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   8899篇
  免费   412篇
  国内免费   80篇
耳鼻咽喉   78篇
儿科学   263篇
妇产科学   136篇
基础医学   1089篇
口腔科学   258篇
临床医学   503篇
内科学   2582篇
皮肤病学   186篇
神经病学   666篇
特种医学   481篇
外科学   1441篇
综合类   25篇
预防医学   130篇
眼科学   92篇
药学   450篇
中国医学   19篇
肿瘤学   992篇
  2023年   61篇
  2022年   124篇
  2021年   207篇
  2020年   117篇
  2019年   185篇
  2018年   209篇
  2017年   183篇
  2016年   228篇
  2015年   195篇
  2014年   304篇
  2013年   325篇
  2012年   518篇
  2011年   580篇
  2010年   373篇
  2009年   301篇
  2008年   499篇
  2007年   512篇
  2006年   526篇
  2005年   570篇
  2004年   563篇
  2003年   500篇
  2002年   496篇
  2001年   139篇
  2000年   160篇
  1999年   138篇
  1998年   108篇
  1997年   88篇
  1996年   67篇
  1995年   73篇
  1994年   62篇
  1993年   54篇
  1992年   83篇
  1991年   78篇
  1990年   91篇
  1989年   82篇
  1988年   69篇
  1987年   57篇
  1986年   49篇
  1985年   37篇
  1984年   37篇
  1983年   29篇
  1982年   32篇
  1981年   21篇
  1980年   18篇
  1979年   24篇
  1978年   20篇
  1977年   28篇
  1972年   21篇
  1970年   17篇
  1967年   17篇
排序方式: 共有9391条查询结果,搜索用时 15 毫秒
971.
972.
Filling defects of the left atrial appendage (LAA) on multidetector computed tomography (MDCT) are known to occur, not only due to LAA thrombi formation, but also due to the disturbance of blood flow in the LAA of patients with atrial fibrillation (AF). The purpose of this study was to evaluate the impact of the maintenance of sinus rhythm via ablation on the incidence of LAA filling defects on MDCT in patients with AF. A total of 459 consecutive patients were included in the present study. Prior to ablation, MDCT and transesophageal echocardiography (TEE) were performed. AF ablation was performed in patients without LAA thrombi confirmed on TEE. The LAA filling defects were evaluated on MDCT at 3 months after ablation. LAA filling defects were detected on MDCT in 51 patients (11.1 %), among whom the absence of LAA thrombi was confirmed in 42 patients using TEE. The LAA Doppler velocity in patients with LAA filling defects was lower than that of patients without filling defects (0.61 ± 0.19 vs. 0.47 ± 0.21 m/s; P < 0.0001). The sensitivity, specificity and negative predictive value of MDCT in the detection of thrombi were 100, 91 and 100 %, respectively. No LAA filling defects were observed on MDCT at 3 months after ablation in any of the patients, including the patients in whom filling defects were noted prior to the procedure. MDCT is useful for evaluating the presence of LAA thrombi and the blood flow of the LAA. The catheter ablation of AF not only suppresses AF, but also eliminates LAA filling defect on MDCT suggesting the improvement of LAA blood flow.  相似文献   
973.

Purpose

A small number of lymph nodes retrieved (NLNR) is a known risk factor in stage II colorectal cancer. NLNR is influenced by age, but little is known about whether the impact of small NLNR on survival differs with age. This retrospective study sought to determine such impact in elderly patients with stage II colorectal cancer.

Methods

We reviewed data for 2100 patients with stage II colorectal cancer who underwent surgery without adjuvant chemotherapy between January 1997 and December 2003. The optimal cutoff value of NLNR for survival was determined, and the impact of small NLNR on survival was analyzed. The association between age and NLNR was evaluated. The relation between age and risk of small NLNR with respect to survival was then assessed to determine the impact of small NLNR on elderly patients’ survival.

Results

The optimal cutoff value of NLNR was determined as 6. The small NLNR group (SNG) showed significantly worse prognosis than the large NLNR group (LNG) (p?<?0.001). Age, surgical method, and scope of lymph node dissection were significantly associated with NLNR. A potential interaction was noted between age and risk of small NLNR in relation to relapse-free survival (RFS). Five-year RFS was significantly worse in SNG than in LNG for elderly patients (41.7 and 76.4 %, respectively; p?<?0.001) but not for non-elderly patients (75.9 and 84.6 %, respectively; p?=?0.083).

