全文获取类型
收费全文 | 16524篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
林业 | 3628篇 |
农学 | 1295篇 |
基础科学 | 140篇 |
2772篇 | |
综合类 | 717篇 |
农作物 | 2100篇 |
水产渔业 | 1787篇 |
畜牧兽医 | 1084篇 |
园艺 | 1123篇 |
植物保护 | 1880篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 2746篇 |
2017年 | 2705篇 |
2016年 | 1185篇 |
2015年 | 68篇 |
2014年 | 18篇 |
2013年 | 23篇 |
2012年 | 800篇 |
2011年 | 2133篇 |
2010年 | 2106篇 |
2009年 | 1263篇 |
2008年 | 1321篇 |
2007年 | 1578篇 |
2006年 | 34篇 |
2005年 | 114篇 |
2004年 | 103篇 |
2003年 | 156篇 |
2002年 | 61篇 |
2001年 | 6篇 |
2000年 | 41篇 |
1999年 | 1篇 |
1995年 | 1篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1977年 | 4篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
91.
A longitudinal study was done to monitor incidence of livestock diseases in ranch and pastoral herds around Lake Mburo National
Park, in South-western Uganda with a high level of wildlife (impala and zebra) and livestock (cattle and goats) interactions.
East Coast Fever (ECF), abortions, helminthosis and starvation due to drought were major livestock disease problems encountered.
ECF was a major disease affecting mainly calves, causing mortality both in ranch (8.5%) and pastoral (8.2%) herds. Meanwhile,
drought was a more serious in pastoral than ranch herds (p < 0.05), killing 28.5 % and 5.8% of adult female cattle in respective
production systems. Other endemic diseases found and controlled by vaccination were FMD, CBPP and blackquarter. In both cattle
and goats helminthosis was causing mortalities, 3.3% and 0.8% among calves in pastoral and ranches respectively; and 4.8%
and 6.9% among kids and sub-adult goats respectively. Many cases of abortions occurred among pastoral herds. In conclusion,
the disease incidence among livestock was the same or relatively low as compared to other areas without wildlife. 相似文献
92.
T. Reg Preston 《Tropical animal health and production》2009,41(7):1071-1080
Responding to the challenges posed by global warming, peak oil and biofuels will require a paradigm shift in the practice
of agriculture and in the role of live stock within the farming system. Farming systems should aim at maximizing plant biomass
production from locally available diversified resources, processing of the biomass on farm to provide food, feed and energy
and recycling of all waste materials. The approach that is the subject of this paper is that the generation of electricity
can be a by-product of food/feed production. The concept is the fractionation of biomass into inedible cell wall material
that can be converted to an inflammable gas by gasification, the gas in turn being the source of fuel for internal combustion
engines driving electrical generators. The cell contents and related structures such as tree leaves are used as human food
or animal feed. As well as providing food and feed the model is highly appropriate for decentralized small scale production
of electricity in rural areas. It also offers opportunities for sequestration of carbon in the form of biochar the solid residue
remaining after gasification of the biomass. 相似文献
93.
Oliveiro Caetano de Freitas Neto Sonia Luisa Silva Lages Adriano Oliveira Torres Carrasco Angelo Berchieri Junior 《Tropical animal health and production》2009,41(8):1607-1614
We analyzed ostriches from an equipped farm located in the Brazilian southeast region for the presence of Salmonella spp. This bacterium was investigated in 80 samples of ostrich droppings, 90 eggs, 30 samples of feed and 30 samples of droppings
from rodents. Additionally, at slaughter-house this bacterium was investigated in droppings, caecal content, spleen, liver
and carcasses from 90 slaughtered ostriches from the studied farm. Also, blood serum of those animals were harvested and submitted
to serum plate agglutination using commercial Salmonella Pullorum antigen. No Salmonella spp. was detected in any eggs, caecal content, liver, spleen, carcass and droppings from ostriches and rodents. However,
Salmonella Javiana and Salmonella enterica subsp. enterica 4, 12: i:- were isolated from some samples of feed. The serologic test was negative for all samples. Good sanitary farming
management and the application of HACCP principles and GMP during the slaughtering process could explain the absence of Salmonella spp. in the tested samples. 相似文献
94.
Marco Pietra Renato Giulio Zanoni Angelo Peli Barbara Brunetti Nikolina Linta Ombretta Capitani Giuseppe Spinella 《Irish veterinary journal》2015,69(1):12
Background
The authors report the first case of feline gastric actinomycosis associated with infection by Actinomyces hordeovulneris.Case presentation
A 4-year-old, neutered male, semi-feral European cat, with a 1 year history of chronic vomiting, was referred to the clinic. Abdominal ultrasound examination identified a hypoechoic focal transmural thickening with loss of normal wall layering and hyperechoic speckles at the gastric body. Initial gastroscopic examination showed a tumour-like gastric mass with an ulcerated depression at the level of the greater curvature. Histologic examination of endoscopic biopsy specimens was consistent with a severe lymphoplasmacytic gastritis. After 2 months, due to persistence of abdominal discomfort, surgical exploration and intraoperative sampling of gross abnormalities was recommended. Full thickness gastric wall biopsies, and fine needle aspiration of the gastric thickening and gastric lymph node, were performed. Histopathological examination identified a transmural pyogranulomatous gastritis. Aspirate samples of the gastric wall cultured positive, with colony morphology, biochemical testing and PCR of the 16 s rRNA gene compatible with Actinomyces hordeovulneris. After 4 months of treatment with cefovecin (8 mg/kg subcutaneously every 14 days), the vomiting completely resolved, as well as the ultrasonographic gastric alteration.Conclusion
This case report of feline gastric actinomycosis, caused by Actinomyces hordeovulneris, suggests that gastric bacterial infection should be considered in cases of focal gastric wall thickening associated with chronic vomiting in the cat, which may otherwise closely resemble neoplastic disease. Once a diagnosis of actinomycosis was obtained, a correct treatment with antibiotic therapy can resolve it.95.
