首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   295篇
  免费   18篇
林业   22篇
农学   19篇
  31篇
综合类   12篇
农作物   6篇
水产渔业   58篇
畜牧兽医   115篇
园艺   2篇
植物保护   48篇
  2022年   7篇
  2021年   10篇
  2020年   3篇
  2019年   4篇
  2018年   7篇
  2017年   11篇
  2016年   14篇
  2015年   16篇
  2014年   14篇
  2013年   22篇
  2012年   33篇
  2011年   13篇
  2010年   12篇
  2009年   15篇
  2008年   16篇
  2007年   17篇
  2006年   16篇
  2005年   9篇
  2004年   15篇
  2003年   19篇
  2002年   11篇
  2001年   12篇
  2000年   9篇
  1999年   1篇
  1998年   1篇
  1996年   1篇
  1994年   1篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
排序方式: 共有313条查询结果,搜索用时 15 毫秒
31.
Effects of temperature on food consumption, growth and oxygen consumption were estimated for the freshwater prawn Macrobrachium rosenbergii postlarvae at 23 °C, 28 °C and 33 °C in the laboratory. The results showed that the animal's initial body weight had a close linear relationship with food consumption and growth. Food consumption increased directly with temperature. Consumption rates (C; mg day?1 ind?1 ) of the 28 °C and 33 °C groups were much higher than that of the 23 °C group (P < 0.001), and the 33 °C group's consumption rate was higher than that of the 28 °C group (P < 0.05). The relationship of food consumption with temperature and initial body weight (W; mg) could be described as: C = 0.0679W + 0.185t? 3.17. Growth increased significantly with increased temperature. The relationship among specific growth rate, temperature and initial body weight was as follows: SGR = ?0.110W + 0.213t + 0.176. However, temperature showed no effect on growth efficiency. Oxygen consumption increased significantly with temperature (P < 0.01). The weight‐specific oxygen consumption rates (mg O2 g?1 h?1) at 23 °C, 28 °C and 33 °C were 0.83, 1.16 and 1.49 mg O2 g?1 h?1 for 61.92 mg M. rosenbergii.  相似文献   
32.
33.
Blood total antioxidant capacity (TAC) has become a key bio‐marker for animal health. Forest‐grazing cattle are known to forage various native plants that have high TAC. This study evaluated differences of plasma TAC between forest‐grazing (FG) and pasture‐grazing cattle (PG). Experiment 1 monitored the plasma TAC levels of 32 Japanese Black cattle. The level in PG did not change throughout the grazing period. However, that in FG, which increased from summer, was significantly higher than that in PG through fall (P < 0.05). In experiment 2, we used nine Japanese Black heifers and investigated their blood antioxidant parameters and the TAC in plants that the cattle consumed in late June and September. The plasma TAC levels in FG were significantly higher than those in PG in both periods (P < 0.05). Plasma levels of lipid peroxidation in FG tended to be lower than that in PG (P = 0.098). Furthermore, the TAC levels in various species of shrubs and trees consumed by FG were higher than those in pasture grasses. Results of this study show that plasma TAC of grazing Japanese Black cattle in forestland increase from summer through fall.  相似文献   
34.
35.
The majority of off-type plants in indica hybrid rice were CMS and its maintainer lines.  相似文献   
36.
37.
We compared the greenhouse gas (GHG) emissions from a log pile (LP) to those from a sand compaction pile (SCP) and from cement deep mixing (CDM) as measures against soil liquefaction, assuming that forest and waste management scenarios influence the GHG (CO2, CH4, and N2O) balance of wood. We found little difference between the LP and SCP methods with respect to GHG emissions from fossil fuel and limestone consumption. However, GHG emissions from the CDM method were seven times higher than emissions from the LP method. In the GHG balance of wood, when the percentage of CH4 emissions from carbon in underground wood was lower than 3.3%, permanent storage in the log achieved greater reductions in GHG emissions than using the waste log as fuel in place of coal or heavy oil. In order to obtain reductions in GHG emissions by replacing SCPs or CDM with LPs, sustainable forest management with reforestation and prevention of CH4 emissions from the underground log are essential. Using reforestation, permanent storage of the log, no CH4 emission from the log, and using logging residues instead of coal, the LP can achieve reductions in GHG emissions of 121 tonnes of CO2 per 100 m2 of improvement area by replacing CDM.  相似文献   
38.
The filamentous fungus flora on standing leaves of Typha latifolia in a bog was followed from late spring to early winter. A seasonal successional change of fungal colonizers was observed. Certain groups of species tended to be specific to a particular physiological condition of leaves. Leaf parasites and common primary saprophytes were major colonizers on the developing leaves. After the flowering time of host plant, facultative parasites invaded the aged leaves and finally became dominant on the dead leaves in early winter. A species of Fusarium, F. chlamydosporum was recognized as a main decomposer of the dead leaves near the water line in 1992. It may largely contribute to a smooth supply of dead aerial leaves for the heterotrophic community in the water.  相似文献   
39.
Multiplex PCR is practically a reasonable choice for molecular marker-assisted selection in potato breeding. We had developed and were using a multiplex PCR method for selection of resistance genes to cyst nematode (H1), Potato virus X (Rx1) and late blight (R1 and R2). Since then, more reliable and tightly linked markers for H1 and R2, and a new marker for resistance to Potato virus Y (Ry chc ) were developed. In this article, all these superior markers, including a positive marker to eliminate PCR-failed samples, were incorporated into one multiplex PCR assay. Using the newly developed multiplex PCR technique, five plants potentially harboring all five resistance genes were selected from 96 hybrid plants approximately 5 h after DNA extraction, which is a third of the operation time compared with separate PCR reactions for each marker.  相似文献   
40.
Control of integrin affinity for ligands (integrin activation) is essential for normal cell adhesion, migration, and assembly of an extracellular matrix. Integrin activation is usually mediated through the integrin beta subunit cytoplasmic tail and can be regulated by many different biochemical signaling pathways. We report that specific binding of the cytoskeletal protein talin to integrin beta subunit cytoplasmic tails leads to the conformational rearrangements of integrin extracellular domains that increase their affinity. Thus, regulated binding of talin to integrin beta tails is a final common element of cellular signaling cascades that control integrin activation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号