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   416篇
  免费   16篇
林业   43篇
农学   47篇
基础科学   6篇
  101篇
综合类   20篇
农作物   37篇
水产渔业   47篇
畜牧兽医   83篇
园艺   4篇
植物保护   44篇
  2023年   11篇
  2022年   10篇
  2021年   11篇
  2020年   14篇
  2019年   18篇
  2018年   17篇
  2017年   17篇
  2016年   20篇
  2015年   5篇
  2014年   16篇
  2013年   44篇
  2012年   22篇
  2011年   19篇
  2010年   18篇
  2009年   20篇
  2008年   22篇
  2007年   16篇
  2006年   14篇
  2005年   10篇
  2004年   12篇
  2003年   5篇
  2002年   7篇
  2001年   12篇
  2000年   3篇
  1999年   10篇
  1998年   5篇
  1997年   2篇
  1994年   3篇
  1993年   3篇
  1992年   1篇
  1990年   5篇
  1989年   4篇
  1988年   6篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1979年   2篇
  1977年   1篇
  1976年   2篇
  1971年   1篇
  1967年   1篇
  1966年   3篇
排序方式: 共有432条查询结果,搜索用时 31 毫秒
81.
Batch sorption experiments were carried out to investigate the potentiality of papaya leaf powder (PLP) for the removal of methylene blue (MB) from aqueous solution. The effects of various experimental parameters, such as adsorbent dose, initial solution concentration, contact time, and solution pH were also studied. The amount of dye adsorbed was found to increase with increase in initial dye concentrations. Papaya leaf adsorbs MB better in basic medium. The adsorption equilibrium data fitted well in the Langmuir isotherm equation with a monolayer sorption capacity of 512.55?mg?g?1. The kinetics of MB adsorption onto papaya leaf was examined using the pseudo-first and pseudo-second order and unified approach kinetic models. The adsorption kinetics followed the pseudo-second order kinetic model, but the rate constant was found to depend on initial dye concentration. The unified approach model described the equilibrium and kinetics well. The forward and backward rate constants were determined from the unified approach model.  相似文献   
82.
Phenolic content and discoloration were determined for 13 commercial potato cultivars and 6 potato clones grown at 2 locations over a period of 5 successive years. Tubers from 6 potato cultivars and 5 potato clones resistant to the golden nematode were compared with tubers from 7 potato cultivars and 1 clone known to be susceptible to the golden nematode. Tubers from resistant plants were lower in phenols and discolored less than tubers from susceptible plants.  相似文献   
83.
The effect of freezing on the chemical composition of Katahdin and Atlantic potatoes was studied. Tubers were exposed to a temperature of ?20°C for 24 hrs., then thawed for 1 hr. at 20°C prior to analysis. Frozenthawed tubers were compared with unfrozen controls for total lipid, phospholipid, fatty acid and mineral content. Following freezing, a significant (p<.01) decrease was observed in crude lipid and phospholipid content of both cortex and pith sections. Generally, an increase in palmitic acid and a decrease in linolenic acid occurred in the phospholipid fractions of both varieties. A decrease in both macro and micro mineral content also occurred following freezing.  相似文献   
84.
A study was conducted to compare the nutrient utilization, growth, and rumen enzyme profile of mithun (Bos frontalis) and Tho-tho cattle (Bos indicus) reared in the same feeding and managemental conditions. For the purpose, male mithun (n = 8) and male Tho-tho cattle (n = 8) of 1.5 years age, selected from the farm of National Research Centre on Mithun, Nagaland, India, were fed on mixed-tree-leaves-based ration as per the requirement of NRC (2001) for cattle for 12 months. Average daily gain (ADG), average dry matter intake (DMI), and feed conversion ratio (FCR) for all animals were recorded. A metabolic trial was conducted at 6 months of the experiment to assess the digestibility coefficient of different nutrients and nutritive value of ration. At 12 months of the experiment, rumen liquor was collected from all animals and analyzed for rumen enzyme profiles, viz., carboxymethylcellulase, xylanase, α-amylase, β-glucosidase, α-glucosidase, urease, and protease. It was found that ADG (507.8 g vs 392.8 g), DM intake (6.59 vs 5.85 kg/day) and DMI/W0.75 (98.75 g vs 91.00 g/day), crude protein intake (780 vs 700 g/day), and total digestible nutrient intake (3.65 vs 3.32 kg/day) were higher (p < 0.05) in mithun than cattle. The nitrogen balance was higher and FCR was better (p < 0.05) in mithun compared with cattle. The digestibility coefficient of different nutrients was similar (p > 0.05) between the species. The microbial enzyme profiles of mithun and cattle were not different (p > 0.05). The better growth performance of mithun than cattle as found in the present study clearly indicates that the mithun has higher genetic potential for growth than Tho-tho cattle of north-eastern hilly region of India.  相似文献   
85.
86.
Scarcity of water and emission of greenhouse gases (GHGs) are the two key environmental issues affecting crop production in India.Reducing the carbon footprint (CF) and water footprint (WF) of crop production can help to mitigate the environmental hazards that stem from GHG emissions and water scarcity.The CFs and WFs of three major cereal crops,rice,wheat,and maize,were estimated for the year 2014 under the environmental conditions in India,based on national statistics and other data sources.To...  相似文献   
87.
Nitrate reductase activity (NRA) was studied in pea, a C3 plant, and sorghum, a C4 plant, at various stages of growth and development. Influence of moisture stress and nitrogen application was also observed since these factors have profound influence on growth and development.

