全文获取类型
收费全文 | 962篇 |
免费 | 59篇 |
国内免费 | 19篇 |
专业分类
林业 | 46篇 |
农学 | 25篇 |
基础科学 | 10篇 |
73篇 | |
综合类 | 302篇 |
农作物 | 36篇 |
水产渔业 | 49篇 |
畜牧兽医 | 428篇 |
园艺 | 33篇 |
植物保护 | 38篇 |
出版年
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 14篇 |
2019年 | 24篇 |
2018年 | 14篇 |
2017年 | 26篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 29篇 |
2013年 | 41篇 |
2012年 | 51篇 |
2011年 | 52篇 |
2010年 | 44篇 |
2009年 | 48篇 |
2008年 | 49篇 |
2007年 | 49篇 |
2006年 | 34篇 |
2005年 | 36篇 |
2004年 | 45篇 |
2003年 | 13篇 |
2002年 | 22篇 |
2001年 | 27篇 |
2000年 | 21篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1992年 | 16篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 6篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1974年 | 12篇 |
1973年 | 11篇 |
1972年 | 5篇 |
1971年 | 6篇 |
1970年 | 6篇 |
1910年 | 4篇 |
排序方式: 共有1040条查询结果,搜索用时 46 毫秒
31.
32.
33.
试验设21个日粮组, 蛋白质、脂肪、碳水化合物梯度变化范围分别在33% ~ 51%、3% ~ 18%、23% ~ 32%。在水温( 25. 25 ? 1. 91) e 条件下, 在水泥池中对平均体重为( 2. 01 ? 0. 04) g的360尾齐口裂腹鱼进行了60 d的生长试验, 研究日粮中蛋白质、脂肪和碳水化合物对齐口裂腹鱼生长、体组成和肝脏组织的影响。结果表明: 各组鱼特定生长率随着日粮蛋白质水平的增加而增加; 体蛋白含量不受日粮组成的影响, 体脂肪随着日粮脂肪水平的增加而增加, 体碳水化合物受日粮碳水化合物的影响极显著, 而不受日粮蛋白质和脂肪的影响。齐口裂腹鱼幼鱼能耐忍23% ~ 26%的碳水化合物水平, 且能利用6% ~ 12%的日粮脂肪。基于齐口裂腹鱼幼鱼对日粮碳水化合物和脂肪含量需求分别为23% ~ 26%和6% ~ 12%时, 蛋白质需求量为42% ~ 48%, 能蛋比为41. 3 kJ/g。 相似文献
34.
35.
J J Ettlinger T Ford J E Palmer 《Journal of the American Veterinary Medical Association》1990,196(10):1628-1630
Proximal enteritis was diagnosed on the basis of clinical signs of disease in 2 Standard-bred yearlings from the same farm. Large volumes of fluid were repeatedly obtained during gastric decompression. The horses did not respond to treatment with IV administered fluids, antimicrobial agents, cimetidine, and metoclopramide. Postmortem findings confirmed severe focal chronic active duodenitis with stricture formation. An etiologic agent was not identified. 相似文献
36.
AIM:To elucidate the molecular mechanisms of lipoic acid (LA) on redox regulation and digestive function in intestine of C57BL/6 mice fed high fat diet (HFD).METHODS:C57BL/6 mice were randomly assigned to one of three groups (n=8).The control group consumed an ordinary diet.The other two experimental groups were fed with a high fat diet, high fat plus 0.1% LA.After 6 weeks, the activities of digestive enzymes were examined.In order to evaluate the antioxidant status of the mice, superoxide dismutase (SOD), malondialdehyde (MDA), total antioxidant capacity (TAC) and reactive oxygen species (ROS) in intestinal homogenate were measured.To investigate the molecular mechanisms underlying the effects of LA, the gene expression profiles in intestine were examined using the GeneChip microarray system.RESULTS:A depressed antioxidant defense system, accompanied by digestive and absorptive function impairment, was observed in HFD-fed mice.These changes were partially restored in the LA-treated group.DNA microarray analysis of intestine showed that LA ingestion up-regulated the expression of genes related to free-radical scavenger enzymes, digestive enzymes and transporters.CONCLUSION:Treatment with LA improves redox homeostasis and the function of intestine in mice fed HFD.The mechanism may involve preventing oxidative stress by scavenging ROS directly and increasing those of free-radical scavenger enzymes gene expression indirectly. 相似文献
37.
