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   18734篇
  免费   1241篇
  国内免费   102篇
耳鼻咽喉   170篇
儿科学   382篇
妇产科学   293篇
基础医学   2615篇
口腔科学   192篇
临床医学   1716篇
内科学   4594篇
皮肤病学   312篇
神经病学   1878篇
特种医学   820篇
外国民族医学   1篇
外科学   3185篇
综合类   47篇
一般理论   5篇
预防医学   919篇
眼科学   190篇
药学   1231篇
中国医学   32篇
肿瘤学   1495篇
  2023年   122篇
  2022年   172篇
  2021年   571篇
  2020年   283篇
  2019年   549篇
  2018年   629篇
  2017年   435篇
  2016年   427篇
  2015年   528篇
  2014年   805篇
  2013年   939篇
  2012年   1510篇
  2011年   1582篇
  2010年   850篇
  2009年   828篇
  2008年   1278篇
  2007年   1198篇
  2006年   1196篇
  2005年   1098篇
  2004年   1033篇
  2003年   876篇
  2002年   869篇
  2001年   192篇
  2000年   134篇
  1999年   171篇
  1998年   168篇
  1997年   161篇
  1996年   117篇
  1995年   104篇
  1994年   89篇
  1993年   67篇
  1992年   105篇
  1991年   83篇
  1990年   88篇
  1989年   107篇
  1988年   90篇
  1987年   65篇
  1986年   66篇
  1985年   50篇
  1984年   43篇
  1983年   34篇
  1982年   33篇
  1981年   19篇
  1977年   19篇
  1975年   25篇
  1974年   24篇
  1972年   23篇
  1970年   28篇
  1969年   24篇
  1968年   18篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
21.
22.
The potential gravity of post-operative vascular infection makes early diagnosis essential. We report a case where this diagnosis was made on CT findings alone, in the absence of any other signs of infection. Rapid intervention led to complete cure. Beyond the immediate post-operative period, the presence of gas on the CT scan is rare but pathognomonic in the absence of a cutaneous fistula. The presence of this sign is therefore sufficient to indicate that reintervention is mandatory.  相似文献   
23.
Piribedil is a non-ergot D2/D3 agonist with a significant antagonist action on alpha2A and alpha2C adrenergic receptor subtypes. This double-blind placebo-controlled study was undertaken to confirm the efficacy of 150 mg/day piribedil po in improving motor symptoms of idiopathic Parkinson's disease (PD) in nonfluctuating patients insufficiently controlled by a stable daily dose of levodopa (L-dopa). Efficacy was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) III score as primary criterion over 4 months. A second comparison was planned at 6 months, after possible adjustment of L-dopa. At 4 months, the rate of response, defined as a 30% decrease from baseline on UPDRS III score, was significantly greater with piribedil compared with placebo (56.4% vs. 37.7%; P = 0.040). At 6 months, the better efficacy of piribedil was maintained (61.8% of responders vs. 39.6% on placebo; P = 0.020). The difference between groups on UPDRS III change from baseline reached statistical significance only at 6 months: -10.0 points in the piribedil group vs. -6.7 points in the placebo group (P = 0.037). Secondary end-points were not significantly different. The most frequently reported adverse events were gastrointestinal symptoms (27 of 61 patients in the piribedil group vs. 13 of 54 patients in the placebo group). In conclusion, a 6-month oral administration of 150 mg/day piribedil in combination with L-dopa is well tolerated, except for minor gastrointestinal symptoms at the beginning of the treatment and significantly improves motor symptoms compared with placebo in PD nonfluctuating patients.  相似文献   
24.
25.
26.
