首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   89篇
  免费   4篇
林业   8篇
农学   2篇
  15篇
综合类   4篇
农作物   2篇
水产渔业   5篇
畜牧兽医   51篇
植物保护   6篇
  2022年   1篇
  2021年   5篇
  2020年   2篇
  2019年   2篇
  2016年   6篇
  2015年   4篇
  2014年   2篇
  2013年   9篇
  2012年   7篇
  2011年   8篇
  2010年   3篇
  2009年   4篇
  2008年   3篇
  2007年   4篇
  2006年   2篇
  2005年   6篇
  2004年   9篇
  2003年   2篇
  2002年   9篇
  2001年   1篇
  1997年   1篇
  1995年   1篇
  1992年   1篇
  1981年   1篇
排序方式: 共有93条查询结果,搜索用时 296 毫秒
41.
Longline surveys have been conducted in the Northwest Pacific Ocean from 2000 to 2014 using chartered commercial longline vessels. Each year, two cruises were conducted offshore of northeastern Japan from mid‐April to mid‐June. For each longline set during the surveys, onboard scientists collected detailed biological information about the species caught, such as the size and sex, and recorded the catch numbers for all species. Blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) have eurythermal distributions, but the application of a generalized additive model (GAM) showed that the sea surface temperatures (SSTs) at catch sites positive for shortfin mako were warmer than those for blue shark. On the basis of the GAM, the probabilities of occurrence of both sharks differed by size category: small sharks had a narrower SST range than that of large sharks. Most catches of both sharks were juveniles, and the nominal catch rate of blue shark was more than 10 times that of shortfin mako. The standardized catch per unit effort (CPUE) for both species was calculated using a generalized linear model (GLM) with negative binomial errors, or a delta‐lognormal GLM. The standardized CPUE for blue shark in the second quarter of the year peaked in the mid‐2000s and then decreased, but it has been increasing since 2012. The CPUE for shortfin mako in the second quarter generally increased, with fluctuations.  相似文献   
42.
A 31-month-old Japanese Black cow (Bos taurus) aborted at 5 months of gestation with no clinical symptoms. Histopathological examination of the placenta and fetus revealed severe necrotic placentitis associated with numerous irregular degenerative fungi and inflammatory cells. Regular filamentous fungi were also detected, without inflammatory response in the fetal digestive and respiratory organs. Both fungi had aleurioconidia and septa in the placenta and fetal organs and immunohistochemically stained with antibodies against Aspergillus spp. Aspergillus terreus was isolated from the fetal lung and abomasal contents as confirmed using mycological and molecular methods. This is the first immunohistochemical, morphological, and molecular identification of A. terreus in bovine placenta and aborted fetuses.  相似文献   
43.
To visualize water-conduction pathways in living trees, we introduced aqueous solutions of safranin and acid fuchsin into stems of Populus sieboldii Miquel. To examine the spread of each dye in the trees, we compared several techniques for preparing tissue for light microscopy. Acid fuchsin was distributed more rapidly and more widely than safranin, reflecting differences between the dye molecules in state of ionization. We prepared some sections without allowing the dye to redissolve after it had been stabilized by freeze-drying. In these sections, the dye was observed in vessels and in some of the adjacent ray parenchyma cells. Other sections were prepared without stabilizing the dye. In these sections, acid fuchsin in the sap stream left cell walls unstained, whereas safranin stained wood fibers in the vicinity of vessels, as well as the vessels themselves, provided that the sections were mounted in glycerin, which dissolves safranin. Although stained with safranin, the wood fibers contained no water. The results indicate that stabilization of the introduced dye and subsequent preparation of tissues under conditions that avoid dye resolublilization allow accurate visualization of water-conduction pathways at the cellular level.  相似文献   
44.
The present study investigated the influence of a diet largely comprising rice whole‐crop silage (rWCS) on growth performance, carcass and meat characteristics, and expression of genes involved in muscle growth of Japanese Black steers. Steers were randomly separated into rWCS‐fed (rWCS ad libitum and restricted feeding of concentrate) and concentrate‐fed groups. Total digestible nutrient intake and daily gain (DG) decreased in rWCS‐fed steers in comparison with concentrate‐fed steers, whereas dressed carcass weight and final body weight did not significantly differ between the groups. Decreases in drip loss in the muscle of rWCS‐fed steers may be caused by α‐tocopherol and β‐carotene in muscle. Feeding large amounts of rWCS to steers may maintain quantitative productivity of beef steers equally to a concentrate‐based diet, and improve the qualitative productivity. Results of gene expression suggest that activation of skeletal muscle growth in rWCS‐fed steers may occur at the late fattening period owing to a decrease in myostatin and increase in myosin heavy chain gene expression. Preadipocyte factor‐1 and myostatin genes may be strongly involved in the control of lipid accumulation. This rearing system would allow beef production to switch to rWCS‐based diets from concentrate‐based diets.  相似文献   
45.
