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71.
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The mountainous environment of the Ethiopian highlands has a great variety of ecotopes and thus demands great flexibility in land management. Different climatic conditions and landscape positions induce different soil forming processes, leading to various soil types with specific risks and potentials. The present study portrays a soil sequence of the central section of the Main Ethiopian Rift Valley, from the footslopes of the eastern escarpment to the marginal volcano structures. Six profiles under natural vegetation are described for classification according to the USDA Soil Taxonomy and World Reference Base for Soil Resources classification systems, and special site characteristics are discussed. The Acacia savannah of the footslopes (1900 m a. s. l.) is characterized by Vertisols (Mazic Vertisols/Aridic Haplusterts), with often pronounced effects of seasonal waterlogging. All other soils are well-drained and reflect the general increase in rainfall with elevation and slope, causing a decline in topsoil pH and a change from cation-rich clay soils of the Podocarpus-dominated forest at 2300 m a. s. l. (Mollic Nitisols/Typic Palehumults) to strongly-leached Humic Umbrisols/Humic Dystrudepts of the Hagenia-dominated forest around 2600 m a. s. l. The highland savannah plain (2700 m a. s. l.) with a drier and cooler environment has typically Mollic Cambisols/Dystric Haplustepts, which are less leached and have a rather brownish colour. At 2900 m a. s. l., Niti-umbric Alisols/Andic Hapludalfs are found in the Hypericum forest at the midslopes of the marginal volcanoes receiving high rainfall, whereas soil development is at a more initial state in the Erica-dominated forest at 3200 m a. s. l. (Umbric Andosols/Alic Hapludands). Clay mineral composition is kaolinite-dominated for the upper five profiles, with a high proportion of poorly crystalline components in the upper savannah and the volcano upslopes. The lowermost profile probably has a polygenetic origin indicated by an abrupt change from a smectitic to a kaolinitic composition in the subsoil. Soil development on quite homogeneous bedrock appears essentially controlled by relief and climate, underlining the suitability of the region as a model area for in-depth gradient studies on ecosystem processes and land use. 相似文献
74.
The betalain pattern of differently colored Swiss chard (Beta vulgaris L. ssp. cicla [L.] Alef. cv. Bright Lights) was investigated for the first time. Nineteen betaxanthins and nine betacyanins were identified by RP-HPLC and positive ion electrospray mass spectrometry, co-injection experiments with semisynthetic reference compounds, and standards derived from authentic plant material, respectively. Histamine-betaxanthin and alanine-betaxanthin were found to be novel betaxanthins, which to the best of our knowledge have not been reported as natural compounds until now. Furthermore, tyramine-betaxanthin (miraxanthin III) and 3-methoxytyramine-betaxanthin, which to date were known only from families other than the Chenopodiaceae, were detected for the first time in colored Swiss chard. The betacyanin pattern of purple petioles was composed of betanin, isobetanin, betanidin, and isobetanidin. Although phyllocactin was present in only trace amounts, further acylated structures such as betanidin-monoferuloyl-5-O-beta-diglucoside and lampranthin II, accompanied by their corresponding C(15)-epimers, were identified. In addition, quantification of betalains and CIE LCh degrees measurements were performed with the colored extracts to correlate the visual appearance with the respective pigment patterns. Besides the novel phytochemical findings, the present study is useful for the evaluation of betalainic Swiss chard as a potential coloring foodstuff. 相似文献
75.
Summary The past 25 years, 1686 potato accessions, representing 100 species in the genus Solanum L., subgenus Potatoe, section Petota, were evaluated for field resistance to one or more of the following insect pests: green peach aphid, Myzus persicae (Sulzer); potato aphid, Macrosiphum euphorbiae (Thomas); Colorado potato beetle, Leptinotarsa decemlineata (Say); potato flea beetle, Epitrix cucumeris (Harris); and potato leafhopper, Empoasca fabae (Harris). Accessions highly resistant to green peach aphid were identified within 36 species, to potato aphid within 24 species, to Colorado potato beetle within 10 species, to potato flea beetle within 25 species, and to potato leafhopper within 39 species. Resistance levels were characteristic within Solanum species. Insect resistance appears to be a primitive trait in wild potatoes. Susceptibility was most common in the primitive and cultivated Tuberosa. Insect resistance was also characteristic of the most advanced species. The glycoalkaloid tomatine was associated with field resistance to Colorado potato beetle and potato leafhopper. Other glycoalkaloids were not associated with field resistance at the species level. Dense hairs were associated with resistance to green peach aphid, potato flea beetle, and potato leafhopper. Glandular trichomes were associated with field resistance to Colorado potato beetle, potato flea beetle, and potato leafhopper. Significant correlations between insect score and altitude of original collection were observed in six of thirteen species. Species from hot and arid areas were associated with resistance to Colorado potato beetle, potato flea beetle, and potato leafhopper. Species from cool or moist areas tended to be resistant to potato aphid.Abbreviations EBN
Endosperm Balance Number 相似文献
76.
77.
Mayr B Korb H Oppeneiger T Demetz F Egger J 《Veterinary journal (London, England : 1997)》2007,174(3):677-680
A combined primed in situ labelling (PRINS)/4',6-diamino-2-phenylindole (DAPI)/propidium iodide (PI)-fluorescence-banding method was used to characterise telomeres, identify their specific chromosomes and visualise neighbouring heterochromatin in 25 artificial insemination (AI) bulls. A highly heterogeneous telomere length pattern was found in cattle. Each bull possessed his own characteristic, specific telomere length pattern. 相似文献
78.
Gekeler F Gmeiner H Völker M Sachs H Messias A Eule C Bartz-Schmidt KU Zrenner E Shinoda K 《Veterinary ophthalmology》2007,10(3):173-178
OBJECTIVES: To assess the feasibility of optical coherence tomography (OCT) for examining the cat ocular fundus, to provide normative data on retinal thickness in different fundus regions, and to demonstrate selected surgically induced vitreoretinal pathologies in the cat. ANIMAL STUDIED: Forty-five eyes of 28 healthy domestic cats and two eyes of domestic cats that had undergone subretinal implantation surgery for a visual prosthesis were examined. PROCEDURES: An optical coherence tomograph (Zeiss-Humphrey) was used to examine the anesthetized animals. At least five vertical and five horizontal scans in regular distribution were recorded for each cat including (1) the peripapillary region, (2) the area centralis, and (3) the peripheral retina. Thickness was measured manually at five locations in each scan. Retinal thickness was compared in the three above-mentioned fundus regions, between eyes and between vertical and horizontal scans. OCT was additionally performed in animals with retinal detachment and a subretinal visual prosthesis. RESULTS: OCT measurements required only minimal adjustments of human settings and yielded high quality images. In comparison to humans intraretinal layers were more difficult to differentiate. Retinal thickness was highest in the peripapillary region (245 +/- 21 microm), followed by the peripheral retina (204 +/- 11 microm) and the area centralis (182 +/- 11 microm; all P < 0.0001). There was no statistically significant difference between right and left eye or between vertical and horizontal scans. OCT demonstrated retinal detachment, an iatrogenic break and a subretinal prosthetic device in high detail. CONCLUSIONS: Retinal thickness was measurable with high precision; values compare well to older histologic studies. OCT bears significant advantages over histology in enabling one to repeat measurements in living animals and thus allowing longitudinal studies. Various vitreoretinal pathologies common in feline eyes are detectable and quantifiable by OCT. 相似文献
79.
Background
Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as 'connectance' or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size. 相似文献80.