排序方式： 共有13条查询结果，搜索用时 15 毫秒
1.
Sunspots, dark magnetic regions occurring at low latitudes on the Sun's surface, are tracers of the magnetic field generated by the dynamo mechanism. Recent solar dynamo models, which use the helioseismically determined solar rotation, indicate that sunspots should form at high latitudes, contrary to observations. We present a dynamo model with the correct latitudinal distribution of sunspots and demonstrate that this requires a meridional flow of material that penetrates deeper than hitherto believed, into the stable layers below the convection zone. Such a deep material flow may have important implications for turbulent convection and elemental abundance in the Sun and similar stars. 相似文献
2.
Ranjan Bhattacharyya Arti Bhatia Birendra N. Ghosh Priyabrata Santra Debashis Mandal Gopal Kumar Raman Jeet Singh Madegowda Madhu Avijit Ghosh Arup K. Mandal Ranjan Paul Ashim Datta Parbodh C. Sharma Uttam K. Mandal Pramod Jha Kokkuvayil S. Anil Manickam Lalitha Mahesh Kumar Nav R. Panwar Dibyendu Sarkar Ashok K. Patra Sumanta Kundu Michael A. Fullen Jean Poesen Bhabani Sankar Das Nagarjuna N. Reddy Suresh K. Chaudhari 《European Journal of Soil Science》2023,74(4):e13388
Current widespread and intensive soil degradation in India has been driven by unprecedented levels of population growth, large-scale industrialization, high-yield agriculture, urban sprawl and the spread of human infrastructure. The damage caused to managed and natural systems by soil degradation threatens livelihoods and local services and leads to national socio-economic disruption. Human-induced soil degradation results from land clearing and deforestation, inappropriate agricultural practices, improper management of industrial effluents and wastes, careless management of forests, surface mining, urban sprawl, and ill-planned commercial and industrial development. Of these, inappropriate agricultural practices, including excessive tillage and use of heavy machinery, over-grazing, excessive and unbalanced use of inorganic fertilizers, poor irrigation and water management techniques, pesticide overuse, inadequate crop residue and/or organic carbon inputs, and poor crop cycle planning, account for nearly 40% (121 Mha) of land degradation across India. Globally, human activities related to agriculture contribute to the transgression of four of the nine Planetary Boundaries proposed by Rockström et al. (2009): Climate Change, Biodiversity Integrity, Land-system Change, and altered Phosphorus and Nitrogen Biogeochemical Flows. This review focuses on how knowledge of soil processes in agriculture has developed in India over the past 10 years, and the potential of soil science to meet the objectives of the United Nations' Sustainable Development Goal 2: Zero Hunger (End hunger, achieve food security, improved nutrition and promote sustainable agriculture), using the context of the four most relevant Planetary Boundaries as a framework. Solutions to mitigate soil degradation and improve soil health in different regions using conservation agricultural approaches have been proposed. Thus, in this review we (1) summarize the outputs of recent innovative research in India that has explored the impacts of soil degradation on four Planetary Boundaries (Climate Change, Biodiversity Loss, Land-system Change, and altered Biogeochemical Flows of Phosphorus and Nitrogen) and vice-versa; and (2) identify the knowledge gaps that require urgent attention to inform developing soil science research agendas in India, to advise policy makers, and to support those whose livelihoods rely on the land. 相似文献
3.
Amaresh Kumar NAYAK Rahul TRIPATHI Manish DEBNATH Chinmaya Kumar SWAIN Biswaranjan DHAL Shanmugam VIJAYKUMAR Anshuman Debasis NAYAK Sangita MOHANTY Mohammad SHAHID Anjani KUMAR Manoj RAJAK Khitish Chandra MOHARANA Dibyendu CHATTERJEE Susmita MUNDA Pravat GURU Rubina KHANAM Banwari LAL Priyanka GAUTAM Suschismita PATTANAIK Arvind Kumar SHUKLA Nuala FITTON Pete SMITH Himanshu PATHAK 《土壤圈》2023,33(3):448-462
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
4.
In Vitro and Dietary Effects of Chitin on Cellular and Humoral Immune Parameters of Catla,Catla catla (Hamilton) 
下载免费PDF全文
下载免费PDF全文 Immunostimulants increase the immunocompetency and disease resistance of fish by enhancing immune responses. This study determined the in vitro and dietary effects of chitin on immune responses of catla, Catla catla. Catla head‐kidney leukocytes were cultured in complete RPMI‐1640 medium containing 0.01, 0.1, and 1.0 mg/mL of chitin. Leucocyte viability and different cellular immune responses, namely, respiratory burst, nitric oxide production, and leucocyte peroxidase content were analyzed in vitro. In the dietary experiment, chitin‐supplemented diets (0.5, 1.0, and 2.0% of feed) were fed to catla for 2 wk, and respiratory burst, serum lysozyme, and total protein contents were measured after 1 and 2 wk of feeding. Leucocytes incubated in vitro with chitin for 72 h maintained their viability. Chitin significantly (P < 0.05) enhanced all the immune responses in vitro. The lowest dose showed the best response. Dietary chitin also significantly stimulated all the immune parameters in a dose‐dependent manner with the highest dose showing the maximum responses. All the responses were higher after 1 wk of feeding and declined thereafter. The results suggest that chitin stimulates catla cellular and humoral immune responses in vitro and in vivo. 相似文献
5.
6.
