全文获取类型
收费全文 | 472篇 |
免费 | 9篇 |
专业分类
林业 | 51篇 |
农学 | 22篇 |
基础科学 | 6篇 |
127篇 | |
综合类 | 46篇 |
农作物 | 12篇 |
水产渔业 | 31篇 |
畜牧兽医 | 146篇 |
园艺 | 12篇 |
植物保护 | 28篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 16篇 |
2013年 | 20篇 |
2012年 | 38篇 |
2011年 | 41篇 |
2010年 | 20篇 |
2009年 | 21篇 |
2008年 | 46篇 |
2007年 | 37篇 |
2006年 | 32篇 |
2005年 | 25篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 28篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1967年 | 4篇 |
1956年 | 1篇 |
1940年 | 2篇 |
1936年 | 2篇 |
1934年 | 3篇 |
1933年 | 2篇 |
排序方式: 共有481条查询结果,搜索用时 15 毫秒
1.
Ohne Zusammenfassung 相似文献
2.
3.
Pille F Martens A Schouls LM Dewulf J Decostere A Vogelaers D Gasthuys F 《Veterinary journal (London, England : 1997)》2007,173(1):73-78
The objectives of the present study were to evaluate the accuracy of broad range 16S rRNA gene PCR compared to bacterial culture for the detection of synovial infection in horses. The study included 57 synovial fluid samples from horses with presumed synovial infection and a control group consisting of 31 synovial fluid samples originating from clinically normal horses and horses with aseptic synovial inflammation. All samples were analysed by 16S PCR with reverse line blot (RLB) hybridisation. Synovial fluid samples were cultured using conventional agar plate methods (APM) and/or blood culture medium (BCM). The results of the study showed a superior detection rate (89.5%) for 16S PCR with RLB. Bacterial culture had lower sensitivity, but highly acceptable detection rates (77.6%) were observed using BCM. APM had very low sensitivity (37.8%) and infection was never detected by plate isolation without positive incubation in BCM. The highest sensitivity (91.8%) for the detection of synovial infection was achieved when the results of incubation in BCM and 16S PCR were combined. For all the tests, the specificity was higher than 90%. 相似文献
4.
Journal of Plant Diseases and Protection - The host response of 17 cover crop cultivars to infection by single-species populations of Pratylenchus hippeastri, Pratylenchus vulnus and Pratylenchus... 相似文献
5.
Sintayehu Legesse Gebre Dirk Cattrysse Esayas Alemayehu Jos Van Orshoven 《国际水土保持研究(英文)》2021,9(4):490-501
Land allocation has been an important issue in land use planning research studies. Land allocation involves different multifunctional activities of maximizing environmental, economic and social benefits. Multi-criteria decision making (MCDM) method is the most popular tool to optimize land allocation problems by considering decision variables, conflicting objectives, and criteria. Hence, decision-makers face problems on how to optimize the land allocation while minimizing the conflicting trade-offs existing in the decision analysis. With this review study, we aim at identifying and extracting information on MCDM methods to solve land allocation problems from English language articles published between 2000 and 2019 and indexed by four scientific literature databases (Web of Science, Science Direct, Scopus, Google scholar). To this end, we applied a systematic literature review approach, i.e. the Preferred Reporting Items for Systematic Reviews and Meta-Analysis procedure (Moher et al., 2009), with a structured database search expression. 120 articles were selected of which, after careful screening of title, keywords and abstract, 69 were retained for detailed review. This review study report compiles comprehensive information by classifying the papers into application area, optimization objectives, criteria used, decision techniques, publication year and study region. In summary, we found that in the last two decades, the use of the MCDM method has increased, particularly in Europe and China. AHP (analytical hierarchal process) is frequently used for multi-attribute land allocation problems with reference to ecotourism and ecosystem management. LP (linear programming) and SA (simulating annealing) methods are predominantly used to optimize multi-objectives complex agricultural and forest land allocation problems respectively. 相似文献
6.
Risk-based surveillance for avian influenza control along poultry market chains in South China: The value of social network analysis 总被引:1,自引:0,他引:1
Martin V Zhou X Marshall E Jia B Fusheng G FrancoDixon MA DeHaan N Pfeiffer DU Soares Magalhães RJ Gilbert M 《Preventive veterinary medicine》2011,102(3):196-205
Over the past two decades, the poultry sector in China went through a phase of tremendous growth as well as rapid intensification and concentration. Highly pathogenic avian influenza virus (HPAIV) subtype H5N1 was first detected in 1996 in Guangdong province, South China and started spreading throughout Asia in early 2004. Since then, control of the disease in China has relied heavily on wide-scale preventive vaccination combined with movement control, quarantine and stamping out. This strategy has been successful in drastically reducing the number of outbreaks during the past 5years. However, HPAIV H5N1 is still circulating and is regularly isolated in traditional live bird markets (LBMs) where viral infection can persist, which represent a public health hazard for people visiting them. The use of social network analysis in combination with epidemiological surveillance in South China has identified areas where the success of current strategies for HPAI control in the poultry production sector may benefit from better knowledge of poultry trading patterns and the LBM network configuration as well as their capacity for maintaining HPAIV H5N1 infection. We produced a set of LBM network maps and estimated the associated risk of HPAIV H5N1 within LBMs and along poultry market chains, providing new insights into how live poultry trade and infection are intertwined. More specifically, our study provides evidence that several biosecurity factors such as daily cage cleaning, daily cage disinfection or manure processing contribute to a reduction in HPAIV H5N1 presence in LBMs. Of significant importance is that the results of our study also show the association between social network indicators and the presence of HPAIV H5N1 in specific network configurations such as the one represented by the counties of origin of the birds traded in LBMs. This new information could be used to develop more targeted and effective control interventions. 相似文献
7.
