全文获取类型
收费全文 | 4194篇 |
免费 | 286篇 |
国内免费 | 342篇 |
专业分类
林业 | 227篇 |
农学 | 363篇 |
基础科学 | 103篇 |
881篇 | |
综合类 | 1839篇 |
农作物 | 237篇 |
水产渔业 | 451篇 |
畜牧兽医 | 402篇 |
园艺 | 172篇 |
植物保护 | 147篇 |
出版年
2024年 | 20篇 |
2023年 | 63篇 |
2022年 | 109篇 |
2021年 | 138篇 |
2020年 | 157篇 |
2019年 | 174篇 |
2018年 | 122篇 |
2017年 | 196篇 |
2016年 | 220篇 |
2015年 | 179篇 |
2014年 | 199篇 |
2013年 | 245篇 |
2012年 | 304篇 |
2011年 | 271篇 |
2010年 | 282篇 |
2009年 | 288篇 |
2008年 | 200篇 |
2007年 | 217篇 |
2006年 | 206篇 |
2005年 | 156篇 |
2004年 | 141篇 |
2003年 | 119篇 |
2002年 | 120篇 |
2001年 | 116篇 |
2000年 | 90篇 |
1999年 | 78篇 |
1998年 | 49篇 |
1997年 | 65篇 |
1996年 | 44篇 |
1995年 | 41篇 |
1994年 | 51篇 |
1993年 | 31篇 |
1992年 | 31篇 |
1991年 | 17篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有4822条查询结果,搜索用时 15 毫秒
1.
2.
Stuart Fraser Mireia Gomez‐Gallego Judy Gardner Lindsay S. Bulman Sandra Denman Nari M. Williams 《Forest Pathology》2020,50(2)
Phytophthora pluvialis and Phytophthora kernoviae are the causal agents of important needle diseases on Pinus radiata in New Zealand. Little is known about the epidemiology of the diseases, making the development of control strategies challenging. To investigate the seasonality and climatic drivers of sporulation, inoculum traps, consisting of pine fascicles floating on water in plastic containers, were exchanged fortnightly at five sites in P. radiata plantations between February 2012 and December 2014. Sections of needle baits were plated onto selective media and growth of Phytophthora pluvialis and P. kernoviae recorded. To explore the generalizability of these data, they were compared to detection data for both pathogens from the New Zealand Forest Health Database (NZFHDB). Further, equivalent analyses on infection of Rhododendron ponticum by P. kernoviae in Cornwall, UK allowed the comparison of the epidemiology of P. kernoviae across different host systems and environments. In New Zealand, inoculum of P. pluvialis and P. kernoviae was detected between January–December and March–November, respectively. Inoculum of both species peaked in abundance in late winter. The probability of detecting P. pluvialis and P. kernoviae was greater at lower temperatures, while the probability of detecting P. pluvialis also increased during periods of wet weather. Similar patterns were observed in NZFHDB data. However, the seasonal pattern of infection by P. kernoviae in the UK was the opposite of that seen for sporulation in New Zealand. Phytophthora kernoviae was likely limited by warmer and drier summers in New Zealand, but by colder winter weather in the UK. These results emphasize the importance of considering both environmental drivers and thresholds in improving our understanding of pathogen epidemiology. 相似文献
3.
Four sets of durum samples were used in this study to further understand the interrelationships among hard vitreous kernels (HVK), protein content, and pigment concentration, with a focus on the interaction and synergistic effects of protein content and vitreousness on durum quality. HVK level increases with higher protein content in the range of 9.5–12.5%, but this relationship is less evident in durum samples with high protein content (12.5–14.5%). Both protein content and kernel vitreousness can significantly affect durum milling quality. White starchy kernels (WSK) in low protein durum have a very detrimental impact on milling and pasta processing quality, but high protein content can mitigate the adverse impact of WSK on durum quality. Although protein content plays a dominant role, higher HVK might contribute positively to pasta firmness. There was no significant difference in yellow pigment content between HVK and WSK. However, pigment loss from semolina to dough was higher for WSK than HVK. Despite the difference in protein content, HVK and WSK have little difference in gluten strength. The monomeric protein was preferentially accumulated in HVK. The glutenin proteins of HVK and WSK were similar in the ratios of 1Bx/1By and HMW/LMW-GS. 相似文献
4.
在查清天津市园林主要花灌木刺吸口器害虫桃粉蚜、绣线菊蚜、棉蚜和山楂红蜘蛛发生消长规律的基础上 ,确定了防治适期和结合点 ,筛选出 10 %吡虫啉、绿灵、蚧螨灵、 1. 8%齐螨素和花保5种低、无毒药剂 ,防效均达到 90 %以上。查出天敌 13种 ,并对优势种作了取食量调查 相似文献
5.
6.
7.
8.
9.
10.
Field experiments were conducted to characterize the demography of Abutilon theophrasti and Setaria faberi in a conventionally managed 2‐year (maize/soya bean) rotation, and in 3‐year (maize/soya bean/triticale + red clover) and 4‐year (maize/soya bean/triticale + lucerne/lucerne) rotations managed with 72% and 79% lower herbicide inputs respectively. Rates of weed seedling recruitment, seedling survival and adult plant fecundity were determined for populations in each phase of each rotation and used to calculate annual rates of weed population change, Δ. In both years of the study, Δ for A. theophrasti populations declined or remained stable in all three rotation systems. Despite greater rates of seedling survival and fecundity in maize and soya bean in the 3‐ and 4‐year rotations, increases in Δ for A. theophrasti populations were prevented in these systems because of low fecundity in triticale and low seedling survival and fecundity in lucerne. For Setaria faberi populations, Δ remained stable in the 2‐year rotation, increased in the 3‐year rotation in both years, and increased in the 4‐year rotation in 1 year. The results of this study indicate that when herbicide use is reduced, rotations that include triticale and lucerne can facilitate the suppression of A. theophrasti. Rotations that include lucerne can contribute to restraining S. faberi population growth, given adequate levels of seedling mortality in this crop. 相似文献