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   4335篇
  免费   253篇
  国内免费   51篇
耳鼻咽喉   53篇
儿科学   70篇
妇产科学   68篇
基础医学   563篇
口腔科学   76篇
临床医学   383篇
内科学   1141篇
皮肤病学   92篇
神经病学   390篇
特种医学   178篇
外科学   670篇
综合类   25篇
一般理论   5篇
预防医学   221篇
眼科学   57篇
药学   243篇
中国医学   8篇
肿瘤学   396篇
  2024年   10篇
  2023年   48篇
  2022年   90篇
  2021年   173篇
  2020年   95篇
  2019年   141篇
  2018年   154篇
  2017年   114篇
  2016年   135篇
  2015年   152篇
  2014年   165篇
  2013年   258篇
  2012年   423篇
  2011年   355篇
  2010年   203篇
  2009年   162篇
  2008年   305篇
  2007年   260篇
  2006年   253篇
  2005年   248篇
  2004年   205篇
  2003年   193篇
  2002年   172篇
  2001年   22篇
  2000年   22篇
  1999年   39篇
  1998年   32篇
  1997年   14篇
  1996年   11篇
  1995年   10篇
  1994年   20篇
  1993年   9篇
  1992年   14篇
  1991年   7篇
  1990年   11篇
  1989年   16篇
  1988年   6篇
  1987年   8篇
  1986年   11篇
  1985年   12篇
  1984年   9篇
  1983年   9篇
  1982年   4篇
  1981年   5篇
  1980年   5篇
  1979年   6篇
  1977年   3篇
  1974年   3篇
  1973年   3篇
  1972年   3篇
排序方式: 共有4639条查询结果,搜索用时 0 毫秒
71.
AIM OF THE STUDY: To compare clinical and ultrasound (US) changes induced in cold thyroid nodules by US-guided percutaneous laser ablation (PLA) versus follow-up or levothyroxine (LT4) suppressive therapy. METHODS: 62 patients randomly assigned to a single PLA (Group 1), LT4 (Group 2), or follow-up (Group 3). Entry criteria: euthyroid patients with a solid thyroid nodule >5 mL and benign cytological findings. TREATMENT: Group 1: PLA was performed with a 1.064 mum neodymium yttrium-aluminum-garnet laser with output power of 3 W for 10 minutes; Group 2: the LT4 dose was adjusted to induce thyrotropin suppression; Group 3: no treatment. RESULTS: In Group 1 a significant nodule reduction was found 6 and 12 months after PLA (delta volume: -42.7 +/- 13.6%; p = 0.001). A reduction >50% was found in 33.3% of cases. In Group 2 a nonsignificant nodule shrinkage was observed. A nonsignificant volume increase was observed in Group 3. Improvement of local symptoms was registered in 81.2% of patients in Group 1 vs. 13.3% in Group 2 and 0.0% in Group 3 ( p = 0.001). No complications were noted. CONCLUSIONS: A single PLA induced significant volume reduction and improvement of local symptoms. PLA was more effective than LT4. Follow-up was associated with nodule growth and progression of local symptoms. PLA should be considered a potential mini-invasive alternative to surgery in symptomatic patients with benign cold thyroid nodules.  相似文献   
72.
‘Additive manufacturing’ (AM) refers to a class of manufacturing processes based on the building of a solid object from three‐dimensional (3D) model data by joining materials, usually layer upon layer. Among the vast array of techniques developed for the production of tissue‐engineering (TE) scaffolds, AM techniques are gaining great interest for their suitability in achieving complex shapes and microstructures with a high degree of automation, good accuracy and reproducibility. In addition, the possibility of rapidly producing tissue‐engineered constructs meeting patient's specific requirements, in terms of tissue defect size and geometry as well as autologous biological features, makes them a powerful way of enhancing clinical routine procedures. This paper gives an extensive overview of different AM techniques classes (i.e. stereolithography, selective laser sintering, 3D printing, melt–extrusion‐based techniques, solution/slurry extrusion‐based techniques, and tissue and organ printing) employed for the development of tissue‐engineered constructs made of different materials (i.e. polymeric, ceramic and composite, alone or in combination with bioactive agents), by highlighting their principles and technological solutions. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
