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71.
Vianey Leos-Barajas Eric J. Gangloff Timo Adam Roland Langrock Floris M. van Beest Jacob Nabe-Nielsen Juan M. Morales 《Journal of Agricultural, Biological & Environmental Statistics》2017,22(3):232-248
Hidden Markov models (HMMs) are commonly used to model animal movement data and infer aspects of animal behavior. An HMM assumes that each data point from a time series of observations stems from one of N possible states. The states are loosely connected to behavioral modes that manifest themselves at the temporal resolution at which observations are made. Due to advances in tag technology and tracking with digital video recordings, data can be collected at increasingly fine temporal resolutions. Yet, inferences at time scales cruder than those at which data are collected and, which correspond to larger-scale behavioral processes, are not yet answered via HMMs. We include additional hierarchical structures to the basic HMM framework, incorporating multiple Markov chains at various time scales. The hierarchically structured HMMs allow for behavioral inferences at multiple time scales and can also serve as a means to avoid coarsening data. Our proposed framework is one of the first that models animal behavior simultaneously at multiple time scales, opening new possibilities in the area of animal movement and behavior modeling. We illustrate the application of hierarchically structured HMMs in two real-data examples: (i) vertical movements of harbor porpoises observed in the field, and (ii) garter snake movement data collected as part of an experimental design. Supplementary materials accompanying this paper appear online. 相似文献
72.
Mevin B. Hooten Ruth King Roland Langrock 《Journal of Agricultural, Biological & Environmental Statistics》2017,22(3):224-231
In this introduction, we provide a brief overview to statistical models for animal trajectories and then summarize the set of invited articles that comprise the issue. 相似文献
73.
Xavier Harmon Christopher N. Boyer C. Owen Gwathmey James A. Larson Roland K. Roberts 《Journal of plant nutrition》2017,40(11):1547-1556
Recent research has shown that stochastic yield response functions fit data better than deterministic yield response functions; however, little research exists comparing profit-maximizing fertilizer rates for upland cotton (Gossypium hirsutum L.) using stochastic and deterministic yield response functions. The objective of this research was to determine the most appropriate yield response functional form from which to determine the profit-maximizing potassium (K) rate for cotton in Tennessee. Data were used from a nine-year K fertilizer experiment in Jackson, Tennessee. Quadratic, quadratic-plus-plateau, linear response plateau, and linear response stochastic plateau response functions were estimated to determine the yield response function that best fit the data. The linear response stochastic plateau function was the most suitable yield response function for the data. The profit-maximizing K rate ranged from 65.2 to 74.3 kg K ha?1. Misspecification of the yield response function recommended over-application of K fertilizer and decreased the producer's short-term profits. 相似文献
74.
Fekadu Marame Chemeda Fininsa Harjit Singh Lemma Dessalegne Anhild Andersson Roland Sigvald 《Euphytica》2010,172(1):77-91
The productivity and marketable quality of hot pepper (Capsicum annuum var. annuum L.) are low in tropical regions mainly due to virus infections and lack of effective virus management strategies. The absence
of effective virus management strategies could be attributed to lack of information on virus vectors and host resistance.
Parental (P1 and P2) and progeny (F1, B1, B2 and F2) generations of five hot pepper crosses were grown in Ethiopia at three sites (Bako, Hawasa and Melkasa) to monitor number
and species of potential aphid vectors, disease incidence levels with regards to natural infections by Potato virus Y (PVY) and Ethiopian pepper mottle virus (EPMV) complex, and to determine genetic tolerance of the crop to the viruses. Disease incidence was assessed before the
flowering stage of the crop plants using visible disease symptoms due to infections by PVY and EPMV. The serological tests
revealed presence of symptomless genotypes of the crop to the virus infections. Aphid species potentially transmitting the
viruses, such as Acyrthosiphon pisum (Harris), Aphis fabae (Scopoli), and Myzus persicae (Sulzer), were identified from specimens caught by yellow water traps. The highest number of aphids from yellow water traps
was recorded at a dense foliage growth stage of the crop at Melkasa. Highly significant variation was observed among generations
of the five crosses in response to infections by PVY and EPMV complex. The most susceptible parents had the levels of disease
incidences ranging from 80 to 90%, whereas their progenies had only below 30% incidence levels. The most tolerant parent remained
symptomless to the natural infections of PVY- and EPMV-complex. Incidence levels in progenies of a cross from the most susceptible
and tolerant parents remained below 20%. Based on serological test, the proportion of PVY-positive plants ranged from 0 to
75% and of EPMV-positive plants from 0 to 25%, with 0 to 17% co-infection by the two viruses. Availability of virus sources
in the vicinity, efficiency of aphids in vectoring, weather conditions during the growth period, genetic tolerance and the
growth stage of the crop affected natural infection by PVY- and EPMV-complex. Exploitation of the genetic potential of introduced
elite genotypes and their progenies along with breeding elite local cultivars for resistance and excluding aphid vectors at
young (seedling) stage of the crop plants could be helpful for minimizing losses in yield and quality of hot pepper due to
infections by PVY- and EPMV-complex. 相似文献
75.
