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   36篇
  免费   1篇
林业   4篇
农学   1篇
  9篇
农作物   1篇
水产渔业   2篇
畜牧兽医   17篇
园艺   1篇
植物保护   2篇
  2019年   3篇
  2018年   2篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2013年   7篇
  2012年   3篇
  2011年   4篇
  2010年   2篇
  2009年   1篇
  2008年   3篇
  2007年   1篇
  2006年   2篇
  2005年   1篇
  2004年   2篇
  1999年   1篇
排序方式: 共有37条查询结果,搜索用时 15 毫秒
11.
Background – In humans, thymic stromal lymphopoietin (TSLP) plays a central role in the development of allergic inflammation, such as atopic dermatitis (AD), but it is unknown whether it is involved in the pathogenesis of canine AD (CAD). Hypothesis/Objectives – Our aim was to characterize canine TSLP and to assess its expression in CAD. Methods – Canine TSLP was identified based on sequence homology with human TSLP and the complementary DNA (cDNA) cloned by RT‐PCR. Real‐time quantitative RT‐PCR was established to assess the expression of canine TSLP in cultured canine keratinocytes and in skin biopsy specimens from lesional and nonlesional skin of 12 dogs with CAD and eight healthy control dogs. Results – Partial canine TSLP cDNA was cloned and characterized. It contained four exons that shared 70 and 73% nucleotide identity with human and equine TSLP, respectively, encoding the signal peptide and full‐length secreted protein. We found significantly increased TSLP expression in lesional and nonlesional skin of dogs with CAD compared with healthy control dogs (P < 0.05), whereas no difference was measured between lesional and nonlesional samples. In cultured primary canine keratinocytes, we found increased TSLP expression after stimulation with house dust mite allergen extract or Toll‐like receptor ligands lipopolysaccharide and poly I:C. Conclusions and clinical importance – Increased TSLP expression in the skin of dogs with CAD supports an involvement of TSLP in the pathogenesis of CAD similar to that in humans. Further studies should elucidate the function and therapeutic potential of TSLP in CAD.  相似文献   
12.
Background, aim, and scope  Ionic liquids (ILs) are a new class of alternative solvents that make ideal non-volatile media for a variety of industrial processes such as organic synthesis and biocatalysis, as alternative electrolytes, as phases and phase modifications in separation techniques, and as alternative lubricants. Once the large-scale implementation of ILs begins, the industrial application will follow. In view of their great stability, they could slip through classical treatment systems to become persistent components of the environment, where the long-term consequences of their presence are still unknown. Sorption on soils has a critical effect on the transport, reactivity, and bioavailability of organic compounds in the environment. So far, the IL sorption mechanism was investigated solely on the basis of batch experiments, which precluded any assessment of the dynamics of the process. An understanding of the mobility of ILs in soil columns is crucial for an accurate prediction of their fate in the soil. The aim of this study therefore was to investigate in detail the mobility of selected imidazolium ILs on three soil types. Moreover, it was decided to study these processes in soils from the coastal region (Gdańsk, Poland), which usually constitute a very important geochemical compartment, participating in the transport of contaminants on their way to the sea. Materials and methods  The mobility of alkylimidazolium ILs was investigated in columns containing soils from the coastal area. In addition, the sorption processes in all the soil systems studied were described isothermally and the equilibrium sorption coefficient was evaluated. The sorption capacities were determined according to OECD guidelines. Sorption dynamics was studied with use of polypropylene columns (diameter—10 mm, height—100 mm) packed with 10 g of soil. The ionic liquid solution was then injected into the soil column and left for 24 h to equilibrate. After this, a solution of 0.01 mM CaCl2 was pumped through the column at a rate of 0.3 ml min–1. Effluents were collected from the bottom of the column and analyzed by HPLC. Results  Sorption was strongest on the Miocene silt and the alluvial agricultural soil and weakest on the podsolic soil and Warthanian glacial till. The K d value of long-chain ILs was far higher than that of the short-chain ones. Among the substances tested, hydroxylated ILs were usually more weakly sorbed. Desorption of ILs is inversely correlated with sorption intensity. The experimental results of the column tests correlate well with those from batch experiments. In the