Probiotics of Lactobacillus acidophilus, Saccharomyces cerevisiae, and Aspergillus niger and three commercial exogenous fibrolytic enzymes (EFE) were tested in vitro to select best source and optimum dose followed
by in vivo studies on male buffalo calves. Bacterial (P < 0.001) and protozoal population were increased significantly (P < 0.001) with probiotics and EFE. In vitro dry matter digestibility was more (P < 0.001) on L. acidophilus and then on S. cerevisiae. Dose required for L. acidophilus and S. cerevisiae probiotics was 1 × 109 and 3 × 109 cfu/flask, respectively. Cellulase and xylanase were effective at 4,000 and 12,500 IU/kg DM. In vitro cell wall digestibility
was increased (P < 0.001) when probiotics and EFE were used together. Best source and optimum dose of probiotics and EFE were fed to 18 male
buffalo calves with concentrate supplement (CS). Calves were randomly divided into three groups either without probiotics
and EFE (CG) or with probiotics (EG1) or probiotics combined with EFE (EG2) on wheat straw diet. Organic matter, neutral detergent fiber, and acid detergent fiber digestibility was improved significantly.
Average daily weight gain (ADG) and feed efficiency were significantly higher (P < 0.001) in EG2 than EG1 or CG. Final body weight was 4% and 12% and feed efficiency was 2.6% or 1.6% more (P < 0.001) in EG2 compared to CG or EG1, respectively. Fortification of CS with probiotics and EFE together had more impact on FE and ADG in buffalo calves. 相似文献
96.
97.
98.
A cross-sectional survey was conducted in Sudan to determine sero-prevalence and risk factors associated with Neospora caninum infection in non-vaccinated dairy herds and to assess importance of the disease. Blood samples were collected from a total
of 262 animals from 25 herds. Sera were tested for antibodies against N. caninum using ELISA test. The prevalence rates of N. caninum antibodies in cattle were high both at herd level (44%) and at individual animal level (10.7%). Herd level infection rates
were similar in Khartoum State (43.7%) and at Gazira States (44.4%). The overall prevalence rates were higher (16.1%) in Gazira
State than in Khartoum State (9%) but with no significant variation. The sero-prevalence at individual animal level was significantly
higher (p < 0.05) in animals with history of abortion (12.8%) than in apparently healthy animal (11.3%), animal with history of infertility
(8.1%), or neonatal death of calves (4.3%). In addition, significantly higher (P < 0.05) sero-prevalence was observed in samples collected during the rainy season (6.87%) than winter (3.05%) or summer (0.76%).
However, no significant differences in sero-prevalence due to locality, animal breed, sex, and age were observed (p > 0.05). This preliminary study reveals for the first time the existence of natural N. caninum infection in Sudan. Also, the findings of the present study indicated that this disease is highly prevalent in two major
areas of dairy production in the country, and this calls for control strategy to be implemented. 相似文献
99.
Megumi Yoshida Takashi Nakajima Takuji Tonooka 《Journal of General Plant Pathology》2008,74(5):355-363
In the western part of Japan, two wheat cultivars, Nishinokaori and Minaminokaori, are currently cultivated for breadmaking.
Breadmaking wheat requires a higher protein content compared to the Japanese noodle wheat (the major type of wheat in Japan).
This high protein level in the grain is obtained by top-dressing with nitrogen (N) near anthesis. Because such N applications
may increase levels of Fusarium head blight (FHB) and consequent mycotoxin [deoxynivalenol (DON) and nivalenol (NIV)] accumulation
in the grain, the effect of N application (0, 4, and 8 g/m2) at anthesis on FHB and mycotoxin accumulation in Nishinokaori and Minaminokaori was tested in the greenhouse in 2004 and
2005 and in two fields in 2006. In the greenhouse, plants were spray inoculated at 3, 10, and 20 days after N treatment. In
field experiments, colonized maize kernels, which generate ascospores during the testing season, served as inoculum. In all
experiments for both cultivars, N application at anthesis significantly increased grain protein as expected, but had no significant
effect on FHB and DON and NIV levels in grain. These results suggest that, at least in these cultivars, N can be applied close
to anthesis without increasing the risk of FHB and mycotoxin (DON and NIV) accumulation. 相似文献
100.
Michael P. Ward Courtney A. Wittich Geoffrey Fosgate Raghavan Srinivasan 《Veterinary research communications》2009,33(5):461-471
West Nile Virus (WNV) was first detected in the Texas equine population during June 2002. Infection has since spread rapidly
across the state and become endemic in the equine population. Environmental risk factors associated with equine WNV attack
rates in Texas counties during the period 2002 to 2004 were investigated. Equine WNV attack rates were smoothed using an empirical
Bayesian model, because of the variability among county equine populations (range 46−9,517). Risk factors investigated included
hydrological features (lakes, rivers, swamps, canals and river basins), land cover (tree, mosaic, shrub, herbaceous, cultivated
and artificial), elevation, climate (rainfall and temperature), and reports of WNV-positive mosquito and wild bird samples.
Estimated county equine WNV attack rate was best described by the number of lakes, presence of broadleaf deciduous forest,
presence of cultivated areas, location within the Brazos River watershed, WNV-positive mosquito status and average temperature.
An understanding of environmental factors that increase equine WNV disease risk can be used to design and target disease control
programs. 相似文献