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   191篇
  免费   15篇
  2022年   2篇
  2021年   6篇
  2019年   7篇
  2018年   2篇
  2017年   3篇
  2016年   5篇
  2015年   10篇
  2014年   11篇
  2013年   5篇
  2012年   14篇
  2011年   22篇
  2010年   16篇
  2009年   8篇
  2008年   15篇
  2007年   16篇
  2006年   14篇
  2005年   13篇
  2004年   10篇
  2003年   9篇
  2002年   3篇
  2001年   2篇
  1992年   1篇
  1990年   1篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
排序方式: 共有206条查询结果,搜索用时 46 毫秒
41.
Weanling female Wistar rats were supplemented with fish oil (1 g/kg body weight) for one generation. The male offspring received the same supplementation until to adult age. Rats supplemented with coconut fat were used as reference. Some rats were inoculated subcutaneously with a suspension (2 x 10(7) cells/mL) of Walker 256 tumor. At day 3, when the tumor was palpable, rats were treated with naproxen (N) (0.1 mg/mL), clenbuterol (Cb) (0.15 mg/kg body weight), and insulin (I) (10 U/kg body weight). At day 14 after tumor inoculation, the animals were killed. Tumor was removed and weighed. Blood, liver, and skeletal muscles were also collected for measurements of metabolites and insulin. In both tumor-bearing untreated rats and tumor-bearing rats supplemented with coconut fat, tumor growth, triacylglycerol, and blood lactate levels were higher, and glycogen content of the liver, blood glucose, cholesterol and HDL-cholesterol levels were lower as compared with the non-tumor-bearing and fish oil supplemented groups. Fish oil supplementation of tumor-bearing rats led to a partial recovery of the glycogen content in the liver and a full reversion of blood glucose, lactate, cholesterol, and HDL-cholesterol levels. The treatment with N plus Cb plus I attenuated cancer cachexia and decreased tumor growth in both coconut fat and fish oil supplemented rats. In conclusion, chronic fish oil supplementation decreased tumor growth and partially recovered cachexia. This beneficial effect of fish oil supplementation was potentiated by treatment with naproxen plus clenbuterol plus insulin.  相似文献   
42.
The existence of estrogen receptors (ERs) in oligodendrocytes (OLGs) in vivo and in vitro is unresolved, as their presence has been reported in some studies and their absence in others. Using molecular and immunocytochemical techniques, we describe the subcellular localization of ERalpha and ERbeta in OLGs in vivo and in vitro. Both ERalpha and ERbeta are detected in an immortalized OLG cell line and in enriched OLG cultures by RT-PCR and western blot. Immunocytochemistry of OLGs from enriched cultures shows ERalpha receptors are nuclear, whereas ERbeta receptors are cytoplasmic. Confocal and deconvolution microscopy of enriched OLG cultures reveals ERbeta immunoreactivity is concentrated in perikarya and veins of OLG membrane sheets; lesser reactivity is present in their plasma membranes and nuclei. In vivo, we readily detect ERalpha in neurons but not in OLGs, even though we used different fixation procedures and different ERalpha antibodies. The presence of ERalpha in cultured OLGs may be due to culture media that contains factors stimulating ERalpha expression but are reduced in normal brain. In vivo, ERbeta immunoreactivity is readily detectable in OLG cytoplasm and in myelin sheaths. Incubation of glial cultures without or with increasing concentrations of 17beta-estradiol (E2) shows that E2 significantly accelerates OLG process formation.  相似文献   
43.
Transthyretin (TTR) is a tetrameric β-sheet-rich transporter protein directly involved in human amyloid diseases. Several classes of small molecules can bind to TTR delaying its amyloid fibril formation, thus being promising drug candidates to treat TTR amyloidoses. In the present study, we characterized the interactions of the synthetic triiodo L-thyronine analogs and thyroid hormone nuclear receptor TRβ-selective agonists GC-1 and GC-24 with the wild type and V30M variant of human transthyretin (TTR). To achieve this aim, we conducted in vitro TTR acid-mediated aggregation and isothermal titration calorimetry experiments and determined the TTR:GC-1 and TTR:GC-24 crystal structures. Our data indicate that both GC-1 and GC-24 bind to TTR in a non-cooperative manner and are good inhibitors of TTR aggregation, with dissociation constants for both hormone binding sites (HBS) in the low micromolar range. Analysis of the crystal structures of TTRwt:GC-1(24) complexes and their comparison with the TTRwt X-ray structure bound to its natural ligand thyroxine (T4) suggests, at the molecular level, the basis for the cooperative process displayed by T4 and the non-cooperative process provoked by both GC-1 and GC-24 during binding to TTR.  相似文献   
44.

Background

Changes in kidney function, as assessed by early and even small variations in serum creatinine (ΔsCr), affect survival in adults following cardiac surgery but such associations have not been reported in infants. This raises the question of the adequate assessment of kidney function by early ΔsCr in infants undergoing cardiac surgery.

