首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16篇
  免费   2篇
农学   1篇
  7篇
农作物   1篇
水产渔业   2篇
畜牧兽医   6篇
植物保护   1篇
  2021年   1篇
  2020年   1篇
  2019年   3篇
  2018年   2篇
  2017年   1篇
  2015年   3篇
  2013年   1篇
  2010年   1篇
  2008年   2篇
  1999年   1篇
  1997年   1篇
  1981年   1篇
排序方式: 共有18条查询结果,搜索用时 15 毫秒
1.
Recent studies have demonstrated a strong relationship between the intestinal microbiota and the host health. As such, consumers are increasingly becoming more concerned about the potential effect of certain foods/feeds, particularly of transgenic origin on the gut microbiota. Although the European Food Safety Authority has recommended in their guidelines, to study the effect of transgenic food/feed on host-microbiota, yet, few studies have focused on the evaluation of such effects mainly due to culturing difficulties. Therefore, this study was intended to evaluate the potential adverse effects of transgenic diet consumption on some specific gut microflora (Lactobacillus group, Bifidobacterium genus, Escherichia coli subgroup and Enterococcus genus) of rabbits. A total of forty-eight rabbits were randomly assigned into four groups and fed a diet containing a variable proportion of transgenic cottonseeds at 0, 20, 30 and 40% inclusion level, respectively. Changes in the specific or total faecal bacterial population were monitored at five different experimental stages (i.e. 0, 45, 90, 135 and 180 days) using both the traditional plate count method (TM) and quantitative real-time PCR (qPCR). No significant differences (p > .05) were observed concerning numbers of specific bacteria or total bacteria between the control and experimental groups, though qPCR showed numerically higher values in terms of 16S rRNA gene copies as compared to the values obtained from TM. However, such numerical differences were biologically insignificant (p > .05). Similarly, no significant variations were noticed in the calculated B/E (log10 copies of Bifidobacterium per g faces/log10 copies of E. coli genome per g faeces) ratios in all the groups. All the ratios were in the range of 1.24 to 1.30 throughout the experiment, indicating a good balance of intestinal microflora and greater resistance to intestinal disorders. It is therefore concluded that feeding transgenic cottonseeds could not adversely affect the gut microflora of rabbits during a long-term study.  相似文献   
2.
Abstract This study was conducted to evaluate the effects of stocking density and monosex culture on growth, survival, yield and feed conversion ratio of freshwater prawn Macrobrachium rosenbergii in concrete tanks. Juvenile prawns with an average weight of 1.8 g were stocked into triplicate tanks at densities of 5, 10, 15 and 20 prawns/m2, grown for 168 d and fed a 34% tilapia diet. Stocking density had significant effect on prawns. Final mean body weight decreased with the increasing density, being highest at 5 prawns/m2 (29.6 9). and lowest at 20 prawns/m2 (17.4 g). Total yield increased from 135 g/m2 (1,350 kg/ha) at a density of 5 prawns/m2 to 261 g/m2 (2,610 kg/ha) at density 15/mz to 245 g/m2 (2,450 kg/ha) at 20/mz. Feed conversion ratios were high and ranged from 3.7 (5 prawns/m2) to 5.6 (20 prawns/m2).
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m2 for 112 d, the all-male population had the best growth performance and feed conversion ratio, followed by the mixed-sex and all-female populations. The all-male population had 99% marketable prawns (>20 g) with an average yield of 159 g/m2 (1,590 kg/ha); the mixed-sex population had 90% marketable prawns and the yield was 135 g/mz (1,350 kg/ha); and the all-female population had 75% marketable prawns with an average yield of 108 g/m2 (1,080 kgha).  相似文献   
3.
Peroxidase from fenugreek (Trigonella foenum-graecum) seeds was highly effective in the decolorization of textile effluent. Effluent was recalcitrant to the action of fenugreek seeds peroxidase (FSP). However, in order to effectively decolorize effluent by peroxidase, the role of six redox mediators has been investigated. The maximum decolorization of textile effluent was observed in the presence of 1.0 mM 1-hydroxybenzotrizole, 0.7 mM H2O2, and 0.4 U ml?1 of FSP in the buffer of pH 5.0 at 40°C in 2.5 h. The decolorization of textile effluent in a batch process by peroxidase was 85% in 5 h, whereas the complete decolorization of textile effluent by membrane-entrapped FSP was observed within 11 h of its operation. The absorption spectra of treated effluent exhibited a marked diminution in the absorbance at different wavelengths compared to untreated effluent.  相似文献   
4.
