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   57篇
  免费   1篇
林业   17篇
农学   2篇
  15篇
综合类   4篇
农作物   1篇
水产渔业   3篇
畜牧兽医   13篇
园艺   1篇
植物保护   2篇
  2022年   1篇
  2021年   1篇
  2020年   4篇
  2019年   1篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   4篇
  2012年   3篇
  2011年   8篇
  2010年   2篇
  2009年   4篇
  2008年   4篇
  2007年   4篇
  2006年   1篇
  2005年   3篇
  2004年   5篇
  2003年   3篇
  2002年   2篇
  2001年   3篇
  2000年   1篇
排序方式: 共有58条查询结果,搜索用时 125 毫秒
11.
Canine idiopathic pulmonary fibrosis is a chronic, progressive interstitial lung disease particularly prevalent in West Highland White Terriers. In the present prospective pilot study, we evaluated the feasibility of modified VetMousetrap? device in high resolution CT to detect idiopathic pulmonary fibrosis in West Highland White Terriers. Twelve awake West Highland White Terriers with canine idiopathic pulmonary fibrosis and 24 clinically healthy West Highland White Terriers were scanned using a helical dual slice scanner utilizing VetMousetrap? device without or with minimal chemical restraint with butorphanol. Three evaluators blindly assessed the images for image quality and the presence of canine idiopathic pulmonary fibrosis related imaging findings such as ground glass opacity and reticular opacities. Additionally, the attenuation of the lung was quantified with ImageJ software using histogram analysis of density over the lung fields. Computed tomography was successfully completed and motion artifact ranked in statistical analysis barely noticeable to mild in all dogs. The agreement between imaging findings and clinical status was very good with overall κ value 0.91 and percentage of agreement of 94%. There was also very good intraobserver (κrange = 0.79‐0.91) and interobserver agreement (κ = 0.94). Moderate to severe ground glass opacity was present in all affected dogs. In the ImageJ analysis, a significant difference in lung attenuation between the study groups was observed. We conclude that modified VetMousetrap? device is applicable in diagnosing canine idiopathic pulmonary fibrosis in awake West Highland White Terriers avoiding anesthetic risk in these often severely hypoxic patients.  相似文献   
12.
Allium siculum Ucria is a perennial bulbous plant that occurs in Bulgaria as A. siculum subsp. dioscoridis (Sm.) K. Richt. The plant is locally known as “samardala”. Its herbage is used traditionally by local communities in Bulgaria as edible green and for preparation of salty spice mixtures. The study was focused on the documentation of traditional knowledge about samardala, covering local collection and cultivation practices, processing methods and consumption preferences. The respondents (aged 30–86 years, 50% over 65) were local producers and small-scale salesmen of the herbage and samardala-containing spices. To assess the health features of samardala spices the total phenol and flavonoid content was measured in home-consumed or marketed flavoured salts. Overall appreciation of the plant and related food products was found to be very high; presenting a considerable engagement of the locals in plant cultivation and gathering, laborious processing and consumption. Traditional ecological knowledge about the biology, phenology and ecology of the samardala plant and methods for its processing is still preserved by elderly people who rely mostly on their own cultivated plants. Although the introduction of modern appliances has altered the method of production, its main stages and the recipes are preserved. Modernization of the processing method has not affected the quality of the products and faster processing could be a contributing factor for the higher content of biologically active substances. Phenolic content was about twice as low as the flavonoid content, following the same pattern for all tested flavoured salts. Measures for better management of natural populations and promotion of cultivation practices of A. siculum subsp. dioscoridis would ensure the sustainable quality of traditional products as well as conservation of the natural plant resources.  相似文献   
13.
Objective  To document the clinical presentation, diagnostics, treatment, and clinical outcome of rabbits with dacryocystitis.
Materials and methods  This retrospective study included 28 rabbits diagnosed with dacryocystitis. Available records of clinical and ophthalmological examinations, bacteriological samplings, diagnostic imaging, and treatment were reviewed. A telephone survey of the owners was conducted to evaluate recovery and recurrences.
Results  The mean age of the 28 rabbits presenting with ocular discharge from the nasolacrimal duct was 4.4 years. In 25 rabbits (89%), dacryocystitis was a unilateral finding. No underlying cause could be determined in 10 animals (35%). Dental malocclusion was observed in 14 rabbits (50%) and rhinitis in two animals (7%), with one animal showing both symptoms (4%). One rabbit (4%) presented with panophthalmitis. Most animals (96%) received topical antibiotic treatment. If necessary, additional topical (acetylcysteine, vitamin A ointment, nonsteroidals) or systemic treatment (antibiotics, nonsteroidals, paramunity inducer, and glucocorticoids) was provided. The mean duration of therapy was 5.8 weeks. The nasolacrimal duct was flushed in 27 of 31 affected eyes (87%). Dentistry was performed in 80% of the animals suffering from malocclusion. Regarding the clinical outcome, 12 animals (43%) showed complete recovery, eight rabbits (28%) were euthanized, three (11%) died due to unrelated causes, and three (11%) were lost to follow-up. Two rabbits (7%) continue to display signs of dacryocystitis and are being treated symptomatically by the owners.