cases of weakly binding soils, ILs were detected almost immediately in the eluent. The elution profiles of long-chain ILs indicate that these compounds are very strongly sorbed onto most soils, although certain amounts were transported through the soil. ILs exhibit a certain mobility in soils: in particular, salts with short and/or hydroxylated side chains are extremely mobile. Discussion  The results indicate a stronger binding of ILs in the first sorption layer; once the first layer is saturated, there are no more active sites on the soil surface (no free charged groups); hence, there are no more strong electrostatic binding sites, and dispersive interaction becomes the dominant interaction potential. The influence of the structure of the ILs, especially the side-chain length was also confirmed: The K d value of long-chain ILs was far higher than that of the short-chain ones. The long alkyl side chain facilitates dispersive interactions with soil organic matter and intermolecular binding, and the build-up of a second layer becomes possible. Among the substances tested, hydroxylated ILs were usually more weakly sorbed. The hydroxyl group in the side chain can alter the polarity of the compound so strongly that interaction with organic matter hardly occurs; these salts then remain in the aqueous phase. The experimental results from the column tests correlate well with those from batch tests. In the weakly binding soils (with low organic matter), the only binding to the soil surface must be via electrostatic interactions, although intermolecular van der Waals (ionic liquid–ionic liquid) interactions could also be taking place. The elution profile maxima for organic rich soils are far smaller than for the other soils. In the former, hydrogen bonding, dispersive and π…π interactions play a more important part than electrostatic interactions. The rapidly “disappearing” maxima of the elution peaks may indicate that, after elution of ILs from the second layer, it is difficult to extract further sorbed ILs. In the first layer, the ILs are bound by much stronger electrostatic interactions. To break these bonds, a greater energy is required than that sufficient to extract ILs from double sorption layers. Results indicate, moreover, that hydrophobic ILs will be sorbed in the first few centimeters of the soil; migration into the soil will therefore be almost negligible. Conclusions  Sorption of ILs was the strongest in soils with the highest cation exchange capacities and a high organic content. ILs were also more strongly bound to the first sorption layer. The sorption coefficients of long-chain ILs were far higher than those of short-chain ones; usually, hydroxylated derivatives were the least strongly sorbed. Results of soil column experiments to investigate the mobility of ILs in soils correlated well with those from batch tests, and the elution profiles were also well correlated with organic matter content. The observed rapidly disappearing elution peak maxima probably indicate that, after elution of the ILs from the second layer, it is difficult to extract further sorbed compounds. Recommendations and perspectives  Obtained results gave an interesting insight into mobility of ionic liquids in soil columns. However, several questions are now opened. It is therefore necessary to undertake further studies focused on total cycle of ionic liquids in the soil environment. This should include their evapotrasporation (lysimeter test), bioaccumulation by plants as well as degradation and transformation processes (chemical, biological, and physical) typically occurring in soils. Moreover, a further risk assessment of ILs is desirable since this study has indicated that these compounds, especially those with low lipophilicities, are generally mobile in the soil matrix. It is already known that short-chain ILs are characterized by low toxicities; should they enter the environment, they will probably migrate within the soil and pose a risk of contamination of surface and ground waters. This topic is relevant to the audience. Environmental threat of short-chain ionic liquids is currently unknown. From the predictive point of view, judging on known low acute toxic effects or high polarities of these compounds seems to be not enough to confirm their “environmental friendliness”. If we are to fully understand the potential environmental effects, one should also have an insight into long-term biological consequences of these ionic liquids, including chronic toxicity tests, bioaccumulation, and biotransformation rates as well as stability against natural elimination mechanisms.  相似文献   
13.
