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排序方式: 共有636条查询结果,搜索用时 15 毫秒
31.
The aim of this study was to evaluate the effect of leptin administration during superovulation on in vivo goat embryo production. Ten mature does were superovulated with 133 mg follicle‐stimulating hormone (FSH) i.m. in six descending doses at 12‐h intervals. The goats received 4.8 μg/kg human recombinant leptin s.c. (leptin group, n = 5) or phosphate‐buffered saline (PBS) (control group, n = 5) with the first and second FSH doses. The does were mated and subjected to embryo collection by transcervical technique 6 days later. The total number of cells per embryo and the number of cells with fragmented DNA were assessed in selected blastocysts by combining Hoechst 33342 and terminal dUTP nick‐end labelling (TUNEL) staining. Plasma concentrations of oestradiol (E2) and progesterone (P4) were determined by electrochemiluminescence from the day of FSH treatment, on the day of superovulatory oestrus and on the day before embryo collection. Compared with the control group, the does that received leptin had a higher number of transferable embryos (p < 0.005), fewer embryos classified as degenerated (p < 0.001) and fewer TUNEL‐positive cells/blastocyst (p < 0.001). The number of transferable embryos was positively correlated with E2 concentrations on day of oestrus (r = 0.562; p < 0.01) and P4 concentrations on the day of embryo collection (r = 0.912; p < 0.001). We concluded that in vivo leptin administration during FSH treatment improved embryo quality and affected ovarian steroidogenesis in superovulated goats.  相似文献   
32.
This research contrasts the financial profitability of different agroforestry practices in community-based buffer zone management of Madhupur National Park (MNP), Bangladesh. This park is the second largest in Bangladesh and subjected to enormous anthropogenic pressure and land rights-related conflicts. This paper reports the different agroforestry practices of villagers in different modules of the buffer zone of MNP, identified by a participatory research approach. It then assesses the profitability of each module on the basis of cost–benefit analysis, net present value, internal rate of return, and annualized income. Results indicate three agroforestry systems were being practised in the buffer zone by the participants: agro-silviculture, agro-silvo-horticulture, and combined woodlot and agroforestry. Among these modules, agro-silvo-horticulture was the most profitable, followed by agro-silviculture then combined woodlot and agroforestry. We recognize that not all of the participants can practise intensive agroforestry; our results suggest that the community-based buffer zone management strategy for MNP would benefit from prioritizing agroforestry practices where possible. This will lead to more successful buffer zone management for the conservation of natural forests while supporting the development of local resource-dependent communities.  相似文献   
33.
Research was conducted in Alutilla Valley in eastern Bangladesh to identify the nature of existing agroforestry systems and to identify potential agroforestry models that could ameliorate currently degrading forest resources Data were collected through farmer participatory research and a structured quarterly survey in two villages. Qualitative and supplementary quantitative analysis methods were used to assess the financial potential of agroforestry systems. Various patterns of agroforestry exist in the study site, but all have two common principles, namely ‘integration with agriculture’ and ‘multi-functionality’. Two agroforestry models suitable for adoption by farmers have been identified. Multi-strata agroforestry, based on a fruit and timber tree canopy with vegetables and tuber species in the understorey, can be practiced in the shifting cultivation fields near settlements. Fruit and timber tree-based conservation agroforestry is well suited to manage large-scale biologically depleted landscapes. Both systems yield early financial returns, facilitating the change from shifting cultivation to multi-strata agroforestry or fruit and tree-based conservation agroforestry.  相似文献   
34.
The present research investigated the effect of stocking density on pond (75 m2, depth 1.2 m) production of Nile tilapia (Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) stocked at a fixed 3:1 tilapia:prawn ratio. Three stocking densities were tried in triplicate: 20 000 ha−1 (treatment TP‐20), 30 000 ha−1 (TP‐30) and 40 000 ha−1 (TP‐40). The ponds were provided with bamboo as substrate for periphyton development. Bamboo poles (mean diameter 5.5 cm and 5.0 poles m−2) were posted vertically into pond bottoms, resulting in 60% additional substrate area in each pond. On average, 43 genera of algae and 17 genera of zooplankton were identified from pond water, whereas 42 genera of algae and six genera of microfauna were attached to bamboo substrates. No differences were observed between treatments in the ash‐free dry matter (AFDM), chlorophyll a and phaeophytin a content of periphyton (P>0.05). Survival of tilapia and prawn and individual weight gain of tilapia were lower (P<0.05) in treatment TP‐40. The net yields were higher (P<0.05) in treatments TP‐30 (2209 and 163 kg ha−1 105 day−1 of tilapia and prawn respectively) and TP‐40 (2162 and 141 kg ha−1 of tilapia and prawn respectively) than in treatment TP‐20 (1505 and 136 kg ha−1 of tilapia and prawn respectively). The net tilapia yields were quadratic correlated (R2=0.92) with fish stocking density. The cost–benefit analysis shows that the net profit margin was highest in treatment TP‐30 (69%), followed by TP‐20 (50%) and TP‐40 (44%).  相似文献   
35.
