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   81篇
  免费   4篇
林业   8篇
  7篇
综合类   10篇
农作物   6篇
水产渔业   4篇
畜牧兽医   21篇
园艺   4篇
植物保护   25篇
  2022年   2篇
  2021年   1篇
  2020年   2篇
  2019年   3篇
  2017年   1篇
  2016年   9篇
  2015年   4篇
  2014年   3篇
  2013年   9篇
  2012年   6篇
  2011年   10篇
  2010年   3篇
  2009年   3篇
  2008年   4篇
  2007年   3篇
  2006年   5篇
  2005年   3篇
  2004年   5篇
  2003年   1篇
  2002年   2篇
  1998年   1篇
  1995年   1篇
  1994年   1篇
  1968年   1篇
  1954年   1篇
  1952年   1篇
排序方式: 共有85条查询结果,搜索用时 54 毫秒
1.
Blood transfusions in veterinary medicine have become increasingly more common and are now an integral part of lifesaving and advanced treatment in small and large animals. Important risks associated with transfusion of blood products include the transmission of various infectious diseases. Several guidelines suggest what infectious agents to screen for in canine and feline transfusion medicine. However, while the risk of bacterial contamination of blood products during storage and administration has not been documented in veterinary medicine, it has emerged as a cause of morbidity and mortality in human transfusion medicine. Clinical experience shows that the majority of blood component bacterial contaminations are caused by only a few species. Unlike other types of bacteria, psychrotolerant species like Pseudomonas spp. and Serratia spp. can proliferate during the storage of blood units at 4°C from a very low titer at the time of blood collection to a clinically significant level (> 105 CFU/mL) causing clinical sepsis resulting from red blood cell concentrate transfusions in human medicine. The purpose of this report was to describe the detection and quantification procedures applied in 4 cases of bacterial contamination of canine and feline blood units, which suggest the need for further investigations to optimize patients’ safety in veterinary transfusion medicine.  相似文献   
2.
The combination of (1)H NMR fingerprinting of lipids from gilthead sea bream (Sparus aurata) with nonsupervised and supervised multivariate analysis was applied to differentiate wild and farmed fish and to classify farmed specimen according to their areas of production belonging to the Mediterranean basin. Principal component analysis (PCA) applied on processed (1)H NMR profiles made a clear distinction between wild and farmed samples. Linear discriminant analysis (LDA) allowed classification of samples according to the geographic origin, as well as for the wild and farmed status using both PCA scores and NMR data as variables. Variable selection for LDA was achieved with forward selection (stepwise) with a predefined 5% error level. The methods allowed the classification of 100% of the samples according to their wild and farmed status and 85-97% to geographic origin. Probabilistic neural network (PNN) analyses provided complementary means for the successful discrimination among classes investigated.  相似文献   
3.
An eight-week experiment was carried out to evaluate the effects of different protein sources (fish and haemoglobin meal, soybean meal and torula yeast), in practical diets, on growth, body composition and gut morphology of fingerling grey mullet (Mugil cephalus). Weight gain (%), SGR, FCR, N retention, PER, PGR, FDR and carcass composition of fish were not significantly affected by the dietary protein source. Fish fed the torula yeast based diet showed reduction in growth performance. Histological examinations performed on the alimentary tract of the fish showed a normal structural pattern in the experimental groups, as fundamental histological and histochemical aspects were similar if compared to the control group. The lower growth performance observed in fish fed a torula yeast based diet may be tentatively correlated with the presence of some detrimental morpho-functional aspects in the gut of these fish if compared to fish fed the other diets. Further studies are necessary to confirm this hypothesis.  相似文献   
4.
The effect of finishing extensive farming period, to reduce fat content and manipulate the fatty acid profile of fish muscle, was evaluated in rainbow trout. Fish were stocked in an artificial lake, in which fish were fed only on naturally available nutrients with no supply of artificial feed, for different lengths of time from 0 to 120 days. No weight loss was noted during the whole finishing period while total length increased from 228±7 to 269±3 mm and the condition factor decreased from 1.41±0.04 to 0.89±0.02. The total fat content of the fillets decreased considerably from 4.7±0.6% at the beginning to 2.4±0.4% and 0.7±0.2% after 45 and 120 days respectively. Fillet fatty acid composition was affected by the time of stocking in the extensive farm. In contrast to the reduction in C18:1n‐9, C18:2n‐6, total monounsaturated fatty acid and total n‐6 percent values, an increase in the C20:5n‐3, C22:6n‐3, total polyunsaturated fatty acid and total n‐3 percent values was observed. It was shown that while other finishing strategies for salmonids have some disadvantages, the extensive culture system seems to be a potentially useful tool for increasing the general quality of the end product.  相似文献   
5.
6.

