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   219篇
  免费   20篇
  国内免费   1篇
林业   21篇
农学   20篇
基础科学   7篇
  41篇
综合类   9篇
农作物   18篇
水产渔业   13篇
畜牧兽医   87篇
园艺   6篇
植物保护   18篇
  2023年   4篇
  2022年   7篇
  2021年   3篇
  2020年   3篇
  2019年   9篇
  2018年   14篇
  2017年   10篇
  2016年   11篇
  2015年   10篇
  2014年   8篇
  2013年   39篇
  2012年   9篇
  2011年   12篇
  2010年   21篇
  2009年   12篇
  2008年   16篇
  2007年   6篇
  2006年   7篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2001年   4篇
  1999年   1篇
  1998年   2篇
  1997年   2篇
  1996年   4篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1988年   3篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1965年   1篇
排序方式: 共有240条查询结果,搜索用时 31 毫秒
91.
92.
Abstract

White grubs are highly polyphagous and most destructive soil pests inflicting damage to a wide variety of crops. In India, more than 1000 species of white grubs are known of which over 40 species attack wide range of plants. White grubs are naturally infected by various entomopathogens which include fungi, bacteria and nematodes. Entomopathogenic fungi offer great potential and members of genera Beauveria and Metarhizium are widely used against white grubs. Several commercial products of entomopathogenic fungi like Bio Green, ORY-X, Grub X 10G, Betel, Biotrol FMA and Meta-Guard have been developed for the control of white grubs. In India, good control of white grubs in paddy, ginger and sugarcane has been achieved with different entomofungi. Among EPNs, Heterorhabditis bacteriophora is moderately effective against Popillia japonica and Rhizotrogus majalis. H. indica and H. bacteriophora are effective against potato white grubs in India. Paenibacillus popilliae cause milky disease in P. japonica grubs. The bacterium is pathogenic to Holotrichia consanguinea, H. serrata and Leucopholis lepidophora. In north-western Himalaya, B. cereus is highly toxic to the grubs of H. seticollis and Anomala dimidiata.  相似文献   
93.
A 2-month preliminary study was conducted to delineate the effect of dietary methyl donors (choline, betaine, and lecithin) on the growth performance and metabolic status of Labeo rohita fingerlings subjected to endosulfan alone and in combination with elevated temperature. Four iso-caloric and iso-nitrogenous diets viz. basal diet, betaine-supplemented diet, choline-supplemented diet and lecithin-supplemented diet were prepared and fed to the different experimental groups throughout the experimental period as per the design. Two hundred and seventy fingerlings (average weight 7.95?±?0.04?g) were randomly distributed in six treatment groups each having three replicates. The experimental groups were as follows: fish subjected to normal water (without endosulfan) and fed with control diet (control group T(0)), fish subjected to endosulfan-treated water and fed with control diet (T(1)), fish subjected to concurrent exposure of endosulfan and elevated temperature and fed with control diet (T(2)), fish subjected to endosulfan and elevated temperature and fed with choline-supplemented diet (T(3)), fish subjected to endosulfan and temperature and fed with betaine-supplemented feed (T(4)), and fish subjected to endosulfan and temperature and fed with lecithin-supplemented feed (T(5)). The result shows that in both the groups, that is, endosulfan exposed and concurrent exposure to endosulfan and elevated temperature group of L. rohita the growth performance like percentage weight gain, feed conversion ratio and specific growth rates were significantly different (P?相似文献   
94.
通过探索性调查,本文采用多级随机抽样的方法对孟加拉东北部地区棕榈藤企业的地区贸易模式、经济效益和销售体系进行了评估。根据总投资额,企业分为大型、小型和中型。多数企业家(36.67%)的年龄在30-40或40-50之间。在小型企业中,高学历企业主的比例最低,只有3.33%;而大型企业中的高学历企业主占13.33%成熟企业者。多数企业为小型企业,为46.67%;60%的工人为熟练工,只有40%为非熟练工。经调查,这些企业生产了14种藤产品,共为23个不同尺寸,其中包括沙发(尺寸为45cm×45cm、50cm×50cm和55cm×55cm),餐桌椅系列(4把椅子和一张桌子,或6把椅子和一张桌子)、床(1cm×2cm、1.3 cm×2.3 cm和1.5 cm×2.3 cm)、椅子(45cm×45cm和50cm×50cm)、摇椅(大、中、小)、隔板、花瓶、镜框、手工艺品、台灯、手杖、茶桌等。在大型企业中,生产最多的是椅子(45cm×45cm),而中小型企业的产品中以椅子(50cm×50cm)和手工品居多。在这3种企业中,床(1.5cm×2.3cm)的生产量最少。在大型企业中,总净效益为185 659塔卡,效益成本比为1:18,均为最高。在这3种企业中,大型企业的利润最高。  相似文献   
95.
96.
