全文获取类型
收费全文 | 11520篇 |
免费 | 831篇 |
国内免费 | 111篇 |
专业分类
林业 | 1092篇 |
农学 | 484篇 |
基础科学 | 96篇 |
2979篇 | |
综合类 | 486篇 |
农作物 | 617篇 |
水产渔业 | 1244篇 |
畜牧兽医 | 4227篇 |
园艺 | 205篇 |
植物保护 | 1032篇 |
出版年
2023年 | 89篇 |
2022年 | 144篇 |
2021年 | 297篇 |
2020年 | 315篇 |
2019年 | 297篇 |
2018年 | 531篇 |
2017年 | 542篇 |
2016年 | 547篇 |
2015年 | 422篇 |
2014年 | 480篇 |
2013年 | 744篇 |
2012年 | 923篇 |
2011年 | 858篇 |
2010年 | 545篇 |
2009年 | 451篇 |
2008年 | 636篇 |
2007年 | 643篇 |
2006年 | 532篇 |
2005年 | 518篇 |
2004年 | 439篇 |
2003年 | 401篇 |
2002年 | 319篇 |
2001年 | 231篇 |
2000年 | 239篇 |
1999年 | 203篇 |
1998年 | 52篇 |
1997年 | 56篇 |
1996年 | 36篇 |
1995年 | 37篇 |
1994年 | 23篇 |
1993年 | 22篇 |
1992年 | 60篇 |
1991年 | 45篇 |
1990年 | 51篇 |
1989年 | 53篇 |
1988年 | 42篇 |
1987年 | 42篇 |
1986年 | 48篇 |
1985年 | 53篇 |
1984年 | 40篇 |
1983年 | 37篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1979年 | 34篇 |
1978年 | 32篇 |
1977年 | 30篇 |
1974年 | 30篇 |
1973年 | 45篇 |
1972年 | 33篇 |
1971年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
M R Hidalgo Argüello N Díez-Ba?os B Martínez-González F A Rojo-Vázquez 《Veterinary parasitology》2001,102(1-2):143-150
Thirty ewes naturally infected with Sarcoptes scabiei var. ovis, were allocated into three groups of 10 animals each. Animals in groups B and C were treated on day 0 and on days 0 and +10, respectively, with moxidectin 1% injectable at a dose of 0.2mg moxidectin/kg body weight (BW). Group A remained untreated. Seven days before treatment, the geometric mean of Sarcoptes scabiei var. ovis per square centimeter of skin in groups A, B and C were not significantly different. From the day of treatment to the end of the trial, the average number of mites/cm(2) increased in untreated animals and decreased in groups B and C, but these values were higher for group C. Active lesions produced by S. scabiei var. ovis consistently increased during the trial in the untreated animals; in group B the minimum count occurred on day +56 this reduction being more evident in group C (no lesions on days +49 and +56). Also in this group, the number of cured animals was 100%, therefore, the application of two treatments with moxidectin (group C) showed higher efficacy than a single treatment (group B). Body condition score decreased in the three experimental groups along the trial. All animals were individually weighed on days -1, +28 and at the end of the trial. No adverse reactions were observed in the animals treated with 0.2mg moxidectin/kg BW. 相似文献
995.
J Gilka V Gajd?sková M Malíková J Masek H Docekalová R Hais A Láníková M Pavlasová 《Veterinární medicína》1987,32(12):721-730
The residues of antimicrobial substances, some chlorinated and organophosphate pesticides and chemical elements were studied in the meat and organs of a group of bulls fed food-waste paste for 240 days and a group of bulls fed the same paste with an addition of poultry waste. These residues were also studied in the tissues of pigs fed the food-waste paste for 135 and 151 days until slaughter. The feed ingredients were also examined during the feeding trials. Although some of the residues under study were found in the tissues of the test animals at increased amounts, their concentrations were diluted in the tissues in the majority of cases when the feed pastes were administered. All residue contents recorded in the tissues remained below the permissible limits as given in valid instructions and directives so that the products, i. e. meat and organs, could be deemed digestible on the basis of hygienic evaluation. Hence, from the point of view of the occurrence of residues of foreign substances in edible tissues, the administration of food-waste pastes to farm animals can be considered as admissible. 相似文献
996.
997.
The activity of alkaline phosphatase (EC 3.1.3.1.) was studied in the small intestines of piglets infected with the coccidia Isospora suis on the first and fifth day of age. Alkaline phosphatase activity is reduced significantly the third to fourth day after infection (DAI) throughout the small intestine in piglets infected on the fifth day of age. Similar results were obtained in the piglets killed the eighth to tenth DAI which had also been infected on the fifth day of their age. Piglets infected the first day of age and killed on the 8th to 13th DAI exhibited no larger differences from the above-mentioned groups, but alkaline phosphatase activity was distributed more regularly all over the surface of the villi. The normal values, comparable with the controls, were not obtained within 13 days after infection (piglet age 14 days). 相似文献
998.
Out of 189 lambs in the flock, 25 animals suffered from bilateral or unilateral conjunctivitis, or keratoconjunctivitis. By serological examination (RVK), positive levels of antibodies to the group-specific antigen of Chl. psittaci were found in three out of six lambs examined by laboratory methods. Bacteriological examination of eye smears of six lambs showed in four cases the infection by microorganisms of Moraxella bovis. Smears from the conjunctivas of these lambs were after preparation instilled in the yolk sacs of six to seven days old chicken embryos. One strain of Chlamydia psittaci was isolated from the same material as Moraxella bovis. 相似文献
999.
The determination of zearalenone content in cereals (maize, wheat and barley) was performed by means of liquid chromatography using the Czechoslovak-made apparatus. This method enables to determine this mycotoxin up to the concentration of 8 micrograms per 1 kg of grain with the accuracy exceeding +/- 9%. 相似文献
1000.
In two experiments the effect of feeding dried crushed white and red grape press cake replacing 10--20% of the complex feed mixture A1 and SOL, was studied on the 21 biochemical indicators of blood serum, plasma, suprarenal glands, liver and tissue of fattened pigs. Changes indicating unsuitability of this non-traditional feed were not observed. During feeding red grape press cake, the young pigs of 35kg body weight had a lower concentration of glucose in blood serum, in comparison with the control. The temporary increase of calcium level and decrease of inorganic phosphorus in these animals was accompanied by a lower activity of alkaline phosphatase. White and red grape press cake affected positively the vitamin E level in blood serum. In the muscles of the experimental slaughter pigs protein proportion was increased and fat proportion was decreased. 相似文献