排序方式: 共有48条查询结果,搜索用时 781 毫秒
11.
Ultrathin carbon support films for electron microscopy 总被引:1,自引:0,他引:1
Carbon support films only 4 to 6 angstroms thick have been made for use in electron microscopy. The determination of their thickness is based on geometrical calculation, electron scattering measurements, and elemental microanalysis. 相似文献
12.
Glaeser E 《Science (New York, N.Y.)》2011,333(6042):592-594
Technological changes and improved electronic communications seem, paradoxically, to be making cities more, rather than less, important. There is a strong correlation between urbanization and economic development across countries, and within-country evidence suggests that productivity rises in dense agglomerations. But urban economic advantages are often offset by the perennial urban curses of crime, congestion and contagious disease. The past history of the developed world suggests that these problems require more capable governments that use a combination of economic and engineering solutions. Though the scope of urban challenges can make remaining rural seem attractive, agrarian poverty has typically also been quite costly. 相似文献
13.
14.
Advances in fungal biosystematics and molecular genetics have clarified relationships among the wood‐decay fungi and are providing new tools for their detection and identification. Species complexes of forest pathogens, including those within Heterobasidion, Armillaria, Laetiporus, and Phellinus, are being resolved. The ability to isolate fungal DNA directly from wood without in intermediate culturing step will greatly facilitate sampling and disease detection and has applications in forest disease management, hazard tree assessment, invasive species detection, and carbon cycling, sequestration and climate change research. Recent changes in fungal nomenclature and their application to forest pathology are discussed. 相似文献
15.
DeVilbiss B Ziegler J Righter D Allen A Barrington G Haldorson G 《Journal of zoo and wildlife medicine》2011,42(3):513-517
A 2-yr-old male intact alpaca (Vicugna pacos) was admitted for a 4-day history of anorexia and colic. Five months prior, the alpaca had undergone surgical removal of a duodenal trichophytobezoar and had recovered uneventfully. The alpaca died under anesthesia, and diaphragmatic herniation of the third gastric compartment (C3) was diagnosed at necropsy. A defect was identified in the left dorsal hemidiaphragm accompanied by herniation of 80% of C3 and the aboral portion of the second gastric compartment into the pericardial sac. The smooth margins and dorsal location of the diaphragmatic defect suggested a congenital origin. Diaphragmatic herniation is uncommon in camelids, and only one other case has been reported. Due to the dorsal location of the diaphragmatic defect in this animal, positioning during the previous surgery may have initiated a partial entrapment of gastric compartments, leading to a more complete incarceration between when the animal was discharged and presented again. 相似文献
16.
Bethany DeVilbiss Dana Neelis Jennine Ochoa Jessie Ziegler George Barrington Andrew Allen 《The Canadian veterinary journal. La revue veterinaire canadienne》2013,54(10):960-964
Computed tomography was used to aid in the antemortem diagnosis of leukoencephalomyelitis in a goat infected by caprine arthritis encephalitis virus (CAEV). Imaging results were corroborated by histologic examination. This report discusses various methods of imaging the nervous system and their potential for use in the antemortem diagnosis of CAEV neurologic changes. 相似文献
17.
Rebecca Ibach Marek Gnatowski Grace Sun Jessie Glaeser Mathew Leung John Haight 《Wood material science & engineering》2018,13(2):81-96
The flexural properties of wood–plastic composite (WPC) deck boards exposed to 9.5 years of environmental decay in Hilo, Hawaii, were compared to samples exposed to moisture and decay fungi for 12 weeks in the laboratory, to establish a correlation between sample flexural properties and calculated void volume. Specimens were tested for flexural strength and modulus, both wet and dry, at 23°C and 52°C. Some specimens degenerated to only 15% of original flexural strength. UV radiation had no impact on flexural properties of field-exposed boards; loss occurred mainly on the side opposite to the sun-exposed surface. The mechanism of the aging process on colonization of WPC by fungi was examined and is consistent with development of slow crack growth in the polyethylene matrix combined with wood decay by fungi. Wood particle decay, moisture, and elevated temperature were the major factors causing composite degradation, indicated by accumulation of voids and a severe decrease in flexural properties. To simulate long-term field impact (including decay) on WPC flexural properties in the laboratory, conditioning of specimens in hot water for an extended period of time is required. Exposure to water (70°C/5 days) was adequate for simulating long-term composite exposure in Hawaii of 4?×?15?×?86 mm3 specimens. 相似文献
18.
Jessie Q. Chen Maria C. Haws Quentin S. W. Fong PingSun Leung 《Journal of the World Aquaculture Society》2017,48(6):972-980
Locally grown oysters became available in Hawai‘i in 2014, for the first time in decades. It is unclear if these bivalve shellfish will successfully infiltrate the market when imported products similar in nature have long been the only source of fresh, shell stock products. This study investigates chef preferences for oyster attributes to determine marginal willingness to pay for locally grown oysters. A survey containing a questionnaire and a choice experiment was administered to restaurant chefs throughout Hawai‘i who currently offer oysters on their menus. The study examines trade‐offs made between attributes related to price, growout site, freshness, and supply constancy, respectively. Responses were aggregated and data were fit to a random parameters logit model. Results suggest that respondents derive the most utility from oysters that are fresh, grown locally, and supplied on an as‐available basis. The least desired products are, therefore, those that are frozen, imported from foreign sources, and supplied on a set schedule. Chefs are willing to pay an additional $5.25 for one dozen oysters that are grown locally. This evidence of an existing price premium indicates that labeling local oysters as such may be a valuable marketing strategy. 相似文献
19.
20.