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排序方式: 共有69条查询结果,搜索用时 15 毫秒
1.
中原地区丹红杨插干造林技术研究   总被引:1,自引:0,他引:1  
丹红杨是中国林业科学研究院2003年培育成功的新一代超速生抗虫杨,雌株。耐桑天牛、易生根、速生(年胸径生长量达5.8 cm,年平均高生长量4.9 m)。为了提高丹红杨的造林成活率,进行了杨树插干深栽造林试验。试验结果表明,丹红杨采用插干深栽造林方法与传统的带根植苗造林相比,具有成本低、成活率高、生长量大等特点,是一种比...  相似文献   
2.
赵潘  刘卫华 《安徽农业科学》2007,35(29):9393-9394
从中原农耕文化的角度将中原文化与企业文化结合在一起,对塑造河南企业文化的影响思想进行了分析。  相似文献   
3.
For species whose decline preceded the modern era and whose distribution is in the developing world, it is difficult to map suitable habitat across its former range. Eld’s deer (Cervus eldi) is an endangered cervid whose range across Southeast Asia was reduced during the last century to disjoint populations in Myanmar and Cambodia. We used ecological data from the present populations to determine landscape and habitat parameters that would help us predict the occurrence of the species in forests not yet surveyed. The suitable-forest GIS model was created using four readily available datasets for elevation, forest type, canopy closure, and human density. Comparison of the GIS model with 24 verified sightings of Eld’s deer during recent large mammal surveys in Cambodia, found 22 sightings (92%) within predicted suitable forest. Use the suitable-forest GIS model to survey a province in southern Lao People’s Democratic Republic, located a single, previously unreported population from 9 patches surveyed. In a separate analysis, a logistic regression model to predict Eld’s deer habitat in Northern Cambodia found percent tree cover, presence of wetlands, and distance to villages as the best predictors of deer, similar to variables used in the GIS model, with the exception of the importance of wetlands. Using mean annual rainfall to rank suitable-forest patches identified in the GIS model indicated dry dipterocarp forests in Northeastern Cambodia and Northern Myanmar have the highest potential to conserve eld’s deer. Examination of the suitable-forest GIS map and current protected areas indicated only Cambodia, with 11% suitable forest protected, has placed sufficient dry dipterocarp forest under protected status. Other Southeast Asia countries have not recognized dry dipterocarp forest as a significant ecotype worthy of conservation status.  相似文献   
4.
Regional mapping of soils helped to identify and map 24 soil-geomorphic units on the Deoha/Ganga–Ghaghara Interfluve in the Upper Gangetic Plains (Himalayan Foreland Basin). On the basis of luminescence ages soil-geomorphic units can be grouped into five members of a Morphostratigraphic Sequence with ages of ≤ 1.7 ka, 1.8–3.6 ka, 4.6–6.4 ka, 6.8–10 ka and > 10 ka. Except for two units with sandy parent material, all the members with loamy parent materials show systematic increase in the degree of soil development from Member QGMS-I to V. Major pedogenic processes are salinization, alkalinization, illuviation, calcrete development and gleying, and degradation of some micromorphological features is observed in the oldest soils.Regional mapping and dating of soils show that the Interfluve between the Deoha/Ganga–Ghaghara rivers is bounded by longitudinal faults, along the bounding rivers. The major longitudinal faults trend N–S or NNE–SSW in the northern region; turn N–S in the central region and take easterly to SEE direction in the south, giving the Interfluve a curvilinear shape. Strike of a set of six transverse extensional normal faults changes from approximately E–W to NEE–SWW in the southernmost region of the Interfluve. Downthrown sides are to the south and to the east in northern region and western region, respectively.Due to the activity of different segments of various transverse faults during a probably dry sub-humid to semi-arid climatic period of 10–5 ka, terminal fans were deposited on the downthrown blocks. Thus, role of extensional tectonics in an overall compressional regime is significant. Also, tilting of smaller blocks leading to the shifting away of large rivers seems to be an additional control on the distribution of soils and sedimentation on the Interfluve.  相似文献   
5.
为了对玉米历史发展有系统的认识,对建国以来三大平原上玉米生产布局的变动特征进行分析归纳,并探讨其发生如此变化的原因。将1949—2020年划分为五个阶段,计算出70多年来玉米生产集中度指数并对三大平原的玉米生产集中度指数进行横向和纵向的对比分析。三大平原间玉米生产集中度指数差距随着时间变化而逐渐增大,其中东北平原和华北平原的玉米生产集中的指数远高于长江中下游平原,2011年之后东北平原玉米生产集中度指数达到40%以上,与华北平原的玉米生产拉开差距。国内玉米生产布局不断向东北和华北平原集聚,东北平原玉米生产集中度占全国玉米生产的近一半。在“粮改饲”政策和针对东北三省一区的玉米生产者补贴政策实施后,我国的玉米种植面积减少,相应的产量也有所下降。  相似文献   
6.
