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41.
When vanillic acid was incubated with an extracellular laccase from the fungus Rhizoctonia praticola, the formation of various oligomeric products was observed ranging from dimers to pentamers. The three dimers isolated by thin-layer chromatography had molecular ions of 304, 304 and 334, respectively, which corresponded to two dimers (methoxy-p-benzoquinone-vanillic acid) with C-O (2-methoxy-6-(2'-methoxy-4'-carboxyphenoxy)-1,4-benzoquinone) and C-C (2-methoxy-6-(2'-hydroxy-3'-methoxy-5'-carboxyphenyl)-1,4-benzoquinone) coupling, and dehydrodivanillic acid (m/z 334) (2,2'-dihydroxy-3, 3'-dimethoxy-5,5'-dicarboxybiphenyl). The identity of these compounds and their methylated derivatives was confirmed by mass and NMR spectrometric analysis. The oxidative coupling of vanillic acid is also catalyzed by peroxidase but not by tyrosinase. 相似文献
42.
Gancel AL Ollitrault P Froelicher Y Tomi F Jacquemond C Luro F Brillouet JM 《Journal of agricultural and food chemistry》2005,53(6):2224-2230
Volatile compounds were extracted by a pentane/ether (1:1) mixture from the leaves of six citrus somatic allotetraploid hybrids resulting from various combinations of lime, lemon, citron, sweet orange, and grapefruit. Extracts were examined by gas chromatography-mass spectrometry (GC-MS) and compared with those of their respective parents. All hybrids having an acid citrus parent exhibit the same relative contents in hydrocarbons and oxygenated compounds as the acid citrus, while the (grapefruit + orange) hybrid behaves similarly to its two parents. When volatile compound contents (microg g(-1)) are examined in detail, several behaviors are encountered in hybrids and seem to depend on the presence/absence of the considered parental compound and on the corresponding hybrid combination. Meanwhile, the sesquiterpene hydrocarbons are present in all hybrids at concentrations systematically lower than those of the highest parental producers. Statistical analyses show that hybrids exhibit hardly discriminable aromatic profiles, meaning that no strong dominance of one or the other parent was observed in hybrids with regards to the leaf volatile compound production. 相似文献
43.
Brat P Rega B Alter P Reynes M Brillouet JM 《Journal of agricultural and food chemistry》2003,51(11):3442-3447
The quantitative distribution of volatile compounds in the pulp, cloud, and serum of a freshly squeezed orange juice (cv. Naveline) was measured. Juice monoterpene and sesquiterpene hydrocarbons were primarily recovered from the pulp (74.0 and 87.2%, respectively) and cloud (7.3 and 14.9%, respectively). Esters and monoterpene alcohols were mainly found in the serum (90.4 and 84.1%, respectively). Long chain aliphatic aldehydes tend to concentrate in the pulp. The relative proportions of individual volatile compounds were similar in the pulp and cloud. Pulp and cloud alcohol insoluble residues exhibited similar compositions; half of them are made of nonwall proteins, and the rest are made of cell wall materials. Pulp and cloud total and neutral lipids had similar fatty acids distributions, although the cloud was much richer in total lipids than the pulp. No relationship was found between the retention of aroma compounds in the pulp or cloud and their AIR and lipid content or composition. 相似文献
44.
45.
• Introduction
Size-density relationships define the maximum number of stems that even-aged stands of a given species can hold in relation to the mean size of trees. They are used to derive stand density measures and are useful tools used to control tree mortality. 相似文献46.
Nicolas Morellet Bram Van Moorter Bruno Cargnelutti Jean-Marc Angibault Bruno Lourtet Joël Merlet Sylvie Ladet A. J. Mark Hewison 《Landscape Ecology》2011,26(7):999-1010
Understanding how patterns of habitat selection vary in relation to landscape structure is essential to predict ecological
responses of species to global change and inform management. We investigated behavioural plasticity in habitat selection of
roe deer (Capreolus capreolus) in relation to variable habitat availability across a heterogeneous agricultural landscape at the home range and landscape
scales. As expected, woodland was heavily selected, but we found no functional response for this habitat, i.e. no shift in
habitat selection with changing habitat availability, possibly due to the presence of hedgerows which were increasingly selected
as woodlands were less abundant. Hedgerows may thus function as a substitutable habitat for woodlands by providing roe deer
with similar resources. We observed a functional response in the use of hedgerows, implying some degree of landscape complementation
between hedgerows and open habitats, which may in part compensate for lower woodland availability. We also expected selection
for woodland to be highest at the wider spatial scale, especially when this habitat was limiting. However, our results did
not support this hypothesis, but rather indicated a marked influence of habitat composition, as both the availability and
distribution of resources conditioned habitat selection. There was no marked between-sex difference in the pattern of habitat
selection at either scale or between seasons at the landscape scale, however, within the home range, selection did differ
between seasons. We conclude that landscape structure has a marked impact on roe deer habitat selection in agricultural landscapes
through processes such as landscape complementation and supplementation. 相似文献
47.
