全文获取类型
收费全文 | 673篇 |
免费 | 36篇 |
专业分类
林业 | 31篇 |
农学 | 37篇 |
基础科学 | 1篇 |
127篇 | |
综合类 | 25篇 |
农作物 | 128篇 |
水产渔业 | 51篇 |
畜牧兽医 | 266篇 |
园艺 | 9篇 |
植物保护 | 34篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 23篇 |
2017年 | 26篇 |
2016年 | 27篇 |
2015年 | 35篇 |
2014年 | 33篇 |
2013年 | 54篇 |
2012年 | 55篇 |
2011年 | 74篇 |
2010年 | 34篇 |
2009年 | 29篇 |
2008年 | 53篇 |
2007年 | 51篇 |
2006年 | 38篇 |
2005年 | 29篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 21篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1989年 | 2篇 |
排序方式: 共有709条查询结果,搜索用时 46 毫秒
161.
The volatile compositions in dried white ginseng according to species ( Panax ginseng , Panax notoginseng , and Panax quinquefolius ) were analyzed and compared by applying multivariate statistical techniques to gas chromatography-mass spectrometry data sets. Main volatile compounds of ginseng species in the present study were sesquiterpenes, such as bicyclogermacrene, (E)-β-farnesene, β-panasinsene, calarene, α-humulene, β-elemene, etc. In particular, α-selinene, α-terpinolene, β-bisabolene, β-phellandrene, β-sesquiphellandrene, zingiberene, germacrene D, limonene, α-gurjunene, (E)-caryophyllene, δ-cadinene, (E)-β-farnesene, α-humulene, bicyclogermacrene, longiborn-8-ene, β-neoclovene, and (+)-spathulenol were mainly associated with the difference between P. ginseng and P. notoginseng versus P. quinquefolius species. On the other hand, the discrimination between P. ginseng and P. notoginseng could be constructed by hexanal, 2-pyrrolidinone, (E)-2-heptenal, (E)-2-octenal, heptanal, isospathulenol, (E,E)-2,4-decadienal, 3-octen-2-one, benzaldehyde, 2-pentylfuran, and (E)-2-nonenal. 相似文献
162.
Stochasticity dominates assembly processes of soil nematode metacommunities on three Asian mountains
Shuqi ZOU Jonathan ADAMS Zhi YU Nan LI Dorsaf KERFAHI Binu TRIPATHI Changbae LEE Teng YANG Itumeleng MOROENYANE Xing CHEN Jinsoo KIM Hyun Jeong KWAK Matthew Chidozie OGWU Sang-Seob LEE Ke DONG 《土壤圈》2023,33(2):331-342
Nematodes play an important role in ecosystems; however, very little is known about their assembly processes and the factors influencing them. We studied nematode communities in bulk soils from three Asian mountain ecosystems to determine the assembly processes of free-living nematode metacommunities and their driving factors. On each mountain, elevations span a range of climatic conditions with the potential to reveal assembly processes that predominate across multiple biomes. A phylogenetic nu... 相似文献
163.
Zhou K Hao J Griffey C Chung H O'Keefe SF Chen J Hogan S 《Journal of agricultural and food chemistry》2007,55(9):3729-3736
Fusarium head blight (FHB) has emerged as a major threat to wheat crops around the world, and it has been hypothesized that wheat antioxidants may play a role against Fusarium infections. The current study aimed to determine antioxidant properties of FHB-resistant wheat grains as compared to susceptible wheat. The wheat samples were collected from a single growing location (Warsaw, VA) and the same growing season. The results showed that both FHB-resistant and -susceptible wheat grains exerted strong radical scavenging activities against DPPH* radical [0.91-1.53 micromol of Trolox equivalents (TE)/g], peroxyl radical (15.5-24.5 micromol of TE/g), and hydroxyl radical (15.7-35.8 micromol of TE/g). Their total phenolic contents ranged from 888 to 1117 microg of gallic acid equivalents (GAE)/g. Five phenolic acids including ferulic, syringic, vanillic, caffeic, and p-coumaric acids were determined in soluble and insoluble fractions of wheat grains, altogether with a range of 219-389 microg/g. On average, the FHB-resistant wheat group showed significantly higher average values in DPPH* and hydroxyl radicals scavenging activities (30 and 41% higher, respectively) than the FHB-susceptible wheat group. 相似文献
164.
