全文获取类型
收费全文 | 457篇 |
免费 | 28篇 |
国内免费 | 17篇 |
专业分类
妇产科学 | 8篇 |
基础医学 | 85篇 |
口腔科学 | 6篇 |
临床医学 | 17篇 |
内科学 | 58篇 |
皮肤病学 | 3篇 |
神经病学 | 19篇 |
特种医学 | 4篇 |
外科学 | 22篇 |
综合类 | 52篇 |
预防医学 | 14篇 |
眼科学 | 6篇 |
药学 | 106篇 |
中国医学 | 64篇 |
肿瘤学 | 38篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 34篇 |
2013年 | 33篇 |
2012年 | 25篇 |
2011年 | 54篇 |
2010年 | 48篇 |
2009年 | 43篇 |
2008年 | 41篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 30篇 |
2003年 | 15篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
排序方式: 共有502条查询结果,搜索用时 62 毫秒
21.
本文探讨外源性重组人钙调素(recombinant human calmodulin,rhCaM)对人脐静脉内皮细胞(HUVEC)增殖作用的影响。采用基因重组技术在大肠杆菌DH5α中高效表达并纯化rhCaM。将HUVEC接种于96孔培养板,加入不同浓度rhCaM,用MTT比色法检测rhCaM对HUEVC细胞增殖作用的影响。结果表明rhCaM在0.04~0.4μg/ml浓度范围内可促进HUEVC的增殖,促增殖作用随细胞培养密度的增加而减弱,也与培养基中新生小牛血清的含量密切相关。故rhCaM对HUEVC增殖具有促进作用。 相似文献
22.
Kusche-Vihrog K Sobczak K Bangel N Wilhelmi M Nechyporuk-Zloy V Schwab A Schillers H Oberleithner H 《Pflügers Archiv : European journal of physiology》2008,455(5):849-857
The amiloride-sensitive epithelial sodium channel (ENaC) is usually found in the apical membrane of epithelial cells but has
also recently been described in vascular endothelium. Because little is known about the regulation and cell surface density
of ENaC, we studied the influence of aldosterone, spironolactone, and amiloride on its abundance in the plasma membrane of
human endothelial cells. Three different methods were applied, single ENaC molecule detection in the plasma membrane, quantification
by Western blotting, and cell surface imaging using atomic force microscopy. We found that aldosterone increases the surface
expression of ENaC molecules by 36% and the total cellular amount by 91%. The aldosterone receptor antagonist spironolactone
prevents these effects completely. Acute application of amiloride to aldosterone-pretreated cells led to a decline of intracellular
ENaC by 84%. We conclude that, in vascular endothelium, aldosterone induces ENaC expression and insertion into the plasma
membrane. Upon functional blocking with amiloride, the channel disappears from the cell surface and from intracellular pools,
indicating either rapid degradation and/or membrane pinch-off. This opens new perspectives in the regulation of ENaC expressed
in the vascular endothelium. 相似文献
23.
Zhang Lu Wu Lili Liu Ximing Yoshitomi Hisae Ikeda Katsumi Negishi Hiroko Pan Yajing Sun Wen Qin Lingling Li Juan-E Xu Tunhai Liu Tonghua Gao Ming 《中医杂志(英文版)》2018,38(4):548-555
OBJECTIVE
To evaluate whether endothelial dysfunction and hypertension are prevented by trans-cinnamaldehyde (tCA) through the activation of endothelial nitric oxide synthase (eNOS).METHODS
Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and stimulated with tCA to determine cell viability using the methyl thiazolyl tetrazolium assay. The effect of tCA on nitric oxide (NO) production was determined by diaminofluorescein-dyes in the absence or presence of inhibitors of eNOS, AMPK, PKA, and AKT. The effect of tCA on blood pressure was determined by the tail-cuff method in obesity spontaneous hypertension (SHR. Cg-Leprcp/NDmcr) rats. The phosphorylation of eNOS and protein expression of the insulin-signaling pathway (InsR-IRS1-PI3K-AKT) were measured by western blot.RESULTS
tCA at concentrations less than 100 did not affect cell viability in cultured HUVECs. Stimulation with tCA promoted NO release in a time-dependent manner compared with the control group. tCA-treated HUVECs also significantly increased AKT-Ser473 and eNOS- Ser1177 phosphorylation. In SHR-CP rats, treatment with tCA at a dose of 40 mg/kg/day for 6 weeks markedly reduced the systolic blood pressure and diastolic blood pressure, increased the phosphorylation of AKT and eNOS, and increased urinary nitric oxidation.CONCLUSION
tCA attenuated endothelial dysfunction and reduced blood pressure in SHR-CP rats. The underlying mechanisms may involve the increase in AKT and eNOS phosphorylation and the release of eNOS-derived NO. 相似文献24.
