首页 | 官方网站   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   2331篇
  免费   41篇
  国内免费   41篇
生物科学   2413篇
  2024年   1篇
  2023年   46篇
  2022年   31篇
  2021年   79篇
  2020年   101篇
  2019年   173篇
  2018年   92篇
  2017年   44篇
  2016年   46篇
  2015年   31篇
  2014年   194篇
  2013年   218篇
  2012年   186篇
  2011年   215篇
  2010年   124篇
  2009年   126篇
  2008年   114篇
  2007年   101篇
  2006年   111篇
  2005年   92篇
  2004年   87篇
  2003年   54篇
  2002年   53篇
  2001年   11篇
  2000年   9篇
  1999年   4篇
  1998年   7篇
  1997年   1篇
  1996年   5篇
  1995年   8篇
  1994年   5篇
  1993年   5篇
  1992年   4篇
  1991年   5篇
  1990年   1篇
  1989年   2篇
  1988年   4篇
  1987年   2篇
  1985年   1篇
  1984年   4篇
  1982年   4篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
  1972年   2篇
排序方式: 共有2413条查询结果,搜索用时 15 毫秒
1.
Acute lung injury (ALI) is a serious disease with unacceptably high mortality and morbidity rates. Up to now, no effective therapeutic strategy for ALI has been established. Rutin, quercetin-3-rhamnosyl glucoside, expresses a wide range of biological activities and pharmacological effects, such as anti-inflammatory, antihypertensive, anticarcinogenic, vasoprotective, and cardioprotective activities. Pretreatment with rutin inhibited not only histopathological changes in lung tissues but also infiltration of polymorphonuclear granulocytes into bronchoalveolar lavage fluid in lipopolysaccharide (LPS)-induced ALI. In addition, LPS-induced inflammatory responses, including increased secretion of proinflammatory cytokines and lipid peroxidation, were inhibited by rutin in a concentration-dependent manner. Furthermore, rutin suppressed phosphorylation of NF-κB and MAPK and degradation of IκB, an NF-κB inhibitor. Decreased activities of antioxidative enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and heme oxygenase-1 caused by LPS were reversed by rutin. At the same time, we found that ALI amelioration by chelation of extracellular metal ions with rutin is more efficacious than with deferoxamine. These results indicate that the protective mechanism of rutin is through inhibition of MAPK–NF-κB activation and upregulation of antioxidative enzymes.  相似文献   
2.
3.
The sex pheromone produced by adult females of the potato tuberworm moth was isolated from unmated female moths reared in the laboratory. The gas Chromatographic and mass spectrometric data suggested the pheromone to be a tridecatrienyl acetate. The isolated pheromone was subjected to partial hydrogenation with hydrazine and hydrogen peroxide and subsequent ozonolysis to produce a mixture of ω-acetoxy-alkanals. They were identified by mass Chromatographic technique as 4-acetoxy-butanal, 7-acetoxy-heptanal, and 10-acetoxy-decanal respectively. Consequently, the pheromone was identified as 4,7,10-tridecatrienyl acetate except the geometric configuration.  相似文献   
4.
《Free radical research》2013,47(12):1459-1468
The purpose of the present study was to investigate the protective effect of esculetin (ES) in lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the lung epithelial A549 cells. Mice were intragastrically administered with ES (20 and 40 mg/kg) 1 h prior to LPS challenge. ES pretreatment at doses of 20 and 40 mg/kg effectively attenuated LPS-induced lung histopathological change, myeloperoxidase or MPO activity, inflammatory cells infiltration, pulmonary wet-to-dry weight ratio, and the generation of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in vivo and in vitro. Furthermore, we demonstrated that ES blocked the activation of NF-кB and RhoA/Rho kinase pathways in LPS-induced mice and A549 cells. The results suggested that ES exhibited protective effect on ALI and might attribute partly to the inhibition of NF-кB and RhoA/Rho kinase pathways in vivo and in vitro.  相似文献   
5.
《Developmental cell》2020,52(6):714-730.e5
  1. Download : Download high-res image (188KB)
  2. Download : Download full-size image
  相似文献   
6.
7.
