全文获取类型
收费全文 | 3428篇 |
免费 | 347篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 18篇 |
儿科学 | 54篇 |
妇产科学 | 49篇 |
基础医学 | 626篇 |
口腔科学 | 258篇 |
临床医学 | 274篇 |
内科学 | 637篇 |
皮肤病学 | 71篇 |
神经病学 | 227篇 |
特种医学 | 173篇 |
外科学 | 312篇 |
综合类 | 5篇 |
一般理论 | 2篇 |
预防医学 | 262篇 |
眼科学 | 8篇 |
药学 | 301篇 |
中国医学 | 2篇 |
肿瘤学 | 525篇 |
出版年
2023年 | 21篇 |
2022年 | 17篇 |
2021年 | 51篇 |
2020年 | 41篇 |
2019年 | 61篇 |
2018年 | 64篇 |
2017年 | 57篇 |
2016年 | 77篇 |
2015年 | 61篇 |
2014年 | 89篇 |
2013年 | 129篇 |
2012年 | 197篇 |
2011年 | 163篇 |
2010年 | 113篇 |
2009年 | 88篇 |
2008年 | 161篇 |
2007年 | 142篇 |
2006年 | 140篇 |
2005年 | 154篇 |
2004年 | 151篇 |
2003年 | 162篇 |
2002年 | 178篇 |
2001年 | 149篇 |
2000年 | 139篇 |
1999年 | 123篇 |
1998年 | 66篇 |
1997年 | 57篇 |
1996年 | 68篇 |
1995年 | 61篇 |
1994年 | 36篇 |
1993年 | 32篇 |
1992年 | 70篇 |
1991年 | 66篇 |
1990年 | 84篇 |
1989年 | 83篇 |
1988年 | 55篇 |
1987年 | 41篇 |
1986年 | 34篇 |
1985年 | 38篇 |
1984年 | 44篇 |
1983年 | 33篇 |
1982年 | 32篇 |
1981年 | 17篇 |
1980年 | 21篇 |
1979年 | 25篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 12篇 |
1975年 | 16篇 |
1974年 | 11篇 |
排序方式: 共有3804条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Carrier-mediated transport in the hepatic distribution and elimination of drugs, with special reference to the category of organic cations 总被引:1,自引:0,他引:1
D K Meijer W E Mol M Müller G Kurz 《Journal of pharmacokinetics and biopharmaceutics》1990,18(1):35-70
Carrier-mediated transport of drugs occurs in various tissues in the body and may largely affect the rate of distribution and elimination. Saturable translocation mechanisms allowing competitive interactions have been identified in the kidneys (tubular secretion), mucosal cells in the gut (intestinal absorption and secretion), choroid plexus (removal of drug from the cerebrospinal fluid), and liver (hepatobiliary excretion). Drugs with quaternary and tertiary amine groups represent the large category of organic cations that can be transported via such mechanisms. The hepatic and to a lesser extent the intestinal cation carrier systems preferentially recognize relatively large molecular weight amphipathic compounds. In the case of multivalent cationic drugs, efficient transport only occurs if large hydrophobic ring structures provide a sufficient lipophilicity-hydrophilicity balance within the drug molecule. At least two separate carrier systems for hepatic uptake of organic cations have been identified through kinetic and photoaffinity labeling studies. In addition absorptive endocytosis may play a role that along with proton-antiport systems and membrane potential driven transport may lead to intracellular sequestration in lysosomes and mitochondria. Concentration gradients of inorganic ions may represent the driving forces for hepatic uptake and biliary excretion of drugs. Recent studies that aim to the identification of potential membrane carrier proteins indicate multiple carriers for organic anions, cations, and uncharged compounds with molecular weights around 50,000 Da. They may represent a family of closely related proteins exhibiting overlapping substrate specificity or, alternatively, an aspecific transport system that mediates translocation of various forms of drugs coupled with inorganic ions. Consequently, extensive pharmacokinetic interactions can be anticipated at the level of uptake and secretion of drugs regardless of their charge. 相似文献
5.
