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   455篇
  免费   44篇
林业   30篇
农学   19篇
基础科学   6篇
  87篇
综合类   21篇
农作物   25篇
水产渔业   52篇
畜牧兽医   208篇
园艺   4篇
植物保护   47篇
  2024年   1篇
  2023年   13篇
  2022年   8篇
  2021年   21篇
  2020年   25篇
  2019年   25篇
  2018年   27篇
  2017年   26篇
  2016年   16篇
  2015年   17篇
  2014年   18篇
  2013年   29篇
  2012年   33篇
  2011年   31篇
  2010年   21篇
  2009年   20篇
  2008年   21篇
  2007年   16篇
  2006年   12篇
  2005年   9篇
  2004年   8篇
  2003年   13篇
  2002年   13篇
  2001年   7篇
  2000年   8篇
  1999年   12篇
  1998年   6篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   3篇
  1992年   5篇
  1991年   5篇
  1989年   2篇
  1988年   3篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1983年   2篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1973年   2篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1967年   1篇
  1963年   1篇
  1954年   1篇
排序方式: 共有499条查询结果,搜索用时 500 毫秒
21.
In this study, the effects of three diets were investigated to enhance Paracentrotus lividus production for commercial purposes. P. lividus were fed ad libitum for 80 days with: diet A—fresh Codium tomentosum Stackhouse, 1797; diet B—formulated using a jellified mix of macroalgae and vegetables, including C. tomentosum (20%), Coralina sp. Linnaeus, 1758 (17%), cabbage Brassica oleracea var. capitata Linnaeus, 1753 (30%), carrot Daucus carota Linnaeus, 1753 (30%) and agar (3%) as a gelling agent. Diet C consisted of maize Zea mays Linnaeus, 1753 (56%) and New Zealand spinach Tetragonia tetragonoides (Pallas, 1781) Kuntze, 1891 (44%). Their effects on the gonadal and somatic growths, gonadosomatic index (GI) and gametogenesis were evaluated, as well as on the total lipid content and fatty acid composition of sea urchin's gonads. Diet A provided high values of eicosapentaenoic acid (EPA). Gonads of sea urchins fed with diet A were found mostly in growth and maturation stages of gametogenesis and showed the lowest lipid content. Sea urchins fed with diet B presented their gonads in the reabsorption stage and had the highest values of omega‐3 polyunsaturated fatty acids (PUFAs). Sea urchins fed with diet C were in the early stages of gametogenesis and had the highest values of lipid content, plus omega‐6 PUFAs. Once as an ingredient in a balanced mix with vegetables, C. tomentosum can be a key factor to the development of new promising high‐quality and low‐cost feed for P. lividus roe enhancement.  相似文献   
22.
23.
Pharmacokinetic and clinical effectiveness of liposome-encapsulated N-methylglucamine antimoniate (LMA) was performed in dogs suffering from experimental leishmaniosis. LMA was compared with N-methylglucamine antimoniate (MGA), the same drug in its free form. Sb plasma concentrations for LMA were always higher than those for MGA. Mean residence time (MRT), half-life time (t(1/2)) and clearance (Cl) showed that Sb was eliminated slower after liposome administration. The high volume of distribution (Vd) obtained with LMA suggests that Sb could achieve therapeutic concentrations in parasite-infected tissues. Average plasma concentration at steady state (Css(ave)) shows that Sb body concentrations after LMA treatment (9.8 mg/kg Sb, each 24h) would be effective in Leishmania infantum canine infection. Comparing LMA with MGA in a 1-year follow-up we observed no relapses for LMA and total protein and gammaglobulin concentrations were within normal range, while for MGA both began to rise 3 months after treatment. Use of antimonial liposomal formulations may restore effectiveness to an existing drug and reduce toxicity.  相似文献   
24.
A 6-year old Salz ram was presented with a history of poor body condition, progressive gait abnormalities, pelvic limb lameness, and difficulty with copulation. Based on the history, clinical signs, hip palpation, and radiography, a diagnosis of hip dysplasia, previously unreported in sheep, was made.  相似文献   
25.
26.
The effect was studied of an acute and non-persistent hyperglycaemia on the serum fructosamine and blood glycated haemoglobin concentrations in canine samples. Five dogs were given glucose solution intravenously and blood samples were taken from each dog before and at 5, 15, 30, 60 and 120 min and 24 h after the infusion. There was an intense hyperglycaemia 5 min after the injection was given, but no statistically significant differences in the serum fructosamine and glycated haemoglobin were observed. It was concluded that an acute and transient hyperglycaemia does not cause significant changes in the glycated haemoglobin and fructosamine concentrations in healthy dogs.  相似文献   
27.
