全文获取类型
收费全文 | 458篇 |
免费 | 12篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 15篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 23篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 30篇 |
2012年 | 42篇 |
2011年 | 39篇 |
2010年 | 12篇 |
2009年 | 21篇 |
2008年 | 33篇 |
2007年 | 27篇 |
2006年 | 26篇 |
2005年 | 32篇 |
2004年 | 16篇 |
2003年 | 27篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有470条查询结果,搜索用时 15 毫秒
121.
A Yildirim Y N Sahin H Suleyman A Yilmaz S Yildirim 《Journal of physiology and pharmacology》2007,58(1):105-116
It has been believed that overproduction of free radicals and/or deficiency of antioxidant systems, and stress hormones may play a role in etiopathogenesis of many diseases, including gastric ulcer. This study evaluated whether there was an effect of adrenalectomy on lipid peroxidation [malondialdehyde (MDA)] and antioxidant [superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione (GSH) levels] systems in gastric tissue and erythrocyte in rats. As well, the impacts of administration of prednisolone and epinephrine on these systems in adrenalectomized rats were investigated. Thirty-three rats were randomly grouped as sham-operated (group I), adrenalectomized (group II), adrenalectomized + prednisolone (group III) and adrenalectomized + epinephrine (group IV). After experimental procedures, blood and gastric tissues samples were taken from each animal in all groups. Colorimetric assays were employed to determine gastric tissue and erythrocyte levels of MDA and GSH, and SOD and GPX activities. Adrenalectomy in group II rats caused a marked decrease of SOD and GPX activities and MDA levels, and an increase of GSH levels in gastric tissue and erythrocyte, when compared to sham-operated rats. However, especially epinephrine injection after adrenalectomy resulted in a significantly increase of measured antioxidant enzyme activities and GSH levels in both gastric tissue and erythrocyte. These results indicate that adrenalectomy appeared to alter the levels of antioxidants and lipid peroxidation product in gastric tissue and erythrocyte. Thus, the present study provides a physiological regulatory role of adrenal gland in the maintenance of oxidant/antioxidant balance in gastric tissue and erythrocyte. 相似文献
122.
123.
Using laboratory challenge experiments, we examined whether Campylobacter-specific maternal antibody (MAB) plays a protective role in young chickens, which are usually free of Campylobacter under natural production conditions. Kinetics of C. jejuni colonization were compared by infecting 3-day-old broiler chicks, which were naturally positive for Campylobacter-specific MAB, and 21-day-old broilers, which were negative for Campylobacter-specific MAB. The onset of colonization occurred much sooner in birds challenged at the age of 21 days than it did in the birds inoculated at 3 days of age, which suggested a possible involvement of specific MAB in the delay of colonization. To further examine this possibility, specific-pathogen-free layer chickens were raised under laboratory conditions with or without Campylobacter infection, and their 3-day-old progenies with (MAB(+)) or without (MAB(-)) Campylobacter-specific MAB were orally challenged with C. jejuni. Significant decreases in the percentage of colonized chickens were observed in the MAB(+) group during the first week compared with the MAB(-) group. These results indicate that Campylobacter-specific MAB plays a partial role in protecting young chickens against colonization by C. jejuni. Presence of MAB in young chickens did not seem to affect the development of systemic immune response following infection with C. jejuni. However, active immune responses to Campylobacter occurred earlier and more strongly in birds infected at 21 days of age than those infected at 3 days of age. Clearance of Campylobacter infection was also observed in chickens infected at 21 days of age. Taken together, these findings (i) indicate that anti-Campylobacter MAB contributes to the lack of Campylobacter infection in young broiler chickens in natural environments and (ii) provide further evidence supporting the feasibility of development of immunization-based approaches for control of Campylobacter infection in poultry. 相似文献
124.
The effects of vitamin E (dl-α-tocopheryl acetate) and selenium (Se; Na2-SeO3) on egg production, egg quality, and mineral content of egg yolk in Japanese quails reared under a low ambient temperature
(6°C) were evaluated. Birds (n=300; 7 wk old) were randomly assigned to 12 treatment groups, 25 birds per group. The birds in a 3×2 factorial design received
either three levels of vitamin E (125, 250, and 500 mg/kg diet) or two levels of selenium (0.1 or 0.2 mg/kg diet). After 2
wk on feed, six groups of the birds were maintained at 18°C (thermoneutral temperature [TN]), and the other half were acclimated
over 3 d to a decreased environmental temperature of 6°C (cold stress [CS]). The performance, egg quality, and mineral content
of egg yolk were not influenced by supplemental vitamin E and selenium in quails not exposed to cold stress (p≥0.09). Two hundred fifty and 500 mg vitamin E/kg diet compared with 125 mg/kg diet and higher dietary selenium inclusions
(0.2 vs 0.1 mg/kg) resulted in a better body weight, egg production, and feed efficiency (p=0.01) in quails reared under CS. Similarly, egg weight, egg specific gravity, eggshell thickness, and Haugh unit were positively
influenced with vitamin E (p=0.01) and selenium (p≤0.05) supplementation. Egg yolk concentrations of Zn, Fe, and Mn were higher with higher dietary vitamin E (p=0.01) and selenium (p=0.05). There was no interaction detected for parameters measured in the present study (p≥0.3). The results of the present study showed that a combination of 250 or 500 mg vitamin E and 0.2 mg selenium per kilogram
of diet provides the greatest effects on performance and egg quality of Japanese quails reared under cold stress and suggest
that such a supplementation can be considered as a protective management practice in Japanese quail diets to reduce the detrimental
effects of cold stress. 相似文献
125.
