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   117篇
  免费   1篇
林业   12篇
农学   7篇
基础科学   1篇
  21篇
综合类   15篇
农作物   4篇
水产渔业   11篇
畜牧兽医   26篇
园艺   7篇
植物保护   14篇
  2023年   1篇
  2022年   7篇
  2021年   4篇
  2020年   7篇
  2019年   9篇
  2018年   2篇
  2017年   4篇
  2016年   5篇
  2015年   1篇
  2014年   10篇
  2013年   6篇
  2012年   7篇
  2011年   13篇
  2010年   4篇
  2009年   3篇
  2008年   6篇
  2007年   4篇
  2006年   3篇
  2005年   8篇
  2004年   6篇
  2003年   1篇
  2002年   3篇
  2000年   1篇
  1996年   1篇
  1990年   1篇
  1970年   1篇
排序方式: 共有118条查询结果,搜索用时 15 毫秒
21.
An 8‐week feeding trial was conducted to investigate the effects of dietary lipid levels on growth performance, fatty acid profile and fecundity in the oriental river prawn Macrobrachium nipponense. Five isonitrogenous experimental diets were formulated with graded lipid levels [A (5.02%), B (5.98%), C (6.91%), D (7.91%) and E (8.89%) respectively]. The results indicated that the values of body weight gain, specific growth rate, protein efficiency ratio and protein retention presented a similar trend of increasing first and then decreased with increasing dietary lipid levels. Furthermore, prawns fed diets containing 6.91% lipid showed the best values on these parameters among all the treatments. EPA, DHA and n‐3/n‐6PUFA contents showed associated increasing with the increase in lipid deposition of prawn muscle. The activities of hepatopancreatic amylase, protease and lipase were also significantly (p < .05) improved by dietary 6.91% lipid. Increasing dietary lipid levels could not suppress early maturation with no differences detected in berried females throughout the feeding trial. Significant lower relative fecundity may contribute to describing the dietary moderate lipid level (6.91%) could promote the growth of spawners and decrease spawning quantity. The recommendation dietary lipid requirement, estimated by the broken‐line model based on specific growth rate against dietary lipid levels, was 7.19% of the dry matter for M. nipponense.  相似文献   
22.
Tuberculosis (TB) is a chronic inflammatory and zoonotic disease caused by Mycobacterium tuberculosis complex (MTBC) members, affecting several domestic animals, wildlife species and humans. The preliminary investigation was aimed to detect antibody against MTBC among indigenous wildlife which are free-ranged wild boar, free-ranged wild macaques and captive Asian elephants in selected areas of Selangor and elephant conservation centre in Pahang, respectively. The results indicate that MTBC serodetection rate in wild boar was 16.7% (7.3–33.5 at 95% confidence interval (CI)) using an in-house ELISA bPPD IgG and 10% (3.5–25.6 at 95% CI) by DPP®VetTB assay, while the wild macaques and Asian elephant were seronegative. The univariate analysis indicates no statistically significant difference in risk factors for sex and age of wild boar but there was a significant positive correlation (P<0.05) between bovine TB in dairy cattle and wild boar seropositivity in the Sepang district.  相似文献   
23.
Poultry manure (PM) has been traditionally applied to crops for decades as an organic fertilizer, because it is a good and balanced source of plant nutrients. Its effect on plant growth and yield has been widely investigated and is well known. However, there has been little effort to relate elemental compositions of the manure applied to their concentrations in the plants. The objective of this study was to examine the effects of PM on the growth, and essential and non-essential element composition of pepper (Capsicum annuum) leaves and also fruits. Pepper plants were grown in soil with 0, 10, 20, and 40 g kg?1 PM under greenhouse conditions. Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), silicon (Si), aluminum (Al), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), molybdenum (Mo), chloride (Cl), nickel (Ni), bromine (Br), rubidium (Rb), strontium (Sr), barium (Ba), lanthanum (La), and cerium (Ce) in leaves at the flowering stage and in fruits were determined by polarized energy dispersive X-ray fluorescence (PEDXRF). Poultry manure fertilization significantly improved pepper shoot growth and also fruit yield, and increased leaf and fruit P concentrations but not N, K, Mg, Si, Al, Ni, and Fe. Leaf Ca was significantly reduced by increased rate of PM application. Applied PM increased the concentrations of leaf and fruit Zn and Cl. Poultry manure applications had a positive effect on the concentrations of leaf Cu, and fruit Mn. The concentrations of Rb and Ce in fruits and Br in fruit and leaves were increased by PM treatments. Applied PM levels had no clear effect on the concentrations of Ba and La in pepper leaves. The leaf Ba was the highest with 10 g kg?1 PM, and leaf La was higher in 20 and 40 g kg?1 PM treatments than in the control.  相似文献   
24.
