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41.
42.
朱立军 《安徽农业大学学报》2001,(3):34-35
农业产业化是一项涉及多部门、多产业、多主体的系统工程,这一系统能否高效的运作.是实施农业产业化发展战略的关键。木文通过对农业产业化运行模式和运行机制的现实分析.阐述了在新形势下如何有效建立起农业产业化的运行机制。 相似文献
43.
The population of male Kirtland's warbler (Dendroica kirtlandii) in the breeding season has averaged 206 from 1971 to 1987. The Kirtland's warbler occupies dense jack pine (Pinus banksiana) barrens from 5 to 23 years old and from 1.4 to 5.0 m high, formerly of wildfire origin. In 1984, 73% of the males censused were found in habitat naturally regenerated from wildfire or prescribed burning. The rest were in plantations (11%) or in harvested, unburned jack pine stands stocked by natural regeneration (16%). Twenty-two percent (630 of 2,886) of the Kirtland's warbler males counted in the annual censuses from 1971 through 1984 were found in 26 stands that were unburned and naturally regenerated following harvest. From 1982 to 1987, suitable regenerating areas were barely sufficient to replace currently occupied maturing stands, so population growth was impeded. Ecosystems of suitable size and regeneration characteristics (wildfire and plantation) doubled in area by 1989. In response, the population of Kirtland's warblers increased from 167 to 398 males between 1987 and 1992, but they withdrew almost entirely from the unburned, unplanted barrens by 1989 when the area of more suitable regeneration types increased. Minimum (368 males) and maximum (542 males) population estimates for 1996 were calculated based on 1984 average density (1.9 males per 40 ha) and peak population in burns (2.8 males per 40 ha). 相似文献
44.
Martin Kramer Dr. Med. Vet Martin Gerwing Dr. Med. Vet Volker Hach Dr. Med. Vet Ernst Schimke Prof. Dr. Med. Vet 《Veterinary radiology & ultrasound》1997,38(2):139-149
Sonography of the musculoskeletal system in dogs and cats was undertaken to evaluate the application of this imaging procedure in orthopedics. In most of the patients a 7,5 MHz linear transducer was used because of its flat application surface and its resolving power. The evaluation of bone by sonography is limited, but sonography can provide addition information regarding the bone surface and surrounding soft tissue. Ultrasound is valuable for assessing joint disease. Joint effusion, thickening of the joint capsule and cartilage defects can be identified sonographically. It is also possible to detect bone destruction. Instabilities are often identified with the help of a dynamic examination. Soft tissue abnormalities of the musculoskeletal system lend themselves to sonographic evaluation. Partial or complete muscles or tendon tears are able to be differentiated and the healing process can be monitored. Most of the diseases that are in the area of the biceps or the achilles tendon, such as dislocation of the tendon, old injuries with scarification, free dissecates in the tendonsheath, tendinitis and/or tendosynovitis can be differentiated by sonography. In addition, with clinical and laboratory findings, it is often possible to make a correct diagnosis with ultrasound in patients with abscesses, foreign bodies, hematomas, soft tissue tumors and lipomas. 相似文献
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46.
可持续发展类型与测度的理论探讨 总被引:2,自引:0,他引:2
可持续发展的类型划分与可持续发展的测度是可持续发展理论研究的重要内容。科学反应可持续发展的特征 ,有利于可持续发展类型划分 ,是可持续发展测度的依据和目标。本文运用人地关系协调分析法与经济分析法 ,特别是与替代弹性不变生产函数分析法 (C.E.S生产函数 )相结合 ,提出了可持续的人均国内生产总值 ,探讨了可持续发展中人文资本、自然资本相互协调、相互依存的关系特征 ,建立可持续发展测度的指标系统和可持续发展的类型体系 相似文献
47.
M. HEDDELL-COWIE 《Fisheries Management and Ecology》2005,12(2):137-142
Abstract The body mass distributions and variations in abundance of the spring and autumn catches of Atlantic salmon, Salmo salar L., were compared between fisheries above and below the confluence of the rivers Tweed and Teviot, Scotland. Significant differences between the distributions were found over three periods, one in spring and two in autumn, when salmon catches were high. Correlations were found between abundance trends for periods when distributions were similar or dissimilar. Abundance of salmon returning to the River Teviot was proportional to the main river. However, its population structure differed when abundances were high, suggesting different survival strategies. It appears that changes in the numbers returning to the river were resultant of changes in the marine rather than freshwater environment. 相似文献
48.
直接利用传递函数对分叉结构进行模态综合 总被引:1,自引:0,他引:1
建立了一种直接利用传递函数对分叉结构进行模态综合的方法。传统的方法一般都需要对大矩阵进行求逆运算,而此方法只涉及分叉结构结合部的传递函数矩阵的求逆,因此求逆计算量很小,特别是当直接采用传递函数的测量值进行模态综合时,就更体现出它的优越性。 相似文献
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50.
廉高波 《绿色中国(A版)》2005,(12):39-41
通过分析我国现阶段农村经济组织的组织模式、功能及组织连接机制,指出我国农村经济组织已形成以农户家庭经营为基础层次,以社区合作经济组织、专业合作经济组织及以“公司 农户”为典型的契约型组织分别为第二、三、四层次,效能逐级递增,各层次之间具有互动作用的组织体系。 相似文献