Methodology

The ability of ΔsCr within 2 days of surgery to assess the severity of kidney injury, accounted for by the risk of 30-day mortality, was explored retrospectively in 1019 consecutive neonates and infants. Patients aged ≤ 10 days were analyzed separately because of the physiological improvement in glomerular filtration early after birth. The Kml algorithm, an implementation of k-means for longitudinal data, was used to describe creatinine kinetics, and the receiver operating characteristic and the reclassification methodology to assess discrimination and the predictive ability of the risk of death.

Results

Three clusters of ΔsCr were identified: in 50% of all patients creatinine decreased, in 41.4% it increased slightly, and in 8.6% it rose abruptly. Mortality rates were not significantly different between the first and second clusters, 1.6% [0.0–4.1] vs 5.9% [1.9–10.9], respectively, in patients aged ≤ 10 days, and 1.6% [0.5–3.0] vs 3.8% [1.9–6.0] in older ones. Mortality rates were significantly higher when creatinine rose abruptly, 30.3% [15.1–46.2] in patients aged ≤ 10 days, and 15.1% [5.9–25.5] in older ones. However, only 41.3% of all patients who died had an abrupt increase in creatinine. ΔsCr improved prediction in survivors, but not in patients who died, and did not improve discrimination over a clinical mortality model.