Off flavours in pork sometimes produce tastes such as sourness, fishy, metallic or other non‐typical flavours and are often caused by low pH. Loss of function mutations in flavin containing mono‐oxygenase 3 (FMO3) are known to be associated with a fishy off flavour in both chicken eggs and cow's milk and a similar autosomal recessive disorder is present in humans resulting in a fishy odour. FMO3 is a member of a gene family that is clustered on human chromosome 1. Comparative mapping suggested that FMO3 and the remaining FMO genes (ex. FMO1 and FMO5) might map to the orthologous region on pig chromosome 9 (SSC9) where a quantitative trait locus (QTL) for off flavour was previously identified. Primers were designed to amplify FMO1, FMO3 and FMO5 gene fragments and several SNPs were discovered and genotyping tests developed. The genotypes from the Iowa State University Berkshire × Yorkshire resource population were used to linkage map FMO1 and FMO3 to SSC9 and FMO5 to pig chromosome 4 (SSC4). QTL and associations analyses were performed using the map containing FMO1 and FMO3. Results demonstrated that FMO3 and FMO1 mapped less than 1 cM away from the peak for the off flavour QTL previously detected on SSC9 and provide indications of an association between the FMO3 polymorphism and off flavour in pork.  相似文献   
28.
The recent decline of Mediterranean oak woodlands in SW Iberian Peninsula is related to insect pests which affect both cork oak (Quercus suber) and holm oak (Quercus rotundifolia). We identified twenty-six bird species as potential regular predators of twenty major pests by reviewing the diet of breeding, wintering and resident species in this ecosystem. Foraging guilds are strongly associated with predation at distinct stages of the pests’ life-cycle: ground-foragers prey on overwintering pupae and larvae of seed-borers, tree-foragers prey on eggs, larvae and pupae of defoliating and wood-boring pests, and aerial-sweepers prey on airborne imagines. Bird predation can cover the complete life-cycle of pest species because different species may be complementary due to a dissimilar exploitation of foraging niches and periods. Small generalist tree-foraging passerines are important pest predators given their high densities and widespread distribution in Mediterranean oak woodlands, but management practices can have a significant negative effect in their populations.  相似文献   
29.
Foot and mouth disease (FMD) is a highly transmissible viral infection of cloven hooved animals associated with severe economic losses when introduced into FMD-free countries. Information on the impact of the disease in FMDV-endemic countries is poorly characterised yet essential for the prioritisation of scarce resources for disease control programmes. A FMD (virus serotype SAT2) outbreak on a large-scale dairy farm in Nakuru County, Kenya provided an opportunity to evaluate the impact of FMD on clinical mastitis and culling rate. A cohort approach followed animals over a 12-month period after the commencement of the outbreak. For culling, all animals were included; for mastitis, those over 18 months of age. FMD was recorded in 400/644 cattle over a 29-day period. During the follow-up period 76 animals were culled or died whilst in the over 18 month old cohort 63 developed clinical mastitis. Hazard ratios (HR) were generated using Cox regression accounting for non-proportional hazards by inclusion of time-varying effects. Univariable analysis showed FMD cases were culled sooner but there was no effect on clinical mastitis. After adjusting for possible confounders and inclusion of time-varying effects there was weak evidence to support an effect of FMD on culling (HR = 1.7, 95% confidence intervals [CI] 0.88-3.1, P = 0.12). For mastitis, there was stronger evidence of an increased rate in the first month after the onset of the outbreak (HR = 2.9, 95%CI 0.97-8.9, P = 0.057).

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0173-4) contains supplementary material, which is available to authorized users.  相似文献   
30.
Desneux  Nicolas  Han  Peng  Mansour  Ramzi  Arn&#;  Judit  Br&#;vault  Thierry  Campos  Mateus R.  Chailleux  Anais  Guedes  Raul N. C.  Karimi  Javad  Konan  Kouassi Arthur J.  Lavoir  Anne-violette  Luna  Mar&#;a G.  Perez-Hedo  Meritxell  Urbaneja  Alberto  Verheggen  Fran&#;ois J.  Zappal&#;  Lucia  Abbes  Khaled  Ali  Abid  Bayram  Yunus  Cantor  Fernando  Cuthbertson  Andrew G. S.  De Vis  Raf  Erler  Fedai  Firake  Dnyaneshwar M.  Haddi  Khalid  Hajjar  M. Jamal  Ismoilov  Khasan  Jaworski  Coline C.  Kenis  Marc  Liu  Hao-tian  Madadi  Hossein  Martin  Thibaud  Mazih  Ahmed  J. Messelink  Gerben  Mohamed  Samira A.  Nofemela  Robert S.  Oke  Abiola  Ramos  C&#;sar  Ricupero  Michele  Roditakis  Emmanouil  Shashank  Pathour R.  Wan  Fang-Hao  Wang  Ming-hui  Wang  Su  Zhang  Yi-Bo  Biondi  Antonio 《Journal of pest science》2022,95(1):17-39
Journal of Pest Science - The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), has invaded most Afro-Eurasian countries and is threatening worldwide tomato...  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