全文获取类型
收费全文 | 1344篇 |
免费 | 110篇 |
国内免费 | 1篇 |
专业分类
林业 | 77篇 |
农学 | 40篇 |
基础科学 | 5篇 |
173篇 | |
综合类 | 221篇 |
农作物 | 74篇 |
水产渔业 | 72篇 |
畜牧兽医 | 696篇 |
园艺 | 20篇 |
植物保护 | 77篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 40篇 |
2020年 | 37篇 |
2019年 | 34篇 |
2018年 | 31篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 28篇 |
2014年 | 31篇 |
2013年 | 50篇 |
2012年 | 64篇 |
2011年 | 83篇 |
2010年 | 51篇 |
2009年 | 39篇 |
2008年 | 67篇 |
2007年 | 56篇 |
2006年 | 52篇 |
2005年 | 47篇 |
2004年 | 38篇 |
2003年 | 33篇 |
2002年 | 45篇 |
2001年 | 19篇 |
2000年 | 29篇 |
1999年 | 17篇 |
1997年 | 13篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 20篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 20篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 14篇 |
1972年 | 15篇 |
1970年 | 7篇 |
1969年 | 8篇 |
1967年 | 7篇 |
排序方式: 共有1455条查询结果,搜索用时 31 毫秒
991.
KM Ketzner AA Stewart CR Byron M Stewart EM Gaughan PD Vanharreveld JD Lillich 《Australian veterinary journal》2009,87(9):363-368
Objective Describe the use of a phalangeal cast as treatment for wounds in the pastern and foot region of horses. Secondly, to evaluate the healing and soundness of horses treated with phalangeal casts.
Design Retrospective study of 49 horses.
Procedures Medical records of 49 horses that were treated with a phalangeal cast for 50 cases of wounds in the pastern and foot region at equine referral hospitals from 1995 to 2006 were reviewed and follow-up information was obtained.
Results Treatment consisted of wound debridement, lavage, wound closure (28 wounds), cast application and antibiotics (84%). At follow-up, the majority of horses were sound (42 of 47 wounds, 89.4%), three horses were still lame and one horse was euthanased because of persistent lameness. Three horses were lost to follow-up. There was no statistical difference between the outcomes of horses treated acutely (<24 h) or after a 24-h delay. Similarly, the involvement of synovial structures in the wound did not significantly influence outcome.
Conclusions In this study, wounds involving the pastern and foot that were treated with a phalangeal cast carried a good prognosis for soundness (89.4%) and cosmetic healing (89.5%). The phalangeal casts were well-tolerated and effective. 相似文献
Design Retrospective study of 49 horses.
Procedures Medical records of 49 horses that were treated with a phalangeal cast for 50 cases of wounds in the pastern and foot region at equine referral hospitals from 1995 to 2006 were reviewed and follow-up information was obtained.
Results Treatment consisted of wound debridement, lavage, wound closure (28 wounds), cast application and antibiotics (84%). At follow-up, the majority of horses were sound (42 of 47 wounds, 89.4%), three horses were still lame and one horse was euthanased because of persistent lameness. Three horses were lost to follow-up. There was no statistical difference between the outcomes of horses treated acutely (<24 h) or after a 24-h delay. Similarly, the involvement of synovial structures in the wound did not significantly influence outcome.
Conclusions In this study, wounds involving the pastern and foot that were treated with a phalangeal cast carried a good prognosis for soundness (89.4%) and cosmetic healing (89.5%). The phalangeal casts were well-tolerated and effective. 相似文献
992.
Authentic samples of commercially produced organic and conventionally grown tomatoes, lettuces, and carrots were collected and analyzed for their delta15N composition in order to assemble datasets to establish if there are any systematic differences in nitrogen isotope composition due to the method of production. The tomato and lettuce datasets suggest that the different types of fertilizer commonly used in organic and conventional systems result in differences in the nitrogen isotope composition of these crops. A mean delta15N value of 8.1 per thousand was found for the organically grown tomatoes compared with a mean value of -0.1 per thousand for those grown conventionally. The organically grown lettuces had a mean value of 7.6 per thousand compared with a mean value of 2.9 per thousand for the conventionally grown lettuces. The mean value for organic carrots was not significantly different from the mean value for those grown conventionally. Overlap between the delta15N values of the organic and conventional datasets (for both tomatoes and lettuces) means that it is necessary to employ a statistical methodology to try and classify a randomly analyzed "off the shelf" sample as organic/conventional, and such an approach is demonstrated. Overall, the study suggests that nitrogen isotope analysis could be used to provide useful "intelligence" to help detect the substitution of certain organic crop types with their conventional counterparts. However, delta15N analysis of a "test sample" will not provide unequivocal evidence as to whether synthetic fertilizers have been used on the crop but could, for example, in a situation when there is suspicion that mislabeling of conventionally grown crops as "organic" is occurring, be used to provide supporting evidence. 相似文献
993.
