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   17530篇
  免费   933篇
  国内免费   65篇
耳鼻咽喉   236篇
儿科学   459篇
妇产科学   373篇
基础医学   2531篇
口腔科学   302篇
临床医学   1592篇
内科学   3491篇
皮肤病学   518篇
神经病学   2165篇
特种医学   993篇
外科学   2350篇
综合类   126篇
一般理论   4篇
预防医学   884篇
眼科学   288篇
药学   951篇
中国医学   62篇
肿瘤学   1203篇
  2023年   150篇
  2022年   246篇
  2021年   439篇
  2020年   295篇
  2019年   418篇
  2018年   447篇
  2017年   402篇
  2016年   499篇
  2015年   498篇
  2014年   694篇
  2013年   832篇
  2012年   1344篇
  2011年   1409篇
  2010年   811篇
  2009年   708篇
  2008年   1168篇
  2007年   1152篇
  2006年   1097篇
  2005年   1086篇
  2004年   932篇
  2003年   882篇
  2002年   799篇
  2001年   153篇
  2000年   128篇
  1999年   171篇
  1998年   187篇
  1997年   137篇
  1996年   139篇
  1995年   94篇
  1994年   90篇
  1993年   65篇
  1992年   50篇
  1991年   56篇
  1990年   37篇
  1989年   24篇
  1988年   31篇
  1987年   32篇
  1986年   25篇
  1985年   30篇
  1984年   24篇
  1983年   24篇
  1982年   31篇
  1981年   24篇
  1980年   36篇
  1979年   27篇
  1978年   21篇
  1977年   33篇
  1976年   19篇
  1975年   17篇
  1933年   15篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
PURPOSE: To perform a multicentre intercomparison study of treatment concepts for MRI assisted brachytherapy of cervix cancer based on recommendations of the Gynaecological GEC-ESTRO Working Group. METHODS: Each participating centre (IGR Paris, University Hospital Leuven, Medical University of Vienna) contributed data of one patient with comparable clinical features. GTV, High Risk CTV (HR CTV), Intermediate Risk CTV (IR CTV) and organ walls of bladder, rectum and sigmoid colon were delineated at the time of each brachytherapy fraction on axial MR images with the applicator in place. Dose-volume histograms were calculated to evaluate doses to tumour, target volumes and organs at risk. Dose values were biologically normalised to equivalent doses in 2 Gy fractions (EQD(2), equivalent to 50 cGy/h low dose rate) applying the linear-quadratic model. RESULTS: Total doses to point A from external beam therapy plus brachytherapy ranged from 85 to 91 Gy and were close to the dose covering 90% of HR CTV (D90=85-87 Gy). D90 of IR CTV was within 69-73 Gy. Doses to organs at risk were comparable. CONCLUSIONS: This study indicates the feasibility of the GEC-ESTRO recommendations. Despite different treatment concepts, biologically normalised total doses to tumour, target volumes and organs at risk were comparable.  相似文献   
992.
Persistence or recurrent cancer in the anterior commissure (AC) after primary radiotherapy may remain localized to its pretreatment anatomical site. If so, endoscopic CO2 laser excision, in experienced hands, may achieve complete tumor excision and result in cure for many patients. Occasionally, second and third recurrences may be similarly salvaged by further endoscopic surgery. The use of the vertical hemilaryngectomy is an alternative treatment for similar localized lesions, with a higher first time surgical tumor eradication rate, but with a more protracted hospitalization and a less satisfactory voice and swallowing outcome. In both types of such surgical salvage, CT scanning must demonstrate no evidence of cartilage invasion or destruction. When there is evidence of minimal thyroid cartilage invasion, then the supracricoid partial laryngectomy is an alternative conservation option, and is likely to result in a cure, with the retention of a voicing larynx without a stoma. When the tumor has increased in size from the original pretreatment dimension and/or site, then imaging must be used to identify possible cartilage invasion, in which case the likelihood of tumor eradication by endoscopic or external vertical partial laryngectomy is highly unlikely. The indications for the routine use of total laryngectomy for the treatment of recurrent or persistent cancer involving the AC must be reviewed; there is current evidence that cure can be achieved by a less radical procedure. However, total laryngectomy may remain the only treatment option for advanced or aggressive first time recurrence, or in patients who develop subsequent recurrence following previous less aggressive surgery (endoscopic or external).  相似文献   
993.
Risk of cancer among relatives of patients with glioma.   总被引:1,自引:0,他引:1  
We report a population-based, retrospective study of 396 Icelandic people diagnosed with glioma in the years 1940-1995. The purpose of this study was to test whether astrocytomas, other glial tumors, other central nervous system tumors, or other cancers aggregate in families identified through glioma probands who were of Icelandic origin. Pedigrees of the 396 cases were traced by the Genetical Committee of the University of Iceland and linked to the Icelandic Cancer Registry. A total of 25,546 relatives, including 2,080 individuals with cancer were identified within these pedigrees. There was no statistically significant increase of glioma in relatives of glioma patients, nor was there any statistically significant increase in risk for other central nervous system tumors. There was no overall increase in incidence of all cancer combined, nor of specific common cancers (lung, prostate, breast, stomach, and colorectal) and uncommon cancers (melanoma and pancreas) in the relatives of glioma patients. Our results do not support the hypothesis of a familial aggregation of glioma indicative of a glioma susceptibility gene.  相似文献   
994.
OBJECTIVE: The aim of this study was to search for activation markers of peripheral leukocytes in experimental preeclampsia in the rat. STUDY DESIGN: Experimental preeclampsia was induced in 14-day-pregnant rats by infusion of endotoxin (1.0 microg/kg body weight). For comparison, rats with normal pregnancies that were infused with sodium chloride solution and cyclic rats that were infused with either endotoxin or sodium chloride solution were used. At various points before and after the infusion, blood samples were withdrawn and analyzed by means of whole-blood flow cytometry to evaluate expression of inflammation-associated adhesion molecules (CD11b, CD11a, CD49d, and CD62L) and CD14 on the leukocytes. RESULTS: Normal pregnancy was associated with increased CD11b (granulocytes and monocytes), CD11a (monocytes and lymphocytes), and CD49d (granulocytes, monocytes, and lymphocytes) expression. In addition to these changes found in normal pregnancy, reduced CD62L and increased CD11a and CD49d expression was found on granulocytes after endotoxin treatment of pregnant rats. No effect of endotoxin was observed in cyclic rats. CONCLUSION: Leukocytes of rats with experimental preeclampsia and, to a lesser extent, those of rats with normal pregnancies had an activated phenotype. These results are consistent with our previous findings in human subjects and suggest that (experimental) preeclampsia results from a generalized inflammatory response.  相似文献   
995.
996.

