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   9418篇
  免费   320篇
  国内免费   50篇
耳鼻咽喉   66篇
儿科学   169篇
妇产科学   110篇
基础医学   1103篇
口腔科学   199篇
临床医学   636篇
内科学   2455篇
皮肤病学   140篇
神经病学   556篇
特种医学   434篇
外科学   1468篇
综合类   41篇
预防医学   308篇
眼科学   68篇
药学   604篇
中国医学   39篇
肿瘤学   1392篇
  2024年   42篇
  2023年   91篇
  2022年   152篇
  2021年   275篇
  2020年   171篇
  2019年   191篇
  2018年   209篇
  2017年   170篇
  2016年   204篇
  2015年   219篇
  2014年   328篇
  2013年   364篇
  2012年   592篇
  2011年   632篇
  2010年   342篇
  2009年   263篇
  2008年   453篇
  2007年   453篇
  2006年   477篇
  2005年   466篇
  2004年   440篇
  2003年   408篇
  2002年   405篇
  2001年   179篇
  2000年   178篇
  1999年   201篇
  1998年   130篇
  1997年   94篇
  1996年   82篇
  1995年   75篇
  1994年   81篇
  1993年   69篇
  1992年   137篇
  1991年   123篇
  1990年   134篇
  1989年   154篇
  1988年   129篇
  1987年   113篇
  1986年   90篇
  1985年   68篇
  1984年   56篇
  1983年   57篇
  1981年   20篇
  1979年   22篇
  1978年   24篇
  1977年   21篇
  1975年   20篇
  1974年   24篇
  1973年   21篇
  1968年   18篇
排序方式: 共有9788条查询结果,搜索用时 15 毫秒
81.
82.
Sawada M  Watanabe S  Tsuda H  Kano T 《Anesthesia and analgesia》2002,94(6):1416-20, table of contents
Radiofrequency ablation (RFA) therapy using an active needle electrode inserted into liver tumors has been used clinically. To avoid hyperthermia, we investigated the relationship between the total output energy of the applied radiofrequency wave and changes in body temperature (BT) in patients receiving RFA. Fifteen patients undergoing RFA of liver tumors with general anesthesia were enrolled. The total output energy of radiofrequency waves was calculated from the power and duration of RFA. Changes in rectal (T(rect)) and tympanic temperatures were measured throughout the study. The mean number of liver tumors per patient was 1.7 +/- 1.3. The mean RFA time was 30.0 +/- 26.3 min. The mean total output energy was 125,935 +/- 114,506 J. The mean value of T(rect) increased from 36.3 degrees C +/- 0.5 degrees C to 37.0 degrees C +/- 1.0 degrees C (P < 0.01). A linear correlation was obtained between the total output energy and the changes in T(rect), indicating that T(rect) increased approximately by 1 degrees C for every 3000 J/kg of total output energy. The increase in BT during RFA of liver tumors under general anesthesia is predictable. Close observation of total output energy delivered and BT are required, and preparation of cooling measures is important, in RFA of liver tumors. IMPLICATIONS: The increase in body temperature (BT) is predictable during radiofrequency ablation (RFA) of liver tumors under general anesthesia. Close observation of total output energy delivered and BT are required, and preparation of cooling measures is important, in RFA of liver tumors.  相似文献   
83.
SUMMARY BACKGROUND DATA: Quick intraoperative parathyroid hormone assays are widely used as a guide to the adequacy of resection during parathyroid surgery. However, some authors have reported a 15% error rate of these assays because of the presence of false-positive and false-negative results. Recently the authors have found that most commercial intact PTH (iPTH) assays cross-react with non-(1-84) PTH (likely 7-84 PTH) and that the proportional levels of non-(1-84) PTH in patients were variable in a much wider range, accounting mostly for 20% to 60% of the immunoreactivity in samples obtained from hyperparathyroid patients. A cyclase activating PTH (CAP) measured by a novel immunoradiometric assay was shown to measure specifically 1-84 PTH. Using a CAP assay, the authors studied the rate of decline of CAP after parathyroidectomy and compared it with iPTH as measured by the Nichols intact PTH immunoradiometric assay. METHODS: This study comprised 29 patients with primary hyperparathyroidism (pHPT) caused by a single adenoma and 7 patients with secondary hyperparathyroidism (secondary HPT) who underwent parathyroidectomy. Blood samples were drawn after anesthesia, before excision of one enlarged parathyroid gland in pHPT and of the last gland in secondary HPT, and at 5, 10, and 15 minutes after excision. The 7-84 PTH level was calculated by subtracting the CAP value from the iPTH value. RESULTS: The percentage of 7-84 PTH in iPTH in plasma samples was 27.5 +/- 14.4% in pHPT and 39.6 +/- 15.1% in secondary HPT. In pHPT patients the plasma CAP and iPTH value decreased to 23.4 +/- 10.8 and 32.0 +/- 11.3% of the preexcision level at 5 minutes, 10.6 +/- 7.7 and 21.1 +/- 8.8% at 10 minutes, and 8.5 +/- 4.9 and 16.1 +/- 6.8% at 15 minutes after removal of the enlarged gland, respectively. At 5 minutes, CAP levels of all 29 pHPT patients had decreased to less than 40% of the preparathyroidectomy level; however, 7 (24%) patients still had an iPTH level of more than 40%. In secondary HPT patients, CAP and iPTH values had dropped to 43.3 +/- 20.2 and 66.1 +/- 19.7% at 5 minutes, 28.6 +/- 16.6 and 53.6 +/- 18.1% at 10 minutes, and 14.2 +/- 9.0 and 41.0 +/- 12.9% at 15 minutes after removal of the last enlarged gland, respectively. At 10 minutes, CAP levels of all seven secondary HPT patients had decreased to less than 50% of the preexcision level; however, three (43%) patients still had an iPTH level of more than 50%. In pHPT and secondary HPT, the 7-84 PTH level had dropped to 57.4 +/- 85.9 and 62.1 +/- 84.9%, respectively, of the preexcision value 15 minutes after removal of the enlarged gland or glands. CONCLUSIONS: The percentage of 7-84 PTH in iPTH in plasma samples varies substantially between patients with HPT. In both pHPT and secondary HPT, the plasma CAP value decreased more rapidly than iPTH after parathyroidectomy, depending on the amount of 7-84 PTH in circulation. These results suggest that the CAP assay may be a more useful adjunct to parathyroidectomy than the currently used iPTH assay.  相似文献   
84.
