全文获取类型
收费全文 | 1131篇 |
免费 | 100篇 |
国内免费 | 81篇 |
专业分类
林业 | 113篇 |
农学 | 127篇 |
基础科学 | 50篇 |
172篇 | |
综合类 | 370篇 |
农作物 | 72篇 |
水产渔业 | 115篇 |
畜牧兽医 | 182篇 |
园艺 | 74篇 |
植物保护 | 37篇 |
出版年
2024年 | 6篇 |
2023年 | 18篇 |
2022年 | 45篇 |
2021年 | 56篇 |
2020年 | 47篇 |
2019年 | 51篇 |
2018年 | 41篇 |
2017年 | 49篇 |
2016年 | 47篇 |
2015年 | 56篇 |
2014年 | 58篇 |
2013年 | 75篇 |
2012年 | 61篇 |
2011年 | 85篇 |
2010年 | 90篇 |
2009年 | 65篇 |
2008年 | 70篇 |
2007年 | 55篇 |
2006年 | 54篇 |
2005年 | 37篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 28篇 |
1999年 | 17篇 |
1998年 | 19篇 |
1997年 | 17篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1973年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1312条查询结果,搜索用时 213 毫秒
111.
融资困难是制约我国国有企业实施管理层收购(MBO)的主要障碍之一。如何缓解融资困境是管理层必须面对的问题。本文根据我国目前金融制度及融资环境的特点,提出具有中国特色的“三步”MBO融资法,该方法可以有效缓解我国国有企业MBO的融资困境。 相似文献
112.
Rebel JM van Dam JT Zekarias B Balk FR Post J Flores Miñambres A ter Huurne AA 《British poultry science》2004,45(2):201-209
1. A study was conducted to investigate the effects of several vitamins and trace elements chickens and in chickens experimentally infected with malabsorption syndrome (MAS). 2. Vitamins and trace minerals in feed were varied. Breeders received either a basal amount of vitamins and trace minerals (low mix) or an increased amount (high mix). Their progeny also received either a low mix or a high mix. Effects of different breeder and broiler mix combinations on broiler performance, heamatology, spleen weight and humoral response were examined in control chickens. The effects of the different feeds and breeder, broiler combinations at the severity and recovery of MAS infection were also studied. 3. In general, the immune system can be stimulated by addition of vitamins and trace minerals, without affecting the growth potential of the controls. The number of leukocytes increased on d 1 in the broilers descended from breeders receiving high mix. The response to Newcastle disease virus boost was affected by the different amount of vitamins. 4. When breeders received a high mix the number of infiltrating polymorphonuclear leukocytes in the intestine was higher compared with breeders receiving basal amounts of minerals and vitamins. Also the recovery rate of intestinal lesions, cystic crypts of Lieberkühn and villus atrophy, as observed by histopathology, was faster in the groups where the breeders received high mix. 相似文献
113.
114.
Kim YH Kim ES Ko BS Oh SE Ryuk JA Chae SW Lee HW Choi GY Seo DW Lee MY 《Journal of animal science》2012,90(7):2075-2083
This study describes a method for discriminating Rangifer antlers from true Cervus antlers using agarose gel electrophoresis, capillary electrophoresis, quantitative real-time PCR, and allelic discrimination. Specific primers labeled with fluorescent tags were designed to amplify fragments from the mitochondrial D-loop genes for various Cervus subspecies and Rangifer tarandus differentially. A 466-bp fragment that was observed for both Cervus and Rangifer antlers served as a positive control, while a 270-bp fragment was specifically amplified only from Rangifer antlers. Allelic discrimination was used to differentiate between Cervus and Rangifer antlers, based on the amplification of specific alleles for both types of antlers. These PCR-based assays can be used for forensic and quantitative analyses of Cervus and Rangifer antlers in a single step, without having to obtain any sequence information. In addition, multiple PCR-based assays are more accurate and reproducible than a single assay for species-specific analysis and are especially useful in this study for the identification of original Cervus deer products from fraudulent Rangifer antlers. 相似文献
115.
Reducing methane emissions and the methanogen population in the rumen of Tibetan sheep by dietary supplementation with coconut oil 总被引:1,自引:0,他引:1
Ding X Long R Zhang Q Huang X Guo X Mi J 《Tropical animal health and production》2012,44(7):1541-1545
The objective was to evaluate the effect of dietary coconut oil on methane (CH(4)) emissions and the microbial community in Tibetan sheep. Twelve animals were assigned to receive either a control diet (oaten hay) or a mixture diet containing concentrate (maize meal), in which coconut oil was supplemented at 12?g/day or not for a period of 4?weeks. CH(4) emissions were measured by using the 'tunnel' technique, and microbial communities were examined using quantitative real-time PCR. Daily CH(4) production for the control and forage-to-concentrate ratio of 6:4 was 17.8 and 15.3?g, respectively. Coconut oil was particularly effective at reducing CH(4) emissions from Tibetan sheep. The inclusion of coconut oil for the control decreased CH(4) production (in grams per day) by 61.2%. In addition, there was a positive correlation between the number of methanogens and the daily CH(4) production (R?=?0.95, P?0.001). Oaten hay diet containing maize meal (6:4) plus coconut oil supplemented at 12?g/day decreases the number of methanogens by 77% and a decreases in the ruminal fungal population (85-95%) and Fibrobacter succinogenes (50-98%) but an increase in Ruminococcus flavefaciens (25-70%). The results from our experiment suggest that adding coconut oil to the diet can reduce CH(4) emissions in Tibetan sheep and that these reductions persist for at least the 4-week feeding period. 相似文献
116.
