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排序方式: 共有142条查询结果,搜索用时 15 毫秒
91.
Costa Lucas Archer Leigh Ampatzidis Yiannis Casteluci Larissa Caurin Glauco A. P. Albrecht Ute 《Precision Agriculture》2021,22(4):1107-1119
Precision Agriculture - Identifying and quantifying the number and size of stomata on leaf surfaces is useful for a wide range of plant ecophysiological studies, specifically those related to... 相似文献
92.
The Knersvlakte in the Succulent Karoo Biome (South Africa) is known for its high plant diversity and endemism. In the course of establishing a conservation area there, we assessed baseline data for future management. We investigated the effects of grazing on the vegetation in terms of species diversity and composition as well as reproduction of selected species. Data were sampled on four adjacent farms, which were ungrazed, moderately or intensively grazed by sheep and goats. The data were collected in 27 quartz and 24 non-quartz plots, representing two major habitat types of the region. Within each of the 1000-m2 plots, 100 subplots of 400 cm2 size were sampled. ANOVAs revealed that species richness and abundance of endemic species on quartz fields decreased with grazing. Abundance of annuals did not increase significantly due to grazing. Fidelity analyses indicated that species composition differed between grazing intensities and that the ungrazed and moderately grazed plots both contained unique locally endemic habitat specialists. Reproduction of two endemic dwarf shrubs Drosanthemumschoenlandianum and Argyrodermafissum (both Aizoaceae) increased under moderate grazing, which in the case of D.schoenlandianum was interpreted as an effect of grazing. We attribute the low number of seedlings and annuals on the moderately grazed farm to lower seasonal rainfall on these plots. From a conservation perspective, no or moderate grazing appear to be necessary to preserve plant diversity and vegetation patterns, and their underlying processes. 相似文献
93.
Choi M Scholl UI Yue P Björklund P Zhao B Nelson-Williams C Ji W Cho Y Patel A Men CJ Lolis E Wisgerhof MV Geller DS Mane S Hellman P Westin G Åkerström G Wang W Carling T Lifton RP 《Science (New York, N.Y.)》2011,331(6018):768-772
Endocrine tumors such as aldosterone-producing adrenal adenomas (APAs), a cause of severe hypertension, feature constitutive hormone production and unrestrained cell proliferation; the mechanisms linking these events are unknown. We identify two recurrent somatic mutations in and near the selectivity filter of the potassium (K(+)) channel KCNJ5 that are present in 8 of 22 human APAs studied. Both produce increased sodium (Na(+)) conductance and cell depolarization, which in adrenal glomerulosa cells produces calcium (Ca(2+)) entry, the signal for aldosterone production and cell proliferation. Similarly, we identify an inherited KCNJ5 mutation that produces increased Na(+) conductance in a Mendelian form of severe aldosteronism and massive bilateral adrenal hyperplasia. These findings explain pathogenesis in a subset of patients with severe hypertension and implicate loss of K(+) channel selectivity in constitutive cell proliferation and hormone production. 相似文献
94.
René Schreiber Anette Küster Ute Feiler Matthias Grote Rolf Altenburger 《Journal of Soils and Sediments》2011,11(8):1419-1431
Purpose
The objective of this study was to modify a sediment contact protocol to a multiwell plate exposure system which supplements measurement of the fresh weight change (FWC) using the non-invasive effective quantum yield of energy conversion at photosystem II (PS II) reaction centres (Y(II)) in parallel. Since Y(II) is a functional parameter and FWC represents a whole-plant structural response, the determination of a more pronounced response in one of these parameters may hint at the mode of action of contaminants. By the observation of Y(II) at different time points, extrapolation of effect development over time may be gained from modelling. 相似文献95.
96.
