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51.
Europe’s woodland and savanna rangelands, often part of silvopastoral systems known as wood-pastures, are deteriorating because of abandonment that leads to return to a forested state or lack of tree regeneration from overgrazing or tree and shrub removal. Despite numerous local studies, there has been no broader survey of the stand structure of European wood-pastures showing which systems are at risk of losing their semiopen character. This overview aims to 1) show some of the differences and similarities in wood-pastures from landscapes across Europe and 2) identify which of these wood-pastures are at risk of losing their semiopen character. We collated a dataset of 13 693 trees from 390 plots in wood-pastures from eight different European regions (western Estonia, eastern Greece, northern Germany, Hungary, northern Italy, southern Portugal, central Romania, and southern Sweden), including tree diameters at breast height, tree density, management type, and tree species composition. On the basis of their structural characteristics, we classified wood-pastures using principal component analysis (PCA) and cluster analysis. The PCA showed a gradient from dense wood-pastures with high levels of regeneration (e.g., in Estonia) to sparse wood-pastures with large trees but a lack of regeneration (e.g., in Romania). Along this gradient, we identified three main groups of wood-pastures: 1) sparse wood-pastures with mostly big trees; 2) dense wood-pastures composed of small trees, and 3) wood-pastures containing a wide range of tree ages. Our results show a large structural gradient in European wood-pastures, as well as regeneration problems varying in their severity, highlighting the importance of social-ecological context for wood-pasture conditions. To maintain the ecological and cultural integrity of European wood-pastures, we suggest 1) more comprehensively considering them in European policies such as the Common Agricultural Policy and EU Habitats Directive, while 2) taking into account their structural characteristics and social-ecological backgrounds.  相似文献   
52.
Five winter wheat cultivars--GK Othalom (HMW-GS composition 2*, 7+8, 5+10), Ukrainka (1, 7+8, 5+10), Palotás (2*, 7+9, 5+10), K?dm?n (2*, 7+8, 5+10), and Csongrád (2*, 7+9, 2+12)--grown in Hungary and harvested in the year 2005 were studied. The biosynthesis of gluten-forming polypeptides was followed starting at the 12th day after anthesis to the 53rd. Fresh kernel weight, moisture, and dry matter content of fresh kernels and gliadin and glutenin contents were determined. Gliadin components, total amounts of HMW and LMW polypeptides, and individual HMW polypeptides were determined using a RP-HPLC technique. Although considerable quantitative differences were observed concerning the content of total protein, gliadin, glutenin, and individual gluten-forming polypeptides, the character of accumulation of protein components--determined on the basis protein mass/kernel--was the same for the all of the cultivars studied and could be presented by a sigmoid curve. Small quantities of the gliadin and glutenin monomers may be detected in early stages of kernel development, but the bulk of these proteins is synthesized in later stages of development. It is generally suggested by specialists that the formation and accumulation of glutenin polymers starts later than the synthesis of monomers. Experimental data presented in this paper confirm this suggestion and show that in the first phase of protein synthesis the monomers are in "free" form; polymeric glutenin is detected only later. HMW glutenin subunits are synthesized synchronously, and quantitatively the polypeptides coded by chromosomes D and B dominate.  相似文献   
53.
 Fatty acid methyl ester (FAME) analysis is commonly used by soil scientists as a sole method for identifying soil bacteria. We observed discrepancies with this method for identifying certain species of bacteria. Therefore, we used carbon substrate oxidation patterns (BIOLOG) and some simple physical and chemical tests to determine the extent of these discrepancies. Identification with FAME profiles gave false positives for Arthrobacter globiformis, Micrococcus kristinae, and M. luteus, and identification with BIOLOG patterns gave a false positive identification for A. globiformis. A visual check and Gram stain are recommended when FAME analysis identifies soil isolates as M. kristinae or M. luteus, and an additional spore formation test is recommended when FAME and BIOLOG analyses identify isolates as A. globiformis. Received: 14 January 2000  相似文献   
54.
Yield and quality reductions caused by Fusarium head blight (FHB) have spurred spring wheat (Triticum aestivum L.) breeders to identify and develop new sources of host plant resistance. Four wheat synthetic hexaploids (×Aegilotriticum sp.) were developed, each having a quantitative trait locus (QTL), Qfhs.ndsu‐3AS, providing FHB resistance from Triticum turgidum L. var. dicoccoides chromosome 3A. Synthetics were produced by hybridizing a ‘Langdon’‐T. dicoccoides‐ recombinant chromosome 3A substitution line (2n = 4x = 28, AABB with two accessions of T. tauschii (2n= 2x = 14, DD). Synthetics were inoculated and evaluated for FHB resistance in two separate greenhouse seasons. One synthetic, 01NDSWG‐5, exhibited FHB severity ratings of 36% and 32% in the separate seasons, compared with ratings of 9% and 30% for ‘Alsen’, a FHB‐resistant spring cultivar, and ratings of 70% and 96% for ‘McNeal’, a susceptible spring cultivar, respectively. Synthetic × Alsen backcross‐derived lines were produced to initiate combining different sources of FHB resistance.  相似文献   
55.

