全文获取类型
收费全文 | 392791篇 |
免费 | 27489篇 |
国内免费 | 12944篇 |
专业分类
耳鼻咽喉 | 4273篇 |
儿科学 | 10276篇 |
妇产科学 | 4942篇 |
基础医学 | 45149篇 |
口腔科学 | 7221篇 |
临床医学 | 39494篇 |
内科学 | 68869篇 |
皮肤病学 | 5499篇 |
神经病学 | 24288篇 |
特种医学 | 16117篇 |
外国民族医学 | 72篇 |
外科学 | 44925篇 |
综合类 | 44033篇 |
现状与发展 | 43篇 |
一般理论 | 6篇 |
预防医学 | 22704篇 |
眼科学 | 6167篇 |
药学 | 50096篇 |
122篇 | |
中国医学 | 11974篇 |
肿瘤学 | 26954篇 |
出版年
2024年 | 645篇 |
2023年 | 5092篇 |
2022年 | 9422篇 |
2021年 | 18679篇 |
2020年 | 12065篇 |
2019年 | 16265篇 |
2018年 | 11282篇 |
2017年 | 10730篇 |
2016年 | 12688篇 |
2015年 | 15905篇 |
2014年 | 27167篇 |
2013年 | 26470篇 |
2012年 | 28065篇 |
2011年 | 26604篇 |
2010年 | 23562篇 |
2009年 | 23634篇 |
2008年 | 21977篇 |
2007年 | 21350篇 |
2006年 | 18571篇 |
2005年 | 14033篇 |
2004年 | 9324篇 |
2003年 | 8307篇 |
2002年 | 6614篇 |
2001年 | 5494篇 |
2000年 | 4792篇 |
1999年 | 3857篇 |
1998年 | 4032篇 |
1997年 | 3722篇 |
1996年 | 3312篇 |
1995年 | 3097篇 |
1994年 | 2906篇 |
1993年 | 2411篇 |
1992年 | 2393篇 |
1991年 | 2222篇 |
1990年 | 2027篇 |
1989年 | 1863篇 |
1988年 | 1730篇 |
1987年 | 1510篇 |
1986年 | 1289篇 |
1985年 | 2469篇 |
1984年 | 2553篇 |
1983年 | 1816篇 |
1982年 | 1915篇 |
1981年 | 1772篇 |
1980年 | 1529篇 |
1979年 | 1294篇 |
1978年 | 981篇 |
1977年 | 936篇 |
1976年 | 831篇 |
1975年 | 537篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的总结26例肾下型腹主动脉瘤的手术治疗经验。方法回顾性分析近5年多来手术治疗26例肾下型腹主动脉瘤的临床资料,全组26例,术前均经影像检查证实诊断。行择期手术21例,破裂型腹主动脉瘤急诊手术5例。26例均行腹主动脉瘤切除,人工血管重建术。结果围手术期死亡2例,均为急症手术患者,总病死率7.7%,急诊手术病死率40.0%。随访时间1-5年。术后1,3,5年生存率分别为96%,88%,75%。死亡原因均与腹主动脉瘤和手术无关。结论CTA检查是诊断腹主动脉瘤的可靠方法。手术治疗仍是治疗腹主动脉瘤的重要方法。瘤体直径不是决定手术的唯一指征。影响手术的危险因素主要是高龄、严重的心肺疾病和肾功能不全。 相似文献
992.
MDR1特异性核酶逆转肝癌多药耐药的实验研究 总被引:2,自引:0,他引:2
目的探讨MDR1核酶(N2A+tRNAi^met-iMDRl-sRz,sRz)在裸鼠体内逆转人肝癌组织多药耐药(MDR)的可行性。方法将原发性MDR人肝癌组织裸鼠原位移植模型第2代随机分为A组(空白对照组:生理盐水40μl+Lipofect AMINE^TM2000 10μ1)、B组(阴性对照组:N2A+tRNAi^met 10μg/40μl+Lipofect AMINE^TM2000 10μl)和C组(核酶组:sRz 10μg/40μl+LipofectAMINE^TM2000 10μl),均开腹瘤内注射。瘤内注药1周后用表阿霉素15mg/kg腹腔注射,每周1次,连续4周。彩色B超测量肿瘤体积。化疗结束后1周处死裸鼠,RT-PCR、Western blot法检测肿瘤中MDR1 mRNA及其蛋白P-gp的表达。结果C组每次化疗后肿瘤体积均较前缩小(F=659.99,P〈0.05)。除第1次化疗外,其余各次化疗后C组的抑制率均高于A、B组(F=35.36,12.77,97.60,P〈0.05)。化疗结束后,C组与瘤源以及A、B组相比,肿瘤组织中MDR1 mRNA和P-gp的表达明显降低(F=45.36,3590.40,P〈0.05)。结论sRz可有效降低肝癌细胞表达MDR1 mRNA和P-gp,一定程度上逆转MDR,提高E-ADM的化疗效果。单纯E-ADM化疗可使肝癌组织MDR1 mRNA和P-gp表达升高,诱导MDR的产生。 相似文献
993.
