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   55篇
  免费   2篇
林业   1篇
农学   5篇
  29篇
综合类   2篇
农作物   5篇
畜牧兽医   8篇
园艺   1篇
植物保护   6篇
  2020年   1篇
  2019年   2篇
  2018年   3篇
  2017年   3篇
  2016年   4篇
  2015年   2篇
  2014年   1篇
  2013年   2篇
  2012年   4篇
  2011年   4篇
  2010年   1篇
  2009年   1篇
  2008年   10篇
  2007年   4篇
  2006年   3篇
  2005年   1篇
  2003年   2篇
  2002年   1篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1993年   1篇
排序方式: 共有57条查询结果,搜索用时 364 毫秒
31.

Investigations were carried out to assess air and potable waterpollution with selected highly bioactive organic compounds,including polycyclic aromatic hydrocarbons (PAHs), in theenvironment of the Silesian Rehabilitation Centre, Repty ?l?skie, Poland. The results were compared with those forother towns of the region.Solid phase extraction (SPE) and capillary gas chromatography(CGC) with flame ionization detector (FID) and mass spectrometer(MS) were used for a qualitative-quantitative analysis. Moreover, water concentration of calcium, magnesium ions andnitrite ions were measured by spectrophotometric methods. Thequality of the Centre environment air and water found to besatisfactory and better than that in the other sampling sites which were studied for all the parameters.

  相似文献   
32.
This paper reports the use of spectrophotometric and voltammetric methods for the determination of the antioxidant capacity of buckwheat and its products originated from a technological line of a buckwheat roasted groats producer. 80% methanol extracts from raw and roasted buckwheat and groats and hulls obtained from roasted buckwheat were used. The spectrophotometric methods included (1) free radical scavenging activities of the extracts against ABTS*+ radical cation (TEAC) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH RSA) and (2) determination of reducing capacity by the means of Folin-Ciocalteu reagent (FCR) application. The radical scavenging activities of the extracts were also investigated using a voltammetric assay. Moreover, the flavonoids profiles of the studied materials were provided. Buckwheat roasting caused a decrease in TEAC, DPPH RSA, and FCR reducing capacity by 70%. The lowest TEAC, DPPH RSA, and FCR reducing capacities were noted for roasted groats. Both DPPH RSA and TEAC methods were highly positively correlated with the FCR reducing capacity assay (r = 0.98 and r = 0.99). Cyclic voltammograms of analyzed buckwheat extracts were useful for evaluation of the antioxidant capacity. The total charge below the anodic current waveform was correlated with the data obtained by TEAC (r = 0.770), DPPH RSA (r = 0.88), and FCR reducing capacity (r = 0.81). The changes in the antioxidant capacity of buckwheat and its products followed the changes in flavonoids composition. In particular, the concentration of flavonoids was related to measurements by cyclic voltammetry.  相似文献   
33.
How chaperone interactions affect protein folding pathways is a central problem in biology. With the use of optical tweezers and all-atom molecular dynamics simulations, we studied the effect of chaperone SecB on the folding and unfolding pathways of maltose binding protein (MBP) at the single-molecule level. In the absence of SecB, we find that the MBP polypeptide first collapses into a molten globulelike compacted state and then folds into a stable core structure onto which several alpha helices are finally wrapped. Interactions with SecB completely prevent stable tertiary contacts in the core structure but have no detectable effect on the folding of the external alpha helices. It appears that SecB only binds to the extended or molten globulelike structure and retains MBP in this latter state. Thus during MBP translocation, no energy is required to disrupt stable tertiary interactions.  相似文献   
34.