Conclusions  This study reports the clinical presentation, treatment, and outcome of dacryocystitis in rabbits and outlines the importance of examination of the oral cavity, diagnostic imaging, and bacteriologic sampling.  相似文献   
14.
15.
We used in vitro callus and shoot cultures as target material for genetic transformation of silver birch (Betula pendula Roth) by particle bombardment. Cultivation of in vitro shoot cultures before particle bombardment and a long selection period, combined with a high concentration of selective agent after bombardment, led to the production of transformed plantlets that were stable, and no escapes were found among the tree lines produced. Clonal variation in transformation efficiency was found in transient expression of the beta-glucuronidase gene in callus cultures and in plantlets transformed by stable integration of the ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RbcS) and neomycin phosphotransferase (npt2) genes.  相似文献   
16.
Effects of elevated concentrations of carbon dioxide ([CO2]) and ozone ([O3]) on photosynthesis and related biochemistry of two European silver birch (Betula pendula Roth) clones were studied under field conditions during 1999-2001. Seven-year-old trees of Clones 4 and 80 were exposed for 3 years to the following treatments in an open-top chamber experiment: outside control (OC), chamber control (CC), 2x ambient [CO2] (EC), 2x ambient [O3] (EO) and 2x ambient [CO2] + 2x ambient [O3] (EC+EO). During the experiment, gas exchange, chlorophyll fluorescence, amount and activity of Rubisco, concentrations of chlorophyll, soluble protein, soluble sugars, starch, nitrogen (N) and carbon:nitrogen (C:N) ratio were determined in short- and long-shoot leaves. Elevated [CO2] increased photosynthetic rate by around 30% when measurements were made at the growth [CO2]. When measured at ambient [CO2], photosynthesis was around 15% lower in EC trees than in CC trees. This was related to a approximately 10% decrease in total leaf N, to 26 and 20% decreases in the amount and activity of Rubisco, respectively, and to a 49% increase in starch concentration in elevated [CO2]. Elevated [O3] had no significant effect on gas exchange parameters and its effect on biochemistry was small in both clones. However, elevated [O3] decreased the proportion of Rubisco in total soluble proteins and the apparent quantum yield of photosystem II (PSII) photochemistry in light and increased non-photochemical quenching in 2000. The interactive effect of CO2 and O3 was variable. Elevated [O3] decreased chlorophyll concentration only in EO trees, and the EC+EO treatment decreased the total activity of Rubisco and increased the C:N ratio more than the EO treatment alone. The small effect of elevated [O3] on photosynthesis indicates that these young silver birches were fairly tolerant to annual [O3] exposures that were 2-3 times higher than the AOT40 value of 10 ppm.h. set as a critical dose for forest trees.  相似文献   
17.
The genus Hibiscus thrives in a variety of climates and produces a diversity of natural compounds with bioactive properties. We have studied the chemical composition and the in vivo antioxidant properties of Hibiscus tiliaceus L. methanolic flower extract, as well as its mutagenic/antimutagenic effects. Vitamin E and some stigmasterol derivatives that might confer an antioxidant effect to the extract were present. Treatment with this extract protected several Saccharomyces cerevisiae strains defective in antioxidant defenses against H2O2 and t-BOOH cytotoxicities, showing a clear antioxidant activity. The effect is the same for all strains used, independent of the antioxidant defense disrupted, suggesting that protection may be due to molecules that act as versatile and wide spectrum nonenzymatic antioxidants, such as vitamins or phytosterols. The extract was not mutagenic in either Salmonella typhimurium or S. cerevisiae and showed a significant antimutagenic action against oxidative mutagens in S. cerevisiae.  相似文献   
18.
