全文获取类型
收费全文 | 309篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
林业 | 37篇 |
农学 | 10篇 |
基础科学 | 1篇 |
62篇 | |
综合类 | 21篇 |
农作物 | 23篇 |
水产渔业 | 18篇 |
畜牧兽医 | 115篇 |
园艺 | 7篇 |
植物保护 | 36篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 9篇 |
2013年 | 17篇 |
2012年 | 19篇 |
2011年 | 36篇 |
2010年 | 21篇 |
2009年 | 8篇 |
2008年 | 21篇 |
2007年 | 18篇 |
2006年 | 15篇 |
2005年 | 12篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1988年 | 1篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1963年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有330条查询结果,搜索用时 31 毫秒
321.
Enrico Bigliardi Carla Bresciani Daniela Callegari Francesco Di Ianni Giorgio Morini Enrico Parmigiani Ezio Bianchi 《Journal of veterinary science (Suw?n-si, Korea)》2014,15(2):267-271
Insulin resistance (IR) in dogs is suspected when hyperglycemia is present despite administration of insulin doses greater than 1.0 to 1.5 UI/kg. IR is caused by increases in counter regulatory hormones concentrations (glucagon, glucocorticoids, catecholamines and growth hormone). This study was conducted to investigate the use of aglepristone (RU 46534), a P4 receptor antagonist, for the treatment of IR diabetes mellitus in bitches during the luteal phase. All animals were treated with porcine insulin zinc suspension (Caninsulin) and aglepristone (Alizin) 10 mg/kg subcutaneously at day 1, 2, 9 and 17 from diagnosis. At day 5, no significant variation in glycemia was shown. At day 12 and 20, serum glucose concentrations were significant lower (p < 0.05). From day 12 the insulin dose was reduced to 0.8 IU BID. Insulin was reduced in the following weeks and glycemia was controlled. 相似文献
322.
Elena Tamburini Alicia Gordillo León Brunella Perito Mario Di Candilo Giorgio Mastromei 《Euphytica》2004,140(1-2):47-54
Summary Retting is the major limitation to an efficient production of textile hemp fibres. Traditional retting has been carried out by autochthonous bacterial community. Aerobic and anaerobic pectinolytic strains were isolated from hemp or flax sources and characterised. Anaerobic pectinolytic strains had a wide range of acid polygalacturonase (PG) activity, whereas aerobic isolates did not produce any acid PG activity, but only an alkalophylic one, suggesting they could play a minor role in the retting process, except in the early stages. Analysis of 16S rDNA sequences assigned anaerobic strains to the Clostridium genus and aerobic isolates to the Bacillus and Paenibacillus genus. C. felsineum and C. acetobutylicum were confirmed as the main anaerobic agents. Nevertheless, a high proportion of anaerobic and aerobic pectinolytic strains was assigned to C. saccharobutylicum and B. pumilus, respectively, both species never being described as involved in water retting. Anaerobic and aerobic strains with high PG activity were selected and characterized. PG activity is well correlated with the strain retting efficiency and improvement of the process was obtained by inoculating the retting water with spores of selected aerobic and anaerobic bacteria. An advisable feature of retting strains is the absence of cellulosolytic activity. An aerobic strain with no cellulosolytic activity was identified. In contrast, all the anaerobic isolates showed cellulosolytic activity. Mutagenesis was ineffective for selection of Cel-Pec+ mutants. Localization of the C. felsineum L1/6 PG activity was investigated. 相似文献
323.
Camille N Coricelli G Sallet J Pradat-Diehl P Duhamel JR Sirigu A 《Science (New York, N.Y.)》2004,304(5674):1167-1170
Facing the consequence of a decision we made can trigger emotions like satisfaction, relief, or regret, which reflect our assessment of what was gained as compared to what would have been gained by making a different decision. These emotions are mediated by a cognitive process known as counterfactual thinking. By manipulating a simple gambling task, we characterized a subject's choices in terms of their anticipated and actual emotional impact. Normal subjects reported emotional responses consistent with counterfactual thinking; they chose to minimize future regret and learned from their emotional experience. Patients with orbitofrontal cortical lesions, however, did not report regret or anticipate negative consequences of their choices. The orbitofrontal cortex has a fundamental role in mediating the experience of regret. 相似文献
324.