pCDNA3.0载体介导METH1基因对人脐静脉内皮细胞生长的抑制 总被引:6,自引:0,他引:6
目的研究METH1基因对人脐静脉内皮细胞(HUVEC)体外生长的抑制作用。方法构建真核表达载体pCDNA3.0-METH1,转染肝癌细胞系HepG2中。体外扩增HUVEC,采用MTT法检测HepG2/METH1及HepG2培养的上清对HUVEC增殖的影响。结果成功的构建了真核表达载体pCDNA3.0-METH1,并在HepG2中稳定表达。MTT法结果显示与对照组相比,HepG2/METH1组对HUVEC增殖有明显的抑制作用,并呈剂量依赖性(P<0.01);而HepG2组对HUVEC增殖有明显的促进作用,呈剂量依赖性(P<0.05)。结论pCDNA3.0-METH1对HUVEC体外生长具有明显的抑制作用,提示METH1对瘢痕内血管的抑制治疗具有潜在的临床应用价值。 相似文献
25.
目的探讨缸鱼软骨多糖(RCG)对人脐静脉内皮细胞形成新生血管的作用.方法原代培养人脐静脉内皮细胞,实验分为生理氯化钠溶液(NS)对照组、RCG 100,50,25,10,2 g·L-1组和阳性对照鲨鱼软骨多糖(SCG,50 g·L-1)组.采用MTT法检测RCG对HUVEC增殖的影响,流式细胞仪检测RCG对HUVEC细胞周期的影响;并观察RCG对HUVEC迁移及小管形成的作用.结果10~100 g·L-1RCG可明显抑制HUVEC的体外增殖,IC50为62.93 g·L-1.流式细胞仪检测表明,RCG阻止HUVEC在G2/M期.10~100g·L-1 RCG明显抑制HUVEC迁移和小管形成.结论RCG具有良好的体外抗血管生成活性. 相似文献
26.
内皮细胞生长因子的分离纯化及生物活性的研究 总被引:5,自引:2,他引:3
介绍了内皮细胞生长因子(ECGF)一种分离纯化的方法,经硫酸铵分级盐析和肝素亲和层析可得到高纯度的ECGF。经SDS—PAGE电泳分析其分子量为17000,等电点为4.8。肝素与ECGF的生物活性密切相关,并可使已失活的(ECGF)恢复70%~80%的生物活性。 相似文献
27.
