全文获取类型
收费全文 | 383篇 |
免费 | 26篇 |
专业分类
林业 | 20篇 |
农学 | 25篇 |
77篇 | |
综合类 | 23篇 |
农作物 | 31篇 |
水产渔业 | 55篇 |
畜牧兽医 | 142篇 |
园艺 | 2篇 |
植物保护 | 34篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 25篇 |
2019年 | 28篇 |
2018年 | 25篇 |
2017年 | 23篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 25篇 |
2013年 | 19篇 |
2012年 | 26篇 |
2011年 | 26篇 |
2010年 | 21篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 20篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有409条查询结果,搜索用时 15 毫秒
141.
142.
A study was conducted in Chad to estimate the prevalence and the incidence of Trypanosoma vivax infection in herds of cattle from the Lake Chad area. The risk factors associated with disease were also identified. A random sample of 933 cattle from 17 herds was initially selected (January 1999, cold dry season). Cattle were identified by ear-tags and sampled in the rainy season (July 1999) and the cold dry season (January 2000). Each animal sampled was treated with diminazene aceturate (3.5mg/kg). Samples were examined for the presence of T. vivax using an antibody (indirect ELISA) and a parasite detection test (buffy-coat technique, BCT). Standardized questionnaires with information about the host and management practices were collected and evaluated for their association with seroprevalence (model 1) and parasitological prevalence (model 2) as indicator of host susceptibility to T. vivax infection. Risk factors were selected using two approaches: ordinary logistic regression (OLR) and generalized estimating equations (GEE) to account for within-herd correlation. The apparent prevalence was 1.6% using BCT and 42.3% with indirect ELISA. The true prevalence in the sample was estimated to (2.0%-8.0%) with two assumptions of BCT sensitivity. Overall, 58.8% (BCT) and 100.0% (ELISA) of the herds had a least one-positive animal. In January-July 1999, apparent monthly incidence was calculated at 0.24% in comparison with 0.76% for August 1999-January 2000. The true monthly incidence was estimated at 0.36%-1.43% for the first period and at 0.94%-3.78% for the second period. Risk factors associated with seroprevalence were age, race, a great number of small ruminants in the herd, and latitude and longitude of pasture area in the rainy season. Risk factors associated with BCT prevalence were duration of seasonal migration and longitude of pasture area in the rainy season. In conclusion, T. vivax is present and widely disseminated in the cattle herds of tse-tse free area of Lake Chad. Farm-level factors, particularly seasonal migration, should be considered as the main risk factors for infection and to host susceptibility to the parasite. 相似文献
143.
Biteau-Coroller F Gerbier G Stärk KD Grillet C Albina E Zientara S Roger F 《Veterinary microbiology》2006,118(1-2):57-66
In 1998, bluetongue (BT) was introduced in northern Africa and then extended to northern latitudes including the French island of Corsica. Following the outbreaks in Corsica in 2000 and 2001, cross-sectional studies and surveillances have been set up in Corsica and also in the southern part of mainland France, a disease-free area but considered at high risk because of its proximity. The surveillance was based on regular blood sampling of susceptible species and antibody detection by a commercial competitive ELISA kit (cELISA). The performance of this cELISA was evaluated on both field results obtained during the 2001 surveillance campaigns and experimental results. ROC analyses were carried out using RT-PCR results as gold standard for determining the infection status of animals. From all these sets of data, cut-off values optimising the diagnostic accuracy of the test were computed. Their values ranged around the manufacturer's 50% threshold from 41% to 63%. The area under the ROC curve obtained from field data was 0.843 (95% CI: 0.762-0.923). In all our results, it appeared also that the specificity of the cELISA test was always perfect if the cut-off was at least at 80%. This cELISA test does not seem sufficient to diagnose BT disease in animals with BT-like symptoms. However, complementary data are needed to better estimate sensitivity and specificity values of this BT test for its use either as a diagnostic tool in infected areas or as a screening test in BT-free areas. The use and validity of RT-PCR results as gold standard are discussed. As the lack of suitable data strongly limited the applicable analyses, a discussion based on the OIE recommendations about test evaluation is initiated. 相似文献
144.
