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1.
  1. Mediterranean fin whales aggregating in the Pelagos Sanctuary in summer to feed are exposed to vessel collision risk, particularly from high-speed ferries.
  2. This study developed models to predict summer fin whale distribution using a generalized additive model (GAM) and MaxEnt, with the aim of providing a tool to identify potential high whale–ferry collision risk areas along ferry routes within the Pelagos Sanctuary during summertime.
  3. Models were trained using sightings data collected in the summer months of 2009–2018 on board ferries crossing the central area of the Pelagos Sanctuary. Environmental predictors were bathymetry and mean sea surface chlorophyll concentration of the annual spring bloom period.
  4. The predictive ability of GAM and MaxEnt was assessed using existing knowledge of summer fin whale distribution in the region. GAM (deviance explained = 20.2%) predictions matched documented distributions more closely than that of MaxEnt, with highest predicted fin whale occurrence in deep offshore waters (>2000 m) encompassing the central north-western and western regions, and in the south-eastern region, consistent with known fin whale habitats within the Pelagos Sanctuary. Inter-annual variability was evident, influencing collision risk areas.
  5. Collision risk was estimated as a function of the overlap between the predicted probability of fin whale occurrence and ferry density estimated from Automated Identification System data. Ferry routes that cross the northern and eastern regions of the Pelagos Sanctuary presented relatively higher collision risk.
  6. Areas with changes in risk intensity between the years were temporally and spatially dynamic: some appeared intermittently throughout the study period while others persisted over consecutive years or recurred in different years.
  7. Due to the vastness of the Pelagos Sanctuary, vessel speed reduction maybe a more practical measure to manage collision risk than re-routing shipping lanes. A combination of Seasonal Management Areas and Dynamic Management Areas approaches could be adopted for high-risk areas.
  相似文献   
2.
王春晓  高峰  陈富桥  曾亮 《茶叶科学》2021,41(6):865-875
“一带一路”倡议是促进中国茶叶出口的重大机遇,但是现有研究缺乏对其实际效果的系统评估。基于2009—2018年中国与40个主要茶叶进口国家和地区的面板数据,运用渐进双重差分模型评估了“一带一路”倡议对中国茶叶出口增长的政策影响。结果表明,在控制其他影响变量的条件下,“一带一路”倡议对于中国茶叶整体出口额增长具有一定的正向影响;进一步的产品异质性分析表明,“一带一路”倡议显著促进了中国绿茶出口的增长,但对红茶出口的作用尚不显著。此外,在控制变量中,国家和地区的人均GDP以及经济开放水平的提高也能够显著促进中国茶叶出口增长。最后对我国茶叶出口贸易如何把握“一带一路”政策机遇提出了对策建议。  相似文献   
3.
研究了数论函数方程S(SL(n~(11)))=φ_2(n)及S(SL(n~(12)))=φ_2(n)的可解性问题,其中S(n)为Smarandache函数,SL(n)为Smarandache LCM函数,φ_2(n)为广义欧拉函数.利用初等数论的内容方法及计算技巧得到上述两个数论函数方程的所有正整数解.  相似文献   
4.
Invasive grasses (especially Setaria pumila (Poir.) Roem. et Schult) increasingly threaten meadows and pastures as a consequence of human impact and climate change. We conducted a study in 2012 and in 2013 to better understand the growing cycle and the influence of S. pumila on forage quality of lowland meadows. We observed a rapid increase of S. pumila presence and phytomass on the southern side of the Alps across the growing season. We measured (i) above‐ground phytomass, with a modified Corral‐Fenlon method; (ii) botanical composition using the linear point quadrat method; and (iii) grassland chemical composition by NIRs (near‐infrared spectroscopy) analyses. To test the hypothesis that S. pumila summer growth is related to specific climatic conditions, meteorological data (temperature, precipitation and evapotranspiration) were collected from meteorological stations near the study sites. Total phytomass was sorted into S. pumila and other species. We used a generalized linear mixed models (GLMM) and found the abundance of S. pumila to be inversely correlated with rainfall and the presence of other species, but positively correlated with temperature increase. The increase of S. pumila above‐ground phytomass production was linked to a reduction of forage quality.  相似文献   
5.
