全文获取类型
收费全文 | 1525篇 |
免费 | 38篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 3篇 |
妇产科学 | 1篇 |
基础医学 | 87篇 |
口腔科学 | 15篇 |
临床医学 | 53篇 |
内科学 | 99篇 |
皮肤病学 | 3篇 |
神经病学 | 88篇 |
特种医学 | 22篇 |
外科学 | 24篇 |
综合类 | 133篇 |
预防医学 | 103篇 |
眼科学 | 7篇 |
药学 | 761篇 |
中国医学 | 132篇 |
肿瘤学 | 47篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 25篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 74篇 |
2013年 | 80篇 |
2012年 | 112篇 |
2011年 | 139篇 |
2010年 | 133篇 |
2009年 | 120篇 |
2008年 | 111篇 |
2007年 | 95篇 |
2006年 | 72篇 |
2005年 | 68篇 |
2004年 | 62篇 |
2003年 | 52篇 |
2002年 | 52篇 |
2001年 | 37篇 |
2000年 | 27篇 |
1999年 | 16篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 13篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
排序方式: 共有1580条查询结果,搜索用时 15 毫秒
1.
2.
谷氨酰胺在危重病患者中的应用 总被引:3,自引:0,他引:3
目的探讨危重病患者中早期经静脉应用谷氨酰胺(glutamine,Gl)的临床价值。方法42例患者随机分成两组(对照组和Gln组),Gln组进行Gln治疗(100mL/d,共7d)。治疗前后检测患者体质量、白蛋白、谷胱甘肽(GSH)、握力的变化和肠功能不全的发生率。结果体质量两组治疗前后比较差异无显著性(P〉0.05)。白蛋白、握力和GSH Gl治疗后非常显著高于治疗前(P〈0.01);白蛋白对照组治疗后较治疗前显著增高(P〈0.05),但握力和GSH治疗前后均无显著变化(P〉0.05);肠功能不全的发生率Gln组为4.8%,显著低于对照组(28.6%,P〈0.05)。结论在危重病患者疾病早期通过静脉途径外源性地补充Gln,有效改善了患者的营养状况;使患者血浆中的GSH水平增高,加强了机体的抗氧化能力;减少了患者肠功能不全的发生率。 相似文献
3.
目的:观察采用谷氨酰半胱氨酸合成酶抑制剂--丁胱亚磺酰亚胺(BSO)排空大鼠心肌谷胱甘肽(GSH)是否影响大鼠心肌组织GSH的稳态,以及是否对GSH代谢相关酶活性及mRNA表达产生影响.方法:采用长时间力竭运动、注射BSO排空GSH两种实验模型,比较对照组与注射BSO组SD大鼠心肌在静息状态和长时间力竭运动后GSH状态及其代谢变化.结果:注射BSO 8天后,大鼠心脏GSH含量分别为对照组?%,且GSH的下降伴随着氧化型谷胱甘肽(GSSG)的下降,GSH/GSSG的比值无显著变化.GSH排空导致GSH代谢酶活性发生适应性变化,注射BSO后心肌中谷胱甘肽过氧化物酶(GPX)活性与对照组相比显著下降(P < 0.001).注射BSO组与对照组相比,心肌谷氨酰转肽酶(GGT)活性显著增加(P < 0.05).注射BSO力竭组与注射BSO组相比,心肌GGT活性显著增加(P < 0.001),心肌注射BSO抑制γ-谷氨酰半胱酸合成酶(GCS)活性,注射BSO力竭组大鼠心肌GCS mRNA表达量高于注射BSO组,表明极度排空谷胱甘肽后,GCS mRNA表达量的增加可能是机体产生的应激反应. 相似文献
4.
