全文获取类型
收费全文 | 1070篇 |
免费 | 130篇 |
专业分类
林业 | 41篇 |
农学 | 29篇 |
基础科学 | 3篇 |
137篇 | |
综合类 | 74篇 |
农作物 | 53篇 |
水产渔业 | 72篇 |
畜牧兽医 | 730篇 |
园艺 | 20篇 |
植物保护 | 41篇 |
出版年
2021年 | 15篇 |
2020年 | 16篇 |
2019年 | 27篇 |
2018年 | 21篇 |
2017年 | 27篇 |
2016年 | 35篇 |
2015年 | 17篇 |
2014年 | 36篇 |
2013年 | 61篇 |
2012年 | 55篇 |
2011年 | 52篇 |
2010年 | 27篇 |
2009年 | 23篇 |
2008年 | 47篇 |
2007年 | 46篇 |
2006年 | 34篇 |
2005年 | 28篇 |
2004年 | 50篇 |
2003年 | 45篇 |
2002年 | 40篇 |
2001年 | 42篇 |
2000年 | 35篇 |
1999年 | 30篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 16篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 12篇 |
1974年 | 17篇 |
1973年 | 12篇 |
1972年 | 11篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 9篇 |
1967年 | 9篇 |
1966年 | 11篇 |
排序方式: 共有1200条查询结果,搜索用时 15 毫秒
181.
Anders Kjær Glenn Nielsen Søren Stærke Morten Rahr Clausen Merete Edelenbos Bjarke Jørgensen 《Potato Research》2016,59(4):357-374
Handling and processing of potatoes is performed in increasingly large and more automated facilities, and the industry calls for more automated machinery for quality assessment and sorting by concentration of starch, soluble sugars, protein, amino acids etc. of the potato tubers. The present study was designed to evaluate five different scanning methods for their potential use in potato assessment and sorting. Two methods were based on hyperspectral imaging, two were based on dielectric/bio-impedance and one was based on low-field nuclear magnetic resonance. A set of 60 potatoes of 10 different cultivars were simultaneously sampled for analyses of content and scanned by the five different scanning methods. The resulting multivariate dataset was used to estimate the prediction ability of the individual scanning methods on starch-related parameters, selected simple sugars, selected amino acids, conductivity of pressed cell sap and cell sizes. Results showed that most types of spectral analyses had relatively high potential for predicting the starch-related parameters and medium potential for predicting the concentration of the reducing sugars fructose and glucose. Most methods showed medium potential for prediction of several amino acids, including asparagine, which showed particularly promising predictions in the hyperspectral analyses of intact potatoes. The presented screening study enabled us to perform robust choices for the further development and optimization of the methods and instruments for industrial implementation. 相似文献
182.
Chalcocite Oxidation and Coupled Carbon Dioxide Fixation by Thiobacillus ferrooxidans 总被引:1,自引:0,他引:1
The reaction of cell suspensions of Thiobacillus ferrooxidans with pulverized chalcocite (Cu(2)S) in a Warburg manometric apparatus resulted in oxygen uptake accompanied by increased solubilization of copper and fixation of carbon dioxide. Since the only detectable oxidized products were cupric ions and the more oxidized form of the sulfide mineral, that is, digenite or covellite, the apparent source of energy for the carbon dioxide fixation was provided by the oxidation of the cuprous copper of the chalcocite. 相似文献
183.
Summary A simple assay for detection of tobacco rattle virus in infected tubers involving RT-PCR was developed. The assay detected
a wide range of strains, including nonparticle NM variants. RNA extraction methods were compared, and a simple method was
found to give reliable results. The method enabled detection of at least 1 ng of tobacco rattle particles in 100 mg tuber
extract. 相似文献
184.
Recommendations for designing and conducting veterinary clinical pathology biologic variation studies 下载免费PDF全文
Kathleen P. Freeman Randolph M. Baral Navneet K. Dhand Søren Saxmose Nielsen Asger L. Jensen 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2017,46(2):211-220
The recent creation of a veterinary clinical pathology biologic variation website has highlighted the need to provide recommendations for future studies of biologic variation in animals in order to help standardize and improve the quality of published information and to facilitate review and selection of publications as standard references. The following recommendations are provided in the format and order commonly found in veterinary publications. A checklist is provided to aid in planning, implementing, and evaluating veterinary studies on biologic variation (Appendix S1 ). These recommendations provide a valuable resource for clinicians, laboratorians, and researchers interested in conducting studies of biologic variation and in determining the quality of studies of biologic variation in veterinary laboratory testing. 相似文献
185.
Paratuberculosis (Johne's disease) has been widespread in Danish dairy herds for a long time but the herd-level prevalence has never been determined precisely. To evaluate the prevalence of paratuberculosis in Danish dairy herds in various regions, an ELISA based on a commercially available antigen was adapted for testing bulk-tank milk for the presence of antibodies to Mycobacterium avium subsp. paratuberculosis. Bulk-tank milk samples were collected from six milk-collecting centres from six different areas of the country. Samples from 900 herds (about 7.5% of all Danish dairy herds) were examined, and 70% were positive at the statistically optimal cut-off (sensitivity 97.1%; specificity 83.3%). The technical performance of the ELISA was not sufficient to provide a tool for surveillance because even slight changes in optical density for the samples would change the classification of some samples. The infection is more widespread than previous investigations have shown. 相似文献
186.
187.
188.
The problems addressed are: (1) comparison of prevalences of Salmonella spp. in different herd types in the Danish pig population after implementation of the Danish Salmonella Control Program (DSCP), and (2) to make a reference to a study from 1993/1994 (pre-implementation) with a discussion of possible biases when diagnostic methods differ slightly. The objectives were to present the prevalences of Salmonella spp., Salmonella Typhimurium, and multiresistant S. Typhimurium DT104 in Danish pig herds in 1998. Further, to discuss how herd prevalences may be compared to a previous study.A bacteriological study in 1998 comprised: (a) a random sample of slaughter pig producing herds (N=1962); (b) a random sample of farrow-to-grower (sow) herds (N=305); and (c) all breeding and multiplying (genetic) herds (N=366). A previous bacteriological study on Salmonella presence in 1993/1994 served as a model for the present study. The results of the study were that multiresistant S. Typhimurium DT104 was detected in one herd producing slaughter pigs. The herd apparent prevalences (HAPs) of Salmonella spp. were 11.7, 16.7 and 11.4% in genetic, sow, and slaughter pig herds, respectively. The conclusion of the study was that prevalence of multiresistant S. Typhimurium DT104 was low in the examined slaughter pig herds. The herd true prevalence (HTP) of Salmonella spp. in pigs had declined from before the start of the DSCP in 1993/1994 to 4 years later (1998). 相似文献
189.
190.
Haemophilus pleuropneumoniae (Actinobacillus pleuropneumoniae). Serotypes 8, 3 and 6. Serological response and cross immunity in pigs 总被引:6,自引:0,他引:6
R Nielsen 《Nordisk veterinaermedicin》1985,37(4):217-227
Immunity obtained by vaccination with Haemophilus pleuropneumoniae is type specific and protection will only be obtained against the serotype contained in the vaccine. Serotype 8 is closely related to serotypes 3 and 6 and the objective of the present study was therefore to examine if cross immunity between the three serotypes could be obtained at vaccination. 相似文献