Background  

To investigate if positive changes or maintenance high scores on potential behavioral determinants of fruit and vegetable (F&V) intake are associated with increased or maintenance favorable levels of F&V intake frequency in the same time lapse or later in time. Data were used from two intervention studies in the Netherlands: the Schoolgruiten Project and the Pro Children Study.  相似文献   
997.

Background  

Social networks and social support are supposed to contribute to the development of unequal health within populations. However, little is known about their socio-economic distribution. In this study, we explore this distribution.  相似文献   
998.

Background  

Childhood obesity is a serious public health problem and epidemiological studies are important to identify predictive factors. It is the aim of this study to analyse factors associated with overweight/obesity in samples of German children.  相似文献   
999.
Paraffin-embedded sections of vulvar squamous-cell carcinomas and of normal vulvar tissues were examined for HPV types 6, 11, 16, 18 and 33 by the polymerase chain reaction. Overall, 19 of 62 tumours harboured HPV DNA of types 16, 18 or 33. HPV types 6 and 11 were not detected. HPV DNA was found in 61% of tumours with adjacent intraepithelial neoplasia (VIN III), and in 13% of tumours without associated VIN III. HPV DNA was not detected in any of 101 normal vulvar tissues. HPV DNA was found more often in younger women, in patients with VIN III-associated tumours, and in those with multicentric anogenital neoplasia. This points to the existence of a subset of vulvar carcinomas preceded by intraepithelial neoplasia, with HPV as a major factor in carcinogenesis. HPV also seems to be an important factor in the development of multiprimaries in these patients. The 2 groups of patients with vulvar carcinoma did not differ with regard to prognosis, as estimated by the risk of recurrence after primary surgery.  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