Dose-dependent activation of Ca2+-activated K+ channels by ethanol contributes to improved endothelial cell functions 总被引:1,自引:0,他引:1
Kuhlmann CR Li F Lüdders DW Schaefer CA Most AK Backenköhler U Neumann T Tillmanns H Waldecker B Erdogan A Wiecha J 《Alcoholism, clinical and experimental research》2004,28(7):1005-1011
BACKGROUND: Regular moderate alcohol (EtOH) intake seems to protect against both coronary artery disease and ischemic stroke, whereas the risk increases with heavy EtOH consumption. Effects of EtOH on endothelial cell function may be relevant to these disparate effects. Potassium channels play an important role in the regulation of endothelial cell functions. Therefore, we investigated whether Ca-activated K channels (BKCa) are modulated by EtOH. Furthermore, we examined whether EtOH-induced changes of endothelial nitric oxide (NO) formation and cell proliferation are due to BKCa activation. METHODS: The patch-clamp technique was used to investigate BKCa activity in cultured human umbilical vein endothelial cells (HUVEC). NO formation was analyzed by using the fluorescence dye 4,5-diaminofluorescein. Endothelial proliferation was examined by using cell counts and measuring [H]thymidine incorporation. RESULTS: EtOH dose-dependently (10-150 mmol/liter) modulated BKCa-activity, with the highest increase of open-state probability at a concentration of 50 mmol/liter (n = 13; p < 0.05). Inside-out recordings revealed that this effect was due to direct BKCa activation, whereas open-state probability was not changed in cell-attached recordings after pertussis toxin preincubation. EtOH (10 and 50 mmol/liter) caused a significant increase of NO levels, which was blocked by the highly selective BKCa inhibitor iberiotoxin (100 nmol/l; n = 30; p < 0.05). Higher concentrations of EtOH (100 and 150 mmol/liter) significantly reduced NO synthesis (n = 30; p < 0.05). Both methods revealed a significant increase of HUVEC proliferation, which was inhibited by iberiotoxin (n = 30; p < 0.05). At a concentration of 150 mmol/liter, EtOH caused a significant reduction of endothelial proliferation. CONCLUSIONS: EtOH directly activates BKCa in HUVEC, leading to an increase of endothelial proliferation and production of NO. These results indicate a possible beneficial effect of low-dose EtOH on endothelial function, whereas higher concentrations must be considered as harmful. 相似文献
28.
Knoll T Steidler A Trojan L Sagi S Schaaf A Yard B Michel MS Alken P 《Urological research》2004,32(4):304-309
Most renal stones in humans are composed of calcium oxalate. An increase in urinary oxalate levels has been shown to result in renal epithelial cell injury and crystal retention. However, the underlying mechanisms are unclear. Although the localization of primary stone formation and the associated cells playing the pivotal role in stone formation are still unknown, renal epithelial cells and interstitial cells seem to be involved in this process. The aim of this study was to evaluate the effects of oxalate on distinct renal epithelial and endothelial cells as well as fibroblasts. The first part focused on the toxicity of oxalate on the cells and a potential time- and dose-dependency. In the second part, renal epithelial cells were cultured in a two-compartment model to examine the vulnerability of the tubular or basolateral side to oxalate. LLCPK1, MDCK, renal fibroblast and endothelial cell lines were cultured under standard conditions. In part 1, cells were grown in standard culture flasks until confluent layers were achieved. Sodium oxalate was delivered at final concentrations of 1, 2 and 4 mM to either the apical or basolateral side (plain medium was delivered to the contralateral side). Cell survival was assessed microscopically by trypan blue staining after 1, 2 and 4 h. The influence of oxalate on proliferation and apoptosis induction was also investigated. In the second part, MDCK and LLCPK1 cells were grown in 6-well plates until confluent layers were achieved. Sodium oxalate at the above concentrations was applied, to either the apical or basolateral side and plain medium was delivered to the opposite side. The same protocol was then followed as in part 1. Part 1: sodium oxalate led to a time- and concentration-dependent decline in cell survival that was comparable in LLCPK1 and MDCK. Non-tubular cell lines like fibroblasts and endothelial cells were significantly more vulnerable to oxalate. These observations were reflected by significant impairment to cell proliferation. We could not demonstrate an induction of apoptosis in any cell line. Part 2: both cell lines were more vulnerable to oxalate on the basolateral side. This effect was more pronounced in MDCK cells at high oxalate concentrations (4 mM). Cells are apparently more resistant on the apical (tubular) side. Our results show that sodium oxalate has a negative effect on the growth and survival of renal epithelial cells and, to a greater extent, also fibroblasts and endothelial cells. We could not demonstrate any induction of apoptotic processes which implies a direct induction of cell necrosis. The finding of interstitial calcification and the proximity of tubules, vessels and interstitial cells make involvement of non-tubular renal cells in tissue calcification processes possible. Renal epithelial cells are apparently more vulnerable to oxalate on their basolateral side. Therefore, calcification processes within the interstitium may exert pronounced toxic effects to these cells, leading to inflammation and necrosis. These observations further support the idea of the interstitium as a site of primary stone formation. 相似文献
29.
