全文获取类型
收费全文 | 92篇 |
免费 | 8篇 |
国内免费 | 23篇 |
专业分类
林业 | 7篇 |
农学 | 11篇 |
基础科学 | 9篇 |
27篇 | |
综合类 | 42篇 |
农作物 | 2篇 |
水产渔业 | 3篇 |
畜牧兽医 | 17篇 |
园艺 | 2篇 |
植物保护 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 3篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有123条查询结果,搜索用时 78 毫秒
101.
The salmon louse, Lepeophtheirus salmonis, is an ectoparasitic copepod that infests both wild and farmed salmonid fish. Salmon lice are a major disease problem in the farming of Atlantic salmon, Salmo salar L., and the possibility of salmon lice playing a role in the decline of wild anadromous stocks has also been raised. Lepeophtheirus salmonis can detect a range of stimuli (pressure/moving water, chemicals and light) in the external environment. However, the response thresholds to various stimuli, and the spatial and temporal scales over which they operate in the context of host location, are largely unknown. In this context, we attempted to determine whether salmon lice copepodids settle onto hosts more effectively, or at different locations on the fish's body, under different qualities of light. Lice settlement trials were conducted under three lighting conditions; L1: unpolarized under ultraviolet A (UVA)-through visible; L2: unpolarized without UVA (control); L3: 100% linearly polarized without UVA. A dark control was also conducted. No statistically significant difference in lice settlement was found. While changes in light intensity are involved in host detection at spatial scales on the order of metres, the results presented here suggest that it is not the primary sensory modality underlying host location at smaller spatial scales (cm to mm). 相似文献
102.
The pattern of porcine alveolar macrophage (AM) activation upon classical stimuli of two strains of African swine fever (ASF) viruses, an attenuated ASFV-BA71V and virulent ASFV-Georgia2007 were investigated. In an in vitro experiment ASFV-Georgia2007-infected AM showed M1 polarization pattern different from the one induced by classical stimuli. Altered morphology, appearance of binuclear cells, decreased synthesis of IFN-alpha as well as IFN-epsilon was observed compared with attenuated ASFV-BA71V, and decreased synthesis of IFN-omega compared with intact cells. However, CD68 level did not significantly differ between alveolar macrophage populations infected by ASFV-Georgia2007 and control group, while both LPS/IFN-gamma stimulation and non-pathogenic ASFV-BA71V virus increased the level of CD68 soluble receptor.AM infection with ASFV-Georgia2007 resulted in remarkable DNA proliferation whereas LPS/IFN-gamma and ASFV-BA71V induced less expressed DNA proliferation in activated cells. The higher value of nitric oxide was obvious in the cells infected with ASFV-BA71V, compared to ASFV-Georgia2007 and LPS/IFN-gamma activated cells.In conclusion, pattern of activation of alveolar macrophages induced by ASFV-Georgia2007 virus differs from the one expressed in LPS/IFN-gamma- and ASFV-BA71V-activated cells. ASFV-BA71V and LPS/IFN-gamma share similar antiviral response of porcine AM. Therefore we assume that wild type virulent ASFV can partially down regulate antiviral response of AM and conclude that evolutionary decrease of virulence in ASFV is related to alterations of control of the host cell antiviral response. 相似文献
103.
Baikui Wang Yanping Wu Rongrong Liu Han Xu Xiaoqiang Mei Qinqin Shang Shijie Liu Dongyou Yu Weifen Li 《Animal Science Journal》2020,91(1)
Lactobacillus rhamnosus GG (LGG) is increasingly applied in functional food products and acts as a probiotic model in nutritious and clinical studies. Increasing evidences have revealed the immune modulation of LGG on macrophages. The aim of this study is to investigate the effect of LGG on macrophage polarization of murine bone marrow‐derived macrophages (BMDMs). BMDMs were treated with 108 colony‐forming units (CFU)/ml LGG for 1.5, 3, and 6 hr. Results showed that LGG obviously upregulated the mRNA expression of M1‐associated cytokines (p < .05), including interleukin‐1 beta (IL‐1β), IL‐6, tumor necrosis factor‐alpha (TNF‐α), and inducible nitric oxide synthase (iNOS), whereas had no effect on the expression of M2‐associated markers (p > .05), including arginase 1 (Arg1), mannose receptor, and chitinase‐like protein 3 (YM1). Furthermore, LGG markedly increased the expression of pro‐inflammatory cytokines (IL‐12p40, cyclooxygenase‐2 [COX‐2], and interferon‐γ [IFN‐γ]) (p < .05) and anti‐inflammatory cytokines (IL‐10, IL‐4, and transforming growth factor‐β [TGF‐β]) (p < .05). In addition, we also found that TLR2/MyD88/MAPK signaling pathway was required for LGG‐induced M1 macrophage polarization and M1‐related cytokines expression. Together, these findings demonstrate that probiotic LGG facilitates M1 polarization of BMDMs, suggesting that LGG may have an immunotherapeutic potential in regulating the host defense against pathogen invasion. 相似文献
104.