Background

Cultivated sunflower (Helianthus annus L.) is a globally important oilseed crop, subjected to intensive genetic and genomic studies. Although classical mutagenesis has successfully been applied to Helianthus genus in the past, we have developed the first sunflower TILLING resource.

Results

To balance the maximum mutation density with an acceptable plant survival rate, a 'kill curve' analysis was first conducted with different ethylmethanesulfonate (EMS) dosages and different exposure times. According to the germination rate, a treatment with 0.7% EMS for 6 h was chosen. An M2 progeny of 3,651 fertile plants was obtained. Totally, 4.79% of the whole population showed clear aberrant phenotypes. A microsatellite analysis on a representative sample of the original seed stock and mutant lines confirmed the uniformity of the genetic background of plant material. The TILLING procedure was successfully applied to sunflower genome, initially by a CelI-nuclease mismatch cleavage assay coupled with a DNA-pooling level test. To investigate the efficiency of the mutagenic treatment, a pilot screening was carried out on 1,152 M2 lines focusing on four genes, three involved in the fatty acid biosynthetic pathway and one for downy mildew resistance. A total of 9 mutant lines were identified and confirmed by sequencing; thereby, the estimated overall mutation frequency for the pilot assay resulted to be 1/475 kb.

Conclusion

A first TILLING population for a high throughput identification of EMS-induced point mutations in sunflower genome has been successfully obtained. This represents a powerful tool to a better understanding of gene function in sunflower.  相似文献   
7.
Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.  相似文献   
8.
Rossi V  Caffi T 《Phytopathology》2012,102(2):158-165
Although primary infection of grapevines by Plasmopara viticola requires splash dispersal of inoculum from soil to leaves, little is known about the role of rain in primary inoculum dispersal. Distribution of rain splashes from soil to grapevine canopy was evaluated over 20 rain periods (0.2 to 64.2 mm of rain) with splash samplers placed within the canopy. Samplers at 40, 80, and 140 cm above the soil caught 4.4, 0.03, and 0.003 drops/cm(2) of sampler area, respectively. Drops caught at 40 and 80 cm (1.5 cm in diameter) were larger than drops at 140 cm (1.3 cm). Leaf coverage by splashed drops, total drop number, and drop size increased with an increase in the maximum intensity of rain (mm/h) during any rain period. Any rainfall led to infection in potted grapevines placed outside on leaf litter containing oospores, if the litter contained germinated oospores at the time of rain; infection severity was unrelated to rain amount or intensity. Results from vineyards also indicate that any rain can carry P. viticola inoculum from soil to leaves and should be considered a splash event in disease prediction systems. Sampling for early disease detection should focus on the lower canopy, where the probability of splash impact is greatest.  相似文献   
9.
Pseudomonas aeruginosa represents an opportunistic pathogen for animals and humans that is often associated with high disease morbidity and, at times, mortality. Captive reptiles have been shown to be reservoirs of P. aeruginosa strains that can be sources of exposure to humans that come in contact with these animals. In this study, the prevalence of P. aeruginosa among subclinical captive reptile species and the antimicrobial sensitivity of bacterial isolates were investigated. Sixty-five oral swabs were collected from captive reptiles belonging to 15 different species in which no overt signs of disease were evident. From this group of animals, 46 (70.8%) isolates were identified as P. aeruginosa. All of the P. aeruginosa strains were shown to have a wide range of antibiotic resistance. At present, there is a paucity of data regarding the prevalence of P. aeruginosa in various reptile species; therefore, continued scientific investigations are indicated to determine the significance of P. aeruginosa infection as it relates to captive reptile species.  相似文献   
10.

? Context

The Mediterranean Basin is a fire-prone area. Pinus halepensis Mill. is a naturally growing conifer which is frequently used for reforestation and restoration as it displays some degree of adaption to fire. One of the traits conferring tolerance to fire is the frequent presence of serotinous cones that are thought to protect seeds from fire damage.

? Aim

We checked for the physiological responses of seeds to different intensities of fire and related them to the degree of serotiny of the cones.

? Methods

Germination percentage, mean germination rate and enzymatic activity (??-amylase and protease) were recorded for seeds burned either free or enclosed in cones. We included as experimental factors the following: fire intensity, serotiny and time during which seeds were stored in cones after harvesting and germination stage.

? Results

Burned seeds (released and enclosed) developed in serotinous cones exhibited higher heat insulation. In released seeds, germination was decreasing according to increasing fire intensity, although we found differences depending on site, serotiny and time stored after harvesting. The enzymatic activity was also found to be related to serotiny and fire intensity.

? Conclusion

Serotiny is an adaptive trait increasing the tolerance to fire which should be promoted in natural and restored populations.  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