Effects of the selective COX-2 inhibitors celecoxib and rofecoxib on human vascular cells 总被引:3,自引:0,他引:3
Niederberger E Manderscheid C Grösch S Schmidt H Ehnert C Geisslinger G 《Biochemical pharmacology》2004,68(2):341-350
Rheumatoid arthritis (RA) is associated with a reduced life expectancy considered to be partly caused by cardiovascular events. A growing concern is that accelerated atherosclerosis is driven by inflammatory mechanisms similar to those responsible for RA. Therefore, selective COX-2 inhibitors, which are widely used for the symptomatic treatment of pain and inflammation in RA, may have an impact on atherosclerotic processes. Their anti-inflammatory properties might provoke anti-atherogenic effects but on the other hand, selective inhibition of anti-thrombotic prostacyclin and COX-2 independent effects might promote the risk of increased prothrombotic activity. In the current study, the effects of the presently marketed selective COX-2 inhibitors celecoxib and rofecoxib on vascular cells have been investigated. Celecoxib inhibited the proliferation of human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. At high concentrations, it induced apoptosis and the modulation of inhibitory cell cycle proteins. In contrast rofecoxib-even at high concentrations-had no effect on cell proliferation, apoptosis or cell cycle distribution indicating that celecoxib and rofecoxib do not affect the same signal transduction pathways in endothelial cells. Both drugs did not affect apoptosis induction or cell cycle proliferation in human vascular smooth muscle cells. The observed effects on endothelial cells appear to be COX-independent since both drugs selectively inhibited COX-2-activity and the applied concentrations lay beyond the IC(50) for inhibition of prostacyclin production. Regarding endothelial apoptosis as a relevant event in the initiation and progression of atherosclerosis the present data put forward the hypothesis that the presently marketed COX-2 inhibitors have a different impact on atherosclerotic processes. 相似文献
30.
Polyacetylenes Function as Anti-Angiogenic Agents 总被引:1,自引:0,他引:1
Wu LW Chiang YM Chuang HC Wang SY Yang GW Chen YH Lai LY Shyur LF 《Pharmaceutical research》2004,21(11):2112-2119
PURPOSE: To investigate the antiangiogenic effects of plant extracts and polyacetylenes isolated from Bidens pilosa Linn., which is a popular nutraceutical herbal tea and folk medicine in anti-inflammatory, antitumor, and other medications worldwide. METHODS: Anti-cell proliferation, anti-tube formation, and cell migration assays were used for the valuation of bioactivities of target plant extracts and phytocompounds against angiogenesis. Bioactivity-guided fractionation, HPLC, and various spectral analyses were used to identify active fraction and phytocompounds for anti-angiogenesis. RESULTS: We show that an ethyl acetate (EA) fraction of B. pilosa exhibited significant anti-cell proliferation and anti-tube formation activities against human umbilical vein endothelium cells (HUVEC). Bioassay-guided fractionation led to isolation of one new and one known polyacetylenes, 1,2-dihydroxytrideca-5,7,9,11-tetrayne (1) and 1,3-dihydroxy-6(E)- tetradecene-8,10,12-triyne (2), respectively, from the EA fraction. Compounds 1 and 2 manifested highly specific and significant activities against HUVEC proliferation with IC50 values of 2.5 and 0.375 microg/ml, respectively, however, compound 1 had a more potent effect on preventing tube formation of HUVEC than compound 2 at a dose of 2.5 microg/ml. Western blot analysis showed that both compounds upregulated p27(Kip) or p21(Cip1), cyclin-dependent kinase inhibitors, in HUVEC. CONCLUSIONS: This is the first report to demonstrate that polyacetylenes possess significant anti-angiogenic activities and the ability to regulate the expression of cell cycle mediators, for example, p27(Kip1), p21(Cip1), or cyclin E. 相似文献