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   17988篇
  免费   848篇
  国内免费   115篇
耳鼻咽喉   147篇
儿科学   249篇
妇产科学   127篇
基础医学   2174篇
口腔科学   374篇
临床医学   1281篇
内科学   4401篇
皮肤病学   470篇
神经病学   1110篇
特种医学   841篇
外科学   3229篇
综合类   81篇
一般理论   1篇
预防医学   658篇
眼科学   314篇
药学   1309篇
中国医学   47篇
肿瘤学   2138篇
  2023年   103篇
  2022年   229篇
  2021年   393篇
  2020年   210篇
  2019年   293篇
  2018年   374篇
  2017年   278篇
  2016年   371篇
  2015年   408篇
  2014年   498篇
  2013年   593篇
  2012年   975篇
  2011年   1114篇
  2010年   656篇
  2009年   498篇
  2008年   951篇
  2007年   1028篇
  2006年   1017篇
  2005年   1010篇
  2004年   1059篇
  2003年   1024篇
  2002年   962篇
  2001年   385篇
  2000年   374篇
  1999年   396篇
  1998年   239篇
  1997年   171篇
  1996年   154篇
  1995年   150篇
  1994年   137篇
  1993年   140篇
  1992年   266篇
  1991年   240篇
  1990年   246篇
  1989年   245篇
  1988年   192篇
  1987年   219篇
  1986年   171篇
  1985年   164篇
  1984年   117篇
  1983年   97篇
  1982年   44篇
  1981年   58篇
  1979年   96篇
  1978年   45篇
  1977年   59篇
  1974年   53篇
  1971年   41篇
  1969年   46篇
  1968年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Some chordomas have a very poor prognosis because of their aggressive growth nature, but the efficacy of repeat operations for these cases has not been well documented. This report concerns 3 patients with aggressive chordoma of the clivus, who underwent operations 6 to 12 times over a period of 8 to 17 years because of symptomatic regrowth. Overall mean interval between repeat operations was 18 months with a range from 5 to 57 months and survival times were 9 to19 years after the first surgery. Main symptoms before each operation were diplopia and visual disturbance. Repeat palliative operations by intentional extradural debulking of the tumour to decompress offending neural structures, as well as maximal removal of the tumour, using appropriate skull base approaches, can mitigate progressive symptoms, and may result in better quality and some prolongation of life, although our patients gradually deteriorated neurologically throughout the clinical course.  相似文献   
13.
Two hybridomas secreting two monoclonal antibodies IgG1 B1.4 and IgG2a B1.6 were obtained by immunizing BALB/c mice with human bladder cancer cell line EJ-1. In immunohistochemical staining of cryopreserved tissues, B1.4 reacted with 0 of 9 grade 1 TCC, 6 of 11 grade 2, all of 6 grade 3 and five metastatic specimens. The antigen recognized by B1.4 was not expressed by normal urothelial cells but were expressed by vascular endothelial cells and muscle of tunica media. The target antigen of B1.6 was expressed by normal urothelial cells and all grade of TCC. In this study, it was demonstrated that poorly differentiated bladder cancer and metastatic specimens of bladder cancer express a vascular carbohydrate antigen. Taking the escape mechanism of immune surveillance, into consideration, it is possible that the antigen recognized by B1.4 is an indicator of metastatic potential of bladder cancer.  相似文献   
14.
A bstract The purpose of this study was to assess the efficacy of nasal mask bi-level positive airway pressure (BiPAP) support in managing respiratory failure following cardiovascular surgery. A total of 20 patients requiring postoperative prolonged respiratory support of 72 hours or longer were studied. BiPAP support was used for eight patients (BiPAP group); the other 12 patients were managed using ordinary oxygen mask treatment (control group). The mean age of the BiPAP group and control group was 65 and 58 years of age, respectively. The mean period of postoperative endotracheal intubation of the BiPAP group and control group was 12 ± 5 days and 7 ± 1 days, respectively. Reintubation was necessary in two patients of the control group. The BiPAP group patients required no reintubation. BiPAP support was discontinued within 48 hours in 6 out of 8 patients. The respiratory rates of control group increased (p < 0.1) 24 hours after extubation, however, the respiratory rates of the BiPAP group remained unchanged. The values of the respiratory index of the BiPAP group improved significantly (p < 0.01) after BiPAP management (from 1.5 ± 0.2 to 0.9 ± 0.2). The values of the control group, however, remained unchanged. A-aDO2 and Qs/Qt decreased (p < 0.1) in the BiPAP group. There were no significant differences in central venous pressure or circulatory status between the two groups. In conclusion, BiPAP support is a noninvasive management technique for postoperative respiratory failure and may also prevent prolonged endotracheal intubation.  相似文献   
15.
16.
