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41.
CM Lucci LL Schreier GM Machado CA Amorim SN Báo JR Dobrinsky 《Reproduction in domestic animals》2007,42(1):76-82
The purpose of this study was to evaluate the effect of cooling ovarian tissue on pig pre-antral follicles. Ovaries were maintained in saline solution (0.9%) at 4 or 20 degrees C for 6, 12 or 18 h. After storage, pre-antral follicles were morphologically evaluated. While primordial follicles were not affected by the storage, the percentage of morphologically normal growing follicles was significantly reduced in ovarian tissue stored at 20 degrees C for 12 or 18 h. To test the viability of stored follicles, growing follicles isolated from ovaries stored at 4 degrees C for 18 h and at 20 degrees C for 6 h were cultured for 3 days. Follicles stored in either condition presented the same growth pattern in vitro as fresh follicles. We conclude that storage of pig ovaries at 4 degrees C for up to 18 h or at 20 degrees C for up to 6 h does not affect the morphology of growing follicles or their ability to grow in vitro. 相似文献
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There is a growing need for both science and practice domains to collaboratively and systematically seek knowledge-based strategies for sustainable development.In recent years,transdisciplinary research has emerged as a new approach that enables joint problem solving among scientists and stakeholders in various fields. In this paper,we aim to introduce transdisciplinary research for supporting the integration of the concept of ecosystem services into land and water management in the Tarim River Basin,Xinjiang,Northwest China.While a large number of ecosystem service studies have helped to raise the awareness for the value of nature in China,a number of challenges remain,including an improved understanding of the relationships between ecosystem structure, functions and services,and the interaction of the various ecosystem services.A meaningful valuation of ecosystem services also requires the consideration of their strong spatial heterogeneity.In addition,ways to introduce the concept of ecosystem services into decision-making in China need to be explored.Thus,successful integration of the concept of ecosystem services into actual land and water management requires a broad knowledge base that only a number of scientific disciplines and stakeholders can provide jointly,via a transdisciplinary research process.We regard transdisciplinary research as a recursive process to support adaptive management that includes joint knowledge generation and integration among scientists and stakeholders.System,target,and transformation knowledge are generated and integrated during the process of(1)problem(re)definition,(2)problem analysis and strategy development,and(3)evaluation of the impact of the derived strategy.Methods to support transdisciplinary research comprise participatory modelling(actor-based modelling and Bayesian Networks modelling)and participatory scenario development.Actor-based modelling is a semi-quantitative method that is based on the analysis of problem perspectives of individual stakeholders as depicted in perception graphs.With Bayesian Networks,complex problem fields are modelled probabilistically in a simplified manner,using both quantitative data and qualitative expert judgments.These participatory methods serve to integrate diverse scientific and stakeholder knowledge and to support the generation of actually implementable management strategies for sustainable development.For the purpose of integrating ecosystem services in land and water management in the Tarim River Basin through transdisciplinary research,collaboration among scientists and institutional stakeholders from different sectors including water,agriculture,forestry,and nature conservation is required.The challenge is to adapt methods of transdisciplinary research to socio-cultural conditions in China,particularly regarding ways of communication and decision-making. 相似文献
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LILJA STEFANSDOTTIR JÓN SOLMUNDSSON GUÐRÚN MARTEINSDOTTIR KRISTJÁN KRISTINSSON JÓNAS PÁLL JONASSON 《Fisheries Oceanography》2010,19(1):42-62
Elevated ocean temperatures have been predicted to lead to a poleward shift in the latitudinal distribution ranges of fish species. Different responses of fish species to increased temperatures might lead to changes in assemblage structure and local species richness. In this study, the assemblage structure and diversity of groundfish in Icelandic waters were examined using data from a standardized groundfish survey conducted annually in 1996–2007. We used hierarchical cluster analysis to define assemblages in two time periods and canonical correspondence analysis to explore the relationships between the assemblages and temperature, depth, latitude, longitude and year. We further used two estimates of diversity, species richness and the Shannon index. Four major species assemblages were identified. Assemblages in the hydrographically stable deep waters north of the country were consistent during the study, while assemblage structure in the more variable shallow waters underwent some changes. For this period of generally increasing sea temperature, the canonical correspondence analysis also revealed a shift towards species representative of warmer temperatures. Diversity was shown to be highly variable both temporally and spatially, and also to vary with depth and temperature. Species richness increased with temperature and time southwest of the country, but decreased northeast of the country. The different trends detected between the northern and southern areas illustrate the importance of performing analyses at the most appropriate scale. 相似文献
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Water, Air, & Soil Pollution - Basic activated sludge process kinetics of: (1) complete-mix reactor without sludge recycle; (2) complete-mix reactor with sludge recycle; and (3) plug-flow... 相似文献
48.
Jessie P.H. Poon 《Growth and change》2003,34(2):135-156
Abstract The dramatic evolution of global finance in the last three decades has seen intensified competition among the world's major cities to become prominent control centers of global financial flows. This paper examines the spatial organization and evolution of capital markets in forty‐three world cities from 1980 to 1998. It finds evidence of the strengthening of hierarchical tendencies among world financial and capital cities as they search for ways to differentiate between themselves through financial concentration and productivity. The results also indicate a trend towards the dominance of London and New York in this financial hierarchy, and that top tier cities tend to be characterized by significantly lower levels of market and share concentrations, share trading value, and risks. Finally, important differences in ownership patterns between the capital markets are detected for the top cities of the hierarchy. 相似文献
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The authenticity of weed distribution maps prepared by the geostatistical estimation method, kriging, was investigated. We concentrated on the total number of weed plants and the dominant weed genus Veronica spp. in a 2.1-ha field of winter wheat. Different sampling distances were evaluated. Our analyses showed that kriging weed densities based on seedling counts collected in, 0.25.m2 circles in a sampling grid of approximately 10 m × 10 m gave good agreement with actual observations. Reducing the sampling grid to 20 m × 30 m gave poor agreement. New sampling methods combined with positioning devices and injection sprayers are discussed with reference to site-specific weed management. 相似文献
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