Adjuvant effect of mushroom glucan and bovine lactoferrin upon Aeromonas hydrophila vaccination in catla, Catla catla (Hamilton) 总被引：2，自引：0，他引：2
Mushroom glucan and bovine lactoferrin (Lf), known for their immunostimulatory potential, were used as adjuvant in conjunction with a formalin-killed Aeromonas hydrophila vaccine in catla, Catla catla. In vitro antigen-specific responsiveness of catla leucocytes and protective responses against experimental challenge with homologous antigen were monitored following immunization. Antigen-specific proliferation, 'macrophage activating factor' (MAF) production and antibody production were significantly higher in fish injected with glucan adjuvanted vaccine. Lf adjuvanted preparations showed a weak proliferative response and MAF production, although the antibody production was significantly higher than the controls. A good degree of protection was achieved with the glucan adjuvanted vaccine. However, in spite of producing significant anti-A. hydrophila antibody, Lf adjuvanted vaccine did not confer any protection following challenge with A. hydrophila. The potential of adjuvanticity of mushroom glucan and bovine Lf in intraperitoneal vaccination is discussed. 相似文献
7.
Upadhaya Krishna Barik Saroj Kanta Adhikari Dibyendu Baishya Ratul Lakadong Nigyal John 《林业研究》2009,20(3)
在5个典型自然种群Mylliem(种群1)、Upper Shillong(种群2)、Shillong Peak(种群3)、Laitkor(种群4)和Nongpiyur(种群5)中,详细研究了冬青树(Ilex khasiana)种群结构和再生生态学,旨在探究种群结构和再生能力的影响因素.在全光照(100%),中等光照(50%)和低光照(30%)三种光强度条件下,实验观察表明:在中等和低光照条件下的种苗成活率和生长状态好于在高光照条件下的种苗成活率和生长状态.成年树种群(≥5cm dbh)的密度直径分布揭示了一种再生种群的典型特征.对植被的破坏和人类其他干扰导致森林树冠疏开使光照增强,造成自然种群(L khasiana)幼苗的高死亡率.本研究结果对制定适当的物种保护措施有重要价值. 相似文献
8.
The present study determined the effective concentrations of clove oil and MS‐222 in juvenile rohu Labeo rohita for quick induction and recovery. The immune‐biochemical responses due to 0, 1 and 24 hr exposure to those anaesthetics were also evaluated. Of four concentrations of the anaesthetics examined, the lowest effective concentration of clove oil and MS‐222 were 50 µl/L and 125 mg/L respectively. Clove oil and MS‐222 significantly increased the myeloperoxidase, total protein and alkaline phosphatase activity at some of the holding durations. However, superoxide anion production (after 0 and 1 hr) and antiprotease activity (after 24 hr) were significantly reduced in fish exposed to clove oil. Serum glucose content was significantly elevated in the MS‐222‐treated group. Furthermore, the clove oil‐treated group showed significantly higher levels of serum Na+ and K+, while the aspartate and alanine aminotransferase activities were significantly enhanced in the MS‐222 group. The use of both clove oil and MS‐222 is advised as an anaesthetic agent for rohu with a bias towards clove oil, considering its economic and operational feasibility. 相似文献
9.
Khriezhato Nakhro Anushree Das Dibyendu Kamilya 《Veterinary research communications》2014,38(2):115-122
The effect of immunization on systemic and cutaneous mucosal immune responses of fish and their possible relation with protection has not been fully assessed. In this study, healthy catla (Catla catla) were immunized against Edwardsiella tarda using two antigenic preparations namely, whole cell bacterin (B) and bacterin mixed with Freund’s complete adjuvant in a 1:1 (v/v) ratio (B+A) followed by a booster dose after 3 weeks of first injection. Different systemic and cutaneous mucosal immune responses were measured at weekly interval upto 8th week post vaccination (pv). Fish were challenged 8 weeks pv with live E. tarda to study vaccine induced protection. The result showed that although there were strong systemic as well as mucosal immune responses, particularly after booster dose, the challenge produced low to moderate protection in terms of relative percent survival (RPS). The maximum RPS (50 %) was recorded in the adjuvanted bacterin group after 8 weeks pv. Low to moderate protection after challenge, which may be attributed to the intracellular nature of E. tarda and/or use of crude antigenic preparation, accounts for new strategy to be developed for immunization programme against such intracellular pathogen. The results collectively suggest possible involvement of systemic as well as mucosal immune responses in inducing protective immunity in catla. 相似文献
10.
Dibyendu Talukdar 《Journal of Crop Science and Biotechnology》2012,15(4):325-334
The effect of calcium (Ca) on lentil (Lens culinaris Medic.) seedlings exposed to cadmium (Cd) stress was studied by investigating plant growth and antioxidant enzyme activities. Plants were grown for 14 days in full-strength Hoagland nutrient media supplemented with Cd concentrations of 0, 10, 20, and 40 μM, and on corresponding medium supplied with 5 mM Ca(NO3)2 prior to Cd addition. Increasing Cd led to accumulation of metal and reduced the fresh weight of the shoots more strongly than that of the roots. Cd concentrations of 20 and 40 μM were selected to study its toxic effect on seedlings. Activities of superoxide dismutase, ascorbate peroxidase, catalase, dehydroascorbate reductase, and glutathione reductase decreased at much higher magnitude in the shoots than those observed in the roots under Cd exposure. Failure of antioxidant defense in scavenging of reactive oxygen species was evidenced by abnormal rise in H2O2, resulting in enhancement of lipid peroxidation and membrane electrolyte leakage as the marks of Cd-induced oxidative stress in lentil seedlings. Ca priming in the media significantly reduced the Cd accumulation and considerably alleviated the adverse impact of Cd treatment by modulating the antioxidant enzyme activity. Mitigation of Cd-induced stress by Ca application was strongly suggested by declining levels of H2O2 and consequent lowering of oxidative damage of membrane. Consequently, this enhanced fresh mass of plant parts as the sign of Ca-mediated normal growth in Cd-treated lentil seedlings. 相似文献