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   87篇
  免费   3篇
林业   3篇
农学   10篇
  32篇
综合类   4篇
农作物   8篇
水产渔业   3篇
畜牧兽医   20篇
园艺   2篇
植物保护   8篇
  2023年   2篇
  2022年   6篇
  2021年   4篇
  2020年   2篇
  2019年   4篇
  2018年   5篇
  2017年   10篇
  2016年   3篇
  2015年   2篇
  2014年   7篇
  2013年   13篇
  2012年   5篇
  2011年   4篇
  2010年   2篇
  2009年   2篇
  2008年   4篇
  2006年   1篇
  2004年   4篇
  2002年   2篇
  2001年   2篇
  2000年   3篇
  1996年   2篇
  1990年   1篇
排序方式: 共有90条查询结果,搜索用时 0 毫秒
41.
ABSTRACT

Phosphorus (P) fertilizer source and plant density are considered some of the most important factors affecting crop growth and yield. A field experiment was conducted to determine the impact of P source [zero-P control, DAP (diammonium phosphate), SSP (single super phosphate), and NP (nitrphos)] and plant density (D1 = 40,000, D2 = 60,000, D3 = 80,000, and D4 = 100,000 plants ha?1) on growth and yield of maize (Zea mays L cv. Azam) on a P-deficient soil (6.6 mg P kg?1) at New Developmental Agricultural Research Farm, North-West Frontier Province (NWFP) Agricultural University, Peshawar, Pakistan, during summer 2006 in wheat-maize cropping system. Physiological maturity was delayed, plant height was increased and leaf area was decreased significantly when maize was planted at highest (D4) than at lowest plant density (D1). Application of SSP resulted in earlier physiological maturity of maize than other P fertilizers. Grain and stover yield, harvest index, shelling percentage, thousand grain weight and grains ear?1 were maximized at D3 (80,000 plants ha?1) and with application of P fertilizer. Highest benefit in growth and grain yield was obtained with application of DAP to maize planted at D3. Application of DAP at D3 gave 15, 29, and 19% higher grain yield than its application at D1, D2, and D4, respectively. In conclusion, the findings suggest that growing maize at 80,000 plants ha?1 applied with DAP can maximize productivity of maize in the wheat-maize cropping system on P-deficient soils.  相似文献   
42.
明确减量优化施肥和增施钙镁肥对平和琯溪蜜柚产量、品质和碳排放的影响,为琯溪蜜柚绿色提质增效施肥技术提供科学依据。在蜜柚主产区平和县坂仔镇布置6个田间试验点,设置农户常规施肥(FFP)、优化施肥(OPT,减量施用氮磷钾肥)和优化施肥+钙镁肥(OPT+Ca Mg)处理,研究不同施肥处理对蜜柚产量、品质、肥料偏生产力、经济效益和碳排放的影响。结果表明:①与FFP处理相比,OPT和OPT+Ca Mg处理减肥不减产,且OPT+Ca Mg处理可以显著降低果实的可滴定酸含量(降幅7.0%)、提高固酸比(增幅8.8%),部分试验点可溶性固形物含量存在显著差异,但平均可溶性固形物含量无显著差异,不同处理的果实可食率无显著差异;  相似文献   
43.
A total of 956 quarter milk samples from 253 traditionally managed lactating camels were collected aseptically from Negele (Borena Region), Dire Dawa, and Gewane (Afar Region), Ethiopia, according to multi-stage sampling. The quarter milk samples were subjected to California Mastitis Test (CMT), Somatic Cell Counts (SCC) and bacteriological examinations. Five hundred and seventy one (59.7%) quarter milk samples had microorganisms. Of these, 428 (75.0%) had isolates that were identified as major pathogens (MAP) and 143 (25.0%) as minor pathogens (MIP). A positive correlation was found between CMT scores and bacteriological classes (MAP, MIP) (p-value = 0.00). Strong correlation (p-value = 0.00) between CMT scores and SCC was recorded. The differences among the median log SCC of bacteriological classes (MAP, MIP) were not significant (p-value = 0.24). Similarly, the application of the cut-off level of 2.5 x 10(5) ml(-1) indicated less agreement (p-value = 0.32) for bacteriological classes MAP and MIP.  相似文献   
44.
45.
