全文获取类型
收费全文 | 663篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
林业 | 48篇 |
农学 | 17篇 |
基础科学 | 10篇 |
129篇 | |
综合类 | 103篇 |
农作物 | 24篇 |
水产渔业 | 83篇 |
畜牧兽医 | 217篇 |
园艺 | 21篇 |
植物保护 | 45篇 |
出版年
2021年 | 10篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 36篇 |
2012年 | 37篇 |
2011年 | 28篇 |
2010年 | 17篇 |
2009年 | 26篇 |
2008年 | 39篇 |
2007年 | 29篇 |
2006年 | 33篇 |
2005年 | 39篇 |
2004年 | 21篇 |
2003年 | 28篇 |
2002年 | 35篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 8篇 |
1967年 | 5篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1930年 | 5篇 |
排序方式: 共有697条查询结果,搜索用时 31 毫秒
91.
92.
93.
Jergens AE 《Journal of Feline Medicine and Surgery》2012,14(7):445-458
PRACTICAL RELEVANCE: Feline idiopathic inflammatory bowel disease (IBD) denotes one form of chronic enteropathy that is immunologically mediated and characterized by persistent or recurrent gastrointestinal (GI) signs and histologic inflammation. Signs of vomiting, diarrhea and weight loss generally predominate, and mucosal inflammation may occur in any portion of the GI tract (especially the small intestine). Affected cats may also have concurrent inflammation in other organs, such as the pancreas and liver, which may impact clinical disease severity. CLINICAL CHALLENGES: The exact etiologies of this heterogeneous group of disorders have yet to be determined, though results from basic science and clinical studies suggest that interplay between genetic factors and enteric bacteria is crucial for disease development. The diagnosis is one of exclusion and requires intestinal mucosal biopsy to characterize the type and severity of the inflammatory infiltrate, and to differentiate IBD from other disorders, including alimentary lymphoma. Controversy exists concerning the relative diagnostic accuracy of endoscopic versus full-thickness specimens for the diagnosis of IBD and its differentiation from alimentary lymphoma. AUDIENCE: This article is intended to provide veterinary practitioners with a comprehensive clinical update on idiopathic IBD in cats. It reviews the current evidence-based data, the diagnostic approach, the evolving histologic criteria, and treatment options and outcome for feline patients with this syndrome. 相似文献
94.
Anna Haug Rune R⊘dbotten Liv Torunn Mydland Olav Albert Christophersen 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(2):71-77
Abstract A feeding experiment involving histidine supplementation to broiler feed resulted in increased concentration of the histidine containing dipeptides anserine and carnosine in broiler breast muscle. Supplementation with 1 g histidine per kg feed gave a 64% increase in carnosine, and about 10% increase in anserine in the muscle. The standard broiler feed concentrate now in use in Norway seems to contain less histidine than what may be needed for optimal synthesis of carnosine and anserine. These dipeptides have important roles as antioxidants, pH buffering agents and anti-glycation agents. They may have important roles in meat for increasing its stability, shelf life and antioxidant capacity, and it might be speculated that broiler meat rich in anserine and carnosine in the future will be considered a type of functional food, having possible health-beneficial effects. Histidine supplementation of standard Norwegian broiler feed concentrate should be considered. 相似文献
95.
Kouassi N’Guessan Louis Berenger Yao Koffi Marcellin Sangare Naminata Trokourey Albert Metongo Bernard Soro 《Journal of Soils and Sediments》2019,19(2):929-944
Journal of Soils and Sediments - Trace metals accumulate in the food web and can pose high risks to human health and aquatic biota. We investigated seasonal and spatial variations of Cu, Zn, Pb,... 相似文献
96.
