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排序方式: 共有117条查询结果,搜索用时 15 毫秒
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Sedimentation and resuspension processes of aquaculture biosolids (non-ingested feed and faeces) are analysed using vertically oscillating grids as a source of turbulence in fluid tanks. An oscillating grid system consists of a container in which a grid is stirred vertically generating a well-known turbulent field that is function of amplitude and frequency of oscillation, distance between grid and measurement point, and mesh spacing of the grid. The grid used in this study had a mesh spacing of 1.2 cm, and was calibrated using different amplitudes (1, 1.5 and 2 cm), frequencies (from 1 to 6 Hz) and distances (2.4, 2.7 and 3 cm). After calibration, the turbulence needed to resuspend biosolids and to maintain them in the water column following different times of consolidation, and with biosolids of different origin, was analysed. It was observed that the turbulence needed to resuspend aquaculture biosolids increased with the time of consolidation. When the turbulence was decreased after a resuspension process, the next sedimentation of biosolids showed a hysteretic behaviour: turbulence needed to resuspend a fixed percent of biosolids from the tank bottom is substantially higher than that needed to maintain the same percentage suspended in the water column. Differences in resuspension behaviour of biosolids originated in different tanks were also observed.
The method provides useful information that can be compared with turbulence generated by fish swimming activity, in order to determine the culture conditions, which can promote self-cleaning conditions in a particular tank. 相似文献
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Freshly excreted Canada goose faeces pose a public health risk as they contain pathogenic microorganisms. Accordingly, a study was carried out on the growth and survival of resident indicator bacteria (enterococci and Escherichia coli) and inoculated Campylobacter jejuni in freshly excreted faeces over summer and winter. Canada goose faeces were collected, mixed thoroughly and inoculated with 108 g?1C. jejuni. The faeces were mixed again before making the Canada goose dropping. The simulated goose droppings (N = 70) were placed on pasture, and the concentrations of E. coli, enterococci and the pathogen, C. jejuni, were monitored. In summer only, the molecular marker of E. coli LacZ and the avian‐associated bacteria E2 was also monitored. Results of the survival study indicated that significant growth of enterococci and E. coli occurred in summer, before concentrations decreased to less than 15% of the original concentration (day 77) for enterococci and 0.01% for E. coli. LacZ followed a similar pattern to E. coli, while the E2 marker dropped to below 0.1% of the original concentration within 4 days. In winter, enterococci grew slightly, while no growth of E. coli occurred. In both summer and winter, C. jejuni was rapidly inactivated. This research highlights the ability of bacterial indicators to replicate and survive in the environment when harboured by avian faeces, and the limited risk aged Canada goose faeces pose as an environmental source of Campylobacter spp. 相似文献
96.
P. Songsermsakul J. Bhm C. Aurich J. Zentek E. Razzazi‐Fazeli 《Journal of animal physiology and animal nutrition》2013,97(1):155-161
Concentration profile of zearalenone (ZON) and its metabolites in plasma, urine and faeces samples of horses fed with Fusarium toxin–contaminated oats is described. In plasma, β‐zearalenol (β‐ZOL) was detected at high levels on day 10 of the study (3.21–6.24 μg/l). β‐Zearalenol and α‐zearalenol were the major metabolites in urine. Zearalenone, α‐ZOL and β‐ZOL were predominantly found in faeces. Zearalanone could also be detected in urine (1.34–5.79 μg/l) and faeces (1 μg/kg). The degree of glucuronidation was established in all sample types, approximately 100% in urine and plasma. Low per cent of glucuronidation (4–15%) was found in faeces samples. The results indicate the main conversion of ZON into β‐ZOL in horse. This finding could explain why horse is not susceptible to ZON in comparison with swine which produce α‐ZOL as a predominant metabolite. 相似文献