Alcohol is an important risk factor for human oesophageal cancer. There is evidence from epidemiological studies that some
specific alcoholic drinks, e.g. Calvados apple brandy, are associated with a greater risk than others. Alcohol induces cytochrome
P450 2E1 (CYP2E1) and the hypothesis was tested that different alcoholic beverages, containing a variety of alcoholic compounds,
could differentially induce expression of cytochrome P450 enzymes. Twelve groups of five rats each were treated for 3 days
with different alcoholic beverages (ethanol alone, whisky, farm-produced or commercial Calvados brandy, beer, cider, wine)
adjusted to 4, 10 or 20% of ethanol in drinking water. Immunoblotting using a monoclonal antibody specific for rat CYP2E1
revealed a single protein band in liver microsomes. Densitometric quantitation of microsomal proteins demonstrated a significant
two-, three- and sixfold increase in band intensity after treatment with ethanol concentrations of 4, 10 and 20% respectively,
compared to control rats drinking water alone. There was a dose-dependent increase in liver microsomal metabolism of CYP2E1
substrates (para-nitrophenol and dimethylnitrosamine) in ethanol-treated rats. However, there were no significant differences
in the level of CYP2E1 protein or enzymatic activity between the different alcoholic beverages at the same ethanol concentration.
There was a slight increase in hepatic CYP1A-related enzymatic activities in the alcohol-treated rats compared to the controls,
but no difference between the treated groups either with dose of ethanol or type of beverage. These data show that induction
of CYP2E1 with acute alcohol treatment is predominantly determined by the ethanol content of the beverage.
Received: 10 February 1997 / Accepted: 26 May 1997 相似文献
994.
Fumonisins as a possible contributory risk factor for primary liver cancer: A 3-year study of corn harvested in Haimen, China, by HPLC and ELISA 总被引:13,自引:0,他引:13
Y. Ueno K. Iijima S.-D. Wang Y. Sugiura M. Sekijima T. Tanaka C. Chen S.-Z. Yu 《Food and chemical toxicology》1997,35(12):1143-1150
Employing HPLC fluorometry, gas-liquid chromatography (GLC) and a novel enzymelinked immunosorbent assay (ELISA) based on a monoclonal antibody, 40 corn samples, each collected in 1993 from agricultural stocks for human consumption in Haimen (Jiangsu County) and Penlai (Shandong Province), high- and low-risk areas for primary liver cancer (PLC) in China, respectively, were analysed for fumonisins (FBs), aflatoxins (AFs) and trichothecenes. Levels and positive rates of FBs and deoxynivalenol (DON) were significantly higher in Haimen than in Penlai. ELISA of the 40 corn samples harvested in the two areas in 1994 revealed that FB contamination levels and rates in these areas were comparable to those observed in 1993 in Haimen. ELISA analysis of 1993 and 1994 products revealed a wide occurrence of AFB1 but the positive rates as well as levels were not significantly different between these areas. ELISA of the same sample number of corn harvested in 1995 revealed that FB contamination in Haimen was significantly higher than in Penlai. These 3-yearly surveys of corn samples (240 in total) demonstrated that corn harvested in Haimen was highly contaminated with FBs and that the contamination level, as well as positive rate in 1993 and 1995, were 10–50-fold higher than those in Penlai, suggesting FBs as a risk factor for promotion of PLC in endemic areas, along with the trichothecene DON. Co-contamination with AFs, potent hepatocarcinogens, was assumed to play an important role in the initiation of hepatocarcinogenesis. 相似文献
995.
目的:研究脑缺血后脑片[Ca2+]i变化。方法:采用新型Ca2+荧光指示剂Fura-2双波长法测定兔大脑中动脉阻塞(MCAo)局灶脑缺血后脑片细胞内游离钙([Ca2+]i)。结果:脑缺血后脑组织[Ca2+]i显著升高。结论:[Ca2+]i在脑缺血损害中起重要作用。 相似文献
996.
