全文获取类型
收费全文 | 59篇 |
免费 | 7篇 |
专业分类
林业 | 3篇 |
农学 | 3篇 |
6篇 | |
综合类 | 9篇 |
农作物 | 3篇 |
畜牧兽医 | 39篇 |
园艺 | 2篇 |
植物保护 | 1篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1990年 | 1篇 |
1986年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1915年 | 1篇 |
1910年 | 1篇 |
排序方式: 共有66条查询结果,搜索用时 10 毫秒
41.
The use of bismuth-layered perovskite films for planar-type nonvolatile ferroelectric random-access memories requires films with spontaneous polarization normal to the plane of growth. Epitaxially twinned a axis-oriented La-substituted Bi4Ti3O12 (BLT) thin films whose spontaneous polarization is entirely along the film normal were grown by pulsed laser deposition on yttria-stabilized zirconia-buffered Si(100) substrates using SrRuO3 as bottom electrodes. Even though the (118) orientation competes with the (100) orientation, epitaxial films with almost pure (100) orientation were grown using very thin, strained SrRuO3 electrode layers and kinetic growth conditions, including high growth rates and high oxygen background pressures to facilitate oxygen incorporation into the growing film. Films with the a-axis orientation and having their polarization entirely along the direction normal to the film plane can achieve a remanent polarization of 32 microcoulombs per square centimeter. 相似文献
42.
Albrecht Hesse Jenni Hoffmann Helmut Orzekowsky Reto Neiger 《The Canadian veterinary journal. La revue veterinaire canadienne》2016,57(3):277-281
This study reports a retrospective evaluation of epidemiological data from cystine stones of dogs submitted to the Urinary Stone Analysis Center Bonn, Germany, over a period of 35 years. Of the 20 316 uroliths submitted from 1979 to 2013, 1760 were cystine stones. In total, 109 breeds were affected with 16 breeds having an odds ratio > 1.0. Most of the cystine uroliths were retrieved from male dogs, with only 19 female dogs (1.1%) being affected. Percentage of submitted cystine stones amongst all stones decreased significantly over 35 years from 38.9% to 4.4%. 相似文献
43.
Blood flow of the preovulatory follicle (POF) wall can be used as a predictor of the quality of POF. Our aim was to determine the correlation of blood flow of POF with the POF diameter, and intra‐follicular and plasma concentrations of Insulin‐like Growth Factor‐I (IGF‐1) and oestradiol in dairy buffalo. Nine Murrah buffalo subjected to an ovulation synchronization protocol (Ovsynch) were assessed on day 10 of the protocol for diameter and blood flow of POF, followed by the aspiration of follicle fluid. Prior to follicular aspiration, blood samples were obtained from jugular vein for estimation of IGF‐1 and oestradiol. The vascularity of POF was determined (Range: 250–967 pixel2) along with intra‐follicular and plasma concentration of IGF‐1 (Range: 9.3–31.8 ng/ml and 14.7–29.7 ng/ml respectively) and oestradiol (Range: 124.2–447.9 ng/ml and 0.25–1.05 ng/ml respectively). Diameter of the POF was weakly correlated (r = 0.21, p < 0.01) with blood flow to it. As compared to POF diameter, the blood flow of POF had greater positive correlation with intra‐follicular and plasma concentrations of hormones (IGF‐1 and oestradiol). A strong positive correlation was recorded between intra‐follicular IGF‐1 and oestradiol. Also, plasma concentrations of oestradiol and progesterone were negatively correlated In brief, assessment of the blood flow of the POF is a non‐invasive and reliable indicator of its functional competence as compared to the POF diameter. 相似文献
44.
Saulo PS Guerra Guilherme Oguri Marcelo S Denadai Maura ST Esperancini 《Southern Forests》2018,80(2):131-135
The increasing demand for renewable energy feedstock has raised interest in growing eucalypts for fuel wood production, which is achieved by establishing very dense plantations cut every 18–24 months. The high moisture content of fresh Eucalyptus may handicap cut-and-chip operations, and offers a unique opportunity for supply chains based on baling. Therefore, the Canadian-made BioBaler was tested in Brazil on a eucalypt energy plantation, as well as on the resprouts generated by a conventional pulpwood plantation after severe frost damage. The BioBaler coped well with both crops, achieving high productivity levels: 7.1 and 3.3 t h?1 in the energy plantation and the failed crop treatments, respectively. Harvesting cost was estimated at €13 t?1 and €26 t?1 for the energy plantation and the failed crop, respectively. Productivity and harvesting cost were comparable with those reported in previous studies conducted in other countries on similar crops. Productivity was directly proportional to field stocking. Future studies should test the machine on a wider range of work conditions and include bale extraction, storage, processing and transportation, in order to estimate an overall supply chain cost and allow direct comparison with alternative options. 相似文献
45.