The Ny-1 and Ry-fsto genes of potato (Solanum tuberosum L.) confer hypersensitive response (HR) and extreme resistance (ER), respectively, to Potato virus Y (PVY). ER-type resistance was also observed in potato plants with both alleles (Ny-1 and Ry-fsto). Using two-dimensional electrophoresis (2-DE), quantitative differences between PVY-infected and non-infected control plants were found for 35, 32 and 15 protein spots identified in leaves of potato cultivar Rywal (possessing Ny-1), and potato tetraploid clones PW 363 (with Ry-fsto) and PB 08–137 (with Ny-1 + Ry-fsto), respectively. We recognized 29, 12 and 21 PVY-induced protein spots involved in qualitative changes in Rywal, PW 363 and PB 08–137 plants, respectively, which were processed and analysed using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. A database search indicated that these 62 proteins belong to various functional categories. Their expression was genotype-specific. In the case of cultivar Rywal with HR-mediated resistance, proteins involved in photosynthesis and primary metabolism were the most abundant. For PW 363 and PB 08–137, both with ER–mediated resistance, stress-responsive proteins were the most numerous. Only two proteins – glutamate–glyoxylate aminotransferase 2 (GGAT2) and monodehydroascorbate reductase 5 (MDHAR5) – were identified in all three genotypes. These two proteins are components of the reactive oxygen species (ROS) defence mechanism against pathogens in plants. The present study showed that the differences in PVY-induced proteins in the leaves of Ny-1, Ry-fsto and Ny-1 + R-fsto genotypes do not correspond to the type of gene conferring the resistance or to the observed phenotype.  相似文献   
35.
One hundred and fifty bread wheat lines and 50 other lines of small-grain cereals (spelt, durum wheat, Triticum monococcum, Triticum dicoccum, oats, rye, and barley) were selected for diversity in their geographical origin, age, and characteristics. They were grown on a single site in Hungary in 2004-2005, harvested, milled, and analyzed for a range of phytochemicals (tocols, sterols, phenolic acids, folates, alkylresorcinols) and fiber components that are considered to have health benefits. Detailed analyses of these components in the different species are reported in a series of accompanying papers. The present paper discusses the comparative levels of the bioactive components in the different species, showing differences in both ranges and mean amounts. Furthermore, detailed comparisons of the bread wheat lines show that it is possible to identify lines in which high levels of phytochemicals and dietary fiber components are combined with good yield and processing quality. This means that commercially competitive lines with high levels of bioactive components are a realistic goal for plant breeders.  相似文献   
36.
Silicon (Si) is the second‐most abundant element in the earth's crust. In the pedosphere, however, huge spans of Si contents occur mainly caused by Si redistribution in soil profiles and landscapes. Here, we summarize the current knowledge on the different pools and fluxes of Si in soils and terrestrial biogeosystems. Weathering and subsequent release of soluble Si may lead to (1) secondarily bound Si in newly formed Al silicates, (2) amorphous silica precipitation on surfaces of other minerals, (3) plant uptake, formation of phytogenic Si, and subsequent retranslocation to soils, (4) translocation within soil profiles and formation of new horizons, or (5) translocation out of soils (desilication). The research carried out hitherto focused on the participation of Si in weathering processes, especially in clay neoformation, buffering mechanisms for acids in soils or chemical denudation of landscapes. There are, however, only few investigations on the characteristics and controls of the low‐crystalline, almost pure silica compounds formed during pedogenesis. Further, there is strong demand to improve the knowledge of (micro)biological and rhizosphere processes contributing to Si mobilization, plant uptake, and formation of phytogenic Si in plants, and release due to microbial decomposition. The contribution of the biogenic Si sources to Si redistribution within soil profiles and desilication remains unknown concerning the pools, rates, processes, and driving forces. Comprehensive studies considering soil hydrological, chemical, and biological processes as well as their interactions at the scale of pedons and landscapes are necessary to make up and model the Si balance and to couple terrestrial processes with Si cycle of limnic, fluvial, or marine biogeosystems.  相似文献   
37.
Fluazifop-p-butyl (FL) is one of the most popular graminicides from arylophenoxypropionate group. These herbicides act as inhibitors of acetyl-CoA carboxylase (ACCase) that catalyzes the formation of malonyl-CoA during metabolism of lipids and/or of some secondary compounds. On the other hand arylopropionates and cyclohexanediones cause phytotoxic effects by stimulating free-radicals generation and causing oxidative stress in susceptible plants. However, the importance of disturbances in plant pigments and polyamines accumulation for this effect is not clear. The aim of this work is to quantify the phytotoxicity of FL to non target maize plant and to explain how photosynthetic pigments, anthocyanins (ANC) and polyamines participate in this interaction.  相似文献   
38.
