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   10606篇
  免费   481篇
  国内免费   77篇
耳鼻咽喉   98篇
儿科学   233篇
妇产科学   82篇
基础医学   1402篇
口腔科学   227篇
临床医学   627篇
内科学   2828篇
皮肤病学   129篇
神经病学   698篇
特种医学   376篇
外科学   2006篇
综合类   61篇
预防医学   266篇
眼科学   187篇
药学   529篇
中国医学   49篇
肿瘤学   1366篇
  2024年   10篇
  2023年   93篇
  2022年   173篇
  2021年   279篇
  2020年   144篇
  2019年   189篇
  2018年   257篇
  2017年   183篇
  2016年   267篇
  2015年   221篇
  2014年   332篇
  2013年   385篇
  2012年   692篇
  2011年   711篇
  2010年   434篇
  2009年   351篇
  2008年   686篇
  2007年   722篇
  2006年   700篇
  2005年   732篇
  2004年   676篇
  2003年   628篇
  2002年   663篇
  2001年   112篇
  2000年   92篇
  1999年   117篇
  1998年   175篇
  1997年   140篇
  1996年   111篇
  1995年   108篇
  1994年   88篇
  1993年   90篇
  1992年   62篇
  1991年   69篇
  1990年   46篇
  1989年   53篇
  1988年   58篇
  1987年   49篇
  1986年   29篇
  1985年   23篇
  1984年   30篇
  1983年   26篇
  1982年   24篇
  1981年   22篇
  1980年   22篇
  1979年   7篇
  1978年   13篇
  1977年   12篇
  1976年   8篇
  1970年   8篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
982.
983.
The incidence of a tracheal bronchus—that is, a congenitally abnormal bronchus originating from the trachea or main bronchi–is 0.1%–2%. Serious hypoxia and atelectasis can develop in such patients with intubation and one-lung ventilation. We experienced a remarkable decrease in peripheral oxygen saturation () and a rise in airway pressure during placement of a double-lumen endobronchial tube in a patient with patent ductus arteriosus and tracheal bronchus. Substitution of the double-lumen tube with a bronchial blocker tube provided secure isolation of the lung intraoperatively. A type I tracheal bronchus and segmental tracheal stenosis were identified on postoperative three-dimensional (3D) computed tomographic (CT) images. Preoperative examination of chest X-rays, CT images, and preoperative tracheal 3D images should preempt such complications and assist in securing safe and optimal one-lung ventilation.  相似文献   
984.
BACKGROUND AND OBJECTIVE: Several studies of real-time endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) have reported a sensitivity of approximately 90% in the diagnosis of mediastinal and hilar malignancies. However, few studies have addressed its role in the diagnosis of sarcoidosis. The aim of the present study was to assess the utility of EBUS-TBNA in confirming a pathological diagnosis of sarcoidosis. METHODS: Fifteen consecutive patients with suspected sarcoidosis and mediastinal and/or hilar lymphadenopathy were investigated prospectively. EBUS-TBNA with an echo-bronchoscope and a dedicated echogenic 22-gauge needle was carried out in patients under conscious sedation, followed by conventional TBNA of the same lesion using a 19-gauge needle. RESULTS: EBUS-TBNA and/or TBNA demonstrated non-caseating epithelioid cell granulomas in 14 of 15 patients (93%). All 14 patients with a pathological diagnosis of sarcoidosis were considered to have sarcoidosis based on subsequent clinical assessments. The single patient with a negative EBUS-TBNA and TBNA had a malignant melanoma diagnosed following surgical biopsy. EBUS-TBNA confirmed a diagnosis of sarcoidosis in 13 of the 14 patients (93%) by identifying non-caseating epithelioid cell granulomas in 18 of 23 lymph nodes (78%) sampled. When two needle aspirates of one or two lymph nodes were carried out, the percentage positive pathological diagnosis for sarcoidosis for (i) EBUS-TBNA; (ii) TBNA; and (iii) the combination of EBUS-TBNA and TBNA were 93% (13 of 14 patients), 93% (13 of 14 patients) and 100% (14 of 14 patients), respectively. There were no complications associated with the procedures. CONCLUSION: EBUS-TBNA is less invasive and acceptably sensitive as a method for obtaining pathological confirmation of sarcoidosis.  相似文献   
985.
986.
