全文获取类型
收费全文 | 38775篇 |
免费 | 2274篇 |
国内免费 | 285篇 |
专业分类
林业 | 1597篇 |
农学 | 1437篇 |
基础科学 | 324篇 |
5530篇 | |
综合类 | 5715篇 |
农作物 | 1508篇 |
水产渔业 | 1851篇 |
畜牧兽医 | 20211篇 |
园艺 | 467篇 |
植物保护 | 2694篇 |
出版年
2021年 | 372篇 |
2020年 | 431篇 |
2019年 | 481篇 |
2018年 | 792篇 |
2017年 | 846篇 |
2016年 | 756篇 |
2015年 | 636篇 |
2014年 | 792篇 |
2013年 | 1859篇 |
2012年 | 1329篇 |
2011年 | 1549篇 |
2010年 | 1073篇 |
2009年 | 1103篇 |
2008年 | 1492篇 |
2007年 | 1342篇 |
2006年 | 1276篇 |
2005年 | 1108篇 |
2004年 | 1054篇 |
2003年 | 1051篇 |
2002年 | 939篇 |
2001年 | 1262篇 |
2000年 | 1241篇 |
1999年 | 941篇 |
1998年 | 393篇 |
1997年 | 424篇 |
1996年 | 345篇 |
1995年 | 393篇 |
1994年 | 345篇 |
1992年 | 665篇 |
1991年 | 793篇 |
1990年 | 691篇 |
1989年 | 728篇 |
1988年 | 667篇 |
1987年 | 638篇 |
1986年 | 676篇 |
1985年 | 602篇 |
1984年 | 468篇 |
1983年 | 418篇 |
1979年 | 566篇 |
1978年 | 441篇 |
1977年 | 362篇 |
1976年 | 365篇 |
1975年 | 402篇 |
1974年 | 464篇 |
1973年 | 481篇 |
1972年 | 453篇 |
1970年 | 372篇 |
1969年 | 407篇 |
1968年 | 358篇 |
1967年 | 363篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The relationship between liver fat content and haematology was investigated in 369 cows from eight herds sampled in the second week after calving. High levels of fat in the liver were associated with a depression in total white cell count and in neutrophils, eosinophils and lymphocytes. There was no correlation between liver fat content and the percentage of E rosetting lymphocytes, packed cell volume or haemoglobin concentration. The changes in peripheral white cell counts may be related to the increased incidence of post parturient disease in cows with fatty liver. 相似文献
992.
An outbreak of fibropapillomatosis following rectal examination for pregnancy and involving the anus and to a lesser extent the rectum in a herd of beef heifers in western Victoria is described. Almost half the herd were involved at one time; most lesions regressed with the following 16 weeks. Lesions varied from 0.2 mm diameter polyps up to large multiple lesions up to 7 x 5 x 2 cm with a broad base. The presence of lesions did not affect the body condition or health of the animals. 相似文献
993.
Albendazole administered to cattle at doses of 45, 35, 25, and 15 mg/kg of body weight reduced the number of viable Fasciola hepatica adults by 99.8%, 97.6%, 97.6%, and 95.7%, F hepatica immatures by 100%, 98.6%, 98.6% and 91.9% and Fascioloides magna by 96.5%, 99.1%, 94.0%, and 94.0%, respectively. Statistical evaluation by one-way analysis of variance, showed significant (P less than 0.05) differences in burdens of each fluke species between treated and untreated cattle, but differences in efficacy between any two of the four drug doses were not significant. Signs of toxicosis were not observed between the time of drug administration and slaughter 7 to 10 days later. 相似文献
994.
Sulfamethazine residues in uncooked edible tissues of port following recommended oral administration and withdrawal. 总被引:1,自引:0,他引:1 下载免费PDF全文
Commercial feed rations containing sulfamethazine at the level of 110 ppm were fed for a period of 65 days to market pigs in a study simulating normal farm practices. The levels of sulfamethazine at the end of medication were in excess of 10 ppm in liver and kidney and up to 2.6 ppm in muscle tissues. Concentrations of sulfamethazine in tissues from pigs after withdrawal of medicated feed depleted to 0.1 ppm within nine days. The rate of depletion was similar for all tissues. It was observed that storage of tissue samples at freezer temperature (-20 degrees C) for 30 days further reduces sulfamethazine levels by 3 to 20% of their original value. 相似文献
995.
Applications of GA3 in May/June, when the first flush of growth was maturing, induced an extra flush of vegetative growth and initiated lateral bud break. Flower initiation was delayed and flower size reduced by the GA3. These responses were only slightly modified by additional sprays with BAP and TIBA. GA4+7 was ineffective in promoting either extra extension growth or lateral bud break, but it did reduce flower size. 相似文献
996.
997.
Benlate (50 per cent wettable powder), the commercial formulation of the systemic fungicide benomyl, was applied to a flooded alluvial soil at concentrations of 5 to 100 μg/g active ingredient. At about the field application rate (S μg/g), benomyl retarded the decrease in the redox potentials of the flooded soil and curtailed the accumulation of iron and manganese in solution, both without and with added rice straw (0.5 per cent). 相似文献
998.
999.
1000.