Purpose

Ferromanganese nodules are common features in aquic soils of the temperate climate. Although they are intensively studied due to their pedogenic significance, there is a lack of knowledge on the relationship between their micro-fabric and distribution of their major chemical components. Our aim was to fill this gap and to relate these characteristics to the different stages of the nodule development in the soil.

Materials and methods

To fulfill our aims, ferromanganese nodules from a gleyic fluvisol profile was separated in which nodules with strongly varying appearance and fabric are present in a wide depth interval, so they are expected to represent the different stages of nodule formation. Micro-chemical analyses were carried out on the polished surface of 28 nodules. Micro-X-ray fluorescence spectrometry was used to produce Fe and Mn elemental maps of the whole nodules as well as line scan analyses along perpendicular cross sections. Additionally, the spatial distribution and major element associations of Fe and Mn within the individual nodules were studied by point analyses at 775 spots by electron micro-probe analysis.

Results and discussion

Typic and concentric nodules in the soil exhibited both similar (presence of outer coating band) and different (undifferentiated and banded interiors, respectively) characteristics in their micro-fabric. These were related to the rate of hydromorphism in the soil which was found to determinate the major processes (accretion vs. impregnation) forming the fabric of the nodules. The following stages of the nodule development were distinguished: (1) cementation, (2) formation of outer band, (3) re-arrangement and slow impregnation of nodules’ interior, and (4) fast impregnation of the interior and exfoliation of outer band. We found that separation of Fe and Mn is characteristic of each stage of nodule formation. However, as long as spatial segregation occurs in the first stages, displacement of Mn by Fe is rather typical later.

