR/Cas9 system in genome engineering. Multiple methods are used to engineer genomes using the CRISPR/Cas9 system. One common method is illustrated here. (1) An engineered cas9 gene and an engineered crRNA–tracrRNA fusion…

Image

from article Brain

Magnetic resonance imaging (MRI) is a tool used to scan the brain. Four coronal-view MRI scans of the human brain are shown. (Credit: Shutterstock/AkeSak)

Image

from article Brain

Image

from article Brain

Image

from article Vestibular system

The vestibular labyrinth is located within the inner ear. It communicates with the brain via the VIIIth nerve. Each of the three semicircular canals has an ampulla and a long and slender duct. The utricle primarily senses motion in an earth-parallel…

Image

from article Vestibular system

Ampulla of a semicircular canal. This cross section is perpendicular to the long axis of the horizontal canal. The canal hair cell stereocilia are considerably longer than their macular counterparts, averaging about 0.1 mm in length.

Image

from article Vestibular system

Otolithic macula at rest. The arrows within the primary afferents or VIIIth nerve fibers indicate spontaneous activity in these fibers in the absence of motion of the otolithic mass relative to the hair cell stereocilia. (The otolithic membrane is…

Image

from article Vestibular system

Otolithic macula being stimulated by linear acceleration or gravity in its on-direction. The stereocilia are deviated toward the longest cilium (the on-direction for the hair cells). The large arrows within the primary afferents or VIIIth nerve…

Image

from article Vestibular system

Otolithic macula being stimulated by linear acceleration or gravity in its off-direction. The stereocilia are deviated away from the longest cilium (the off-direction for the hair cells). The absence of arrows within the primary afferents or VIIIth…

Image

from article Hepatitis

False-color transmission electron microscopy image of the hepatitis A virus (HAV). (Credit: BSIP/Getty Images)

Image

from article Hepatitis

Image

from article Hepatitis

Inflammation in chronic hepatitis C virus (HCV) infection. When the body is engaged in fighting chronic inflammation of the liver's portal tract (center of the photomicrograph), lymphocytes (white blood cells) are present. (Copyright © McGraw-Hill…

Image

from article Yersinia

Scanning electron micrograph (color-enhanced) of Yersinia pestis bacteria (yellow) on the proventricular spines of a Xenopsylla cheopis flea (purple). (Photo courtesy of the National Institute of Allergy and Infectious Diseases, Bethesda, MD)

Image

from article Taste

Taste buds in a circumvallate papilla in a mouse tongue with taste cells visualized in color by cell-type-specific fluorescent antibodies. (Credit: Aki Taruno/Perelman School of Medicine, University of Pennsylvania)

Image

from article Taste

Illustration of the internal structures of a taste bud, which is composed of basal stem cells and three types of taste cells (dark, light, and intermediate). Taste cells extend from the base of the taste bud to the taste pore, where microvilli…

Image

from article Taste

Lemons and lemonade taste sour because they are very acidic and have a high concentration of hydrogen (H+) ions. (Credit: Mad Circles/Getty Images)

Image

from article Taste

Image

from article Lespedeza

Sericea lespedeza (Lespedeza cuneata). (Photo by Chuck Bargeron, University of Georgia; Bugwood.org)

Image

from article Disease

Image

from article Environmental toxicology

June 2010 Deepwater Horizon Oil Spill in the Gulf of Mexico. Containment and controlled burn. (Credit: U.S. Navy photo by Mass Communication Specialist 2nd Class Justin Stumberg)

Image

from article Hypothermia

Body heat lost with exposure to 0°C air and 10°C water. °C = (°F − 32)1.8.

Image

from article Bioacoustics, animal

Acoustic absorption loss in air and seawater as a function of frequency.

Image

from article Bioacoustics, animal

Audiogram of different animals.

Image

from article Bioacoustics, animal

Single snap of a snapping shrimp, Synalpheus parneomeris (shown in inset). (a) Waveform. Source level is sound pressure level 1 m (3.3 ft) from the source. (b) Spectrum.

Image

from article Crossing-over (genetics)

Meiotic crossing-over between two gene loci A and B on homologous chromosomes with different alleles at each locus. (a) Prior to replication. (b) After replication in premeiotic interphase. (c) Crossing-over at pachytene between nonsister chromatids…

Image

from article Crossing-over (genetics)

Molecular model of recombination, based on that of R. Holliday. Only the two recombinant chromatids are shown. (a) Two homologous nonsister chromatid DNA molecules, with gene loci ab and AB, respectively; arrows are paired nicking sites. (b) After…

Image

from article Crossing-over (genetics)

Longitudinal section of a synaptonemal complex with a recombination nodule.