Conclusions

The present results suggest that a postoperative decrease in creatinine represents the normal course in neonates and infants with cardiac surgery, and that early creatinine variations lack sensitivity for the assessment of the severity of kidney injury.  相似文献   
45.
Abstract manganese lipoxygenase (Mn-LO) oxygenates 18:3n-3 and 18:2n-6 to bis-allylic 11S-hydroperoxy fatty acids, which are converted to 13R-hydroperoxy fatty acids. Other unsaturated C(16)-C(22) fatty acids, except 17:3n-3, are poor substrates, possibly because of ineffective enzyme activation (Mn(II)-->Mn(III)) by the produced hydroperoxides. Our aim was to determine whether unsaturated C(16)-C(22) fatty acids were oxidized by Mn(III)-LO. Mn(III)-LO oxidized C(16), C(19), C(20), and C(22) n-3 and n-6 fatty acids. The carbon chain length influenced the position of hydrogen abstraction (n-8, n-5) and oxygen insertion at the terminal or the penultimate 1Z,4Z-pentadienes. Dilinoleoyl-glycerophosphatidylcholine was oxidized by Mn-LO, in agreement with a "tail-first" model. 16:3n-3 was oxidized at the bis-allylic n-5 carbon and at positions n-3, n-7, and n-6. Long fatty acids, 19:3n-3, 20:3n-3, 20:4n-6, 22:5n-3, and 22:5n-6, were oxidized mainly at the n-6 and the bis-allylic n-8 positions (in ratios of approximately 3:2). The bis-allylic hydroperoxides accumulated with one exception, 13-hydroperoxyeicosatetraenoic acid (13-HPETE). Mn(III)-LO oxidized 20:4n-6 to 15R-HPETE ( approximately 60%) and 13-HPETE ( approximately 37%) and converted 13-HPETE to 15R-HPETE. Mn(III)-LO G316A oxygenated mainly 16:3n-3 at positions n-7 and n-6, 19:3n-3 at n-10, n-8, and n-6, and 20:3n-3 at n-10 and n-8. We conclude that Mn-LO likely binds fatty acids tail-first and oxygenates many C(16), C(18), C(20), and C(22) fatty acids to significant amounts of bis-allylic hydroperoxides.  相似文献   
46.
We sought to examine whether cyclic tensile strain (CTS) regulates the gene expression of tumor necrosis factor (TNF)-alpha, its receptors TNFR1 and TNFR2, and inducible nitric oxide synthase (iNOS) under inflammatory conditions, and whether these effects of CTS are sustained. Rat temporomandibular joint disc cells (TDC) were exposed to CTS in the presence or absence of interleukin (IL)-1beta for 4 and 24h. Cells were also stimulated with IL-1beta for 24h while being subjected to CTS only for the initial 1, 2, 4, 8, and 12h or the entire 24h incubation time. Furthermore, cells were incubated with IL-1beta for 24, 36, or 48 h while being exposed to CTS only for the initial 8h. Gene expression of TNF-alpha, its receptors, and iNOS was analyzed by RT-PCR, whereas protein synthesis was determined by ELISA for TNF-alpha, immunofluorescence for TNFRs, and Griess reaction for nitric oxide. CTS inhibited the IL-1beta-stimulated synthesis of TNF-alpha, TNFR2, and iNOS. TNFR1 was constitutively expressed but not regulated by IL-1beta or CTS. Application of CTS for only 1 or 2h during a 24h incubation with IL-1beta was sufficient to inhibit IL-1beta-induced upregulation of TNF-alpha, TNFR2, and iNOS. However, for maximal inhibition of these genes a longer exposure of CTS was required. These findings are the first to show that biomechanical signals regulate the expression of TNFR2 but not TNFR1 under inflammatory conditions. Furthermore, the antiinflammatory effects of biomechanical signals on TDC are maintained for prolonged periods of time but are transient.  相似文献   
47.
48.
Transient receptor potential ankyrin 1 (TRPA1), a membrane protein ion channel, is known to mediate itch and pain in skin. The function of TRPA1, however, in psoriasiform dermatitis (PsD) is uncertain. Herein, we found that expression of TRPA1 is highly up‐regulated in human psoriatic lesional skin. To study the role of TRPA1 in PsD, we assessed Psoriasis Severity Index (PSI) scores, transepidermal water loss (TEWL), skin thickness and pathology, and examined dermal inflammatory infiltrates, Th17‐related genes and itch‐related genes in c57BL/6 as wild‐type (WT) and TRPA1 gene knockout (KO) mice following daily application of topical IMQ cream for 5 days. Compared with WT mice, clinical scores, skin thickness change and TEWL scores were similar on day 3, but were significantly decreased on day 5 in IMQ‐treated TRPA1 KO mice (vs WT mice), suggesting reduced inflammation and skin barrier defects. Additionally, the relative area of epidermal Munro's microabscesses and mRNA levels of neutrophil inducible chemokines (S100A8, S100A9 and CXCL1) were decreased in the treated skin of TRPA1 KO mice, suggesting that neutrophil recruitment was impaired in the KO mice. Furthermore, mast cells, CD31+ blood vascular cells, CD45+ leukocytes and CD3+ T cells were all reduced in the treated skin of TRPA1 KO mice. Lastly, mRNA expression levels of IL‐1β, IL‐6, IL‐23, IL‐17A, IL‐17F and IL‐22 were decreased in TRPA1 KO mice. In summary, these results suggest a key role for TRPA1 in psoriasiform inflammation and raising its potential as a target for therapeutic intervention.  相似文献   
49.
Idiopathic nephrotic syndrome (INS) is caused by renal diseases that increase the permeability of the glomerular filtration barrier without evidence of a specific systemic cause. The aim of the present work was to reveal inherent molecular features of INS in children using combined urinary proteomics and metabolomics profiling. In this study, label-free mass spectrometric analysis of urinary proteins and small molecule metabolites was carried out in 12 patients with INS versus 12 sex- and age-matched control subjects with normal renal function. Integration and biological interpretation of obtained results were carried out by Ingenuity IPA software. Validation of obtained proteomics data was carried out by Western blot method. Proteomics data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD000765. This study indicates for the first time that paediatric INS is associated with up-regulation of afamin, hydroxyphenylacetate and uridine, and concomitant down-regulation in glutamine and phenylalanine levels, and many of these molecular species were previously shown to be involved in oxidative stress. Further studies in larger patient population are underway to investigate the role of oxidative stress in renal injury in paediatric INS.  相似文献   
50.
Methionine restriction (MR) decreases body weight and adiposity and improves glucose homeostasis in rodents. Similar to caloric restriction, MR extends lifespan, but is accompanied by increased food intake and energy expenditure. Most studies have examined MR in young animals; therefore, the aim of this study was to investigate the ability of MR to reverse age‐induced obesity and insulin resistance in adult animals. Male C57BL/6J mice aged 2 and 12 months old were fed MR (0.172% methionine) or control diet (0.86% methionine) for 8 weeks or 48 h. Food intake and whole‐body physiology were assessed and serum/tissues analyzed biochemically. Methionine restriction in 12‐month‐old mice completely reversed age‐induced alterations in body weight, adiposity, physical activity, and glucose tolerance to the levels measured in healthy 2‐month‐old control‐fed mice. This was despite a significant increase in food intake in 12‐month‐old MR‐fed mice. Methionine restriction decreased hepatic lipogenic gene expression and caused a remodeling of lipid metabolism in white adipose tissue, alongside increased insulin‐induced phosphorylation of the insulin receptor (IR) and Akt in peripheral tissues. Mice restricted of methionine exhibited increased circulating and hepatic gene expression levels of FGF21, phosphorylation of eIF2a, and expression of ATF4, with a concomitant decrease in IRE1α phosphorylation. Short‐term 48‐h MR treatment increased hepatic FGF21 expression/secretion and insulin signaling and improved whole‐body glucose homeostasis without affecting body weight. Our findings suggest that MR feeding can reverse the negative effects of aging on body mass, adiposity, and insulin resistance through an FGF21 mechanism. These findings implicate MR dietary intervention as a viable therapy for age‐induced metabolic syndrome in adult humans.  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