全文获取类型
收费全文 | 1039篇 |
免费 | 47篇 |
专业分类
林业 | 98篇 |
农学 | 9篇 |
基础科学 | 7篇 |
126篇 | |
综合类 | 176篇 |
农作物 | 22篇 |
水产渔业 | 43篇 |
畜牧兽医 | 525篇 |
园艺 | 24篇 |
植物保护 | 56篇 |
出版年
2021年 | 10篇 |
2020年 | 21篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 19篇 |
2013年 | 47篇 |
2012年 | 28篇 |
2011年 | 52篇 |
2010年 | 32篇 |
2009年 | 24篇 |
2008年 | 55篇 |
2007年 | 29篇 |
2006年 | 38篇 |
2005年 | 26篇 |
2004年 | 33篇 |
2003年 | 49篇 |
2002年 | 35篇 |
2001年 | 21篇 |
2000年 | 21篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 25篇 |
1991年 | 28篇 |
1990年 | 22篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1986年 | 20篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1976年 | 6篇 |
1974年 | 12篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1971年 | 8篇 |
1970年 | 13篇 |
1968年 | 12篇 |
1967年 | 7篇 |
1966年 | 7篇 |
排序方式: 共有1086条查询结果,搜索用时 31 毫秒
1.
Experiments were conducted to determine comparative populations of Salmonella typhimurium in the most commonly infected body organs of long-term carrier swine. Naturally farrowed Salmonella-free pigs (n = 58) were orally exposed to S typhimurium when they were 47 days old. Necropsy of 3 to 5 randomly selected pigs was conducted at 3, 7, 10, 14, and 17 days and at 3, 4, 5, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. Mean populations (log10/g) of S typhimurium in palatine tonsils, ileum, cecum (wall and contents), ascending colon (wall and contents), and mandibular and ileocolic lymph nodes were estimated at each necropsy, using a most-probable-number method of bacteriologic examination. Populations of organisms in cecum and colon were similar to each other throughout the duration of the study. Mean populations (log10/g) associated with cecal and colonic walls decreased from 6.1 and 6.6, respectively, during the first postexposure (PE) week to less than or equal to 1.67 from PE weeks 4 to 28. Populations (log10/g) associated with cecal and colonic contents decreased from 5.6 and 5.5, respectively, at PE day 3 to 2.5 and 2.7, respectively, at PE week 4, and remained less than or equal to 2.8 until week 28. Populations (log10/g) associated with intestinal walls and contents were closely correlated during the study. Population (log10/g) in the ileum was greater than or equal to 5.3 from PE days 3 to 17, then varied between 5.4 and -0.4 up to PE week 28.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
2.
3.
Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs. 相似文献
4.
5.
Bisset SA Vlassoff A McMurtry LW Elliott DC Cobb RM Kieran PJ Wood IB 《New Zealand veterinary journal》1992,40(3):97-100
The efficacy of an oral formulation of the newly developed parasiticide, moxidectin, was tested against benzimidazole-resistant Haemonchus contortus, Trichostrongylus colubriformis, and Nematodirus spathiger, levamisole-resistant Ostertagia circumcincta, and susceptible Cooperia curticei infections in weaned lambs. Thirty-two lambs were experimentally infected with mixed doses of the above strains of nematodes. They were allocated into four treatment groups by stratified randomisation using liveweights and faecal egg counts 28 days later. One group received moxidectin at 0.2 mg/kg liveweight, one group oxfendazole at 4.5 mg/kg liveweight, one group levamisole at 7.5 mg/kg liveweight and the last group remained untreated as the control. Worm burdens in the lambs at slaughter 10 days after oral treatment confirmed the resistance status of the nematode strains used, and showed that moxidectin had a greater than 99.9% efficacy (p<0.01) against all of them. No adverse effects due to treatment with moxidectin were observed in any of the animals. 相似文献
6.
7.
8.
The grey squirrel is recognised as a pest species of economic importance but the justification of the view appears to be founded on local areas of severe damage. Despite evidence that damage may not be alleviated by squirrel population destruction, Warfarin poisoning was introduced as an alternative to trapping.The utilisation by wildlife of a poison hopper designed for grey squirrel control was investigated by automatic photography. Results confirmed that a number of species may feed from the grain presented via the hopper. However, the majority of the bait was removed during the hours of darkness when grey squirrels were not active. It is a conservative estimate that between 55 and 65% of the grain entered the environment via animals other than squirrels.In addition, the removalof bait by night visitors resulted in the accumulation of large quantities of bait at and around the entrance to the hopper tunnel. This increased accessibility to the potentially poisoned bait by animals other than squirrels.Until such time as evidence is produced to show these results as exceptional, it can only be concluded that fears expressed over the lack of specificity of this method of control are justified. 相似文献
9.
Wood RE 《Science (New York, N.Y.)》1952,116(3014):358-359
10.