Image

from article Oncolytic virotherapy

One notable experimental oncolytic virotherapy technique involves the use of a modified poliovirus (PVS-RIPO) to combat glioblastoma (a type of brain cancer). The illustration shows a hypothetical model of how PVS-RIPO destroys brain tumors.

Image

from article Plant evolution

Image

from article Plant evolution

Horsetails (genus Equisetum) are primitive vascular plants. Often referred to as living fossils, horsetails typically grow in wet areas, with whorls of needlelike branches radiating at regular intervals from a single vertical stem. (Credit: Richard…

Image

from article Plant evolution

Two ancient tree leaf fossils embedded in stone. (Credit: Wong Hock Weng/123RF)

Image

from article Proteins, evolution of

Image

from article Proteins, evolution of

Phylogeny of 20 organisms, based on differences in the amino acid sequence of cytochrome c. The minimum number of nucleotide substitutions required is shown. (After W. M. Fitch and E. Margoliash, Construction of phylogenetic trees, Science,…

Image

from article Proteins, evolution of

Phylogeny of the β-globin clusters. The maps of β-globin clusters reveal the sequence in which certain genes changed through evolutionary time. The positions of pseudogenes are shown by crosses. (After R. Lewin, Evolutionary history written in…

Image

from article Sisal

Sisal (Agave sisalana). (Photo courtesy of Peter Lapshin)

Image

from article Wool

Sheep at a research facility near Dubois, Idaho. (Photo courtesy of the Agricultural Research Service, U.S. Department of Agriculture)

Image

from article Wool

Longitudinal section of a completely developed nonmedullated wool follicle, including sebaceous and sweat glands.

Image

from article Wool

Cuticle, cortex, and medulla of a wool fiber.

Image

from article Wool

Scale formation of Delaine Merino wool fibers.

Image

from article Wool

Fine wool staples showing distinct crimp (wavy) patterns. The length shown is the minimum for each classification.

Image

from article Brazil nut

Unshelled Brazil nuts (Bertholletia excelsa). (Photo courtesy of C. E. Timothy Paine)

Image

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…

Image

from article Staining

Staining of Klebsiella bacteria using crystal violet. (Credit: Lisa Burgess/McGraw-Hill Education)

Image

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…

Image

from article Vitamin A

Summary scheme depicting the dietary uptake, metabolism, and actions of vitamin A within the body. All vitamin A must be obtained from the diet as either preformed vitamin A (primarily as retinol and retinyl esters) or provitamin A carotenoid (such…

Image

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)

Image

from article Bone disorders

A colored x-ray of the hand of a patient with severe rheumatoid arthritis in all of the fingers. (Credit: Science Photo Library/Alamy Stock Photo)

Image

from article Bone disorders

A colored X-ray of a linear displacement fracture of an ulna (forearm bone) of a man. (Credit: Puwadol Jaturawutthichai/Shutterstock)

Image

from article Bone disorders

Comparison of a healthy normal bone (left) and a bone with osteoporosis (right). Osteoporosis leads to a decrease in bone mass and density, causing bones to become weak and brittle. (Credit: Stocktrek Images/Alamy Stock Photo)

Image

from article Cowpea

Cowpea (Vigna unguiculata): pods and leaves. (Photo by Howard F. Schwartz, Colorado State University)

Image

from article Cowpea

Cowpea seeds, which are often called black-eyed peas. (Photo by Joseph Berger; Bugwood.org)

Image

from article Kumquat

Fruits and foliage of the Nagami kumquat (Fortunella margarita). (Photo by Forest and Kim Starr)

Image

from article Mulberry

White mulberry (Morus alba). (Photo courtesy of Forest and Kim Starr)

Image

from article Beech

Leaf on top of bark of American beech (Fagus grandifolia). (Photo courtesy of Robert H. Mohlenbrock, USDA–NRCS PLANTS Database)

Image

from article Beech

Beechnuts of the American beech (Fagusgrandifolia). (Photo courtesy of Steve Hurst, USDA–NRCS PLANTS Database)

Image

from article Organoid

Generation of an organoid and some of its therapeutic potential. To date, organoids can be derived from patient-derived induced pluripotent stem cells (iPSCs). Like organogenesis in vivo, organoids self-organize through cell differentiation, cell…

10 | 25 | 50 | 100 items per page

Search Site Content

Browse Articles...

Search Results

Refine this search

4,120 results

Heart-Rate Monitor

Learn more about AccessScience

Search Site Content

Refine this search

Search result paging links

4,120 results

Learn more about AccessScience

Topics