Suchodolski JS Morris EK Allenspach K Jergens AE Harmoinen JA Westermarck E Steiner JM 《Veterinary microbiology》2008,132(3-4):379-388
Limited information is available about the prevalence and phylogenetic classification of fungal organisms in the gastrointestinal tract of dogs. Also, the impact of fungal organisms on gastrointestinal health and disease is not well understood. The aim of this study was to evaluate the prevalence of fungal DNA in the small intestine of healthy dogs and dogs with chronic enteropathies. Small intestinal content was analyzed from 64 healthy and 71 diseased dogs from five different geographic locations in Europe and the USA. Fungal DNA was amplified with panfungal primers targeting the internal transcriber spacer (ITS) region. PCR amplicons were subjected to phylogenetic analysis. Fungal DNA was detected in 60.9% of healthy dogs and in 76.1% of dogs with chronic enteropathies. This prevalence was not significantly different between the two groups (p=0.065). Fungal DNA was significantly more prevalent in mucosal brush samples (82.8%) than in luminal samples (42.9%; p=0.002). Sequencing results revealed a total of 51 different phylotypes. All sequences belonged to two phyla and were classified as either Ascomycota (32 phylotypes) or Basidiomycota (19 phylotypes). Three major classes were identified: Saccharomycetes, Dothideomycetes, and Hymenomycetes. The most commonly observed sequences were classified as Pichia spp., Cryptococcus spp., Candida spp., and Trichosporon spp. Species believed to be clinically more important were more commonly observed in diseased dogs. These results indicate a high prevalence and diversity of fungal DNA in the small intestine of both healthy dogs and dogs with chronic enteropathies. The canine gastrointestinal tract of diseased dogs may harbor opportunistic fungal pathogens. 相似文献
97.
98.
99.
Bjorn Roth Albert Imsland Lars Helge Stien Rian Schelvis-Smit Snorri Gunnarsson Atle Foss 《Aquaculture International》2010,18(3):461-474
In order to test seasonal, rearing, maturing and anaerobic muscle activity effect on the flesh quality of turbot (Scophthalmus maximus) a total of 80 farmed turbot from three different strains from reared under natural or continuous light were killed by a
percussive blow to the head in November (winter, Icelandic strain), March (spring, Portuguese strain) and June (summer, domesticated
strain (France turbot)). To test the effect of anaerobic muscle activity, 10 fish were on each occasion pre rigor filleted, where one fillet was used as a control, while the other fillet was electrically stimulated using a squared 5 Hz,
10 V pulsed DC for 3 min. All pre rigor fillets were measured for pH, weighed, wrapped in aluminum foil and stored in polystyrene boxes with ice. After 7 days of
storage the fillets were measured instrumentally for pH, drip loss, colour (CIE L* a* b*) and texture properties such as hardness and shear force, while fillet shrinkage and colour (RBG) were evaluated with computer
imaging on photographs from a standard lightbox. Results showed that softness of the flesh was mainly influenced by factors
associated with growth, such as season, photoperiod and maturation. Anaerobic muscle activity simulated with electrical stimulation
caused an increase in drip loss (<1%) and loss of shear force (<4%), but had no effect on hardness or fillet shrinkage. Computer
imaging revealed that muscle contractions related to the electrical stimulus forced out blood from the fillet causing less
reddishness for the entire storage period. We conclude that a pH drop upon slaughter associated with anaerobic muscle activity
has a minor effect on the flesh quality in the short run, while seasonal/alternatively genetic effects are predominant. 相似文献
100.
Albert K. Imsland Snorri Gunnarsson A. Foss Benedikt Sigur?sson Sindri Sigur?sson 《Journal of the World Aquaculture Society》2009,40(6):762-770
We compared growth properties of spotted wolffish with initial mean weight (± SE) 3.65 (± 0.15) kg reared in shallow raceways at three different densities (50, 70, and 90 kg/m2, corresponding to approx. 170, 240, and 310 kg/m3) in a 447‐day‐long growth trial at ambient temperature (mean (± SD), 4.2 C ± 1.9). Growth in all three groups was comparable, but there was a trend toward higher growth at the highest density. Final mean weights (kg ± SE) were 4.90 (± 0.15), 4.80 (± 0.16), and 5.05 (± 0.11), at the 50, 70, and 90 kg/m2 density, respectively. Initially, growth rates were higher at the 90 kg/m2 density group compared to the two other densities, but overall growth rates were similar in all three groups. Feed conversion efficiency differed and was higher at the two highest densities compared to lowest density. The acid–base balance was influenced by the density treatment as there was a general trend toward higher partial pressure of CO2 and HCO in the 90 kg/m2 group. Calculated productivity increased almost linearly with increasing stocking density and was found to be 24, 42, and 66 g/m2/day at 50, 70, and 90 kg/m2, respectively. The results show that the optimum density conditions for farming large spotted wolffish, both with respect to growth rate, feed conversion, and productivity are at densities equal to or higher than 90 kg/m2. 相似文献