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   24079篇
  免费   1667篇
  国内免费   357篇
耳鼻咽喉   464篇
儿科学   341篇
妇产科学   287篇
基础医学   3671篇
口腔科学   461篇
临床医学   1843篇
内科学   4871篇
皮肤病学   1051篇
神经病学   1681篇
特种医学   1324篇
外国民族医学   3篇
外科学   3517篇
综合类   413篇
一般理论   11篇
预防医学   952篇
眼科学   762篇
药学   2038篇
  3篇
中国医学   369篇
肿瘤学   2041篇
  2024年   30篇
  2023年   198篇
  2022年   577篇
  2021年   854篇
  2020年   479篇
  2019年   637篇
  2018年   771篇
  2017年   631篇
  2016年   877篇
  2015年   1209篇
  2014年   1442篇
  2013年   1488篇
  2012年   2314篇
  2011年   2141篇
  2010年   1290篇
  2009年   1113篇
  2008年   1444篇
  2007年   1323篇
  2006年   1169篇
  2005年   1137篇
  2004年   919篇
  2003年   729篇
  2002年   716篇
  2001年   402篇
  2000年   340篇
  1999年   286篇
  1998年   145篇
  1997年   120篇
  1996年   83篇
  1995年   84篇
  1994年   76篇
  1993年   48篇
  1992年   119篇
  1991年   108篇
  1990年   92篇
  1989年   104篇
  1988年   102篇
  1987年   78篇
  1986年   67篇
  1985年   56篇
  1984年   51篇
  1983年   55篇
  1982年   14篇
  1981年   24篇
  1980年   13篇
  1979年   35篇
  1978年   14篇
  1977年   21篇
  1976年   10篇
  1974年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
He R  Sang H  Ye RD 《Blood》2003,101(4):1572-1581
  相似文献   
982.
Koh YY  Kang EK  Kang H  Yoo Y  Park Y  Kim CK 《Chest》2003,124(3):819-825
BACKGROUND: The mechanisms responsible for bronchial hyperresponsiveness (BHR) in symptomatic asthma include genetic predisposition and airway inflammation, but the causes of BHR in adolescents with asthma remission are poorly understood. It has been shown that BHR in adolescents with asthma remission was not reduced by prolonged treatment with inhaled corticosteroids, in contrast to the BHR of symptomatic asthma. OBJECTIVE: The aim of this study was to investigate whether family history of BHR may contribute to the persistence of BHR in asthma remission during adolescence. METHODS: One hundred twenty-six adolescents with long-term asthma remission (neither symptoms nor any medication used during the previous 2 years) and their parents underwent a methacholine inhalation test. The provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)) and the bronchial responsiveness (BR) index were calculated for each individual. RESULTS: Sixty-nine adolescents (54.8%) were found to have persisting BHR (PC(20) < 18 mg/mL). The frequency of BHR and the BR index were significantly higher in parents (n = 138) of the BHR-persisting group (28.3% and 1.150 +/- 0.103, respectively [mean +/- 1 SD]) than in parents (n = 114) of BHR-nonpersisting group (16.7% [p = 0.030] and 1.124 +/- 0.088 [p = 0.029], respectively). Furthermore, adolescents (n = 56) with at least one BHR-positive parent were found to have a higher frequency of BHR (66.1% vs 45.7%, p = 0.023) and a higher BR index (1.244 +/- 0.090 vs 1.204 +/- 0.082, p = 0.011) than adolescents (n = 70) with non-BHR parents. CONCLUSION: Our results suggest that adolescents in asthma remission are more likely to have BHR when there is a family history of BHR. Further studies are needed to examine the possible involvement of genetic factors in the BHR of adolescents in asthma remission.  相似文献   
983.