Thiols decrease cytokine levels and down-regulate the expression of CD30 on human allergen-specific T helper (Th) 0 and Th2 cells
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bengtsson A Lundberg M Avila-Cariño J Jacobsson G Holmgren A Scheynius A 《Clinical and experimental immunology》2001,123(3):350-360
The thiol antioxidant N-acetyl- L-cysteine (NAC), known as a precursor of glutathione (GSH), is used in AIDS treatment trials, as a chemoprotectant in cancer chemotherapy and in treatment of chronic bronchitis. In vitro, GSH and NAC are known to enhance T cell proliferation, production of IL-2 and up-regulation of the IL-2 receptor. The 120-kD CD30 surface antigen belongs to the tumour necrosis factor (TNF) receptor superfamily. It is expressed by activated T helper (Th) cells and its expression is sustained in Th2 cells. We have analysed the effect of GSH and NAC on the cytokine profile and CD30 expression on human allergen-specific T cell clones (TCC). TCC were stimulated with anti-CD3 antibodies in the presence of different concentrations of GSH and NAC. Both thiols caused a dose dependent down-regulation of IL-4, IL-5 and IFN-gamma levels in Th0 and Th2 clones, with the most pronounced decrease of IL-4. Furthermore, they down-regulated the surface expression of CD30, and the levels of soluble CD30 (sCD30) in the culture supernatants were decreased. In contrast, the surface expression of CD28 or CD40 ligand (CD40L) was not significantly changed after treatment with 20 m M NAC. These results indicate that GSH and NAC favour a Th1 response by a preferential down-regulation of IL-4. In addition, the expression of CD30 was down regulated by GSH and NAC, suggesting that CD30 expression is dependent on IL-4, or modified by NAC. In the likely event that CD30 and its soluble counterpart prove to contribute to the pathogenesis in Th2 related diseases such as allergy, NAC may be considered as a future therapeutic agent in the treatment of these diseases. 相似文献
5.
Reactive oxygen species (ROS), represented by superoxide, hydrogen peroxide and hydroxyl radicals, have been implicated in many diseases including cancer. ROS have been known to play an important role in the initiation and promotion of multistep carcinogenesis. The cellular antioxidants play a crucial role in protection against neoplastic disease. However, very little is known about the antioxidant defense in cervical carcinoma. This is addressed in the present study. Lipid peroxides, glutathione content and the activities of antioxidant enzymes, together with vitamin C and E content, were estimated in patients who had carcinoma of the cervix, and the values were compared with those of normal women. The results showed a remarkable reduction in the content of glutathione, vitamin E and C. Activities of glutathione peroxidase and superoxide dismutase were also reduced in cervical cancer compared to normal controls (P < 0.001). This reduction was more marked in late stages (III, IV) than in early stages (I, II) (P < 0.001). Glutathione was reduced more in poorly differentiated tumors (grade III) than in well and moderately differentiated ones (grade I, II) (P < 0.05). Levels of lipid peroxides were found to be significantly higher in malignant than in normal tissue samples and their levels were correlated with advanced clinical stage (P < 0.001). Our results suggest impaired antioxidant status in carcinoma of the cervix. This impairment is related to tumor progression. 相似文献
6.
HepG2 细胞谷胱甘肽含量和谷胱甘肽转移酶活力的诱导 总被引:1,自引:0,他引:1
陈立 《天津医科大学学报》2000,6(3):265-267
目的:建立一种具有较高GSH含量和GST活力的肝细胞系。方法:将HepG2细胞在0.1,0.3,0.5mg/L浓度的CDDP间歇作用下传代12个月后得到三种稳定的CDDP耐药细胞系HepG2/CDDP0.1,HepG2/CDDP0.3,HepG2/CDDP0.5细胞的GSH含量和GST活力,结果用显著性t检验方法作统计学处理。结果:诱导刺激后的子代HepG2/CDDP0.1,HepG2/CDDP0 相似文献
7.
K. Buser F. Joncourt H.-J. Altermatt M. Bacchi A. Oberli Th. Cerny 《Annals of oncology》1997,8(4):335-341
Background: The identification of new factors predicting relapse,outcome and response to systemic therapy in breast cancer is warranted. Themeasurement of biological markers such as drug resistance parameters (DRPs),which are part of the phenotype of malignant cells and contribute toresistance to anti-cancer drugs may be a possibility, which may ultimatelylead to improvement of therapeutic results.Patients and methods: The level of glutathione (GSH), activities ofglutathione-S-transferase (GST), glutathione-peroxidase (GPx),06-alkylguanine-DNA-alkyltransferase (ATase), and P-glycoprotein (PGP) weremeasured in tumor and adjacent tumor free tissue samples from 89 consecutive,untreated females with breast cancer and correlated with clinical andprognostic factors. Early breast cancer (EBC) was diagnosed in 56 patients,22 patients had locally advanced (LABC) and 11 patients metastatic breastcancer.Results: All DRPs showed significantly higher expression in tumorthan in tumor free tissues. GPx was positively correlated with GST (R = 0.3, P = 0.0048) and with GSH (R = 0.5, P = 0.0001) in tumor as wellas in normal tissue. GST activity was significantly higher in EBC than in LABCor metastatic breast cancer ( P = 0.02). GSH level was significantlyhigher in grade 1 than in grade 2 or grade 3 tumors ( P = 0.01). Whenclinical characteristics were related to the level of DRP, high GSH wasassociated with age >60 years ( P = 0.01) in EBC, and with grade1–2 tumors ( P = 0.05) in LABC. No differences in OS were apparentbetween groups of high and low DRP-expression. However, the four-yearestimated disease-free survival of EBC tended to be higher in patients withhigh GST ( P = 0.10) and of LABC in patients with high GPx levels( P = 0.06).Conclusion: We conclude that high levels of DRP in tumor tissue ofbreast cancer patients are part of the initial phenotype of the malignantcells. Due to its high prevalence (83% in EBC, 100% in primarilymetastatic breast cancer), PGP did not add to prognostic information. Highlevels of GSH, GST and and GPx were associated with favorable clinicalcharacteristics and good prognosis, whereas low levels of GSH and GST activitywere associated with more aggressive or more advanced disease. 相似文献
8.