Conclusions

NLNR <6 was identified to be an important prognostic factor for elderly patients with stage II colorectal cancer.
  相似文献   
974.
Atrioventricular nodal reentrant tachycardia (AVNRT) is a relatively common paroxysmal supraventricular tachycardia. This study investigated whether adenosine-5'-triphosphate (ATP) injection during sinus rhythm might be useful in the noninvasive diagnosis of dual AV nodal pathways. The study group consisted of 9 patients with slow/fast AVNRT and 11 control patients without antegrade dual AV nodal physiology (DAVNP). ATP (2.5 to 30 mg, in 2.5-mg increments was injected during sinus rhythm until signs of DAVNP (> or = 50 msec increase or decrease in AH or PR interval in two consecutive beats) or > or = second-degree AV block was observed. DAVNP was diagnosed by ATP test in all 9 patients with slow/fast AVNRT. DAVNP was observed by ATP test in 3 of the 11 control patients. Thus, the test had a sensitivity of 100% and specificity of 73%. ATP test given during sinus rhythm is useful for identifying patients with dual AV nodal pathways who are prone to AVNRT.  相似文献   
975.
The aim of our study was to examine renal replacement therapies (RRT) that have been used for acute renal failure (ARF) in our intensive care unit (ICU) patients and to compare their outcomes. Sixteen patients who underwent intermittent hemodialysis (IHD), 14 patients who underwent continuous hemofiltration (CHF) in combination with IHD (CHF + IHD), and 38 patients who underwent continuous hemodiafiltration (CHDF) were evaluated. Regarding the effects of blood purification on hemodynamics and renal function, the percentage increase in blood pressure and percent rapid increase in urinary output were the greatest in the CHDF group. The hourly urinary output after the start of initial blood purification increased only in the CHDF group. The survival rate was significantly higher in the CHDF group. These results suggest that CHDF should be the first-line therapy for patients with ARF and that we are moving in the right direction regarding the application of RRT to treat ARF in ICU patients.  相似文献   
976.
We evaluated the usefulness of domestic and foreign guidelines for the diagnosis and treatment of patients with community-acquired-pneumonia at 23 institutions in 6 prefectures of the Tohoku Area, from December 2003 to November 2004. Based on the old and new Japanese Respiratory Society (JRS) guidelines, we evaluated severity, clinical efficacy and detection of atypical pneumonia. As for severity, the old guidelines led to the diagnosis of an excessive number of 'severe' cases. On the other hand, patients were appropriately diagnosed as having mild, moderate, severe, or very severe disease based on the new JRS guidelines (2005). The severity classification often correlated with the Pneumonia Severity Index (PSI) of the IDSA guidelines. The efficacy rate for patients who were prescribed the recommended drug according to the old JRS guidelines was 85.7% and for those who did not use the recommended drug it was 68.7% (p < 0.001).  相似文献   
977.
OBJECTIVE: To evaluate the accuracy of drug susceptibility testing to isoniazid with BACTEC MGIT 960 (MGIT AST) comparing with the standard proportion method using Ogawa medium. METHOD: A total of 1109 M. tuberculosis strains, which were selected from the collection of RYOKEN drug resistance survey in 2002, were selected and subjected to the susceptibility testing to isoniazid using MGIT AST and 1% Ogawa standard methods. The results from MGIT AST were compared with the judicial diagnosis by Ogawa. The sensitivity to detect drug resistance, the specificity for susceptible strain, the efficiency of overall agreement, and kappa coefficient were calculated to evaluate the performance. The treatment process, outcome and prognosis were analysed for the patients on whom the tests showed discrepant results. RESULTS: Compared with the judicial results, the sensitivity, specificity, efficiency, and kappa coefficient of MGIT AST were 100%, 97.1%, 97.3%, and 0.798, respectively. The strains, which showed discrepant results between MGIT AST and Ogawa, were all susceptible by Ogawa and resistant by MGIT AST. A total of 11 out of 30 discrepant cases were followed clinically and no relapse cases were identified, irrespective of the modification of the treatment regimen. As for the proportion of primary INH drug resistance in the present study, it was 5.3% with MGIT AST but was 2.7% with Ogawa, and the difference was statistically significant (p = 0.005). DISCUSSION: The discrepancies on the results of drug susceptibility testing of M. tuberculosis strains to isoniazid between MGIT AST and 1% Ogawa proportion method have been reported. In the present study, the sensitivity, specificity, and overall efficiency of MGIT AST on the prevalent strains in Japan were all beyond 95%, and considered sufficient as the anti-tuberculosis drug susceptibility testing (AST), though 2.7% of discrepancy was observed. Even for the discrepant cases, there was no difference in the treatment outcome and prognosis. Thus, MGIT AST was confirmed as a reliable AST method comparable to Ogawa standard. However, MGIT AST might increase the proportion of INH resistance if it was used as a major AST method, compared with Ogawa.  相似文献   
