全文获取类型
收费全文 | 248篇 |
免费 | 11篇 |
专业分类
林业 | 19篇 |
农学 | 1篇 |
基础科学 | 2篇 |
46篇 | |
综合类 | 25篇 |
农作物 | 17篇 |
水产渔业 | 8篇 |
畜牧兽医 | 124篇 |
园艺 | 3篇 |
植物保护 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 5篇 |
2017年 | 10篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 26篇 |
2010年 | 16篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 5篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有259条查询结果,搜索用时 15 毫秒
41.
Vergara C von Baer D Mardones C Wilkens A Wernekinck K Damm A Macke S Gorena T Winterhalter P 《Journal of agricultural and food chemistry》2012,60(4):929-933
Health benefits of trans-resveratrol and other stilbenes in grapes, must, and wine have been pointed out by numerous authors. Less attention has been paid to the presence of stilbene derivatives in viticultural residues, such as grape canes. The present work reports the first results of a systematic study of stilbene levels in different grape varieties and cultivation areas in Chile, to evaluate their potential as an alternative source of bioactive stilbenes. In all cane samples, the predominant stilbene is trans-resveratrol, followed by ε-viniferin and piceatannol. In canes of Pinot noir up to 5590 ± 172 mg kg(-1) of trans-resveratrol and up to 6915 ± 175 mg kg(-1) of total stilbenes were detected. The observed concentrations of stilbenes in canes of Pinot noir from southern Chile until now are higher than those reported previously for this red variety. However, the highest concentration of total stilbenes observed in the analyzed samples was in the canes of white variety Gewürztraminer with 7857 ± 498 mg kg(-1). Preliminary results indicate that these levels can evolve if canes are left for some months on the vineyard after pruning, observing an increase during the first 2 months and a decrease after this period. 相似文献
42.
Timothy J. Sullivan Bernard J. Cosby Todd C. McDonnell Ellen M. Porter Tamara Blett Richard Haeuber Cindy M. Huber Jason Lynch 《Water, air, and soil pollution》2012,223(9):5759-5771
The purpose of the research described here is to apply a new approach for generating aquatic critical load (CL) and exceedance calculations for an important acid-sensitive region of the eastern USA. A widespread problem in regional aquatic acidification CL modeling for US ecosystems has been the lack of site-specific weathering data needed to derive accurate model CL estimates. A modified version of the steady-state water chemistry CL model was applied here to estimate CL and exceedances for streams throughout acid-sensitive portions of Virginia and West Virginia. A novel approach for estimating weathering across the regional landscape was applied, based on weathering estimates extracted from a well-tested, process-based watershed model of drainage water acid?Cbase chemistry and features of the landscape that are available as regional spatial data coverages. This process allowed extrapolation of site-specific weathering data from 92 stream watersheds to the regional context in three ecoregions for supporting CL calculations. Calculated CL values were frequently low, especially in the Blue Ridge ecoregion where one-third of the stream length had CL?<?50?meq/m2/year to maintain stream ANC at 50???eq/L under steady-state conditions. About half or more of the stream length in the study region was in exceedance of the CL for long-term aquatic resource protection under assumed nitrogen saturation at steady state. Land managers and air quality policy makers will need this information to better understand responses to air pollution emissions reductions and to develop ecoregion-specific air pollution targets. 相似文献
43.
44.
45.
Hilma Peusha Tamara Enno Irena Jakobson Jelena Tsotildembalova Anne Ingver 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(4):289-296
Abstract A group of spring wheat cultivars originating from Sweden, Finland, Norway, Germany, and the Netherlands was analysed for powdery mildew resistance. Using functional molecular markers, two alleles of the major resistance gene Pm3 were detected among the cultivars under the study. One of the alleles, Pm3d, was detected in the resistant cultivars ‘Vinjett’, ‘SW Estrad’, and ‘Zebra’, and in ‘Tjalve’, a cultivar of earlier release susceptible to the local population of powdery mildew. The second allele of Pm3 detected in the analysed group of cultivars was the allele Pm3f, rarely used in Europe. It was identified in the resistant cultivars ‘Satu’, ‘Helle’, and in the moderatively resistant cultivar ‘Mahti’. Pm3f was found to be effective against the local population of powdery mildew in Estonia, while Pm3d provided no protective effect. Besides the Pm3d allele on chromosome 1A, monosomic analysis of the cultivar ‘Vinjett’,which is almost immune to powdery mildew, identified two additional loci on chromosomes 5D and 7D, respectively, presumably responsible for the high resistance in this cultivar. In contrast to the earlier cultivars, six recently released cultivars (‘Vinjett’, ‘SW Estrad’, ‘Zebra’, ‘Satu’, ‘Helle’, ‘Meri’) demonstrated a high resistance to the powdery mildew fungus Blumeria graminis DC. f. sp. tritici both in the field and seedling tests, showing that the genetic basis of powdery mildew resistance in Nordic spring wheat has been improved noticeably in the last ten years. 相似文献
46.
Opazo-Navarrete Mauricio Burgos-Díaz César Soto-Cerda Braulio Barahona Tamara Anguita-Barrales Fresia Mosi-Roa Yohanna 《Plant foods for human nutrition (Dordrecht, Netherlands)》2021,76(4):523-532
Plant Foods for Human Nutrition - There is an increasing interest in consuming healthy foods motivated by the need of boosting the immune system naturally. In this sense, vegetables rich in... 相似文献
47.
