首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   125篇
  免费   5篇
  国内免费   2篇
林业   6篇
农学   9篇
基础科学   1篇
  23篇
综合类   17篇
农作物   7篇
水产渔业   5篇
畜牧兽医   41篇
园艺   2篇
植物保护   21篇
  2023年   1篇
  2022年   6篇
  2021年   4篇
  2020年   4篇
  2019年   4篇
  2018年   8篇
  2017年   6篇
  2016年   2篇
  2015年   1篇
  2014年   7篇
  2013年   12篇
  2012年   9篇
  2011年   8篇
  2010年   2篇
  2009年   4篇
  2008年   7篇
  2007年   2篇
  2006年   4篇
  2005年   4篇
  2004年   2篇
  2003年   5篇
  2002年   1篇
  2001年   3篇
  1999年   1篇
  1996年   2篇
  1995年   1篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1986年   2篇
  1985年   3篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1970年   2篇
  1969年   2篇
  1966年   3篇
  1951年   1篇
排序方式: 共有132条查询结果,搜索用时 15 毫秒
51.
Two different age groups of Holstein Friesian cattle were experimentally infected with Babesiabigemina. Calves of group A (6 months old) did not show noticeable symptoms of babesiosis and had relatively low (0.6%) numbers of parasites in their red blood cells (RBCs). Group B calves (1 year old) had typical signs of the disease; parasites were found in 6.6% of their RBCs. Blood from both groups inoculated into splenectomized calves at 3, 6, 12 and 18 months following initial inoculation demonstrated the presence of B. bigemina, while after 22 months no parasites could be demonstrated.The indirect fluorescent antibody (IFA) test detected babesial antibodies at 4–5 days post inoculation (PI) and reached a maximum titre of 1 : 640 at 2 weeks PI. Following challenge at 2–3 months after initial inoculation, the antibody titre rose sharply to 1 : 2560, then decreased gradually but was still detectable 22 months PI. No correlation was found between antibody titre and the presence of the parasite hin the peripheral blood.  相似文献   
52.
Azaizeh H  Fulder S  Khalil K  Said O 《Fitoterapia》2003,74(1-2):98-108
An ethnobotanical survey was conducted among 31 local Arab practitioners living in Galilee, Negev, Golan Heights and West Bank. Seeing that the Arabic traditional medicine is in danger of disappearing, a multilevel program is required, involving the training of local practitioners, an establishment of a regional medicinal plant botanical garden and a field gene bank for plant preservation.  相似文献   
53.
Lamnai  Kamal  Anaya  Fatima  Fghire  Rachid  Zine  Hamza  Wahbi  Said  Loutfi  Kenza 《Gesunde Pflanzen》2021,73(4):465-478

Irrigation with saline water can act as an alternate water resource and thus plays an important role in saving freshwater resources as well as promoting agriculture. Furthermore, salinity stress is considered one of the major abiotic stress factors, which strongly reduces crop productivity. In this context, the present work was conducted to examine the effect of exogenous salicylic acid (SA) application on salt stress tolerance of strawberry plants. For this purpose, strawberry plants (Fragaria vesca L.), three months old, were treated with three SA concentrations (0?mM, 0.25?mM and 0.5?mM), then subjected to 80?mM NaCl or not. After five weeks of treatment, growth responses, water status, photochemical efficiency and oxidative stress indicators were measured. The obtained results showed that irrigation with saline water negatively affected the growth parameters, the leaf water potential (LWP), the relative water content (RWC), the stomatal conductance (gs) and photochemical efficiency (Fv/Fm). While, the total protein content, the electrolyte leakage (EL), the malondialdehyde (MDA) and the hydrogen peroxide (H2O2) contents were increased in stressed plants compared to unstressed ones. Salt stress also leads to the activation of the antioxidant enzymes. However, the exogenous application of SA under salt stress conditions reduced the H2O2 accumulation, the electrolyte leakage and the MDA content. It has also improved the growth parameters, the LWP, the RWC, the gs, the Fv/Fm, the protein content and the antioxidant enzyme activities (POD, CAT and SOD) in the treated plants compared to those without SA application. Therefore, the beneficial effect of 0.25?mM SA on Fragaria vesca L. salinity tolerance may provide some practical basis for strawberry cultivation under saline conditions.

  相似文献   
54.
菜豆荚斑驳病毒的RT-PCR检测   总被引:1,自引:1,他引:1  
魏梅生  相宁  张春泉 《大豆科学》2005,24(4):317-319
菜豆荚斑驳病毒是对大豆经济具有重要影响的病毒.根据已报道的菜豆荚斑驳病毒外壳蛋白基因序列,设计出一对特异性引物,采用RT-PCR法,可有效地扩增出BPMV不同亚组的4个分离物,得到650 bp大小的PCR产物.这种方法能成功地检测出大豆病叶中的BPMV,结果和酶联检测是一致的,而对大豆种皮中BPMV的检测效果不佳,建议采用酶联的方法进行检测.  相似文献   
55.