76.
Stefanie Raabe Jörg Müller Michael Manthey Oliver Dürhammer Ulrich Teuber Axel Göttlein Bernhard Förster Roland Brandl Claus Bässler 《Forest Ecology and Management》2010
Understanding the major drivers of diversity in forests is crucial for ecologists, conservationists, and particularly forest managers. In most forested habitats, bryophytes are diverse and important primary producers. Here we report the first study of the relative importance of regional macroclimate as compared to local variables on abundance, species richness, and community composition of bryophytes growing in soil and in dead wood in a mountain temperate forest. Using PCA axes, we built predictor sets for macroclimate, microclimate, soil attributes, and dead wood availability. The explanatory power of each set was tested using variance partitioning. Abundance and species richness of soil bryophytes was best explained by microclimate, whereas the community composition did not distinctively differ between the environmental sets. In contrast, dead wood bryophyte abundance, species richness, and community composition was clearly driven by macroclimate. Among the single axes, the component represented best by soil moisture was the main driver for soil bryophyte abundance. In contrast, dead wood bryophyte abundance was mostly affected by components correlated with minimum global radiation and minimum temperatures as well as by the component represented by dead wood. The component represented by canopy openness was superior in explaining the community composition of both soil and dead wood bryophytes. We conclude that (1) dead wood amounts should be increased in closed stands to act as a buffer during climate changes, and (2) open canopy, which provides important habitats for soil-inhabiting bryophytes, should be provided by management with slow reforestation after natural or logging openings. 相似文献
77.
Roland W. S. Weber 《Erwerbs-Obstbau》2010,52(1):27-32
Isolates of Botrytis cinerea collected from Northern German strawberry and raspberry farms were grouped into three categories according to their pattern of resistance against the fungicide fenhexamid. Strains with baseline sensitivity showed EC50 values of 0.06–0.10 ppm (conidial germ-tube elongation) and 0.07–0.16 ppm (mycelial growth assay). For partially resistant isolates, the corresponding EC50 values were similar for germ-tube elongation but higher (> 0.39 ppm) for mycelial growth. Highly resistant isolates produced more than 50% growth in both assays even at 200 ppm fenhexamid, the highest concentration tested. These isolates matched the criteria of resistance group Hyd R3. By means of a simple test consisting of the harvesting of conidia from sporulating field samples and their direct assay by germ-tube elongation, Hyd R3 resistance was identified within 24 h of sampling. If this assay is performed on overwintered samples prior to blossom time, site-specific recommendations about the use of fenhexamid can be made to the farmer during the running vegetation period. 相似文献
78.
Dirk Jungmann Cornelia Bandow Thomas Gildemeister Roland Nagel Thomas G. Preuss Hans T. Ratte Cândida Shinn Lennart Weltje Hanna M. Maes 《Journal of Soils and Sediments》2009,9(2):94-102
Background, aim, and scope
Fenoxycarb is an insect growth regulator widely used to control a variety of pests. As a juvenile hormone analogue, it interacts with the natural hormones involved in insect development, inhibiting metamorphosis to the adult stage. Adverse effects of fenoxycarb on non-target organisms have been repeatedly observed and its rapid dissipation from water to the organic fraction of the sediment is known. The aim of this work was to investigate the impact of fenoxycarb on the development of sediment-dwelling larvae of the midge Chironomus riparius after exposure to spiked sediment. 相似文献79.
80.
In the summer of 2010 and during the following two seasons, a twig dieback of blueberries (Vaccinium corymbosum) was observed in southern Lower Saxony especially in younger plantations of the variety ‘Duke’. The sudden onset of a chlorosis and necrosis of individual twigs was associated with a destruction of the vascular cambium and with longitudinal streaks of brown discolourations in the xylem tissue deposited during the previous year. New shoots were often formed from the intact roots and from regions of older twigs located immediately above the soil surface. Potentially pathogenic fungi, including Godronia cassandrae, Phomopsis spp., Diplodia seriata, Pestalotiopsis sp., Paraconiothyrium sporulosum, Colletotrichum acutatum, Fusarium avenaceum and F. lateritium, were found sporadically on dead twigs, each fungus being present in 6 or fewer of the 12 plantations surveyed. Winter frost damage of xylem tissues was determined to be the main cause of the disease, facilitated by a delayed termination of vegetative growth which led to a lack of winter hardiness at the time-point of the first serious frost events. 相似文献