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41.
A methodology for evaluating the sustainability of inland wetland systems   总被引:1,自引:0,他引:1  
Sustainable development is a process in which present and future human needs can be satisfied without degrading the socio-environmental systems that they rely upon. Inland wetlands are diverse ecosystems that provide numerous goods and services. Current wetland evaluation methodologies include inventories, monitoring of hydrological and climatic variables, population dynamic studies, mechanistic models, the use of geographical information systems, and measuring of biotic indices. Sustainability evaluation methods, which combine in a systemic approach production efficiency, ecosystem function, environmental services, and social values are required. In this study, a methodological framework was developed and applied to a case in the High Lerma River Basin in Central Mexico. Criteria and indicators comprising the environmental, economic, and social dimensions, as well as systemic attributes such as productivity, stability, resilience, self-reliance, and equity were derived and measured to evaluate wetland management systems. Native species were compared to the predominant carp monoculture system. Results from the evaluated indicators showed that the native species multicultural management system can be a feasible, profitable, and self-reliant conservation and utilization alternative. Some difficulties were faced in finding reliable estimates to be used as reference values, and potential indicators for future, long-term evaluations are proposed. The application of sustainability indicators to wetland management proved to be an objective and trustworthy methodological alternative, which could increase both wetland sustainability and the continuous development of integrated assessment tools for its evaluation.  相似文献   
42.
Are tidal fronts good recruitment areas for herbivorous copepods?   总被引:1,自引:0,他引:1  
Horizontal distributions of phytoplankton biomass and numerical abundance of copepod nauplii were investigated across a tidal front in the northern part of Bungo Channel, the Inland Sea of Japan, in May and June 1988. The frontal area was characterized by abrupt changes in subsurface (3 m deep) temperature and salinity, and by an increased standing stock of phytoplankton. The density of copepod nauplii was lower in the frontal area than in adjacent stratified and mixed areas. The population egg production rate of a predominant copepod species (Paracakmus sp.) was higher due to elevated fecundity on an individual basis in response to increased chlorophyll concentrations, in the frontal zone. However, the frontal population was subjected to higher mortality, probably due to predation by carnivores that were mainly accumulated passively within the area. From these facts, we conclude that tidal fronts are not always good areas for recruitment of herbivorous copepods, although fronts give rise to high standing stocks of phytoplankton.  相似文献   
43.
The spawning season and grounds of red sea bream in Hiuchi-nada, the central part of the Seto Inland Sea, were described using a new method based on monoclonal antibodies for identifying Pagrus major eggs, and the daily egg production (standardized by the incubation time and survival rate) was estimated. At the peak of spawning (May), the ranges of sea temperature, salinity, and chlorophyll a where red sea bream eggs occurred were 14.8–17.4°C, 32.0–33.0, 0.5–4.4 μg/L, respectively. The main spawning grounds of the red sea bream were confirmed as being the areas near the Geiyo Islands, Misaki Peninsula, Saijyo, Niihama. The spatial spread of red sea bream eggs increased with the egg developmental stage. The ranges of daily egg production in 2005 and 2006 were 0.3–19.3 and 0.2–6.7 × 109 eggs/day, respectively. In Hiuchi-nada, aquaculture farms are located close to the spawning grounds, and the potential spawning population from the aquaculture farms equaled or exceeded that of the estimated spawning population obtained by the egg production method. Red sea bream eggs in Hiuchi-nada might be produced by both wild and aquaculture-based spawning populations.  相似文献   
44.
The study of more than 700 charcoals from the Vaccaean settlement of Pintia (Padilla del Duero, Valladolid) provides new local and detailed data about the Iron Age II forest composition in Continental-Mediterranean inland Spain. Pinus gr. sylvestris/nigra (from which an unexpectedly high number of charcoals were identified), together with Mediterranean pines (also highly represented), Juniperus L. and evergreen and deciduous Quercus, were the main taxa living in the area, revealing two different marked biogeographical elements in the late-Holocene landscapes of the Duero basin: Mediterranean and Eurosiberian. On one hand, the results shed new light on the assessment of the origin of Mediterranean pinewoods in the area. On the other hand, the charcoal assemblage of Pintia reveals a more important presence of the current Mediterranean highland pines in the lowlands of the Central Iberian Peninsula in the late-Holocene suggesting the existence of interglacial refugia. Finally, this work highlights palaeoecological studies as valuable tools to support decisions on forest management related to conservation and restoration of our natural heritage.  相似文献   
45.