The influence of EDTA on lipid oxidation in sugar beet pectin-stabilized oil-in-water emulsions (pH 6, 15% oil, wet basis), prepared from fish oil (FO) and fish oil-extra virgin olive oil (FO-EVOO) (1:1 w/w), as well as the spray-dried microcapsules (50% oil, dry basis) prepared from these emulsions, was investigated. Under accelerated conditions (80 °C, 5 bar oxygen pressure) the oxidative stability was significantly (P < 0.05) higher for FO and FO-EVOO formulated with EDTA, in comparison to corresponding emulsions and spray-dried microcapsules formulated without EDTA. The EDTA effect was greater in emulsions than in spray-dried microcapsules, with the greatest protective effect obtained in FO-EVOO emulsions. EDTA enhanced the oxidative stability of the spray-dried microcapsules during ambient storage (~25 °C, a(w) = 0.5), as demonstrated by their lower concentration of headspace volatile oxidation products, propanal and hexanal. These results show that the addition of EDTA is an effective strategy to maximize the oxidative stability of both FO emulsions and spray-dried microcapsules in which sugar beet pectin is used as the encapsulant material.  相似文献   
56.
‘Orphan’ zoonotic diseases attract disproportionately low scientific and public health attention for the impact that they can have. This article pulls together information on their health burden in the UK from routine and enhanced data sources. These diseases are heterogeneous in nature; some have very low case numbers (e.g. hydatid disease), whilst others affect hundreds of patients each year (e.g. toxoplasmosis). The number of deaths attributed to orphan zoonoses is relatively low, and the majority recorded in this article were caused by toxoplasmosis. There is a clear issue of under‐reporting and under‐diagnosis in the data sets presented, and further work should be carried out to obtain more accurate estimates of the prevalence of zoonotic infections. Joint human and veterinary studies are especially important for these diseases.  相似文献   
57.
The impact of recreational fishing on fish stocks remains largely unknown, as this is inherently difficult to monitor, especially in areas such as the Mediterranean Sea where many species are targeted using a variety of fishing gears and techniques. This study attempts to complement existing data sets and construct the profile of recreational fisheries in the EU‐Mediterranean countries using videos publicly available on social media. A total of 1526 video records were selected, featuring the capture of 7799 fish specimens. The results show recreational fishing is multispecies in nature (26 species contributed to >80% % of the most numerically important species caught) and exhibits a spatially homogeneous pattern, with differences in species composition being mostly dependent on the fishing technique used rather than on the country. Such findings fill an important knowledge gap on recreational fishing activities, and the methodology provides an innovative approach to gather statistics on data‐poor thematic areas that can potentially complement other data sets, such as the EU Data Collection Multi‐Annual Programme.  相似文献   
58.
59.
Information about the variability of different soil attributes within a field is essential for sustainable land management and precision agriculture. Mobile proximal gamma‐ray spectrometry can map soil characteristics of vast areas at different scales rapidly and cost‐effectively. This study aims at investigating reliability and capability of mobile‐gamma‐spectrometry (radiometrics) data to map typical soils of Middle Europe. In this paper, we investigate relationships between the radioelement concentrations (K, U, Th, and dose rate) and soil parameters (texture, CEC, pH, and organic‐C content) at four different field sites and soil textures. The data reliability is confirmed at the survey start. Mobile data have an excellent linear correlation (nearly 1:1) with the stationary readings (of identical devices, acquisition setups, and soil conditions) but moderate correlation with laboratory data (of different devices, setups, and sample conditions). Dried lab samples have systematically higher radioelement concentrations than the field soils (normally wet). Consequently, the mobile‐gamma‐spectrometric data is sufficiently accurate for soil mapping, and its calibration by laboratory data is less useful due to the varying environmental conditions. Single absolute radioelement concentrations show only moderate correlations with the different soil parameters, particularly clay content and CEC. This may be related to varying environmental conditions (soil moisture, soil structure, vegetation, land use, etc.) between the study sites. Investigations of the ratios of radioelement concentrations yield a clear improvement of their correlations to soil parameters, especially for sand and clay contents, CEC, and organic C. Additionally, multiple‐linear‐regression models were established using the element concentrations of potassium and thorium to predict silt content and pH. The results of the highly correlated models were confirmed by comparing with clay and silt content and pH value, respectively, to six additional independent field samples. Briefly, applications of gamma‐ray data for soil mapping offers the possibility of the development of quantitative relationships regarding soil parameters like sand and clay contents, CEC, and organic C. Classification of soil textures by gamma‐ray data seems to be promising, though a broader database of soils is needed for further research. We recommend gamma‐ray mapping as a complementary or even an alternative to common mapping techniques.  相似文献   
60.
This study was conducted in Ethiopia to determine the use of mobile phones in agriculture. The study included 320 household heads who owned mobile phones. Data were collected using an interview schedule. The results revealed that the majority (90.6%) of household heads made phone calls for agricultural purposes. Over three quarters (85.9%) of the household heads received phone calls related to agriculture. Short message service (SMS) was poorly used. It is concluded that mobile phones are playing an important role as an informational medium. Therefore, the Ministry of Agriculture in Ethiopia needs to develop a mobile-based agricultural information dissemination system to enhance information delivery to rural farming households.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号