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   44669篇
  免费   2103篇
  国内免费   376篇
耳鼻咽喉   445篇
儿科学   990篇
妇产科学   496篇
基础医学   5977篇
口腔科学   770篇
临床医学   2699篇
内科学   11490篇
皮肤病学   1023篇
神经病学   3330篇
特种医学   1822篇
外科学   7761篇
综合类   184篇
一般理论   6篇
预防医学   1169篇
眼科学   1008篇
药学   2745篇
中国医学   170篇
肿瘤学   5063篇
  2023年   245篇
  2022年   507篇
  2021年   900篇
  2020年   473篇
  2019年   663篇
  2018年   924篇
  2017年   703篇
  2016年   894篇
  2015年   980篇
  2014年   1268篇
  2013年   1608篇
  2012年   2602篇
  2011年   2892篇
  2010年   1653篇
  2009年   1512篇
  2008年   2738篇
  2007年   2953篇
  2006年   2970篇
  2005年   2981篇
  2004年   3085篇
  2003年   3138篇
  2002年   3092篇
  2001年   502篇
  2000年   427篇
  1999年   570篇
  1998年   773篇
  1997年   645篇
  1996年   604篇
  1995年   506篇
  1994年   456篇
  1993年   490篇
  1992年   318篇
  1991年   312篇
  1990年   261篇
  1989年   249篇
  1988年   253篇
  1987年   188篇
  1986年   169篇
  1985年   158篇
  1984年   172篇
  1983年   128篇
  1982年   129篇
  1981年   156篇
  1980年   131篇
  1979年   98篇
  1978年   105篇
  1977年   82篇
  1976年   66篇
  1975年   56篇
  1974年   45篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
In a 43-year-old Japanese Brazilian who came to Japan in 2001, since subjective symptoms such as cough, sputum, and dyspnea on exertion had become severe, he was referred to our hospital because of suspicion of pulmonary tuberculosis in chest radiography and CT findings. A chest radiograph of initial examination showed interstitial shadows in both lungs with nodular, infiltrative or cavitary changes. No Mycobacterium tuberculosis was found. The mycetocyte with multipolar budding resembling the steerage of a ship, which was characteristic of Paracoccidioides was observed in sputum and transbronchial lung biopsy specimens. We cultured a fungus to show dimorphism of temperature dependency, and a diagnosis of chronic lung paracoccidioidomycosis was arrived at. By administration of ITCZ 200 mg/day, the chest radiography findings and clinical manifestations were improved. This case seems to be worthy of reporting in Japan since the affected site or organ was limited to the two lungs with multiple cavitary lesions and fibrotic changes on radiographic examination, and final diagnosis was made by cytology of sputum and pathology of TBLB specimens.  相似文献   
992.
OBJECTIVES: This study evaluated the sensitivity and the related factors in iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) scintigraphy to detect stable angina. METHODS: The subjects were 198 patients with stable angina who underwent BMIPP before percutaneous coronary intervention or coronary bypass graft surgery. Patients with unstable angina, myocardial infarction, congestive heart failure, cardiomyopathy and vasospastic angina were excluded. After investigation of the sensitivity of BMIPP, the patients with single-vessel disease without collateral flow were classified into the normal (123)I-BMIPP uptake group (normal group)or decreased (123)I-BMIPP uptake group (decreased group), and various factors were compared between the two groups. RESULTS: Sensitivity was 61% overall, 58% in single-vessel disease, 69% in double-vessel disease, 53% in triple-vessel disease, 43% in only left main vessel disease, and 89% in left main and other vessel disease (NS). In single-vessel disease, the sensitivity was 40% in 75% coronary artery stenosis, 58% in 90% stenosis, 89% in 99% stenosis, and 69% in total occlusion (p = 0.003). Comparing the deoreased and normal groups, diabetes mellitus was more frequent in the normal group (14.6% vs 39.5%), minimal lumen diameter was smaller (0.75 +/- 0.37 vs 0.98 +/- 0.49 mm) and lesion length was longer in the decreased group (15.4 +/- 4.9 vs 11.6 +/- 5.5 mm). Logistic multivariate analysis showed that the independent factors were diabetes mellitus [odds ratio 0.20, 95% confidence interval (CI) 0.04-0.87, p = 0.03], minimal lumen diameter (odds ratio 0.10, 95% CI 0.02-0.48, p = 0.003) and lesion length (odds ratio 1.12, 95% CI 1.00-1.25, p = 0.03). CONCLUSIONS: BMIPP is useful in stable angina patients because of the acceptable sensitivity. Diabetes mellitus, minimal lumen diameter and lesion length were independent factors associated with decreased BMIPP uptake.  相似文献   
993.