随着环境保护、经济社会可持续发展等相关立法力度的加大,渔船尾气排放问题逐渐引起管理层和业界的广泛关注。对湖南、江西2省3个地区(岳阳、沅江和上饶)进行走访调研;同时携带烟气测试仪对其捕捞作业渔船进行现场检测,其中实际检测9艘,木质的8艘,钢质的1艘,船长都在12 m及以下,总功率都小于44.1kW;并按照规范现场获取油样,共取得有效样本9份,通过专业运输公司寄送至国家专业油样分析机构进行检测分析。结果显示:在高速和低速两种工况下,9条船中,有3艘渔船在低速航行条件下,CO排放指标未达到第三阶段排放标准(小于5.5 g/kWh),其他均达到,达到率83.3%;按照GB252—2015普通柴油分类要求,所有油样样品都达到要求,合格率为100%。研究表明:我国内陆渔船尾气排放量总体影响较小;排放量与柴油机使用年限相关性不大;须提高燃油品质、减少污染物排放;应加强渔船尾气后处理系统的开发应用等。内陆捕捞作业渔船尾气排放总体情况较好,但仍有进一步提升的空间。  相似文献   
46.
晋南盐水水域生物资源调查   总被引:7,自引:4,他引:7  
  相似文献   
47.
刘延明  陆克芬  方崇 《安徽农业科学》2009,37(26):12670-12672
针对目前我国城市内河普遍遭到污染的问题,在分析影响内河水质因素的基础上,选取BOD5(五日生化需氧量)、CODCr(化学需氧量)、石油类、挥发酚、NH3-N(氨氮)和总磷等6个主要因素作为评价因子,建立了城市内河水质评价的投影寻踪分析模型,采用粒子群算法对该评价模型进行优化,并将其应用于南宁市10条内河水质的评价与排序。研究表明:用投影寻踪回归分析法进行水质评价,避免了传统评价方法由于主观原因造成的误差,方法简单、评价结果合理可信,为我国城市内河水质的评价提供了新途径。  相似文献   
48.
利用元素分析仪测定了河西走廊不同地区盐碱土壤的碳、氮、氢含量,研究了其分布特征.结果表明,河西走廊内陆河不同流域地区盐碱土壤中的碳、氮、氢分布呈现出显著的地域特点.尤其是疏勒河流域,其碳、氮、氢总含量明显高于其它两个地区(黑河流域、石羊河流域),沿河西走廊从西向东,土壤中碳、氮、氢的总含量依次降低,土壤的肥沃程度也沿河...  相似文献   
49.
The Japanese sand lance (Ammodytes personatus) population in the Seto Inland Sea shows large fluctuations every few years. Its recruitment to the fishery resources is much more dependent on the survival rate of 0-age fish than is the case for other fish species because 0-age fish directly recruit to next-year spawning adults. Since the 0-age fish population depends on its larval population, which is easily influenced by natural and human impacts, high larval mortality due to predation by adults and high dispersion of larvae by wind-driven currents from spawning grounds to other locations can have very important effects on stock fluctuations. A numerical model of population dynamics of the sand lance in the eastern Seto Inland Sea was developed that focuses on wind-induced transport and adult predation of the larvae. The model successfully simulated the two-year periodic fluctuation and was consistent with actual fluctuations in fishery catches. It suggests that the various coefficients given in the model are appropriate to explain the actual population dynamics of the sand lance. The model shows that adult predation on the larvae plays a very important role in the two-year periodic fluctuation, and the maximum predation rate is estimated to be ten individuals per day. Wind-induced transport modifies the impact of this predation. Variances in the two-year periodic fluctuation become smaller with weaker westerly wind velocity. The appropriate transport rates from Bisan Strait and the Harima-nada Sea are estimated to be 0.04 d-1 and 0.01 d-1, respectively.  相似文献   
50.
ABSTRACT:   The occurrence and distribution of larval and juvenile Japanese flounder Paralichthys olivaceus and major demersal fish from May to September were examined at seven sandy beaches at the central Seto Inland Sea. The flounder appeared from late May to August and were mainly collected at a depth of 2–5 m. Settlement of larval flounder was seen from late May to late June. A total of 6412 individuals of 17 species representing 12 families were collected in the study area. The dominant fish species were Favonigobius gymnauchen (56.0%), Tarphops oligolepis (8.1%), Rudarius ercodes (7.8%), P. olivaceus (7.3%), Repomucenus spp. (7.0%) and Heteromycteris japonica (3.3%). The catches of flounder differed among beaches and months. The number of flounder in June at Ohama Beach, where the most flounder were collected, was 22.6 individuals per haul (400 m2). The density of the flounder correlated negatively to that of F. gymnauchen .  相似文献   
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