We investigated the effect of a system for fattening steers combining grazing with feeding rice whole‐crop silage (rWCS) on growth performance, meat characteristics, and the expression of genes involved in skeletal muscle growth. Steers were randomly assigned to grazing or concentrate‐fed groups (CT). The grazing group (GZ) was fed rWCS after grazing until 16 months of age. The final body weight was the same in the two groups, but the dressed weight was lower in the GZ than in the CT. The beef color standard was higher in the GZ than in the CT. Although beef marbling did not differ between the two groups, there was less intramuscular fat and subcutaneous fat in the GZ than in the CT. The α‐tocopherol and β‐carotene contents in the muscle were higher in the GZ than in the CT. The GZ showed a lower daily gain (DG) during the grazing period, which may have resulted from decelerating skeletal muscle growth caused by the increased expression of genes encoding myostatin and atrogin‐1. However, the DG and feed efficiency of the GZ increased after grazing. The two groups exhibited a similar level of beef productivity.  相似文献   
46.
47.
In plants and animals, small peptide ligands that signal in cell-cell communication have been suggested to be a crucial component of development. A bioassay of single-cell transdifferentation demonstrates that a dodecapeptide with two hydroxyproline residues is the functional product of genes from the CLE family, which includes CLAVATA3 in Arabidopsis. The dodecapeptide suppresses xylem cell development at a concentration of 10(-11) M and promotes cell division. An application, corresponding to all 26 Arabidopsis CLE protein family members, of synthetic dodecapeptides reveals two counteracting signaling pathways involved in stem cell fate.  相似文献   
48.
Clinical findings, geographic locations, laboratory diagnoses, and culture isolation of Neorickettsia spp. in Potomac horse fever (PHF) cases diagnosed in Ontario between 2015 and 2019 are described. Forty-six confirmed PHF cases occurred from late June to early September. Of 41 horses admitted to the Ontario Veterinary College, 28 (68%) survived and 13 (32%) were euthanized due to poor prognosis or financial constraints. Most cases were in southern Ontario along the Canada-USA border. Blood and fecal samples from 43 suspect PHF cases were submitted to 2 laboratories for polymerase chain reaction (PCR) testing for Neorickettsia risticii. Agreement between both laboratories for detection of N. risticii DNA was excellent for feces [κ = 0.932, 95% confidence interval (CI): 0.80 to 1], and fair for blood samples (κ = 0.494, 95% CI: 0.13 to 0.85). Neorickettia spp. were isolated from 16 of 41 (39%) blood samples. DNA analysis confirmed 14 isolates were N. risticii and 2 were N. findlayensis, a novel species of Neorickettsia recently demonstrated to cause PHF.  相似文献   
49.
ABSTRACT: Neorickettsia risticii is the Gram-negative, obligate, and intracellular bacterial pathogen responsible for Potomac horse fever (PHF): an important acute systemic disease of horses. N. risticii surface proteins, critical for immune recognition, have not been thoroughly characterized. In this paper, we identified the 51-kDa antigen (P51) as a major surface-exposed outer membrane protein of older and contemporary strains of N. risticii through mass spectrometry of streptavidin-purified biotinylated surface-labeled proteins. Western blot analysis of sera from naturally-infected horses demonstrated universal and strong recognition of recombinant P51 over other Neorickettsia recombinant proteins. Comparisons of amino acid sequences for predicted secondary structures of P51, as well as Neorickettsia surface proteins 2 (Nsp2) and 3 (Nsp3) among N. risticii strains from horses with PHF during a 26-year period throughout the United States revealed that the majority of variations among strains were concentrated in regions predicted to be external loops of their β-barrel structures. Large insertions or deletions occurred within a tandem-repeat region in Ssa3. These data demonstrate patterns of geographical association for P51 and temporal associations for Nsp2, Nsp3, and Ssa3, indicating evolutionary trends for these Neorickettsia surface antigen genes. This study showed N. risticii surface protein population dynamics, providing groundwork for designing immunodiagnostic targets for PHF.  相似文献   
50.
The datasets of net ecosystem CO2 exchange (NEE) were acquired from 21 forests, 3 grasslands, and 3 croplands in the eastern part of Asia based on the eddy covariance measurements of the international joint program, CarboEastAsia. The program was conducted by three networks in Asia, ChinaFLUX, JapanFlux, and KoFlux, to quantify, synthesize, and understand the carbon budget of the eastern part of Asia. An intercomparison was conducted for NEE estimated by three gap-filling procedures adopted by ChinaFLUX, JapanFlux, and KoFlux to test the range of uncertainty in the estimation of NEE. The overall comparison indicated good agreement among the procedures in the seasonal patterns of NEE, although a bias was observed in dormant seasons depending on the different criteria of data screening. Based on the gap-filled datasets, the magnitude and seasonality of the carbon budget were compared among various biome types, phenology, and stress conditions throughout Asia. The annual values of gross primary production and ecosystem respiration were almost proportional to the annual air temperature. Forest management, including clear-cutting, plantation, and artificial drainage, was significant and obviously affected the annual carbon uptake within the forests. Agricultural management resulted in notable seasonal patterns in the crop sites. The dataset obtained from a variety of biome types would be an essential source of knowledge for ecosystem science as well as a valuable validation dataset for modeling and remote sensing to upscale the carbon budget estimations in Asia.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号