Conclusions

Fabric and appearance of nodules form by varying rate and dominance of accretion and impregnation relatively slowly. However, distribution pattern of Fe and Mn within the nodules may exhibit much faster changes simultaneously. Complex micro-chemical analyses support a powerful tool to follow such changes and to get a deeper insight into the genesis of ferromanganese nodules.
  相似文献   
56.
We evaluated ground beetle diversity in relation to forest edge between an oak-hornbeam forest and adjacent herbaceous grassland. To test our hypothesis that the diversity of ground beetles was higher in the forest edge than the interior, pitfall trap samples were taken along two forest-grassland transects in northern Hungary. The diversity of ground beetles was significantly higher at the forest edge and in the grassland than in the forest interior. Ground beetle assemblages in the forest interior, forest edge and grassland could be separated from each other by ordination. Indicator species analysis detected five groups of species: habitat generalists, grassland-associated species, forest generalists, forest specialists, and edge-associated species. Rank correlation indicated leaf litter, herb, canopy cover, and prey abundance as the most important factors influencing carabid diversity. The high diversity of the forest edge resulted from the presence of edge-associated species and of species characteristic of adjacent habitats. Forest edges seem to play an important role in maintaining diversity. Serving as source habitats, edges also contribute to the recolonisation by ground beetles after habitat destruction or other disturbance in the adjacent habitats.  相似文献   
57.
58.
Autologous vascular patch grafts developed from the internal rectus sheath were implanted onto the bilateral common iliac vein and jugular vein of 4 experimental beagle dogs. During the development and implanting of the grafts no technical difficulties or perioperative complications were encountered. The follow-up lasted 6 months and 3 months in the case of the common iliac vein grafts and the jugular grafts, respectively. In the postoperative period, the morphological and functional characteristics of the implanted venous sections were examined by Doppler ultrasonography and CT angiography. Normal patency was detected, and none of these check-ups showed obturation or stenosis. The histological survey showed no mesothelial cell layer, but the insides of the grafts showed total restructuring and were covered by a normal endothelial layer. No difference could be detected between samples harvested 3 and 6 months after implanting. The immunohistochemical examinations using anti-claudin-5 and anti-CD31 antibodies confirmed the preliminary results of the histological examinations that the luminal surfaces of the implanted grafts developed a differentiated monolayer endothelium which was free of degenerative and inflammatory signs. The control examinations show the suitability of the internal rectus sheath as a venous wall donor.  相似文献   
59.
In 2009, 26 clinical samples (organs and oral/cloacal swabs) from a total of 24 corn snakes (Pantherophis guttatus) from a single owner were sent to our laboratory to be tested for the presence of viruses. Paramyxoviruses (PMV), adenoviruses (AdV) and reoviruses were detected by RT-PCR, PCR and virus isolation methods. Three snakes were infected with all three viruses at the same time, while two other snakes had a double infection (PMV and reo, AdV and reo) and nine other snakes had a single infection with any of the three viruses. No viruses were detected in 10 animals. All isolated reoviruses were identical to one another and to the reptilian orthoreovirus isolate 55-02 in the partial RNA dependent RNA polymerase (RDRP) gene sequence. AdV partial polymerase sequences represented four different types, one of which was first described here: most similar to SnAdV-1, while the other three were identical to known types: SnAV-1, -2 and -3. However, the detected single PMV differed distinctly from described reptile PMV and was a new type. According to partial L gene, HN gene and U gene sequences it may be the first described representative of a third squamatid PMV cluster: "group C" within the proposed reptilian PMV genus "Ferlavirus". Nucleotide identity values for the L gene of the new PMV compared to group A viruses range between 76.5 and 80.3%, and between 80.5 and 81.2% compared to group B viruses. For the HN gene, these values were similar: 78.2-80% (A) and 79.9-80.5% (B) and somewhat lower for the U gene: 72.7-75.4% (A) and 69.7-70% (B). No reports on the prevalence of concurrent viral infection in captive snake populations have been published so far. The possibility of concurrent infection with several different viruses and subsequent consequences for animal health should be kept in mind when testing reptile samples for viruses.  相似文献   
60.
The effect of liming materials was investigated on the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) content of the soil in a pot experiment on an acidic soil using oat (Avena sativa L. ) as an indicator plant. Soil samples were taken three times during the growing season. The lime rates applied were 0, 1, 2, 3 g calcite/pot and 0.92, 1.84, 2.76 g dolomite/pot, respectively. Due to an increase in soil pH and microbial activity the DOC concentration significantly increased with increasing lime doses at all three samplings. An exponential relationship was found between soil pH and DOC concentration: y v = v 0.3733e 0.7893x , r v = v 0.903***. Lime had a significant effect on DON concentration at the first sampling, while for the remainder of the growing period no further significant increases were found. This could be explained by the fact that the biodegradability of DOC and DON differs under conditions of the experiment, resulting in a decrease in the N content of the dissolved organic matter, while the amount of DOM and DOC increased with increasing pH. Because of the above mentioned facts the DOC/DON ratio increased significantly with liming. There were no significant changes in the dissolved organic carbon content of the soil during the 15-week growing period, while DON concentration decreased significantly. It can be explained by the initial addition of N fertilizer, which increased the DON quantity at the first sampling in the soil.  相似文献   
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