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   266篇
  免费   19篇
林业   23篇
农学   18篇
基础科学   2篇
  41篇
综合类   19篇
农作物   30篇
水产渔业   26篇
畜牧兽医   94篇
园艺   6篇
植物保护   26篇
  2024年   1篇
  2023年   1篇
  2022年   4篇
  2021年   10篇
  2020年   18篇
  2019年   17篇
  2018年   23篇
  2017年   21篇
  2016年   13篇
  2015年   17篇
  2014年   15篇
  2013年   20篇
  2012年   16篇
  2011年   20篇
  2010年   4篇
  2009年   9篇
  2008年   8篇
  2007年   3篇
  2006年   5篇
  2005年   6篇
  2004年   6篇
  2003年   5篇
  2002年   2篇
  2001年   3篇
  2000年   4篇
  1999年   3篇
  1998年   1篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1992年   2篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1984年   5篇
  1983年   1篇
  1982年   1篇
排序方式: 共有285条查询结果,搜索用时 781 毫秒
31.

A total of 1000 clinically healthy small ruminants comprising 500 sheep and 500 goats from five districts within Riyadh Province in Saudi Arabia were investigated by routine Giemsa staining for hematozoan parasites. Out of these, 100 sheep and 95 goat samples were investigated by PCR using three pairs of hemoprotozoan-specific primers. Based on microscopic examination, 33.2% of sheep and 25.2% of goats were found infected with hemoprotozoan parasites, while PCR detected hematozoan infection in 46% of sheep and 33.7% of goats. Extensive molecular characterization of hematozoan infection using six pairs of species-specific primers revealed the dominance of Theileria ovis, rather than any other species, which is recorded for the first time in small ruminants in Saudi Arabia. Prevalence of T. ovis in sheep and goats was found to be the highest in Riyadh (32, 48%) followed by AL-Kharj (31, 35%), Ad-Dawadimi (31, 33%), AL-Majmaah (15, 27%), and Rumah (17, 23%). The highest parasite prevalence was recorded in the 3 years of age and >?4 years of age ruminants, while the lowest prevalence was recorded in <?1 year of age ruminants. No noticeable differences in parasite prevalence between male or female ruminants were recorded. Partial sequencing of 18S rRNA gene revealed the infection of the studied ruminants with four new isolates of T. ovis. Further characterization of the pathogenicity and the clinical effects of these T. ovis isolates in sheep and goats is highly needed. The current results can be helpful in protecting and improving livestock industry in the countries that depend on a high number of small ruminants.

  相似文献   
32.
Veterinary Research Communications - Avian polyomavirus (APV) infection, also called as budgerigar fledgling disease (BFD) causes various health problems in many psittacine species which may cause...  相似文献   
33.
Tropical Animal Health and Production - Mastitis is the inflammation of the mammary gland due to microbial infiltration causing a reduced mammary function. This study aims at developing a vaccine...  相似文献   
34.
This study was conducted in 2007 and 2008 in order to determine the effects of irrigation frequency on the yield and quality parameters of dwarf trees of the apple cultivar ‘Gala, Galaxy’ in the first and second year of cultivation. Irrigation water was applied at 3?, 5?, 7?, and 10-day intervals as much as the amount of water consumed from the field capacity. Statistical analysis revealed that the effects of irrigation frequency on yield were significant. Since the trees used in the experiment showed mainly vegetative growth, the effects of irrigation frequency on the fruit quality characteristics varied. Irrigation water amount was applied as 355.7–446.5 mm and 359.2–538.9 mm to the experimental treatments in 2007 and 2008, respectively. The evapotranspiration measured was in the range 400.7–491.5 mm in 2007 but in the range 440.2–600.5 mm in 2008, while the yields in the same years ranged from 1.54 to 2.84 t ha?1 and from 2.61 to 6.06 t ha?1. Water use efficiency varied between 2.40 and 4.80 t ha?1mm?1 in the first year of the experiment but between 3.45 and 7.08 t ha?1mm?1 in the second year. The I2 treatment, in which the highest yield and water use efficiency were recorded in both years of the experiment under the experimental conditions, was determined as the irrigation scheduling.  相似文献   
35.