Sharma S Cao X Gittelsohn J Ho LS Ford E Rosecrans A Harris S Hanley AJ Zinman B 《Public health nutrition》2008,11(8):831-840
OBJECTIVES: To characterise the diet of First Nations in north-western Ontario, highlight foods for a lifestyle intervention and develop a quantitative food-frequency questionnaire (QFFQ). DESIGN: Cross-sectional survey using single 24 h dietary recalls. SETTING: Eight remote and semi-remote First Nations reserves in north-western Ontario. SUBJECTS: 129 First Nations (Oji-Cree and Ojibway) men and women aged between 18 and 80 years. RESULTS: The greatest contributors to energy were breads, pasta dishes and chips (contributing over 20 % to total energy intake). 'Added fats' such as butter and margarine added to breads and vegetables made up the single largest source of total fat intake (8.4 %). The largest contributors to sugar were sugar itself, soda and other sweetened beverages (contributing over 45 % combined). The mean number of servings consumed of fruits, vegetables and dairy products were much lower than recommended. The mean daily meat intake was more than twice that recommended. A 119-item QFFQ was developed including seven bread items, five soups or stews, 24 meat- or fish-based dishes, eight rice or pasta dishes, nine fruits and 14 vegetables. Frequency of consumption was assessed by eight categories ranging from 'Never or less than one time in one month' to 'two or more times a day'. CONCLUSION:We were able to highlight foods for intervention to improve dietary intake based on the major sources of energy, fat and sugar and the low consumption of fruit and vegetable items. The QFFQ is being used to evaluate a diet and lifestyle intervention in First Nations in north-western Ontario. 相似文献
994.
The calystegines detected in tubers from 17 Phureja ( S. tuberosum Group Phureja) lines and five Tuberosum ( S. tuberosum Group Tuberosum) cultivars were identified as the A 3 and B 2 structural types. Their concentration in whole tubers was of a similar order of magnitude in both species, as was the variability in the ratio of B 2 to A 3. On average, calystegine concentrations in the peel were about 13 times that found in the flesh for the five Tuberosum cultivars, and 4 times higher for four Phureja lines. Removal of the peel reduced the calystegine content by an average of over 50% in Tuberosum but by only 30% in Phureja, despite the latter having the greater proportion of peel. The calystegine content of sprouts was also determined for five Tuberosum cultivars and four Phureja lines and was found to include small amounts of four additional types, B 3, B 4, N 1, and X 2, in addition to the more abundant A 3 and B 2. Concentrations in the sprouts of Tuberosum were on average 100 times higher than that in the tuber flesh and 8 times higher than in the peel, whereas for Phureja, the equivalent values were 30 and 7 times higher, respectively. No correlation was found between sprout concentration and either flesh or peel calystegine concentration. 相似文献
995.
Kato A Nasu N Takebayashi K Adachi I Minami Y Sanae F Asano N Watson AA Nash RJ 《Journal of agricultural and food chemistry》2008,56(12):4469-4473
Flavonoids are ubiquitous components in vegetables, fruits, tea, and wine. Therefore, they are often consumed in large quantities in our daily diet. Several flavonoids have been shown to have potential as antidiabetic agents. In the present study, we focused on inhibition of glycogen phosphorylase (GP) by flavonoids. 6-Hydroxyluteolin, hypolaetin, and quercetagetin were identified as good inhibitors of dephosphorylated GP (GPb), with IC 50 values of 11.6, 15.7, and 9.7 microM, respectively. Furthermore, a structure-activity relationship study revealed that the presence of the 3' and 4' OH groups in the B-ring and double bonds between C2 and C3 in flavones and flavonols are important factors for enzyme recognition and binding. Quercetagetin inhibited GPb in a noncompetitive manner, with a K i value of 3.5 microM. Multiple inhibition studies by Dixon plots suggested that quercetagetin binds to the allosteric site. In primary cultured rat hepatocytes, quercetagetin and quercetin suppressed glucagon-stimulated glycogenolysis, with IC 50 values of 66.2 and 68.7 microM, respectively. These results suggested that as a group of novel GP inhibitors, flavonoids have potential to contribute to the protection or improvement of control of diabetes type II. 相似文献
996.
Berry extracts exert different antiproliferative effects against cervical and colon cancer cells grown in vitro 总被引:1,自引:0,他引:1
McDougall GJ Ross HA Ikeji M Stewart D 《Journal of agricultural and food chemistry》2008,56(9):3016-3023
Polyphenol-rich berry extracts were screened for their antiproliferative effectiveness using human cervical cancer (HeLa) cells grown in microtiter plates. Rowan berry, raspberry, lingonberry, cloudberry, arctic bramble, and strawberry extracts were effective but blueberry, sea buckthorn, and pomegranate extracts were considerably less effective. The most effective extracts (strawberry > arctic bramble > cloudberry > lingonberry) gave EC 50 values in the range of 25-40 microg/(mL of phenols). These extracts were also effective against human colon cancer (CaCo-2) cells, which were generally more sensitive at low concentrations but conversely less sensitive at higher concentrations. The strawberry, cloudberry, arctic bramble, and the raspberry extracts share common polyphenol constituents, especially the ellagitannins, which have been shown to be effective antiproliferative agents. However, the components underlying the effectiveness of the lingonberry extracts are not known. The lingonberry extracts were fractionated into anthocyanin-rich and tannin-rich fractions by chromatography on Sephadex LH-20. The anthocyanin-rich fraction was considerably less effective than the original extract, whereas the antiproliferative activity was retained in the tannin-rich fraction. The polyphenolic composition of the lingonberry extract was assessed by liquid chromatography-mass spectrometry and was similar to previous reports. The tannin-rich fraction was almost entirely composed of procyanidins of linkage type A and B. Therefore, the antiproliferative activity of lingonberry was caused predominantly by procyanidins. 相似文献
997.