Chlorinated macrolides, haterumalide NA, B and NE, and a new haterumalide X, were produced by the soil bacterium Serratia plymuthica. Haterumalides NA, B and NE caused complete suppression of apothecial formation in sclerotia of Sclerotinia sclerotiorum at a concentration of 0.5 μg ml−1. Ascospore germination of this fungus was inhibited in the concentration range 0.8-3.0 μg ml−1. Haterumalides NA, B and NE prevented spore germination of several other filamentous fungi as well as Oomycetes at concentrations ranging from 0.4 to 40 μg ml−1, but did not show any effect against the yeast Candida albicans. Inhibition data could not be collected for haterumalide X due to its rapid conversion to haterumalide NA. The bacterium also produced two other antifungal metabolites: pyrrolnitrin and 1-acetyl-7-chloro-1-H-indole, which in contrast to the haterumalides, did not inhibit the apothecial formation on sclerotia. Pyrrolnitrin, and haterumalide NA, B and NE effectively inhibited spore germination of tested filamentous fungi at concentrations ranging from 0.06 to 50 μg ml−1, whereas 1-acetyl-7-chloro-1-H-indole inhibited spore germination only at concentrations above 50 μg ml−1. The minimal inhibitory concentrations of the respective compounds needed for total inhibition of spore germination varied for the fungal species tested.  相似文献   
14.
15.
A widespread, severe outbreak of canine distemper encephalitis was observed in wildlife in Southern Bavaria in the spring and summer of 2008. The haemagglutinin (HA) genes of six representative canine distemper virus (CDV) samples originating from five red foxes and one badger during this outbreak had a Y549H amino acid substitution in the HA protein compared to sequences from two captive domesticated ferrets which succumbed to CDV in the same area 2 years earlier. As this specific substitution at the receptor-binding site has been hypothesised to contribute to the emergence of CDV and its spread to novel hosts, the outbreak in wildlife in Southern Bavaria might, directly or indirectly, be associated with a Y549H amino acid exchange.  相似文献   
16.
Each living cell of a plant produces photons in certain conditions. Under normal physiological conditions, cell photon emission is stationary and minimal. Disturbance in the oxidative homeostasis by biotic stress is manifested by increased ‘biophoton’ production. Such biophoton responses of plants may be used as an integral indicator of the degree of oxidative homeostasis misbalance. Our results demonstrate that biophoton generation has been much higher in a resistant potato variety than in a susceptible one till 10 h after Phytophthora infestans inoculation. In contrast, ultra-weak luminescence from detached susceptible potato and moderately resistant pelargonium leaves increased from 1–4 to 4–5 days after inoculation with Phytophthora infestans or Botrytis cinerea, respectively. Pre-treatment of susceptible potato leaves with a defence inducer, arachidonic acid, resulted in a transient burst of light in response to P. infestans lasting for 30–45 h post inoculation (hpi). This study presents the potential adaptation of functional imaging of ultra-weak luminescence to monitor time-dependent free radical processes during disease development and its application to draw conclusions on plant resistance to pathogens of different lifestyle. Moreover, it has been shown that imaging of temporal biophoton generation from potato leaves treated with arachidonic acid might be a helpful marker in mapping oxidative changes leading to systemic acquired resistance (SAR).  相似文献   
17.
Abstract

A field experiment was conducted during the period 2002–2006 at the Experimental Farm in Zawady, located in the mid-eastern part of Poland, to evaluate the effect of date of mulch ploughing down (autumn, spring, left till cabbage harvest) and the plant mulches [phacelia (Phacelia tanacetifolia Benth.), vetch (Vicia sativa L.), serradella (Ornithopus sativus), and oat (Avena sativa L.)] on the weed pressure in red cabbage (Brassica oleracea L. var. capitata L. f. rubra) in the first and onion (Allium cepa L. var. cepa Helm.) in the second year after mulching. The biomass yield of plant mulches, total cabbage and onion yields, and biomass and number of weeds before planting and harvest of cabbage and before sowing and harvest of onion were assessed. Weed infestation was determined by the quantitative-weighting method. The biomass yields of phacelia and oat amounted to 26.6 and 24.8 t·ha?1, respectively, and were almost 2.5-times higher than biomass yields of serradella and vetch. The average cabbage and onion yields were 45.8 and 41.9 t·ha?1, respectively. The yields of vegetables following mulches were higher than the yields recorded in the unmulched control. The weed species most often found in the experiment were Viola arvensis Murr., Capsella bursa pastoris, Matricaria indora L., Chenopodium album L., and Stellaria media (L.) Vill. Of the examined dates of mulch ploughing down, the spring-incorporated mulches were most effective in reducing the number of weeds in cabbage whereas the nonincorporated mulches showed such an effect in onion. Nonlegumes (phacelia and oat) used as mulch produced higher fresh biomass yields than did vetch and serradella. Oat and phacelia mulches significantly reduced the fresh biomass and number of weeds before cabbage planting. Additionally, oat mulch reduced the fresh biomass of weeds before cabbage harvest. Also, oat and phacelia mulches reduced the number of weeds before onion harvest.  相似文献   
18.