We herein describe the case of a 48-year-old man who presented to our hospital with abdominal distension and pain. Preoperative studies including abdominal ultrasonography and computed tomography failed to determine the cause of the pain. At laparotomy, a giant cystic tumor of the small bowel mesentery was found. Histologically, the tumor was diagnosed as a cystic lymphangioma. Although mesenteric lymphangiomas are rare, especially in adults, they should be considered as a possible cause of acute abdomen. Received: August 8, 2001 / Accepted: January 8, 2002  相似文献   
85.
Intraoperative MRI (iMR) and neuronavigation have substantially changed the principles of surgery for brain tumors. iMR provides updated information on anatomical data and unanticipated brain events, thereby allowing safer and more accurate surgery. We herein report a case of unanticipated intracranial hemorrhage in an iMR imaging suite. The patient was a 53-year-old man with a chief complaint of generalized convulsion. MRI showed a lesion in the right temporal lobe about 6.0 cm in diameter. The tumor was resected using an iMR system and neuronavigation. The first iMR images showed a residual tumor in the medial temporal lobe. No brain events were detected at this time. We obtained updated navigation data and performed additional resection. After completion of the planned tumor resection, additional iMR images were taken. The second iMR images confirmed that the tumor had been completely removed, but they also revealed a contra-lateral subdural hemorrhage. After expedited closure of the original incision, left unilateral craniotomy was performed and the hematoma was evacuated. Fortunately, the patient had no new neurological deficits. The use of iMR imaging allowed the complete removal of the tumor and facilitated prompt and effective identification of an unanticipated life-threatening complication.  相似文献   
86.
Background: To treat advanced heart failure due to idiopathic dilated cardiomyopathy, surgical ventricular restoration with mitral reconstruction was conducted and evaluated. Methods: In 95 patients (81 men, mean age: 54 years), New York Heart Association class III/IV was 44/51, and 33 patients (36%) were inotropic dependent preoperatively. Mitral regurgitation (≥2+) was noted in all patients. All patients underwent left ventriculoplasty (septal anterior ventricular exclusion in 38, partial left ventriculectomy in 57) and mitral reconstruction (repair 53, replacement 42). Fifty-two patients (55%) had concomitant tricuspid repair. Intra-aortic balloon pumping and left ventricular assist device was used in 24 patients and two patients, respectively. Results: Hospital mortality was 11.6% (11 of 95), with 6.6% (5 of 76) in elective and 31.6% (6 of 19) in emergency operations. The ejection fraction and cardiac index increased from 22.3 ± 6.3% to 27.2 ± 8.0% and from 2.3 ± 0.5 ml/m2/min to 2.8 ± 0.5 ml/m2/min, respectively (p < 0.001). The endodiastolic volume index, endosystolic volume index and diastolic dimension decreased from 232.9 ± 56.1 ml/m2 to 160.0 ± 49.8 ml/m2, from 178.9 ± 46.7 ml/m2 to 113.8 ± 44.7 ml/m2 and from 82.0 ± 9.0 mm to 68.9 ± 11.6 mm, respectively (p < 0.001). Late death occurred in 27 patients with 22 cardiac deaths. The mean NYHA class was 1.7 among the survivors. One-, 3- and 5-year survival rates were 72.8%, 61.4% and 50.5%, respectively. In the 62 patients who were non-inotropic dependent preoperatively, 1-, 3-, and 5-year survival rates (81.8%, 73.7% and 62.9%) were significantly better than the inotropic-dependent group (55.3%, 37.3% and 28.0%). Patients with mitral annuloplasty showed a significantly higher 5-year survival rate than patients with mitral valve replacement (59.6% vs 43.6%) in univariate analysis. By application of the exclusion site selection method, the two different ventriculoplasty procedures did not show significant difference in survival rates. Multivariate analysis showed that preoperative inotropes and old age were significant predictors for postoperative mortality. Conclusion: The selected ventriculoplasty in combination with mitral annuloplasty is a useful option for patients with an extremely dilated left ventricle in idiopathic dilated cardiomyopathy. Surgery should be considered before inotropic dependency occurs when prior medical treatment has failed.  相似文献   
87.
