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181.
Church forests collectively represent the only surviving remnants of the original montane forest, serving as critical sanctuaries for many of Ethiopia's endangered and endemic plant and invertebrate taxa. Modern inventories of church forests suggest that they are vulnerable to degradation because of their small size and isolation. The aim of this study is to use historical air photos from the period of the Italian occupation of Ethiopia (1935–1941) to measure changes to church forests over a ~80‐year time span. We find little evidence that church forests in the study region around Debra Tabor in the northern Ethiopia highlands are declining in size. Rather, church forests have proven to be remarkably resilient on the landscape despite decades of dramatic change to the world around them. Our findings, therefore, highlight the effectiveness of religion‐based forest stewardship. Results also indicate, however, that while many church forests used to be buffered from intensive agricultural activity (e.g., cultivation and pasture) today, they find themselves significantly more isolated and vulnerable to edge effects as a result of a general decrease of trees and bushlands surrounding the forests. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
182.
Aleutian disease (AD), caused by the Aleutian mink disease virus (AMDV), is a major health concern that results in global economic losses to the mink industry. The unsatisfactory outcome of the culling strategy, immunoprophylaxis, and medical treatment in controlling AD have urged mink farmers to select AD resilient mink based on several detection tests, including enzyme-linked immunosorbent assay (ELISA), counterimmunoelectrophoresis (CIEP), and iodine agglutination test (IAT). However, the genetic analysis of these AD tests and their correlations with pelt quality, reproductive performance, packed-cell volume (PCV), and harvest length (HL) have not been investigated. In this study, data on 5,824 mink were used to estimate the genetic and phenotypic parameters of four AD tests, including two systems of ELISA, CIEP, and IAT, and their genetic and phenotypic correlations with two pelt quality, five female reproductive performance, PCV, and HL traits. Significances (P < 0.05) of fixed effects (sex, year, dam age, and color type), covariates (age at harvest and blood sampling), and random effects (additive genetic, permanent environmental, and maternal effects) were determined under univariate models using ASReml 4.1 software. The genetic and phenotypic parameters for all traits were estimated under bivariate models using ASReml 4.1 software. Estimated heritabilities (±SE) were 0.39 ± 0.06, 0.61 ± 0.07, 0.11 ± 0.07, and 0.26 ± 0.05 for AMDV antigen-based ELISA (ELISA-G), AMDV capsid protein-based ELISA, CIEP, and IAT, respectively. The ELISA-G also showed a moderate repeatability (0.58 ± 0.04) and had significant negative genetic correlations (±SE) with reproductive performance traits (from −0.41 ± 0.16 to −0.49 ± 0.12), PCV (−0.53 ± 0.09), and HL (−0.45 ± 0.16). These results indicated that ELISA-G had the potential to be applied as an indicator trait for genetic selection of AD resilient mink in AD endemic ranches and therefore help mink farmers to reduce the adverse effects caused by AD.  相似文献   
183.
New concepts have emerged in theoretical ecology with the intent to quantify complexities in ecological change that are unaccounted for in state-and-transition models and to provide applied ecologists with statistical early warning metrics able to predict and prevent state transitions. With its rich history of furthering ecological theory and its robust and broad-scale monitoring frameworks, the rangeland discipline is poised to empirically assess these newly proposed ideas while also serving as early adopters of novel statistical metrics that provide advanced warning of a pending shift to an alternative ecological regime. We review multivariate early warning and regime shift detection metrics, identify situations where various metrics will be most useful for rangeland science, and then highlight known shortcomings. Our review of a suite of multivariate-based regime shift/early warning indicators provides a broad range of metrics applicable to a wide variety of data types or contexts, from situations where a great deal is known about the key system drivers and a regime shift is hypothesized a priori, to situations where the key drivers and the possibility of a regime shift are both unknown. These metrics can be used to answer ecological state-and-transition questions, inform policymakers, and provide quantitative decision-making tools for managers.  相似文献   
184.
利用云贵高原2000年、2010年和2018年的遥感影像及气象数据,并结合生态系统弹性力计算方法,对云贵高原生态系统弹性力进行计算,分析了云贵高原25个市生态系统弹性力的时空分布特征,同时对其变化的主要影响因素进行探究。结果表明:云贵高原生态系统弹性力在研究期内呈现逐年增加趋势;在空间上,云贵高原生态系统弹性力分布为西南高、西北低、中部局部较低,东部较高。将生态系统弹性力分为4个等级,其中较弱和中等等级面积占比呈减少趋势,较强和很强等级面积占比逐年增加。驱动因子分析表明,降雨和气温是影响生态系统弹性力空间分布变化的主要因素。研究结果可对云贵高原生态系统保护提供一定的科学依据。  相似文献   
185.
