全文获取类型
收费全文 | 387篇 |
免费 | 20篇 |
专业分类
林业 | 25篇 |
农学 | 11篇 |
93篇 | |
综合类 | 50篇 |
农作物 | 25篇 |
水产渔业 | 37篇 |
畜牧兽医 | 128篇 |
园艺 | 13篇 |
植物保护 | 25篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 18篇 |
2020年 | 21篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 11篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 18篇 |
2007年 | 24篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 22篇 |
2003年 | 10篇 |
2002年 | 16篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有407条查询结果,搜索用时 0 毫秒
111.
Chiocchetti R Grandis A Bombardi C Clavenzani P Spadari A Gentile A Bortolami R 《American journal of veterinary research》2005,66(4):710-720
OBJECTIVE: To determine the location, morphology, and neurochemical code of spinal cord and dorsal root ganglion neurons that innervate the gastrocnemius muscle (GM) and superficial digital flexor muscle (FDSM) in cattle. ANIMALS: 5 healthy Friesian male calves. Procedure: 2 different types of neuronalretrograde fluorescent tracers (fast blue and diamidino yellow) were injected into the GM and FDSM, respectively. The neurochemical code (substance P, calcitonin gene-related peptide, galanin, and neuronal nuclear protein) of labeled neurons was investigated by immunohistochemistry. RESULTS: Neurons innervating the GM and FDSM were located along the L6-S2 spinal cord segments and ganglionic levels. A cranial-to-caudal topographic distribution for each muscle was found, indicating that the motor nuclei of the 2 muscles are organized by a somatotopic pattern. The GM and FDSM motoneurons were immunoreactive only for calcitonin gene-related peptide, whereas the afferent neurons were immunoreactive for all of the neurochemical markers considered. CONCLUSION AND CLINICAL RELEVANCE: In our study, location and the extent of neurons that supply the GM and FDSM of cattle were characterized completely. Because the GM and FDSM are involved in spastic paresis of calves and it is thought that spastic paresis results from an excessive activity of the neuromuscular spindle reflex arc, findings in our study may be useful for further electrophysiologic and clinical studies. Knowledge of the neurochemical code of neurons that supply the GM and FDSM in healthy calves could be used to compare chemical alterations in the same neuronal population of affected calves. 相似文献
112.
A case of a feline Merkel cell tumour is described. An 8-year-old, female cat developed a round, alopecic, reddish mass on the nose. Wide excisional surgery was performed with cartilage resection. Histologically the mass was composed of solid islands of mostly basophilic densely packed cells with a scant cytoplasm, which was suggestive of a neuroendocrine origin. Results of immunohistochemical studies using antibodies against neurone-specific enolase, chromogranin, synaptophysin and pan-cytokeratin allowed classification of the lesion as a Merkel cell tumour. Ultrastructurally, dense core granules were identified in the cytoplasm. In a 2-year follow-up no relapses or metastases were observed. The clinical course recorded is in contrast with the malignant nature of a Merkel cell tumour recently described in a cat and of the human Merkel cell tumour, but is similar to the course of the canine Merkel cell tumour which is often benign. Early diagnosis along with the use of wide surgical excision might be considered an important factor in preventing relapse of this tumour. 相似文献
113.
Genchi C Rossi L Cardini G Kramer LH Venco L Casiraghi M Genchi M Agostini A 《Veterinary parasitology》2002,110(1-2):85-91
The authors report the efficacy of an injectable, moxidectin sustained release (SR) formulation for the prevention of canine heartworm infection in endemic areas in northern and central Italy. Three field trials were carried out on a total of 324 dogs. Two hundred forty-three dogs were treated with moxidectin SR 6 months apart and 81 dogs (positive controls) with moxidectin tablets given monthly for 5 consecutive months during the risk season each year throughout the study. Results of testing for microfilariae and circulating adult female antigens were negative for all the experimentally treated dogs at the 6, 7, 11 and 19 months after the last injection. No adverse reactions to moxidectin SR were observed but a moderate pain at palpation and swelling (5-6 cm) at the injection site after the first treatment. In the study areas, prevalence of Dirofilaria immitis infection calculated by testing dogs which had no preventive treatment in the previous transmission season ranged from 33 to 63%. This study confirms the efficacy and safety of injectable, moxidectin SR formulation in the prevention of heartworm infection in dogs and demonstrates that the prophylactic efficacy lasts for the full season and strongly suggests that the product gives 1-year protection. 相似文献
114.
Alessandro?InfantinoEmail author Nicoletta?Pucci 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(4):337-347
The isolation of Pyrenochaeta lycopersici, causal agent of corky root of tomato, is difficult because of its slow growth and poor sporulation. Identification is complicated due the existence of two morphologically similar forms, Types 1 and 2, that differ in several physiological and molecular features. For the rapid and unambiguous identification of isolates, two oligonucleotide primer pairs were designed using ITS region sequences. Specific PCR products of 147 and 209 bp were obtained for isolates of Type 1 and Type 2, respectively. Specificity of both primer pairs was verified using several fungal and bacterial species. As little as 0.7 pg of target DNA could be detected with the protocol. A nested PCR procedure was necessary for the detection of the fungus in plant tissue. This technique will be of use in epidemiological studies and in the implementation of control strategies. 相似文献
115.
