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   17362篇
  免费   901篇
  国内免费   110篇
耳鼻咽喉   256篇
儿科学   299篇
妇产科学   141篇
基础医学   2371篇
口腔科学   328篇
临床医学   1155篇
内科学   4308篇
皮肤病学   247篇
神经病学   1279篇
特种医学   629篇
外科学   3169篇
综合类   74篇
一般理论   1篇
预防医学   619篇
眼科学   278篇
药学   1063篇
中国医学   25篇
肿瘤学   2131篇
  2023年   99篇
  2022年   67篇
  2021年   346篇
  2020年   172篇
  2019年   265篇
  2018年   360篇
  2017年   268篇
  2016年   371篇
  2015年   378篇
  2014年   465篇
  2013年   533篇
  2012年   891篇
  2011年   979篇
  2010年   558篇
  2009年   511篇
  2008年   832篇
  2007年   901篇
  2006年   923篇
  2005年   881篇
  2004年   860篇
  2003年   832篇
  2002年   783篇
  2001年   527篇
  2000年   535篇
  1999年   462篇
  1998年   265篇
  1997年   174篇
  1996年   197篇
  1995年   171篇
  1994年   151篇
  1993年   135篇
  1992年   336篇
  1991年   265篇
  1990年   288篇
  1989年   268篇
  1988年   239篇
  1987年   202篇
  1986年   220篇
  1985年   208篇
  1984年   163篇
  1983年   133篇
  1982年   74篇
  1980年   73篇
  1979年   144篇
  1978年   89篇
  1977年   80篇
  1975年   65篇
  1974年   66篇
  1971年   61篇
  1969年   60篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Acute pulmonary thromboembolism is a frequently lethal and acute-onset in-hospital complication after surgery. Absolute indications for surgical embolectomy are acute massive pulmonary embolism with deep shock, refractory circulatory collapse, and continuous hypoxemia. Although thrombolytic therapy is indicated for patients with pulmonary thromboembolism with right ventricular overload, it is contraindicated for patients after major surgery or with stroke due to the high risk of rebleeding. Therefore surgical embolectomy should be considered in those patients. Pulmonary embolectomy relieves the right ventricular overload, and immediate restoration of right ventricular function contributes to the recovery of hemodynamics. A recent study revealed improved outcome for massive pulmonary embolism with early diagnosis with multidetector-row computed tomography, risk stratification using echocardiography, and surgical embolectomy. Surgical pulmonary thromboembolectomy should be considered for critically ill patients with massive pulmonary thromboembolism.  相似文献   
992.
993.
Idiopathic portal hypertension (IPH) requires invasive measures to prevent rupture and bleeding of esophagogastric varices. However, the long-term results of shunt surgery for IPH have not been reported. In particular, the pros and cons of surgery that preserves the spleen and its long-term hematologic effects have not been described. The records of 15 patients who underwent distal splenorenal shunt with splenopancreatic and gastric disconnection (DSRS with SPGD) for IPH between 1983 and 1998 was reviewed retrospectively. One patient died within 3 years of surgery, for a 3-year survival rate of 93%; the 10-year survival rate was 64%. Three patients (18%) suffered rebleeding from esophagogastric varices. The white blood cell and platelet counts were higher 3–5 years and 7–13 years postoperatively compared with preoperative values. Four of five patients who underwent postoperative computed tomography had a smaller spleen postoperatively. DSRS with SPGD provides long-term hemostasis for esophagogastric variceal bleeding in IPH and alleviates hypersplenism. DSRS with SPGD is an effective treatment for patients with IPH in whom long-term survival is expected.  相似文献   
994.
Bacterial translocation sometimes occurs in patients during surgical stress and is associated with an increased incidence of septic morbidity. However, no reliable method has been established for diagnosing bacterial translocation in humans. Identification of minute quantities of microbial-specific DNA has been made possible using polymerase chain reaction (PCR) techniques. The aims of this study were to determine the prevalence of bacterial translocation in patients with surgical stress using PCR techniques and to evaluate the usefulness of blood PCR techniques for diagnosing bacterial translocation. DNA was extracted from the blood of 52 surgical patients (24 elective major surgery patients and 28 septic patients) and 10 healthy controls. PCR techniques were used to amplify genes from Escherichia coli, Bacteroides fragilis, a region of 16S ribosomal RNA found in many gram-positive and gram-negative bacteria, and Candida albicans. Bacterial and Candida albicans DNA were not detected in healthy volunteers. Enteric bacterial DNA was detected in patients with hepatic lobectomy, and Candida albicans DNA was detected in patients with esophagectomy on the first postoperative day. Enteric bacterial and Candida albicans DNA were detected in septic patients with findings diagnostic of bacterial translocation, such as small bowel obstruction, ulcerative colitis, or supramesenteric arterial occlusion or in those who had undergone chemotherapy for advanced colon cancer. However, none of the patients were positive by the blood culture technique. The PCR method is more sensitive than blood cultures for detecting bacterial components in the blood of septic patients and is a valuable tool for verifying bacterial translocation in patients who have undergone hepatic lobectomy or esophagectomy. It is also valuable in septic patients who do not have a defined focus of infection.  相似文献   
995.