We report a case of adenocarcinoma of the minor duodenal papilla, a rare type of duodenal neoplasm. A 76-year-old man with a history of surgery for rectal cancer and gastric cancer was referred to us after a follow-up upper gastrointestinal endoscopy revealed an abnormal elevation in the minor duodenal papilla. The pathological diagnosis of a biopsy specimen was adenocarcinoma. Preoperative examination of other organs revealed a tumor in the ascending colon, which was also identified as adenocarcinoma. We performed synchronous pancreatoduodenectomy and ileocecal resection with lymph node dissection. Histopathological examination of the resected specimen revealed that the papilla tumor arose from the duodenal mucosa and infiltrated the submucosa of the duodenal wall, but not the pancreatic parenchyma. Based on these findings, we diagnosed primary adenocarcinoma of the minor duodenal papilla. To our knowledge, this is only the sixth such case reported in the English-language literature, and we review all six cases after this case report.  相似文献   
88.
A 65-year-old male who had previously received curative treatment for a pineal tumor presented with an extremely rare case of primary central nervous system (CNS) primitive neuroectodermal tumor (PNET) of the spinal cord manifesting as progressive tetraparesis. Although the histology was not verified, highly radiosensitive tumor was suspected because of the benign clinical course for over 20 years after only radiation therapy. Magnetic resonance imaging demonstrated an intramedullary tumor extending from C5 to T1. He underwent partial resection and histological examination revealed blue tumor with undifferentiated small round cells. Immunohistochemically, c-kit was negative but CD99 was strongly and diffusely positive. Therefore, rearrangement of the Ewing sarcoma gene was examined to determine the presence of peripheral type of PNET. The results were negative and systemic workup revealed no other disease. These findings led to the diagnosis of primary intramedullary CNS PNET of the spinal cord, and suggested that the spinal cord tumor occurred independently of the prior pineal disease. The residual tumor was controlled by postoperative local radiation therapy.  相似文献   
89.
We herein report a case of combined hepatic resection with inferior vena cava (IVC) and diaphragm resection, and reconstruction using an equine pericardial patch. A 54-year-old woman showed hepatic cancer recurrence on radiological imaging, with invasion to the caudate lobe of the liver, IVC, diaphragm, and adrenal gland. We resected 10 × 5 cm of the diaphragm. After dissecting the hepatic parenchyma, the caudate lobe was connected only to the IVC. Clamping of the IVC was performed between the IVC below the confluence of the hepatic vein and the suprarenal IVC. A 6 × 3-cm segment of the IVC was then resected. The IVC and diaphragm were reconstructed using an equine pericardial patch, as both defects were too large to repair without a patch. The equine pericardium represents a suitable graft material for repairing both the IVC and diaphragm. Further investigation is needed to determine the durability and anti-infection properties of equine pericardial grafts.  相似文献   
90.
Measuring the hepatic extraction fraction (HEF) of a hepatobiliary radiopharmaceutical helps to differentiate hepatocyte from biliary tract diseases, and it is generally performed using deconvolution analysis. In this study, we measured HEF using spectral analysis. With spectral analysis, HEF was calculated from (the sum of the spectral data obtained by spectral analysis--the highest frequency component of the spectrum) divided by (the sum of the spectral data) x 100 (%). We applied this method to dynamic liver scintigraphic data obtained from six healthy volunteers and from 46 patients with various liver diseases, using 99Tcm-N-pyridoxyl-5-methyltryptophan (PMT). We also measured HEF using deconvolution analysis, in which the modified Fourier transform technique was employed. The HEF values obtained by spectral analysis correlated closely with those obtained by deconvolution analysis (r = 0.925), suggesting our method is valid. The HEF values obtained by spectral analysis decreased as the severity of liver disease progressed. The values were 100.0 +/- 0.0%, 94.7 +/- 13.6%, 76.2 +/- 27.4%, 45.7 +/- 15.6%, 82.7 +/- 24.2% and 95.2 +/- 11.8% (mean +/- S.D.) for the normal controls (n = 6), mild liver cirrhosis (n = 16), moderate liver cirrhosis (n = 11), severe liver cirrhosis (n = 5), acute hepatitis (n = 8) and chronic hepatitis groups (n = 6), respectively. The HEF was obtained more simply and rapidly by spectral analysis than by deconvolution analysis. The results suggest that our method using spectral analysis can be used as an alternative to the conventional procedure using deconvolution analysis for measuring HEF.  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