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   36219篇
  免费   2864篇
  国内免费   368篇
耳鼻咽喉   393篇
儿科学   993篇
妇产科学   962篇
基础医学   4598篇
口腔科学   608篇
临床医学   3847篇
内科学   7747篇
皮肤病学   832篇
神经病学   2420篇
特种医学   1323篇
外科学   4906篇
综合类   1196篇
一般理论   32篇
预防医学   1987篇
眼科学   1583篇
药学   2730篇
中国医学   307篇
肿瘤学   2987篇
  2023年   271篇
  2022年   514篇
  2021年   966篇
  2020年   617篇
  2019年   784篇
  2018年   1002篇
  2017年   768篇
  2016年   877篇
  2015年   1048篇
  2014年   1388篇
  2013年   1661篇
  2012年   2352篇
  2011年   2470篇
  2010年   1424篇
  2009年   1278篇
  2008年   1927篇
  2007年   2004篇
  2006年   2000篇
  2005年   1938篇
  2004年   1703篇
  2003年   1592篇
  2002年   1425篇
  2001年   1131篇
  2000年   1065篇
  1999年   914篇
  1998年   394篇
  1997年   300篇
  1996年   278篇
  1995年   229篇
  1994年   209篇
  1993年   212篇
  1992年   459篇
  1991年   444篇
  1990年   427篇
  1989年   419篇
  1988年   370篇
  1987年   381篇
  1986年   329篇
  1985年   288篇
  1984年   213篇
  1983年   154篇
  1982年   113篇
  1981年   97篇
  1980年   106篇
  1979年   139篇
  1978年   97篇
  1977年   83篇
  1976年   83篇
  1975年   79篇
  1972年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
Background and objective  The purpose of this study is to assess whether Chinese children with high apnea–hypopnea index (AHI) are sleepier by a modified Epworth Sleepiness Scale (ESS). Materials and methods  Records were retrospectively reviewed. We included children who were between 3 and 12 years old, admitted for overnight polysomnogram because of suspected obstructive sleep apnea syndrome (OSAS). A modified ESS was used to assess excessive daytime sleepiness (EDS) of the children. Results  One hundred ninety-two Chinese children were included. Children with high AHI, defined as AHI > 5.0, were sleepier than children with AHI less than or equal to 5. After adjustment by age, gender, and obesity, children with high AHI remained significantly sleepier. Modified ESS was significantly correlated with AHI (rho = 0.124, 95% CI = 0.004–0.281). Modified ESS score of >8 was the best cutoff point with the sensitivity and specificity of 0.29 and 0.91, respectively. The odds ratio of children with modified ESS > 10 having high AHI was 4.231 (95%CI = 1.248 to 14.338) and children with modified ESS > 8 had the highest odds ratio, 4.295(95%CI = 1.66 to 11.1), of having high AHI. Conclusion   Chinese children with high AHI appear to be sleepier than children with low AHI. Children with suspected OSAS and high modified ESS, i.e., ESS > 8, had significantly higher odds ratio of having high AHI. Increased sleepiness is a specific but not a sensitive symptom in snoring children with high AHI. Screening for EDS in snoring children may help us identify those with high AHI and prioritize the management of those children. All authors worked and the study was carried out in Kwong Wah Hospital in Hong Kong. There was no conflict of interest and no specific source of funding for the study.  相似文献   
34.
35.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
36.
Hysterosalpingography was performed in 31 patients by means of a low-dose scanning-beam digital radiographic system. The technique permits adequate evaluation of gynecologic abnormalities while allowing significant reduction in radiation: 2.4-mR (6.1 X 10(-7) C/kg) exposure to the skin and 0.7-mrad (7 X 10(-6) Gy) mean dose to the ovaries per image obtained. Sixteen patients demonstrated readily recognizable and documented abnormalities, corroborated by laparoscopy, laparotomy, or other supportive evidence.  相似文献   
37.
The first‐order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103‐scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first‐order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low‐contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma.  相似文献   
38.
39.
Percutaneous intervention in saphenous vein grafts (SVG) carries a higher risk of distal embolization than intervention in a native vessel, and use of a distal protection device has been shown to improve the outcomes in SVG interventions. We describe an intervention done in an unexpected 'Y' SVG which required dual distal protection with Filterwires placed in both limbs of the diseased graft and which was performed via a 6 Fr guide catheter.  相似文献   
40.
We investigated the spatial resolution requirement and the effect of unsharp-mask filtering on the detectability of subtle microcalcifications in digital mammography. Digital images were obtained by digitizing conventional screen-film mammograms with a 0.1 X 0.1 mm2 pixel size, processed with unsharp masking, and then reconstituted on film with a Fuji image processing/simulation system (Fuji Photo Film Co., Tokyo, Japan). Twenty normal cases and 12 cases with subtle microcalcifications were included. Observer performance experiments were conducted to assess the detectability of subtle microcalcifications in the conventional, the unprocessed digital, and the unsharp-masked mammograms. The observer response data were evaluated using receiver operating characteristic (ROC) and LROC (ROC with localization) analyses. Our results indicate that digital mammograms obtained with 0.1 X 0.1 mm2 pixels provide lower detectability than the conventional screen-film mammograms. The detectability of microcalcifications in the digital mammograms is improved by unsharp-mask filtering; the processed mammograms still provide lower accuracy than the conventional mammograms, however, chiefly because of increased false-positive detection rates for the processed images at each subjective confidence level. Viewing unprocessed digital and unsharp-masked images in pairs resulted in approximately the same detectability as that obtained with the unsharp-masked images alone. However, this result may be influenced by the fact that the same limited viewing time was necessarily divided between the two images.  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