  1. A large‐scale assessment of the summertime suitable habitat for Delphinus delphis (short‐beaked common dolphin) and Tursiops truncatus (common bottlenose dolphin) in Greek Seas (Eastern Mediterranean) was conducted using data from dedicated and opportunistic cetacean surveys and published data records.
  2. Using a presence/absence approach, generalized additive models were applied to define a suite of environmental, bathymetric and biotic factors that best describe common and bottlenose dolphin spatial distribution, during early (May, June, July) and late (August, September) summer.
  3. A geographic information system (GIS) was used to integrate sightings data with environmental characteristics, distance from the coast and sardine probability of presence. These variables were considered as good proxies for defining species‐suitable habitat within the study area's coastal environment.
  4. The final selected models were used to produce annual probability maps of the presence of the species in the entire Greek Seas, as a measure of habitat suitability. Based on the mean probability and standard deviation maps for the study period GIS techniques were subsequently used to determine the persistent (areas with high mean and low variation) and occasional (high mean and high variation) habitat of each species.
  5. Results showed that there was a high probability of common dolphin presence in areas with a high probability of sardine presence. For bottlenose dolphin, higher probability of the presence of species occurred in areas closer to the shore, with a high probability of sardine presence and with high concentrations of chlorophyll‐a.
  6. In both seasons, the North Aegean Sea and the Inner Ionian Sea Archipelago were indicated as the most suitable areas for common dolphin distribution. Persistent habitat areas of the bottlenose dolphin included enclosed seas, continental shelf waters, and waters surrounding islands. The indicated suitable areas are discussed along with deficiencies of the models and future implications for conservation.
Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
6.
Growth data of two different commercial turbot (Scophthalmus maximus) strains reared in recirculating aquaculture systems were analysed with the aim to determine the most suitable model for turbot. To assess the model performance three different criteria were used: (1) The mean percentage deviation between the estimated length and actual length; (2) the residual standard error with corresponding degrees of freedom and (3) the Akaike information criterion. The analyses were carried out for each strain separately, for sexes within strains and for a pooled data set containing both strains and sexes. We tested a pre‐selection of six models, containing three to four parameters. Models were of monomolecular shape or sigmoid shape with a flexible point of inflection including the special case of monomolecular shape in defined cases of their parameters. The 4‐parametric Schnute model achieved best fit in 62% of all cases and criteria tested, followed by the also 4‐parametric generalized Michaelis–Menten equation in 48% and the 4‐parametric Janoschek model (38%). The von Bertalanffy growth function achieved only 29%, Brody 24% and a new flexible function 19% best fit. In a 1–1000 day growth‐simulation sigmoid shaped curves were produced by the Schnute model in 71% of cases. The Janoschek and the Michaelis–Menten model each produced sigmoid curves in 57% of all cases. This indicates that a flexible 4‐parametric function reflects the growth curve of turbot the best and that this curve is rather sigmoid than monomolecular shaped.  相似文献   
7.
采用广义回归神经网络建立酪蛋白乳化性与疏水性关系   总被引:2,自引:1,他引:1  
为了研究琥珀酰化修饰后酪蛋白乳化性与疏水性关系,该文以琥珀酰化牦牛乳酪蛋白为研究对象,分析了不同酰化程度酪蛋白乳化性及疏水性变化趋势,采用广义回归神经网络建立了牦牛乳酰化酪蛋白乳化性与疏水性关系模型。结果显示,琥珀酰化牦牛乳酪蛋白乳化性和疏水性均与酰化程度、pH值有关,pH值为5以上,随着酰化程度的增加,酪蛋白乳化活性增大;等电点附近,酪蛋白乳化活性较差,等电点之后乳化活性迅速增大。pH值介于2-6时,所有酪蛋白乳化稳定性较强,pH值介于6-11之间时,酪蛋白乳化稳定性差异较小,pH值为12时乳化稳定性有所增加。酪蛋白内荧光与1-苯胺基萘-8-磺酸(1-aniline napthalene-8-sulfonic acid,ANS)外源荧光最大荧光强度和最大发射波长随酰化程度及pH值变化表现出较为复杂的关系。通过广义回归神经网络(generalized-regression-neu-network,GRNN)建立了牦牛乳酪蛋白疏水性参数、pH值、酰化程度与乳化性关系,网络模型对乳化性的预测相对误差小于10%,预测结果良好。研究结果为酪蛋白乳化性研究提供了参考依据。  相似文献   
8.
