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   71篇
  免费   2篇
林业   5篇
农学   1篇
  7篇
综合类   7篇
农作物   6篇
水产渔业   2篇
畜牧兽医   44篇
植物保护   1篇
  2021年   3篇
  2020年   7篇
  2019年   3篇
  2018年   3篇
  2017年   3篇
  2015年   2篇
  2014年   3篇
  2013年   7篇
  2012年   7篇
  2011年   6篇
  2010年   3篇
  2008年   2篇
  2007年   4篇
  2006年   2篇
  2005年   4篇
  2004年   6篇
  2003年   3篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
排序方式: 共有73条查询结果,搜索用时 281 毫秒
41.
Mechanisms related to the induction of phlorotannin biosynthesis in marine brown algae remain poorly known. Several studies undertaken on fucoid species have shown that phlorotannins accumulate in the algae for several days or weeks after being exposed to grazing, and this is measured by direct quantification of soluble phenolic compounds. In order to investigate earlier inducible responses involved in phlorotannin metabolism, Fucus vesiculosus was studied between 6 and 72 h of grazing by the sea snail Littorina littorea. In this study, the quantification of soluble phenolic compounds was complemented by a Quantitative real-time PCR (qRT-PCR) approach applied on genes that are potentially involved in either the phlorotannin metabolism or stress responses. Soluble phlorotannin levels remained stable during the kinetics and increased significantly only after 12 h in the presence of grazers, compared to the control, before decreasing to the initial steady state for the rest of the kinetics. Under grazing conditions, the expression of vbpo, cyp450 and ast6 genes was upregulated, respectively, at 6 h, 12 h and 24 h, and cyp450 gene was downregulated after 72 h. Interestingly, the pksIII gene involved in the synthesis of phloroglucinol was overexpressed under grazing conditions after 24 h and 72 h. This study supports the hypothesis that phlorotannins are able to provide an inducible chemical defense under grazing activity, which is regulated at different stages of the stress response.  相似文献   
42.
43.
The thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is among the most important pests of greenhouse crops in Europe and causes considerable damage to commercial rose crops. The usage of pesticides is associated with major problems, and thus the interest of implementing integrated pest management (IPM) for rose crops is increasing. One essential component of IPM is field monitoring/scouting. Growers use information gathered from scouting to select and schedule appropriate control tactics. Thrips populations were surveyed in 2005 and 2006 in a greenhouse planted with roses, Rosa x Hybrida in Southern of France. From April to August, thrips were counted using yellow sticky traps (YST), knock-down techniques [i.e., tapping flower heads (FT)] and actual counts of entire plants. Thrips abundance recorded using YST correlated well with abundance levels determined through FT or actual counts (whole plant). Our results demonstrate that it is accurate to estimate thrips populations using YST in rose crops in greenhouse. Because YST takes at least twice less time than other monitoring methods, it could be used as a valid and easy monitoring technique in further development of IPM programs on roses. The possibility of setting a damage threshold using the data from the YST in the greenhouse is discussed.  相似文献   
44.
In first part of this study, influences of wash-ageing and the use of fabric softener on the different mechanical parameters of textiles were examined. This paper deals with correlation of those mechanical parameters with sensory attributes. We defined the tracking criterion to investigate the relevancy of mechanical parameters with different sensory attributes. An intelligent system based on Fuzzy-Logic was developed in order to predict the sensory attribute score using two most relevant mechanical parameters.  相似文献   
45.
46.
A barley core collection can be studied extensively and the derived information can be used to identify loci/genes for the genetic improvement of quantitative and qualitative traits. To assess genetic diversity, allelic variation and population structure of Egyptian barley, 134 barley genotypes collected from a different region along with 19 cultivated genotypes obtained from of the Egyptian Agricultural Research Center. All genotypes were analyzed with 261 polymorphic SSR and SNP alleles. The mean number of alleles per locus was 4 and PIC was 0.49, while the level of genetic diversity was 0.55 ranging from 0.03 to 0.82. The genotypes were assigned to three subpopulations that were consistent with their origins. The genetic variation within population was higher (51%) than among population at the molecular levels (FST =?0.491 when P?<?0.10). The level of polymorphic variation was highest in subpopulations-II, due to collected from different regions with different ear-types thus, expected to contain more diversity than local genotypes in subpopulations-I and subpopulations-III. The structured study found that the 153 barley genotypes are in harmony with clustering approaches using the SSR and SNP genotypic data in a neighbor-joining tree and principal components analysis, which identified three subpopulations. These results demonstrated genetic diversity among the Egyptian barley genotypes can be applied to suggest approaches, such as association analysis, classical mapping population development, and parental line selection in breeding programs. Therefore, it is necessary to use the exotic genotypes as the genetic resources for developing new barley cultivars in Egypt.  相似文献   
47.