嘉兴平原桑园土壤分类及肥力的调查   总被引:1,自引:0,他引:1  
选择浙北嘉兴平原桑园代表性土壤,进行调查,研究其成因、分类及特性,并对高低产桑园土壤的理化性状进行化验分析,明确了嘉兴平原桑园土壤是历史上由人工堆迭而成,在分类系统上归属于潮湿土纲、正常潮湿土亚纲、潮土土类、暗潮土亚类、堆迭土土属,又分为粘质堆迭土、壤质堆迭土、粉质堆迭土3个土种。在统计众多土壤理化性状数据的基础上,暂拟本区高产桑园土壤16项理化性状,作为本地区桑园地力建设的参考。  相似文献   
7.
江旅冰 《安徽农业科学》2013,41(19):8411-8414,8417
从狭义中原的地理范畴,解读各类历史典籍中所记录的秦汉前中原及与中原相关的地理内容,从中把握秦汉以前中原古代地理发展的历史脉络、地理成就、发展特点及蕴含的历史地理价值。研究认为,在中国区域性地理发展历史中,尤其是秦汉前中原古代地理发展史不仅可以独立成章,而且形成极具理性的中原古代地理体系,并深刻地影响了中国古代地理科学的历史发展过程。  相似文献   
8.
利用经济重心的计算方法,对河南省1997-2011年农业增加值、农用机械总动力、粮食作物播种面积和粮食总产量等4个指标的重心进行了计算,并对重心转移状况加以分析。结果表明:河南省粮食播种面积重心基本保持平稳;河南省农业机械总动力重心总体朝南移动;农业机械化与农业经济发展之间不存在显著正相关关系,粮食增量与农村经济发展需要通过其他途径来实现;河南省农村经济差异总体较小,尤其豫南和豫北地区农业经济发展基本均衡;类似于非典型性肺炎的重大社会灾害也会对农业经济造成危害。  相似文献   
9.
Spot blotch, caused by Cochliobolus sativus, is a serious constraint to wheat production (Triticum aestivum L.) in the warmer plains of South Asia. Fourteen genotypes were tested in Bangladesh, India and Nepal during 6 years (2000–2005) to determine disease severity and resistance stability over these years. We analyzed the area under the disease progress curve per day (AUDPC/day) to assess spot blotch severity, and examined grain yield, 1000-kernel weight (TKW), days to heading, and plant height. Disease severity differed in the 6 years and several genotypes showed low disease severity in all years. A few genotypes had high grain yield and low disease severity in all years. Genotype Altar-84/Ae. Sq. (224)//Yaco, with the lowest disease severity and highest 1000-kernel weight (TKW) and grain yield was also the most stable for spot blotch resistance, TKW and grain yield. Results demonstrated that wheat genotypes with improved spot blotch resistance, high grain yield, acceptable TKW, and plant height are available as a result of the regional and international collaboration in South Asia. Despite this progress, the challenge lies ahead because of an apparent tendency of increasing spot blotch overall severity in the region and decreasing TKW over 6 years (2000–2005). Higher, average night time temperature during the month of March is an indicator showing that wheat crop performance is challenged in two ways—increasing spot blotch severity and decreasing TKW causing lower yield. The results underline the possible effect of changing climatic factors on disease pressure and the continuous need to identify new resistance sources to develop more spot blotch resistant wheat for the warmer Eastern Gangetic Plains of South Asia.  相似文献   
10.
关于平原区的水土保持问题   总被引:3,自引:0,他引:3  
水土流失是指在水力、重力、风力等外营力的作用下,水土资源和土地生产力的破坏和损失,包括土地表层损失和水的损失。我国是世界上水土流失最为严重的国家之一,尤其在山区和丘陵区。随着经济社会的发展,人口、资源、环境矛盾问题日益突出,笔者发现平原区也存在水土流失问题,且由于平原面积大,地貌类型多,加上人为因素的影响,致使平原区水土流失带来的危害日益严重,从贯彻落实新《水土保持法》的角度出发,本文重点介绍平原区水土流失的类型和特点,并提出了治理各种类型水土流失的措施。对于保护平原区的生态环境和促进经济的可持续发展有很重要的意义。  相似文献   
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