The bleached jute fabric (BJF) reinforced polypropylene (PP) composites with various contents of acrylic acid (AA)-treated BJF and un-AA-treated BJF were fabricated by compression moulding method at 190 °C. The AA-grafted BJF reinforced PP composites were then irradiated by γ-ray at various doses. The mechanical properties of neat PP (N-P), ungrafted-BJF and PP composites (UG-BJFPC), AA-grafted-BJF and PP composites (AA-BJFPC) and γ-ray cum AA-grafted-BJF and PP composites (γAA-BJFPC) show maximum tensile strength (TS) of 30, 46, 47 and 51 MPa, maximum flexural strength (FS) of 34, 49, 50 and 54 MPa and maximum Young’s modulus (E) of 280, 428, 436, and 680 MPa, respectively. The increase of TS, FS and E from UG-BJFPC are 2 %, 2 %, and 2 % for AA-BJFPC and 11 %, 10 % and 59 % for γAA-BJFPC. The TS, FS and E are found to increase with radiation dose up to 500Krad and then decrease. The water absorption (WA) for UG-BJFPC, AA-BJFPC and γAA-BJFPC is respectively about 14, 10 and 9 %, indicating a gradual development of hydrophobic character of the composites first by AA-treatment and then by γ-ray-treatment. AA treatment on jute fabric and gamma irradiation on composite result in significant change of morphology of the jute fabric composites surface and better mechanical bonding between fabric and polymer matrix, as a result improved mechanical properties are found.  相似文献   
36.
The antitumor activity of the ethanolic extracts of 12 medicinal plants of Bangladesh, including the vincristine-vinblastine producing Catharanthus roseus was studied using the potato disk bioassay technique. Among these, 10 plant extracts at 25.0-microgram/disc exhibited significant inhibition of crown gall tumors caused by Agrobacterium tumefaciens.  相似文献   
37.
Nasopharyngeal cryptococcosis   总被引:1,自引:0,他引:1  
Naturally occurring cryptococcosis in five cats, a dog and a koala is described. Involvement of the nasopharynx was documented in all patients, and nasopharyngeal mass lesions accounted for the major presenting complaints in four. Signs referable to nasopharyngeal disease included snoring, stertor, inspiratory dyspnoea and aerophagia. Diagnoses were made by caudal rhinoscopy using a retroverted flexible endoscope, vigorous orthograde flushing with saline, or at necropsy. Concurrent cryptococcal rhinitis was present in all cases, although involvement appeared limited to the caudal nasal cavity in most cases. Typical signs of nasal cavity disease, such as sneezing and nasal discharge, were often absent. Treatment of nasopharyngeal cryptococcosis should include physical dislodgement or debulking of lesion(s) to provide immediate alleviation of upper airway obstruction, followed by systemic antifungal therapy to eliminate residual infection from the nasal cavity. Infections caused by Cryptococcus neoformans var gattii accounted for a disproportionately large number of these cases.  相似文献   
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Summary The segregation and linkage between glufosinate (transgenes ‘Rf3’ and ‘T177’) and blackleg resistance genes in canola (Brassica napus L.) were assessed using F1 microspore-derived doubled haploid (DH) populations from four crosses including reciprocals, two involving the transgene ‘Rf3’ and the other two involving the transgene ‘T177’. To relax the assumption of no segregation distortion required for the conventional analysis of segregation and linkage, we employed Bailey's analysis that allows detecting segregation distortion at linked loci. The significant departures from the 1:1 segregation were detected in the crosses involving the transgene ‘T177’ but not in the crosses involving the transgene ‘Rf3’. The apparent deficit of the herbicide tolerant DH lines in the crosses with the transgene ‘T177’ is likely due to differential selection against the gametes carrying ‘T177’ during microspore culture. The linkage was strong between blackleg resistance and the transgene ‘Rf3’ but weak or absent between blackleg resistance and the transgene ‘T177’, suggesting that the two transgenes are probably inserted into distant regions of the genome. The observed linkage offers an opportunity to develop new canola cultivars with both glufosinate tolerance conferred by transgene ‘Rf3’ and blackleg resistance.  相似文献   
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