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   133篇
  免费   12篇
林业   22篇
农学   6篇
  28篇
综合类   5篇
农作物   7篇
水产渔业   10篇
畜牧兽医   50篇
园艺   8篇
植物保护   9篇
  2023年   1篇
  2022年   3篇
  2021年   1篇
  2020年   7篇
  2019年   5篇
  2018年   6篇
  2017年   9篇
  2016年   3篇
  2015年   8篇
  2014年   4篇
  2013年   15篇
  2012年   7篇
  2011年   5篇
  2010年   4篇
  2009年   11篇
  2008年   7篇
  2007年   4篇
  2006年   7篇
  2005年   3篇
  2004年   4篇
  2003年   5篇
  2002年   10篇
  2001年   5篇
  2000年   1篇
  1999年   3篇
  1998年   1篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1989年   1篇
  1970年   1篇
排序方式: 共有145条查询结果,搜索用时 93 毫秒
91.
Zinc (Zn) and phosphorus (P) deficiency is a common nutritional problem for the production of many crops in semi-arid Mediterranean region of Turkey. This problem results in the application of increasing amounts of fertilizers. Minerals (such as pyrite) including iron (Fe) and sulfur (S) can decrease soil pH may be a critical factor in crop production under low supply of Zn and P in calcareous and clay soils. The aim of this research was to determine the effect of pyrite application on wheat-maize-wheat growth, P and Zn concentration with three successive pot experiments. Bread (Seri-82) (Triticum durum L.) durum (Kunduru) wheat (Triticum aestivum L.), and maize (Zea mays L.) RX 788 hybrid was grown in Zn and P-deficient calcareous soils from Central Anatolian Sultanönü and Çukurova Karaburun. Plants were grown under greenhouse conditions at five rates of pyrite (0, 0.5, 1, 1.5, and 2 g pyrite kg?1 soil) in three consecutive experiments. Pyrite application increased shoot dry matter production of wheat and maize. With time effect of pyrite on plant growth and nutrient uptake was more. In accordance with growth data, pyrite application enhanced P and Zn concentration of plants, especially under Zn deficient Sultanönü soil then Karaburun soil. Plants grown in Karaburun soil had more P and Zn concentration than grown in Sultanönü soil. The results obtained indicate that pyrite can be used as a zinc fertilizer sources for gramine plants such as wheat and maize.  相似文献   
92.
A hospital‐based case study was conducted at the University of Veterinary Medicine Vienna for a 1‐year period. The purpose of this study was to determine possible alterable and non‐alterable risk factors of equine colic in Austria. The investigated parameters were obtained from hospital medical records (individual factors, duty of the horse, deworming, change in diet and water intake), from questionnaires (feed intake, watering types, housing and pasture practices) and from http://www.orf.at (weather‐related factors). Moreover, 221 collected feed samples were investigated through hygienic quality sensory evaluation and mould, yeast and bacteria presumptive samples were confirmed by microbiological investigation. Variables that were observed from the hospital medical records and found to be significantly associated with colic in a univariate analysis were included in multivariate analysis and the only remaining risk factor was decreased water consumption (p < 0.001, OR = 5.025). Consequently, a total of 2743 horses and 366 cases of colic were observed during the study period. The risk factors for colic in Austria were identified for the first time in this study and these increased risk factors were decreased water consumption, high amount of concentrate intake (p = 0.037), low hygienic quality of hay (p = 0.027) and high temperature on the arrival date (p = 0.003). Results suggest that the occurence of colic may not stop, but may decrease with better feed management practices in Austria.  相似文献   
93.