T Wasmoen S Armiger-Luhman C Egan V Hall H J Chu L Chavez W Acree 《Veterinary immunology and immunopathology》1992,35(1-2):83-93
This study demonstrates the transmission of feline immunodeficiency virus (FIV) from infected queens to kittens in two separate litters. Queen 1 was infected by intravenous administration of FIV at 22 days prior to parturition. Two out of three kittens from the litter were found to be viremic at 10 weeks of age as detected by culture isolation and polymerase chain reaction detection of FIV DNA in peripheral blood mononuclear leukocytes. The third kitten remained aviremic through 40 weeks of age. Queen 2 was infected by subcutaneous administration of FIV 2 days prior to parturition. This litter also had two out of three kittens infected with FIV; however, viremia was not detected in one of the kittens until 21 weeks of age. Culture isolation was found to be superior to polymerase chain reaction for the early detection of FIV, and viremia was found to precede seroconversion by up to 4 weeks. Although all infected kittens have remained healthy, depressed CD4:CD8 lymphocyte ratios suggest that clinical disease may develop. This study suggests that FIV infection in cats may be a useful model system for the study of HIV transmission from mothers to infants. 相似文献
48.
Tamara Martin‐Gimnez Antonio M. Cruz Agustín Barragn Estefanía Montero Pedro G. Sanchez Guillermo Caballero Ignacio Corradini 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2019,33(6):2780-2785
Occipital condylar fractures (OCFs) causing delayed onset lower cranial nerve paralysis (LCNPs) are rare. We present a 7‐year‐old Friesian horse with delayed onset dysphagia caused by vagus nerve (CNX) paralysis and suspicion of glossopharyngeal nerve (CNIX) paralysis developed several days after a minor head injury. Endoscopic examination revealed right laryngeal hemiplegia and intermittent dorsal displacement of the soft palate. An area of submucosal hemorrhage and bulging was appreciated over the dorsal aspect of the medial compartment of the right guttural pouch. Radiological examination of the proximal cervical region showed rotation of the atlas and the presence of a large bone fragment dorsal to the guttural pouches. Occipital condyle fracture with delayed onset cranial nerve paralysis was diagnosed. Delayed onset cranial nerve paralysis causing dysphagia might be a distinguishable sign of OCF in horses. Delayed onset dysphagia after head injury should prompt equine clinicians to evaluate the condition of the atlanto‐occipital articulation and skull base. 相似文献
49.
Jenifer R. Gold Tamara L. Grubb Sherry Cox Lais Malavasi Nicholas L. Villarino 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2022,36(2):792
BackgroundThe repeated administration of high doses of gabapentin may provide better analgesia in horses than current clinical protocols.Hypothesis and ObjectivesAdministration of gabapentin at 40 and 120 mg/kg PO q 12 h for 14 days will not alter serum biochemistry findings or cause adverse effects. Our objectives were to evaluate the effect of gabapentin on serum biochemistry, physical examination, and plasma pharmacokinetics of gabapentin.AnimalsSix healthy adult mares.MethodsHorses received 40 and 120 mg/kg of gabapentin orally q 12 h for 14 days. Horses were examined and scored for ataxia and sedation daily. Serum biochemistry variables were analyzed before treatment and days 7 and 14 after gabapentin administration. Plasma disposition of gabapentin was evaluated after the first and last drug administration. Pharmacokinetic parameters were estimated using noncompartmental analysis.ResultsNo changes occurred in physiologic or biochemical variables. Median (range) maximal plasma gabapentin concentrations (μg/mL) after the last dose (day 15) were 7.6 (6.2‐11) and 22 (14‐33) for 40 mg/kg and 120 mg/kg doses respectively. Maximal concentration of gabapentin was reached within 1 hour after drug administration. Repeated administration of gabapentin resulted in a median (range) area under the curve (AUC0‐12 hours) last/first dose ratio of 1.5 (1.00‐2.63) and 2.92 (1.4‐3.8) for the 40 and 120 mg/kg regimens, respectively.Conclusion and Clinical ImportanceOur results suggest that horses tolerate gabapentin up to 120 mg/kg PO q 12 h for 14 days. The analgesic effect of the dosage regimens evaluated in our study warrants further research. 相似文献
50.
David Bruce Lewis Nancy B. Grimm Tamara K. Harms John D. Schade 《Landscape Ecology》2007,22(6):911-924
Nutrient dynamics in rivers affect biogeochemical fluxes from land to oceans and the atmosphere. Fluvial ecosystems are thus
important environments for understanding spatial variability in nutrient concentrations. At the San Pedro River in semi-arid
Arizona, USA, we investigated how variability in dissolved inorganic nitrogen (DIN) was regulated by subsystem type and hydrological
flowpaths. The three subsystems we compared were the riparian zone, parafluvial (gravel bar) zone, and surface stream. DIN
concentration was greater in the riparian zone than in the surface stream, suggesting that the riparian zone retains DIN and
is a source of N for the surface stream. Parafluvial zones were too variable to generalize how they regulate DIN. Our hypothesis
that subsystem type regulates DIN oxidation was too simple. The riparian and parafluvial zones host a mosaic of oxidizing
and reducing conditions, as they exhibited highly variable ammonium to nitrate (NH4+:NO3−) ratios. Surface stream DIN was dominated by NO3−. Along a subsurface flowpath in the riparian zone, we did not observe spatial covariation among the N forms and transformations
involved in mineralization. We also compared spatial variability in solute concentrations between flowpaths and non-flowpath
reference areas. Our mixed results suggest that spatial variability is regulated in part by flowpaths, but also by solute-specific
processing length along a flowpath. To understand the distribution of N in fluvial ecosystems, subsystem type and flowpaths
are readily discernable guides, but they should be coupled with other mechanistic factors such as biota and soil type. 相似文献