BACKGROUND: It has been reported that recording electrocardiograms (ECGs) in the 3rd intercostal space (ICS) is one method that can be used for detecting Brugada syndrome; however, the prevalence of Brugada-type ECGs recorded in the 3rd ICS and the usefulness of recording the ECG in the 3rd ICS in accordance with recently established electrocardiographic criteria is unknown. METHODS AND RESULTS: ECGs were recorded in both the 4th and 3rd ICS in 17 Brugada-type ECG patients (group A) and in 206 consecutive male subjects (group B). Brugada-type ECGs were divided into 3 types. In group A, the prevalence of type 1 ECG, which is a coved-type ECG with ST-segment elevation of >/=2 mm, increased from 23.5% to 64.7% when ECG was recorded in the 3rd ICS. The conversion to type 1 ECG was found to be related to induction of ventricular arrhythmia. In group B, the prevalence of Brugada-type ECG increased from 1.5% to 5.8% when the ECG was recorded in the 3rd ICS. CONCLUSIONS: Recording the ECG in the 3rd ICS is useful for identifying high-risk patients with Brugada-type ECG and for detecting concealed Brugada-type ECG.  相似文献   
994.
BACKGROUND: There are few reports regarding the concordance of coronary arterial response between acetylcholine (ACh) and ergonovine (ER) spasm provocation tests. OBJECTIVES: We attempted to perform selective spasm provocation tests to examine the incidence of provoked spasm in patients who had undergone first coronary angiography as much as possible and we compared the coronary arterial response and clinical usefulness between selective intracoronary injection of ACh and intracoronary administration of ER. METHODS: We performed 1508 selective spasm provocation tests, consisting of 873 ACh tests and 635 ER tests, from 1991 to 2002. We examined the frequency of provoked spasms of each agent retrospectively. ACh was injected in incremental doses of 20, 50 and 80 microg into the right coronary artery and 20, 50 and 100 microg into the left coronary artery. ER was administered as 10 microg/min over 4 min for a maximal dose of 40 microg in the right coronary artery and as 16 microg/min over 4 min for a total dose of 64 microg in the left coronary artery. Coronary spasm was defined as transient >99% luminal narrowing. RESULTS: Intracoronary ACh provoked spasms in 36.0% of patients and intracoronary ER induced spasms in 29.8% of patients. In patients with ischemic heart disease, the incidence of provoked spasms was not different between ACh tests (50.9%) and ER tests (43.8%). In contrast, the frequency of provoked spasms with ACh tests was significantly higher than that with ER tests (11.0% compared with 6.4%, P<0.05) in patients without ischemic heart disease. Moreover, ACh provoked more spasms in patients without fixed stenosis than ER (36.2% compared with 25.5%, P<0.01) and multiple spasms were frequently observed when performing ACh tests (40.0% compared with 27.0%, P<0.01). Major complications were observed in 1.4% of patients with ACh tests and in 0.2% of patients with ER tests. The need for intracoronary administration of isosorbide dinitrate to relieve coronary spasms during ER testing before performing another coronary artery test was more frequently observed in ACh tests (5.04% compared with 1.49%, P<0.01). However, no serious irreversible complications, such as death or acute myocardial infarction, were observed in this study. There was a significant difference in sex, history of smoking and hyperlipidemia between patients with and without spasms for both tests, whereas no difference in age or hypertension was observed in either test. CONCLUSION: Thus, both selective ACh and ER tests were useful as spasm provocation tests.  相似文献   
995.
