全文获取类型
收费全文 | 779篇 |
免费 | 42篇 |
国内免费 | 52篇 |
专业分类
林业 | 90篇 |
农学 | 31篇 |
基础科学 | 32篇 |
97篇 | |
综合类 | 171篇 |
农作物 | 49篇 |
水产渔业 | 63篇 |
畜牧兽医 | 234篇 |
园艺 | 42篇 |
植物保护 | 64篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 16篇 |
2021年 | 13篇 |
2020年 | 15篇 |
2019年 | 13篇 |
2018年 | 39篇 |
2017年 | 28篇 |
2016年 | 32篇 |
2015年 | 15篇 |
2014年 | 30篇 |
2013年 | 53篇 |
2012年 | 39篇 |
2011年 | 85篇 |
2010年 | 32篇 |
2009年 | 41篇 |
2008年 | 44篇 |
2007年 | 27篇 |
2006年 | 25篇 |
2005年 | 39篇 |
2004年 | 28篇 |
2003年 | 43篇 |
2002年 | 77篇 |
2001年 | 50篇 |
2000年 | 27篇 |
1999年 | 15篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1956年 | 1篇 |
1886年 | 1篇 |
排序方式: 共有873条查询结果,搜索用时 15 毫秒
101.
Tolga Guvenc Mustafa Yavuz Gulbahar Murat Yarim Yonca Betil Kabak Onder Karayigit Mahmut Sozmen 《Journal of veterinary science (Suw?n-si, Korea)》2012,13(1):39-42
The aim of this study was to evaluate prognostic and/or diagnostic factors of canine mammary tumors by immunohistochemically analyzing the expression of alpha basic crystallin (αB-c). For this, formalin-fixed, paraffin-embedded blocks of 51 naturally-occurring canine mammary tumors (11 benign and 40 malignant) were used. Tissue from eight normal canine mammary glands were served as a control. Immunohistochemically, in the control mammary tissues, a few luminal epithelial cells were αB-c positive but myoepithelial cells were negative. In benign or simple type malignant tumors, αB-c expression was observed in luminal epithelial cells while the myoepithelial basal cells were negative. In benign or complex type malign tumors, positive staining was predominantly found in the cytoplasm of epithelial cells. Immunoreactivity of αB-c was also observed in neoplastic myoepithelial cells. Statistically, the number of cells immunolabeled with αB-c was found to be significantly different among tissues from normal canine mammary glands, benign lesions, and malignant tumors (p < 0.05). αB-c immunoreactivity was higher in malignant tumors than the control mammary tissues (p < 0.001). Data obtained in the current study revealed a strong association between high expression levels of αB-c and primary mammary gland tumors in canines. 相似文献
102.
We investigated an Armillaria root disease centre in a 60‐year‐old, naturally regenerated Pinus sylvestris stand located at 1250 m altitude in Sinop province in northern Turkey. Based on sequence analysis of the internal transcribed spacer region of the rDNA, the mycelial fans sampled from the infected trees were Armillaria ostoyae. Multilocus genotyping indicated that the fans belonged to a single genet, at least 0.2 ha in size. Drought as a predisposing factor is discussed. The study area received 50–70 and 25–50% of the normal precipitation in May, June and August in 2009 and in August and September in 2010, respectively. Moreover, earlier excavation work to prepare a forest road had probably disrupted the water table in the affected stand. 相似文献
103.
氟苯尼考混悬型微乳剂的急性毒性试验 总被引:2,自引:1,他引:1
为评价氟苯尼考混悬型微乳剂的安全性,按改良寇氏法进行了氟苯尼考混悬型微乳剂的急性毒性试验。根据预实验结果,60只小鼠平均分为6组,雌雄各半,分别按6000、4558.5、3464、2632、2000 mg/kg氟苯尼考混悬型微乳剂和0.5 mL/kg生理盐水注射液给小鼠腹腔一次性注射,同时用氟苯尼考普通注射液做对照,重复上述试验,均连续观察7 d。结果显示:氟苯尼考混悬型微乳剂最大耐受量为6000 mg/kg,其LD50为3658.8 mg/kg,LD5095%可信限为2075.8~5241.8 mg/kg。氟苯尼考注射液的LD50为636.68 mg/kg,LD5095%可信限为538.5~735.1 mg/kg。此剂量氟苯尼考混悬型微乳剂中氟苯尼考的含量相当于临床推荐用量(20 mg/kg)的180倍,表明氟苯尼考混悬型微乳剂毒性显著降低,在治疗剂量范围内使用安全。 相似文献
104.
