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   154篇
  免费   4篇
  国内免费   1篇
林业   21篇
农学   20篇
基础科学   7篇
  39篇
综合类   6篇
农作物   18篇
水产渔业   13篇
畜牧兽医   16篇
园艺   6篇
植物保护   13篇
  2023年   3篇
  2022年   7篇
  2021年   3篇
  2020年   3篇
  2019年   8篇
  2018年   10篇
  2017年   9篇
  2016年   5篇
  2015年   2篇
  2014年   4篇
  2013年   14篇
  2012年   8篇
  2011年   9篇
  2010年   16篇
  2009年   8篇
  2008年   11篇
  2007年   4篇
  2006年   5篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2001年   3篇
  1999年   1篇
  1998年   1篇
  1996年   4篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1965年   1篇
排序方式: 共有159条查询结果,搜索用时 15 毫秒
71.
72.
This paper analyzes the diversity, consumption and gathering patterns, and uses of wild edible plants among the tribal communities living in cold arid region of Indian Himalaya. Eco-geographically, extremely cold climate, open vegetation, strong afternoon winds and loose soils characterize the region. Wild edible plants have special significance in the livelihoods of tribal people particularly during harsh winters when nothing grows on field. We gathered information on 164 wild edible plant species belonging to 100 genera and 37 families sharing 14% of total plants species occurring here. Around 83% plant species were present in pure wild state while 17% were in semi wild state/cultivated occasionally. Wild plants are eaten more as vegetable and it was found that out of 101 plants used as vegetable, 57 are cooked and eaten and the rest (44) eaten raw. The species like Pinus gerardiana, Prunus armeniaca, Hippophae rhamnoides, Bunium persicum are harvested more for commerce in the downtown markets while Lepidium latifolium, Taraxacum officinale, Urtica hyperborea, Capparis spinosa, Fagopyrum tataricum, Malva verticillata, and Rhodiola heterodonta are preferred for their medicinal and nutritional properties locally. Infrastructure development, more tourists flow, agricultural intensification, more jobs and business opportunities have led to rapid changes in the life styles and food habits of the people. Consequently, the age-old tradition of gathering wild edible plants is fading particularly among younger generations. Nevertheless, people do realize the importance of wild edible plants, and therefore to harness the benefits of this unique diversity participatory management and conservation programs, investigations on nutritional and pharmacological attributes, and regulated market support for some important WEPs have taken up in the region.  相似文献   
73.
The present paper reports the development of novel braided structures using polyamide 6.6 fibers for application as artificial anterior cruciate ligaments (ACLs). The developed structures were circular braids, axially reinforced with either a number of core yarns or braided structures. Tensile behavior of these structures was characterized and the effects of number of axial yarns or braids and, the number of yarns used in the axial braids were thoroughly investigated. From the experimental results, it was observed that the braided structures with axial braids could mimic the load-elongation behaviour of native ACL. The average breaking extension and strain at toe region were 30 % and 4.3 % respectively, which are in the range of native ACLs. The maximum breaking force and stiffness achieved with 7 axial braids, each produced using 6 yarns were 274 N and 13.5 N/mm respectively and, both breaking force and stiffess showed linear increase with the number of axial braids as well as number of yarns used in the axial braids. Therefore, it is possible to design an artificial graft using these novel braided sturctures with mechanical properties similar to that of native ACLs, through adjustment of these structural parameters, as these braided structures have much smaller diameter (0.5 mm) than native ACLs (11 mm).  相似文献   
74.
Asian cultivated rice shows allelic variation in sodium transporter, OsHKT1;5, correlating with shoot sodium exclusion (salinity tolerance). These changes map to intra/extracellularly-oriented loops that occur between four transmembrane-P loop-transmembrane (MPM) motifs in OsHKT1;5. HKT1;5 sequences from more recently evolved Oryza species (O. sativa/O. officinalis complex species) contain two expansions that involve two intracellularly oriented loops/helical regions between MPM domains, potentially governing transport characteristics, while more ancestral HKT1;5 sequences have shorter intracellular loops. We compared homology models for homoeologous OcHKT1;5-K and OcHKT1;5-L from halophytic O. coarctata to identify complementary amino acid residues in OcHKT1;5-L that potentially enhance affinity for Na+. Using haplotyping, we showed that Asian cultivated rice accessions only have a fraction of HKT1;5 diversity available in progenitor wild rice species (O. nivara and O. rufipogon). Progenitor HKT1;5 haplotypes can thus be used as novel potential donors for enhancing cultivated rice salinity tolerance. Within Asian rice accessions, 10 non-synonymous HKT1;5 haplotypic groups occur. More HKT1;5 haplotypic diversities occur in cultivated indica gene pool compared to japonica. Predominant Haplotypes 2 and 10 occur in mutually exclusive japonica and indica groups, corresponding to haplotypes in O. sativa salt-sensitive and salt-tolerant landraces, respectively. This distinct haplotype partitioning may have originated in separate ancestral gene pools of indica and japonica, or from different haplotypes selected during domestication. Predominance of specific HKT1;5 haplotypes within the 3 000 rice dataset may relate to eco-physiological fitness in specific geo-climatic and/or edaphic contexts.  相似文献   
75.
A large global land area is affected by saline, alkali (sodic), and acid soil conditions. Cool season food legumes are important crops in many countries with such adverse soils. Tolerant genotypes have been identified in many crops, including legumes. However, very little has been published on selection of tolerant cool season food legume crops. The inadequate knowledge and understanding of the responses of cool season food legume crops to these abiotic stresses, necessitates action by a collaborative network of interdisciplinary teams to make rapid progress in identifying tolerant germplasm and developing cultivars better adapted to unfavorable soil conditions.  相似文献   
76.
77.
The use of risk aversion in plant breeding; Concept and application   总被引:1,自引:0,他引:1  
Summary Variance analysis is used to measure stability (inter-temporal) and adaptability (over space) components of variance with multilocation-multiyear sorghum yield data from India. Adaptability and stability were highly correlated. Only the stability component is relevant for farmers in their adoption decision. Measures of farmer's risk aversion are used to rank genotypes according to preferences which take account both of yield and stability. Since yield differences were large and risk aversion moderate, preference based rankings did not differ markedly from yield based rankings.  相似文献   
78.
On-farm varietal biodiversity was studied through household surveys in two high potential production systems in Chitwan and Nawalparasi districts of the Nepal Terai and in Lunawada sub-district, Gujarat, India. Diversity was extremely low in Chaite rice in the Nepal study area (weighted diversity 0.04) and low in main season rice in the India study area (weighted diversity 0.34). In both areas, one cultivar dominated, CH 45 in Nepal and GR11 in India. In the India study area, biodiversity varied with the socio-economic group and better-off farmers had a greater varietal diversity. Participatory varietal selection (PVS) identified new varieties that farmers preferred. Their adoption by farmers increased on-farm varietal biodiversity within the three cropping seasons studied. Despite the commonly assumed uniformity of high potential production systems, the new varieties occupied specific niches in the farming system. Farmers' preferences for different varieties – there were large differences in quality traits and maturity period among the new varieties – should help to maintain biodiversity. Overall production is expected to increase as each niche becomes occupied increasingly by the best-adapted variety. PVS is a simple and powerful method of increasing food production in the high potential production systems that produce most of the developing world's grain. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
79.
Agroforestry Systems - Agroforestry as a smart agriculture practice has started to get global attention nowadays. The present investigation is based on bamboo-ginger intercropping research carried...  相似文献   
80.
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