15kg负重沙漠干热应激行军速度和时间对人体GSH和SOD的影响 总被引:1,自引:0,他引:1
目的 探讨沙漠干热负重应激行军人体GSH 和SOD 作用机制。方法 对74 名15 kg 负重在沙漠干热环境以不同速度和时间行军战士和对照人群血浆的变化进行了研究。结果 15 kg 负重,3-5km/h 和5 km/h 行军者GSH 在应激的最初1 小时内迅速上升,约1 小时达到高峰,之后迅速下降;随着行军速度的增加,机体抗氧化作用所消耗的SOD 量增加,血浆SOD 浓度亦随之下降。结论 从行军时间来看,在应激的最初1 小时内,因应激诱导的GSH 的合成和SOD 的量增加,故沙漠干热环境负荷应激行军以15 kg、3-5 km/h 为宜。 相似文献
9.
砷对小鼠脂质过氧化和抗氧化能力的影响 总被引:14,自引:1,他引:13
采用动物实验方法,研究砷对小鼠各组织MDA含量,SOD活力及全血GSH-Px活力的影响。结果显示:心脏的中、高剂量组MDA水平显著高于对照组和低剂量组,而SOD活力则是中、高剂量组显著低于对照组和低剂量组;肝脏的染毒组MDA水平均显著高于对照组,而SOD活力低剂量组显著高于其它3组,中、高剂量组显著低于对照组和低剂量组;肾脏中仅高剂量组MDA水平显著高于对照组,而SOD活力各组间无显著差异。全血中的GSH-Px活力显著下降,并呈剂量-效应关系。表明,砷可促进机体脂质过氧化,抑制抗氧化酶(SOD,GSH-Px)的活力。 相似文献
10.
谷胱甘肽对汞致肾细胞凋亡影响的实验研究 总被引:2,自引:0,他引:2
目的 探讨谷胱甘肽(GSH)对汞致肾细胞凋亡的影响,进一步阐明无机汞肾损伤的分子机制。方法 昆明种小鼠24只随机分成3组,即对照组、单纯汞染毒组和GSH干预组。单纯汞染毒组小鼠腹腔注射3.0mg/kg氯化汞(HgCl2)溶液,对照组腹腔注射0.9%的氯化钠溶液,注射量为每10g体重注射0.2ml。GSH干预组于注射3.0mg/kg,HgCl2溶液前2h腹腔注射3mmol/kg谷胱甘肽溶液。24h后将小鼠颈椎错位处死,制备透射电镜标本,观察凋亡细胞形态;免疫组化法检测凋亡相关基因bcl-2和bax蛋白表达。制备单细胞悬液,用流式细胞仪进行凋亡细胞百分数分析。结果 对照组小鼠肾近曲小管细胞形态规则;单纯汞染毒组表现微绒毛排列紊乱,染色质聚集成块,核破碎释放出凋亡小体,凋亡小体被邻近细胞吞噬等典型细胞凋亡形态;GSH干预组显示接近正常的肾小管上皮细胞的形态。凋亡细胞百分数汞染毒组明显高于对照组(P〈0.01),GSH干预组明显低于汞染毒组(P〈0.01)。免疫组化检测GSH干预组bcl-2蛋白的表达明显高于汞染毒组(P〈0.01);bax蛋白的表达显著低于汞染毒组(P〈0.01)。结论 GSH可以抵抗汞所致的肾细胞凋亡,使凋亡相关基因bcl-2蛋白的表达上调,bax蛋白的表达下调。 相似文献