全文获取类型
收费全文 | 416篇 |
免费 | 63篇 |
国内免费 | 1篇 |
专业分类
林业 | 31篇 |
农学 | 9篇 |
基础科学 | 1篇 |
91篇 | |
综合类 | 55篇 |
农作物 | 50篇 |
水产渔业 | 26篇 |
畜牧兽医 | 156篇 |
园艺 | 15篇 |
植物保护 | 46篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 9篇 |
2020年 | 13篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 21篇 |
2011年 | 24篇 |
2010年 | 21篇 |
2009年 | 6篇 |
2008年 | 24篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1979年 | 3篇 |
1975年 | 3篇 |
1963年 | 5篇 |
1962年 | 3篇 |
1960年 | 4篇 |
1959年 | 3篇 |
1954年 | 3篇 |
1937年 | 4篇 |
1936年 | 6篇 |
1935年 | 3篇 |
1925年 | 3篇 |
1924年 | 6篇 |
排序方式: 共有480条查询结果,搜索用时 31 毫秒
91.
Bitters Matthew E. Hicks Andrew Holtz Spencer Acruri Paulina Wilson Robert Resasco Julian Davies Kendi F. 《Landscape Ecology》2022,37(6):1483-1495
Landscape Ecology - Earth's forests are fragmented. Species' long-term persistence depends on their conservation in fragmented landscapes with remnants embedded in a matrix of human land... 相似文献
92.
Water use and carbon exchange of a red oak-dominated (Quercus rubra L.) forest and an eastern hemlock-dominated (Tsuga canadensis L.) forest, each located within the Harvard Forest in north-central Massachusetts, were measured for 2 years by the eddy flux method. Water use by the red oak forest reached 4 mm day(-1), compared to a maximum of 2 mm day(-1) by the eastern hemlock forest. Maximal carbon (C) uptake rate was also higher in the red oak forest than in the eastern hemlock forest (about 25 versus 15 micromol m(-2) s(-1)). Sap flux measurements indicated that transpiration of red oak, and also of black birch (Betula lenta L.), which frequently replaces eastern hemlock killed by hemlock woolly adelgid (Adelges tsugae Annand.), were almost twice that of eastern hemlock. Despite the difference between species in maximum summertime C assimilation rate, annual C storage of the eastern hemlock forest almost equaled that of the red oak forest because of net C uptake by eastern hemlock during unusually warm fall and spring weather, and a near-zero C balance during the winter. Thus, the effect on C storage of replacing eastern hemlock forest with a forest dominated by deciduous species is unclear. Carbon storage by eastern hemlock forests during fall, winter and spring is likely to increase in the event of climate warming, although this may be offset by C loss during hotter summers. Our results indicate that, although forest water use will decrease immediately following eastern hemlock mortality due to the hemlock woolly adelgid, the replacement of eastern hemlock by deciduous species such as red oak will likely increase summertime water use over current rates in areas where hemlock is a major forest species. 相似文献
93.
高温蘑菇浙AgH—1种型的鉴定 总被引:2,自引:1,他引:1
本文描述了高温蘑菇浙AgH-1的形态学和生物学特性,该菌株最适出菇温度为27 ̄30℃,子实体能在35 ̄38℃下生长。此外该菌株子实体的口感和风味明显优于以往文献报道的双环蘑菇,因此该菌株是双环蘑菇的一个新的生理型。 相似文献
94.
95.
96.
97.
98.
99.
100.
Fertilizer recommendations for citrus production on heavier textured, calcareous soils increase with the age of the tree up to 168 kg N ha−1 year−1 from a soluble source in one or two applications. Such practices may be inefficient and could cause detrimental effects on fruit quality. A variety of fertilization practices are used in South Texas, and additional evaluation is needed. Rates and sources of nitrogen (N), phosphorus (P), and a commercial program consisting of both a soil component containing organic acids and a foliar component were evaluated on grapefruit production for 6 years. Increasing rate of N application increased leaf nutrient concentration, grapefruit yield, and affected fruit shape as indicated by a decrease in the equatorial:polar diameter (E:P) ratio. Since the response to increasing N application by the E:P ratio was linear while grapefruit yield was quadratic, high N application has a negative effect on fruit shape beyond the level of increasing total yield. Phosphorus application had no effect on any parameter measured, even though soil testing indicated soil P levels were below those at which a P response would be expected. Comparisons between granular 21-0-0 applied broadcast and liquid N-32 injected in a band in the soil at the drip line showed an increase in the number of fruit per tree, but no differences in yield. The ‘Actagro’ program greatly improved available soil P levels and increased the juice brix:acidity ratio, but did not affect grapefruit yield. Phosphorus availability may therefore be a factor in improving grapefruit juice quality. The soil profile within the citrus root zone was found to contain large amounts of inorganic N, but availability of this residual N was limited since yield responses occurred at the N application rates applied in this study. The amount of N contained in the fruit harvested was a small fraction, roughly 5–10%, of the residual amount in the soil. While N uptake in the fruit increased with N fertilizer application, the increase in N taken up relative to the amount applied averaged 42%. 相似文献