105.
为了解应用遥感技术估测滴灌小麦氮肥利用效率的可行性,以新春17号、新春6号和新春22号为材料,通过大田试验,分析了不同施氮处理下小麦干物质氮肥偏生产力(RDN)和干物质氮肥农学效率(DMA En)与光谱参数的相关关系,并建立小麦RDN和DMAEn的光谱参数估算模型.结果表明,在分蘖、抽穗和开花期RDN与绿度植被指数和比值植被指数呈极显著正相关,在拔节和抽穗期DMAEn与土壤调整比值植被指数和归一化差值植被指数呈显著正相关.光谱参数估算模型的均方根误差为7.64~33.31,说明利用光谱参数可以有效地估算小麦氮肥利用效率. 相似文献
106.
Serhat Gürel Haluk Başar Ece Keskin Mehmet Sabri Dirim 《Communications in Soil Science and Plant Analysis》2019,50(8):1044-1062
This study was conducted to investigate the various boron fractions in olive tree grown soils. The correlations between boron fractions in leaves, fruits and soil properties were examined. For this purpose cv “Gemlik” olive (Olea europaea L.) orchards were visited. Soil samples from 0–30 cm and 30–60 cm deep, the leaf and fruit samples were collected. The greatest proportion of total soil boron is present in residual form (85–88%). It is followed by organically bound B (2.84–4.50%), specifically adsorbed on soil colloid surfaces (0.93–1.31%), oxides (manganese oxyhydroxides, amorphous Fe and Al oxides, crystalline Fe and Al oxides) bound B (7.27–8.31%). The smallest one readily soluble (extracting plant available) boron values were composed of only 0.40–0.50% of total boron ranging. To determine readily soluble boron five different extraction solutions were in the order Hot water ? 0.01 M CaCl2 ? 1 M NH4OAc ? 0.1 M KCl ? 0.005 M DTPA. Fruit boron concentration and soil boron fractions showed close correlations than leaf boron concentration. 相似文献
107.
Sedat Keleş 《Journal of Sustainable Forestry》2019,38(4):305-326
Forests are among the most important ecosystems that provide various hydrological services including water production and protection because the vast majority of the water available on the earth comes from forested catchments. The forests provide quality and continuous water yield as well as protective services such as flood control, soil protection, landslide protection, avalanche protection, and prevention against rock falls, which are related to water. However, the quality and quantity of all the forest functions are influenced by forest ecosystem structure and composition such as forest type, tree species, age class distribution, biomass, leaf area, basal area, crown closure, and stand development stages. This study provides an assessment of hydrological services of forest ecosystems through the systematic review of relevant literature till 2018. It mainly focuses on water-forest relations and explains how forest ecosystem structure and composition affect water production, quality, and sustainability. Then, a general framework relating to the integration of hydrological services into forest management is concluded in the context of sustainable management of natural resources. 相似文献
108.
109.
110.
The Effect of Kefir as a Dietary Supplement on Nonspecific Immune Response and Disease Resistance in Juvenile Rainbow Trout,Oncorhynchus mykiss (Walbaum 1792) 下载免费PDF全文
Gülşen Uluköy Seçil Metin Ayşegül Kubilay Şefik Güney Pınar Yıldırım Zeynep Güzel‐Seydim Tugba Kok‐Tas Erkan Gümüş 《Journal of the World Aquaculture Society》2017,48(2):248-256
In this study, juvenile rainbow trout fed with commercial pellets containing kefir provided increased nonspecific immune response and improved disease resistance against lactococcosis and yersiniosis. Kefir was used as a feed supplement at 2, 5, and 10% inclusion rates and several nonspecific immune parameters were observed at day(s) 1, 7, 14, 21, 28, and 35 following the treatment. A total of four experimental groups, including control, was established. The various parameters including hematocrits, nitroblue tetrazolium positive neutrophils, total leukocytes, serum lysozyme activity, total serum protein, and immunoglobulin M (IgM) levels were examined. As a result of this study, kefir‐fed fish had an increase in measured nonspecific immune parameters, especially in the group received the 10% kefir treatment. The challenged fish fed with kefir‐supplemented diet showed a better survival rate against Lactococcus garvieae than Yersinia ruckeri. Kefir supplementation reduced fish mortality significantly against L. garvieae. 相似文献