Irrigation of arable land with contaminated sewage waters leads to the accumulation of trace metals in soils with subsequent phyto‐/zootoxic consequences. In this study, biochar derived from cotton sticks was used to amend an agricultural silt‐loam soil that had been previously irrigated with trace metal contaminated sewage waters. Metal accumulation and toxicity to spinach (Spinacia oleracea) and fenugreek (Trigonella corniculata) was investigated by measuring concentrations of Cd and Ni in plant tissues and various photosynthetic and biochemical activities of plants. Positive impacts of biochar on both spinach and fenugreek were observed in terms of biomass production that increased from 29% to 36% in case of spinach, while for fenugreek this increase was 32% to 36%. In the control treatment there was an increase in malondialdihyde, soluble sugar, and ascorbic acid contents, indicating heavy metal stress. Biochar applications increased soluble proteins and amino acids in plants and reduced the uptake of Cd from 5.42 mg kg?1 at control to 3.45 mg kg?1 at 5% biochar amended soil and Ni (13.8 mg kg?1 to 7.3 mg kg?1 at 5% biochar) by the spinach plants. In fenugreek, the Cd was reduced from 7.72 mg kg?1 to 3.88 mg kg?1 and reduction in Ni was from 15.45 mg kg?1 to 9.46 mg kg?1 at 5% biochar treated soil, reducing the possibility of transfer up the food chain. This study demonstrates that the use of biochar made from cotton‐sticks, as an amendment to arable soils that have received contaminated irrigation water, could improve plant growth and decrease Cd and Ni uptake to crops, alleviating some of the negative impacts of using sewage waters on arable land.  相似文献   
5.
Assessment on the development and survival of Haemonchus contortus larvae was made to evaluate the influence of microclimatic variables viz., relative humidity (%), temperature (°C), rainfall (mm) and intensity of sunlight (hrs). Pasture plots in a sub-tropical area, Pakistan were contaminated with H. contortus eggs at the start of every month. The plots were sampled on fortnightly basis after contamination for three consecutive months. The overall pattern indicated the most favorable conditions for survival, development and translation to herbage was during the wet season from July to October and the least favorable was during the dry season from April to June. Peak infective larvae (L3) recovery was during the 15–45 day interval for each plot and the lowest number was during the 75–90 day interval. Herbage was collected in the morning, afternoon and evening and greatest recovery of L3 was in the morning time and least in the afternoon. The number of L3 on pasture was directly related to the pattern of rainfall and relative humidity with a significant (P < 0.05) positive correlation and temperature and intensity of sunshine were negatively correlated (P < 0.05). The results suggest that pastures can remain infective for up to 2 months and become relatively clean by 90 days after contamination. Thus, long pasture rest periods, especially during the high risk wet season, may be a helpful strategy to reduce the infection levels.  相似文献   
6.
A local isolate of Metarhizium anisopliae (Hypocreales: Clavicipitaceae), Bacillus thuringiensis subsp. kurstaki and chlorantraniliprole were assessed against six field populations of tomato fruitworm Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) in a series of laboratory bioassays. Two dose rates of B. thuringiensis (0.5, 1 μg g?1), one of both M. anisopliae (1.3?×?106 conidia ml?1) and chlorantraniliprole (0.01 ppm) were applied alone and in combination with each other against 2nd, 3rd, 4th and 5th larval instars. The mortality was observed every 24 h until pupation. The bioassays were carried out at 25°C and 75% r.h. The highest mortality was observed in Rawalpindi with the lowest pupation rate by applying the combined concentrations of B. thuringiensis and chlorantraniliprole. The lowest mortality was observed in population from Gujranwala among all the tested populations. The antagonistic interaction was noted where the high dose rate of B. thuringiensis was combined with M. anisopliae; however, the remaining interactions enhanced the mortality and reduced the percent pupation. The overall results demonstrated that all the treatments gave significant control of the larval instars of H. armigera. The population from Gujranwala proved least susceptible whereas the one from Rawalpindi was highly susceptible.  相似文献   
7.
Various feeding studies have been conducted with the different species of animals to evaluate the possible transfer of transgenic DNA (tDNA) from genetically modified (GM) feed into the animal tissues. However, the conclusions drawn from most of such studies are sometimes controversial. Thus, in the present study, an attempt has been made to evaluate the fate of tDNA in rabbits raised on GM cotton-based diet through PCR analysis of the DNA extracted specifically from blood, liver, kidney, heart and intestine (jejunum). A total of 48 rabbits were fed a mixed diet consisting variable proportions of transgenic cottonseeds meal (i.e. 0% w/w, 20% w/w, 30% w/w and 40% w/w) for 180 days. The presence of transgenic DNA fragments (Cry1Ac, Cry2A and CP4 EPSPS) or plant endogenous gene (Sad1) was traced in those specific tissues and organs. The presence of β-actin (ACTB) was also monitored as an internal control. Neither the transgenic fragments (459 bp of Cry1Ac gene, 167 bp of Cry2A gene and111 bp of CP4 EPSPS gene) nor cotton endogenous reference gene (155 bp of Sad1) could be detected in any of the DNA samples extracted from the rabbit's tissues in both control and transgenic groups. However, 155 bp fragment of the rabbit's reference gene (ACTB) was recovered in all the DNA samples extracted from rabbit tissues. The results obtained from this study revealed that both plant endogenous and transgenic DNA fragments have same fate in rabbit's tissues and were efficiently degraded in the gastrointestinal tract (GIT).  相似文献   
8.
