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   81篇
  免费   4篇
林业   5篇
农学   1篇
  16篇
农作物   7篇
水产渔业   11篇
畜牧兽医   25篇
园艺   6篇
植物保护   14篇
  2022年   4篇
  2021年   2篇
  2020年   3篇
  2019年   6篇
  2018年   6篇
  2017年   3篇
  2016年   7篇
  2015年   1篇
  2014年   4篇
  2013年   4篇
  2012年   11篇
  2011年   4篇
  2010年   1篇
  2009年   6篇
  2008年   2篇
  2007年   5篇
  2006年   3篇
  2005年   1篇
  2004年   6篇
  2003年   1篇
  2002年   2篇
  2000年   1篇
  1999年   1篇
  1967年   1篇
排序方式: 共有85条查询结果,搜索用时 156 毫秒
1.
The incidence, severity and distribution of six viruses infecting capsicum were determined in the main growing areas of Turkey during the 2004 growing season. The surveys covered 50 randomly selected capsicum fields from four different areas in south-east Anatolia and the eastern Mediterranean region. 515 samples were individually collected and tested by DAS-ELISA for Cucumber mosaic cucumovirus (CMV), Alfalfa mosaic alfamovirus (AMV), Potato X potexvirus (PVX), Potato Y potyvirus (PVY), Pepper mild mottle tobamovirus (PMMoV) and Tobacco etch potyvirus (TEV). 64.8% of ELISA-tested capsicum samples (334 out of 515) were infected by one (41.7%) or more (23.1%) viruses. PVY was the most widespread (26.4%), followed by PVX (25.8%), AMV (25.2%), TEV (23%), PMMoV (9.1%) and CMV (8.3%). Surprisingly high AMV infection was found in three areas (Kahramanmaraş, Şanlıurfa and Gaziantep) where AMV is reported for the first time in this study. However, AMV was not detected in Hatay. PMMoV is another new virus, in all the tested areas.  相似文献   
2.
3.
In this article the effect of different nitrogen fertilizer application on the availability of zinc (Zn) content in non calcic brown forest soil was investigated. For this purpose increasing rates of NH4Cl, (NH4)2S04; NH4N03 and Ca(N03)2.4H20 fertilizers were applied for having different physical and chemical properties in two soil samples. An incubation experiment was carried out over 4 months. The available Zn content of the soils was determined each month. According to the results the highest available Zn content of the soils was obtained from NH4Cl applied to the soils followed by (NH4)2S04; NH4N03 and Ca(N03)2.4H20 application to soil. At the end of the experiment the average available Zn content of non calcic brown forest soils for NH4Cl, (NH4)2S04; NH4N03 and Ca(N03)2.4H20 fertilizers are 0.93, 0.91, 0.88 and 0.77 mg kg?1, respectively.  相似文献   
4.
In order to evaluate the influence of different N rates on percent N derived from fertilizer (%Ndff) at different growth stages, on yields and the percent N use efficiency (%NUE) values of two winter wheat varieties (durum and bread), field experiments on fallow were carried out at four different locations in Central Anatolia, in the 1991–1992 and 1992–1993 growing seasons. At each site the rates of N (0, 40, 80 and 120?kg N/ha) were applied as ammonium sulphate [(NH4)2SO4] using a Latin Square experimental design with four replicates. The total amounts of N fertilizer were applied once after seedling emergence at all experimental sites. Labelled (15NH4)2SO4 fertilizer was applied to sub-plots from which %Ndff values were determined at tillering, booting, grain filling, and harvest stages. Yield sub-plots received unlabelled (NH4)2SO4 from which total dry matter (seed and straw) and N yields were determined. Also the %NUE values were calculated by the 15N and "difference" methods at the harvest stage. Stored soil moisture at 0–90?cm depth, evapotranspiration and water use efficiency values were calculated as well. The results obtained showed that (1) Gerek-79 variety used both the applied N fertilizer and the available soil moisture more efficiently, (2) the percent NUE values obtained overall were generally less than 20 for both varieties and (3) with the 15N method, less variable %NUE values were obtained in comparison to the difference method.  相似文献   
5.
