全文获取类型
收费全文 | 139篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
林业 | 9篇 |
农学 | 8篇 |
28篇 | |
综合类 | 20篇 |
农作物 | 8篇 |
水产渔业 | 29篇 |
畜牧兽医 | 41篇 |
园艺 | 2篇 |
植物保护 | 4篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有149条查询结果,搜索用时 31 毫秒
91.
Simulated maternal pre‐spawning stress affects offspring's attributes in farmed Atlantic salmon Salmo salar (Linnaeus, 1758) 下载免费PDF全文
Marit Skog Eriksen Trygve T Poppe Mark McCormick Børge Damsgård Ragnar Salte Bjarne O Braastad Morten Bakken 《Aquaculture Research》2015,46(6):1480-1489
In fish hormones are released into the nutritive yolk sac during oogenesis in quantities that mirror female plasma levels, thus implying a potential for the maternal endocrine state at spawning to affect offspring characteristics. In the present study, mature female Atlantic salmon, Salmo salar, were given intraperitoneal cortisol implants to investigate potential impacts of simulated stress on offspring ontogeny. Maternal cortisol levels reduced fertilization success and affected several offspring characters: lowered initial survival rates, impaired growth early in life and increased prevalence of morphological abnormalities in adult individuals. In addition, offspring from cortisol administered females displayed increased locomotor activity in an acute confinement test. These results suggest that developmental trajectories of salmon offspring can be considerably altered if their mothers experience severe stress during the final stages of gametogenesis. The present findings may have conceptual and applied ramifications as they demonstrate a mechanism that links the maternal environment to subsequent viability of the progeny. 相似文献
92.
93.
ABSTRACT: BACKGROUND: Starch is the most important source of calories for human nutrition and the majority of it is produced by cereal farming. Starch is also used as a renewable raw material in a range of industrial sectors. It can be chemically modified to introduce new physicochemical properties. In this way starch is adapted to a variety of specific end-uses. Recombinant DNA technologies offers an alternative to starch industrial processing. The plant biosynthetic pathway can be manipulated to design starches with novel structure and improved technological properties. In the future this may reduce or eliminate the economical and environmental costs of industrial modification. Recently, many advances have been achieved to clarify the genetic mechanism that controls starch biosynthesis. Several genes involved in the synthesis and modification of complex carbohydrates in many organisms have been identified and cloned. This knowledge suggests a number of strategies and a series of candidate genes for genetic transformation of crops to generate new types of starch-based polymers. However transformation of cereals is a slow process and there is no easy model system available to test the efficiency of candidate genes in planta. RESULTS: We explored the possibility to use transgenic barley callus generated from immature embryo for a fast test of transgenic modification strategies of starch biosynthesis. We found that this callus contains 4 % (w/w dw) starch granules, which we could modify by generating fully transgenic calli by Agrobacterium-transformation. A Green Fluorescent Protein reporter protein tag was used to identify and propagate only fully transgenic callus explants. Around 1 -- 1.5 g dry weight of fully transgenic callus could be produced in 9 weeks. Callus starch granules were smaller than endosperm starch granules and contained less amylose. Similarly the expression profile of starch biosynthesis genes were slightly different in callus compared with developing endosperm. CONCLUSIONS: In this study we have developed an easy and rapid in planta model system for starch bioengineering in cereals. We suggest that this method can be used as a time-efficient model system for fast screening of candidate genes for the generation of modified starch or new types of carbohydrate polymers. 相似文献
94.
Toby J. Reynolds Ph.D. Student Ruth King John Harwood Morten Frederiksen Michael P. Harris Sarah Wanless 《Journal of Agricultural, Biological & Environmental Statistics》2009,14(4):411-431
Integrated data analyses are becoming increasingly common in studies of wild animal populations where two or more separate
sources of data contain information about common parameters. These types of analyses provide robust parameter estimates which
fully reflect all available information, as well as estimates of parameters that would be unidentifiable in a separate analysis.
In this article we present an integrated Bayesian analysis of four long-term datasets (counts, two mark-recapture-recovery
time series, and productivity) relating to a colony of common guillemots (Uria aalge) on the Isle of May, southeast Scotland. A complication when considering the dynamics of populations of this kind is the
unobservable emigration of immature animals. In the analysis of mark-recapture-recovery data, the rate of emigration is frequently
confounded with that of mark loss and it is only possible to estimate the product of these parameters. By combining all available
data for the Isle of May guillemots in an integrated population model, we are able to estimate these parameters separately
and thus obtain improved estimates of prerecruitment emigration. 相似文献
95.