Apoptosis in the supraspinatus tendon with stage II subacromial impingement   总被引:3,自引:0,他引:3  
The purpose of this study was to investigate the histopathology, including apoptosis, in the supraspinatus tendon with stage II subacromial impingement. Samples from the critical zone of the supraspinatus tendon were obtained from 5 patients with subacromial impingement syndrome and 10 autopsy cases without shoulder diseases as controls. Three-micrometer-thick sections were cut and stained with hematoxylin-eosin (H-E) for routine histologic examination. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method and single-stranded deoxyribonucleic acid (ssDNA) assay in which the frequency of the apoptotic cells was expressed by the apoptotic index. Control supraspinatus tendons showed normal morphology, whereas supraspinatus tendons from shoulders with impingement showed significant mucoid degeneration. Correspondingly, few apoptotic cells were observed in control tendons, whereas a large number of apoptotic cells were observed in the degenerative area of tendons from impingement shoulders. The apoptotic indices were significantly higher in the impingement shoulders (ssDNA, 18.84% +/- 1.75%; TUNEL, 24.92% +/- 2.79%) than in the control shoulders (ssDNA, 5.22% +/- 1.30%; TUNEL, 7.01% +/- 1.05%) (P = .04 for ssDNA and P = .017 for TUNEL). Mechanical impingement seems to cause tendon degeneration and apoptosis of the tendon cells in the supraspinatus tendon in stage II impingement.  相似文献   
996.
997.
Free vascularized fibula transfer is an established method for reconstruction of the wrist following tumor resection. In cases of resection of the radial articular surface, three reconstructive options are possible: fibular head transfer along with the shaft to replace the radial joint surface, fixation of the fibula to the scaphoid and lunate, or a complete wrist fusion. Three patients with a tumor involving the distal end of the radius were treated with wide resection, and subsequent wrist reconstruction was performed, using the above-mentioned procedures. Although our experience included only a small number of patients, both radio-carpal hemiarthroplasty and fibulo-scapho-lunate fusion similarly provided successful wrist stability and functional range of motion in these cases. Even when the wrist was totally fused with the fibula, its function was still acceptable.  相似文献   
998.
PURPOSE: We investigated the prognostic impact of lymphovascular invasion (LVI) and traditional prognostic factors for survival in a large series of patients treated surgically for upper tract transitional cell carcinoma (TCC). We also developed a prognostic factors-based model for risk stratification of upper tract TCC. MATERIALS AND METHODS: We identified a study population of 173 consecutive patients treated surgically for upper tract TCC at our institution between 1980 and 2002. We compared LVI with other pathological features and determined the disease specific survival rate. RESULTS: LVI was found in 52 patients (30.1%). As tumor grade and pathological stage increased, the incidence of LVI increased significantly. LVI was found in 12 of 133 patients (9.0%) without lymph node metastasis compared with 40 of 40 patients (100%) with lymph node metastasis. Five and 10-year disease specific survival rates were 84.9% and 80.4% in the absence of LVI, and 40.2% and 21.1% in the presence of LVI, respectively (p <0.001). In multivariate analysis LVI, pathological T stage and tumor grade were independent predictors for disease specific survival. The relative risk of death could be expressed with the formula, exp(0.729 x tumor grade + 1.659 x pathological T stage + 1.160 x LVI). Using this equation the patients were stratified into low risk (grade 1 or 2, LVI negative, stage pT2 or lower), high risk (any tumor grade, LVI positive, stage pT3 or greater) and intermediate risk (all others) groups with significant differences in survival. Five and 10-year disease specific survival rates were 93.0% and 89.4% in the low risk group (82 patients), 66.8% and 62.9% in the intermediate risk group (53 patients), and 25.6% and 0% in the high risk group (38 patients), respectively. CONCLUSIONS: In addition to pathological stage and tumor grade, LVI is an independent prognostic factor for disease specific survival in upper tract TCC. Patients in the high and/or intermediate risk groups may benefit from integrated therapies with surgery and postoperative systemic chemotherapy.  相似文献   
999.
PURPOSE: The indications for repeat prostate biopsy for persistently increased prostate specific antigen (PSA) in men with prostate cancer never detected on previous biopsy are not clear. In this study we determined that PSA adjusted for transition zone (TZ) epithelial volume is the most powerful predictor for detecting prostate cancer on repeat biopsy. MATERIALS AND METHODS: Repeat prostate biopsies including additional TZ cores were performed in 75 men with PSA between 4.0 and 10.0 ng/ml. TZ epithelial volume was calculated by multiplying TZ volume by the percent of epithelium, which was measured by morphometric analysis using image analysis computer software. RESULTS: Prostate cancer was detected on repeat biopsy in 19 of the 75 patients. Patients with prostate cancer had a significant smaller percent area of epithelium or glandular lumen than those without cancer. In patients without prostate cancer TZ epithelial volume significantly correlated with total PSA. According to ROC analysis PSA adjusted for TZ epithelial volume had the greatest AUC for cancer detection (0.879). This parameter was able to avoid more than 90% of unnecessary repeat biopsies with 90% sensitivity. Multiple logistic regression analysis showed that PSA complex adjusted for TZ epithelial volume was the significant independent predictor of cancer. CONCLUSIONS: PSA adjusted for TZ epithelial volume is the most powerful predictor of cancer in men who have undergone previous negative prostate biopsies and in whom PSA remains between 4.0 and 10.0 ng/ml.  相似文献   
1000.
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