全文获取类型
收费全文 | 355篇 |
免费 | 20篇 |
专业分类
林业 | 7篇 |
农学 | 3篇 |
17篇 | |
综合类 | 52篇 |
农作物 | 8篇 |
水产渔业 | 16篇 |
畜牧兽医 | 257篇 |
园艺 | 5篇 |
植物保护 | 10篇 |
出版年
2023年 | 3篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 13篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 22篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 11篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1979年 | 5篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 6篇 |
1968年 | 6篇 |
1967年 | 7篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1941年 | 2篇 |
排序方式: 共有375条查询结果,搜索用时 15 毫秒
41.
Pain, particularly chronic pain, is an underestimated ailment in cats. Veterinarians tend to under-diagnose and under-treat pain in this aloof and stoic species. Until recently, there was only one analgesic (i.e., butorphanol) approved in the United States for use in cats; but many analgesics, particularly opioids, have been used extra-label for this purpose. Nonsteroidal antiinflammatory drugs (NSAIDs) have been used sparingly in cats because of safety concerns, which are less of an issue with the newer agents. Meloxicam is the only NSAID labeled for use in cats in the United States, but other agents are available in this country and are labeled for use in cats in other countries. 相似文献
42.
For many years American science in the late 19th century was regarded as an intellectual backwater. This view derived from the assumption that the health of American science at the time was equivalent to the condition of pure science, especially pure physics. However, a closer look reveals that there was considerable vitality in American scientific research, especially in the earth and life sciences. This vitality is explainable in part by the natural scientific resources of the American continent but also in part by the energy given science from religious impulses, social reformism, and practicality. Furthermore, contrary to recent assumptions, the federal government was a significant patron of American science. The portrait of American science circa 1880 advanced in this article suggests that the nation's scientific enterprise was characterized by pluralism of institutional support and motive and that such pluralism has historically been the normal mode. 相似文献
43.
Dairy Australia is the national service body for the Australian dairy industry. Its role is to help farmers adapt to a changing operating environment and achieve a profitable, sustainable dairy industry. Although the use of antibiotics in Australian agriculture is relatively low in global terms, Dairy Australia recognises important drivers for continuous improvement in antimicrobial stewardship (AMS). Dairy Australia’s first strategic priority is to support profitable farms. This priority has driven the development of a range of on‐farm change management programs in the animal health and welfare fields to optimise the unit cost of production and dairy cattle welfare. Dairy Australia’s third strategic priority is to further develop a ‘trusted dairy industry’. Previous and current work under these two strategies position the dairy industry favourably with respect to confronting the challenge of antimicrobial resistance (AMR) and supporting sound AMS with the guiding principle of ‘as little as possible, as much as necessary’. However, given an incomplete but ongoing threat of AMR, more work is needed. Supported by Dairy Australia, the dairy industry has developed an antimicrobial use strategy aligning with the Australian Animal Sector National AMR Plan 2018. 相似文献
44.
45.
The first genetic linkage map of macadamia (Macadamia integrifolia and M. tetraphylla) is presented. The map is based on 56 F1 progeny of cultivars ‘Keauhou’ and ‘A16’. Eighty-four percent of the 382 markers analysed segregated as Mendelian loci. The
two-way pseudo-testcross mapping strategy allowed construction of separate parental cultivar maps. Ninety bridging loci enabled
merging of these maps to produce a detailed genetic map of macadamia, 1100 cm in length and spanning 70–80% of the genome.
The combined map comprised 24 linkage groups with 265 framework markers: 259 markers from randomly amplified DNA fingerprinting
(RAF), five random amplified polymorphic DNA (RAPD), and one sequence-tagged microsatellite site (STMS). The RAF marker system
unexpectedly revealed 16 codominant markers, one of them a putative microsatellite locus and exhibiting four distinct alleles
in the cross. This molecular study is the most comprehensive examination to date of genetic loci of macadamia, and is a major
step towards developing marker-assisted selection for this crop.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
46.
The Creative Economies of Texas Metropolitan Regions: A Comparative Analysis Before,During, and After the Recession 下载免费PDF全文
With the exception of Austin, metropolitan regions in Texas are not commonly included in research and analysis concerning creative economies—attention is largely focused on either the traditional capitals of creative production, New York and Los Angeles, or emerging, secondary regions such as Austin and Seattle, Washington. This article utilizes an industrial approach to examine the creative economies of the four most populous metropolitan regions of Texas—Austin, Dallas‐Ft. Worth, Houston, and San Antonio—and detail their scale, scope, and change between 2005 and 2015. Results help establish the creative economies of the Dallas‐Ft. Worth, Houston, and San Antonio metropolitan regions in the existing stream of creative research and discussion, offer further perspective on the dynamics and strength of the Austin region's creative economy, and provide insight into how regional creative economies emerge in rapidly urbanizing regions during the digital era. Additionally, special attention is paid to how these four creative economies transformed during the recessionary period from 2007 to 2009. Results of that attention build on prior research which points to the recession having a varied influence on creative economies depending on trends in the broader regional economies that house them. 相似文献
47.
48.
49.
Effects of dietary arginine supplementation during gestation and lactation on the performance of lactating primiparous sows and nursing piglets 总被引:4,自引:0,他引:4
A 2 x 2 factorial arrangement of treatments in a randomized block design was used to determine the effects of dietary Arg supplementation during gestation and lactation on the lactation performance of 38 first-parity sows. At 30 d of gestation, pregnant gilts were allotted based on BW to 1 of 2 diets supplemented with 1% L-Arg.HCl or 1.7% L-Ala (isonitrogenous control). After farrowing, sows were further allotted based on BW within previous gestation treatment groups to 1 of 2 lactation diets supplemented with 1% L-Arg.HCl or 1.7% L-Ala (isonitrogenous control). All gestation diets contained 3.1 Mcal/kg and 12.2% CP (as is) and were fed 2 kg/d in 2 equally sized meals, whereas all lactation diets contained 3.2 Mcal/kg and 18.6% CP (as is) and were fed ad libitum. Litter size was standardized to 10 piglets by cross-fostering within 24 h postfarrowing. On a weekly basis, BW and backfat (BF) thickness of sows, as well as piglet BW were measured, and blood and milk samples were obtained from the sows. Number of days from weaning to estrus and ADFI were also recorded. There were no differences in BW, BF thickness, ADFI, or days until return to estrus among treatment groups. There was no effect of the gestation diet or a gestation x lactation diet interaction on any parameter measured. On d 7 of lactation, plasma concentrations of Arg and insulin in sows, as well as concentrations of most AA in milk, were greater (P < 0.05) in response to Arg supplementation during lactation compared with the control. Weight gain of piglets from sows fed the Arg-supplemented diet during lactation was greater between d 0 and 7 (P < 0.01) and between d 0 and 21 (P < 0.05) of lactation compared with piglets from sows fed the control diet. Collectively, results from this study indicate the potential beneficial effects of dietary Arg supplementation in improving the lactation performance of first-parity sows. 相似文献
50.