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排序方式: 共有196条查询结果,搜索用时 15 毫秒
191.
Schaefer O Bohlmann R Schleuning WD Schulze-Forster K Hümpel M 《Journal of agricultural and food chemistry》2005,53(8):2881-2889
Seven carboxylic acid haptens of 8-prenylnaringenin (8-PN) were synthesized, coupled to cationized bovine serum albumin, and employed to raise specific antisera in rabbits. Two linkers of different lengths (C3H6COOH and C6H12COOH) were coupled to the C7-OH group and separated into their respective enantiomers yielding the first four haptens. Racemic derivatives with C4'-OH coupled linkers C5H10COOH and C9H18COOH were synthesized carrying a methylated C7-OH. Another racemic C4'-OH hapten (CH2COOH) was prepared starting from naringenin. The haptens elicited variable antibody titers dependent on linker lengths, with short linkers giving the best results. Three antisera were characterized in detail: anti-C7-carboxy-propyloxy-2S-(-)-8-PN (anti-H-11), anti-C7-carboxy-propyloxy-2R-(+)-8-PN (anti-H-10), and anti-C4'-carboxy-methoxy-rac-8-PN (anti-H-25). anti-H-10 and anti-H-11 showed about 9% enantiomeric cross-reactivity, and anti-H-11 did not discriminate between isoxanthohumol (IX) and 8-PN (84% cross-reactivity). For anti-H-10, cross-reactivities in the range of 2-5% were found for xanthohumol, IX, and 6-prenylnaringenin. Respective numbers for anti-H-25 were 0.02, 0.1, and 0.2%. Tritiated 8-PN was synthesized yielding a 3H-tracer of high specific radioactivity (2.22 GBq/mg). A radioimmunoassay using anti-H-25 and 3H-8-PN was established and used for the quantitative determination of 8-PN in various beer brands and in the urine of six men after the consumption of three different brands of beer. Furthermore, the dose-dependent excretion of 8-PN was tested after the consumption of a higher volume of a single beer brand with and without spiking with 8-PN and a small oral dose of authentic 8-PN, respectively. Conflicting results led to a pilot test on the in vivo conversion (demethylation) of IX into 8-PN in two men. Conversion rates of 1.9 and 4.4% were estimated. Thus, the total 8-PN dose in beer brands spiced with natural hop or hop products seems to be the sum of the 8-PN amount in a consumed volume and the amount arising from the conversion of IX. 相似文献
192.
Jonathon D. Kotwa Manuela Schnyder Claire M. Jardine Peter Deplazes David L. Pearl Olaf Berke Nicola Mercer Andrew S. Peregrine 《Journal of veterinary diagnostic investigation》2021,33(4):664
In North America, the only endemic focus for Angiostrongylus vasorum (French heartworm) was historically thought to occur in the southeastern part of the island of Newfoundland. However, reports of A. vasorum infection in wild canids in West Virginia, USA, and Nova Scotia, Canada, suggest the introduction of the parasite to mainland North America. We screened for A. vasorum in coyotes from across southern Ontario. Additionally, we evaluated the performance of ELISAs for detection of circulating A. vasorum antigen (Ag-ELISA) and antibodies against A. vasorum (Ab-ELISA) designed for use in sera or blood of foxes for use with coyotes in this region. Autopsies were performed on 397 coyotes, and lung tissue extract prepared from each carcass was tested via both ELISAs. The sensitivity and specificity for both tests were estimated in the absence of a gold standard using a 2-test single population Bayesian model; sensitivity and specificity priors were based on the performance of the assays in foxes in Switzerland. Eight coyotes tested positive for A. vasorum antigen; no animal was antibody positive. The estimated sensitivity and specificity of the Ag-ELISA were 90.8% (95% credible interval [CrI]: 83.8–95.6%) and 95.5% (95% CrI: 93.4–97.2%), respectively. For the Ab-ELISA, the estimated sensitivity and specificity were 41.9% (95% CrI: 32.1–51.9%) and 98.0% (95% CrI: 96.3–99.0%), respectively. Based on these findings and negative postmortem data for the same animals, there is insufficient evidence to suggest the presence of A. vasorum in southern Ontario coyotes. 相似文献
193.