The current examination was intended to observe the defensive impacts of embelin against paraquat‐incited lung damage in relationship with its antioxidant and anti‐inflammatory action. Oxidative stress marker, like malondialdehyde (MDA), antioxidative enzymes, for example, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH Px), inflammatory cytokines, such as interleukin‐1β (IL‐1β), tumor necrosis factor‐α, and IL‐6, histological examination, and nuclear factor kappa B/mitogen‐activated protein kinase (NF‐κB/MAPK) gene expression were evaluated in lung tissue. Embelin treatment significantly decreased MDA and increased SOD, CAT, and GSH Px. Embelin significantly reduced levels of inflammatory cytokines in paraquat‐administered and paraquat‐intoxicated rats. In addition, embelin suggestively decreased relative protein expression of nuclear NF‐κB p65, p‐NF‐κBp65, p38 MAPK, and p‐p38 MAPKs in paraquat‐intoxicated rats. The outcomes show the impact of embelin inhibitory action on NF‐κB and MAPK and inflammatory cytokines release, and the decrease of lung tissue damage caused by paraquat.  相似文献   
8.
Anti-TNF biologics have achieved great success in the treatment of autoimmune diseases and have been the most selling biologics on market. However, the anti-TNF biologics have shown some disadvantages such as poor efficacy to some patients and high risk of infection and malignancies during clinical application. Current anti-TNF biologics are antibodies or antibody fragments that bind to TNF-α and subsequently block both TNF-TNFR1 and TNF-TNFR2 signaling. Transgenic animal studies indicate that TNFR1 signaling is responsible for chronic inflammation and cell apoptosis whereas TNFR2 signaling regulates tissue regeneration and inflammation. Recent studies propose to selectively inhibit TNFR1 to enhance efficacy and avoid side effects. In this review, we introduce the biology of TNF-TNFR1 and TNF-TNFR2 signaling, the advantages of selective inhibition of TNF-TNFR1 signaling and research updates on the development of selective inhibitors for TNF-TNFR1 signaling. Antibodies, small molecules and aptamers that selectively inhibit TNFR1 have showed therapeutic potential and less side effects in preclinical studies. Development of selective inhibitors for TNFR1 is a good strategy to enhance the efficacy and reduce the side effects of anti-TNF inhibitors and will be a trend for next-generation of anti-TNF inhibitors.  相似文献   
9.
Atherogenesis is potentiated by metabolic abnormalities that contribute to a heightened state of systemic inflammation resulting in endothelial dysfunction. However, early functional changes in endothelium that signify an individual''s level of risk are not directly assessed clinically to help guide therapeutic strategy. Moreover, the regulation of inflammation by local hemodynamics contributes to the non-random spatial distribution of atherosclerosis, but the mechanisms are difficult to delineate in vivo. We describe a lab-on-a-chip based approach to quantitatively assay metabolic perturbation of inflammatory events in human endothelial cells (EC) and monocytes under precise flow conditions. Standard methods of soft lithography are used to microfabricate vascular mimetic microfluidic chambers (VMMC), which are bound directly to cultured EC monolayers.1 These devices have the advantage of using small volumes of reagents while providing a platform for directly imaging the inflammatory events at the membrane of EC exposed to a well-defined shear field. We have successfully applied these devices to investigate cytokine-,2 lipid-3, 4 and RAGE-induced5 inflammation in human aortic EC (HAEC). Here we document the use of the VMMC to assay monocytic cell (THP-1) rolling and arrest on HAEC monolayers that are conditioned under differential shear characteristics and activated by the inflammatory cytokine TNF-α. Studies such as these are providing mechanistic insight into atherosusceptibility under metabolic risk factors.  相似文献   
10.
An injection of cortisone acetate at a dose of 5 mg/100 g body weight concomitant with dibutryl cyclic AMP prevents the increase in the activity of rat liver cytosol serine aminotransferase (L-serine: pyruvate aminotransferase, EC 2.6.1.51) elicited by the nucleotide with a lag of about 2 h. If the glucocorticoid is given 2 h prior to the nucleotide inducer, the lag disappears. The inhibitory effect of cortisone acetate gradually decays and is no longer detectable 12 h following its administration. Theophylline, insulin and glucose at doses which affect significantly the level of tyrosine aminotransferase, have no effect on the level of serine aminotransferase and on the cortisone inhibition. The inhibitory effect of the glucocorticoid on the dibutyryl cyclic AMP-mediated increase in serine aminotransferase diminishes with the age of animals. Increase in the enzyme activity by a single dose of glucagon can also be inhibited by cortisone acetate and actinomycin D as in the case with dibutyrl cyclic AMP as an inducer. The possibility of the existence of a specific inhibitory factor which is formed in response to cortisone acetate is discussed.  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-23

京公网安备 11010802026262号