RAMÓN BATALLER VICENTE ARROYO PERE GINÈS 《Journal of gastroenterology and hepatology》1997,12(11):723-733
Ascites is one of the earliest and most common complications of patients with cirrhosis. A typical circulatory dysfunction characterized by arterial vasodilation, high cardiac output and stimulation of vasoactive systems is commonly present in these patients and is associated with a poor prognosis. The treatment of ascites has been based on the combination of a low-sodium diet and the administration of diuretics. The reintroduction of paracentesis and the recent introduction of the transjugular intrahepatic portosystemic shunt (TIPS) are the most relevant innovations in the treatment of ascites during the past two decades, although controlled trials in large series of patients are needed to delineate whether TIPS is a safe and useful treatment for these patients. 相似文献
997.
Charles Seydoux Danièle Gillard Berguer Eric Eeckhout Frank Stumpe Michel Hurni Patrick Ruchat Hossein Sadeghi Jean-Jacques Goy 《Transplant international》1996,9(4):433-436
Transplant atherosclerotic coronary disease remains the leading cause of death in heart transplant recipients. We report the first case of coronary stent implantation in a heart graft for epicardial focal stenosis. Due to the lower rate of restenosis after stenting in the native coronary artery, we suggest that coronary stenting be considered an acceptable, first intention therapeutic option instead of angioplasty alone whenever possible. 相似文献
998.
Inhaled fentanyl as a method of analgesia 总被引:7,自引:0,他引:7
A study was undertaken to investigate the use of fentanyl by aerosol for postoperative analgesia. Seven patients had placebo, six received fentanyl 100 micrograms and seven were given fentanyl 300 micrograms. A significant improvement in postoperative pain, as assessed by linear visual analogue scale, was achieved in the higher dose group, and in both fentanyl groups the time to alternative analgesia was significantly longer than in the control group. Serum fentanyl levels after inhalation of 100 micrograms reached a plateau around 0.04 ng/ml and after 300 micrograms at around 0.1 ng/ml after 15 minutes. Inhaled fentanyl may have a useful analgesic effect despite these low serum levels; this supports the hypothesis that the mode of analgesia from inhaled opioids may be different from that after other routes of administration. There were no adverse effects such as respiratory depression, bronchospasm, nausea or drowsiness. 相似文献
999.
P. V. Luoma A. Rautio J. Steng»rd E. A. Sotaniemi J. Marniemi 《European journal of clinical pharmacology》1990,38(6):625-627
Summary Serum high density lipoprotein (HDL) subfractions HDL2 and HDL3, apolipoproteins, and plasma antipyrine clearance (AP-CL) rate, an index of liver microsomal enzyme activity, were determined in 21 healthy subjects. High HDL cholesterol and HDL2 cholesterol concentrations and HDL cholesterol/cholesterol and HDL2/HDL3 cholesterol ratios were associated with high AP-CL. Phenobarbital enhanced antipyrine elimination and increased the apolipoprotein A-I/A-II ratio. Subjects who had high AP-CL had a more antiatherogenic HDL subfraction and apolipoprotein profile than those with low AP-CL. 相似文献
1000.
Expression of β-catenin was investigated in normal breast tissue and 66 breast carcinomas in conjunction with expression of epithelial cadherin (E-CD) and α-catenin. In normal mammary ducts and acini, intense β-catenin immunoreactivity was present at the basolateral surfaces of luminal epithelium and weak immunoreactivity was observed at the lateral borders of myoepithelial cells. No β-catenin was revealed at the myoepithelial basal surface. The intercellular expression of β-catenin, as well as of E-CD and α-catenin, was also observed in carcinoma tissues with varying staining intensity. Almost all of 10 intraductal carcinomas and approximately 70% of 41 invasive ductal carcinomas expressed the three molecules at the same level as in normal glands, whereas approximately 80% of 13 invasive lobular carcinomas showed severe deficiency of them. Two lobular carcinomas in situ showed complete absence of all of the proteins. Some of these findings were confirmed biochemically by immunoblotting analysis. In invasive ductal carcinomas, α-catenin was reduced more frequently in diffuse than in solid type tumours, whereas the level of expression of β-catenin and E-CD was unchanged between them. No correlation was present between reduced expression of the adhesion molecules and lymph node metastasis. 相似文献