Jonas Schler Dirk Hinrichs Georg Thaller 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2019,136(6):518-525
During last decades, native uniqueness decreased in local livestock breeds due to the introgression of high‐yielding breeds. Recovery of native uniqueness became important because of conservation aspects regarding native genetic diversity and native traits. Thereby the expectation exists, that the relation between native uniqueness and genetic gain is contradictory. The aim of this study was to explore the influence of native uniqueness on performance traits and the total merit index in a local red cattle breed from Northern Germany. Data contained a pedigree file of 178,255 Red Dual‐Purpose cattle, 809 target genotypes and 3,581 reference genotypes from introgressed breeds. Native genetic contributions were tested for correlation with performance traits of milk yield, longevity, foundation, somatic cells, fertility and maternal calving and the total merit index. The study revealed that native uniqueness is favourably related to longevity (0.16), foundation (0.23), and somatic cells (0.08), and the total merit index (0.10). Selection on native uniqueness could probably lead to an increased longevity, udder health and genetic gain of the Red Dual‐Purpose cattle. Moreover, it was shown that the Red Dual‐Purpose cattle was not upgraded through introgression of high‐yielding breeds. 相似文献
8.
Dirk?Jan?van?der? GaagEmail author Gerrit?Wever 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(1):31-41
Substrates made from rockwool, coir dust, pumice and perlite were compared for conduciveness to Pythium root and crown rot in cucumber under near-commercial conditions. Rockwool slabs of 7 cm height were more conducive to the Pythium disease than coir dust slabs, pumice or perlite under these conditions. Temperature, oxygen concentration and water content were determined in the substrates to explain differences in conduciveness between the inorganic substrates rockwool, pumice and perlite by differences in the physical conditions. Temperature and oxygen concentration could not explain the differences but the higher disease level on rockwool was associated with a much higher water content of this substrate as compared to coir dust, pumice and perlite. Increasing the height of the substrate from 7 to 14 cm greatly decreased the percentage of diseased plants due to the Pythium disease on rockwool but had no effect on the level of disease on perlite when the substrate had been infested 4 cm below the planting hole. This difference in response in substrate height between rockwool and perlite could be explained by a much larger decrease in water content with substrate height in the rockwool than in the perlite substrate. Temperature in the substrates were above 30 °C for more than 6 h on sunny days in June and reached maximum values of 35 °C or more. These temperatures are highly favourable for the pathogen P. aphanidermatum but will have adverse effects on most biocontrol strains. 相似文献
9.
The development of infectiological diagnostic methodology is characterized by saltatoric, revolutionary leaps. Improved sensitivity and specificity, reduction of analytical sample volumes, increased sample throughput, reduced test complexity associated with improved user friendliness are hallmarks of such developments. Apart from purely technical amenities some innovations also enable conceptual adaptations of monitoring strategies. These include the use of diagnostic assays on-site, e. g. in the stable or in the practice. Selecting the assay which is most "fit-for-purpose" among the plethora of sometimes loudly advertised new technology may be difficult even for the well trained and experienced diagnostician. Standardized licensing procedures for infectiological diagnostic kits may be required to guarantee minimal norms of diagnostic quality. At the same time availability of a diversity of diagnostic kits is needed to broaden the base of diagnostic reliability. New infectiological diagnostic innovations will only be useful if the (expanded) results are transposable to the improved practical care of companion animals and farm animal holdings. In addition, the judgment of results, e. g. for epidemiological plausibility, remains a very important issue even when the test results have been produced by novel high technology diagnostics. 相似文献
10.
Andrew Kiggundu Clifford S. Gold Maryke T. Labuschagne Dirk Vuylsteke Schalk Louw 《Euphytica》2003,133(3):267-277
Forty-five Musa clones, including endemic and introduced cultivars plus hybrids, were evaluated for resistance against the banana weevil,
Cosmopolites sordidus, in a field trial in Uganda. The predominant groups of staple crops, East African highland bananas (Musa spp. AAA) and plantains (Musaspp. AAB), as well as plantain-derived hybrids (AAB × AA), showed the highest levels of susceptibility to this pest. These
were followed by dessert bananas (Musa spp. AAA), exotic bananas (Musa spp. ABB) and finally diploids of M. acuminata (AA). Hybrids of banana origin were highly resistant. Some East African highland cultivars, especially brewing types (e.g.,
Kabula, Bagandeseza, Ediirira), showed intermediate levels of resistance. Among the non-highland bananas, high levels of resistance
were observed in Yangambi-Km5 (AAA), Cavendish (AAA), Gros Michel (AAA), Kayinja (ABB, Pisang Awak subgroup), Ndiizi (AB,
Ney Poovan subgroup)and Kisubi (Ney Poovan subgroup). The highest resistance was observed in banana hybrids TMB2×7197-2, TMB2×8075-7
and the wild banana Calcutta-4 (AA). These were considered the best sources of resistance for a weevil resistance-breeding
programme with the two hybrids commonly used as improved male parents.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献