Christine B. Schmitt Neil D. Burgess Lauren Coad Alexander Belokurov Charles Besanon Lauriane Boisrobert Alison Campbell Lucy Fish Derek Gliddon Kate Humphries Valerie Kapos Colby Loucks Igor Lysenko Lera Miles Craig Mills Susan Minnemeyer Till Pistorius Corinna Ravilious Marc Steininger Georg Winkel 《Biological conservation》2009,142(10):2122-2130
This study presents a global analysis of forest cover and forest protection. An updated Global Forest Map (using MODIS2005) provided a current assessment of forest cover within 20 natural forest types. This map was overlaid onto WWF realms and ecoregions to gain additional biogeographic information on forest distribution. Using the 2008 World Database on Protected Areas, percentage forest cover protection was calculated globally, within forest types, realms and ecoregions, and within selected areas of global conservation importance. At the 10% tree cover threshold, global forest cover was 39 million km2. Of this, 7.7% fell within protected areas under IUCN management categories I–IV. With the inclusion of IUCN categories V and VI, the level of global forest protection increased to 13.5%. Percentage forest protection (IUCN I–IV) varied greatly between realms from 5.5% (Palearctic) to 13.4% (Australasia), and for forest types from 3.2% (temperate freshwater swamp forest) to 28% (temperate broadleaf evergreen forest). Median protection of forest cover in 670 ecoregions (forest above a specified threshold) was 5.9% (IUCN I–IV); at IUCN I–VI, 46% of the ecoregions had less than 10% forest protection. Considering their biodiversity importance, forest protection within global priority areas was insufficient, e.g., median protection of 8.4% in biodiversity hotspots (IUCN I–IV). Results have policy relevance in terms of the target of the Convention on Biological Diversity (CBD), reconfirmed in 2008, to effectively conserve “at least 10% of each of the world’s forest types”. Regular updates of these analyses would allow progress towards achieving that target to be monitored. 相似文献
998.
Hannah Robinson Alison Kelly Glen Fox Jerome Franckowiak Andrew Borrell Lee Hickey 《Euphytica》2018,214(9):151
Root system architecture is fundamental to resource capture and productivity of cereal crops. Understanding the genetics modulating root development will empower plant breeders to design cultivars with optimal root systems for the target environment. Here, we investigate the genetic association between seminal root traits and yield in elite barley (Hordeum vulgare L.) germplasm. A panel of 216 breeding lines from the Northern Region Barley Breeding program in Australia, genotyped with Diversity Arrays Technology markers, were characterised for seminal root angle and number. A high degree of phenotypic variation was evident in the population, ranging from 12.0° to 89.4° and 4.8 to 6.1 for root angle and number, respectively. A quantitative trait locus for root angle (qRA-5) was detected on chromosome 5H and co-located with the previously described RAQ2. The genetic relationship between seminal root traits and yield for the panel was investigated using root phenotypes and yield data from 20 field trials. Genetic correlations with yield ranged from ??0.21 to 0.36 for root angle and from ??0.20 to 0.25 for root number. The direction and magnitude of the correlations for both root traits varied across the environments, but overall root angle was deemed more strongly associated with yield. Here we provide insight into the root phenotypes of breeding lines and deliver a first look at the genetic relationship between root architectural traits and yield in barley breeding trials. 相似文献
999.
An advanced and widely used method of analysis for multi-environment trial data involves a linear mixed model with factor analytic (FA) variance structures for the variety by environment effects. This model can accommodate unbalanced data, that is, not all varieties in all environments, it allows the use of pedigree information and appropriate accommodation of individual trial experimental designs, and most importantly the FA structure for the variety by environment effects is parsimonious and regularly results in a good fit to the data. The model provides accurate predictions of the variety effects for every environment in the data-set but this constitutes a large and unwieldly amount of information to process for the purpose of variety selection. We address this issue in the current paper by proposing factor analytic selection tools to summarise the predictions in a concise yet informative manner. The tools, which are natural derivatives of the FA structure, result in measures of overall performance and stability across the environments in the data-set. All measures are expressed on the same scale as the trait under consideration and can easily be combined to form an index for selection. 相似文献
1000.
qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments
下载免费PDF全文
![点击此处可从《Forest Pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P. Tanguay M. Blais A. Potvin D. Stewart D. Walker N. Nadeau‐Thibodeau P. DesRochers D. Rioux 《Forest Pathology》2018,48(3)
The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR Ct values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease. 相似文献