Yoot Mo Lee Min Jae Seong Jae Woong Lee Yong Kyung Lee Tae Myoung Kim Sang-Yoon Nam Dae Joong Kim Young Won Yun Tae Seong Kim Soon Young Han Jin Tae Hong 《Journal of veterinary science (Suw?n-si, Korea)》2007,8(1):27-38
Bisphenol A (BPA), a ubiquitous environmental contaminant, has been shown to cause developmental toxicity and carcinogenic effects. BPA may have physiological activity through estrogen receptor (ER) -α and -β, which are expressed in the central nervous system. We previously found that exposure of BPA to immature mice resulted in behavioral alternation, suggesting that overexposure of BPA could be neurotoxic. In this study, we further investigated the molecular neurotoxic mechanisms of BPA. BPA increased vulnerability (decrease of cell viability and differentiation, and increase of apoptotic cell death) of undifferentiated PC12 cells and cortical neuronal cells isolated from gestation 18 day rat embryos in a concentration-dependent manner (more than 50 µM). The ER antagonists, ICI 182,780, and tamoxifen, did not block these effects. The cell vulnerability against BPA was not significantly different in the PC12 cells overexpressing ER-α and ER-β compared with PC12 cells expressing vector alone. In addition, there was no difference observed between BPA and 17-β estradiol, a well-known agonist of ER receptor in the induction of neurotoxic responses. Further study of the mechanism showed that BPA significantly activated extracellular signal-regulated kinase (ERK) but inhibited anti-apoptotic nuclear factor kappa B (NF-κB) activation. In addition, ERK-specific inhibitor, PD 98,059, reversed BPA-induced cell death and restored NF-κB activity. This study demonstrated that exposure to BPA can cause neuronal cell death which may eventually be related with behavioral alternation in vivo. However, this neurotoxic effect may not be directly mediated through an ER receptor, as an ERK/NF-κB pathway may be more closely involved in BPA-induced neuronal toxicity. 相似文献
165.
Min Young Lee Sang Hun Lee Seung Gon Lee Soo Hyun Park Chai Yong Lee Kye Hun Kim Sun Ho Hwang Sang Yub Lim Young Keun Ahn Ho Jae Han 《Journal of veterinary science (Suw?n-si, Korea)》2007,8(1):7-14
The production of miniature animals has been suggested for use in organ transplantation. At present, many of the studies about application of animal organs to human have been focused on pigs because of the number of advantages involved and due to their similarities with human. However, a physiological analysis of the organs to be transplanted has not yet been carried out. Therefore, this study analyzed whether or not there were physiological and morphological differences in the hearts of conventionally-reared pigs and micropigs. In this study, the morphological and physiological functions of the heart were examined using radiographic and echocardiographic equipment. In the lateral radiographic view, the heart of the micropig has a larger cardiac long axis : short axis ratio than does the conventional pig, but the difference in the vertebral heart score was not significant. In addition, there were no morphological differences on the X-ray fluoroscopic view. There were no differences in echocardiographic values, except for several values in the left ventricle traces. Overall, it is expected that the values measured in this study will contribute to understanding of the physiological characteristics of micropigs. 相似文献
166.
Park ES Jo S Yi SJ Kim JS Ee HS Lee IS Seo KM Sung JK Lee I Yoon YS 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(2):107-114
Capsaicin, one of the pungent principles of hot pepper, has been reported to cause a cessation of increases in body weight and fat gain induced by high-fat feeding. Especially, in body weight and feeding control, cholecystokinin (CCK) has been well known as a satiety signal and neuropeptide Y (NPY) has been described as one of the most potent orexigenic signals. This study was carried out to investigate the effect of capsaicin on CCK- and NPY- immunoreactivities (IR) in the brain of high-fat fed rats. The animals were divided into normal-fat diet (NF), high-fat diet (HF) and high-fat diet containing capsaicin (HF-CAP) groups. Mean body weight gain (MBWG) of HF group was higher than that of NF group. However, in HF-CAP group, MBWG was lower than that of HF group. CCK-IR in suprachiasmatic nucleus (SCN), paraventricular nucleus (PVN), median eminence (ME), arcuate nucleus (ARC) and amygdala was not prominent in all the groups. In cerebral cortex, CCK-IR was more reduced in HF-CAP group than in the other groups. In the HF-CAP group, NPY-IR in the hypothalamic nuclei, amygdala and cerebral cortex was more poorly found than in the NF and HF groups. It is concluded that (1) NPY-IR may react more sensitively on capsaicin than CCK-IR, (2) no rapid increase of body weight in capsaicin treated rats may result from the diminished food intake through the low expression of NPY in hypothalamus in HF-CAP group. 相似文献
167.
