全文获取类型
收费全文 | 124篇 |
免费 | 6篇 |
专业分类
林业 | 7篇 |
农学 | 3篇 |
基础科学 | 2篇 |
9篇 | |
综合类 | 35篇 |
农作物 | 1篇 |
水产渔业 | 7篇 |
畜牧兽医 | 57篇 |
园艺 | 1篇 |
植物保护 | 8篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 3篇 |
1954年 | 1篇 |
1906年 | 1篇 |
1899年 | 1篇 |
1895年 | 1篇 |
排序方式: 共有130条查询结果,搜索用时 0 毫秒
1.
Andrews GA Smith JE Gray M Chavey PS Weeks BR 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1992,21(2):57-60
An improved serum ferritin assay for canine serum has been developed. It uses two monoclonal antibodies in a sandwich arrangement. Serum ferritin can be determined on undiluted canine sera with this assay. The recovery of ferritin added to canine serum ranged from 98 to 106%, the within-assay coefficient of variability was 3.3 to 4.5%, and the assay-to-assay variability was 9.8 to 10.2%. Serum ferritin from 61 apparently healthy dogs had a geometric mean of 252 ng/ml, with a range of 80 ng/ml to 800 ng/ml. 相似文献
2.
3.
近两年,我国木制家具出口可以说是超常规发展。2004年我国出口木制家具为129亿件,到了2005年,达到了1.49亿件,增幅高达16%;至2006年,尽管国际上欧美一些发达国家对我国家具出口“反倾销”和知识产权侵权诉讼接连不断,国内下半年又有国家出口退税率下调等显然不利于家具出口的政策出台,但所有这些内外在因素的合力,似乎都未能构成对我国家具出口大潮本质上的阻扼。 相似文献
4.
Chan F Barth JA Lubchenco J Kirincich A Weeks H Peterson WT Menge BA 《Science (New York, N.Y.)》2008,319(5865):920
Eastern boundary current systems are among the world's most productive large marine ecosystems. Because upwelling currents transport nutrient-rich but oxygen-depleted water onto shallow seas, large expanses of productive continental shelves can be vulnerable to the risk of extreme low-oxygen events. Here, we report the novel rise of water-column shelf anoxia in the northern California Current system, a large marine ecosystem with no previous record of such extreme oxygen deficits. The expansion of anoxia highlights the potential for rapid and discontinuous ecosystem change in productive coastal systems that sustain a major portion of the world's fisheries. 相似文献
5.
Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent nature gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occur offshore beneath the shallow, ice-covered seas, of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas. 相似文献
6.
7.
8.
Fragments of the HIV-1 Tat protein specifically bind TAR RNA 总被引:75,自引:0,他引:75
K M Weeks C Ampe S C Schultz T A Steitz D M Crothers 《Science (New York, N.Y.)》1990,249(4974):1281-1285
Proteolytically produced carboxyl-terminal fragments of the human immunodeficiency virus type-1 (HIV-1) Tat protein that include a conserved region rich in arginine and lysine bind specifically to transactivation response RNA sequences (TAR). A chemically synthesized 14-residue peptide spanning the basic subdomain also recognizes TAR, identifying this subdomain as central for RNA interaction. TAR RNA forms a stable hairpin that includes a six-residue loop, a trinucleotide pyrimidine bulge, and extensive duplex structure. Competition and interference experiments show that the Tat-derived fragments bind to double-stranded RNA and interact specifically at the pyrimidine bulge and adjacent duplex of TAR. 相似文献
9.
The movements of cattle at 12 livestock auction markets were observed to determine the possible causes of trauma leading to carcase bruising. Design faults included right-angled bends in races, dead ends, flooring with insufficient slope or grip, and steps. Sliding gates were often misused for goading cattle. Projecting fittings and square-edged corners were potentially injurious; conversely, rounded posts and curved races assisted the flow of cattle with minimal impacts. At all the markets, some cattle were hit directly and poked with wooden sticks, and the variations in their use could partially explain the differences between the markets in the prevalence of carcase bruising. Most harder hits were directed at less valuable parts of the body, such as the spine, hips and shoulders, and a survey of bruising at the abattoir showed that these were the areas with most bruising. In this survey of 48,926 carcases, the overall level of commercially significant bruising of 4.1 per cent was lower than the 6.5 per cent found in a previous survey. Carcases of cattle from markets had a greater incidence and severity of bruising (P<0.001) than those arriving directly from farms or dealers. Carcase bruising in young bulls was less (P<0.001) than in heifers and steers. 相似文献
10.
The chemotactic and phagocytic efficiencies of macrophages from spot, Leiostomus xanthurus and hogchoker, Trinectes maculatus are reported here. Fish were captured from the York and Ware Rivers, two relatively nonpolluted rivers, and from a reach of the Elizabeth River, known to be contaminated with high concentrations of polynuclear aromatic hydrocarbons (PAHs). Kidney cell types were separated by density gradient centrifugation and single cell suspensions of macrophages were used for in vitro studies. Chemotactic activity was measured in Boyden chambers using Escherichia coli as the chemotactic stimulus. The percentage of macrophages migrating was maximal at 90 min but was markedly reduced in Elizabeth River fish (spot, 33%; hogchoker, 56%) as compared to clean water controls (spot, 55%; hogchoker, 85%). Macrophage phagocytosis of bacteria was quantified by the microscopic enumeration of the proportion of phagocytes which contained intracellular bacteria. Phagocytic activity reached maximum values within 120 min and remained relatively constant for the remainder of the experiment. Phagocytic activity was reduced significantly in the fish obtained from the Elizabeth River. Values at 120 min were 74% and 19% for spot from the control and PAH-contaminated sites, respectively. Comparable values for hogchoker were 88% and 32%. The results suggest that defective macrophage function is related to exposure to PAH-contaminated sediments. 相似文献