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排序方式: 共有357条查询结果,搜索用时 234 毫秒
31.
Spear RC Seto E Remais J Carlton EJ Davis G Qiu D Zhou X Liang S 《Science (New York, N.Y.)》2006,314(5802):1081-3; author reply 1081-3
32.
Rattner J 《Science (New York, N.Y.)》2006,313(5791):1235
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Jankunas J Zare RN Bouakline F Althorpe SC Herráez-Aguilar D Aoiz FJ 《Science (New York, N.Y.)》2012,336(6089):1687-1690
When a hydrogen (H) atom approaches a deuterium (D(2)) molecule, the minimum-energy path is for the three nuclei to line up. Consequently, nearly collinear collisions cause HD reaction products to be backscattered with low rotational excitation, whereas more glancing collisions yield sideways-scattered HD products with higher rotational excitation. Here we report that measured cross sections for the H + D(2) → HD(v' = 4, j') + D reaction at a collision energy of 1.97 electron volts contradict this behavior. The anomalous angular distributions match closely fully quantum mechanical calculations, and for the most part quasiclassical trajectory calculations. As the energy available in product recoil is reduced, a rotational barrier to reaction cuts off contributions from glancing collisions, causing high-j' HD products to become backward scattered. 相似文献
34.
The study of alternatives to conventional industrial agricultural production has intensified in recent years. While many types
of alternative production systems, and the motivations of individuals to participate in them, have been studied, there are
significant gaps in the literature. One such dearth is research on those participating in self-provisioning activities. This
study begins to fill the gap by looking at the self-provisioning activity of home gardening using data from the 2008 Ohio
Survey of Food, Agriculture, and Environmental Issues. Discerning who household gardeners are is important given the recent
economic, cultural, and political climate of the United States. The results show that home gardening occurs throughout the
state of Ohio at surprisingly high levels. Bivariate and multivariate analyses reveal several noteworthy associations between
gardening and household characteristics, including spatial location, pro-environmental and economic hardship behaviors, and
level of participation in localized food systems. 相似文献
35.
Justin L. Voge A. Kendrick Sudderth Steven P. Brinsko Patrick J. Burns Terry L. Blanchard 《Journal of Equine Veterinary Science》2012
Between February 15 and May 17, 2011, a total of 88 broodmares (10 maiden, 10 barren, and 68 foaling) maintained on pasture in southeast Texas were examined three times weekly (Tuesday, Thursday, Saturday) by transrectal palpation and ultrasonography. On Tuesday or Thursday, mares in estrus with uterine edema, a relaxed cervix, and a dominant follicle ≥34 mm in diameter were alternately assigned to treatment with the following: group (1) 2,500-unit human chorionic gonadotropin (hCG), intravenous; group (2) 1.0-mg BioRelease Histrelin (Biorelease Technologies, Lexington, KY), intramuscular; or group (3) 0.5-mg BioRelease Histrelin, intramuscular. Ovulation was confirmed by ultrasonographic examination. The percentage of mares ovulating within 2 days appeared to be similar between maiden, barren, and foaling mares, so responses for all mares were totaled for analysis. A nonsignificant trend for higher ovulation rates within 2 days was noted for both dose rates of histrelin compared with hCG treatment (31/37, 84%; 34/37, 92%; and 33/36, 92% for groups 1-3, respectively) (P = .45). Ovulatory responses appeared to improve for both products as the season progressed, yet no differences were detected between response rates to histrelin or hCG for any month (P ≥ .50). The use of 1.0- or 0.5-mg BioRelease Histrelin was found to be at least equally effective as hCG treatment for inducing ovulation within 2 days of treatment throughout the breeding season. 相似文献
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Schlanser JR Patterson JS Kiupel M Hencken C Sikarskie JG Harrison TM 《Journal of zoo and wildlife medicine》2012,43(2):407-411
A 21-yr-old male North American river otter (Lontra canadensis) with a chronic history of degenerative osteoarthritis was evaluated for acute posterior paralysis. Because no definitive cause was identified and a poor prognosis was expected, the otter was euthanatized. A malignant neoplasm of adrenal gland origin with disseminated metastases to the central nervous system, lymph nodes, diaphragm, pancreas, spleen, and liver was diagnosed on postmortem examination. No clinical signs of disseminated neoplasia had been noted throughout the otter's history. The adrenal neoplasm was composed of nests of epithelial cells surrounded by a fine fibrovascular stroma. Neoplastic cells were immunohistochemically positive for chromogranin A, PGP9.5, metencephalin, and endorphin and negative for melan A and inhibin, confirming a diagnosis of a malignant pheochromocytoma. On the basis of the necropsy finding, metastasis of the pheochromocytoma might have contributed to the observed clinical signs. 相似文献
38.
Justin Neu Stephen Demarais Andrew W. Ezell Samuel K. Riffell T. Bently Wigley 《Journal of Sustainable Forestry》2013,32(2):152-172
Information regarding how site preparation techniques affect residual woody structure is lacking for the southern United States in spite of the importance of such structure for many wildlife species. Therefore, we documented retained structure in young loblolly pine (Pinus taeda L.) plantations established using four common site preparation regimes: mechanical only, chemical only, chemical + mechanical, or chemical + prescribed burning. Herbicides reduced live tree density and increased snag density relative to mechanical methods. Prescribed burning reduced density of coarse woody debris (CWD) along with density and volume of piled CWD relative to chemical and mechanical methods. Our results provide a baseline for further studies of wildlife and retained structure in southern pine forests. 相似文献
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