Randomly Amplified Polymorphic DNA markers were used to determine the genetic relationships among Turkish lentil cultivars and breeding lines. Fourteen cultivars and thirteen breeding lines were evaluated to determine genetic variability using nine random 10-mer primers (among 45 primers). Forty-one reproducible bands were obtained, 54% of which were polymorphic. Genetic distances among cultivars and breeding lines were obtained from the simple matching coefficients (SM). The lowest genetic distance was observed between the cultivars of Ali Dayi and Kafkas with 5.0%, while ‘Seyran-96’ and ‘Ozbek’ had the highest genetic distance with 58.3%. An unweighted pair-group method with arithmetic averages (UPGMA) cluster analysis was performed on the distance matrix using Phylip software. The dendrogram clearly showed two distinct groups. The first group is composed of Akm 565 and Akm 563. The second group contains all the cultivars and remaining eleven breeding lines.  相似文献   
6.
We evaluated,for the first time in Turkey,the productivity of a feller buncher during clear-cut operations of two Brutian pine stands located in Canakkale,northwestern Turkey with different diameter classes and terrain conditions.In the first stand with 24.6 cm average DBH,the feller buncher cut full trees and moved them to roadside.In the second stand with 34.3 cm average DBH,the feller buncher cut trees in two stages due to their larger diameters and the relatively steep and rough terrain conditions of the site.The effects of specific stand features,DBH and tree height measurements were assessed through statistical analysis in relation to productivity.The results indicate that the average productivity for the first stand was about 118 m^3h^-1,while it was about 80 m3h-1 in the second stand.Even though tree diameter and volume were higher in the second stand,productivity decreased by32.3%due to extra time spent on the two-stage cutting operation.The results revealed that harvesting operations should be planned carefully and the right equipment selected by accounting for different tree sizes,terrain conditions and machine specifications in order to better understand their effects on production.  相似文献   
7.
The objective of the study was to evaluate the interval from onset of oestrus to time of artificial insemination (AI) to obtain the optimum pregnancy rate with sex-sorted semen in Holstein heifers. Heifers in oestrus were detected and inseminated only by using heat–rumination neck collar comprised electronic identification tag at the age of 13–14 months. Heifers (n = 283) were randomly assigned to one of three groups according to the timing of insemination at 12–16 hr (G1, n = 97), at 16.1–20 hr (G2, n = 94) and at 20.1–24 hr (G3, n = 92) after reaching the activity threshold. The mean duration of oestrus was 18.6 ± 0.1 hr, and mean peak activity was found at 7.5 ± 0.1 hr after activity threshold. The mean interval from activity threshold to ovulation was 29.4 ± 0.4 hr. The overall pregnancy per AI (P/AI) was 53.0% at 29–35 days and 50.9% at 60–66 days after AI. There was a significant reduction between G1 (13.8 ± 1.4 hr) and G3 (7.9 ± 1.4 hr) related to the intervals from AI to ovulation time. Sex-sorted semen resulted in significantly higher P/AI at 29–35 days when heifers inseminated in G3 (60.9%) after oestrus than those inseminated in G1 (49.5%) and G2 (48.9%). In terms of fertility, when the temperature–humidity index (THI) was below the threshold value (THI ≤65) at the time of AI, there was a tendency (≤65; 57.2% vs. > 65; 47.1%) for high pregnancy rate. There was no effect of sire on P/AI. In addition, the interaction of the technician with the time of AI was found significant, and three-way interaction of technician, sire and time of AI was tended to be significant on pregnancy rate. Thus, in addition to delaying the time of insemination (between 20.1 and 24 hr) after oestrous detection, THI and experienced technician were also found to be critical factors in increasing fertility with the use of sex-sorted semen in Holstein heifers.  相似文献   
8.
Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of cassava bacterial blight (CBB) disease. CBB is a major constraint to cassava cultivation in Ghana. In this study, a survey was conducted in eight regions of Ghana to assess the presence of CBB disease. Out of the eight regions visited, CBB, though at different prevalence, was observed in five regions. Cassava plants samples showing suspected bacterial blight symptoms were collected for analysis by Polymerase Chain Reaction (PCR). The results of the analysis showed that Ashanti region had the highest prevalence in percentage of CBB, which recorded (70%), followed by Volta region (60%); Brong Ahafo region (40%); Eastern region (40%) and Greater Accra region (20%). Morphological examination of the putative pathogen was carried out on Cefazolin trehalose agar (CTA) and Nutrient agar (NA) media. The isolates were subjected to conventional PCR using Xanthomonas genus specific primer, RST2/RST3, Xam specific Variable Number Tandem Repeat (VNTRs) loci, XaG1_67F/R and X-gumD primers, which produced 840, 446 and 402 bp, respectively. The isolates also tested positive with SYBR Green fluorescent dye, using Real-time PCR. The resulting PCR products were sequenced and analyzed using a BLASTn program, which revealed homology between 93 and 100% with several other Xam strains retrieved from GenBank nucleotide database. The pathogenicity test of the isolates on the susceptible Esam cassava variety produced symptoms typical of Xam and the pathogen was consistently re-isolated from the inoculated cassava plants and thereby satisfying the Koch’s postulates.  相似文献   
9.
The aim of this study was to determine the effects of early feed restriction on performance, carcass characteristics, meat and liver composition, some blood parameters, H-L ratio, antibody titers against SRBC and tonic immobility duration in broilers. One hundred ninety male chicks (Ross 308) were randomly allocated into two treatment groups each of 95 chicks. Broilers in one treatment fed ad libitum until 42 day of age, however in other treatment, broilers were deprived of feed for 4 h per day from 7 to 21 day. Body weight, feed consumption, feed to gain ratio, carcass characteristics and the percentage of examined organs except heart were not statistically significant in groups. Percentage of heart was higher (p < 0.05) in broilers fed ad libitum. At 41 d of age, H-L ratio (p < 0.05) and TI duration (p = 0.001) were higher, serum glucose (p < 0.05) and triglyceride (p < 0.001) levels were lower in broilers fed ad libitum. Chemical composition of breast and thigh and also fat and ash of liver were not affected by early feed restriction. Moisture of liver (p = 0.001) was lower and protein of liver (p < 0.01) was higher in broilers fed ad libitum  相似文献   
10.
In this study, the effects of less-expensive protein sources replaced with soybean meal on growth performance, nutrient utilization and body composition of juvenile grass carp were investigated. For this purpose, a control diet containing 42% soybean meal was prepared. Cotton seed meal (CSM), sunflower meal (SFM) and corn meal (CM) were added to the experimental diets by replacing 100% of the soybean meal protein used in the control diet. All diets were iso-nitrogenous (40% crude protein) and iso-caloric (19.5?MJ?kg?1 gross energy). Each treatment had three replicates, and 20 juvenile grass carps (3.5?±?0.1?g, initial weight) were located in per replicate. The fish were fed to satiety three times in a day during 3?months at 26°C of water temperature in glass aquarium (45 l). The results of the study showed that the weight gain (308.6?C448.6%), specific growth rate (1.56?C1.89%/day), feed conversion rate (1.2?C1.9), protein efficiency ratio (1.32?C2.08), and apparent digestibility coefficients of protein (80.5?C89%) or sum of amino acids (80.5?C88.9%) were not significantly affected by the experimental diets, except diet CM. All of these values obtained for the diet CM were significantly lower than those of fish fed on the control, CSM and SFM diets. However, there were no significant differences between the lipid digestibility of the diets, and crude protein, lipid, and gross energy contents in the whole body of fish in experiments. In conclusion, CSM and SFM diets were highly utilized by juvenile grass carp, but not CM diet. These results combined with the remarkable acceptability of diets containing high levels of plant protein ingredients with identical growth performances of juvenile grass carp show clearly that dietary soybean meal level can be considerably reduced without any adverse consequence in terms of somatic growth and nitrogen utilization.  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