首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1783篇
  免费   248篇
  国内免费   112篇
  2024年   8篇
  2023年   60篇
  2022年   94篇
  2021年   134篇
  2020年   103篇
  2019年   90篇
  2018年   74篇
  2017年   70篇
  2016年   62篇
  2015年   62篇
  2014年   124篇
  2013年   105篇
  2012年   85篇
  2011年   126篇
  2010年   65篇
  2009年   95篇
  2008年   109篇
  2007年   74篇
  2006年   95篇
  2005年   63篇
  2004年   65篇
  2003年   45篇
  2002年   37篇
  2001年   19篇
  2000年   24篇
  1999年   30篇
  1998年   23篇
  1997年   20篇
  1996年   14篇
  1995年   14篇
  1994年   14篇
  1993年   18篇
  1992年   16篇
  1991年   15篇
  1990年   7篇
  1989年   12篇
  1988年   3篇
  1987年   3篇
  1985年   4篇
  1984年   9篇
  1983年   7篇
  1982年   7篇
  1981年   8篇
  1980年   7篇
  1979年   3篇
  1978年   5篇
  1976年   3篇
  1974年   2篇
  1973年   4篇
  1971年   3篇
排序方式: 共有2143条查询结果,搜索用时 93 毫秒
41.
42.
目的探讨孟鲁司特联合舒利迭对哮喘急性发作期患者疗效及免疫功能的影响。方法 2012年1月至2014年1月选取在本院收治的120例哮喘急性发作期患者为研究对象,根据随机数字表将患者分为观察组及对照组各60例,对照组给予舒利迭雾化吸入治疗,50 mg/250 mg,2次/d,观察组在对照组基础上口服孟鲁司特,10 mg/次,1次/d,疗程为2周。对比分析两组患者治疗效果及治疗前后肺功能及免疫功能的变化。结果观察组总有效率为96.67%,对照组总有效率为76.67%,差异有统计学意义(P0.05)。观察组患者治疗后第1秒呼吸气体的容积(FEV1)、用力呼吸的肺活量(FVC)及FVC占预计值百分比(FVC%)改善优于对照组(P0.05)。观察组治疗后白细胞介素4(IL-4)、免疫球蛋白(Ig E)水平、IL-4/INF-γ显著低于对照组,而干扰素(IFN-γ)与对照组相比差异无统计学意义。结论孟鲁司特联合舒利迭能有效改善哮喘急性发作期患者肺功能及免疫功能,提高哮喘患者治疗效果。  相似文献   
43.
《Zoology (Jena, Germany)》2015,118(6):386-393
The blood trematode Gigantobilharzia huronensis typically infects passerine birds and has not been reported in other orders of wild birds. However, in the summer of 2011 in Tempe, Arizona, USA, mourning doves (Zenaida macroura; order: Columbiformes) were collected with infections of G. huronensis. This is the first report of a natural schistosome infection found in wild populations of doves. We sought to determine if G. huronensis infections alter the general body condition and physiology of doves, a seemingly unlikely host for this parasite. Specifically, we hypothesized that birds infected with schistosomes would exhibit reduced weight as well as increased markers of stress and immune system activation. Adult male mourning doves (n = 14) were captured using walk-in style funnel traps. After weighing the birds, blood and mesenteric tissue samples were collected. We measured biomarkers of stress including circulating heat shock proteins (HSPs) 60 and 70, as well as oxidized lipoproteins in schistosome-infected and non-infected birds. Indices of immune system reactivity were assessed using agglutination and lysis assays in addition to determining the leukocyte to erythrocyte ratios and prevalence of hemoparasite infections from blood smears. Schistosome-infected mourning doves had significantly increased oxidative stress and evidence of HSP70 mobilization. There was no evidence for weight loss in schistosome-infected birds nor evidence of significant immune system activation associated with schistosome infection. This may be a reflection of the small sample size available for the study. These findings suggest that schistosome infections have pathological effects in doves, but the lack of mature worms suggests that infected birds in this sampling may not have been suitable hosts for parasite maturation.  相似文献   
44.
45.
In the past decade, the phenomenon of immune priming was documented in many invertebrates in a large number of studies; however, in most of these studies, behavioral evidence was used to identify the immune priming. The underlying mechanism and the degree of specificity of the priming response remain unclear. We studied the mechanism of immune priming in the larvae of the silkworm, Bombyx mori, and analyzed the specificity of the priming response using two closely related Gram-negative pathogenic bacteria (Photorhabdus luminescens TT01 and P. luminescens H06) and one Gram-positive pathogenic bacterium (Bacillus thuringiensis HD-1). Primed with heat-killed bacteria, the B. mori larvae were more likely to survive subsequent homologous exposure (the identical bacteria used in the priming and in the subsequent challenge) than heterologous (different bacteria used in the priming and subsequent exposure) exposure to live bacteria. This result indicated that the B. mori larvae possessed a strong immune priming response and revealed a degree of specificity to TT01, H06 and HD-1 bacteria. The degree of enhanced immune protection was positively correlated with the level of phagocytic ability of the granular cells and the antibacterial activity of the cell-free hemolymph. Moreover, the granular cells of the immune-primed larvae increased the phagocytosis of a previously encountered bacterial strain compared with other bacteria. Thus, the enhanced immune protection of the B. mori larvae after priming was mediated by the phagocytic ability of the granular cells and the antibacterial activity of the hemolymph; the specificity of the priming response was primarily attributed to the phagocytosis of bacteria by the granular cells.  相似文献   
46.
Inflammation is widely accepted to play a major role in atherosclerosis and other cardiovascular diseases. However, the exact mechanism(s) by which inflammation exerts its pathogenic effect remains poorly understood. A number of oxidatively modified proteins have been associated with cardiovascular disease. Recently, attention has been given to the oxidative compound of malondialdehyde and acetaldehyde, two reactive aldehydes known to covalently bind and adduct macromolecules. These products have been shown to form stable malondialdehyde–acetaldehyde (MAA) adducts that are reactive and induce immune responses. These adducts have been found in inflamed and diseased cardiovascular tissue of patients. Antibodies to these adducted proteins are measurable in the serum of diseased patients. The isotypes involved in the immune response to MAA (i.e., IgM, IgG, and IgA) are predictive of atherosclerotic disease progression and cardiovascular events such as an acute myocardial infarction or coronary artery bypass grafting. Therefore, it is the purpose of this article to review the past and current knowledge of aldehyde-modified proteins and their role in cardiovascular disease.  相似文献   
47.

