全文获取类型
| 收费全文 | 26011篇 |
| 免费 | 232篇 |
| 国内免费 | 170篇 |
专业分类
| 林业 | 1060篇 |
| 农学 | 250篇 |
| 基础科学 | 88篇 |
| 3579篇 | |
| 综合类 | 5942篇 |
| 农作物 | 844篇 |
| 水产渔业 | 242篇 |
| 畜牧兽医 | 13460篇 |
| 园艺 | 160篇 |
| 植物保护 | 788篇 |
出版年
| 2018年 | 47篇 |
| 2016年 | 45篇 |
| 2015年 | 61篇 |
| 2014年 | 73篇 |
| 2013年 | 70篇 |
| 2012年 | 2192篇 |
| 2011年 | 2491篇 |
| 2010年 | 538篇 |
| 2009年 | 387篇 |
| 2008年 | 2153篇 |
| 2007年 | 2196篇 |
| 2006年 | 1941篇 |
| 2005年 | 1930篇 |
| 2004年 | 1801篇 |
| 2003年 | 1648篇 |
| 2002年 | 1510篇 |
| 2001年 | 1018篇 |
| 2000年 | 1296篇 |
| 1999年 | 505篇 |
| 1998年 | 100篇 |
| 1997年 | 85篇 |
| 1996年 | 112篇 |
| 1995年 | 158篇 |
| 1994年 | 155篇 |
| 1993年 | 163篇 |
| 1992年 | 185篇 |
| 1991年 | 201篇 |
| 1990年 | 198篇 |
| 1989年 | 165篇 |
| 1988年 | 185篇 |
| 1987年 | 194篇 |
| 1986年 | 156篇 |
| 1985年 | 128篇 |
| 1984年 | 165篇 |
| 1983年 | 148篇 |
| 1982年 | 116篇 |
| 1981年 | 85篇 |
| 1980年 | 78篇 |
| 1979年 | 76篇 |
| 1978年 | 37篇 |
| 1976年 | 46篇 |
| 1974年 | 43篇 |
| 1970年 | 40篇 |
| 1963年 | 69篇 |
| 1960年 | 40篇 |
| 1959年 | 44篇 |
| 1958年 | 44篇 |
| 1957年 | 69篇 |
| 1954年 | 40篇 |
| 1953年 | 37篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
81.
82.
83.
Fausto-Sterling A 《Science (New York, N.Y.)》1996,273(5279):1158b-1158
84.
85.
Six-year-old cloned Betula pubescens Ehrh. trees, grown outdoors at 65 degrees 01' N, were cut on six dates during the growing season to study coppice shoot development in relation to root-produced cytokinin-like compounds. Bleeding sap was collected over timed intervals for two days after cutting, and endogenous cytokinin-like compounds were measured by ELISA assay in HPLC-purified fractions of xylem sap. Initiation and development of coppice shoots on the clonally propagated plants were comparable to those in seedlings. Coppice shoot initiation was affected by the time of cutting, diminishing significantly after June. Of the cytokinin-like compounds detected in the xylem sap, zeatin riboside-like (ZR) compounds were present in the highest concentrations, and the concentrations of dihydrozeatin riboside-like (DHZR) and isopentenyladenoside-like (IPA) compounds were approximately one third and one eighth of the ZR concentrations, respectively. The concentration of cytokinin-like compounds was positively correlated with xylem sap flow rate. The export of cytokinin-like compounds, especially DHZR- and ZR-types, was positively correlated with the initiation and elongation rate of coppice shoots, the number of lateral branches, and the radial growth of the more slowly growing coppice shoots. The export of cytokinin-like compounds collected immediately after cutting may represent the basal value for each tree. This value is probably affected by the size and activity of the root system and may be a relevant estimate for predicting the success of coppicing. 相似文献
86.
Hellemans A 《Science (New York, N.Y.)》1994,266(5182):26-27
87.
88.
89.
90.