BACKGROUND: Our study was planned to investigate the relationship between plasma levels of serum amyloid A protein (SAA) concentrations and the subsequent left ventricular systolic function in patients with acute myocardial infarction (AMI) treated with primary coronary angioplasty. METHODS AND RESULTS: Reperfusion by primary percutaneous coronary intervention was successful in 486 consecutive AMI patients who were admitted within 12 hours of onset. Plasma SAA concentrations were evaluated 24 hours after onset. Left ventricular (LV) function was serially determined by left ventriculography performed in the acute (soon after recanalization) and chronic phases (6 months after onset). (I) There was no significant correlation between SAA concentration and acute phase left ventricular ejection fraction (LVEF) or regional wall motion (RWM). (II) The SAA concentration was significantly correlated with both highly sensitive C-reactive protein (hs-CRP) and the peak-CK value (hs-CRP: r = 0.69, P < 0.0001, peak-CK: r = 0.21, P = 0.0003). (III) SAA was significantly negatively correlated with both LVEF and RWM in the chronic phase (LVEF: r = -0.42, P = 0.001; RWM: r = -0.41, P = 0.007). (IV) The plasma level of SAA also showed a significant negative correlation with the differences in LVEF between the 2 stages (delta-LVEF) (r = -0.43, P = 0.02). CONCLUSION: In the setting of AMI, plasma SAA concentrations may be closely related to subsequent left-ventricular systolic dysfunction.  相似文献   
987.
Klotho, a regulatory factor implicated in countering the aging process, has been reported to ameliorate endothelial dysfunction in vivo. To clarify whether Klotho protein directly affects endothelial cell function, we studied the effects of membrane-form Klotho on manganese superoxide dismutase (Mn-SOD) expression and nitric oxide production in human umbilical vein endothelial cells (HUVEC). We incubated HUVEC with conditioned medium from COS-1 cells transfected with expression vector, pCAGGS-klotho (Klotho-CM) or a recombinant, purified 6His-tagged Klotho protein. Both Klotho-CM and 6His-tagged Klotho protein enhanced Mn-SOD expression by approximately two-fold, partially via activation of the cAMP signaling pathway. Furthermore, Klotho-CM increased nitric oxide production, which also contributed to the up-regulation of Mn-SOD. Using the oxidation-sensitive dye dihydroethidium, we found that Klotho inhibited angiotensin II-induced reactive oxygen species production in HUVEC. These findings provide new insights into the mechanisms of Klotho action and support the therapeutic potential of membrane-form Klotho to regulate endothelial function. Hiromi Rakugi and Naomichi Matsukawa contributed equally to this work.  相似文献   
988.
989.
Basaloid squamous cell carcinoma (BSC) of the esophagus is a rare malignant disease. We report here a patient with recurrent esophageal BSC, who was successfully treated by systemic chemotherapy containing 5-fluorouracil (5-FU) and cisplatin (CDDP). A 57-year-old woman was diagnosed as having SCluamous cell carcinoma of the esophagus upon endoscopic examination. Curative esophagectomy with lymph node dissection was performed under the thoracoscope. The pathological diagnosis of the surgical specimen was BSC. Five months after operation, the patient was diagnosed as having a recurrence of the BSC with metastases to the liver and spleen, and a right paraclavicular lymph node. She was given systemic chemotherapy consisting of continuous infusion of 800 mg/d of 5-FU and 3 h infusion of 20 mg/d of CDDP for 5 consecutive days every 4 wk. The metastatic lesions in the spleen and right paraclavicular lymph node disappeared, and the liver metastasis was apparently reduced in size after 2 courses of chemotherapy. The tumor regression was seen over 6 courses, with progression afterwards. Although subsequent treatment with CPT-11 and CDDP was not effective, docetaxel and vinorelbine temporarily controlled the tumor growth for 2 mo. 5-FU and CDDP combination may be useful for the patients with advanced BSC.  相似文献   
990.
There are several cofactors which affect body iron metabolism and accelerate iron overload. Alcohol and hepatic viral infections are the most typical examples for clarifying the role of cofactors in iron overload. In these conditions, iron is deposited in hepatocytes and Kupffer cells and reactive oxygen species (ROS) produced through Fenton reaction have key role to facilitate cellular uptake of transferrin-bound iron. Furthermore,hepcidin, antimicrobial peptide produced mainly in the liver is also responsible for intestinal iron absorption and reticuloendothelial iron release. In patients with ceruloplasmin deficiency, anemia and secondary iron overload in liver and neurodegeneration are reported.Furthermore, there is accumulating evidence that fatty acid accumulation without alcohol and obesity itself modifies iron overload states. Ineffective erythropoiesis is also an important factor to accelerate iron overload,which is associated with diseases such as thalassemia and myelodysplastic syndrome. When this condition persists, the dietary iron absorption is increased due to the increment of bone marrow erythropoiesis and tissue iron overload will thereafter occurs. In porphyria cutanea tarda, iron is secondarily accumulated in the liver.  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