全文获取类型
收费全文 | 62篇 |
免费 | 1篇 |
专业分类
林业 | 1篇 |
农学 | 2篇 |
2篇 | |
综合类 | 19篇 |
农作物 | 1篇 |
水产渔业 | 2篇 |
畜牧兽医 | 35篇 |
园艺 | 1篇 |
出版年
2020年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 4篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 6篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1960年 | 1篇 |
1956年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有63条查询结果,搜索用时 875 毫秒
31.
To study the crystallography of Earth's lower mantle, techniques for measuring synchrotron x-ray diffraction from a laser-heated diamond anvil cell have been developed. Experiments on samples of (Mg, Fe)SiO(3) show that silicate perovskite maintains its orthorhombic symmetry at 38 gigapascals and 1850 kelvin. Measurements at 65 and 70 gigapascals provide evidence for a temperature-induced orthorhombic-to-cubic phase transition and dissociation to an assemblage of perovskite and mixed oxides. If these phase transitions occur in Earth, they will require a significant change in mineralogical models of the lower mantle. 相似文献
32.
Enhanced metabolism of Leishmania donovani amastigotes at acid pH: an adaptation for intracellular growth 总被引:11,自引:0,他引:11
Amastigotes (tissue forms) of Leishmania donovani isolated from infected hamster spleens carried out several physiological activities (respiration, catabolism of energy substrates, and incorporation of precursors into macromolecules) optimally at pH 4.0 to 5.5. All metabolic activities that were examined decreased sharply above the optimal pH. Promastigotes (culture forms), on the other hand, carried out the same metabolic activities optimally at or near neutral pH. This adaptation to an acid environment may account in part for the unusual ability of amastigotes to survive and multiply within the acidic environment of the phagolysosomes in vivo. 相似文献
33.
34.
Dwyer RM Garber LP Traub-Dargatz JL Meade BJ Powell D Pavlick MP Kane AJ 《Journal of the American Veterinary Medical Association》2003,222(5):613-619
OBJECTIVE: To identify factors associated with excessive proportions of early fetal losses associated with mare reproductive loss syndrome in central Kentucky during 2001. DESIGN: Case-control study. PROCEDURE: Questionnaires were used to collect information on farm-, pasture-, and individual animal-level factors purportedly associated with mare reproductive loss syndrome. Data were collected for 133 farms (97 with excessive proportions of early feta losses and 36 control farms) representing 6,576 mares. RESULTS: Factors significantly associated with an increased risk of excessive early fetal losses were exposure to moderate to high concentrations of Eastern tent caterpillars, exposure to cherry trees, farm size > or = 50 broodmares, being bred during February 2001, and frequent exposure to waterfowl. Feeding hay to mares outside was associated with a decreased risk of excessive proportions of early fetal losses. Pasture composition and management factors were not significantly different between affected and control pastures. Individual animal-level factors were investigated on 6 farms representing 340 mares, and age, parity, and pre- and postbreeding treatments were not significantly associated with risk of early fetal loss. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that limiting exposure to Eastern tent caterpillars and cherry trees and feeding hay to mares outside may help decrease the risk of excessive proportions of early fetal losses associated with mare reproductive loss syndrome. 相似文献
35.
H. Sumano I. Gracia A. Capistrán G. Meade A. Rivero L. Ruiz‐Ramírez 《British poultry science》1995,36(3):503-507
1. Ambroxol and bromhexine were evaluated as mucolytics and to enhance the passage of furaltadone into tracheobronchial secretions (TBS) in chronic complicated respiratory disease‐affected broilers.
2. Viscosity of TBS was noticeably increased in the ambroxol‐treated birds and only slightly increased in the bromhexine groups; however, the physical (nature) of TBS was superior in the ambroxol‐treated broilers.
3. There was a clear increase in the passage of furaltadone into tracheobronchial secretions only in the ambroxol‐treated birds.
4. Everyday use of ambroxol in broilers is discussed. 相似文献
36.