Uterine tissue from pregnant bitches was investigated by qualitative RT-PCR for the gene expression of local factors potentially important for the implantation of canine embryos. For this purpose, 10 bitches identified as being at the time of implantation or early placentation by means of ultrasonography before ovariohysterectomy (days 20–35, n = 10) provided tissues for comparison to tissue collected in a previous study and identified as early pregnant (n = 10) or non-pregnant (n = 4) by embryo flushing after ovariohysterectomy (days 10–12 after mating; Schäfer-Somi et al. 2008 ). Uterine tissue was excised from the middle of the left horn from early pregnant and non-pregnant animals, including from interplacental and placentation sites. The following genes were investigated: CD-4, -8; cyclooxygenase (COX)-1, -2; granulocyte macrophage-colony stimulating factor (GM-CSF); hepatocyte growth factor (HGF); insulin-like growth factor (IGF)-1, -2; transforming growth factor (TGF) and tumour necrosis factor (TNF)-α; interferon (IFN)-γ; interleukin (IL)-1β, -2, -4, -6, -8, -10, -12; leukaemia inhibitory factor (LIF) and leptin. Gene expression for CD-8, COX-1, TGF-β, HGF, IGF-1, IL-2, -4,-10, IFN-γ and LIF were detected in the pre-implantation uterus, and all except IL-2 and -10 were still detectable during the implantation and placentation stage. During implantation, mRNA for IGF-2 and GM-CSF were additionally detected. The dioestrous uterus differed from the pregnant uterus because of the absence of CD-8, IL-4 and IFN-γ and the expression of CD-4, TNF-α and IL-6. The results suggest that IL-4, IFN-γ, CD-8, GM-CSF and IGF-2 are regulated in a pregnancy-specific manner and that GM-CSF and IGF-2 probably have growth supporting and immune modulating functions during implantation of the canine embryo.  相似文献   
94.
Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV), is one of the most devastating diseases on sugar beet throughout the world. A total of 235 BNYVV-infested soil samples taken from 29 provinces during the growing seasons of 2004–2005 and 2010–2011 were investigated for resistance-breaking properties of BNYVV isolates. BNYVV resistant (Rz1, Rz1?+?R2, Rz1?+?C48?+?minor genes) and susceptible (rz1) sugar beet cultivars were grown in the BNYVV-infested soils by the bait plant technique, and virus infection was evaluated based on disease symptom and DAS-ELISA. Of the soil samples tested, 57.4% produced infection in the roots of sugar beet cultivar (cv.) containing the Rz1 gene, 51.9% in cv. carrying the Rz1?+?Rz2 and 18.9% in cv. carrying the Rz1?+?C48?+?minor genes. Also, the presence of Beet soil-borne virus (BSBV) was evaluated by TAS-ELISA. Additionally, the presence of BNYVV RNA-5 component was investigated by RT–PCR using the primers specific for p26 coding region. Our results revealed that BNYVV isolates compromising resistance genes are highly common and widespread in sugar beet production areas in Turkey, and it seems unlikely that BSBV and/or RNA-5 were directly involved in RB-event.  相似文献   
95.
Occurrence and pathogenicity of Oomycota species causing root rot were investigated in 10 forest tree nurseries in western Turkey. Soil samples (129 in total) taken from the rhizosphere of symptomatic seedlings were baited for Oomycota using young leaves of Quercus suber, Rhododendron simsii and R. ponticum. Oomycota (178 isolates) were obtained by culturing on selective media, and identified using morphological methods followed by PCR and sequencing of the ITS rDNA and cox1 regions. Phytophthora aff. cactorum, P. citricola sensu lato, P. crassamura, P. syringae, Pythium aphanidermatum, Py. intermedium, Py. irregulare, Py. ultimum and Phytopythium vexans were common amongst the isolates. The highest diversity of Oomycota was found in the forest nurseries at Adapazar?‐Hendek and ?zmir‐Torbal?. Pathogenicity tests showed that the isolates caused lesions on a range of host plants. The importance of these nursery infections in transferring potentially damaging oomycete species to Turkish forests is discussed.  相似文献   
96.
Disease incidence and severity was studied for winter wheat variety Bezostaya 1 and susceptible checks based on data from international nurseries from 1969 to 2010 and from 51 countries across major winter wheat production regions totalling 1,047 reports. The frequency of leaf rust and stripe rust occurrence was stable over time with marked increases in severity in 2001–2010 especially in Europe and Central and West Asia. Substantial global reductions in stem rust occurrence were recorded and attributed primarily to use of resistance genes although the recent emergence of race Ug99 makes wheat more vulnerable. The occurrence of powdery mildew remained globally stable over time. It was the most important foliar disease in Western and Southern Europe, where the frequency was very high for all time periods coupled with slight increases in severity during 2001–2010. The durable resistance of variety Bezostaya 1 to all four diseases was demonstrated in the study using comparisons of disease severities of Bezostaya 1 and the most susceptible entries. The Lr34/Yr18/Pm38 pleiotrophic set possessed by Bezostaya 1 is currently an important target for selection because it is now amenable to molecular selection. Increased use of genes like Lr34 combined with strategies to minimize cultivation of extremely susceptible varieties will contribute to long term maintenance of low and non-damaging disease levels. The durable disease resistance of Bezostaya 1, combined with its adaptability and good end-use quality, was a significant reason for its huge impact in agriculture over the last 50?years.  相似文献   
97.
