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   115篇
  免费   11篇
林业   12篇
农学   4篇
基础科学   1篇
  44篇
综合类   10篇
农作物   8篇
水产渔业   10篇
畜牧兽医   13篇
园艺   5篇
植物保护   19篇
  2021年   2篇
  2020年   1篇
  2019年   5篇
  2018年   4篇
  2017年   11篇
  2016年   8篇
  2015年   4篇
  2014年   4篇
  2013年   12篇
  2012年   15篇
  2011年   12篇
  2010年   7篇
  2009年   3篇
  2008年   5篇
  2007年   7篇
  2006年   6篇
  2005年   5篇
  2004年   5篇
  2003年   5篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
排序方式: 共有126条查询结果,搜索用时 93 毫秒
61.
Angiogenesis, including the growth of new capillary blood vessels from existing ones and the malignant tumors cells formed vasculogenic mimicry, is quite important for the tumor metastasis. Anti-angiogenesis is one of the significant therapies in tumor treatment, while the clinical angiogenesis inhibitors usually exhibit endothelial cells dysfunction and drug resistance. Bis(2,3,6-tribromo-4,5-dihydroxybenzyl)ether (BTDE), a marine algae-derived bromophenol compound, has shown various biological activities, however, its anti-angiogenesis function remains unknown. The present study illustrated that BTDE had anti-angiogenesis effect in vitro through inhibiting human umbilical vein endothelial cells migration, invasion, tube formation, and the activity of matrix metalloproteinases 9 (MMP9), and in vivo BTDE also blocked intersegmental vessel formation in zebrafish embryos. Moreover, BTDE inhibited the migration, invasion, and vasculogenic mimicry formation of lung cancer cell A549. All these results indicated that BTDE could be used as a potential candidate in anti-angiogenesis for the treatment of cancer.  相似文献   
62.
Enhanced biodegradation of ethoprophos was evident in a soil from a previously treated field in Northern Greece. However, enhanced biodegradation was specific to ethoprophos and there was no cross‐enhancement leading to rapid degradation for any of the other organophosphorus (cadusafos, fenamiphos, fonofos, isazofos) or carbamate (aldicarb, oxamyl) nematicides registered in Greece for the control of potato cyst nematodes. Studies with radio‐labelled ethoprophos showed that the adapted microflora in the soil from the previously treated field was able to degrade [propyl‐1‐14C]ethoprophos rapidly and mineralized about 60% of the initially applied nematicide. When [ethyl‐1‐14C] ethoprophos was applied, the reduction in extractable radioactivity in the previously treated soil was coupled with evolution of lower amounts of [14C] carbon dioxide and was similar to the amounts produced from the previously untreated soils. It is suggested that degradation of ethoprophos in the soil from the previously treated field proceeds via hydrolysis of the P‐S bond in the ‐S‐propyl moiety of the ethoprophos molecule, which is then further mineralized by the adapted micro‐organisms. Enhanced biodegradation of ethoprophos in this specific previously treated soil in Northern Greece and under the local environmental conditions was still evident two years after the last ethoprophos field application. It appears that, once established, enhanced biodegradation of ethoprophos can be quite stable. A possible solution to this problem might be the introduction of a rotation scheme where other nematicides like fenamiphos, cadusafos, aldicarb or oxamyl are used as alternatives with ethoprophos application restricted to only once every three or four years. © 2000 Society of Chemical Industry  相似文献   
63.
Press juices (PJs) from seven, mostly underutilized, fish were tested for their anti-oxidative properties. The effects of thermal processing, freezing, and lyophilization of fresh PJs on these properties were investigated. Lyophilized samples were further subjected to in vitro digestion. It was concluded that thermal processing significantly affected only the ferric ions reducing ability, while freezing affected the anti-oxidative properties of only certain species. Lyophilized samples from Dactylopterus volitans and Trachinus draco were able to delay significantly the onset of hemoglobin-mediated oxidation. Finally, the exposure of the PJs to different pH values during in vitro digestion seemed to play an important role in their 1,1-diphenyl-2-picrylhydrazyl (DPPH)% inhibition ability.  相似文献   
64.
65.
The biogenic amine (BA) content of vacuum-packed filleted rainbow trout (Oncorhynchus mykiss) inoculated or not with two different Lactobacillus strains, individually or in combination, was monitored during refrigerated storage for 20 days and related to respective bacteriological and sensory changes occurring during the same period. Eight amines, namely putrescine, cadaverine, tyramine, tryptamine, beta-phenylethylamine, histamine, spermine, and spermidine, were determined, whereas agmatine was not detected in any of the samples. In all cases, BA concentration was higher (P < or = 0.05) in the controls compared to all inoculated treatments, whereas the trend with regard to the bacterial populations (Enterobacteriaceae, pseudomonads, and H2S-producing bacteria) and the off-odor scores was similar. Inoculation with Lactobacillus sakei CECT 4808 showed the best preservative effect among inoculated treatments. Concentrations of putrescine and cadaverine, the main BAs formed, correlated well with both spoilage bacterial counts and off-odor scores and can be useful indicators of shelf life. Spermine and spermidine contents decreased during storage, while levels of the other determined BAs remained below 10 mg/kg even after sensory rejection.  相似文献   
66.