Three new compounds, (7E)-2beta,3alpha-dihydroxy-megastigm-7-en-9-one (1), 3-[5,7-dihydroxy-2-(4-methoxyphenyl)-4-oxo-4H-chromen-8-yl]-4-methoxybenzoic acid (2), and 4'-O-methyl myricetin 3-O-(6-O-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside (3), were isolated from Ginkgo biloba, together with 27 known compounds. The structures of the new compounds were determined primarily from 1D- and 2D-NMR analysis. The 4-O-methylbenzoic acid structural feature at C-8 in 2 is encountered for the first time. The antioxidant activities of 29 compounds isolated from Ginkgo biloba were evaluated on intracellular reactive oxygen species in HL-60 cells. It was found that quercetin, kampferol, and tamarixetin had antioxidant activity that was approximately 3-fold greater than that of their respective glycosides and also approximately 3-fold greater than that of a standard ascorbic acid with an IC(50) at maximum effectiveness.  相似文献   
46.
Genetic Resources and Crop Evolution - This is the first report evaluating the genetic diversity of Mexican grape species utilizing DNA-based markers to understand the distribution of grape...  相似文献   
47.
Red delicious apples were used to produce natural apple cider with and without inclusion of maceration. Traditional surface and industrial submersion methods were then applied to make vinegar from apple ciders. Apple cider vinegar samples produced with inclusion of maceration in the surface method had the highest total phenolic content, chlorogenic acid, ORAC, and TEAC levels. Cholesterol and apple vinegar samples were administered using oral gavage to all groups of rats except the control group. Apple cider vinegars, regardless of the production method, decreased triglyceride and VLDL levels in all groups when compared to animals on high-cholesterol diets without vinegar supplementation. Apple cider vinegars increased total cholesterol and HDL and LDL cholesterol levels and decreased liver function tests when compared to animals on a high-cholesterol diet without vinegar supplementation. A high-cholesterol diet resulted in hepatic steatosis. VSBM and VSB groups significantly decreased steatosis.  相似文献   
48.
Tropical Animal Health and Production - A prospective study was conducted from November 2013 to February 2014 to estimate the spatial clustering; cumulative incidence and risk factors associated...  相似文献   
49.
The levels of oxidative stress markers are an important indicator of the physiological state of the parasite and its host. In the present study levels of lipid peroxidation, glutathione S transferase, glutathione, superoxide dismutase and catalase were determined in the Clinostomum complanatum progenetic metacercaria, obtained from the fish peritoneum (a hypoxic habitat). The in vivo transformed ovigerous adult worms were obtained from the aerobic environment of the buccopharyngeal region of experimentally infected chickens. Levels of antioxidant molecules were also determined in the blood of experimentally infected chickens. An increase in the levels of lipid peroxidation, and a significant decrease in the levels of glutathione S transferase, glutathione, superoxide dismutase and catalase was observed in the infected host as compared to the controls. In the ovigerous worms, the levels of lipid peroxidation, glutathione S transferase, glutathione, superoxide dismutase were found to be significantly less than the levels observed in the progenetic metacercaria. Since the establishment of worm in the buccal cavity of the avian host would lead to its exposure to oxygen and the haematophagous nature of the parasite also exposes it to the free radicals in the host blood, the progenetic metacercaria has evolved to produce excess free radical scavenging molecules reserved to combat the oxidative stress encountered within the microhabitat of the definitive host.  相似文献   
50.
Sewage contains several trace elements of environmental concern, and cadmium (Cd) is one of the most mobile elements in soil–plant system that can pose drastic effects on plants and human health due to its long persistence and non-biodegradability nature in environment. It is necessary to prevent its entry into food chain for better food quality and human health. Present study was designed to evaluate the effectiveness of different water management practices, viz. W1: flooding throughout the growing season, W2: flooding after 4 days of disappearance of standing water (DAD), W3: flooding till heading and after that flooding of soil after 4 days of DAD, W4: Aerobic condition throughout growing season (flooding after 8 days) for reducing Cd concentration in rice grain grown under varying levels of Cd (0, 20, 40 mg kg?1) spiked soil. Results revealed that grain yield declined with increasing Cd levels but maximum plant height (89.3 cm), straw yield (16.9 g) and grain yield (22.5 g pot?1) was observed where pots were flooded till heading and thereafter flooding. Cadmium concentration increased with increasing concentration of Cd in soil. Further, it is added that the lowest Cd concentration in shoot, grain and husk and translocation factor were observed under W3 when the soil was spiked with 40 mg kg?1. In crux, continuous flooding till heading and thereafter flooding after 4 DAD can significantly decrease the grain Cd concentration without compromise on yield.  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