Immunohistochemical localization of endothelial and inducible nitric oxide synthase within neurons of cattle with rabies 总被引:1,自引:0,他引:1
Shin T Weinstock D Castro MD Hamir AN Wampler T Walter M Kim HY Acland H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(5):539-541
The expression of constitutive endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) in the brains of cattle with natural rabies was studied. Increased expression of eNOS was detected in neurons of the brain stem and Purkinje cells of cerebellum. By contrast, iNOS was diffusely localized in the cytoplasm of affected neurons, and some inflammatory cells were positive. eNOS and rabies antigen were co-localized in inclusion bodies (Negri bodies) in neurons. The specific localization of eNOS, but not iNOS, in the Negri bodies suggests that eNOS is involved in the formation of rabies virus inclusion bodies. 相似文献
168.
Moo Sung Lee Min Gyu Ha Hyun Jin Ko Kap Seung Yang Wan Jin Lee Min Park 《Fibers and Polymers》2000,1(1):32-36
An alternative strategy to reduce the percolation threshold of carbon black (CB) in polymer blends was investigated using
random copolymer ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and a styrene-methyl methacrylate random
copolymer (SMMA). The target morphology was to selectively locate CB particles in the encapsulating layer of SMMA during melt
mixing. The CB used in this study is BP-2000 from Cabot and has a strong selective affinity to PS. Even when the CB was premixed
with SMMA, it moves to the PS phase during the melt mixing. However, we also observed the CB particles located at the interface
between SMMA and PS phases. Through this study it is found that the interaction between polymers and CB particles is critical
for selectively localizing CB particles in multi-component polymer blends. Although appropriate processing condition may retard
the movement of CB particles to the polymer phase with affinity, it cannot prevent it completely and locate them to the SMMA
phase, which is not thermodynamically favored. To locate CB particles in an encapsulating layer of ternary polymer blends,
first of all, polymers forming it should have selective affinity to CB. 相似文献
169.
The present study was undertaken to compare the effect of salinomycin and Bacillus subtilis on growth performance, serum antibody levels against Clostridium spp. and Eimeria spp., and cytokine mRNA expression levels in broiler chickens raised in the used litter. Broiler chickens fed a diet containing salinomycin showed lower (P < 0.05) body weights compared with the control diet-fed counterparts. Serum nitric oxide levels were significantly (P < 0.05) elevated in chickens fed the B. subtilis-enriched diet compared with those on either the salinomycin-fed or control diet-fed chickens. None of the dietary treatments affected (P > 0.05) serum antibody levels against Clostridium perfringens toxins. Both salinomycin and B. subtilis significantly lowered (P < 0.05) the serum levels of Eimeria-specific antibodies compared with the control group. Salinomycin, but not B. subtilis, significantly modulated (P < 0.05) the expression of cytokines encoding interferon-γ (IFN-γ), interleukin10 (IL-10) and tumor necrosis factor superfamily 15 (TNFSF15) compared with the control group. In conclusion, dietary salinomycin and B. subtilis affected serum anticoccidial antibody and intestinal cytokine expression, but failed to improve growth performance in broiler chickens. Further study is warranted to investigate the mode of action of salinomycin on host immune response and growth performance in broiler chickens. 相似文献
170.
Jae Hoon Shin Je Kyung Seong Sun Shin Yi 《Journal of veterinary science (Suw?n-si, Korea)》2014,15(1):19-26
Type 1 diabetes is a common metabolic disorder accompanied by increased blood glucose levels along with glucocorticoid and cognitive deficits. The disease is also thought to be associated with environmental changes in brain and constantly induces oxidative stress in patients. Therefore, glucocorticoid-mediated negative feedback mechanisms involving the glucocorticoid receptor (GR) binding site are very important to understand the development of this disease. Many researchers have used streptozotocin (STZ)-treated diabetic animals to study changes in GR expression in the brain. However, few scientists have evaluated the hyperglycemic period following STZ exposure. In the present study, we found GR expression in the hippocampus varied based on the period after STZ administration for up to 4 weeks. We performed immunohistochemistry and Western blotting to validate the sequential alterations of GR expression in the hippocampus of STZ-treated type 1 diabetic rats. GR protein expression increased significantly until week 3 but decreased at week 4 following STZ administration. GR expression after 70 mg/kg STZ administration was highest at 3 weeks post-treatment and decreased thereafter. Although STZ-induced increase in GR expression in diabetic animals has been described, our data indicate that researchers should consider the sequential GR expression changes during the hyperglycemic period following STZ exposure. 相似文献