全文获取类型
收费全文 | 218篇 |
免费 | 7篇 |
出版年
2019年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 20篇 |
2009年 | 11篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 8篇 |
1956年 | 12篇 |
1955年 | 15篇 |
1954年 | 5篇 |
1953年 | 7篇 |
1952年 | 6篇 |
1951年 | 3篇 |
1950年 | 1篇 |
1949年 | 4篇 |
1948年 | 12篇 |
1947年 | 1篇 |
1946年 | 2篇 |
排序方式: 共有225条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
The Medicago truncatula hypermycorrhizal B9 mutant displays an altered response to phosphate and is more susceptible to Aphanomyces euteiches 下载免费PDF全文
106.
107.
108.
109.
Relationships between photosynthesis, nitrogen and leaf structure in 14 grass species and their dependence on the basis of expression 总被引:8,自引:1,他引:7
The relationships between leaf structure, nitrogen concentration and CO2 assimilation rate ( A ) were studied for 14 grass species grown in the laboratory under non-limiting nutrient conditions. Structural features included leaf thickness and density, and the proportion of leaf volume occupied by different types of tissue (mesophyll, epidermis, vessels and sclerenchyma). Relationships were assessed for data expressed per unit leaf area and fresh mass. The latter was found to be closely related to leaf volume, which allowed us to use A per unit leaf fresh mass ( A fm ) as a surrogate of A per unit leaf volume. Assimilation rate per unit leaf area ( A a ) was positively correlated with leaf thickness and with the amount of mesophyll per unit leaf area; the relationship with leaf nitrogen content per unit area was only marginally significant. A fm was negatively correlated with leaf thickness and positively with fresh mass-based leaf organic nitrogen concentration. A multiple regression involving these two variables explained 81% of the variance in A fm . The value of A fm was also significantly related to the proportion of mesophyll in the leaf volume, but surprisingly the correlation was negative. This was because thin leaves with high A fm and nitrogen concentration had proportionally more mechanically supportive tissues than thick ones; as a consequence, they also had a lower proportion of mesophyll. These data suggest that, in addition to leaf nitrogen, leaf thickness has a strong impact on CO2 assimilation rate for the grass species studied. 相似文献
110.