全文获取类型
收费全文 | 498篇 |
免费 | 47篇 |
专业分类
林业 | 32篇 |
农学 | 28篇 |
基础科学 | 2篇 |
104篇 | |
综合类 | 29篇 |
农作物 | 22篇 |
水产渔业 | 50篇 |
畜牧兽医 | 223篇 |
园艺 | 12篇 |
植物保护 | 43篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 7篇 |
2016年 | 16篇 |
2015年 | 21篇 |
2014年 | 14篇 |
2013年 | 43篇 |
2012年 | 9篇 |
2011年 | 24篇 |
2010年 | 23篇 |
2009年 | 16篇 |
2008年 | 36篇 |
2007年 | 18篇 |
2006年 | 31篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 13篇 |
1999年 | 19篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有545条查询结果,搜索用时 171 毫秒
91.
Gabriela Noronha de Toledo Pamela Rodrigues Reina Moreira Daniele Santos Rolemberg Andréia Coutinho Facin Julio Edward Hough Monteiro Mareliza Possa de Menezes Maria Eduarda Bastos Andrade Moutinho da Conceição Felipe Augusto Ruiz Sueiro Rosemeri de Oliveira Vasconcelos Paola de Castro Moraes Mirela Tinucci Costa Andrigo Barboza de Nardi 《Topics in companion animal medicine》2018,33(2):35-39
Osteosarcoma is the most commonly reported bone tumor in dogs, typically affecting the axial and appendicular skeleton. Involvement of the paranasal sinuses and the nasal cavity is extremely rare. This report describes a 6-year-old, female, cross-breed dog presented with signs of 90 days duration and diagnosed with a mass located in the right nasal cavity. Radiography, rhinoscopy, and computed tomography findings suggested the presence of an intranasal tumor. Osteosarcoma in the nasal cavity was diagnosed based on histopathological examination and clinical and imaging findings. Survival time was 12 months from diagnosis. 相似文献
92.
Assessing human risk of illness with West Nile virus mosquito surveillance data to improve public health preparedness
下载免费PDF全文
![点击此处可从《Zoonoses and public health》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S. Karki N. E. Westcott E. J. Muturi W. M. Brown M. O. Ruiz 《Zoonoses and public health》2018,65(1):177-184
Surveillance for West Nile virus (WNV) and other mosquito‐borne pathogens involves costly and time‐consuming collection and testing of mosquito samples. One difficulty faced by public health personnel is how to interpret mosquito data relative to human risk, thus leading to a failure to fully exploit the information from mosquito testing. The objective of our study was to use the information gained from historic West Nile virus mosquito testing to determine human risk relative to mosquito infection and to assess the usefulness of our mosquito infection forecasting models to give advance warning. We compared weekly mosquito infection rates from 2004 to 2013 to WNV case numbers in Illinois. We then developed a weather‐based forecasting model to estimate the WNV mosquito infection rate one to 3 weeks ahead of mosquito testing both statewide and for nine regions of Illinois. We further evaluated human illness risk relative to both the measured and the model‐estimated infection rates to provide guidelines for public health messages. We determined that across 10 years, over half of human WNV cases occurred following the 29 (of 210) weeks with the highest mosquito infection rates. The values forecasted by the models can identify those time periods, but model results and data availability varied by region with much stronger results obtained from regions with more mosquito data. The differences among the regions may be related to the amount of surveillance or may be due to diverse landscape characteristics across Illinois. We set the stage for better use of all surveillance options available for WNV and described an approach to modelling that can be expanded to other mosquito‐borne illnesses. 相似文献
93.
94.
Mechanisms of glyphosate resistance and response to alternative herbicide‐based management in populations of the three Conyza species introduced in southern Spain
下载免费PDF全文
![点击此处可从《Pest management science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
95.
96.
Yo ra Marrero Yamicela Castillo Oscar Ruiz Eduviges Burrola Claudio Angulo 《农业科学学报》2015,14(3):514-519
In vitro gas production technique (IVGPT) was used with the objective of determining the inclusion effect of live cells of two strains of Candida yeast on in vitro ruminal fermentation of two fibrous substrates. In order to achieve this, two experiments were performed: A) using oat straw (Avena sativa) as substrate; B) using alfalfa hay (Medicabo sativa) as substrate, comparing the effect of two different strains of Candida genre, both isolated from the rumen, on the mentioned substrates. Levica 25 (Candida tropicalis) yeast belongs to the culture collection of the Institute of Animal Science, Cuba, and Levazoot 15 (Candida norvegensis) yeast is part of the collection of the Faculty of Zootechnology and Ecology of the Autonomous University of Chihuahua, Mexico. Both strains demonstrated their potential in activating the ruminal fermentation. They stimulated (P<0.0001) the ruminal fermentation of the substrates under study. However, the Levazoot strain stimulated the dry matter (DM) fermentation of alfalfa in 21.43%, more than Levica 25. It is concluded that there is an influence of yeast strain and diet on the rumen environment and, therefore, it is important to select the appropriate strain in every production condition. 相似文献
97.