We studied a possible acinar heterogeneity in the transport of organic cations, using rhodamine B as model compound. Employing perfusions of isolated rat livers in the ante- and retrograde mode and quantitative fluorescence microscopy, Zones 1 and 3 were shown to be equally efficient in taking up rhodamine B. Ten minutes after injection in an antegrade perfusion, 95% of the dose was localized in the portal half of the acinus. Fifty minutes later, however, the amount of rhodamine B in Zone 1 had been reduced to 23%; 30 and 31% were in Zones 2 and 3, respectively, and the medium concentration was doubled. Thus, unchanged rhodamine B appeared to be transported downstream within the liver, either via the medium or directly from cell to cell, finally resulting in a relatively higher rhodamine B concentration in Zone 3. To obtain additional data, we designed a perfusion setup in which the zones could be studied separately. In both zones, the amount excreted into the medium was about 30 times the amount excreted into bile. Intracellular sequestration of rhodamine B and the rate constant for sinusoidal secretion were higher in Zone 3, while the sinusoidal uptake rates were equal; biliary excretion was higher in Zone 1. Acinar distribution changed with time because rhodamine B, primarily accumulated in Zone 1, was secreted into the sinusoids and taken up again by downstream cells. The finally higher rhodamine B concentration in Zone 3 was caused by a zonal heterogeneity in intracellular sequestration and sinusoidal secretion of rhodamine B. 相似文献
6.
偏头痛大鼠脑内5-羟色胺1F和诱导型一氧化氮合酶基因的表达变化及针刺的干预效应 总被引:3,自引:0,他引:3
目的:前期实验已证实针刺治疗偏头痛疗效优越。观察针刺对偏头痛大鼠脑内5-羟色胺1F和诱导型一氧化氮合酶mRNA表达的调控作用。方法:实验于2005-11/2006-05在中南大学湘雅医院中西医结合研究所实验室完成。①选用SD大鼠40只,按随机数字表法分为4组(n=10),除正常对照组外,其余3组均复制大鼠偏头痛模型。模型对照组只造模,不作其他处理;针刺治疗组造模后进行针刺;针刺预防组针刺后造模电刺激20min。针刺方法:针刺大鼠双侧太冲、阳陵泉穴20min。采用疏密波,电流强度0.3~0.6mA,留针20min,1次/d,共5次。②实验完毕后取脑干及三叉神经节匀浆,采用反转录-聚合酶链反应法测定5-羟色胺1F和诱导型一氧化氮合酶mRNA表达。结果:进入结果分析正常对照组10只,模型对照组、针刺治疗组、针刺预防组各9只,共脱失3只。①与正常对照组比较,模型对照组大鼠诱导型一氧化氮合酶mRNA表达显著增强(P<0.01),5-羟色胺1FmRNA表达显著减弱(P<0.01)。②与模型对照组比较,针刺预防组和针刺治疗组诱导型一氧化氮合酶mRNA表达明显减弱(P<0.01),5-羟色胺1FmRNA表达显著增强(P<0.01)。结论:针刺调控5-羟色胺1F和诱导型一氧化氮合酶mRNA的表达可能是针刺防治偏头痛的分子机制。 相似文献
7.
Ingestion of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli by human peritoneal mesothelial cells. 下载免费PDF全文
C E Visser J J Brouwer-Steenbergen I L Schadee-Eestermans S Meijer R T Krediet R H Beelen 《Infection and immunity》1996,64(8):3425-3428
In the present study we examined whether mesothelial cells can ingest and digest bacteria. The results showed that all strains were ingested. Ingested staphylococci proliferated abundantly, and only a few were digested. Escherichia coli, however, was digested during the first 8 h, whereafter the mesothelial cells disintegrated and proliferation of bacteria could be observed. The clinical implications of these findings are discussed. 相似文献
8.
9.
G van Ingen H van Bronswijk C J Meijer H V Stel 《The Netherlands journal of medicine》1991,39(3-4):142-147
A patient presenting with a nephrotic syndrome and chronic renal failure caused by light chain deposition disease (LCDD) without detectable light chains in serum and urine is presented. Only a few patients with LCDD but without detectable light chains in serum and urine have hitherto been reported. The diagnosis was made by light-microscopic and immunofluorescent examination of a percutaneous renal biopsy. The histological differential diagnosis of LCDD includes diabetic glomerulosclerosis, renal amyloidosis and membranoproliferative glomerulonephritis. For the histological diagnosis of LCDD, immunofluorescence using anti-kappa and anti-lambda antisera is essential. Although renal involvement is a constant feature in LCDD, other sites of deposition of light chains have been reported. The absence of detectable light chains in serum or urine is discussed. 相似文献
10.
Retrorenal colon: implications for percutaneous diskectomy 总被引:1,自引:0,他引:1
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary. 相似文献