Olaf Schwab Thomas Maness Gary Bull Clive Welham Brad Seely Juan Blanco 《Forest Policy and Economics》2011,13(1):61-68
Assessing the impacts of cumulative, non-lethal damages to forests poses a particular challenge to forest management planning since cumulative merchantable volume losses are not known until the time of harvest. This paper introduces a model that scales stand-level processes to their large-scale implications by combining elements of growth and yield modeling, insect infestation modeling, and large-scale spatial harvest simulation. The model is described and tested using the proposed large-scale introduction of weevil-resistant spruce in British Columbia, Canada as a case study. While spruce weevil damages were found to be significant, only a relatively small percentage of losses can be avoided by planting resistant stock. The model introduced in this paper can serve as an important decision support tool for policy makers and researchers in assessing the large-scale effects of proposed policy and management interventions. 相似文献
194.
Deres K Schröder CH Paessens A Goldmann S Hacker HJ Weber O Krämer T Niewöhner U Pleiss U Stoltefuss J Graef E Koletzki D Masantschek RN Reimann A Jaeger R Gross R Beckermann B Schlemmer KH Haebich D Rübsamen-Waigmann H 《Science (New York, N.Y.)》2003,299(5608):893-896
Chronic hepatitis B virus (HBV) infection is a major cause of liver disease. Only interferon-alpha and the nucleosidic inhibitors of the viral polymerase, 3TC and adefovir, are approved for therapy. However, these therapies are limited by the side effects of interferon and the substantial resistance of the virus to nucleosidic inhibitors. Potent new antiviral compounds suitable for monotherapy or combination therapy are highly desired. We describe non-nucleosidic inhibitors of HBV nucleocapsid maturation that possess in vitro and in vivo antiviral activity. These inhibitors have potential for future therapeutic regimens to combat chronic HBV infection. 相似文献
195.
A PINOID-dependent binary switch in apical-basal PIN polar targeting directs auxin efflux 总被引:1,自引:0,他引:1
Friml J Yang X Michniewicz M Weijers D Quint A Tietz O Benjamins R Ouwerkerk PB Ljung K Sandberg G Hooykaas PJ Palme K Offringa R 《Science (New York, N.Y.)》2004,306(5697):862-865
Polar transport-dependent local accumulation of auxin provides positional cues for multiple plant patterning processes. This directional auxin flow depends on the polar subcellular localization of the PIN auxin efflux regulators. Overexpression of the PINOID protein kinase induces a basal-to-apical shift in PIN localization, resulting in the loss of auxin gradients and strong defects in embryo and seedling roots. Conversely, pid loss of function induces an apical-to-basal shift in PIN1 polar targeting at the inflorescence apex, accompanied by defective organogenesis. Our results show that a PINOID-dependent binary switch controls PIN polarity and mediates changes in auxin flow to create local gradients for patterning processes. 相似文献
196.
To date, the most widely adopted resource conserving technology in the Indo-Gangetic Plains (IGP) of South Asia has been zero-tillage (ZT) wheat after rice, particularly in India. The paper reviews and synthesizes the experience with ZT in the Indian IGP. ZT wheat is particularly appropriate for rice–wheat systems in the IGP by alleviating system constraints by allowing earlier wheat planting, helping control the weed Phalaris minor, reducing production costs and saving water. ZT wheat after rice generates substantial benefits at the farm level (US$97 ha−1) through the combination of a ‘yield effect’ (a 5–7% yield increase, particularly due to more timely planting of wheat) and a ‘cost savings effect’ (US$52 ha−1, particularly tillage savings). These benefits explain the widespread interest of farmers and the rapidity of the diffusion across the Indian IGP, further aided by the wide applicability of this mechanical innovation. 相似文献