A case of solitary neurofibroma in the retroperitoneum involving the uncinate process of the pancreas, which has been reported in only one case in Japan and less than 20 cases in the world literature, is described. A 57-year-old male complained of back pain and microhematuria. Plain and enhanced abdominal computed tomography (CT) indicated an 8 × 6 cm hypovasular tumor located in the uncinate process. We initially assumed it to be a cancer of the pancreas. His physical examination and blood chemistry result were normal. Various diagnostic imaging methods however, disclosed a rare type of tumor. The tumor was resected by pancreaticoduodenectomy and histological examination revealed it to be neurofibroma.  相似文献   
996.
BACKGROUND: Heart failure consists of two phenotypes: systolic heart failure and diastolic heart failure (DHF). A growing body of evidence demonstrated benefits of beta-blocker, angiotensin-converting enzyme inhibitor, and angiotensin II receptor blocker in systolic heart failure; however, evidence leading to therapeutic strategy of DHF is lacking. METHODS AND RESULTS: The Japanese Diastolic Heart Failure Study (J-DHF) is a multicenter, prospective, randomized trial designed to assess effects of beta-blocker in patients with DHF. A total of 800 patients (400 patients in each group) will be enrolled. The primary outcome is a composite of cardiovascular death and unplanned admission to hospital for congestive heart failure. Other outcomes include all-cause mortality, worsening of the symptoms of heart failure, or a need for modification of the treatment for heart failure. Serial assessment of echocardiographic and neurohumoral parameters and cost analysis of the treatment regimen will be conducted. The follow-up period is a minimum of 2 years. CONCLUSION: This study will provide important evidences for the treatment of DHF.  相似文献   
997.
998.
BACKGROUND: GIK-201Tl imaging reportedly improves the detection of viable myocardium, so the present study evaluated whether it can detect myocardial viability after acute myocardial infarction (AMI). METHODS AND RESULTS: Resting 201Tl and 99mTc-pyrophosphate (PYP) dual single photon emission computed tomography (SPECT) and 201Tl SPECT after 201Tl with GIK (10% glucose, insulin 5 U, and KCl 10 mmol) infusion (GIK-201Tl) were performed in 25 AMI patients within 10 days of admission. GIK-201Tl SPECT images were obtained immediately and 4 h after infusion. Left ventriculography (LVG) was performed within 3 weeks and at 6 months when follow-up 201Tl SPECT was also performed. From 20 SPECT segments, both the summed defect score (RDS) and the number of defect segments (ES) were calculated. The infarcted area was defined as 99mTc-PYP uptake segments. Wall motion was estimated in 7 LVG segments. The ES of R-201Tl (5.5 +/- 2.8), immediate GIK-201Tl (4.0 +/- 2.3), and 4-h GIK-201Tl (5.6 +/- 2.7) were lower than that of 99mTc-PYP (7.5 +/- 4.1) (p<0.05), and the ES had significantly declined 6 months later on 201Tl (3.5 +/- 2.8) (p<0.05). Although the RDS of R-201Tl (11.3 +/- 7.9) and 4-h GIK-201Tl (11.2 +/- 6.3) were greater than at the 6-month 201Tl (7.1 +/- 6.5), immediate GIK-201Tl (7.4 +/- 6.5) was equivalent to follow-up 201Tl. The sensitivity of immediate GIK-201Tl was highest among the imaging methods. CONCLUSION: To detect myocardial viability after AMI, early imaging with GIK-201Tl is more useful than resting 201Tl imaging.  相似文献   
999.
1000.
CD8+ cytotoxic T-lymphocytes are major effector cells involved in immunologically specific tumor destruction in vivo, and CD4+ T-cells are essential for controlling this CD8+ T-cell-dependent tumor eradication. The presence of CD4+ T-cells with distinct functional roles has been recognized. The further understanding of the complexity of antitumor immune responses by CD4+ T-cells may be crucial for designing more effective cancer vaccines.  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