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Sparse coding presents practical advantages for sensory representations and memory storage. In the insect olfactory system, the representation of general odors is dense in the antennal lobes but sparse in the mushroom bodies, only one synapse downstream. In locusts, this transformation relies on the oscillatory structure of antennal lobe output, feed-forward inhibitory circuits, intrinsic properties of mushroom body neurons, and connectivity between antennal lobe and mushroom bodies. Here we show the existence of a normalizing negative-feedback loop within the mushroom body to maintain sparse output over a wide range of input conditions. This loop consists of an identifiable "giant" nonspiking inhibitory interneuron with ubiquitous connectivity and graded release properties. 相似文献
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Huot I Paradis G Receveur O Ledoux M;Quebec Heart Health Demonstration Project Research Group 《Public health nutrition》2004,7(8):1009-1016
OBJECTIVE: To determine the correlates of a high-fat diet in urban, suburban and rural areas of Quebec, Canada. DESIGN: A secondary analysis of data collected as part of a 5-year multi-factorial, multi-setting, community-intervention project. SETTING: Urban, suburban and rural settings of the province of Quebec, 1997. SUBJECTS: Data were analysed from a sample of 5214 participants (2227 males, 2987 females). A food-frequency questionnaire was completed and a global index of food quality was calculated. Logistic regression was used to identify correlates of a diet high in total fats, saturated fat and cholesterol. RESULTS: In both genders, lower level of education, smoking status, French and English languages compared with other languages spoken at home, and a rural environment were associated with poor diet quality. Having no intention to eat low-fat dairy products more often was associated with a high-fat diet. In men, obesity (body mass index >/=30 kg m(-2)) and absence of reported health problems were correlates of a high-fat diet, while, in women, lower physical activity was a correlate. CONCLUSIONS: Future health interventions in Quebec should target people with low education, smokers and those living in a rural environment. Obese men and sedentary women should have access to specific dietetic resources. 相似文献
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Summary A sample of 50 wild populations of perennial ryegrass (12 from northern Italy and 38 from Corsica) was tested with controls as spaced plant nurseries in two locations in France. Multivariate analyses, such as principal component analysis, hierarchical clustering and factorial discriminant analysis were used to describe the genetic variability of such Mediterranean material.On the whole, Mediterranean populations do not appear to be more promosing than the north European varieties. However, some populations from Corsica could be used to develop genetic resources for the Mediterranean area.The interest of each cluster is discussed and geographical repartition of clusters is shown on country maps.The factorial discriminant analysis gives a linear discriminant Fisher function which clearely discriminates two groups of populations according to their country of origin. 相似文献
116.
Summary Experiments to assess variation in the resistance of winter wheat to infection by Microdochium nivale were conducted over two consecutive years. Resistance was evaluated using an agar disk technique to reproduce stem lesions and by spraying a conidial suspension to reproduce head blight symptoms. Significant variation for stem reaction measured as stem lesion area (SLA), and head reaction measured as disease severity (DS) was found in the 33 winter wheat genotypes tested. Data obtained over two years in controlled environment conditions were significantly correlated (r=0.713 for SLA and r=0.738 for DS), whereas field data showed a significant genotype x year interaction for disease severity. Quantitative variation for susceptibility to stem and head infection by M. nivale was found among the 33 genotypes tested. The majority of genotypes expressed moderate susceptibility, with cultivar Goupil being very susceptible to both stem and head infection, and the remainder, Renan, Arminda, Munstertaler and Saint-Johann were the most resistant. Resistance to stem and head to M. nivale were not correlated (r=0.358). 相似文献
117.
IBD-based QTL detection in inbred pedigrees: A case study of cereal breeding programs 总被引:2,自引:0,他引:2
Mapping quantitative trait loci in plants is usually conducted using a population derived from a cross between two lines.
The power of such QTL detection and mapping strategies and the estimation of the effects highly depend on the choice of the
two parental lines. Thus, the QTL detected in such populations only represent a small part of the genetic architecture of
the trait. Besides, the effects of only two alleles are characterized, which is of limited interest to the breeder. On the
other hand, common pedigree breeding material remains unexploited for QTL mapping. From a pre-breeding perspective, the utilization
of the good quality phenotypic data generated by breeders can be improved through the search and manipulation of QTL. The
development of statistical techniques suitable for QTL mapping in general conventional breeding populations is thus challenging.
In this study, we extend QTL mapping methodology to a generalized framework, based on a two-step IBD variance component approach,
applicable to any type of breeding population coming from inbred parents. The proposed developments attempt to make full use
of any inferable relatedness information between the parents. The power and accuracy of this method were assessed on simulated
data mimicking conventional breeding programs in cereals, in an effort to reproduce actual conditions of marker and gene allelic
frequencies across the parental lines. A wide range of breeding scenarios and of genetic architectures was explored. We demonstrated
that taking into account the estimable relatedness between the parents significantly improved the power and accuracy of the
QTL parameter estimations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
118.
Rondelaud D Hourdin P Vignoles P Dreyfuss G Cabaret J 《Veterinary parasitology》2011,181(2-4):166-173
Field investigations in 361 liver fluke infected cattle- or sheep-breeding farms on acid soil were carried out during thirty years in March and April to record indicator plants in relation to the category of site colonized by the intermediate host of liver fluke, the snail Galba truncatula. Seven types of snail zones and six species of indicator plants were recorded in the 7709 positive sites studied. The most frequent habitats were located at the peripheral extremities of open drainage furrows. Juncus acutiflorus, Juncus effusus, Glyceria fluitans, and Agrostis stolonifera were the indicator plants. Plant indicators were highly efficient (38-80% of variance explained) when used with the size of site area within a hydrographical zone. The identification of positive sites for G. truncatula is a key for controlling the intermediate host on pastures through biological control with predatory molluscs. The positive sites may be detected using a two-step method including first categorization of hydrographical zones and then, within a zone, use of one or several indicator plants (frequently J. acutiflorus). 相似文献
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