Francis Alemawor Emmanuel Okpoti Kofi Oddoye Victoria P. Dzogbefia John H. Oldham Armstrong Donkoh 《Tropical animal health and production》2010,42(5):933-939
The purpose was to investigate the feeding value of fibrous cocoa pod husk (CPH) either fermented with Pleurotus ostreatus or supplemented with fibre-degrading multi-enzymes (Viscozyme®L?+?Pectinex®5XL) before inclusion in diets for 3-week-old finishing broilers. Growth performance and carcass yield of broilers fed diets containing 100, 200 or 300 g kg?1 of the P. ostreatus-fermented CPH or 100, 200 or 300 g kg?1 of the enzyme-supplemented CPH as well as a normal broiler finisher diet (control), were investigated in a 35-day feeding trial setup as a completely randomised design, with the seven treatments replicated three times. There were significant differences (P?0.05) among treatments for some of the parameters measured including growth-related indices, percent weights of abdominal fat, intestine, and gizzard. It was concluded that P. ostreatus-fermented dried CPH up to a level of 200 g kg?1 and enzyme-supplemented dried CPH up to a level of 100 g kg?1 could be included in broiler finisher diets without any deleterious effects. 相似文献
145.
Melinda J. Bodary Nathan Stone Steve E. Lochmann Emmanuel Frimpong 《Journal of the World Aquaculture Society》2004,35(4):489-497
Scientific information on baitfish effluents is important to provide a basis for the development of appropriate and cost-effective management practices that minimize environmental impacts. Effluents from 10 commercial golden shiner Notemigonus crysoleucas ponds in central Arkansas were sampled December 2000 through June 2001. Grab samples of the first and last 10% of pond volume were collected during intentional draining events. Effluents were sampled as they exited pond drainpipes and at the ends of drainage ditches just prior to stream discharge. Concurrent receiving stream samples were collected upstream and downstream of the discharge point. Total nitrogen (TN), total phosphorus (TP), 5-d biochemical oxygen demand (BODS ), and total suspended solids (TSS) of each sample were measured. Mean whole effluent concentrations for the first 10% were 36 mg TSS/L, 9 mg/L BOD5 , 2 mg TN/L, and 0.5 mg TP/L. The water quality of the first and last 10% of pond effluent were not significantly different ( P < 0.05). Filtering effluents through a 5-pm mesh screen did not significantly reduce nutrient concentrations. Serial fractionation of effluents resulted in small but significant decreases in TSS concentrations in samples filtered through the 10, 8, and 5-μm meshes ( P < 0.05). Effluent discharge through farm ditches generally did not improve effluent water quality. Effluents collected at ditch ends were significantly less than drainpipe samples in BOD, concentrations only ( P < 0.05). Limited data on receiving stream water quality indicated that only TP concentrations were greater in pond effluents than in receiving streams. Overall, baitfish pond effluents are similar in composition to effluents of other phytoplankton-based pond production systems. 相似文献
146.
De Bosschere H Roels S Dechamps P Vanopdenbosch E 《Veterinary journal (London, England : 1997)》2007,173(2):449-451
It is commonly accepted that scrapie-resistance and -susceptibility in sheep are genetically controlled. Consequently, the selection of sheep with scrapie-resistant genotypes is currently one of the most important objectives of the sheep breeding associations. However, during the last two years, new data have become available on transmissible spongiform encephalopathy (TSE) cases in TSE-resistant sheep in several European Union member states. The present paper describes the first Belgian natural "atypical" TSE case in a sheep with a scrapie-resistant genotype (ARR/ARR) detected via active surveillance. No other infections or diseases were detected in the source flock. The continued finding of new "atypical" TSE cases in sheep with scrapie-resistant genotypes undermines the purpose and efficacy of the breeding programs. 相似文献
147.