Ventura M Antonacci F Cardone MF Stanyon R D'Addabbo P Cellamare A Sprague LJ Eichler EE Archidiacono N Rocchi M 《Science (New York, N.Y.)》2007,316(5822):243-246
A systematic fluorescence in situ hybridization comparison of macaque and human synteny organization disclosed five additional macaque evolutionary new centromeres (ENCs) for a total of nine ENCs. To understand the dynamics of ENC formation and progression, we compared the ENC of macaque chromosome 4 with the human orthologous region, at 6q24.3, that conserves the ancestral genomic organization. A 250-kilobase segment was extensively duplicated around the macaque centromere. These duplications were strictly intrachromosomal. Our results suggest that novel centromeres may trigger only local duplication activity and that the absence of genes in the seeding region may have been important in ENC maintenance and progression. 相似文献
325.
Pathological findings associated with naturally acquired porcine circovirus type 2 associated disease 总被引:1,自引:0,他引:1
Porcine circovirus type 2 (PCV2) is a novel virus of the Circoviridae family which is considered the cause of postweaning multisystemic wasting syndrome (PMWS). PCV2 has also been associated to a number of pathological conditions of pigs, including porcine dermatitis and nephropathy syndrome, reproductive failure, porcine respiratory disease complex, proliferative and necrotising pneumonia and congenital tremor type AII. Pathological studies have been used to describe and characterise PMWS and these emerging conditions associated with PCV2. The objective of this review is to concentrate on the gross, microscopic and ultrastructural pathology associated with natural cases of PCV2 associated disease, along with some speculations on the pathogenesis of naturally occurring PMWS. 相似文献
326.
Prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) in an integrated swine production system experiencing postweaning multisystemic wasting syndrome 下载免费PDF全文
Lorenzo Fraile Maria Calsamiglia Enric Mateu Anna Espinal Anna Cuxart Chiara Seminati Marga Martín Mariano Domingo Joaquim Segalés 《Canadian journal of veterinary research》2009,73(4):308-312
The objective of this study was to evaluate the prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) through a longitudinal study in an integrated swine production system (7 farms) experiencing postweaning multisystemic wasting syndrome (PMWS). Risk factors for PCV-2 infection and for PCV-2 and PRRSV coinfection were also evaluated. Fifteen sows from each herd and 4 non-cross-fostered piglets from each sow were randomly selected at farrowing and ear-tagged at birth. Serum samples were analyzed for antibodies to PCV-2 and for detection of the PCV-2 and PRRSV genomes. Statistical analyses involved 2 approaches. The 1st approach characterized the dynamics of PCV-2 infection and their relationship with PRRSV infection. The 2nd approach analyzed the probability of being infected by PCV-2 or by both PCV-2 and PRRSV through a generalized linear mixed model incorporating sow and farm characteristics. At the 1st sampling time (1 wk of age), there was a significant relationship between sow PCV-2 infection and piglet PCV-2 infection (P < 0.0001). The risk of PCV-2 and PRRSV coinfection was 1.85 times greater in piglets from a sow with low titers of PCV-2 antibodies than in piglets from sows with medium to high titers (P = 0.03) and was 2.54, 2.40, and 2.02 times greater, respectively, in piglets from primiparous sows, PCV-2-infected sows, and farms in an area of high pig density than in piglets from sows of higher parity (P = 0.004), noninfected sows (P = 0.04), and farms in a low-density area (P = 0.09). 相似文献
327.