The results of massively parallel three-dimensional molecular dynamics simulations of the perpendicular intersection of extended dislocations in copper are reported. The intersection process, which involves three of the four possible 111 glide planes in the face-centered cubic lattice, begins with junction formation, followed by unzipping, partial dislocation bowing, cutting, and, finally, unit jog formation. The investigation provides insights into this complex atomistic process, which is currently not accessible to experimental investigation. 相似文献
46.
The increasing appearance of rods (»Stäbchen«) being found in Heterobasidion annosum cultures was investigated. They proved to be neither bacterial impurities nor fomannosin but calcium oxalates. The number of rod-shaped crystals depended on the quality of the tap water taken for the culture medium and on genetical aspects. The importance of calciumoxalates being formed by H. annosum is discussed. 相似文献
47.
Irrigation agriculture is an ancient and widespread feature in regions where allogenic rivers flow through arid landscapes. This paper reports the results of sedimentological–pedological investigations in the Palpa Valley in the coastal desert of southern Peru where sediment-laden river water is used for irrigation. An adapted facies classification is used to deduce a generalised stratigraphical sequence of the valley bottom sediments. Chronological constraints from radiocarbon dating and archaeological finds are used to reconstruct sedimentation rates for fossil to recent irragric anthrosols. Actualistic case studies are used to quantify present-day irrigation sedimentation. The investigations result in a clarification of the sedimentological and geomorphic history of this valley and a quantification of irrigation-related sedimentation. Irragric anthrosols date back more than 3500 years and provide direct evidence for the beginning of irrigation agriculture in this region. It is concluded that: (i) the up to approximately 4 m thick fine-grained sediments in the Palpa Valley bottom totaling a volume of 21.4 Mio. m3 are a result of long-lasting human impact and have to be considered as artefacts of prehistoric and historic irrigation agriculture in the hyperarid coastal desert; (ii) the fine-grained sediments represent a geoarchive which holds information on the history of irrigation agriculture as well as information on possible natural disturbance by extreme fluvial events; (iii) the identification of irragric anthrosols has implications for archaeological and paleoenvironmental reconstructions. 相似文献
48.
Initial goat domestication is documented in the highlands of western Iran at 10,000 calibrated calendar years ago. Metrical analyses of patterns of sexual dimorphism in modern wild goat skeletons (Capra hircus aegagrus) allow sex-specific age curves to be computed for archaeofaunal assemblages. A distinct shift to selective harvesting of subadult males marks initial human management and the transition from hunting to herding of the species. Direct accelerator mass spectrometry radiocarbon dates on skeletal elements provide a tight temporal context for the transition. 相似文献
49.
Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) is a highly toxic contaminant produced in the manufacture of phenoxy herbicides. Despite its high TCDD content, soil from a contaminated area associated with a 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) manufacturing site in Newark, New Jersey, did not induce acute toxicity when administered to guinea pigs (the most sensitive species) by gavage. Analysis of liver samples demonstrated low bioavailability of TCDD from this soil. A comparative analysis of soils showed that Soxhlet extraction was necessary for the determination of TCDD on Newark soil, whereas solvent extraction was sufficient for soil from Times Beach, Missouri. The difference in the bioavailability of TCDD from these soils is correlated with TCDD extractability and may be related to the different compositions of the soils. 相似文献
50.
The yields of inflorescences, corms and cormlets, and inflorescence quality of winter gladioli were studied under varying illumination levels of 12 hour daylength extension ranging from 0 to 333 lux. The illumination level of the daylength extension for each plot depended on its distance from 2 tungsten halogen light sources mounted at 6 m above ground on poles spaced 8 m apart. The lamps were adjusted for wide beam distribution and aimed at points on the ground 8 m from the base of the poles.Inflorescence yield was increased by increasing the illumination level of daylength extension. The relationship between horizontal illumination level in lux (x) and number of inflorescences (y) was described byy=27.3?10.9 exp(?0.02x)Ninety-seven % of maximum inflorescence yield was obtained at a daylength extension illuminance of 144 lux, while 97% of the maximum number of florets per spike and the other flower quality characteristics were obtained at a daylength extension illumination level of approximately 100 lux. Ninety-seven % of the maximum number of days to flowering was approached at a daylength extension illuminance of 45 lux.There was no clear relationship between the illumination level of daylength extension and number and weight of new corms, or the average weight of each new corm. However, the weights of cormlets per plot and per new corm were higher from plants which received no daylength extension.The commercial application of tungsten halogen lamps to provide daylength extension for winter gladioli production is discussed. 相似文献