Anita Jeyam Rachel S. McCrea Thomas Bregnballe Morten Frederiksen Roger Pradel 《Journal of Agricultural, Biological & Environmental Statistics》2018,23(1):1-19
The Cormack–Jolly–Seber (CJS) model assumes that all marked animals have equal recapture probabilities at each sampling occasion, but heterogeneity in capture often occurs and should be taken into account to avoid biases in parameter estimates. Although diagnostic tests are generally used to detect trap-dependence or transience and assess the overall fit of the model, heterogeneity in capture is not routinely tested for. In order to detect and identify this phenomenon in a CJS framework, we propose a test of positive association between previous and future encounters using Goodman–Kruskal’s gamma. This test is based solely on the raw capture histories and makes no assumption on model structure. The development of the test is motivated by a dataset of Sandwich terns (Thalasseus sandvicensis), and we use the test to formally show that they exhibit heterogeneity in capture. We use simulation to assess the performance of the test in the detection of heterogeneity in capture, compared to existing and corrected diagnostic goodness-of-fit tests, Leslie’s test of equal catchability and Carothers’ extension of the Leslie test. The test of positive association is easy to use and produces good results, demonstrating high power to detect heterogeneity in capture. We recommend using this new test prior to model fitting as the outcome will guide the model-building process and help draw more accurate biological conclusions. Supplementary materials accompanying this paper appear online. 相似文献
96.
97.
Azim Saiful Rasmussen Jesper Nielsen Jon Gislum René Laursen Morten Stigaard Christensen Svend 《Precision Agriculture》2019,20(6):1199-1210
Precision Agriculture - The global spatial accuracy of ortho-mosaics based on images from consumer-grade unmanned aerial vehicles (UAVs) is relatively low. The use of ground control points (GCPs)... 相似文献
98.
Boysen L Sørensen P Larsen M Serup J Kristensen F 《American journal of veterinary research》2002,63(4):565-569
OBJECTIVE: To investigate whether the degree of erythema during an induced erythematous reaction, the histamine skin test reaction, can be assessed objectively by use of chromametry and image analysis of digital photographs. ANIMALS: 9 pet dogs (6 Golden Retrievers and 3 yellow Labrador Retrievers). PROCEDURE: Histamine phosphate was injected intradermally, and erythema of the wheal reaction was evaluated during the hour that followed. This was done by use of clinical scores, chromametry, and image analysis of digital photographs. Method reproducibility was tested for visual evaluation of printouts of digital photographs and for image analysis of the same photographs. RESULTS: The coefficient of variation of the technically derived erythema values was < 10%. The reproducibility of image analysis was high and the range of agreement between observers narrow. Using chromametry, it was not possible to differentiate between various degrees of erythema intensity as visually perceived. In contrast, use of image analysis of digital photographs enabled discrimination of slight erythema from moderate and marked erythema. The dynamics of reaction measured by chromametry followed the clinical observation. CONCLUSIONS AND CLINICAL RELEVANCE: Chromametric values are comparable to those obtained by visual inspection. As the result of standardized conditions, chromametry is preferred over digital photography. 相似文献
99.
Simon Chioma Weli Malachy Ifeanyi Okeke Morten Tryland ?ivind Nilssen Terje Traavik 《Canadian journal of veterinary research》2004,68(2):140-145
Avipoxviruses from different geographic regions of the world have been characterized to study their genetic and biological properties, but so far, no such work has been performed on Norwegian isolates. Lesions suggestive of avian pox, found on a Norwegian wild sparrow (Passer domesticus) and wood pigeon (Palumbus palumbus), were obtained in 1972 and 1996, respectively. Histologically, these lesions were demonstrated to be characteristic of poxvirus infections and the poxvirus was observed using an electron microscope. The resulting viruses were propagated in chicken embryo fibroblast cells. Restriction fragment length polymorphism of genomes from 2 Norwegian isolates and fowl pox vaccine strain, generated by BamHI, revealed a high degree of heterogeneity among the isolates. The profiles of avipoxviruses isolated from wild birds were clearly distinct from each other and also to the fowl poxvirus strain. Furthermore, chickens experimentally infected with pigeon poxvirus had higher antibody titers and extensive lesions compared to other isolates. This may suggest that pigeon poxvirus is more virulent than the other isolates. 相似文献
100.
Three pigs were given intravenous injections of disintegrated cells of Salmonella cholerae-suis. One of these pigs developed macroscopic bilateral renal cortical necrosis. Histologic examination revealed, besides total cortical parenchymal necrosis, also severe vascular injury, characterized with fibrinoid necrosis of the vessel walls and fibrin thrombi within their lumina. These findings were interpreted as a result of a generalized Shwartzman reaction, provoked by the action of bacterial endotoxin. 相似文献