978.
BACKGROUND: Idiopathic restrictive cardiomyopathy (RCM) is not a single disease and is rare. METHODS AND RESULTS: The clinical features and clinical course of 12 pediatric patients with RCM seen between 1978 and 2005 were retrospectively analyzed. The age at diagnosis ranged from 4 months to 12 years (median 4 years). The age of 7 patients diagnosed because of an abnormal electrocardiogram (ECG) ranged from 4 to 12 years. Three infants less than 2 years old presented with cardiomegaly. Obliquely elevated ST-T segments and the late peak T waves on 12-lead ECG were present in 8 patients (67%). Three patients with ST depression during exercise had no perfusion defects on radioisotope myocardial perfusion imaging. Two patients underwent orthotopic heart transplantation. Of the remaining 10 patients, 7 have died: 4 died suddenly and 3 died of right heart failure. Three patients with a hypertrophic left ventricular wall had a prolonged survival. The probability of survival at 1, 2 and 3 years was 78%, 52% and 26%, respectively. CONCLUSIONS: Obliquely elevated ST-T segments and the late peak T wave on ECG are characteristic, and reflect the restrictive physiology, which may indicate abnormalities of repolarization of ventricular muscle. The mode of death was either heart failure from pulmonary hypertension or sudden death from presumed ventricular arrhythmia.  相似文献   
979.
The relationship between the renin–angiotensin aldosterone system and short-term blood pressure variability has not been well elucidated. Here, we investigated whether blood pressure variability determined by ambulatory blood pressure monitoring differed among patients with primary aldosteronism (PA), renovascular hypertension (RVHT), and essential hypertension (EHT). We examined 25 patients with PA, 28 patients with RVHT, and 18 patients with EHT. Ambulatory blood pressure monitoring was conducted in all patients. Short-term blood pressure variability was evaluated by calculating the standard deviation (SD), coefficient of variation (CV), and average real variability (ARV) of 24-h, daytime, and nighttime blood pressure values. Day–night differences in blood pressure were also determined. The mean 24-h systolic blood pressure (SBP) and the mean diastolic blood pressure (DBP) in the PA and RVHT groups were found to be comparable to those in the EHT group. The SD, the CV, nor the ARV of the 24-h, daytime, and nighttime blood pressures showed any significant differences among the three groups. The day–night differences in blood pressure were comparable among the three groups. The short-term blood pressure variabilities evaluated by ambulatory blood pressure monitoring were comparable among the patients with EHT, RVHT, and PA. The results suggest that the renin–angiotensin aldosterone system may contribute little to short-term blood pressure variability in individuals with hypertension.  相似文献   
980.
The patient was a 43-year-old woman with obesity (body mass index: 29.1) and glucose intolerance who was not taking oral contraceptives. An ultrasound showed a hypoechoic hepatic mass. Dynamic contrast-enhanced computed tomography revealed a lesion in segment 6 that showed homogeneous and slight-to-moderate enhancement in the arterial phase with persistent enhancement during the portal and equilibrium phases. On magnetic resonance (MR) imaging, the lesion demonstrated hyperintensity on T2- and diffusion-weighted images and hypointensity in the hepatobiliary phase of gadoxetic-acid-enhanced MR imaging. In addition to the main lesion, approximately ten small hypointense lesions were seen in the hepatobiliary phase. The background liver was fatty without the deformity of chronic liver disease. Based on the pathological findings of the main lesion biopsy, it was initially suspected to be a non-neoplastic lesion with hematoxylin and eosin staining and initial immunohistochemical staining. However, the radiological findings indicated a neoplastic lesion. Additional immunohistochemical staining, including that for α-smooth muscle actin and organic anion transporter polypeptide 1B3, in combination with the radiological findings resulted in a diagnosis of unclassified hepatocellular adenoma. The other small lesions were presumed to be related to the main lesion.  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