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51.
Rajendran L Schneider A Schlechtingen G Weidlich S Ries J Braxmeier T Schwille P Schulz JB Schroeder C Simons M Jennings G Knölker HJ Simons K 《Science (New York, N.Y.)》2008,320(5875):520-523
beta-Secretase plays a critical role in beta-amyloid formation and thus provides a therapeutic target for Alzheimer's disease. Inhibitor design has usually focused on active-site binding, neglecting the subcellular localization of active enzyme. We have addressed this issue by synthesizing a membrane-anchored version of a beta-secretase transition-state inhibitor by linking it to a sterol moiety. Thus, we targeted the inhibitor to active beta-secretase found in endosomes and also reduced the dimensionality of the inhibitor, increasing its local membrane concentration. This inhibitor reduced enzyme activity much more efficiently than did the free inhibitor in cultured cells and in vivo. In addition to effectively targeting beta-secretase, this strategy could also be used in designing potent drugs against other membrane protein targets. 相似文献
52.
Angelika Kölbl Margit von Lützow Cornelia Rumpel Jean Charles Munch Ingrid Kögel‐Knabner 《植物养料与土壤学杂志》2007,170(1):123-133
The application of 13C‐labeled litter enables to study decomposition processes as well as the allocation of litter‐derived carbon to different soil C pools. 13Carbon‐labeled mustard litter was used in order to compare decomposition processes in an agricultural cropland with high‐yield (HY) and low‐yield (LY) areas, the latter being characterized by a finer texture and a lower organic‐C (OC) content. After tracer application, 13C concentrations were monitored in topsoil samples in particulate organic matter (POM) and in fine mineral fractions (silt‐ and clay‐sized fractions). After 568 d, approximately 5% and 10% of the initial 13C amount were found in POM fractions of LY and HY areas, respectively. Higher amounts were found in POM occluded in aggregates than in free POM. Medium‐term (0.5–2 y) storage of the initial 13C in fine silt‐ and clay‐sized fractions amounts to 10% in HY and LY soils, with faster enrichment but also faster disappearance of the 13C signal from LY soils. Amounts of 80%–90% of the added 13C were mineralized or leached in the observed period. Decomposition of free POM was faster in HY than in LY areas during the first year, but the remaining 13C amounts in occluded‐POM fractions were higher in HY soils after 568 d. High‐yield and low‐yield areas showed different 13C dynamics in fine mineral fractions. In LY soils, 13C amounts and concentrations in mineral‐associated fractions increased within 160 d after application and decreased in the following time period. In HY areas, a significant increase in 13C amounts did not occur until after 568 d. The results indicate initially faster decomposition processes in HY than in LY areas due to different soil conditions, such as soil texture and water regime. The higher silt and clay contents of LY areas seem to promote a faster aggregate formation and turnover, leading to a closer contact between POM and mineral surfaces in this area. This favors the OC storage in fine mineral fractions in the medium term. Lower aggregate formation and turnover in the coarser textured HY soil leads to a delayed C stabilization in silt‐ and clay‐sized fractions. 相似文献
53.
In the Lusatian mining district, rehabilitated mine soils contain substantial amounts of lignite in addition to recent carbon derived from plant litter. The aim of this study was to examine the importance of the two organic matter types as substrates for soil microbial biomass in mine soils containing organic matter with a contrasting degree of humification. Samples were taken from the lignite-containing overburden material, from a mine soil under 14-year-old black pine (Pinus nigra) and from a mine soil under 37-year-old red oak (Quercus rubra). Overburden material was ameliorated with alkaline ash and incubated in an identical manner as the 14-year-old and 37-year-old mine soils for 16 months. Carbon mineralisation was monitored throughout. After 0, 3, 6, 12 and 16 months, samples were removed and analysed for chemical parameters and for microbial biomass. In addition, 14C activity measurements in bulk soil and microbial biomass were used to estimate their lignite content.Despite the high content of organic carbon in lignite-rich overburden material, low contents of microbial biomass were recorded. Ash-amelioration led to high pH values in the overburden material, resulting in high concentrations of dissolved organic carbon most likely derived from lignite. Development of the microbial community was subsequently stimulated by presence of an easily available carbon source. In older mine soils, larger amounts of microbial biomass are most likely related to the presence of recent organic matter. Radiocarbon analysis of the microbial biomass extracted from the 14-year-old mine soil indicated higher lignite carbon contribution than recorded for microbial biomass of the 37-year-old mine soil. The highest concentration of lignite C present in microbial biomass as indicated by the Cmic/Corg ratio was, however, observed in the ameliorated overburden material. Therefore, we conclude that the importance of lignite as a carbon source for micro-organisms decreases when recent organic matter is present in the older stages of mine soil development. 相似文献
54.