Fedrizzi B Magno F Badocco D Nicolini G Versini G 《Journal of agricultural and food chemistry》2007,55(26):10880-10887
Thirteen sulfur compounds (boiling points from 35 to 231 degrees C), usually considered as possible off-flavoring volatiles, were quantified by a concurrent headspace-solid phase microextraction method coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS) on 80 not off-flavoring wines of four varieties (Merlot, Marzemino, and Teroldego as red wines and Chardonnay as a white one) and of five vintages produced in the North Italian Trentino region. The results of the research, the first Italian data-bank per variety on such volatiles, allow us to make a comparison with the data of other winegrowing areas, to investigate the aging effect on the considered volatiles, and, finally, to try a variety discrimination using statistical procedures. Dimethyl sulfide, 3-(methylthio)-1-propanol, diethyl sulfide, and diethyl disulfide were found to increase with time whereas 2-mercaptoethanol and ethylmercaptan showed a decreasing trend. Furthermore, the concentration of several compounds was found to be dependent on the variety. For instance, sulfide, disulfides, benzothiazole, and thioalcohols are at higher levels in Merlot wines, whereas thiols and thioacetates are more abundant in Marzemino and Teroldego wines. Chardonnay products, well apart from the other wines, are the poorest in 3-(methylthio)-1-propanol and rather rich in dimethyl disulfide and in diethyl disulfide, mostly in the aged wines. Applying the principal component analysis to the data, it was possible to demonstrate that Chardonnay and Merlot wines are well-discriminated from the Italian native varietal wines, which on their turn are only partially distinguishable among them. A contribution of these compounds to the variety characteristics of wine is reasonable. 相似文献
328.
Paolo Guidetti Piero Addis Fabrizio Atzori Simona Bussotti Antonio Cal Alessandro Cau Jean‐Michel Culioli Giuseppe De Lucia Antonio Di Franco Manfredi Di Lorenzo Maria Cristina Follesa Vittorio Gazale Giorgio Massaro Francesco Mura Augusto Navone David Pala Pier Augusto Panzalis Antonio Pusceddu Alberto Ruiu Angelo Cau 《水产资源保护:海洋与淡水生态系统》2019,29(4):537-545
329.
Roberta Teta Germana Esposito Karishma Kundu Mariano Stornaiuolo Silvia Scarpato Antonino Pollio Valeria Costantino 《Marine drugs》2022,20(4)
In this study, a strain of Anabaena flos-aquae UTEX 1444 was cultivated in six different concentrations of iron (III). Cultures were extracted with organic solvents and analyzed using our dereplication strategy, based on the combined use of high-resolution tandem mass spectrometry and molecular networking. The analysis showed the presence of the siderophores’ family, named synechobactins, only in the zero iron (III) treatment culture. Seven unknown synechobactin variants were present in the extract, and their structures have been determined by a careful HRMS/MS analysis. This study unveils the capability of Anabaena flos-aquae UTEX 1444 to produce a large array of siderophores and may be a suitable model organism for a sustainable scale-up exploitation of such bioactive molecules, for the bioremediation of contaminated ecosystems, as well as in drug discovery. 相似文献
330.
María Victoria Vadell Carlos González Fischer Mariano Codesido Aníbal Carbajo David Bilenca Isabel E. Gómez Villafañe 《Zoonoses and public health》2023,70(1):13-21
Hantavirus pulmonary syndrome (HPS) is a zoonotic emerging infectious disease caused by New World orthohantaviruses (family Hantaviridae) hosted by rodents of the family Cricetidae. In Argentina, one of its main hosts is the sigmodontine rodent Oligoryzomys flavescens, a widely distributed mouse of the Pampas, Delta and Espinal ecoregions of central-east Argentina. Because the abundance of the reservoir and its proportion in the rodent community affects both virus prevalence and human exposure risk, its estimation throughout its known geographical distribution is of key importance for the design of public health strategies to prevent HPS. The aim of this study was therefore to model the relative abundance of O. flavescens in most of the Pampas ecoregion within Buenos Aires Province, Argentina, where hantavirus pulmonary syndrome is endemic. To do this we used owl-pellet samples collected between 2006 and 2008 from 51 sites distributed throughout most of Buenos Aires province. Mammalian prey in each pellet was identified to the lowest possible taxonomic level by examination of the skulls, dentaries and molars. We modelled the frequency of O. flavescens found in each sample as a function of climatic, environmental, and topographic data of each site. The two best models were applied to a Geo referential Information System to build maps of estimated frequency (as a proxy of relative abundance) within Buenos Aires province. Estimated relative abundance of O. flavescens in Buenos Aires province was significantly associated with annual mean temperature, annual precipitation and presence of freshwater bodies, and varied among sub-regions, with the Inland and Rolling Pampas being the regions with highest frequencies. Knowing in which areas O. flavescens abundance is expected to be higher can be used to concentrate limited sanitary efforts in those areas that are most needed in order to reduce transmission and increase detection. 相似文献