BACKGROUND & AIMS: We examined the use of both covered and uncovered Wallstents in patients with malignant extrahepatic biliary obstruction to determine whether use of covered Wallstents prolonged stent patency without increasing procedure-related complications. METHODS: Commercially available silicone-covered Wallstents were prospectively evaluated in 98 patients who underwent insertion from December 2002-December 2004. Those data were compared with data obtained by retrospectively studying 108 consecutive patients who underwent endoscopic insertion of uncovered Wallstents between January 2000-November 2002, and for whom accurate and complete follow-up details were available. RESULTS: The mean stent patency was similar for both groups, 148.9 days (range, 3-667 days) for covered Wallstents and 143.5 days (3-910 days) for uncovered Wallstents (P = .531). The 2 groups also did not significantly differ in terms of cumulative stent patency according to the Kaplan-Meier lifetime table. The incidence of mild pancreatitis was similar in both groups, occurring in 6 patients with covered stents (6/98, 6.1%) and 2 patients with uncovered stents (2/108, 1.9%) (P = .154). Excluding those patients who had previously undergone cholecystectomy, acute cholecystitis occurred in 5 of 88 patients with covered Wallstents (6.1%) and 1 of 100 patients with uncovered stents (1%) (P = .104). Stent migration occurred in 6 patients with covered stents (6.1%) and 0 patients with uncovered stents (P = .011). CONCLUSION: Covered Wallstents might not prolong stent patency compared with uncovered Wallstents when used in the management of malignant extrahepatic biliary obstruction.  相似文献   
984.
Hepatocellular carcinoma (HCC) is one of the most common malignant neoplasms occurring worldwide. Surgical resection currently provides the best chance of long-term tumor free survival, but the most HCCs are not candidates for surgical excision due to poor liver function or poor medical background. Numerous noninvasive alternatives to surgical resection have been introduced to treat liver cancers. Radiofrequency thermal ablation has begun to receive much attention as an effective and minimally invasive technique for the local control of HCC. The biliary system related complications after radiofrequency ablation has rarely been reported. We report a case of biliary-duodenal fistula with liver abscess after radiofrequency ablation for HCC. The case was treated by abscess drainage and antibiotics.  相似文献   
985.
BACKGROUND/AIMS: Helicobacter pylori (H. pylori) is an important cause of various gastrointestinal diseases. H. pylori eradication is essential for the cure and prevention of associated diseases. Nowdays, proton pump inhibitor (PPI)-based triple therapy is the standard eradication regimen. The aims of this study were to compare the H. pylori eradication rate of different PPI-based triple therapies and to find out the factors influencing the eradication rate. METHODS: From May 2002 through February 2004, H. pylori infected patients were treated with the eradication regimen based on one of the four PPIs (omeprazole, rabeprazole, esomeprazole and lansoprazole) for 1 or 2 weeks. After two weeks, drug compliance, adverse effects, and smoking history during the eradication therapy were obtained. The follow-up H. pylori test was performed 4 weeks after the completion of therapy. The data were analyzed by Chi-square test and multiple logistic regression analysis. RESULTS: Overall eradication rate was 83.5%. There was no significant difference in eradication rate among four PPIs (p=0.379). Odds ratio (OR) for omeprazole and rabeprazole was 1.15 (95% CI 0.50-2.68); for omeprazole and esomeprazole, OR 1.63 (95% CI 0.68-3.89); and for omeprazole and lansoprazole, OR 1.13 (95% CI 0.50-2.56). Smoking habit, site of ulcer, and the duration of therapy affected the eradication rate significantly. CONCLUSIONS: The efficacy of four different PPIs for H. pylori eradication is similar to each other. Smoking, site of ulcer, and the duration of treatment have significant effects on eradication rates.  相似文献   
986.
BACKGROUND/AIMS: Although previous reports suggested that pepsinogen (PG) I/II ratio was the index of gastric atrophy, PG I/II ratio was also related to other factors such as Helicobacter pylori (H. pylori) infection, various gastrointestinal diseases, and aging. The aim of this study was to evaluate the relationship between serum PG I/II ratio and age or upper gastro-intestinal diseases according to H. pylori infection status. METHODS: A total of 529 individuals (307 male; mean age, 57.2 years) were divided into 4 groups (94 gastric ulcers, 35 duodenal ulcers, 105 reflux esophagitis, and 295 atrophic gastritis) according to endoscopic diagnosis. H. pylori infection was determined by H. pylori IgG antibody (ELISA) and PG was measured by latex immunoassay. RESULTS: H. pylori infected patients showed markedly increased serum PG II levels (24.0+/-14.7 ng/mL vs. 13.8+/-16.6 ng/mL, p0.001) and low PG I/II ratio (3.9+/-2.0 vs. 6.0+/-2.5, p0.001) than non-infected subjects. In H. pylori infected patients, mean PG I/II ratios in the gastric ulcer and atrophic gastritis group were significantly lower than those of the duodenal ulcer and reflux esophagitis group (p0.001, ANOVA, Turkey's multiples comparison test). The mean ratio of open type atrophic gastritis was lower than that of close type atrophic gastritis (3.0+/-1.4 vs. 3.8+/-1.7, p0.005). PG I/II ratio gradually decreased with age in H. pylori-infected patients with atrophic gastritis (R(2)=0.9, p=0.005, linear regression analysis). CONCLUSION: Serum PG I/II ratio reflects H. pylori infection and gastric atrophy. In the presence of H. pylori infection, gastric atrophy progresses with age.  相似文献   
987.
