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排序方式: 共有102条查询结果,搜索用时 15 毫秒
51.
David J Hughes Jonathan S West Simon D Atkins Peter Gladders Michael J Jeger Bruce DL Fitt 《Pest management science》2011,67(9):1082-1092
BACKGROUND: The UK government has published plans to reduce UK agriculture's greenhouse gas (GHG) emissions. At the same time, the goal of global food security requires an increase in arable crop yields. Foliar disease control measures such as fungicides have an important role in meeting both objectives. RESULTS: It is estimated that UK winter barley production is associated with GHG emissions of 2770 kg CO2 eq. ha?1 of crop and 355 kg CO2 eq. t?1 of grain. Foliar disease control by fungicides is associated with decreases in GHG emissions of 42–60 kg CO2 eq. t?1 in UK winter barley and 29–39 kg CO2 eq. t?1 in UK spring barley. The sensitivity of these results to the impact of disease control on yield and to variant GHG emissions assumptions is presented. Fungicide treatment of the major UK arable crops is estimated to have directly decreased UK GHG emissions by over 1.5 Mt CO2 eq. in 2009. CONCLUSION: Crop disease control measures such as fungicide treatment reduce the GHG emissions associated with producing a tonne of grain. As national demand for food increases, greater yields as a result of disease control also decrease the need to convert land from non‐arable to arable use, which further mitigates GHG emissions. Copyright © 2011 Society of Chemical Industry 相似文献
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Vascular permeability factor, an endothelial cell mitogen related to PDGF 总被引:159,自引:0,他引:159
P J Keck S D Hauser G Krivi K Sanzo T Warren J Feder D T Connolly 《Science (New York, N.Y.)》1989,246(4935):1309-1312
Vascular permeability factor (VPF) is a 40-kilodalton disulfide-linked dimeric glycoprotein that is active in increasing blood vessel permeability, endothelial cell growth, and angiogenesis. These properties suggest that the expression of VPF by tumor cells could contribute to the increased neovascularization and vessel permeability that are associated with tumor vasculature. The cDNA sequence of VPF from human U937 cells was shown to code for a 189-amino acid polypeptide that is similar in structure to the B chain of platelet-derived growth factor (PDGF-B) and other PDGF-B-related proteins. The overall identity with PDGF-B is 18%. However, all eight of the cysteines in PDGF-B were found to be conserved in human VPF, an indication that the folding of the two proteins is probably similar. Clusters of basic amino acids in the COOH-terminal halves of human VPF and PDGF-B are also prevalent. Thus, VPF appears to be related to the PDGF/v-sis family of proteins. 相似文献
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McCorkle R Angilello J Coleman G Feder R LA Placa SJ 《Science (New York, N.Y.)》1979,205(4404):401-402
Soft x-ray contact microscopy, utilizing single-shot exposures of approximately 60 nanoseconds duration in polymethyl methacrylate, has been realized with a resolution of 300 angstroms. The radiation spectrum is intense in the "window" between 23 and 44 angstroms where water is transparent compared to biological materials, and therefore permits viewing of wet samples. 相似文献
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AIM: To investigate the anthelmintic properties of New Zealand native flax (Phormium tenax) for cattle, using a faecal egg count reduction test (FECRT). METHODS: Twenty-six heifer calves with high (>300 epg) faecal nematode egg counts (FEC) were paired into two groups and fed either chopped flax leaves ad libitum, or barley straw at an equivalent dry matter (DM) rate, from Day 0–7; all were supplemented with 1.5 kg/head/day cereal feed supplement. On Days 8–10, all heifers were fed a common diet of 3.5 kg DM/ head/day barley straw and 1.5 kg/head/day cereal feed supplement. Heifers were weighed and faecal samples were collected on Days —6, 0, 7, and 10; samples were analysed in triplicate for FEC. The nutritive value of the flax and straw was analysed. RESULTS: Both the flax and straw had low dry matter digestibility (DMD) and protein content. Although the flax-fed claves grew more than the controls, this may have been related to gut fill. Total daily faecal egg output was similar for flax and straw groups on Day 7 (14.7 vs 15.0 x 106 eggs/day, respectively) and Day 10 (14.9 vs 15.1 x 106 eggs/day, respectively). There was no difference in the change in FEC with time between the calves fed flax or straw diets. CONCLUSION: Consumption of flax leaves did not reduce FEC in calves with a mixed nematode infection. 相似文献
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Greasy wool production, body weight, behaviour and fertility of male, fine wool Merino sheep were studied from 10 to 21 months of age to assess their suitability for wool production. The males were either castrated (wethers), or were hemi-castrated with a vasectomy and reduction (either partially or in full) of the parenchyma of the retained testicle, or the testicles pushed up into the ingulnal canal and the scrotum shortened (induced cryptorchids). There were significant differences among all groups in body weight, with increases being associated with the larger amounts of testicular tissue present. Fertility was low in the induced cryptorchids at 19 months of age. The hemi-castrates with reduced testicular parenchyma were infertile. The hemi-castrates with reduced testicular parenchyma had significantly heavier greasy fleece weights than the wethers and induced cryptorchids, which had similar fleece weights. The wether group suffered a higher prevalence of posthitis in spring and autumn than the hemi-castrate or induced cryptorchid groups. Those hemi-castrates with the largest amount of testicular parenchyma retained and the induced cryptorchids exhibited masculine behaviour patterns and had an increased incidence of fly strike to the head. The principle of hemi-castration and reduction of the testicular parenchyma is shown to be applicable in wool producing flocks with the potential to increase greasy wool production while minimising the management and marketing limitations previously associated with induced cryptorchids. 相似文献
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