B J Weigler D W Hird W M Sischo J C Holmes C Danaye-Elmi C W Palmer W W Utterback 《Journal of the American Veterinary Medical Association》1990,196(12):1945-1949
Twenty-nine California dairy herds were studied over a 12-month period from 1988 to 1989 as part of the National Animal Health Monitoring System. Monthly interviews administered to dairy producers were used to measure the costs of all health-related expenditures and disease incidence in these herds. Of the total $1,523,558 reported, $1,355,467 (89%) was attributed to cost of disease events and $168,091 (11%) to cost of disease prevention. Most (78%) of the cost of disease events was attributable to death and culling losses. Veterinary services accounted for only $54,099 (4%) of total costs, 64% of which was used for disease prevention, compared with 36% for disease treatment. Udder disease was the most costly category of diseases reported at an average of $49.85/head at risk annually, followed by reproductive problems at $38.05. Through the use of sampling strategies less biased than those used in other surveys, the National Animal Health Monitoring System is designed to provide statistically-valid estimates of disease incidence and costs across broad geographic areas, potentially benefiting all those interested in the economics of livestock diseases in the United States. 相似文献
38.
39.
G. LE TRAON S. BURGAUD & L. J. I. HORSPOOL 《Journal of veterinary pharmacology and therapeutics》2009,32(3):213-218
Long-term oral treatment with cimetidine is recommended to reduce vomiting in dogs with chronic gastritis. Despite this, few studies have specifically examined the plasma disposition and pharmacokinetics of cimetidine in dogs, particularly following repeated oral administration. The pharmacokinetics of cimetidine following oral administration as tablets was investigated in healthy dogs. Cimetidine was absorbed rapidly post-treatment ( t max = 0.5 h). A mean absolute bioavailability of 75% was calculated following a single oral administration of 5 mg cimetidine/kg body weight. After intravenous administration, a plasma half-life of 1.6 h was calculated. Repeated oral administration at the recommended dose rate and regime (5 mg/kg body weight three times daily) for 30 consecutive days did not lead to any accumulation of cimetidine in plasma. Food intake concomitant with oral administration of cimetidine delayed ( t max = 2.25 h) and decreased the rate and extent of absorption ( AUC ) by about 40%. Cimetidine was well absorbed in fasted dogs. Administration of food decreased the bioavailability of cimetidine by 40%. Cimetidine does not accumulate over time in plasma when administered long term to dogs. 相似文献
40.
R D Jolly R D Martinus A Shimada I M Fearnley D N Palmer 《Canadian journal of veterinary research》1990,54(1):15-21
The pathogenesis of the ceroid-lipofuscinoses, inherited storage diseases of children, was studied in an ovine model. This was shown to have clinical and pathological features most in common with the late infantile and juvenile human forms of the disease. The ability to study sequential changes allowed the retinal lesions to be described as a dystrophy of photoreceptor outer segments which preceded loss of the photoreceptor cells. An early decrease in amplitude of the c-wave electroretinograph was attributed to a decrease in the transpigment epithelial component. The decreased a- and b-wave amplitudes were attributed to the changes in and loss of, photoreceptor cells. The chemical components of isolated storage cytosomes were analyzed and shown to consist mostly of protein. Sequence analysis of the dominantly stored protein showed that it was identical to the DCCD reactive proteolipid or subunit c of mitochondrial adenosine triphosphate synthase and that it comprised approximately 50% of storage material. Based on the adage that the dominantly stored species should reflect the underlying biochemical anomaly, it was concluded that it was of pathogenic significance. This highly hydrophobic protein tends to extract with lipids in chloroform/methanol and is thus known as a proteolipid. Some of the remainder of the stored proteins also had this characteristic. It was concluded that ovine ceroid-lipofuscinosis was a proteinosis, more specifically a proteolipid proteinosis and as such it forms the prototype of a new class of storage diseases. Recognition of the nature of the dominantly stored chemical species has helped understanding of a variety of chemical and physical characteristics attributed to the whole pigment.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献