Unprocessed pomace containing 61% of dietary fiber (DF) and 0.23% of polyphenols (PP) and ethanol- or ethanol/acetone-extracted pomaces containing 66% DF and 0.10% PP and 67% DF and 0.01% PP, respectively, were subjected to a 4 week study in rats. The aim of the study was assessing the advantages of dietary supplementation with the above pomaces. To measure the animal response to dietary treatments, parameters describing cecal fermentation and lipoprotein profile were assessed. The dietary use of 5% unprocessed pomace caused an increase in cecal short-chain fatty acid (SCFA) production and a decrease in blood triacylglycerols, leading to a drop in serum atherogenic index. Ethanol-extracted pomace increased the glycolytic activity of cecal microbiota and decreased cecal branched-chain fatty acid production, whereas acetone extraction led to lower cecal ammonia concentration, decreased colonic pH value, and higher HDL/total cholesterol ratio. The variations in the atherogenic index indicate flavonoids as the key pomace component in relation to blood lipid profile benefits.  相似文献   
39.
Summary Content of dietary fibre (DF) as well as content and composition of non-starch polysaccharides (NSP) were evaluated in disomic wheat-rye addition lines and octoploid triticale compared to their parental species — wheat (Grana) and rye (Dakowskie Zote). Large variation in the contents of NSP and DF were observed in the wheat-rye addition lines, especially in the soluble fractions. The double addition of rye chromosomes led to important transgression effects on content and composition of DF in wheat grain. Chromosomes 2R and 5R increased SDF content above the rye level, whereas the 3RS arm decreased SDF content below the wheat level. The octoploid triticale demonstrated the highest content of total arabinoxylan (AX), exceeding that of rye, while the double addition of chromosomes 4R, 6R and 6RL had an impact on high expression, comparable to that of rye content of total AX in wheat grain. Chromosomes 2R and 5R notably increased the proportion of soluble non-cellulosic glucose in the NSP fraction, in contrast to the rest of wheat-rye addition lines, octoploid triticale, wheat and rye, where AX was found to be predominant among NSP constituents. The effects of single chromosome pairs on content and composition of NSP proved to be higher than the effect of the whole rye genome in octoploid triticale. The most remarkable effect, especially considering the direction of changes, was of a 3R chromosome short arm addition. The obtained data might be of interest in breeding rye or triticale with lower viscous AX content as well as rich in soluble non-starch glucose polymers, regarded as a corrective factor in modern diseases.Abbreviations AX arabinoxylan - CV coefficient of variation - DF dietary fibre - IDF insoluble dietary fibre - NSP non-starch polysaccharides - SDF soluble dietary fibre - TDF total dietary fibre - TFA trifluoroacetic acid  相似文献   
40.
In recent years, there has been an ever-increasing interest in the research of polyphenols obtained from dietary sources, and their antioxidative properties. The purpose of this study was to determine the effect of boiling buckwheat and barley groats on the antioxidant properties and dietary fiber composition. Antioxidative properties were investigated using methyl linoleate model system, by assessing the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and metal chelating activity. The results were compared with butylated hydroxytoluene (BHT). Raw barley and buckwheat groats extracts showed higher DPPH scavenging ability compared to boiled barley and buckwheat groats extracts. Raw barley groats extract exhibited higher antioxidant activity than boiled groats extract in the methyl linoleate emulsion. Higher chelating ability in relation to Fe (II) ions was observed for boiled groats extracts as compared to raw groats extracts. BHT showed small antiradical activity and metal chelating activity, while showing higher antioxidative activity in emulsion system. The analysis of groats extracts using HPLC method showed the presence of rutin, catechin, quercetin, gallic, p-hydroxybenzoic, p-coumaric, o-coumaric, vanillic, sinapic, and ferulic acids. Differences in the content of dietary fiber and its fractions were observed in the examined products. The highest total dietary fiber content was detected in boiled buckwheat groats, while the lowest - in boiled barley groats. The scientific achievements of this research could help consumers to choose those cereal products available on the market, such as barley and buckwheat groats, which are a rich source of antioxidative compounds and dietary fiber.  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