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排序方式: 共有785条查询结果,搜索用时 22 毫秒
191.
192.
Murray Jon Fennell Joseph T. Blackburn George Alan Whyatt James Duncan Li Bo 《Precision Agriculture》2020,21(3):473-483
Precision Agriculture - Within the agrifood sector, the production of high yields is a driver for UK orchard husbandry. Currently, orchard tree management is typically a non-discriminatory method... 相似文献
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Aggressiveness is potentiated during the production of fish of commercial interest due to the densification and confinement, and this may affect the welfare and health of these animals. We compared the effect of salinity on aggressiveness, locomotor activity and body cortisol level in matrinxã larvae (Brycon amazonicus) submitted to three experimental treatments: 0, 2 and 4 g of common salt/L. For each treatment, the larvae were collected at 24, 36, 48, 60 and 72 HAH (hours after hatching) and then transferred to 5‐L aquariums for 30 min to analyse behavioural categories. The use of common salt increased the frequency of aggressive interaction, cannibalism, mortality and locomotion in all observation periods. Body cortisol levels did not differ between treatments until 48 HAH, but showed a significant increase at 72 HAH in the 4 g salt/L. There was a positive correlation between aggressive interactions and locomotor activity. Negative correlation was observed between these parameters and cortisol up to 60 HAH; however, they were positively correlated at 72 HAH. We concluded that the use of common salt stimulates the display of aggressive behaviour and locomotor activity and that the effect of salt is dependent on the developmental phase of the larvae of B. amazonicus. 相似文献
195.
David T. Wilson Duncan Vaughan Shaun K. Wilson Carrie N. Simon Kathy Lockhart 《Fisheries Research》2008,90(1-3):86-91
The destructive and illegal practice of using chemicals (bleach, dishwashing liquid, gasoline) to catch spiny lobster (Panulirus argus) is thought to be common throughout much of the Bahamian Archipelago. Injection of a chemical irritant into a lobster den will result in either a rapid escape response or a subduing effect, both of which make it easier to capture spiny lobster. We used both laboratory and field trials to determine the efficacy of a starch-iodide swab technique to identify lobsters that had been exposed to bleach solution (NaOCl). All lobsters exposed to bleach tested positive immediately following exposure and for varying periods thereafter. No false positives were detected on control lobsters. The average length of time that bleach remained detectable on the exoskeleton was 6.2 and 9.6 h in the laboratory and field, respectively, with some individuals testing positive 12 h after exposure. The swab technique will provide fishery officers with a powerful tool to reduce or eliminate the illegal use of bleach for harvesting spiny lobster. 相似文献
196.
Iván A. Sánchez Luis Lassaletta Duncan McCollin Robert G. H. Bunce 《Agroforestry Systems》2010,78(1):13-25
In Central Spain hedgerows are an important component of the landscape although many have been lost due to landscape planning
and reallotment programmes. Loss of hedgerows can produce changes in environmental conditions that can be especially critical
in summer, corresponding with the dry period in Mediterranean ecosystems. In order to show the effects of hedgerow removal
on summer Mediterranean environmental conditions in rural landscapes, this paper describes a comparison of some key environmental
conditions between areas where hedgerows are still present, compared to areas where they have been removed. Through a two-way
ANOVA, it was found that temperatures in the hedgerows were significantly different from those in the fields, whilst air temperatures
beneath the hedgerows were lower, and steadier, than those of surrounding areas. When temperatures of the fields were compared
to those sites where hedgerows had been removed, significant differences in temperatures were detected belowground and sometimes
at soil surface level but not at higher levels. The levels of soil water content and organic carbon were higher where hedgerows
were still in place. These differences indicate potentially negative environmental impacts due to hedgerow removal. The implications
of hedgerow conservation for environmental protection and for cropland productivity are discussed. 相似文献
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Effects of ewe body condition and level of feed intake on ovarian follicle populations and ovulation rates were studied in three groups of 12 to 15 Finnish Landrace cross ewes. Ewes were fed to achieve target body condition scores of either 2.0 (low, LM) or 2.5 (moderate, MM) and then fed a complete pelleted ration for three weeks before study so that they maintained liveweight. Ewes of a third group were also fed to achieve condition scores of 2.5 and then fed ad libitum (MAL). Neither ewe body condition nor level of feed intake significantly affected either the number of large follicles (greater than or equal to 4 mm diameter) or the ovulation rate. The proportion of estrogenic follicles was lower in MM than LM ewes (0.77 vs. 0.96; P less than 0.05), but there was no difference in this proportion between MAL and MM ewes. Insulin-like growth factor-I (IGF-I) concentrations in the follicular fluid were unaffected by ewe body condition or level of feed intake despite significant treatment differences in circulating concentrations. Inhibin concentrations were higher in estrogenic follicles of LM compared with MM ewes, and this difference was reflected in circulating profiles. Treatment differences in LH profiles were not associated with any difference in follicle populations or ovulation rate. There were no consistent treatment effects on FSH concentrations. It is concluded that the roles of inhibin and IGF-I in the control of follicle development cannot be adequately assessed on the basis of circulating concentrations alone and that there is a need to measure intrafollicular hormone profiles and associated effects on follicle physiology. 相似文献
200.
Earl F. Calfee III DVM Otto I. Lanz DVM Diplomate ACVS Daniel A. Degner DVM Diplomate ACVS Steven L. Peterson DVM MS MD Diplomate ACVS Robert B. Duncan DVM PhD Diplomate ACVP Richard V. Broadstone DVM PhD Diplomate ACVA Robert A. Martin DVM Diplomate ACVS ABVP Brenda Austin BS 《Veterinary surgery : VS》2002,31(1):32-43
OBJECTIVE: To assess donor-site morbidity and survival of the rectus abdominis muscle with an overlying skin graft after free tissue transfer to a medial femorotibial defect in dogs. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Phase 1: 6 canine cadavers; phase 2: 7 adult mixed-breed dogs. METHODS: Phase 1: The rectus abdominis muscle was removed from canine cadavers, muscular and vascular dimensions were recorded, and angiography was performed. Phase 2: Muscular transfer was performed through anastomosis of the caudal epigastric artery and vein to the saphenous artery and medial saphenous vein. Transferred tissues were evaluated on postoperative days 3, 6, 10, and 13. Animals were examined daily until euthanasia between postoperative days 31 and 42. Postmortem angiograms were performed and tissues collected for histopathologic evaluation. RESULTS: Phase 1: Appropriate vascular dimensions for microvascular anastomosis were confirmed and surgical technique perfected. Phase 2: Muscular excision produced minimal donor-site morbidity. All muscles survived after microvascular transfer and angiography confirmed vascular patency. All of the skin grafts survived, with one graft undergoing partial necrosis. CONCLUSIONS: The rectus abdominis muscle can be successfully transferred to a medial femorotibial defect and can serve as a bed for acute skin grafting. No significant donor-site morbidity is associated with its removal. CLINICAL RELEVANCE: Microvascular free tissue transfer of the canine rectus abdominis muscle has not been previously described. This technique provides a new alternative for repair of appropriate wounds. Additional studies are needed to define its utility in clinical patients. 相似文献