186.
为探究乡村数字化对农业韧性的影响,利用2011—2020年中国30个省(直辖市、自治区)的面板数据(统计数据未含西藏及港澳台地区,下同),采用熵值法测算了中国农业韧性与乡村数字化发展水平。利用耦合协调度模型、中介效应模型分析了二者的协调程度,探究了乡村数字化对农业韧性的作用机制。结果表明:当前我国农业韧性水平与乡村数字化发展水平及二者的耦合协调程度总体呈上升趋势;乡村数字化可通过缩小城乡收入差距、提升农村人力资本水平促进农业韧性提高;乡村数字化在农业韧性水平低的地区提升效应更加明显。  相似文献   
187.
Climate change education (CCE) can be an important tool to increase local community resilience. In 2017, the Pacific Community ratified the Framework for Resilient Development in the Pacific (FRDP) aiming to equip local communities with skills needed to become more climate change resilient. In 2018, Fiji implemented the Climate Change Resilience Programme (CCRP) at the University of the South Pacific (USP), the first of its kind in the South Pacific. This paper evaluates (i) the orientation and aim of the programme and (ii) how different stakeholders influenced the curriculum development process. Tribe's concept of curriculum space is used to highlight the overall aim of the CCRP. Freeman's stakeholder theory allows to identify key stakeholders and their influence on the curriculum. Results indicate that the programme seems to foster climate resilience in the workplace rather than the local community. Unfortunately, current and future community leaders, the notional targets of this course, were almost completely unrepresented in the process to accredit the course, with the body responsible for accreditation being dominated by industry representatives. This study helps to inform the current review of the Regional Certificate Programme to realign it with its initially envisioned community focus.  相似文献   
188.
Summary Using gene-for-gene relationships as a basis for comparison, I show that Robinson's (1979, 1980) concept of an evolutionarily stable strategy, or ESS for short, is very different from the original definition of Maynard Smith & Price (1973) and, in fact, contradicts it in a number of important respects. The notion of an evolutionarily persistent strategy, or EPS for short, is introduced to clarify these differences and to reduce the potential for confusion in the future. The EPS concept is developed in terms of Holling's (1973) concept of resilience and Van Valen's (1976) notion of expansive energy. The combination of an ESS (sensu Maynard Smith & Price, 1973) and an EPS is offered as an alternative to Robinson's (1979, 1980) ESS concept. Robinson's recommendations for a holistic approach to plant pathosystem management are supported.  相似文献   
189.
J Pino  X Arnan  A Rodrigo  J Retana 《Weed Research》2013,53(6):470-478
This work explored the invasion patterns of Conyza species in Mediterranean pine forests after fire and identified their main correlates through a temporal study approach. We hypothesised that wildfires might favour Conyza spp. invasion in these forests, but only transiently and depending on fire regime. We recorded Conyza spp. invasion and subsequent extinction in plots from species' occurrence and cover in vegetation surveys. We also explored the association of Conyza spp. presence and cover with a set of climatic, landscape and local (plot) factors using GLZ and GLM. We assessed changes in significant factors over time with a Wilcoxon test for paired samples. Evidence for Conyza spp. establishment was found in two‐thirds of the study plots, with an invasion peak 2 years after fire. Local factors related to resource availability, including high fire severity, low soil stoniness and total vegetation cover and high herbaceous cover, were significantly correlated with Conyza occurrence in plots at the invasion peak. However, Conyza cover was always low (≤6%) and populations did not persist more than several years, thus becoming rarer as plant cover increased. Landscape and climatic factors showed no association with Conyza occurrence. In conclusion, wildfires favour transient invasion of European Mediterranean pine forests by Conyza spp. Invasion is mostly enhanced by local fire severity and constrained by subsequent vegetation recovery, while it is poorly explained by climate and landscape, either current or historical.  相似文献   
190.
马晓倩 《安徽农业科学》2013,(23):9800-9803
以甘肃省榆中县北部山区为研究区域,通过实地调研和问卷访谈,从收入多样性角度分析了农户干旱恢复力,并进一步探讨了不同农户类型之间干旱恢复力的差异.研究表明,导致农户干旱恢复力存在显著差异的主要原因是农民的收入多样性差异,还有该地区地势东高西低、农户旱灾意识、防旱措施等多种原因;收入多样性差异导致兼业型农户干旱恢复力最高,其次是非农业类型,最后为纯农业类型.研究结果对其他干旱地区提升应对自然灾害的恢复能力有借鉴意义.  相似文献   
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