117.
Mi Young Kang Jung Eun Moon Sang Chul Lee 《Journal of Crop Science and Biotechnology》2013,16(2):167-171
The effects of the functional rice cultivars giant embryo and Aranghyangchal on the body weight and lipid metabolism in male C57BL/6N mice under high fat diet conditions were investigated. The animals were randomly placed into four dietary groups: normal control (NC group), high fat (HF group), and high fat supplemented with giant embryo (HF-GE group) or Aranghyangchal (HF-AR group). After 8weeks, a marked increase in the body weight and plasma triglyceride and total cholesterol concentrations were found in the HF mice relative to the control group. However, the addition of the functional rice samples in the high fat diet reduced the body weight gain and significantly decreased the lipid levels through inhibition of lipogenesis and regulation of adipokine production. The results demonstrate that the functional rice grains giant embryo and Aranghyangchal may both be useful as biomaterials in the development of functional food with therapeutic potential against high fat diet-induced hyperlipidemia. 相似文献
118.
The purpose of this study was to investigate the effects of bending properties and drapability on the hand and appearance of wool-blended fabrics for comparison of real clothing with online and 3D virtual garments. Objective evaluations were performed by measuring mechanical properties of fabrics, while subjective evaluations were performed by subjects evaluating sensory images of fabrics; real clothing evaluations were performed offline and online, and 3D virtual garments were evaluated. Bending properties and drape coefficients of fabrics were affected by wool blending ratio, and fabrics with high wool blending ratio showed low stiffness, warm-cool, weight, and high smoothness, drapability image. In the real clothing evaluation, stiffness image showed many differences with online evaluation with respect to wool blending ratio. Objective bending properties and drape coefficients showed no correlation with subjective sensory images offline. For the online results, objective mechanical properties had good correlations with all sensory images except smoothness. Stiffness and warm-cool online scores were higher than the offline ones and the offline drapability was higher than the online one for 100 % wool fabrics. Thus, clothing was generally evaluated online as more hard and moist than real clothing. For the virtual garment evaluation, sensory images had no difference according to wool blending ratio compared with real clothing. Many differences in subjective sensory images between real clothing and virtual garments were observed, except for smoothness and weight images. The results showed that it is difficult to exactly predict the hand and appearance of clothing according to fabric properties using 3D virtual garment system. 相似文献
119.
Hao Jia Wei Chen Xiaoping Yu Xiuhua Wu Shuai Li Hong Liu Jiru Liao Weihua Liu Mantian Mi Longjian Liu Daomei Cheng 《Journal of veterinary science (Suw?n-si, Korea)》2013,14(3):345-353
The effects of black rice anthocyanidins (BRACs) on retinal damage induced by photochemical stress are not well known. In the present study, Sprague-Dawley rats were fed AIN-93M for 1 week, after which 80 rats were randomly divided into two groups and treated with (n = 40) or without BRACs (n = 40) for 15 days, respectively. After treatment, both groups were exposed to fluorescent light (3,000 ± 200 lux; 25℃), and the protective effect of dietary BRACs were evaluated afterwards. Our results showed that dietary BRACs effectively prevented retinal photochemical damage and inhibited the retinal cells apoptosis induced by fluorescent light (p < 0.05). Moreover, dietary BRACs inhibited expression of AP-1 (c-fos/c-jun subunits), up-regulated NF-κB (p65) expression and phosphorylation of IκB-α, and decreased Caspase-1 expression (p < 0.05). These results suggest that BRACs improve retinal damage produced by photochemical stress in rats via AP-1/NF-κB/Caspase-1 apoptotic mechanisms. 相似文献
120.
S. Miño J. Matthijnssens A. Badaracco L. Garaicoechea M. Zeller E. Heylen M. Van Ranst M. Barrandeguy V. Parreño 《Veterinary microbiology》2013,161(3-4):239-246
Equine group A rotavirus (RVA) strains are the most important cause of gastroenteritis in equine neonates and foals worldwide, and G3P[12] and G14P[12] are epidemiologically the most important genotypes. The genotype constellation of an unusual Argentinean G3P[3] RVA strain (RVA/Horse-wt/E3198/2008/G3P[3]) detected in fecal samples of a diarrheic foal in 2008 was shown to be G3–P[3]–I3–R3–C3–M3–A9–N3–T3–E3–H6. Each of these genotypes has been found typically in feline and canine RVA strains, and the genotype constellation is reminiscent to those of Cat97-like RVA strains. However, the phylogenetic analyses revealed only a distant relationship between E3198 and known feline, canine and feline/canine-like human RVA strains. Surprisingly, a rather close relationship was found between E3198 and simian RVA strains RVA/Simian-tc/USA/RRV/1975/G3P[3] for at least 5 gene segments. RRV is believed to be a reassortant between a bovine-like RVA strain and a RVA strains distantly related to feline/canine RVA strains. These analyses indicate that E3198 is unlikely to be of equine origin, and most likely represents a RVA interspecies transmitted virus, possibly in combination with one or more reassortments, from a feline, canine or related host species to a horse. Further studies are in progress to evaluate if this strain was a single interspecies transmission event, or if this strain started to circulate in the equine population. 相似文献