73.
OBJECTIVE: Tuberculosis (TB) in patients with rheumatoid arthritis (RA) undergoing treatment with anti-tumor necrosis factor (TNF) agents is commonly the result of reactivation of latent TB infection (LTBI); detection and treatment of LTBI is essential before treatment with anti-TNF agents. We reported previously that the tuberculin skin test (TST) is inaccurate for diagnosis of LTBI in patients with RA. Here, we compare the prevalence of LTBI in RA patients and matched controls according to positive TST and QuantiFeron-TB Gold In-Tube version (QFT) results and determine their agreement. METHODS: A cross-sectional study of 101 RA patients and 93 controls was conducted in Lima, Perú, where the prevalence of LTBI in the general population has been estimated to be 68%. Blood was drawn for QFT assay followed by TST using 2-TU of RT 23 purified protein derivative. TST was deemed positive at >or= 5 mm for RA patients and >or= 10 mm for controls. RESULTS: There were no significant differences between RA patients and controls for age, sex, bacillus Calmette-Guérin vaccination, or history of or contact with TB. 88% of patients had active RA disease and 2 (1.9%) patients had indeterminate QFT results. The number of subjects testing positive with the QuantiFeron assay was comparable between patients and controls (44.6% vs 59.1%, respectively), whereas the TST detected significantly less LTBI among RA patients (26.7%) than controls (65.6%). Thus, the rate of LTBI in RA patients represented 75% and 41% of the rate in their controls using QFT or TST, respectively (p = 0.008). Poor agreement between TST and QFT was seen in RA patients, but in controls, good agreement was observed between these tests. CONCLUSION: In a TB-endemic population, the QuantiFeron-TB Gold In-Tube assay seemed to be a more accurate test for detection of LTBI in RA patients compared with the TST, and may potentially improve the targeting of prophylactic therapy before treatment with anti-TNF agents.  相似文献   
74.
Purpose: To describe the development of BrightBrainer? integrative cognitive rehabilitation system and determine clinical feasibility with nursing home-bound dementia patients. Method: BrightBrainer cognitive rehabilitation simulations were first played uni-manually, then bimanually. Participants sat in front of a laptop and interacted through a game controller that measured hand movements in 3D, as well as flexion of both index fingers. Interactive serious games were designed to improve basic and complex attention (concentration, short-term memory, dual tasking), memory recall, executive functioning and emotional well-being. Individual simulations adapted automatically to each participant’s level of motor functioning. The system underwent feasibility trials spanning 16 sessions over 8 weeks. Participants were evaluated pre- and post-intervention, using standardized neuropsychological measures. Computerized measures of movement repetitions and task performance were stored on a remote server. Results: Group analysis for 10 participants showed statistically significant improvement in decision making (p?p?p?p?p?Conclusions: Preliminary findings demonstrate utility within an advanced dementia population, suggesting that it will be beneficial to evaluate BrightBrainer through controlled clinical trials and to investigate its application in other clinical populations.
  • Implications for Rehabilitation
  • It is possible to improve cognitive function in older low-functioning patients. Integrative rehabilitation through games combining cognitive (memory, focusing, executive function) and physical (bimanual whole arm movement, grasping, task sequencing) elements is enjoyable for this population.