To test how efficiently plantations and seed orchards captured genetic diversity from natural Anatolian black pine (Pinus nigra Arnold subspecies pallasiana Holmboe) seed stands, seed sources were chosen from 3 different categories (seed stands (SS), seed orchards (SO) and plantations (P)) comprising 4 different breeding zones of the species in Turkey. Twenty-five trees (mother trees) were selected from each SS, SO and P seed sources and were screened with 11 Random Amplified Polymorphic DNA (RAPD) markers. Estimated genetic diversity parameters were found to be generally high in all Anatolian black pine seed sources and the majority of genetic diversity is contained within seed sources (94%). No significant difference in genetic diversity parameters (numbers of effective alleles, % of polymorphic loci and heterozygosity) among seed source categories was found, except for a slight increase in observed heterozygosities in seed orchards. For all seed source categories, observed heterozygosity values were higher (Ho = 0.49 for SS, 0.55 for SO and 0.49 for P) than expected ones (He = 0.40 for SS, 0.39 for SO and 0.38 for P) indicating the excess of heterozygotes. In general, genetic diversity in seed stands has been transferred successfully into seed orchards and plantations. However, the use of seeds from seed orchards can increase the amount of genetic diversity in plantations further. The study also demonstrated that number of plus-tree clones (25–38) used in the establishment of seed orchards was adequate to capture the high level of diversity from natural stands.  相似文献   
98.
99.
The aim of this study was to investigate effects of an organophosphate insecticide, diazinon (DI), on pancreas, and possible ameliorating role of vitamins E and C. We examined both in vivo and in vitro effects of DI on serum activities of alkaline phosphatase (ALP), γ-glutamyltransferase (GGT), amylase, and lipase enzymes. We also evaluated possible ameliorating effects of vitamins E and C combination against DI toxicity and blood levels of thiobarbituric acid reactive substances (TBARS) only in vivo. In vivo experimental groups were: control group, DI-treated group, and DI + vitamins E plus C-treated group. In vitro study groups were: control group and DI-treated group. The biochemical analyses were determined in in vitro experiments at both hour 0 and 24 while in in vivo experiments were determined only at hour 24. Lipase activity and TBARS level were found increased by DI in in vivo experiments while lipase activity was found decreased in in vitro experiments. Amylase and ALP activities were found decreased by DI in both in vivo and in vitro experiments. Also, the combination of vitamins E and C was found to partially improve these disorders. These results suggest that DI treatment causes pancreas damage via increasing oxidative stress in rats, and a combination vitamins E and C can reduce this lipoperoxidative effect.  相似文献   
100.
The effects of zinc and vitamin A supplementation to the diet on some blood metabolites were evaluated in Hisex brown laying hens from 56 weeks to 68 weeks of age. A total of 130 birds were divided into two main groups according to vitamin A treatment (0 and 3.44 mg retinyl acetate kg(-1) feed, respectively), each consisting of 65 hens. Hens in both of the main groups were then divided into five zinc treatment groups (0, 25, 50, 100 and 200 mg zinc kg diet(-1) respectively) of 13 hens each. It was observed that plasma T4, T3 and total cholesterol levels were affected by only zinc supplementation. While 100 and 200 mg Zn kg(-1) decreased plasma T4 level compared to control value, plasma T3 level was reduced by 100 mg Zn kg(-1) compared to groups fed less Zn. Adding 50 and 200 mg Zn kg(-1) to the diet increased plasma total cholesterol level in the birds compared to other groups. Vitamin A, zinc, and their interaction did not influence the concentration of plasma high-density lipoprotein (HDL)-cholesterol, glucose and egg yolk cholesterol in laying hens.  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