We examined responses of renal nerve activity, urine flow, and urinary Na+ excretion to a hypertonic NaCl infusion in chronically instrumented conscious rabbits with unilateral renal denervation. The intravenous infusion of 20% NaCl, at 0.2 ml/min for 30 min, increased plasma osmolality by 27 +/- 5 mOsm/kg, and plasma Na+ by 16 +/- 3 mEq/l, and decreased hematocrit by 5 +/- 1%. These changes were accompanied by a marked decrease in renal nerve activity by 82 + 7%. Urine flow and urinary Na+ excretion increased gradually and peaked at the end of infusion. The innervated kidney excreted 23.3 +/- 3.3 ml urine and 5.5 +/- 0.7 mEq Na+ for the subsequent 60 min. However, the contralateral denervated kidney excreted only 9.5 +/- 2.0 ml urine and 2.2 +/- 0.6 mEq Na+; these values were significantly less than those of the innervated kidney. To examine the role of the sinoaortic and cardiopulmonary baroreceptors and the hepatic nerves in the response of renal nerve activity to the hypertonic NaCl infusion, renal nerve activity was examined in conscious rabbits with sinoaortic baroreceptor denervation (SAD) plus vagotomy and/or section of the anterior and posterior hepatic nerves (SAPH). In rabbits with SAD plus vagotomy or SAPH, the NaCl infusion also decreased renal nerve activity. After combining SAPH and SAD plus vagotomy, the decrease in renal nerve activity was completely blocked. These results indicate that hypertonic NaCl infusion elicits a marked decrease in renal nerve activity which is mediated predominantly by sinoaortic and cardiopulmonary baroreflexes and the hepatic nerves, and that the decrease in renal nerve activity plays an important role in the augmentation of renal function.  相似文献   
17.
The reflex effects of hepatic osmoreceptors on the renal sympathetic nerve activity (RNA) were studied in 30 pentobarbital anesthetized, vagotomized and sino-aortic baroreceptor denervated (SAD + VD) rabbits. The changes in mean arterial pressure (MAP), heart rate (HR), and RNA were examined when 9% NaCl, 6.5% LiCl or 50% glucose solution was infused into the hepatic portal vein at a rate of 0.15 ml/kg/min for 10 min. Infusion of 9% NaCl solution into the hepatic portal vein increased the plasma osmolality by 10.8 +/- 1.0 mOsmol/kg from the control level in the blood of the hepatic portal vein and by 2.8 +/- 2.0 mOsmol/kg from the control level in the systemic blood. MAP was significantly elevated by 10.2 +/- 5.0 mmHg but HR did not change with hepatic portal infusion of 9% NaCl solution. Intraportal infusion of 9% NaCl solution significantly decreased the RNA by 28.6-34.2% from the control level, 6.5% LiCl solution by 28.6 +/- 4.7%, and 50% glucose solution by 26.2 +/- 3.0%. Femoral arterial infusion of hypertonic NaCl solution, however, did not evoke any significant change in RNA in SAD + VD rabbits. These findings suggest that increases in osmolality and NaCl concentration in the systemic circulation do not result in a decrease of RNA. Furthermore, after section of the anterior and posterior plexus of the hepatic nerve, hepatic portal infusion of hypertonic NaCl solution elicited no change in RNA. The present data indicate that an increase in osmolality in the hepatic portal venous blood results in a reflex decrease of RNA. This reflex may be important for restoration of a postprandial increase in osmolality.  相似文献   
18.
This report describes our experience with a 60 year old male who suffered from a recrudescence of groove pancreatitis. He had been treated by conservative medication therapy by proton pump inhibitor used for therapy of duodenal ulcer, and was in remission. During a follow-up one year later, endoscopy revealed gastric cancer, for which a proximal gastrectomy and vagotomy were performed. The patient continues to remain in remission for the groove pancreatitis. Our experience with the clinical course of this disease, in which treatment for duodenal ulcer was used effectively, offers new insights into the progression and therapy of groove pancreatitis.  相似文献   
19.
We report here an unusual case of fibrous histiocytoma in which an area of xanthogranuloma was observed histologically. Our case suggests that adult xanthogranuloma is a variant of fibrous histiocytoma.  相似文献   
20.
To evaluate the extent and characteristics of infarct areas, we performed indium-111 monoclonal antimyosin Fab (InAM), thallium-201 (TL) and Tc-99m pyrophosphate (PYP) imagings in 17 patients with acute myocardial infarction, and tried to find out the mechanism that causes difference of these imagings. In each study, the extent scores as an index of the infarct area were obtained by single photon emission computed tomography (SPECT), and comparisons were made between the results obtained. The overlap between InAM and TL imagings obtained by SPECT was evaluated. Location, severity, extent and patterns of accumulation were compared between InAM and PYP with both planar image and SPECT. The extent scores of InAM correlated well with those of TL (r = 0.73, p < 0.01). However, the overlap of both methods was recognized in 8 of 17 patients, in whom wall thickness of the infarct area as obtained by echocardiography was well preserved. The left ventricular regional asynergy was mild in 6 of these 8 patients. Coronary angiography showed poor or no collateral circulation in these cases. Although there were generally close correlations of the extent scores between InAM and PYP, discrepancy was noted in 2 cases for location; 2 for severity, 5 for extent, and 3 for patterns of accumulation. These differences may be attributed to the timings of imaging, coronary reperfusion and different mechanisms of accumulation. In conclusion, the extent of acute myocardial infarction obtained by InAM correlates well with those obtained by TL and PYP, with some exceptions.  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