Congenital ureteral strictures are rare both in human and veterinary medicine. While the diagnosis is generally made after a symptomatic or febrile urinary tract infection, we report here a case in which this condition represented an incidental finding during routine ultrasonography. To the best of the authors' knowledge imaging findings of a double monolateral ureteral stricture have not previously been reported. 相似文献
116.
Regulating the global fisheries: The World Wildlife Fund, Unilever, and the Marine Stewardship Council 总被引:1,自引:1,他引:0
This analysis uses an analytical frameworkgrounded in political economy perspectives of theglobalization of the agro-food sector combined with acase study approach focusing on the Marine StewardshipCouncil (MSC) to inform discussions regarding thecharacteristics of societal regulation in thepost-Fordist era. More specifically, this analysisuses the case of the emergence of the MSC toinvestigate propositions regarding the existence of,and location of, nascent forms of a transnationalState. The MSC proposes to regulate the certificationof sustainable fisheries at the global level throughan eco-labeling program. The MSC was created in 1996by the transnational environmental organization theWorld Wildlife Fund and the transnational corporationUnilever. The emergence of the MSC has generatedheated discussion in fisheries management circles thatis in general divided along North/South lines. Thisanalysis indicates that the case of the MSC providesvaluable insights into the possible characteristics ofsupranational regulatory mechanisms that might emulatethe role of the nation-State in the post-Fordist era. 相似文献
117.
Alessandro Paletto Isabella De Meo Maria Giulia Cantiani Dario Cocciardi 《Journal of Forest Research》2014,19(5):417-426
Common property rights have a long tradition in the Italian Alps, dating back to the Middle Ages, when alpine village communities managed common forests. On these properties, in accordance with rules aimed at regulating the collective use of resources, shareholders have the right of common use of the land. As many mountainous areas still rely on firewood for the heating of homes, the right to gather firewood from common forests is the most important common property right. In the last few decades, renewable bio-energy production based on forest woody biomass has undergone significant development. In Italy, in communities where the right to gather wood still has economic, social, and cultural relevance, decision makers and community members have a different vision about the use of firewood. This paper focuses on this issue by presenting a case study located in the Italian Eastern Alps, characterised by a historical tradition of common property management. In order to define the optimal strategy to manage the common forests, taking into consideration the local community’s needs, a semi-structured questionnaire was submitted to the administrators of the common forests and to the shareholders. Different scenarios of wood use were developed to support managers and decision makers in identifying on-going trends in firewood demand. The results show that the economic scenario for the development of the bio-energy supply chain cannot be reconciled with the historical tradition and social needs. 相似文献
118.
Tauber E Zordan M Sandrelli F Pegoraro M Osterwalder N Breda C Daga A Selmin A Monger K Benna C Rosato E Kyriacou CP Costa R 《Science (New York, N.Y.)》2007,316(5833):1895-1898
Circadian and other natural clock-like endogenous rhythms may have evolved to anticipate regular temporal changes in the environment. We report that a mutation in the circadian clock gene timeless in Drosophila melanogaster has arisen and spread by natural selection relatively recently in Europe. We found that, when introduced into different genetic backgrounds, natural and artificial alleles of the timeless gene affect the incidence of diapause in response to changes in light and temperature. The natural mutant allele alters an important life history trait that may enhance the fly's adaptation to seasonal conditions. 相似文献
119.
Alessandro Bonanno 《Agriculture and Human Values》1993,10(1):2-10
This article reviews three general themes pertaining to the transformation of Eastern European agriculture from a command system to a market oriented system. The first theme deals with the diverse character of Eastern European agriculture. In a context in which the agricultures of this region are often considered homogenous, acknowledgement of the varied dimension of this sector is a key element in both analytical and political terms. The second theme pertains to the market. The historical and theoretical dispute over the role of the market has not only been central in the socio-economic reorganization of Eastern European countries and agricultures but is also a common element shared with the West. The third and final theme refers to the changing social stratification of rural regions. The emergence of new and powerful social groups and the demise of others represent fundamental aspects in the understanding of possible trajectories for development. The article concludes with a review of the contributions contained in this special issue of Agriculture and Human Values.Alessandro Bonanno is Associate Professor of Rural Sociology at the University of Missouri-Columbia. He is the author of numerous journal articles and books, among themSmall Farms (1987),Sociology of Agriculture (1989),Agrarian Policies and Agricultural Systems (1990), andThe Agricultural and Food Sector in the New Global Era (1993). He is also co-editor of the forthcoming book From Columbus to ConAgra: The Globalization of Agriculture and Food. Since the late 1980s, he has been researching issues pertaining to the Agricultural and Food Sector in selected Eastern European Countries. 相似文献
120.
High-resolution interferometric synthetic aperture radar (InSAR) permanent scatterer data allow us to resolve the rates and variations in the rates of slow-moving landslides. Satellite-to-ground distances (range changes) on landslides increase at rates of 5 to 7 millimeters per year, indicating average downslope sliding velocities from 27 to 38 millimeters per year. Time-series analysis shows that displacement occurs mainly during the high-precipitation season; during the 1997-1998 El Ni?o event, rates of range change increased to as much as 11 millimeters per year. The observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features. Changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides. 相似文献