膜技术广泛的应用于水处理过程中,而膜污染和浓差极化限制了它的推广应用。计算流体动力学的应用在减轻膜污染与浓差极化方面起到了非常显著的作用,本文论述了计算流体动力学技术在膜处理中强化传质、降低能耗方面的应用、膜组件几何形状的优化、描述膜处理过程中所应用的数学模型的发展以及有待进一步解决的主要问题。 相似文献
105.
106.
脉冲磁场对枯草芽孢杆菌细胞膜流动性的影响 总被引:1,自引:0,他引:1
研究了脉冲磁场对枯草芽孢杆菌细胞膜流动性的影响。以DPH为探针,在 35℃标记45min后采用荧光偏振法测定了枯草芽孢杆菌细胞膜的荧光偏振度和荧光各异向性的变化。结果表明,荧光偏振度和荧光各异向性随着磁场强度和脉冲数的增加而增加,2.0T、2.5T处理25~30个脉冲,3.0T处理 20~30个脉冲,3.3T处理10~30个脉冲时细胞膜的荧光偏振度与对照组相比差异显著(P<0.05), 2.0T处理30个脉冲和2.5T处理25~30个脉冲,3.0T处理20~30个脉冲,3.3T处理15~30个脉冲,荧光各异向性与对照组相比差异显著(P<0.05)。由此表明,脉冲磁场可使枯草芽孢杆菌细胞膜流动性下降,而细胞膜流动性的下降会引起细胞膜功能的丧失,这可能是导致细胞死亡的原因。 相似文献
107.
108.
邵耀椿 《扬州大学学报(农业与生命科学版)》1989,(3)
利用2mW He-Ne激光测量了植物种子的透射率、散射和偏振度。结果表明激光对一些植物种皮的透射率为20-32%,对半颗种子的透射率为3.2-12%;偏振激光通过种皮后,偏振度0;高期诉激光束通过种皮后,受散射影响。光强偏离高斯分布,光束扩展,光斑变大,并出现一个峰值。说明激光光子能进入胚中与生物大分子直接发生作用。并根据透射光强分布的实验结果,解释了激光育种中存在的现象:激光束即使有点偏离胚,仍能引起生物效应,而激光束对准胚照射效果更明显。 相似文献
109.
Stournara A Minas A Bourtzi-Chatzopoulou E Stack J Koptopoulos G Petridou E Sarris K 《Veterinary microbiology》2007,119(1):53-64
The serological response of young and adult sheep vaccinated conjunctivally with Rev-1 vaccine was assessed by fluorescence polarization assay (FPA), Rose Bengal test (RBT), complement fixation test (CFT), modified Rose Bengal test (m-RBT), indirect ELISA (i-ELISA) and competitive ELISA (c-ELISA), at different post vaccination intervals. One hundred and thirty six adult sheep and 64 lambs were used in the study. The vaccinated animals were bled prior to vaccination (0 day) and thereafter at 21st, 42nd, 35th, 63rd, 91st, 125th, 159th, and 223rd and 330th day post vaccination. The majority of animals (young and adult) showed positive reaction by FPA, RBT, CFT, m-RBT and c-ELISA 21 days post vaccination, whereas by i-ELISA at 42 days. All tests perform equal when animals vaccinated as young are tested 125 days (4 months) post vaccination. In case of animals vaccinated at adulthood, FPA, RBT, CFT and c-ELISA perform equal if the animals are tested 223 days (approximately 8 months) post vaccination. I-ELISA and m-RBT show low specificity if ewes vaccinated at adulthood are tested 330 days (11 months) post vaccination. If control of brucellosis in sheep is based on conjunctivally vaccination of lambs with Rev-1, the vaccinated animals can be tested by any test used for diagnosis of B.melitensis infection accurately at least 4 months post vaccination. If brucellosis control is based on mass vaccination the use of m-RBT and i-ELISA is not recommended for testing adult animals at least for 330 days (11 months) post vaccination due to tests low specificity. Further research is needed so the appropriate cut-offs to be established for FPA, c-ELISA or i-ELISA to become valuable tools for the eradication of Brucella spp. infection in small ruminants in areas where vaccination is practiced. 相似文献
110.
将发育不同时期的兔胚和移核胚的卵裂球细胞核与去核的成熟卵母细胞共同组成移核胚,通过中间受体培养和移植实验检验胚胎的发育能力。结果表明,(1)兔囊胚之前各个时期的胚胎细胞核均可使移核胚发育到囊胚;(2)胚胎极化前后的卵裂球参与组成的移核胚发育到囊胚的比例无显著差异。但极化后 64细胞胚的卵裂球与去核卵母细胞的融合率低于极化前的 8细胞胚胎卵裂球;(3)兔 16细胞胚与去核的卵母细胞组成的移核胚可以发育到期,产仔率为 3.16% ;(4)兔移核胚卵裂球用于连续核移植,其后 2 代均可发育成囊胚,其中第 1 代移核胚与第 2 代移核胚发育率相似,但显著高于第 3 代移核胚;(5)兔移核胚和各代连续移核胚卵裂球与去核卵的融合率无显著差异。 相似文献