A viral epidemic associated with the Cherry leaf roll virus (CLRV) has emerged in Betula species in Fennoscandia, exhibiting quick and effective spread during the last 15 years. A population genetics approach is chosen in order to characterise the virus diversity and the sources of genetic variation aiming to investigate the epidemiology of the pathogen. In a CLRV population from Rovaniemi urban parks and a population that occurred after infecting young Betula seedlings with scions from the original Finnish trees, the genetic diversity is found to be remarkably high, mixed infections by CLRV variants from different phylogenetic groups are detected in single trees, while recombination is evidenced to occur. The estimated genetic variability is high and the CLRV haplotypes detected exhibit clear clustering and belong to different phylogenetic groups. The structure of the viral population reveals a pathogen with high evolutionary potential assumed to carry on its effective spread.  相似文献   
97.
98.
本研究旨在通过比较沙棘籽油(Hippophae rhamnoides)和防腐软膏(5%碘伏)、草本软膏(印度草药研究与供应有限公司)及一种刺激性温和的基础药膏(液体石蜡),来研究沙棘籽油对牛的皮肤伤口愈合效果。这个实验是将12头雄性牛犊分为4组,6头牛都有皮肤伤口,3头胸背部脊椎区的两边都用当地的镇痛药。伤口分别用液体石蜡、5%的碘伏软膏、沙棘籽油(沙棘油)及草本软膏处理28d,并分为Ⅰ、Ⅱ、Ⅲ、Ⅳ四组。不同处理的功效是建立在对经过0d、3d、7d、10d、14d和28d的不同临床血液参数的研究基础之上的。在研究中,所有组的心脏、呼吸率和血液学的各种参数及肛温都维持在正常的生理极限内。沙棘油和草本软膏对伤口处理的临床研究中发现,在伤口愈合的初期,伤口保持了一定的干燥度,并且抑制了炎症初期伤口的恶化。不同的组之间,在持续28d的实验中,用草本软膏和沙棘油做处理的组中伤口的愈合率最高。这些组的伤口试验同时还表现出早治疗,早治愈的特征。但是,在草本软膏和沙棘油处理组中,草本软膏组处理的伤口的整体愈合能力还是略优于沙棘油的疗效。  相似文献   
99.
Sixty soil samples (0–0.15 m depth) collected randomly from different districts of Himachal Pradesh were used to evaluate ammonium bicarbonate-diethylenetriaminepenta acetic acid (AB-DTPA) and acid ammonium acetate-ethylene diamine tetra acetic acid (AAAc-EDTA) over standard methods for P, K, and micronutrient cations. Among Olsen P, Bray P1, AB-DTPA P, and AAAc-EDTA P, available P (kg ha?1) varied from 7.8 to 44.3, 9.5 to 61.1, 6.5 to 38.8, 10.5 to 52.1; available K (kg ha?1) among NH4OAc, AB-DTPA, and AAAc-EDTA ranged from 103.6 to 372.3, 86.6 to 364.9, and 74.6 to 362.5. In case of micronutrients cations, AB-DTPA in general, extracted more amounts as compared to DTPA alone. AAAc-EDTA correlated highly with the Olsen P. AB-DTPA-K and AAAc-EDTA-K correlated well with standard method (NH4OAc) however; AAAc-EDTA had higher correlation with AB-DTPA for K extractability. Among methods for micronutrients highest significant correlations were observed between AB-DTPA and DTPA for Cu, Fe, and Zn.  相似文献   
100.
Lavandula stoechas L. plant is a perennial evergreen used as a fragrant ornamental and medicinal plant. In order to study the effect of foliar spray of zinc sulfate (ZnSO4) (0, 1000, and 2000 mgL?1) and sodium chloride (NaCl) salinity (0, 75, and 150 mM) on some physiological characteristics of Lavandula stoechas L. plants, a pot experiment was carried out at the Research Greenhouse of Azarbaijan Shahid Madani University, Iran. Physiological characteristics [root and leaf dry weights, total soluble solids (TSSs), total anthocyanins, chlorophyll b, Zn2+, potassium (K+) contents, and K+/Na+ ratio] were significantly affected by the interaction effects of ZnSO4 foliar application and salinity levels. The highest root dry weight, chlorophyll b, anthocyanin, and Zn contents as well as TSS were found in the plants with NaCl0 × ZnSO4 2000 mgL?1. For Na+, the greatest value was recorded with NaCl 150 × ZnSO40. The highest K+/Na+ ratio was found in the control plants. Foliar application of ZnSO4 promoted the total phenolic content, especially at 2000 mgL–1. The highest amounts of flower dry weights were recorded at NaCl0. Chlorophyll a, total flavonoids, stem dry weight, and essential oil content were affected with ZnSO4 treatment and salinity levels. The highest values for the essential oil content, chlorophyll a content, and stem dry weight were attained by the nonsaline treatment. Both foliar application levels positively influenced the essential oil and flavonoid contents of the plants. The results reveal that zinc application had marked effects on the physiological characteristics of Lavandula stoechas L. plants growing under salinity stress conditions.  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