Cornelia Lehmann Christoph Biela Stefan Töpfl Gisela Jansen Rudolf Vögel 《Euphytica》2007,158(1-2):189-199
The objective of this study was to examine the potential of Solanum scabrum to provide a colorant for food. We conducted a field trial with eight accessions from four different sources and recorded
both morphological variability and fruit yield differences between accessions. Further, anthocyanin and glucoalkaloid concentrations
were determined. The accessions could be assigned to two distinct groups: a leafy vegetable type with toxic fruits used in
Africa and a berry type with edible fruits known as Garden Huckleberry in North America, but both types had edible leaves
with low glucoalkaloid concentrations. The leafy vegetable type set not much fruit. In contrast, the berry type yielded on
average 800–900 g berries per plant with remarkable high anthocyanin concentrations of 8.1–13.9 g kg−1 fresh weight, calculated as petunidin 3-p-(coumaryl-runtinoside)-5-glucoside. Thus, S. scabrum can serve as a source for natural anthocyanin pigments. In particular, two accessions with a high fruit yield were promising
candidates as a berry crop. One had the best anthocyanin concentration of the examined material and the other one had a low
percentage of unripe berries as a further advantage. 相似文献
55.
• Introduction
Commercial thinning (CT) could contribute to increase short-term tree growth and be beneficial in a cold climate, as in boreal regions. Thus, growth rate, ring density and flexural modulus of elasticity (MOE) of trees may change after CT. Moreover, mechanical wood properties vary with position in the tree, and there is a need to develop optimal log allocation strategies in order to allocate logs to their best use. 相似文献56.
57.
Strålsjö LM Witthöft CM Sjöholm IM Jägerstad MI 《Journal of agricultural and food chemistry》2003,51(1):128-133
Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH(3)-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 microg/100 g of dry matter (DM) for cv. Senga Sengana to 644 microg/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degrees C (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries ( approximately 125 microg of folate) supplies approximately 50% of the recommended daily folate intake in various European countries (200-300 microg/day) or 30% of the U.S. recommendation (400 microg/day). 相似文献
58.
59.
Gilroy C Forzán M Drew A Vernau W 《The Canadian veterinary journal. La revue veterinaire canadienne》2011,52(9):1004-1008
A 4-year-old castrated male domestic shorthaired cat with a history of vomiting and anorexia was diagnosed with leukemia with marked hepatic and splenic infiltration and concurrent eosinophilia with marked tissue infiltration. Despite thorough immunocytochemical and immunohistochemical immunophenotyping, the cell lineage of the leukemia was not identified. 相似文献
60.
Barbara Esteve-Ratsch DMV Sibylle Kneissl DMV Cornelia Gabler DMV 《Veterinary radiology & ultrasound》2001,42(5):410-413
MR images provide for the exact assessment of the brain, including ventricular size. Still inter- and intrabreed comparison of ventricle size is difficult due to the varying anatomies in dogs. To compare the ventricle area of different sized breeds, 25 dogs (13 Yorkshire Terriers and 12 German Shepard dogs) were reviewed, retrospectively. Hemisphere and ventricle of each side were outlined manually three times. All measurements were averaged and their percentage (ventricle area by hemisphere area) was defined as the relative ventricle area. This value in Yorkshire Terriers (5.3) was significantly higher compared to German Shepard dogs (1.7). However, on the basis of the neurologically symptomatic sample (7 Yorkshire Terriers) in this study, threshold values of normal and abnormal relative ventricle areas could not be detected. 相似文献