Gentallan Renerio P. Bartolome Michael Cedric B. Cejalvo Reneliza D. Timog Emmanuel Bonifacio S. Altoveros Nestor C. Borromeo Teresita H. Endonela Leah E. 《Genetic Resources and Crop Evolution》2021,68(7):2767-2773
Genetic Resources and Crop Evolution - Combretum indicum (L.) DeFilipps seeds have anthelmintic properties and are recognized to be medicinal; however, the array of their morphological characters,... 相似文献
148.
The article, Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility by Jae-Woo Choi, Kyu-Sang Kwon, Soonjae Lee, Byungryul An, Seok-Won Hong, Sang-Hyup Lee, is replete with some fundamental scientific flaws which have the potential to misinform readers. This comment seek to correct these flaws. 相似文献
149.
Thomas Kichey Bertrand Hirel Emmanuel Heumez Frédéric Dubois Jacques Le Gouis 《Field Crops Research》2007
In wheat, nitrogen (N) uptake and remobilisation after flowering contributes largely, in Northern countries, to grain yield and grain protein content. The aim of our study was first to estimate the proportion of N taken up and remobilised to the grain as well as their relative efficiency using 15NO3−-labelling at flowering. The validity of the technique was assessed in comparison to the N budget calculation method on five winter wheat cultivars grown for 2 years at low and high fertilization input. We estimated that on average 71.2% of grain N originates from remobilisation with significant genotypic differences. Among the five genotypes, significant differences were also found for both N remobilisation efficiency (from 69.8 to 88.8%) and N translocation efficiency (from 89.7 to 93.4%). In parallel, during 1 year, we monitored physiological markers representative of N assimilation and recycling at two sampling dates during the grain filling period. We then examined if there was any relationship between these physiological markers, N absorption and remobilisation estimates and agronomic traits related to yield and grain N content. Nitrate reductase (NR) activity was highly correlated to N absorbed post-flowering and to grain protein content. Glutamine synthetase (GS) activity was even more highly correlated than NR activity to the amount of N remobilised and grain yield. The use of physiological traits such as NR and GS activities as markers of the wheat N status is discussed. 相似文献
150.
Kinetics of microbial phosphorus uptake in cultivated soils 总被引:5,自引:0,他引:5
Fritz Oehl Astrid Oberson Mirjam Probst Andreas Fliessbach Hans-Rudolf Roth Emmanuel Frossard 《Biology and Fertility of Soils》2001,34(1):31-41
Knowledge about the role of microorganisms in P cycling at conditions of constant soil respiration rates and constant size of microbially bound P is lacking. To study the kinetics of microbial P uptake and cycling under such conditions, soils differing in biological activity were 33PO4 labelled by introducing a carrier-free tracer solution and incubated for 56 days. The 33PO4 incorporation into the fraction of microbial P releasable by chloroform treatment (Pchl) was assessed and the isotopic composition [=specific activity (SA); SA=33PO4/31PO4] of Pchl and soil solution P compared. Soils were taken from a 20-year-old field experiment including a non-fertilised control (NON), a minerally fertilised conventional (MIN) and two organic farming systems [bio-organic (ORG); bio-dynamic (DYN)]. Tracer P incorporation continuously increased during incubation in DYN, ORG and MIN soils. It decreased in the order DYN>ORG>MIN, with differences in 33PO4 uptake between the farming systems being higher than suggested by the differences in the amount of Pchl. In the P-deficient NON soil, the highest initial incorporation of tracer P was found, but no additional uptake could be detected thereafter. In all soils, the SA of Pchl converged to the SA of the soil solution with increasing time. Since Pchl remained almost constant during the experiment, the findings suggest an intensive uptake of P from the soil solution into Pchl and concomitant release of P back to the soil solution and, thus, a rapid cycling through Pchl. Intensive P cycling between Pchl and the soil solution was confirmed in an additional experiment where microbial activity was stimulated by glucose and N additions. 相似文献