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  • Fisheries  (14,522)
  • Cell & Developmental Biology  (5,118)
  • General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
  • Quantum optics, physics of lasers, nonlinear optics, classical optics
  • 2020-2022  (14,417)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Environmental management 7 (1983), S. 151-160 
    ISSN: 1432-1009
    Keywords: Grass carp ; Biological control ; Nuisance aquatic weeds ; Fisheries ; Aquaculture ; Reproductive requirements ; Arkansas management plan ; Sterile hybrids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grass carp (Ctenopharyngodon idella Val.) were introduced into the United States in 1963 as potential biological control agents for nuisance aquatic weeds. Since that time an oftentimes bitter controversy has raged over its effects on sportfishing, and its possible natural reproduction and naturalization in North America. This review considers the history, ecology, and present status of grass carp in the United States in light of the voluminous scientific research conducted since its importation. Particular attention is given to the role of grass carp in the fisheries management plans of Arkansas. Recent development of a sterile, triploid grass carp hybrid may lead to widespread use of grass carp to control nuisance aquatic weeds in culturally eutrophicated waters of the United States.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Environmental management 3 (1979), S. 133-144 
    ISSN: 1432-1009
    Keywords: Coastal zone Management ; Fisheries ; Marshes ; Wetlands ; Louisiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper examines causes and consequences of wetland losses in coastal Louisiana. Land loss is a cumulative impact, the result of many impacts both natural and artificial. Natural losses are caused by subsidence, decay of abandoned river deltas, waves, and storms. Artificial losses result from flood-control practices, impoundments, and dredging and subsequent erosion of artificial channels. Wetland loss also results from spoil disposal upon wetlands and land reclamation projects. Total land loss in Louisiana's coastal zone is at least 4,300 ha/year. Some wetlands are converted to spoil banks and other eco-systems so that wetland losses are probably two to three times higher. Annual wetland losses in the Barataria Bay basin are 2.6% of the wetland area. Human activities are the principal determinants of land loss. The present total wetland area directly lost because of canals may be close to 10% if spoil area is included. The interrelationship between hydrology, land, vegetation, substrate, subsidence, and sediment supply are complicated; however, hydrologic units with high canal density are generally associated with higher rates of land loss and the rate may be accelerating. Some cumulative impacts of land loss are increased saltwater intrusion, loss of capacity to buffer the impact of storms, and large additions of nutrients. One measure of the impact is that roughly $8–17 × 106 (U.S.A.) of fisheries products and services are lost annually in Louisiana. Viewed at the level of the hydrologic unit, land loss transcends differences in local vegetation, substrate, geology, and hydrology. Land management should therefore focus at that level of organization. Proper guideline recommendations require an appreciation of the long-term interrelations of the wetland estuarine system.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 2 (1977), S. 241-259 
    ISSN: 1573-5133
    Keywords: Production ; Fisheries ; Population dynamics ; Energetics ; Fishes ; Competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Production rates of seven species of fishes were determined for one year in a 0.95 ha pond. Total annual production of all fishes in the pond was 209 g m−2y−1 (after the subtraction of 16.2 g m−2y−1 of negative production). Over 90% of the production occurred in the months of June through September, with young-of-the-year fishes contributing 84% of the total. When Y of Y fishes shifted to benthic diets in the spring, the small biomass of benthos available could not sustain the large biomas of fish. Severe competition for the available food then resulted in decreased production rates for the entire fish taxocene.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 7 (1982), S. 177-180 
    ISSN: 1573-5133
    Keywords: Temperature ; Behavior ; Ecology ; Fisheries ; Fish ; Marine juveniles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Sixteen yearling winter flounder, tested individually for 3-day periods in electronic shuttleboxes, voluntarily occupied an 8–27°C range of temperature, with a modal final thermal preferendum of 18.5°C (mean 18.7°C, median 19°C, midpoint 17.5°C, s.d. 1.9°C, S k + 0.33). The locomotor activity pattern of the yearling fish in the laboratory was markedly nocturnal, with mean hourly nocturnal activity exceeding mean hourly diurnal activity by a factor of 3.4. Maximum activity occurred at 0300 EST, minimum activity at 1400 EST. While activity generally increased with temperature, a local activity minimum occurred at 18.7°C, coinciding with the 24-hour mean final thermal preferendum. Comparison of these laboratory data with previously published field data suggest that behavioral responses to temperature and light play significant roles in determining age- and size-specific differences in seasonal depth stratification and onshore-offshore distributions in this species.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 3-9 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The skin of Bagarius bagarius (Ham.) is devoid of scales but is rough due to the presence of numerous pentagonal epidermal elevations, which are separated by deep furrows at regular intervals. These elevated pentagonal regions of the epidermis are covered by dead cornified cells in the form of caps. As the old cap goes off a new one is formed by the death of the underlying epidermal cells. The middle layer of the epidermis is mainly composed of well defined polygonal cells. Their cytoplasm is granular in nature and give reactions for protein bound sulphydryl groups. The stratum germinativum is composed of two types of basal cells, the columnar cells and the spherical cells.The flask shaped mucous glands are restricted to the epidermal furrows and secrete either neutral or acidic mucopolysaccharides. Certain large specialysed granular cells are found in the epidermis which are grouped around the taste buds. These specialysed cells may be the photocytes.Two layers of the dermis can be distinguished - the relatively thin stratum laxum and the thick stratum compactum. Dermal papillae mainly support the taste buds. The pigment cells are arranged in two layers in the dermis.The subcutis is composed of loose connective tissues, richly infiltrated with the fat cells, nerves and blood capillaries.