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本试验采用高通量测序技术,研究饲粮中添加发酵豆粕对断奶仔猪粪便菌群多样性的影响。选取36日龄“杜×长×大”仔猪80头,随机分为A、B、C、D组,D组为对照组,饲喂基础饲粮;A、B、C组为试验组,分别在基础饲粮中添加5%、10%、15%的发酵豆粕。试验结束采集4组仔猪的粪便,采用Illumina MiSeq高通量测序技术对其中细菌的16SrRNA基因的V3~V4区序列进行测序。结果表明:1)菌群的平均有效序列数为47218条;在97%的相似水平下共产生了3581个操作分类单元(OTUs);共检测到12个门、21个纲、33个目、64个科、111个属和137个种。2)α多样性指数在各组间均无显著性差异(P>0.05),但B组的Shannon指数最高,菌群最丰富。β多样性分析表明,4组菌群在统计学上存在显著差异(P<0.05),分组效果较好。3)门水平的优势菌为厚壁菌门,科与属水平的优势菌分别为乳酸菌科和乳酸菌属。B组的厚壁菌门相对丰度显著高于D组(P<0.05),乳酸菌属相对丰度显著高于A、D组(P<0.05),但与C组间差异不显著(P>0.05)。4)菌群主要参与的代谢通路为糖类代谢、氨基酸代谢、能量代谢、核酸代谢、辅酶和维生素代谢。除核酸代谢外,其余4种代谢通路中,B组菌群的相对丰度最高并依次为C、A、D组。综上所述,在仔猪饲粮中添加10%的发酵豆粕,能增加肠道菌群的多样性,显著增加肠道中厚壁菌门、乳酸菌科和乳酸菌属等有益菌的相对丰度,维持肠道的健康,促进营养物质的代谢。 相似文献
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AbstractAIMS: To investigate the prevalence of Campylobacter spp. and C. jejuni in dog faecal material collected from dog walkways in the city of Palmerston North, New Zealand, and to characterise the C. jejuni isolates by multilocus sequence typing (MLST) and porA and flaA antigen gene typing.METHODS: A total of 355 fresh samples of dogs faeces were collected from bins provided for the disposal of dog faeces in 10 walkways in Palmerston North, New Zealand, between August 2008–July 2009. Presumptive Campylobacter colonies, cultured on modified charcoal cefoperazone deoxycholate plates, were screened for genus Campylobacter and C. jejuni by PCR. The C. jejuni isolates were subsequently characterised by MLST and porA and flaA typing, and C. jejuni sequence types (ST) were assigned.RESULTS: Of the 355 samples collected, 72 (20 (95% CI=16–25)%) were positive for Campylobacter spp. and 22 (6 (95% CI=4–9)%) were positive for C. jejuni. Of the 22 C. jejuni isolates, 19 were fully typed by MLST. Ten isolates were assigned to the clonal complex ST-45 and three to ST-52. The allelic combinations of ST-45/flaA 21/porA 44 (n=3), ST-45/flaA 22/porA 53 (n=3) and ST-52/ flaA 57/porA 905 (n=3) were most frequent.CONCLUSIONS: The successful isolation of C. jejuni from canine faecal samples collected from faecal bins provides evidence that Campylobacter spp. may survive outside the host for at least several hours despite requiring fastidious growth conditions in culture. The results show that dogs carry C. jejuni genotypes (ST-45, ST-50, ST-52 and ST-696) that have been reported in human clinical cases.CLINICAL RELEVANCE: Although these results do not provide any evidence either for the direction of infection or for dogs being a potential risk factor for human campylobacteriosis, dog owners are advised to practice good hygiene with respect to their pets to reduce potential exposure to infection. 相似文献
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A. C. Mgbeahuruike P. Nørgaard T. Eriksson M. Nordqvist 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(1):8-16
Effects of grass–clover silage (GCS) alone or combined with whole-crop cereal silage, maize silage (MS) or ensiled pressed sugar beet pulp (EPSB) on faecal characteristics and performance of early-lactation dairy cows were studied in 26 herds. Data were analysed with herd as the experimental unit and correlation coefficients among the variables were estimated. Feeding MS combined with GCS resulted in faeces of a firmer consistency (P?.05), containing more undigested fibre compared to feeding GCS alone or with EPSB (P?.05). There was a strong positive correlation between the number of grains and starch concentration in faeces (r?=?0.83, P?.001). Increasing forage dry matter (DM) intake decreased faecal DM concentration (r?=??0.54, P?.01) but seems to result in cleaner cows, whereas increasing DM intake of concentrate increased faecal DM concentration (r?=?0.63, P?.01) but might result in dirtier cows. 相似文献