Vanilla bean beta-D-glucosidase was purified to apparent homogeneity by successive anion exchange, hydrophobic interaction, and size-exclusion chromatography. The enzyme is a tetramer (201 kDa) made up of four identical subunits (50 kDa). The optimum pH was 6.5, and the optimum temperature was 40 degrees C at pH 7.0. K(m) values for p-nitrophenyl-beta-D-glucopyranoside and glucovanillin were 1.1 and 20.0 mM, respectively; V(max) values were 4.5 and 5.0 microkat.mg(-1). The beta-D-glucosidase was competitively inhibited by glucono-delta-lactone and 1-deoxynojirimycin, with respective K(i) values of 670 and 152 microM, and not inhibited by 2 M glucose. The beta-D-glucosidase was not inhibited by N-ethylmaleimide and DTNB and fully inhibited by 1.5-2 M 2-mercaptoethanol and 1,4-dithiothreitol. The enzyme showed decreasing activity on p-nitrophenyl-beta-D-fucopyranoside, p-nitrophenyl-beta-D-glucopyranoside, p-nitrophenyl-beta-D-galactopyranoside, and p-nitrophenyl-beta-D-xylopyranoside. The enzyme was also active on prunasin, esculin, and salicin and inactive on cellobiose, gentiobiose, amygdalin, phloridzin, indoxyl-beta-D-glucopyranoside, and quercetin-3-beta-D-glucopyranoside. 相似文献
48.
François Allal Georges Piombo Bokary A. Kelly John B. L. Okullo Massamba Thiam Ousmane B. Diallo George Nyarko Fabrice Davrieux Peter N. Lovett Jean-Marc Bouvet 《Agroforestry Systems》2013,87(5):1065-1082
The shea tree, Vitellaria paradoxa, is one of the most economically and culturally important indigenous tree species in the Sudano-Sahelian region. Its seeds contain a vegetable fat, internationally known as shea butter, which is widely used in edible, cosmetic and pharmaceutical sectors. Based on samples from 456 trees distributed in 17 locations across the species natural range from Senegal to Uganda, the fatty acid and tocopherol variation, and its relationship with geographic and climatic variables, was assessed in order to address the pattern and the origin of this variation across the natural range. Significant differences between Western and Eastern regions for oleic, stearic acid, saturated–unsaturated acid ratio and γ-tocopherol were identified that it is postulated maybe a result of genetic drift due to the evolutionary history of shea tree populations. Within regions the difference among stands was significant for most constituents; however the major part of the variation was observed among trees within stand (53–90 %). Relationships with climatic variables were not verified, weakening evidence for clinal variation hypotheses suggested by previous studies. 相似文献
49.
Mélanie Villeret Sabrina Jolly Laure Wiest Emmanuelle Vulliet Anne Bado-Nilles Jean-Marc Porcher Stéphane Betoulle Christophe Minier Wilfried Sanchez 《Fish physiology and biochemistry》2013,39(3):573-580
The aim of this study was to identify a signal that could be used as an androgen exposure indicator in the European bullhead (Cottus sp.). For this purpose, the ultra-structure of the kidney was characterized to identify normal structure of this organ, and histological changes previously described in the kidney of breeding male bullheads were quantified using the kidney epithelium height (KEH) assay previously developed and validated for the stickleback. In the next step, the effect of trenbolone acetate (TbA), a model androgen, was assessed to identify potential androgenic regulation of bullhead kidney hypertrophy. Measurement of KEH performed on adult non-breeding male and female bullheads exposed for 14 and 21 days to 0, 1.26 and 6.50 μg/L showed that kidney hypertrophy is induced in a dose-dependent manner, confirming the hypothesis that the European bullhead possesses a potential biomarker of androgen exposure. Combined with the wide distribution of the European bullhead in European countries and the potential of this fish species for environmental toxicology studies in field and laboratory conditions, the hypothesis of a potential biomarker of androgen exposure offers interesting perspectives for the use of the bullhead as a relevant sentinel fish species in monitoring studies. Inducibility was observed with high exposure concentrations of TbA. Further studies are needed to identify molecular signals that could be more sensitive than KEH. 相似文献
50.
Pierrette Fleurat-Lessard Estelle Luini Jean-Marc Berjeaud Gabriel Roblin 《European journal of plant pathology / European Foundation for Plant Pathology》2014,139(1):137-150
Phaeoacremonium aleophilum is a fungal pathogen implicated in esca, a devastating disease affecting grapevines around the world. We have previously reported that the fungus secreted in its culture medium a variety of polypeptides, which allowed us to develop a serological method of detection. In this method, rabbit antibodies raised against the polypeptide fraction recognized secreted fungal proteins with high sensitivity (commonly 1 ng). These antibodies were specific since they cross-reacted with polypeptides secreted by various strains of Pm. aleophilum, but not with the proteins secreted by many other fungal pathogens implicated in other grapevine infections. Importantly, as shown by ELISA tests and immunolocalization, they did not cross-react with the secreted polypeptides of Eutypa lata (agent of Eutypa dieback), Neofusicoccum parvum (found in Black Dead Arm), and Phaeomoniella chlamydospora (also found in the fungal complex inducing esca). This serological approach permitted the development of a reliable dot-blot method to detect the presence in woody members of Pm. aleophilum in selectively infected trunk and canes. This method of diagnosis is rapid, easy to perform and non destructive for grapevines. Advantages and drawbacks of the method are discussed. 相似文献