全文获取类型
收费全文 | 135709篇 |
免费 | 7794篇 |
国内免费 | 66篇 |
专业分类
林业 | 5576篇 |
农学 | 4644篇 |
基础科学 | 862篇 |
17494篇 | |
综合类 | 18961篇 |
农作物 | 5091篇 |
水产渔业 | 7092篇 |
畜牧兽医 | 73026篇 |
园艺 | 1798篇 |
植物保护 | 9025篇 |
出版年
2020年 | 1187篇 |
2019年 | 1410篇 |
2018年 | 2229篇 |
2017年 | 2490篇 |
2016年 | 2295篇 |
2015年 | 1999篇 |
2014年 | 2452篇 |
2013年 | 5731篇 |
2012年 | 4355篇 |
2011年 | 5163篇 |
2010年 | 3502篇 |
2009年 | 3550篇 |
2008年 | 5152篇 |
2007年 | 4970篇 |
2006年 | 4642篇 |
2005年 | 4262篇 |
2004年 | 4110篇 |
2003年 | 4174篇 |
2002年 | 3808篇 |
2001年 | 4773篇 |
2000年 | 4643篇 |
1999年 | 3748篇 |
1998年 | 1471篇 |
1997年 | 1452篇 |
1996年 | 1341篇 |
1995年 | 1599篇 |
1994年 | 1327篇 |
1993年 | 1361篇 |
1992年 | 2762篇 |
1991年 | 2901篇 |
1990年 | 2866篇 |
1989年 | 2897篇 |
1988年 | 2610篇 |
1987年 | 2592篇 |
1986年 | 2539篇 |
1985年 | 2400篇 |
1984年 | 1956篇 |
1983年 | 1715篇 |
1982年 | 1154篇 |
1979年 | 1649篇 |
1978年 | 1284篇 |
1977年 | 1135篇 |
1976年 | 1100篇 |
1975年 | 1164篇 |
1974年 | 1357篇 |
1973年 | 1448篇 |
1972年 | 1378篇 |
1971年 | 1195篇 |
1970年 | 1247篇 |
1969年 | 1146篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
Two experiments were conducted to study the effect on nutrient loss and feeding value of making hay by different means, using a barn-drier, a forage-harvester, a crimper and conventional tedding. Both forage-harvesting and crimping of the herbage significantly increased the rate of drying, compared with tedding alone. In Exp. 2 this effect enabled the crimped and forage-harvested hays to be baled for storage 3 days earlier than the tedded hay. The use of the forage-harvester significantly reduced the yield of herbage compared with conventional mowing. Nutrient losses from cutting until storage were highest for the forage-harvested hays, the loss of dry matter between cutting and storage in the forage-harvested hays being 39·9 and 19·3%, respectively, in Expt 1 and 2 with corresponding losses in the conventionally made hays of 7·1% and 9·3%. Crimping the hay resulted in higher nutrient losses than tedding. In Expt 2 there was a loss of dry matter of 17·5% in the conventionally made hay during an 18-week storage period, compared with 3·6% in barn-dried hay, 10·8% in forage-harvested hay and 8·8% in crimped hay.
In Expt 2, in which digestibility determinations were made, conservation decreased the total digestible nutrients and starch equivalent in all treatments. The use of the barn-drier gave the most efficient conservation of total digestible nutrients, followed by the crimped, forage-harvested and conventional treatments in that order. The starch equivalent values of hays made from the same sward were 43·0 when barn-dried, 39·8 when crimped, 38·6 after forage-harvesting and 31·6 after tedding. 相似文献
In Expt 2, in which digestibility determinations were made, conservation decreased the total digestible nutrients and starch equivalent in all treatments. The use of the barn-drier gave the most efficient conservation of total digestible nutrients, followed by the crimped, forage-harvested and conventional treatments in that order. The starch equivalent values of hays made from the same sward were 43·0 when barn-dried, 39·8 when crimped, 38·6 after forage-harvesting and 31·6 after tedding. 相似文献
25.
26.
27.
28.
29.
M. Postner 《Forstwissenschaftliches Centralblatt》1964,83(1-2):33-38
Ohne Zusammenfassung 相似文献
30.