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electron microscope studies on Tylocephalum metacestodes embedded in the tissues of the oyster, Crassostrea virginica, have revealed that the tegument of the larval tapeworm is comprised of an external and an internal level which are partially separated by a basal lamina and two layers of muscles. The outer tegumentary level is comprised of an anucleate, cytoplasmic syncytium in which are embedded large and small vesicles and mitochondria. Surfacial hooks are also embedded therein. The internal level is comprised of relatively large discrete cells including mitochondria, rough endoplasmic reticulum, and large and small vesicles. These cells are intermittently connected with the external level by cytoplasmic bridges.Arising from the external level are unusual microvilli each of which terminates as a spherical vesicle. The stem of each microvillus is covered by a unit membrane which is continuous with that overlaying the body surface. In addition, each microvillus includes an external layer of medium electron density, a medial layer of intense electron density, and a core of heterogenous, medium electron density. These structures may be intertwined and bundles can be observed at the light microscope level as fibril-like projections from the parasite's body surface. One of their possible functions may be to prevent intimate contact between the encapsulating fibers of host origin and the parasite's body surface. In addition, the contraction and distention of the circular muscles result in microvillar movement which may keep the surrounding host fluids, including those of nutritional importance to the parasite, in a state of flux thus hypothetically permitting more uniform uptake.The abundance of vesicles in the syncytial external level of the tegument appears to be characteristic of the more primitive marine cestodes belonging to the orders Trypanorhyncha and Lecanicephala.
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sequential patterns of cuticle deposition and “melanization” in the imaginal cuticle of Sarcophaga argyrostoma in parts of the body darkening before or after emergence are examined on a histological basis. The patterns in the cuticles examined range from a simple absence of “melanization” to a complex of histological changes involving “melanization” and deposition. Ultrastructural changes in the post-emergent cuticle of Sarcophaga bullata during the hardening and darkening process and cuticle deposition are described.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 151-161 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Morphological study of Corynosoma hamanni (Linstow, 1892) was continued with the intention of presenting a morphological description of a single, well defined species.Sexual dimorphism is exhibited in body size, males being larger, and in body spination. Trunk spines are arranged in a pattern similar to that of Corynosoma semerme and do not extend onto the bursa as reported in the original description of C. hamanni.Two testes, located side by side, are followed by six cement glands arranged in two groups of three glands each. One group is behind each testis. Cement ducts from glands on the right side cross over Saefftigen's pouch and join to form a reservoir on the left side; ducts from cement glands on the left side fuse forming a second reservoir. The two cement reservoirs unite before emptying into the ejaculatory duct. The bursa possesses rays on its outer wall and numerous, well-developed papillae in the muscular cap.In females, a ruptured genital ligament sac is attached partially on the dorsal wall of the uterine bell and partially on a column of six cells projecting from the bell's base into its lumen. Postericrly the dorsal wall of the bell has two protruding pockets behind which occur ten cells composing the selector apparatus. Dorsal openings into the pseudocoelom occur on either side of the uterine bell. Two muscular tubes conduct eggs into the uterus. Female C. hamanni frequently form genital vestibules in which the genital pore occurs along the dorsal wall and not, as reported for some species, at the anterior tip.Eggs of C. hamanni possess four membranes rather than the previously reported three.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A seasonal study of the seminal vesicles in relation to that of the testes had been conducted in the catfish, H. fossilis. The annual reproductive cycle of the catfish has been divided into (i) Preparatory period (February-April), (ii) Prespawning period (May-June), (iii) Spawning period (July-August) and (iv) Postspawning period (September-January). Testes exhibit initiation of spermatogenesis in the mid-preparatory period, but significant increase in weight of the testes accompanied by active spermatogenesis occurs during the prespawning period. In the spawning period, the testes are maximally enlarged and their seminiferous tubules are packed with spermatozoa. Following spawning, the testes gradually regress in the postspawning period. The seminal vesicles show initiation of secretory activity during the preparatory period but their recrudescence lags behind that of the testes by about a month. The seminal vesicles attain maximum weight and secretory activity during the spawning period. Thereafter, the seminal vesicles regress precipitously and sooner than the testes.The histochemical and biochemical studies on the seminal vesicles indicate that the secretion contains mucoproteins, acid mucopolysaccharides, primary proteoses, besides traces of phospholipids and native proteins.
    Additional Material: 2 Ill.
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