全文获取类型
| 收费全文 | 1309篇 |
| 免费 | 39篇 |
| 国内免费 | 3篇 |
专业分类
| 林业 | 484篇 |
| 农学 | 15篇 |
| 基础科学 | 1篇 |
| 140篇 | |
| 综合类 | 72篇 |
| 农作物 | 47篇 |
| 水产渔业 | 37篇 |
| 畜牧兽医 | 467篇 |
| 园艺 | 23篇 |
| 植物保护 | 65篇 |
出版年
| 2018年 | 23篇 |
| 2017年 | 18篇 |
| 2016年 | 28篇 |
| 2015年 | 11篇 |
| 2014年 | 17篇 |
| 2013年 | 29篇 |
| 2012年 | 44篇 |
| 2011年 | 28篇 |
| 2010年 | 16篇 |
| 2009年 | 19篇 |
| 2008年 | 39篇 |
| 2007年 | 31篇 |
| 2006年 | 35篇 |
| 2005年 | 43篇 |
| 2004年 | 27篇 |
| 2003年 | 21篇 |
| 2002年 | 22篇 |
| 2001年 | 26篇 |
| 2000年 | 24篇 |
| 1999年 | 16篇 |
| 1992年 | 18篇 |
| 1991年 | 15篇 |
| 1990年 | 24篇 |
| 1989年 | 20篇 |
| 1988年 | 15篇 |
| 1986年 | 18篇 |
| 1985年 | 22篇 |
| 1984年 | 24篇 |
| 1983年 | 21篇 |
| 1982年 | 20篇 |
| 1981年 | 19篇 |
| 1980年 | 15篇 |
| 1979年 | 23篇 |
| 1978年 | 25篇 |
| 1976年 | 13篇 |
| 1975年 | 11篇 |
| 1974年 | 15篇 |
| 1973年 | 24篇 |
| 1972年 | 11篇 |
| 1971年 | 20篇 |
| 1970年 | 20篇 |
| 1969年 | 14篇 |
| 1968年 | 11篇 |
| 1965年 | 12篇 |
| 1956年 | 13篇 |
| 1938年 | 11篇 |
| 1937年 | 13篇 |
| 1936年 | 11篇 |
| 1930年 | 12篇 |
| 1921年 | 13篇 |
排序方式： 共有1351条查询结果，搜索用时 171 毫秒
71.
Eleven cows in late lactation were exposed to butyric acid for three weeks and were compared to five controls. Two intraruminal doses were daily applied, that is 1.0 g/kg B.W. of butyric acid to six animals and 1.0 g/kg B.W. of sodium butyrate to another five. Decline in milk yield was clinically recorded in response to butyric acid, while muscle tremor and diarrhoea resulted additionally from sodium butyrate. Behaviours of the clinico-chemical parameters of beta-OH-butyrate, glucose, free fatty acids, bilirubin, ASAT, gamma-GT, AP, and cholesterol were comparable to those in fattening bulls. Liver damage was not safely established. Some of the clinico-chemical alterations were more strongly pronounced after administration of sodium butyrate. One cow fell ill with ketosis under butyric acid load. 相似文献
72.
73.
Heinrich Wilhelm Weber 《Forstwissenschaftliches Centralblatt》1922,44(6):214-224
Ohne Zusammenfassung 相似文献
74.
75.
76.
77.
In 9 experiments the vitamin A content of the livers of 64 newborn (still births and deaths up to 48 h p.p.) and 69 weaned piglets, 122 growers and 110 fattening pigs was investigated after slaughtering or autopsy. Liver samples were taken from 78 growers by means of biopsy after latarotomy. A fluorometric analysis of the plasma vitamin A level was made. At the time of birth the vitamin A content of the piglet livers was less than 100 IU/g and did not show any differences between the experiments. At the time of weaning, however, the livers of piglets from large-scale production showed a three times higher content (175 IU/g liver) in comparison to those from traditional production. Highly significant linear relations were established between the vitamin A content of the feed and the liver. According to these, a liver content of vitamin A of approximately equal to 30 IU/g is ensured by approximately equal to 2,000 IU in weaning piglets and by approximately equal to 800 IU vitamin A/kg feed in fattening pigs. The vitamin A activity of the beta-carotene in weaners was ascertained as less than 100 IU/mg. The plasma vitamin A level indicated the vitamin A status only in the range of deficient supply. A different plasma content could not be detected between 1,000 and 4,000 IU vitamin A/kg feed. According to this, a semilogarithmic relation was calculated according to the model of a saturation curve between the vitamin A content of the plasma and the liver. The threshold value for the decrease of the plasma level under 45 IU vitamin A/dl is 35 IU/g liver. Due to the low definiteness measure (B = 0.52) the relation cannot be applied to the individual animal. A contamination of 1,000 mg nitrite/kg feed had a low, and in the course of the experiment decreasing, influence on the vitamin A content of plasma and liver. 相似文献
78.
79.
80.