Mounir Adnane Kieran G. Meade Cliona O’Farrelly 《Veterinary research communications》2018,42(4):255-263
Cervico-vaginal mucus (CVM), the product of epithelial cells lining the uterus, cervix and vagina, is secreted to facilitate uterine lubrication and microbial clearance. Predominantly composed of water and mucins, CVM also contains high levels of immuno-active proteins such as immunoglobulin A (IgA), lactoferrin and lysozyme which protect against infection by blocking adhesion and mediating microbial killing. The repertoire of cytokines, chemokines and antimicrobial peptides is predominantly generated by the secretions of endometrial epithelial cells into the uterine lumen and concentrated in the CVM. The quantity and relative proportions of these inflammatory biomarkers are affected by diverse factors including the estrus cycle and health status of the animal and therefore potentially provide important diagnostic and prognostic indicators. We propose that measuring molecular signatures in bovine CVM could be a useful approach to identifying and monitoring genital tract pathologies in beef and dairy cows. 相似文献
37.
Sarah H. Mackintosh Susie J. Meade Jackie P. Healy Kevin H. Sutton Nigel G. Larsen Adam M. Squires Juliet A. Gerrard 《Journal of Cereal Science》2009
The proteins of wheat have a known propensity to aggregate into a variety of forms. We report here a novel nanostructure from wheat proteins, derived from a crude extract of high molecular weight glutenins. The structure was characterised by a significant thioflavin T (ThT) fluorescence and a fibrillar morphology by transmission electron microscopy (TEM). The ThT fluorescence and TEM data are suggestive of an amyloid structure, but the X-ray fibre diffraction data show a reflection pattern (4.02, 4.2–4.3, 4.6, 12.9, 19.3 and 38.7 Å) inconsistent with both the classic amyloid form and the previously described β-helix structure. The 4.6 Å reflection is consistent with that predicted for the amyloid inter-β-strand, and the absence of the inter-β-sheet distance at ≈10–11 Å is not unprecedented in amyloid-like structures. However, our observed X-ray reflection pattern has not been previously reported and suggests a novel wheat glutenin nanostructure. 相似文献
38.
For more than 50 years, observations of earthquakes to depths of 100 to 650 kilometers inside Earth have been enigmatic: at these depths, rocks are expected to deform by ductile flow rather than brittle fracturing or frictional sliding on fault surfaces. Laboratory experiments and detailed calculations of the pressures and temperatures in seismically active subduction zones indicate that this deep-focus seismicity could originate from dehydration and high-pressure structural instabilities occurring in the hydrated part of the lithosphere that sinks into the upper mantle. Thus, seismologists may be mapping the recirculation of water from the oceans back into the deep interior of our planet. 相似文献
39.
Shaughnessy RG Meade KG McGivney BA Allan B O'Farrelly C 《Veterinary immunology and immunopathology》2011,142(1-2):64-71
Campylobacter jejuni colonises the caecum of more than 90% of commercial chickens. Even though colonisation is asymptomatic, we hypothesised that it is mediated by activation of several biological pathways. We therefore used chicken-specific 20K oligonucleotide microarrays to examine global gene expression in C. jejuni-challenged birds. Microarray results demonstrate small but significant fold-changes in expression of 270 genes 20 h post-challenge, corresponding to a wide range of biological processes including cell growth, nutrient metabolism and immunological activity. Expression of NOX1 (2.3-fold) and VCAM1 (1.5-fold) were significantly increased in colonised birds (P<0.05), indicating oxidative burst and endothelial cell activation, respectively. Microarray results, supplemented by qRT-PCR analyses demonstrated increased TOPK (1.9-fold), IL17 (3.6-fold), IL21 (2.1-fold), IL7R (4-fold) and CTLA4 (2.5-fold) gene expression (P<0.05), which was suggestive of T cell mediated activity. Combined these results suggest that C. jejuni has nominal effects on global caecal gene expression in the chicken but significant changes detected are suggestive of a protective intestinal T cell response. 相似文献
40.