In pea, NRA was maximum at pod maturity stage and minimum at flowering stage. In sorghum plant there was gradual increase in NRA upto grain formation followed by a fall in activity at maturity.

Nitrogen treatment as nitrate and ammonia significantly increased nitrate reductase activity over control in both pea and sorghum. Treatment with potassium nitrate was found to stimulate more NRA in pea than with ammonium sulphate. In sorghum, both forms of nitrogen did not differ much in their influence on NRA.

Influence of moisture stress in reducing NRA was more clear in sorghum, a C4 plant than in pea, a C3 plant. In general, control plants recorded low NRA in both the crops when compared to nitrogen treated plants except at pod formation stage in pea.  相似文献   

88.
Plant growth-promoting bacteria (PGPB) Pseudomonas lurida-NPRp15 and Pseudomonas putida-PGRs4 possessing multiple plant growth-promoting traits were isolated from rhizoplane of pea and rhizosphere of garlic, respectively. The effects of individuals and combinations of Pseudomonas spp. with effective root nodulating symbiotic nitrogen fixing Rhizobium leguminosarum-FB1 on plant growth, nutrient uptake and yield of the rajmash plant were studied under greenhouse conditions. Bacterial inoculation resulted in significantly higher values for plant dry biomass, N, P, K, Zn and Fe contents as compared to the uninoculated control. Furthermore, dual inoculation of P. lurida-NPRp15 with R. leguminosarum-FB1 significantly increased root and shoot dry weight, nodulation, nutrient uptake, pod yield, and nutrient content of pods of rajmash VL63 compared to controls, single and triple inoculation. The results of the study indicate the potential of harnessing the benefit of plant growth-promoting and nitrogen-fixing microorganisms to improve the growth and yield of rajmash.  相似文献   
89.
The aim of present study was to explore and document medicinal plants used for the traditional dermatological healthcare management practices by the the Tharu tribal community of Uttar Pradesh. The study was conducted during 2000–2004. Information was gathered from 230 informants residing in 46 villages in Terai region of Indo-Nepal boarder using questionnaires; oral interviews and group discussions. Total 92 medicinal plant species were cited for the preparation of 113 crude drug formulations. Voucher specimens of cited plant species were collected and identified as belonging to 82 genera and 49 families. Thirty-nine medicinal plant species were reported for the first time for dermatological healthcare problems from India. The dermatological healthcare problems managed were cut and wounds, ringworm, leprosy, eczema, scabies, leucoderma, boils, carbuncles, pimples, skin blemishes, spots, eruption, and burns etc. The most commonly and popularly used medicinal plant species for management of dermatological healthcare problems in the study area were Curcuma longa L., Azadirachta indica A. Juss and Melia azedarach L. It is concluded that dermatological healthcare management practice in the study area depends largely on wildly growing medicinal plant species. There is an urgent need to properly conserve the medicinal plant species growing in this area for human welfare. There is also need for further phytopharmacological studies to provide scientific explanation for the usages of 57 medicinal plant species for which to the best of our knowledge phytopharmacological literatures are not available.  相似文献   
90.
Nitrogen in the soil is continually undergoing transformation, changing in form and availability. All phases of the cycle through which this element passes must be considered in attempting to explain nitrogen balances, losses or gains. Processed such as ammonification, nitrosofication, nitrification, nitrogen fixation, and denitrification need study in this respect. Nitrogen transformations and losses in soils have been investigated extensively in various countries and exhaustive reviews of a general nature1),8,,9),15) are available.  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