Precipitation events were collected during the period from October 1996 to April 1997 from two sites in the city of Amman, Jordan. The samples were analyzed for major cations (Na+, K+, Ca2+, Mg2+ and NH4+), major anions (F-, Cl-, NO3- and SO42-), in addition to heavy metals (Cu2+, Cd2+, Zn2+, and Pb2+). High levels of Ca2+ and SO42- were observed. The results were comparable with some regional values and they indicate that about 58% of Na+ and Cl- are of marine origin, while Ca2+, K+ and a large fraction of SO42- are of soil dust origin. Heavy metals were detectable in most of the samples, zinc showed the highest concentrations. Significant correlation was obtained between zinc and lead, which may indicate automobile emission source.  相似文献   
36.
This experiment was carried out to evaluate the effects of the probiotic, Lactobacillus acidophilus , on the growth performance, haematology parameters and immunoglobulin concentration in African catfish Clarias gariepinus fingerling. Two experimental diets were formulated to contain 35 g kg−1 crude protein and 10 g kg−1 lipids accordingly and fed three times daily for 12 weeks to 25 C. gariepinus fingerlings per fibreglass tank in 12 replicates each. The control diet was prepared with no probiotic supplementation whereas the second diet was prepared supplemented with a probiotic, L. acidophilus , containing about 3.01 × 107 colonies/g of diet. The results show that growth performance [specific growth rate (SGR) and relative growth rate (RGR)], nutrient utilization [protein efficiency ratio (PER) and feed conversion ratio (FCR)] and survival were significantly ( P <0.05) higher in fish maintained on the probiotic-supplemented diet compared with those on the control diet. Haematology parameters (packed cell volume, haemoglobin, erythrocyte sedimentation rate, red blood cell and white blood cell, total serum protein, Ca2+, Mg2+, Cl, glucose and cholesterol) and total immunoglobulin concentrations were also significantly better in fish fed the probiotic-supplemented diet than in the control. Although the water quality parameters monitored were better in the fish fed the probiotic-supplemented diet than in the control, the parameters were not significantly different ( P >0.05). From the results of this experiment, we conclude that L. acidophilus can be used as a probiotic agent in African catfish culture, to enhance fish health, survival and better feed efficiency and growth performance.  相似文献   
37.
38.
Methanolic extracts of 79 Malaysian plants representing 42 families were assessed for antinematodal activity against Bursaphelenchus xylophilus using a fungal-feeding assay. Extracts of 27 plants from 19 families showed antinematodal activity, while 52 species were inactive. Five extracts (Sauropus androgynus, Eugenia polyantha, Areca catechu, Piper betle and Piper nigrum) exhibited very strong activity against Bursaphelenchus xylophilus at a minimum effective dose (MED) of 0·625 mg per ball. Strong antinematodal activity (MED: 1·25–2·5 mg per ball) was shown by the extracts of Spondias cyntherea, Codiageum variegatum, Euodia glabra and Cicca acida. Eleven extracts (Carica papaya, Ipomoea aquatica, Ocimum basilicum, Leea gigantea, Pithecellobium jiringa, Crypteronia paniculata, Myristica fragrans, Murraya koenigii, Leucaena leucocephala, Melastoma malabathricum and Morinda citrifolia) demonstrated moderate activity between MED of 5 and 10 mg per ball, and weak activity was observed in seven extracts (Ipomoea batatas, Cymbopogon citratus, Garcinia atroviridis, Psophocarpus tetragonolobus, Tamarindus indica, Allium odorum and Stenochalaena palustris). © 1997 SCI  相似文献   
39.
40.
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   
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