Spatial and temporal trends of sailfish catch rates in the southwestern and equatorial Atlantic Ocean in relation to environmental variables were investigated using generalized additive models and fishery‐dependent data. Two generalized additive models were fit: (i) ‘spatio‐temporal’, including only latitude, longitude, month, and year; and (ii) ‘oceanographic’, including sea surface temperature (SST), chlorophyll‐a concentration, wind velocity, bottom depth, and depth of mixed layer and year. The spatio‐temporal model explained more (average ~40%) of the variability in catch rates than the oceanographic model (average ~30%). Modeled catch rate predictions showed that sailfish tend to aggregate off the southeast coast of Brazil during the peak of the spawning season (November to February). Sailfish also seem to aggregate for feeding in two different areas, one located in the mid‐west Atlantic to the south of ~15°S and another area off the north coast of Brazil. The oceanographic model revealed that wind velocity and chlorophyll‐a concentration were the most important variables describing catch rate variability. The results presented herein may help to understand sailfish movements in the Atlantic Ocean and the relationship of these movements with environmental effects.  相似文献   
9.
Stem analysis data of 432 trees were obtained from even-aged, pure natural stands of Calabrian pine in the central Mediterranean Region of Turkey. Eight dynamic site equations derived with the Generalized Algebraic Difference Approach (GADA) were compared, based on autoregressive analysis and a thorough evaluation of the goodness of fit. We used generalized nonlinear least squares methods for model fitting. The adjusted coefficients of determination (0.9825–0.9842), root-mean-square errors (0.8004–0.8435 m), and Akaike’s information criterion differences (0–145) indicated a good fit of the eight site index equations. The Hossfeld equation (M3) provided the best result. The Durbin-Watson test statistic did not reveal an autocorrelation issue while the Hossfeld equation provided a satisfactory solution to the serial correlation problem in stem analysis data as time series using autoregressive modeling. This study presents new site index models for Calabrian pine forests in the central Mediterranean region of Turkey where it is the most important commercial tree species. The site index equation, based on the Hossfeld model is recommended for height growth prediction and site classification of Calabrian pine stands in the central Mediterranean region of Turkey, providing a new basis for growth prediction and yield estimation in these important forest ecosystems.  相似文献   
10.
Striped marlin (Kajikia audax) is an epipelagic fish distributed in oceanic and coastal waters of the Pacific Ocean. This species is usually found in warm and coastal waters with high primary productivity. The main goal of this study was to describe the spatial segregation of striped marlin by average Eye‐Fork length (EFL) in the eastern Pacific Ocean (EPO) and its relationship with environmental variables using EFL data obtained from tuna purse‐seining and Generalized Additive Models (GAMs). The model suggested that larger individuals of striped marlin were more likely to be found in waters with high Chlorophyll‐a concentration (>2 mg/m3) and with temperatures lower than 25°C, within a region known as the “cold tongue” and the Humboldt current system, while smaller individuals were more likely to be found in warmer and low productive areas within a region known as the “warm pool of the EPO.” We observed that set type caused a large variation on average EFL of striped marlin; larger fish were captured in sets associated with floating objects (natural and manmade), while smaller fish were captured in sets associated with dolphins. Despite this, our findings suggest that striped marlin has a latitudinal gradient in average EFL; larger individuals occurred predominantly south of 10°N, while smaller ones occurred predominantly in coastal waters between 10°N and 20°N, thus demonstrating a spatial segregation of the species affected by its maturity stage.  相似文献   
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