全文获取类型
收费全文 | 222篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
林业 | 8篇 |
农学 | 4篇 |
基础科学 | 2篇 |
18篇 | |
综合类 | 29篇 |
农作物 | 11篇 |
水产渔业 | 12篇 |
畜牧兽医 | 153篇 |
园艺 | 5篇 |
植物保护 | 4篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 19篇 |
2012年 | 4篇 |
2011年 | 9篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 14篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1952年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有246条查询结果,搜索用时 15 毫秒
151.
Ectopic pro-opiolipomelanocortin: sequence of cDNA coding for beta-melanocyte-stimulating hormone and beta-endorphin 总被引:4,自引:0,他引:4
C R DeBold M E Schworer T B Connor R E Bird D N Orth 《Science (New York, N.Y.)》1983,220(4598):721-723
A recombinant bacterial plasmid, pMS1, was constructed that contains 318 nucleotides complementary to a portion of pro-opiolipomelanocortin (proOLMC) messenger RNA from an ectopic adrenocorticotropin-producing tumor. The cloned complementary DNA insert, which contains the sequence that codes for all of the beta-melanocyte-stimulating hormone and beta-endorphin portions of proOLMC, as well as the 3' nontranslated section, is identical to the genomic sequence. Hybridization of tumor proOLMC complementary DNA to RNA subjected to electrophoresis and transferred to a nitrocellulose filter revealed two proOLMC messenger RNA species in the tumor polyadenylated RNA, but only one in pituitary polyadenylated RNA. At least one of the tumor proOLMC messenger RNA's is similar, if not identical, to human pituitary proOLMC messenger RNA. 相似文献
152.
Pollen-handling protocol and hydration/dehydration characteristics of pollen for application to long-term storage 总被引:1,自引:0,他引:1
Summary The National Seed Storage Laboratory in Fort Collins, Colorado, is investigating pollen storage as a practical means for storing germplasm of clonally-held species. Careful regulation of pollen moisture content is necessary to safely store pollens and perform accurate in vitro germination tests. A series of dehydration and hydration curves were generated for Pinus ponderosa Dough. ex P. Laws., Picea pungens Engelm., and Carya illinoensis (Wangenh.) K. Koch pollens using five saturated salt solutions and water. Equilibrium moisture contents (EMCs) were also determined for Typha latifolia L., Phoenix dactylifera L., Corylus avellana L., and Zea mays L. Although rates of dehydration and hydration, and EMC varied with salt, pollen, and temperature, the pollens tested did survive the drying procedures and could successfully be stored in liquid nitrogen.Abbreviations NSSL -
National Seed Storage Laboratory
- EMC -
Equilibrium Moisture Content
- LN -
Liquid Nitrogen 相似文献
153.
Observational studies are common in veterinary medicine; the results may be used to inform decision-making, future research, or as inputs to systematic reviews or risk assessment. To be of use, the results must be published, all of the outcomes that were assessed must be included in the publication, and the research (methods and results) must be reported in sufficient detail that the reader can evaluate the internal and external validity. In human healthcare, concerns about the completeness of reporting – and evidence that poor reporting is associated with study results – have led to the creation of reporting guidelines; these include the STROBE statement for observational studies. 相似文献
154.
Hilary M. Clayton Katherine A. O’Connor LeeAnn J. Kaiser 《Veterinary journal (London, England : 1997)》2014,199(1):44-48
The objective of this study was to compare forces and pressure profiles beneath a conventional dressage saddle with a beechwood spring tree and a treeless dressage saddle without a rigid internal support and incorporating large panels and a gullet. The null hypothesis was that there is no difference in the force and pressure variables for the two saddles. Six horses were ridden by the same rider using the conventional dressage saddle and the treeless dressage saddle in random order and pressure data were recorded using an electronic pressure mat as the horses trotted in a straight line. The data strings were divided into strides with ten strides analyzed per horse–saddle combination. Variables describing the loaded area, total force, force distribution and pressure distribution were calculated and compared between saddles using a three-factor ANOVA (P < 0.05).Contact area and force variables did not differ between saddles but maximal pressure, mean pressure and area with pressure >11 kPa were higher for the treeless dressage saddle. The panels of the treeless dressage saddle provided contact area and force distribution comparable to a conventional treed saddle but high pressure areas were a consequence of a narrow gullet and highly-sloped panels. It was concluded that, even with a treeless saddle, the size, shape, angulation, and position of the panels must fit the individual horse. 相似文献
155.