Multi-environment trial data are required, to obtain variety stability performance parameters as selection tools for effective cultivar evaluation. The interrelationship among seven stability parameters and their association with mean yield, along with the repeatability of these parameters across consecutive years was the objective of this study. Cottonseed yield data of 31 cotton cultivars, proprietary of Delta and Pine Land Co and other companies, evaluated in 20 locations over the 1999–2005 year period in Greece, Spain and Turkey were used for combined analysis of variance in four datasets. Across locations in a single evaluation year (dataset A), across locations in each of two single consecutive evaluation year (dataset B), across locations and two consecutive years (dataset C) and across locations and three consecutive years (dataset D). For each dataset, cultivar phenotypic variance was appropriately partitioned in its components and the h2 and component estimated. Furthermore, following the appropriate stability analysis and AMMI1 along with the GGE Biplot distance (GGED) and instability (GGEIN) parameters were obtained. The interrelationship among the parameters and their association with mean yield based on Spearman rank correlation was studied in each of the seven single evaluation years (dataset A). Rank correlation coefficients were also used as estimates of the repeatability of these stability parameters across consecutive year combinations (dataset B, C and D). The parameters GGED and YSi were consistently highly correlated with each other and mean yield in five out of seven single evaluation years. The data provided evidence that single year evaluation across locations might be sufficient to reliably rank cotton cultivars, based on mean yield along with GGED and YSi. Combined analysis across two consecutive years (dataset C) was more effective as compared to single year evaluation. GGED was relatively more repeatable than YSi and mean yield in single (dataset B) and 2-year comparisons (dataset C). Although GGED is an index depended and proportional to yield, provides a superior way to integrate mean performance and stability into a single measure, which can be assessed visually on biplots. Regarding the other stability parameters, the results were contradicting and of low repeatability across single years and two consecutive years. Cultivar evaluation combined across locations in 3 years did not improve the repeatability of cultivar variance effects but resulted in very high repeatability of GGED, YSi and mean yield.  相似文献   
67.
Repeated application of diluted olive mill wastewater (OMW) is a common disposal method which allows the application of large amounts of OMW and improves the organic matter and nutrient status of Mediterranean soils. However, there is lack of information regarding the effects of this practice on the soil microbial community. A study was carried out to investigate these effects on the structure of the bacterial and fungal community of a loamy sand (LS) and a sandy loam (SL) soil, using denaturating gradient gel electrophoresis (DGGE) fingerprinting. OMW was daily applied as aqueous solutions of 0, 2 and 4%, in the presence or absence of nitrogen fertilization, for a three-month period. Multivariate analysis of the DGGE profiles showed that OMW applications resulted in marked changes in the fungal community in both soils, while nitrogen fertilization diminished these effects. Small effects were evident for the bacteria only in the LS soil and this was attributed to the higher availability of OMW-derived phenolics in this soil which resulted in a direct impact on bacteria. Nitrogen fertilization alleviated the effects of OMW on the bacterial community. We suggest that the impact of OMW on the structure of the soil microbial communities was mostly a result of its indirect effect on the soil nutritional status, which becomes enriched in organic substrates and poor in available nitrogen.  相似文献   
68.
In the present study, the effects of extracts and polyphenol-rich fractions as well as monomer polyphenols identified in them, from both red and white grapes, on mitomycin C (MMC) induced sister chromatid exchanges (SCEs) in human peripheral blood lymphocytes were investigated. The grape extracts and two of the three polyphenol-rich fractions promoted MMC-induced SCEs at concentrations from 75 to 300 microg/mL. However, none of the extracts or fractions alone induced SCEs. Thus, these results suggest caution especially with regard to the use of grape extracts as dietary supplements. On the other hand, the fact that these extracts were not genotoxic alone may indicate a selective activity against genetically damaged cells. This is the first study regarding the clastogenic effects of grape extracts in human cells. Moreover, from the tested polyphenols, caffeic acid, gallic acid, and rutin hydrate enhanced MMC-induced clastogenicity, whereas ferulic acid, protocatechuic acid, (+)-catechin, (-)-epicatechin, and trans-resveratrol had no effect at concentrations between 5 and 100 microM. The differences in the chemical structures of the tested polyphenols may account for their differential effects on MMC clastogenicity.  相似文献   
69.
The aim of this study was to investigate the efficacy of Sangrovit®, a plant‐derived feed additive, given throughout the nursery stage via feed at 15 ppm and 50 ppm, on the health status and performance of weaners against negative controls. In a 900‐sow farrow‐to‐finish farm, a total of 864 piglets were divided into three groups: (i) negative controls (NC); (ii) Sang 15: same feed as NCs, plus 15 g Sangrovit® /t of feed; (iii) Sang 50: same feed as NCs plus 50 g Sangrovit® /t of feed. The results indicated that administration of 50 ppmSangrovit® had the most beneficial effects on growth performance in weaning pigs. Specifically there was increase of body weight and average daily gain, as well as reduction of feed conversion ratio. Blood analysis from the Sang groups and especially the Sang 50 group revealed low values of haptoglobin and serum amyloid A.  相似文献   
70.
Water management for irrigation in areas with high water scarcity includes not only domestic wastewater treatment but also practices for the reuse of drainage water during the irrigation period. The main problem that concerns the reuse of drainage water for irrigation is the accumulation of salts due to the effluents existing in the soil. In this paper an optimization technique is proposed for the management of drainage water that uses, in combination, a soil-water-plant model (SWAP) and a mixed 0-1 linear programming method. The optimization routine was applied to the irrigation network of Alfeios River in Western Greece, an area that is characterized by high precipitation imbalances between winter and summer months.  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