ABSTRACT

The research analyses the influence of the number of washings and different washing solutions, on the recovery of dry matter and protein in a preparation made from freshwater mussel Sinanodonta woodiana, (Lea, 1834). The study involved qualitative and quantitative characterisation of mussel protein preparation (MPP) obtained by electrophoretic separation and differential scanning calorimetry (DSC). The type of washing agent had the greatest influence on dry matter and protein content. Washing the homogenate with NaCl solutions and water was more effective on protein extraction than using only water. Two bands of proteins with molecular weights of 270–273 kDa and 42–43 kDa were characterized by the highest band intensity in electropherograms. The DSC analysis showed that on all denaturation curves of the samples there was one main peak of transformation ranging 56.69–62.94°C. The research revealed that washing homogenates with NaCl solutions caused the appearance of additional peaks at lower transformation temperatures, i.e. from 19.68°C to 36.45°C. The highest enthalpy value (4.53 Jg?1) was observed for the sample washed once NaCl solution and then water. The number of washings (1 or 2) and the use of a 0.5% NaCl solution or water were found to be the most favorable parameters for MPP production.  相似文献   
19.
Fusarium head blight (FHB), caused by the fungal plant pathogen Fusarium, is a fungal disease that occurs in wheat and can cause significant yield and grain quality losses. The present paper examines variation in the resistance of spring wheat lines derived from a cross between Zebra and Saar cultivars. Experiments covering 198 lines and parental cultivars were conducted in three years, in which inoculation with Fusarium culmorum was applied. Resistance levels were estimated by scoring disease symptoms on kernels. In spite of a similar reaction of parents to F. culmorum infection, significant differentiation between lines was found in all the analyzed traits. Seven molecular markers selected as linked to FHB resistance QTLs gave polymorphic products for Zebra and Saar: Xgwm566, Xgwm46, Xgwm389, Xgwm533, Xgwm156, Xwmc238, and Xgwm341. Markers Xgwm389 and Xgwm533 were associated with the rate of Fusarium-damaged kernels (FDK) as well as with kernel weight per spike and thousand kernel weight in control plants. Zebra allele of marker Xwmc238 increased kernel weight per spike and thousand kernel weight both in control and infected plants, whereas Zebra allele of marker Xgwm566 reduced the percentage of FDK and simultaneously reduced the thousand kernel weight in control and infected plants.  相似文献   
20.
Crop performance and yield are the results of genotypic expression as modulated by continuous interaction with the environment. Among environmental factors, water is globally one of the most limiting for crop production. Water resources in the world are steadily diminishing and in many areas, including Poland, more frequent periods of drought are being observed. The aim of the study was to compare the yields and gas exchange parameters of Festulolium hybrid (Festulolium braunii (K. Richt) A. Camus) and alfalfa (Medicago?×?varia T. Martyn) under different levels of soil moisture (well-watered conditions and drought stress) and cultivation method (pure stand and mixture). The study has shown that all the measured parameters were affected by drought stress. Net photosynthetic rate, transpiration rate, stomatal conductance and dry mass yield were significantly lower under drought stress than under well-watered conditions in all treatment types. Alfalfa grown in a pure sowing showed the strongest reaction to stress, while hybrid Festulolium grown in mixture showed the weakest. It was also found that under stress, grass assimilated CO2 and evaporated water much more intensively in mixture cultivation than in pure sowing. Higher water use efficiency (WUE) was observed in alfalfa and Festulolium growing in mixture only in the first year of the study.  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