In the present experiment, the single and combined effects of elevated temperature and ozone (O(3)) on four silver birch genotypes (gt12, gt14, gt15 and gt25) were studied in an open-air field exposure design. Above- and below-ground biomass accumulation, stem growth and soil respiration were measured in 2008. In addition, a (13)C-labelling experiment was conducted with gt15 trees. After the second exposure season, elevated temperature increased silver birch above- and below-ground growth and soil respiration rates. However, some of these variables showed that the temperature effect was modified by tree genotype and prevailing O(3) level. For instance, in gt14 soil respiration was increased in elevated temperature alone (T) and in elevated O(3) and elevated temperature in combination (O(3) + T) treatments, but in other genotypes O(3) either partly (gt12) or totally nullified (gt25) temperature effects on soil respiration, or acted synergistically with temperature (gt15). Before leaf abscission, all genotypes had the largest leaf biomass in T and O(3) + T treatments, whereas at the end of the season temperature effects on leaf biomass depended on the prevailing O(3) level. Temperature increase thus delayed and O(3) accelerated leaf senescence, and in combination treatment O(3) reduced the temperature effect. Photosynthetic : non-photosynthetic tissue ratios (P : nP ratios) showed that elevated temperature increased foliage biomass relative to woody mass, particularly in gt14 and gt12, whereas O(3) and O(3) + T decreased it most clearly in gt25. O(3)-caused stem growth reductions were clearest in the fastest-growing gt14 and gt25, whereas mycorrhizal root growth and sporocarp production increased under O(3) in all genotypes. A labelling experiment showed that temperature increased tree total biomass and hence (13)C fixation in the foliage and roots and also label return was highest under elevated temperature. Ozone seemed to change tree (13)C allocation, as it decreased foliar (13)C excess amount, simultaneously increasing (13)C excess obtained from the soil. The present results suggest that warming has potential to increase silver birch growth and hence carbon (C) accumulation in tree biomass, but the final magnitude of this C sink strength is partly counteracted by temperature-induced increase in soil respiration rates and simultaneous O(3) stress. Silver birch populations' response to climate change will also largely depend on their genotype composition.  相似文献   
19.
Oksanen E 《Tree physiology》2003,23(9):603-614
Physiological responses of 4-year-old potted saplings of an O3-tolerant clone of Betula pendula Roth to short-term ozone (O3) exposure (one growing season) were compared with those of 6-year-old open-soil-grown trees of the same clone fumigated with O3 for six growing seasons. In the 2001 growing season, both groups of plants were exposed to ambient (control) and 1.6x ambient (elevated) O3 concentration under similar microclimatic conditions in a free air O3 exposure facility. Growth, net photosynthesis, stomatal conductance, stomatal density, visible foliar injury, starch and nutrient concentrations, bud formation and differences in O3 responses between lower, middle and upper sections of the canopy were determined. The potted saplings were unaffected by elevated O3 concentration, whereas the open-soil-grown trees showed a 3-38% reduction in shoot growth, a 22% reduction in number of overwintering buds, a 26-65% decrease in autumnal net photosynthesis, 30% and 20-23% reductions in starch and nitrogen concentrations of senescing leaves, respectively, and disturbances in stomatal conductance. The greater O3 sensitivity of open-soil-grown trees compared with potted saplings was a result of senescence-related physiological factors. First, a lower net photosynthesis to stomatal conductance ratio in open-soil-grown trees at the end of the season promoted O3 uptake and decreased photosynthetic gain, leading to the onset of visible foliar injuries. Second, decreased carbohydrate reserves may have resulted in deleterious carry-over effects arising from the reduced formation of over-wintering buds. Finally, the leaf-level O3 load was higher for open-soil-grown trees than for potted saplings because of slower leaf senescence in the trees. Thus, O3 sensitivity in European white birch increases with increasing exposure time and tree size.  相似文献   
20.
Crypthecodinium cohnii is a marine heterotrophic dinoflagellate that can accumulate high amounts of omega-3 polyunsaturated fatty acids (PUFAs), and thus has the potential to replace conventional PUFAs production with eco-friendlier technology. So far, C. cohnii cultivation has been mainly carried out with the use of yeast extract (YE) as a nitrogen source. In the present study, alternative carbon and nitrogen sources were studied: the extraction ethanol (EE), remaining after lipid extraction, as a carbon source, and dinoflagellate extract (DE) from recycled algae biomass C. cohnii as a source of carbon, nitrogen, and vitamins. In mediums with glucose and DE, the highest specific biomass growth rate reached a maximum of 1.012 h−1, while the biomass yield from substrate reached 0.601 g·g−1. EE as the carbon source, in comparison to pure ethanol, showed good results in terms of stimulating the biomass growth rate (an 18.5% increase in specific biomass growth rate was observed). DE supplement to the EE-based mediums promoted both the biomass growth (the specific growth rate reached 0.701 h−1) and yield from the substrate (0.234 g·g−1). The FTIR spectroscopy data showed that mediums supplemented with EE or DE promoted the accumulation of PUFAs/docosahexaenoic acid (DHA), when compared to mediums containing glucose and commercial YE.  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