  • The severity of depression in these elderly can be reduced through virtual reality bimanual games.

  • The number of upper extremity active repetitions performed in the process of solving cognitive problems with the BrightBrainer? system is 600. This number is 18 times (1875%) larger than those observed by other researchers in conventional physical or occupational rehabilitation sessions.

  相似文献   
75.
76.
Cardiac angiosarcomas are malignant tumors that almost invariably have a short and fatal evolution. The therapeutic approach includes surgery, chemotherapy, and radiation therapy, alone or in combination. Heart transplantation is an attractive option in nonresectable tumors, even though the current experience is still limited. However, in most patients, the diagnosis is still established late, and survival is only slightly altered by the proposed treatments, mainly due to previously existing and undetected metastases. We report a case that illustrates the therapeutic dilemma faced with this neoplasia, and we discuss the case based on a literature review.  相似文献   
77.
78.
79.

Background

Contrast-enhanced intra-operative ultrasound (CE-IOUS) for colorectal liver metastases (CLMs) has become a part of clinical practice. Whether it should be selectively or routinely applied remains unclear. The aim of this study was to define criteria for the use of CE-IOUS.

Methods

One-hundred and twenty-seven patients underwent a hepatectomy for CLMs using IOUS and CE-IOUS. All patients underwent computed tomography (CT) and/or magnetic resonance imaging (MRI) within 2 weeks prior to surgery. The reference was histology, and imaging at 6 months after surgery. Univariate and multivariate analyses were performed. Statistical significance was set at P = 0.05.

Results

Using IOUS an additional 172 lesions in 51 patients were found. CE-IOUS found 14 additional lesions in 6 patients. Seventy-eight CLMs in 38 patients appeared within 6 months after surgery. The sensitivity, specificity, positive- and negative-predictive value were 63%, 98%, 100% and 27% for pre-operative imaging, 87%, 100%, 100% and 52% for IOUS, and 89%, 100%, 100% and 56% for IOUS+CE-IOUS, respectively. CE-IOUS allowed better tumour margin definition in 23 patients (18%), thus assisting resection. Analyses indicated that the presence of multiple (P = 0.014), and isoechoic CLMs (P = 0.049) were independently correlated with new findings at CE-IOUS.

Conclusions

Compared with IOUS, CE-IOUS improved detection and resection guidance. These additions are significant and demand its use in cases with multiple and isoechoic CLMs.  相似文献   
80.
AIM:To evaluate the most cost-effectiveness strategy for preventing variceal growth and bleeding in patients with cirrhosis and small esophageal varices.METHODS:A stochastic analysis based on decision trees was performed to compare the cost-effectiveness of beta-blockers therapy starting from a diagnosis of small varices(Strategy 1)with that of endoscopic surveillance followed by beta-blockers treatment when large varices are demonstrated(Strategy 2),for preventing variceal growth,bleeding and death in patients with cirrhosis and small esophageal varices.The basic nodes of the tree were gastrointestinal endoscopy,inpatient admission and treatment for bleeding,as required.All estimates were performed using a Monte Carlo microsimulation technique,consisting in simulating observations from known probability distributions depicted in the model.Eight-hundred-thousand simulations were performed to obtain the final estimates.All estimates were then subjected to Monte Carlo Probabilistic sensitivity analysis,to assess the impact of the variability of such estimates on the outcome distributions.RESULTS:The event rate(considered as progression of varices or bleeding or death)in Strategy 1[24.09%(95%CI:14.89%-33.29%)]was significantly lower than in Strategy 2[60.00%(95%CI:48.91%-71.08%)].The mean cost(up to the first event)associated with Strategy 1[823£(95%CI:106£-2036£)]was not significantly different from that of Strategy 2[799£(95%CI:0£-3498£)].The cost-effectiveness ratio with respect to this endpoint was equal to 50.26£(95%CI:-504.37£-604.89£)per event avoided over the four-year follow-up.When bleeding episodes/deaths in subjects whose varices had grown were included,the mean cost associated with Strategy 1 was 1028£(95%CI:122£-2581£),while 1699£(95%CI:171£-4674£)in Strategy 2.CONCLUSION:Beta-blocker therapy turn out to be more effective and less expensive than endoscopic surveillance for primary prophylaxis of bleeding in patients with cirrhosis and small varices.  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