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   35986篇
  免费   2206篇
  国内免费   162篇
耳鼻咽喉   508篇
儿科学   836篇
妇产科学   648篇
基础医学   4317篇
口腔科学   662篇
临床医学   3488篇
内科学   8537篇
皮肤病学   425篇
神经病学   3397篇
特种医学   1438篇
外国民族医学   2篇
外科学   6266篇
综合类   229篇
一般理论   18篇
预防医学   2155篇
眼科学   475篇
药学   2056篇
中国医学   45篇
肿瘤学   2852篇
  2024年   26篇
  2023年   209篇
  2022年   410篇
  2021年   910篇
  2020年   558篇
  2019年   905篇
  2018年   1119篇
  2017年   765篇
  2016年   777篇
  2015年   931篇
  2014年   1379篇
  2013年   1849篇
  2012年   2739篇
  2011年   2926篇
  2010年   1662篇
  2009年   1601篇
  2008年   2533篇
  2007年   2659篇
  2006年   2481篇
  2005年   2396篇
  2004年   2161篇
  2003年   2021篇
  2002年   1817篇
  2001年   274篇
  2000年   174篇
  1999年   240篇
  1998年   398篇
  1997年   312篇
  1996年   225篇
  1995年   224篇
  1994年   183篇
  1993年   177篇
  1992年   98篇
  1991年   112篇
  1990年   88篇
  1989年   78篇
  1988年   60篇
  1987年   58篇
  1986年   59篇
  1985年   69篇
  1984年   87篇
  1983年   88篇
  1982年   84篇
  1981年   80篇
  1980年   66篇
  1979年   38篇
  1978年   37篇
  1977年   26篇
  1975年   24篇
  1974年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
In cystic fibrosis (CF), absorption of tacrolimus through the gastrointestinal tract may be impaired due to fat malabsorption. The aim of this pilot study was to compare tacrolimus pharmacokinetics and inter- and intrasubject variability of exposure in stable lung transplant recipients with and without CF, and to determine the best single-time predictors of exposure. The study included 11 lung transplant recipients with CF and 11 without CF who received tacrolimus twice daily. Blood samples were obtained predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 h postdose on 3 separate days within 1 week. Tacrolimus pharmacokinetics and inter- and intrasubject variability of exposure were similar in the two groups, though exposure-per-milligram-dose was approximately 50% lower in CF patients. Tacrolimus trough concentration did not accurately predict the area under the concentration curve (AUC(0-12)), but the concentration measured 3 h postdose (C(3)) was tightly correlated with the AUC(0-12) in both CF (r(2)= 0.86) and non-CF (r(2)= 0.92) patients. In summary, patients with CF have a higher tacrolimus oral clearance, but nonsignificant differences in short-term inter- and intrasubject variability of exposure compared to patients without CF. C(3) is tightly correlated with AUC(0-12) in lung transplant recipients with and without CF.  相似文献   
52.
The combination of small-animal PET and MRI data provides quantitative in vivo insights into cardiac pathophysiology, integrating information on biology and morphology. We sought to determine the feasibility of PET and MRI for the quantification of ischemic injury in the rat model. METHODS: Fourteen healthy male Wistar rats were studied with 18F-FDG PET and cine MRI. Myocardial viability was determined in a transmural myocardial infarction model in 12 additional rats, using 18F-FDG PET and delayed-enhancement MRI with gadolinium-diethylenetriaminepentaacetic acid. All PET was acquired with a dedicated small-animal PET system. MRI was performed on a 1.5-T clinical tomograph with a dedicated small-animal electrocardiographic triggering device and a small surface coil. RESULTS: In normal rats, 18F-FDG uptake was homogeneous throughout the left ventricle. The lowest mean uptake of the 18F-FDG was found in the apical regions (79% +/- 6.0% of maximum) and the highest uptake was in the anterior wall (93% +/- 4.3 % of maximum). Myocardial infarct size as determined by histology correlated well with defects of glucose metabolism obtained with 18F-FDG PET (r = 0.89) and also with delayed-enhancement MRI (r = 0.91). Left ventricular ejection fraction in normal rats measured by cine MRI was 57% +/- 5.4% and decreased to 38% +/- 12.9% (P < 0.001) in the myocardial infarction model. CONCLUSION: Integrating information from small-animal PET and clinical MRI instrumentation allows for the quantitative assessment of cardiac function and infarct size in the rat model. The MRI measurements of scar can be complemented by metabolic imaging, addressing the extent and severity of ischemic injury and providing endpoints for therapeutic interventions.  相似文献   
53.
We performed noninvasive coronary angiography using 64-slicecomputed tomography (CT) in a 65-year-old man with onset ofatypical angina pectoris and detected a chronic  相似文献   
54.
55.
56.
In the course of 1 year at a tertiary cancer center, 3 patients (2 men; 1 woman; age 51-75 years) were seen in neurological consultation (1.5% of all consultations). Clinical course in all patients was of a progressive neurologic disorder not consistent with either a primary or secondary malignancy. Magnetic resonance (MR) imaging was most informative with respect to diagnosis and subsequent management. Brain biopsy was performed in all patients to assist in both diagnosis and prognostication. All patients were determined to have progressive multifocal leukoencephalopathy (PML) by brain biopsy.  相似文献   
57.
58.
59.
60.
F Sris  I Marc 《Thorax》1994,49(6):562-566
BACKGROUND--A study was performed to evaluate the effect of discontinuation of nasal continuous positive airway pressure (NCPAP) treatment on snoring characteristics. METHODS--Eighteen non-apnoeic snoring subjects were randomly allocated to either a no treatment control group or an NCPAP treatment group. The control group was studied twice (baseline and day 30 of follow up). In the NCPAP group the level of NCPAP that abolished snoring was determined and part abolished snoring was determined and patients were placed on NCPAP every night for one month. A sleep study was performed on the first night without NCPAP after completing 30 days of treatment (follow up 1). A fourth polysomnographic study was performed 8-10 days after NCPAP was stopped (follow up 2) in six subjects. RESULTS--In both groups total sleep time (TST) and sleep architecture remained unchanged at the different visits. Baseline snoring characteristics in the two groups were similar. In the control group the mean (SE) number of snoring episodes/hour of sleep (snoring index) and the percentage of TST > 60 decibels (dB) were 380 (36)/h and 11.1 (2.0)% TST respectively at baseline, and was unchanged at follow up. In the NCPAP group the snoring index decreased from 387 (50)/h to 320 (57)/h after NCPAP therapy, but the % TSTS > 60 dB decreased from 10.3 (1.8)% to 7.4 (1.5)%. The snoring index and intensity returned to baseline values at follow up 2 (374 (74)/h, 9.8 (2.1)% TST). Changes in snoring characteristics could not be explained by changes in body position between the different sleep studies. CONCLUSIONS--NCPAP improves snoring but this effect is lost soon after stopping treatment.  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