Land-based recycling of processed sewage sludge (biosolids) has traditionally been challenged by concerns over metals, organics, pathogens, odors, and public perception. Nutrient concerns, however, portend even greater challenges, and threaten land application programs in the US. Long-term application of biosolids results in accumulation of soil phosphorus (P) above concentrations needed for optimum crop yields. Water quality impairment associated with accelerated eutrophication is driving the US states to adopt policies and laws to reduce P losses to surface waters from agricultural land. Nearly all states have developed site assessment tools (P indices) to rank fields based on their vulnerability to P loss and to target remedial strategies. Biosolids have not been systematically addressed in most states and sustaining economical biosolids recycling programs will be difficult if policies fail to consider certain critical issues. Soil test P benchmarks should be based upon environmental P loss risk rather than crop response. Policies must recognize the role of mandated buffers in protecting surface water quality. Site indices must account for the sizable differences in P loss potential among biosolids types compared to mineral fertilizers and livestock manures. Finally, agronomic rate calculations must recognize different P fertilizer replacement values among biosolids products. Deployment of P management regulations for biosolids lacking scientifically defensible strategies in these areas will adversely affect land-based recycling. Sustainability requires additional research and intentional inclusion of biosolids in implementation of evolving P management policies. 相似文献
156.
Pondberry (Lindera melissifolia [Walt.] Blume: Lauraceae) is an endangered, dioecious, clonal shrub that grows in bottomland hardwood forests in the southeastern United States. Prior work has emphasized vegetative reproduction associated with the clonal nature of this species. Little has been published about the early morphological and biochemical characteristics of the fruit as they mature. Fruits, drupes originating from the axillary buds, were collected every 30 days after anthesis and examined for seed structure development and fatty acid composition of the fruit and seed. Sixty days after anthesis, fruits had not formed an organized embryo/cotyledon, weighed 0.1 ± 0.001 g, and measured 7.1 ± 0.04 mm × 4.3 ± 0.03 mm. Ninety days after anthesis, a complete seed had formed within the drupe. Of the total drupe weight (average 0.23 ± 0.01 g), the seed comprised 33% of the mass gained from 60 days after anthesis. Overall composition of the seed and pulp lipids changed significantly over the course of development. Myristic, palmitic, steric, oleic, linoleic, and linolenic fatty acids were revealed by the lipid analyses. Lauric acid was not found in any of the early seed lipid samples but it increased in quantity as seed matured to become the dominant fatty acid in this tissue. Conversely, pulp contained only small amounts of lauric acid; its fatty acid profile was dominated by oleic acid. Fully hydrated seeds stored well for 16 months at both 4 °C and −2 °C. Although drying had a deleterious effect on germination when dried seeds were conventionally stored at 4 °C, seeds that had been dried for 24 h to a moisture content of 8.6% were successfully stored in liquid nitrogen. 相似文献
157.
Brian Roy Lockhart Emile S. Gardiner Theodor D. Leininger Kristina F. Connor Margaret S. Devall Paul B. Hamel Tracy Hawkins Nathan M. Schiff A. Dan Wilson 《Forest Policy and Economics》2009,11(8):539-547
The need for knowledge, ranging from development of new products or processes to the effects of specific actions on the environment, is greater now than at any point in the past. The greater need for research has generated stakeholder involvement in the research process. As a result, all facets of research, from planning through publication of results, are often scrutinized by stakeholders. While the basic nature of scientific inquiry has not changed, now more than ever the credibility of scientific results is based on thorough planning, peer reviews of experimental designs and analytical approaches, and assurance that data are of the highest quality. Public interest in the quality and accuracy of federal research rose to a level that resulted in the Data Quality Act of 2001. The Act required the establishment of guidelines for Federal research organizations and cooperators. We present a case study of the U. S. Forest Service's policies for research quality assurance and quality control, including developing quality assurance statements and plans, as applied to comprehensive research on the federally-listed, endangered forest shrub pondberry (Lindera melissifolia (Walt.) Blume). 相似文献
158.
N J Lewis A H Fallah-Rad M L Connor 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(8):496-498
Fourteen Suffolk rams (6 mo) were diagnosed with chronic copper poisoning. Preliminary results indicated that a combination of serum aspartate aminotransferase, gamma glutamyltransferase, and copper could be used as a test so that high risk lambs could be treated more aggressively. 相似文献
159.
Isolation of an avirulent influenza virus from a parrot 总被引:1,自引:0,他引:1
160.