Xem 1-20 trên 2340 kết quả The plant
  • Abstract: The impact of salinity on three arboreal mangrove plants, Sonneratia apetala (Sa), S. caseolaris (Sc) and Rhizophora stylosa (Rs), was studied. The three mangrove species were treated with different salinity levels over a three-month period. The response and adaptation of these three mangrove species to salinity were shown to be different. Net photosynthesis rate, stomata conductance and transpiration rate of leaves decreased and soluble sugar content in leaves increased, with salt concentration in all three mangrove species.

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  • You have perhaps observed the regularity of arrangement in the twigs and branches of trees. Now pull up the roots of a plant, as, for example, sheep sorrel, Jimson weed, or some other plant. Note the branching of the roots. In these there is no such regularity as is seen in the twig. Trace the rootlets to their finest tips. How small, slender, and delicate they are! Still we do not see the finest of them, for in taking the plant from the ground we tore the most delicate away. In order to see the real construction of a...

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  • As I think I told you, Roger’s reaction to the “Sacrifice Photos” was even stronger and more immediate than mine.

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  • After what seems like ten weeks of unadulterated excitement—all of it the unhealthiest variety—things at Zenith House seem to have finally settled back into their accustomed drone. Porter sneaks into Jackson’s office and sniffs the seat of her office chair during the five-minute period which comes every morning between ten and ten-thirty when the seat is vacant (it is during this half-hour each morning that Ms. Jackson removes herself and a copy of either Vogue or Better Homes and Gardens to the ladies’ bog, where she has her daily dump)...

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  • There’s an old Chinese curse which goes, “May you live in interesting times.” I think it must have been especially aimed at folks who keep diaries (and if they follow Roger’s edict, that number will soon be increased by three: Bill Gelb, Sandra Jackson, and Herb “Give Me The World And Let Me Boss It” Porter). I sat here in my little home office—which is actually just a corner of the kitchen to which I have added a shelf and a bright light—pounding the keys of my typewriter for nearly five hours last night.

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  • As soon as Sandra Jackson and Dina Andrews step off the train, eleven-yearold Dina expresses her desire to go on the Wonder Wheel, which has just resumed operation for another season. On their way down there, they are huckstered cheerfully from both sides of the mostly empty midway. One cry makes Sandra smile: “Hey, pretty blonde lady! Hey, you little red-headed cutie! Come on over here and try your luck! Make my day!”

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  • Nitric oxide enhances salt secretion and Na+ sequestration in a mangrove plant, Avicennia marina, through increasing the expression of H+-ATPase and Na+/H+ antiporter under high salinity.

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  • I’ve got a case of the mean reds, so I thought I’d pass some of them on— see the enclosed Xeroxes, concluding with a typically impudent communication from Riddley, he of the coal-black skin and three hundred huge white teeth.

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  • Thermal power plants are one of the most important process industries for engineering professionals. Over the past decades, the power sector is facing a number of critical issues; however, the most fundamental challenge is meeting the growing power demand in sustainable and efficient ways. Practicing power plant engineers not only look after operation and maintenance of the plant, but, also look after range of activities including research and development, starting from power generation to environmental aspects of power plants.

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  • Ecology is the study of the relationships between an organism and its environment. The "organism" is the plant or animal that we are observing. The "environment" refers to the organism's surroundings. For example, we might be studying a cactus plant in the desert.

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  • Evidence grows daily of the rapid changes in climate due to human activities and their impact on plants and animals. Plant function is inextricably linked to climate and atmospheric carbon dioxide concentration. On the shortest and smallest scales the climate affects the plant’s immediate environment and thus directly influences physiological processes. On longer and larger time and space scales climate influ- ences species distribution and community composition and determines what crops can be viably produced in managed agricultural, horticultural and forestry ecosys- tems.

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  • First and foremost, it is a book geared towards fish aquarists. And it is a heavy read with alot of chemistry and biology. To sum up the book: the author wrote the book to bring it to the reader's attention that an aquarium is a sort of (semi)closed ecosystem, and it needs to be thought of as this in order to be successful in raising the plants and animals inside the aquarium. she then describes the biological principles behind her methods of setting up and maintaining "low-tech" planted aquariums (as opposed to hi-tech, like those of takashi amano). She uses...

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  • Salinity stress negatively impacts agricultural yield throughout the world affecting production whether it is for subsistence or economic gain. The plant response to salinity consists of numerous processes that must function in coordination to alleviate both cellular hyperosmolarity and ion disequilibrium. In addition, crop plants must be capable of satisfactory biomass production in a saline environment (yield stability).

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  • MINERAL NUTRIENTS ARE ELEMENTS acquired primarily in the form of inorganic ions from the soil. Although mineral nutrients continually cycle through all organisms, they enter the biosphere predominantly through the root systems of plants, so in a sense plants act as the “miners” of Earth’s crust (Epstein 1999). The large surface area of roots and their ability to absorb inorganic ions at low concentrations from the soil solution make mineral absorption by plants a very effective process.

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  • SURVIVAL ON LAND POSES SOME SERIOUS CHALLENGES to terrestrial plants, foremost of which is the need to acquire and retain water. In response to these environmental pressures, plants evolved roots and leaves. Roots anchor the plant and absorb water and nutrients; leaves absorb light and exchange gases. As plants increased in size, the roots and leaves became increasingly separated from each other in space. Thus, systems evolved for long-distance transport that allowed the shoot and the root to efficiently exchange products of absorption and assimilation.

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  • Abstract Physiological and biochemical responses induced by salt stress were studied in laboratory-grown young plants of the mangrove, Bruguiera gymnorrhiza. The growth rates and leaf areas were highest in the culture with 125 mM NaCl. Transpiration rates showed a diel periodicity when the plants were placed in water, but the oscillatory cycles disappeared for plants placed in higher

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  • WATER PLAYS A CRUCIAL ROLE in the life of the plant. For every gram of organic matter made by the plant, approximately 500 g of water is absorbed by the roots, transported through the plant body and lost to the atmosphere. Even slight imbalances in this flow of water can cause water deficits and severe malfunctioning of many cellular processes. Thus, every plant must delicately balance its uptake and loss of water. This balancing is a serious challenge for land plants. To carry on photosynthesis, they need to draw carbon dioxide from the atmosphere, but doing so exposes them to...

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  • All plants when carefully burned leave a portion of ash, ranging widely in quantity, averaging about 5 per cent, and often exceeding 10 per cent of the dry weight of the plant. This plant ash represents inorganic substances taken from the soil by the roots. In addition, the nitrogen of plants, averaging about 2 per cent and often amounting to 4 per cent, which, in burning, passes off in gaseous form, is also usually taken from the soil by the plant roots. A comparatively large quantity of the plant is, therefore, drawn directly from the soil. Among the ash...

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  • LIFE IN EARTH’S ATMOSPHERE presents a formidable challenge to land plants. On the one hand, the atmosphere is the source of carbon dioxide, which is needed for photosynthesis. Plants therefore need ready access to the atmosphere. On the other hand, the atmosphere is relatively dry and can dehydrate the plant. To meet the contradictory demands of maximizing carbon dioxide uptake while limiting water loss, plants have evolved adaptations to control water loss from leaves, and to replace the water lost to the atmosphere.

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  • THE FORM AND FUNCTION of multicellular organism would not be possible without efficient communication among cells, tissues, and organs. In higher plants, regulation and coordination of metabolism, growth, and morphogenesis often depend on chemical signals from one part of the plant to another. This idea originated in the nineteenth century with the German botanist Julius von Sachs (1832–1897). Sachs proposed that chemical messengers are responsible for the formation and growth of different plant organs.

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