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   
25.
European Journal of Plant Pathology - In the past two decades, viruses in the genera Crinivirus and Begomovirus, transmitted by whiteflies, have emerged as threatening diseases to cucurbit...  相似文献   
26.
Aquaculture International - This study investigated the effects of biochar application on the bacterial community structure in bioflocs and intestines of Oreochromis niloticus cultured in a biofloc...  相似文献   
27.
米泽民  Yusuf  Mahamood  Alh.  Aliyu  Udubo  Mailambu  Waziri 《中国农学通报》2011,27(13):223-226
尼日利亚北方芒果是树体生长在雨季,而果实生长在旱季。需要在芒果生产中组织一套顺应当地的气候、适合当地生产条件的综合配套技术。为此笔者设计并进行试验。试验证明,在树形选择上以多主枝开心形和少主枝开心形为好;当年生枝梢的留枝量以280条/株为佳;在施肥和修剪上以2次施肥和2次修剪为技术路线的综合配套技术。为当地芒果生产水平的提高,制定相应的技术措施。  相似文献   
28.
The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was left fallow for fourteen years due to lack of funds. Topsoil was collected from plots that received three levels of cow dung (D), nitrogen (N) and phosphorus (P) in all possible combinations. The soils were analyzed for selected chemical properties. Except for significant effect of applied P on available P, sole application of cow dung, N or P had no significant effect on all the measured soil properties. The interaction of D and P significantly affected the mean values of exchangeable Ca, Mg, K and ECEC in the range of 1.12-1.96, 0.62-1.11, 0.37-0.64 and 2.82-4.11 cmol/kg respectively. The most important results were the ability of the plot that received neither D nor P to significantly increase these parameters than the plots that received only one of the treatments. The results show that the fallow period has changed the effects of application of organic and mineral fertilizers on the soil chemical properties under continuous cultivation by modifying them towards those of a native savanna Alfisol.  相似文献   
29.

Developing new tools for using low-quality irrigation waters is vital for the sustainability of irrigated agriculture and minimizing salt accumulation. Therefore, the present study focused on the interactive influence of irrigation treatments (magnetized (MT) and non-magnetized (NMT)) and water salinities (0.38, 1.5, 4.5, and 7.0?dSm?1) on soil salinity, water use efficiency, yield and morpho-physiological changes of Balk?z bean. A pot experiment was conducted in a randomized complete block design with three replications under the rain shelter condition. Irrigation water MT treatment increased fresh bean yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) by 21.35, 23.00 and 14.8%, respectively, while saturated soil salinity was reduced by 20%, compared to NMT treatments. The leaf area, stomata, and leaf succulence in green beans in the MT treatment significantly increased by 13.4, 23.9, and 3.3% compared with those in the NMT treatment. Stems of the bean crops were more sensitive to salinity stress followed by roots and leaves. The study revealed that irrigation with magnetically treated water manages salinity related yield loss through increased morphological features as well as osmotic and stomatal adjustments. In addition, the bean crops showed an ability to protect water in tissue against salinity toxicity up to 5.24?dSm?1 soil salinity level under magnetized saline water conditions. Finally, irrigation with magnetically treated 0.38?dSm?1 irrigation water can be recommended due to providing a higher yield, WUE, IWUE, and sustainable production under saline irrigation in water scarcity regions.

  相似文献   
30.
Veterinarians and veterinary technicians are at risk for occupational brucellosis. We described the risk factors of occupational brucellosis among veterinary personnel in Turkey. A multicenter retrospective survey was performed among veterinary personnel who were actively working in the field. Of 712 veterinary personnel, 84 (11.8%) had occupational brucellosis. The median number of years since graduation was 7 (interquartile ranges [IQR], 4–11) years in the occupational brucellosis group, whereas this number was 9 (IQR, 4–16) years in the non-brucellosis group (p < 0.001). In multivariable analysis, working in the private sector (odds ratio [OR], 2.8; 95% confidence interval [95% CI], 1.55–5.28, p = 0.001), being male (OR, 4.5; 95% CI, 1.05–18.84, p = 0.041), number of performed deliveries (OR, 1.01; 95% CI, 1.002–1.02, p = 0.014), and injury during Brucella vaccine administration (OR, 5.4; 95% CI, 3.16–9.3, p < 0.001) were found to be risk factors for occupational brucellosis. We suggest that all veterinary personnel should be trained on brucellosis and the importance of using personal protective equipment in order to avoid this infection.  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