[Purpose]

The aim of this study was to compare the effectiveness of either resveratrol supplementation or exercise training on macrophage infiltration and switching from M1 to M2 kupffer cells in high fat diet mice.

[Methods]

C57BL/6 mice were separated into 5 groups: normal diet (ND; n = 6), high-fat diet (HD; n = 6), high-fat diet with resveratrol (HR; n = 6), high-fat diet with exercise (HE; n = 6) or high-fat diet with resveratrol and exercise (HRE; n = 6). Resveratrol supplementation mice were orally gavaged with resveratrol (25mg/kg of body weight) dissolved in 50% propylene glycol. Exercise mice ran on a treadmill at 12-20 m/min for 30-60 min/day, 5 times/week for 12 weeks.

[Results]

After 12 weeks of intervention, the liver was analyzed. F4/80 expression was evaluated by western blot while CD11c and CD163 mRNA expressions were evaluated by RT-PCR. The weights of the body and liver were significantly increased in the HD and HR group compared to the ND group (p < 0.01). However, the weights were most effectively reduced in the HE and HRE groups compared to the HD group (p < 0.05). The macrophage marker, F4/80 expression was significantly lower in the HE and HRE groups compared to the HD group (p < 0.05). mRNA expression of the M1 macrophage marker, CD11c, in the HD group was significantly increased compared to the ND group (p < 0.01). mRNA expression of the M2 macrophage specific marker, CD163, in the HE and HRE groups were significantly increased compared to the HD group (p < 0.05). The mRNA expressions of TLR4, ICAM-1 and VCAM-1, which induce pro-inflammatory cytokine production, were strongly decreased in the HR, HE, and HRE groups compared to the HD group.

[Conclusion]

These results suggest that moderate exercise training inhibits macrophage infiltration and up regulation of CD163 expression. However, resveratrol supplementation is not enough to ameliorate obesity-induced macrophage infiltration and switching.  相似文献   
48.
《Cell》2022,185(18):3375-3389.e21
  1. Download : Download high-res image (276KB)
  2. Download : Download full-size image
  相似文献   
49.
A rapid isolation procedure was developed for purification of peroxidase a from Petunia hybrida . Rapid isolation was possible since about 15% of the extracellular protein from stem tissue obtained by vacuum infiltration followed by centrifugation of the tissue represents peroxidase. Purification of peroxidase a from intercellular fluid was achieved by two acetone precipitation steps followed by DEAE-cellulose chromatography.
Three different forms of peroxidase were eluted from DEAE-cellulose at different NaCl concentrations. Isoelectric focusing showed, however, a pI of 3.8 for all three forms of peroxidase a . Only part of the peroxidase a enzymes bound to Concanavalin A indicating heterogeneity in the carbohydrate part. Homology of peroxidase a to the peroxidase G1 group from tobacco is discussed.  相似文献   
50.
The viral infection by SARS-CoV-2 has irrevocably altered the life of the majority of human beings, challenging national health systems worldwide, and pushing researchers to rapidly find adequate preventive and treatment strategies. No therapies have been shown effective with the exception of dexamethasone, a glucocorticoid that was recently proved to be the first life-saving drug in this disease. Remarkably, around 20 % of infected people develop a severe form of COVID-19, giving rise to respiratory and multi-organ failures requiring subintensive and intensive care interventions. This phenomenon is due to an excessive immune response that damages pulmonary alveoli, leading to a cytokine and chemokine storm with systemic effects. Indeed glucocorticoids’ role in regulating this immune response is controversial, and they have been used in clinical practice in a variety of countries, even without a previous clear consensus on their evidence-based benefit.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号