The surface-running arthropods of a plantation (9·3 ha) of pine were sampled over two years. The activity of Formica lugubris was concentrated in an ‘ant-rich’ area within 40 m of its nests. There were fewer Araneae, Coleoptera, Collembola Arthropleona, Myriapoda and larval Diptera, but more Hymenoptera (ants apart), Symphypleona and Acarina in the ant-rich area than outside it. The numbers of Opiliones, Diptera, Chelonethi and larval Coleoptera did not differ. Some individual species of Araneae and Opiliones showed other differences in numbers in the two areas and were not consistent in the two years. Faunal diversity (Shannon-Wiener Index) was not less in the ant-rich area. This suggests that the encouragement or introduction of F. rufa-group ants to control forest pests would not have an adverse effect on the fauna in general.  相似文献   
9.
The aim of this study was to determine the effect of breeding method and season on pregnancy rate and cumulative embryonic and fetal losses in Nili-Ravi buffalo. Estrus detection was performed twice a day by teaser buffalo bull for 1 hour each. A 2?×?2 factorial design was used to address the breeding method and season. Buffaloes (n?=?130) exhibiting estrus were randomly assigned to be bred either in peak breeding season (PBS; n?=?80) or low breeding season (LBS; n?=?50). Within each season, buffaloes were divided to receive either natural service (NS; n?=?65) or artificial insemination (AI; n?=?65). NS buffaloes, in estrus, were allowed to remain with the bull until mating. AI was achieved, using frozen thawed semen of bull of known fertility. PBS comprised of September to December and LBS were from May to July. Serial ultrasonography was performed on days 30, 45, 60, and 90 after breeding (day 0) to monitor pregnancy rate and embryonic and fetal losses. The pregnancy rate on day 30 after breeding was higher in NS as compared to AI group (63 vs. 43%; P?<?0.05) during PBS while it did not differ (48 vs. 32%; P?>?0.05) in LBS. The cumulative embryonic and fetal losses between days 31 and 90 were significantly lower in PBS than LBS (33 vs. 60%; P?<?0.05), ignoring breeding method. Pregnancy rates were better with NS in PBS, and cumulative embryonic fetal losses were higher in LBS in Nili-Ravi buffalo.  相似文献   
10.
Plant hormones are considered to play an important role in plant adaptation to drought and salt stress. The objective of the study was to investigate the changes in endogenous jasmonic acid (JA) in relation to differences in the salt resistance of maize genotypes. Two maize genotypes (SR 03 and Across 8023) were compared for changes in water relations, growth and tissue JA levels in response to 100 mm NaCl. Salt stress significantly reduced the shoot growth of both genotypes; however, SR 03 exhibited significantly less reduction in relative shoot fresh weight than Across 8023. Both genotypes showed an identical response to salt stress regarding plant water relations; therefore, genotypic differences in the salt resistance could not be attributed to changes in shoot turgor and these results were further confirmed by the response of both genotypes under equiosmotic stress (?0.49 MPa) of either 100 mm NaCl or PEG‐6000. GC‐MS/MS analysis showed that salt stress did not alter shoot JA levels of both genotypes, however significantly increased the root JA levels of Across 8023. In contrast, root JA levels of salt‐resistant SR 03 did not change by salt stress. Increase in root JA levels in response to stress treatments does not coincide with the growth inhibition of shoot in Across 8023. In contrast, both PEG and NaCl did not change the JA concentrations in both root and shoot tissues of SR 03. Growth assays with maize seedlings showed that JA supply in root medium inhibits shoot extension growth and both maize genotypes were sensitive to the inhibitory effects of JA. These results suggest that maize genotypes differ in JA accumulation during the first phase of salt stress and JA may indirectly be involved in leaf growth inhibition of the salt‐sensitive genotype. In addition, our results also showed that treatment of salt‐stressed plants with exogenous JA improved the Na+ exclusion by decreasing the Na+ uptake at the root surface.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号