Castanea sativa forests in north‐eastern Spain have historically been healthy and have been good producers of timber and non‐wood forest products. In the last quarter of a century, Fistulina hepatica has gained relevance in this ecosystem and is believed to be responsible for Chestnut Red Stain (CRS), which inflicts heart rot in trees and causes severe economic losses. The fungus grows in the heartwood and produces no external symptoms that would enable early detection. With the objective of developing an inexpensive method to detect heart rot and to discover possible relationships between the severity of F. hepatica attack and the silvicultural management or site characteristics of chestnut stands, 38 pure C. sativa plots were selected, sampled and analysed for the presence of the fungus. DNA was extracted from the heartwood samples, and PCR was used to amplify target sequences with specific F. hepatica primers for non‐homologous ITS1 and ITS2 regions. Correlation analysis was used to inspect the multiple interactions among the environmental and management variables examined, and a predictive model was designed for forest managers to estimate the risk of infection. Both analyses revealed that stress variables were related to CRS severity. This result is especially relevant since temperatures are expected to rise in coming decades throughout the northern rim of the Mediterranean region, where chestnut is an important species. This study provides two tools for better managing chestnut forests in the coming years: an inexpensive and fast tool for diagnosis and a predictive model to estimate the risk of infection.  相似文献   
48.
OBJECTIVE: To assess the efficacy of laparoscopic adhesiolysis in the treatment of experimentally induced adhesions in foals. ANIMALS: 8 healthy pony foals. PROCEDURE: Celiotomy was performed and adhesions created at the jejunoileal junction and at sites 0.5 and 1 m proximal to this junction, using a serosal abrasion method. Ten days after celiotomy, exploratory laparoscopy was performed. Laparoscopic adhesiolysis was performed in the treatment group only (4 foals, randomly selected). Thirty days after the exploratory laparoscopy, a final laparoscopic examination was performed, and the foals were euthanatized. The number and characteristics of abdominal adhesions were recorded during laparoscopy 10 and 30 days after celiotomy and during necropsy. RESULTS: At 30 days after celiotomy, the number of adhesions in the control group was significantly higher than the number in the treatment group. In the control group, all adhesions observed during the exploratory laparoscopy were still evident at the final laparoscopy and necropsy. In the treatment group, adhesions did not form again after separation. During final laparoscopy and necropsy, a focal adhesion between the omentum and site of the initial laparoscope portal was observed in 5 of 8 foals. CONCLUSIONS AND CLINICAL RELEVANCE: The serosal abrasion model is useful for studying abdominal adhesions in foals. Laparoscopic adhesiolysis was an effective technique to break down experimentally induced adhesions in the early maturation stage of formation in pony foals. Studies are required to investigate prevention of de novo adhesions at the laparoscope portal sites.  相似文献   
49.
  • ? We examined the relationships between productivity, leaf traits and carbon isotope discrimination in bulk leaf matter (Δ1) and in phloem sap (Δs) from more than 5-year-old trees belonging to Populus deltoides × P. nigra and Populus trichocarpa × P. deltoides; trees were grown in alluvial and non alluvial sites in a commercial poplar plantation.
  • ? On both sites, a large genetic variability was evidenced for all variables. The genotypic ranking remained stable between years for all variables, while it differed between sites. Δ1 scaled positively with Δs and neither Δ1 nor Δs were correlated with productivity. A significant genotype by site interaction was evident for all variables. The non alluvial site resulted in lower productivity, and in thicker/denser leaves with lower nitrogen and carbon contents. Noteworthy, the genotypic ranking for Δ1 measured at the alluvial site was similar to that previously established in a glasshouse.
  • ? As observed in previous studies from younger trees, there is a potential to select genotypes, combining high productivity and high water-use efficiency, for growth in moderately drought-prone areas.
  •   相似文献   
    50.
    The Iwagaki oyster Crassostrea nippona may represent an aquaculture alternative to the Pacific oyster in Korea, Japan and China. In this study, morphology and immune-related functions of hemocytes of C. nippona were characterized using light microscopy and flow cytometry. Both light microscopy and flow cytometry indicated that C. nippona hemocytes are composed of three different types: granulocytes, hyalinocytes, and blast-like cells. Hyalinocytes were the most abundant and intermediate-sized cells, while granulocytes were the largest cells, containing many granules in the cytoplasm. Blast-like cells were characterized by a smaller size and very thin cytoplasm. Granulocytes were mainly engaged in phagocytosis and oxidative activities, although hyalinocytes also exhibited a certain level of immune-related activities. On the other hand, blast-like cells exhibited an absence of phagocytosis and extremely low oxidative capacity, suggesting that this subpopulation is not directly involved in cell-mediated immune response. The flow cytometry analyses carried out in the present study confirmed that granulocytes are the major hemocyte population involved in cellular defense of C. nippona, and allow for further studies on the impact of environmental stresses or pathogens on this alternative aquaculture species.  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