Joke Angenvoort Dominik Fischer Christine Fast Ute Ziegler Martin Eiden Jorge Garcia de la Fuente Michael Lierz Martin H Groschup 《Veterinary research》2014,45(1):41
West Nile virus (WNV) can lead to fatal diseases in raptor species. Unfortunately, there is no vaccine which has been designed specifically for use in breeding stocks of falcons. Therefore the immunogenicity and protective capacity of two commercially available WNV vaccines, both approved for use in horses, were evaluated in large falcons. One vaccine contained adjuvanted inactivated WNV lineage 1 immunogens, while the second represented a canarypox recombinant live virus vector vaccine. The efficacy of different vaccination regimes for these two vaccines was assessed serologically and by challenging the falcons with a WNV strain of homologous lineage 1. Our studies show that the recombinant vaccine conveys a slightly better protection than the inactivated vaccine, but moderate (recombinant vaccine) or weak (inactivated vaccine) side effects were observed at the injection sites. Using the recommended 2-dose regimen, both vaccines elicited only sub-optimal antibody responses and gave only partial protection following WNV challenge. Better results were obtained for both vaccines after a third dose, i.e. alleviation of clinical signs, absence of fatalities and reduction of virus shedding and viraemia. Therefore the consequences of WNV infections in falcons can be clearly alleviated by vaccination, especially if the amended triple administration scheme is used, although side effects at the vaccination site must be accepted. 相似文献
97.
Nitrogen oxides emission from soils bearing a potato crop as influenced by fertilization with treated pig slurries and composts 总被引:1,自引:0,他引:1
Antonio Vallejo Ute M. Skiba Augusto Arce Laura Sánchez-Martín 《Soil biology & biochemistry》2006,38(9):2782-2793
Nitrous oxide, nitric oxide and denitrification losses from an irrigated soil amended with organic fertilizers with different soluble organic carbon fractions and ammonium contents were studied in a field study covering the growing season of potato (Solanum tuberosum). Untreated pig slurry (IPS) with and without the nitrification inhibitor dicyandiamide (DCD), digested thin fraction of pig slurry (DTP), composted solid fraction of pig slurry (CP) and composted municipal solid waste (MSW) mixed with urea were applied at a rate of 175 kg available N ha−1, and emissions were compared with those from urea (U) and a control treatment without any added N fertilizer (Control). The cumulative denitrification losses correlated significantly with the soluble carbohydrates, dissolved N and total C added. Added dissolved organic C (DOC) and dissolved N affected the N2O/N2 ratio, and a lower ratio was observed for organic fertilizers than from urea or unfertilized controls. The proportion of N2O produced from nitrification was higher from urea than from organic fertilizers. Accumulated N2O losses during the crop season ranged from 3.69 to 7.31 kg N2O-N ha−1 for control and urea, respectively, whereas NO losses ranged from 0.005 to 0.24 kg NO-N ha−1, respectively. Digested thin fraction of pig slurry compared to IPS mitigated the total N2O emission by 48% and the denitrification rate by 33%, but did not influence NO emissions. Composted pig slurry compared to untreated pig slurry increased the N2O emission by 40% and NO emission by 55%, but reduced the denitrification losses (34%). DCD partially inhibited nitrification rates and reduced N2O and NO emissions from pig slurry by at least 83% and 77%, respectively. MSW+U, with a C:N ratio higher than that of the composted pig slurry, produced the largest denitrification losses (33.3 kg N ha−1), although N2O and NO emissions were lower than for the U and CP treatments.This work has shown that for an irrigated clay loam soil additions of treated organic fertilizers can mitigate the emissions of the atmospheric pollutants NO and N2O in comparison with urea. 相似文献
98.
99.
Usama Ramadan Abdelmohsen Chen Yang Hannes Horn Dina Hajjar Timothy Ravasi Ute Hentschel 《Marine drugs》2014,12(5):2771-2789
The diversity of actinomycetes associated with marine sponges collected off Fsar Reef (Saudi Arabia) was investigated in the present study. Forty-seven actinomycetes were cultivated and phylogenetically identified based on 16S rRNA gene sequencing and were assigned to 10 different actinomycete genera. Eight putatively novel species belonging to genera Kocuria, Mycobacterium, Nocardia, and Rhodococcus were identified based on sequence similarity values below 98.2% to other 16S rRNA gene sequences available in the NCBI database. PCR-based screening for biosynthetic genes including type I and type II polyketide synthases (PKS-I, PKS-II) as well as nonribosomal peptide synthetases (NRPS) showed that 20 actinomycete isolates encoded each at least one type of biosynthetic gene. The organic extracts of nine isolates displayed bioactivity against at least one of the test pathogens, which were Gram-positive and Gram-negative bacteria, fungi, human parasites, as well as in a West Nile Virus protease enzymatic assay. These results emphasize that marine sponges are a prolific resource for novel bioactive actinomycetes with potential for drug discovery. 相似文献
100.