Assessment of disease activity in rheumatoid arthritis with (18)F-FDG PET.   总被引:5,自引:0,他引:5  
The aim of this study was to assess synovitis by (18)F-FDG PET in an individual joint analysis and in a global analysis of rheumatoid arthritis (RA) disease activity and to compare (18)F-FDG PET parameters with clinical, biologic, and sonographic (US) rheumatoid parameters. METHODS: Three hundred fifty-six joints were assessed in 21 patients with active RA: the knees in all subjects and either wrists as well as metacarpophalangeal and proximal interphalangeal joints in 13 patients, or ankles and the first metatarsophalangeal joints in the remaining 8 patients. PET analysis consisted of a visual identification of (18)F-FDG uptake in the synovium and measurements of standardized uptake values (SUVs). Independent assessors performed the clinical and US examinations. RESULTS: PET positivity was found in 63% of joints, whereas 75%, 79%, and 56% were positive for swelling, tenderness, and US analysis, respectively. Both the rate of PET-positive joints and the SUV increased with the number of positive parameters present (swelling, tenderness, US positivity) and with the synovial thickness. The mean SUV was significantly higher in joints where a power Doppler signal was found. In a global PET analysis, the number of PET-positive joints and the cumulative SUV were significantly correlated with the swollen and tender joint counts, the patient and physician global assessments, the erythrocyte sedimentation rate and C-reactive protein serum levels, the disease activity score and the simplified disease activity index, the number of US-positive joints, and the cumulative synovial thickness. CONCLUSION: (18)F-FDG PET is a unique imaging technique that can assess the metabolic activity of synovitis and measure the disease activity in RA.  相似文献   
27.

Background  

Hypophosphatasia (HP) is characterized by a genetic defect in the tissue-nonspecific alkaline phosphatase (TNSALP) gene and predominantly an autosomal recessive trait. HP patients suffer from reduced bone mineralization. Biochemically, elevated concentrations of substrates of TNSALP, including pyridoxal-5'-phosphate and inorganic pyrophosphate occur in serum, tissues and urine. The latter has been associated with chronic inflammation and hyperprostaglandinism.  相似文献   
28.
Pericardial puncture is the percutaneous insertion of a needle into the pericardial space to drain a pathological pericardial effusion. The challenge for the operating surgeon is to reach percutaneously a target zone in the vicinity of the mobile heart, in a soft-tissue environment. The surgeon's ability to accomplish this depends on his own mental picture of the effusion. CASPER is a navigation software using an optical localizer which assists the surgeon by enhancing the representation of the effusion and guiding the needle's progress. Using a localized and calibrated echographic probe, the surgeon acquires a set of images in the region of interest. This zone is then manually segmented on each image, a common zone is computed, and the surgeon defines a trajectory for the needle. During the puncture procedure, the surgeon follows the position of the localized needle on a computer monitor. After initial validation on an experimental phantom, a feasibility study was performed using canine and porcine models. The optical localization device was changed from an Optotrak to a Polaris device for easier use in the clinical setting. Prior to clinical application, various tests were performed concerning the mobility of the thoracic cage, the reproducibility of the thoracic position over several apneas, and the stability of anatomic structures relative to the thoracic cage. Finally, a first clinical application was successfully performed using this system. The present paper reports on these last two stages.  相似文献   
29.
30.
Several common postdischarge symptoms, such as sleep disorders, headache, drowsiness or general malaise, evoke disturbances of circadian rhythms due to jet lag (ie crossing time zones) or shift work rotation. Considering that general anesthesia is associated with numerous effects on the central nervous system, we hypothesized that it may also act on the circadian timing system. We first determined the effects of the circadian timing on general anesthesia. We observed that identical doses of propofol showed marked circadian fluctuations in duration of effects, with a peak at the middle of the resting period (ie 7 h after lights on). Then, we examined the effects of general anesthesia on circadian timing, by analysing stable free-running circadian rhythms (ie in constant environmental conditions), an experimental approach used widely in circadian biology. Free-running rats were housed in constant darkness and temperature to assess possible phase-shifting effects of propofol anesthesia according to the time of the day. When administered around (+/-2 h) the daily rest/activity transition point, a 30-min propofol anesthesia induced a 1-h phase advance in the free-running rest-activity rhythm, while anesthesia had no significant resetting effect at other times of the day. Anesthesia-induced hypothermia was not correlated with the phase-shifting effects of propofol anesthesia. From our results, anesthesia itself can reset circadian timing, and acts as a synchronizing cue for the circadian clock.  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