Uysal AC Alagöz MS Unlü RE Sensöz O 《Plastic and reconstructive surgery》2003,112(7):1949-50; author reply 1950-1
126.
A cDNA (LEPS-2) encoding a novel cell wall protein was cloned from shikonin-producing callus tissues of Lithospermum erythrorhizon by differential display between a shikonin-producing culture strain and a non-producing strain. The LEPS-2 cDNA encoded a polypeptide of 184 amino acids. The deduced amino acid sequence exhibited no significant homology with known proteins. Expression of LEPS-2 gene as well as accumulation of LEPS-2 protein was highly correlated with shikonin production in L. erythrorhizon cells in culture. In the intact plant, expression of LEPS-2 was detected only in the roots where shikonin pigments accumulated. Cell fractionation experiments and immunocytochemical analysis showed that the protein was localized in the apoplast fraction of the cell walls. The shikonin pigments were also stored on the cell walls as oil droplets. These results indicate that expression of the LEPS-2 is closely linked with shikonin biosynthesis and the LEPS-2 protein may be involved in the intra-cell wall trapping of shikonin pigments. 相似文献
127.
128.
This experiment was conducted to evaluate the effects of chromium (chromium picolinate, CrPic) and zinc (ZnSO4·H2O) on egg production, egg quality, and serum insulin, corticosterone, glucose, cholesterol, and total protein concentrations
of laying hens reared under a low ambient temperature (6.8°C). One hundred twenty laying hens (Hy-Line; 32 wk old) were divided
into 4 groups, 30 hens per group. The laying hens were fed the control diet (T1) or the control diet supplemented with either
400 μg of Cr/kg of diet (T2), 30 mg of Zn/kg of diet (T3), or 400 μg of Cr plus 30 mg of Zn/kg of diet (T4).
Although the dry matter intake (DMI) was similar (p>0.05) for all treatment groups, supplemental chromium and zinc either individually or together increased live-weight change,
egg production, and improved feed efficiency (p<0.05). However, no significant differences were observed between T4 and T2 or T3. Compared to T1, supplemental chromium and
zinc increased egg weight, eggshell weight, eggshell thickness, egg specific gravity, and Haugh unit (p<0.05) in T2, T3, and T4 groups, among which there was no significant difference. Serum insulin concentration increased (p<0.05) and corticosterone concentration decreased (p<0.05) with dietary chromium and zinc supplementation. Serum glucose and cholesterol concentrations decreased (p<0.05) and protein concentrations increased (p<0.001) with dietary chromium and zinc supplementation in all treatment groups. The results of this study indicated that either
supplemental dietary chromium or zinc increased plasma insulin and decreased corticosterone concentrations and that had a
positive effect on performance of laying hens under low ambient temperature. 相似文献
129.
Nurettin Sahin Maria C. Portillo Yuko Kato & Peter Schumann 《FEMS microbiology letters》2009,296(2):198-202
Three strains of aerobic, Gram-negative, rod-shaped, non-spore-forming, yellow-pigmented bacteria (OD1T , YOxT and NS13), which were isolated in previous studies by enrichment in a mineral medium with potassium oxalate as the sole carbon source, were characterized. On the basis of 16S rRNA gene sequence similarity, strains OD1T , YOxT and NS13 belong to the Betaproteobacteria , most closely related to Oxalicibacterium flavum TA17T (97.2–99.7% sequence similarity). The major whole-cell fatty acids were C16:0 , C16:1 ω7c and C17:0 cyclo. The results of DNA–DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strains OD1T and YOxT from O. flavum TA17T and from each other. Therefore, it is concluded that the strains OD1T and YOxT represent novel species within the genus Oxalicibacterium , for which the names Oxalicibacterium horti sp. nov. (type strain OD1T =DSM 21640T =NBRC 13594T ) and Oxalicibacterium faecigallinarum sp. nov. (type strain YOxT =DSM 21641T =CCM 2767T ) are proposed. 相似文献
130.
Istemihan Tengiz Ertugrul Ercan Fahri Sahin Emin Alioglu Can Duman Guray Saydam Filiz Buyukkececi 《Trials》2005,6(1):1-5