BACKGROUND: Cilostazol, a phosphodiesterase inhibitor, is an antiplatelet agent with positive chronotropic effect, the impact of which on left ventricular (LV) volume and function in acute myocardial infarction (AMI) was evaluated in the present study. METHODS AND RESULTS: In 56 patients with AMI treated with primary coronary stenting, serial echocardiographic studies within 24 h and at 6 months were performed. Patients received a conventional antiplatelet regimen either without cilostazol (group 1, n=29) or with cilostazol (group 2, n=27). At 6 months, the difference in the change in heart rate between group 1 and group 2 was statistically significant (9.9 beats/min; p=0.04). However, changes in LV end-systolic volume (LVESV) (7.1+/-8.2 vs 10.0+/-21.7 ml, p=0.60), LV ejection fraction (EF) (8.2+/-9.9 vs 9.0+/-12.6%, p=0.85) and the ratio of early mitral inflow velocity to the mitral annular velocity (E/E') (0.6+/-3.7 vs -1.7+/-3.2) were not different between the 2 groups. Cardiac event rate was similar between the 2 groups. On multivariate regression analyses, cilostazol therapy had no significant influence on the changes in LVESV, LVEF or E/E'. CONCLUSIONS: In this study, the addition of cilostazol on conventional drug therapy had no adverse influence on LV remodeling or LV function after AMI.  相似文献   
988.
BACKGROUND/AIMS: MELD-Na (model for end-stage liver disease with incorporation of serum sodium) was suggested to provide better survival prediction than MELD alone for patients with end stage liver disease. However, there is no data verifying the usefulness of MELD-Na for predicting short term mortality of cirrhotic patients in Korea. This study was aimed to determine whether MELD-Na would be more accurate in predicting short term mortality than other scoring systems such as Child-Turcotte-Pugh (CTP) or MELD. METHODS: Data from 355 patients admitted due to liver cirrhosis were retrospectively reviewed. The cumulative survival rates were obtained. Prediction of mortality rate for three months and one year were analyzed using the area under the receiver's operating characteristics curve (AUC). RESULTS: One hundred patients (28%) died during the study period. All of the three systems showed significant differences in the cumulative survival rate according to the scores on admission (p0.001). The AUC of CTP, MELD, and MELD-Na in predicting three-months mortality were 0.828, 0.845, and 0.862 (p0.05), and the AUC of each score system for death within one year were 0.792, 0.800, and 0.831, respectively (p0.05). The AUC of MELD-Na in predicting short term death were the highest, although it was not statistically significant. Multivariate analysis showed that only MELD-Na was significantly related to three-month mortality (p=0.012). CONCLUSIONS: MELD-Na is more appropriate in predicting short term mortality, but larger scale studies are needed to confirm the superiority of MELD-Na to MELD and CTP in patients with liver cirrhosis.  相似文献   
989.
A 70-year-old woman presented with headaches and recurrent stroke symptoms. During five years, the patient has been treated for cerebral infarction associated with severe atherosclerotic stenosis of the internal carotid artery. Three-year follow-up magnetic resonance angiography showed a tiny de novo aneurysm arising from the distal part of atherosclerotic internal carotid artery. And 5-year follow-up three-dimensional CT angiogram demonstrated a definite aneurysm enlargement as large as requiring treatment. During dissection of aneurysm, the oculomotor nerve was found to be penetrated with the growing de novo aneurysm. The authors report a case of a de novo aneurysm, which resulted from atherosclerotic stenosis of the internal carotid artery at the supraclinoid portion, that was found to be penetrating the oculomotor nerve with no ocular palsy.  相似文献   
990.
Weakness of the dorsiflexor muscles of the ankle or toe, referred to as foot drop, is a relatively common presentation. In most cases, foot drop is caused by a lower motor neuron disease such as peroneal peripheral neuropathy, L4-5 radiculopathic sciatic neuropathy, or polyneuropathy. Although upper motor neuron lesions can present as foot drop, the incidence is very rare. Here, we report an extremely rare case in which foot drop was the only presenting symptom of cerebral infarction.  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