98.
Histopathology of infection and colonization of Quercus ilex fine roots by Phytophthora cinnamomi
下载免费PDF全文
![点击此处可从《Plant pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
F. J. Ruiz Gómez R. M. Navarro‐Cerrillo R. Sánchez‐Cuesta A. Pérez‐de‐Luque 《Plant pathology》2015,64(3):605-616
Quercus ilex is one of the European forest species most susceptible to root rot caused by the oomycete Phytophthora cinnamomi. This disease contributes to holm oak decline, a particularly serious problem in the ‘dehesas’ ecosystem of the southwestern Iberian Peninsula. This work describes the host–pathogen interaction of Q. ilex and P. cinnamomi, using new infection indices at the tissue level. Fine roots of 6‐month‐old saplings inoculated with P. cinnamomi were examined by light microscopy and a random pool of images was analysed in order to calculate different indices based on the measured area of pathogen structures. In the early stages of invasion, P. cinnamomi colonizes the apoplast and penetrates cortical cells with somatic structures. On reaching the parenchymatous tissues of the central cylinder, the pathogen develops different reproductive and survival structures inside the cells and then expands through the vascular system of the root. Some host responses were identified, such as cell wall thickening, accumulation of phenolic compounds in the middle lamella of sclerenchyma tissues, and mucilage secretion blocking vascular cells. New insights into the behaviour of P. cinnamomi inside fine roots are described. Host responses fail due to rapid expansion of the pathogen and a change in its behaviour from biotrophic to necrotrophic. 相似文献
99.
ASSESSING CIRCLE OF WILLIS BLOOD CIRCULATION IN DOGS WITH TRANSCRANIAL COLOR-CODED DUPLEX SONOGRAPHY
Francisco J. Duque Jose M. Dominguez-Roldan Patricia Ruiz Concepcion Zaragoza Rafael Barrera-Chacon 《Veterinary radiology & ultrasound》2009,50(5):530-535
Insonation of Circle of Willis by transcranial Doppler duplex color sonography is described in 30 healthy dogs with 15 weighing <33 lb and 15 weighing >33 lb. Imaging was via a temporal window to explore the rostral, middle, and caudal cerebral arteries on both the left and right-hand sides; and through an suboccipital window to study the basilar artery. Normal mean values of the peak systolic velocity (PSV), end diastolic velocity, mean velocity, resistance index (RI), and pulsatility index (PI) were characterized and compared with those obtained in previous studies. There was significant differences in the PSV, RI, and PI in the rostral cerebral artery between dogs weighing <33 vs. >33 lb. Mean PSV was higher in weighing over 33 lb, whereas the mean resistive index and mean PI were lower in these dogs. 相似文献
100.
An integrated sustainability assessment of mediterranean sheep farms with different degrees of intensification 总被引:1,自引:0,他引:1
In the European Mediterranean basin, pasture-based sheep farming systems are mostly located in marginal/High Nature Value areas. These production systems are multifunctional, and their economic, environmental and social roles are equally important and recognised by policy makers and by society. However, the number of animals and holdings is decreasing, and there is great uncertainty regarding the reproducibility of these farming systems, which depends on many internal and external farm factors and their interactions. The aim of this paper was to perform a comprehensive assessment of sustainability in different sheep farming systems in north eastern Spain using the MESMIS framework. We followed a case-study approach to perform an in-depth investigation of 4 sheep meat and dairy farms with different intensities of reproduction management. Critical points of sustainability, including weaknesses and opportunities, were obtained using a participatory process with stakeholders (farmers and technical advisers) that resulted in the selection of 37 sustainability indicators that were classified according to the systemic attributes defined by MESMIS (productivity, stability, self-reliance, adaptability, equity) and according to the classical sustainability pillars (social, economic and environmental). Some underlying patterns could be observed when analysing sustainability pillars, attributes and indicators. A positive relationship between productivity and intensification level in meat farms was observed; however, economic sustainability was determined not only by on-farm but also by off-farm activities. The economic efficiency of farming (without considering subsidies) was mainly explained by the capture of added value in the dairy systems and the combination of high animal productivity as well as high forage and feed self-sufficiency in the meat systems. Social issues were also central to explaining sustainability at the farm level, including the prospects of generational turnover and the manner in which farmers perceive and rate their activity. A clear trade-off between economic and environmental indicators was observed, i.e., the higher the economic sustainability, the lower the environmental sustainability. Each farm scored differently for diverse attributes, pillars and individual indicators. The scores differed according to size, structure, resource availability and managerial skills, which implies that it would be difficult to apply a holistic sustainability analysis to farming systems instead of individual farms. A number of methodological questions arose during the evaluation process relative to the stakeholders perception of these indicators, their relevance and meaning, the reference values for comparison, or their validity to assess sustainability across spatial and temporal scales. These questions are discussed in the paper. 相似文献