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   14811篇
  免费   760篇
  国内免费   40篇
耳鼻咽喉   272篇
儿科学   345篇
妇产科学   292篇
基础医学   2687篇
口腔科学   328篇
临床医学   1370篇
内科学   2910篇
皮肤病学   312篇
神经病学   1153篇
特种医学   826篇
外科学   1825篇
综合类   102篇
一般理论   1篇
预防医学   812篇
眼科学   387篇
药学   1254篇
中国医学   20篇
肿瘤学   715篇
  2022年   95篇
  2021年   192篇
  2020年   136篇
  2019年   172篇
  2018年   200篇
  2017年   139篇
  2016年   231篇
  2015年   238篇
  2014年   327篇
  2013年   491篇
  2012年   737篇
  2011年   793篇
  2010年   467篇
  2009年   461篇
  2008年   766篇
  2007年   842篇
  2006年   840篇
  2005年   786篇
  2004年   752篇
  2003年   729篇
  2002年   686篇
  2001年   266篇
  2000年   251篇
  1999年   267篇
  1998年   182篇
  1997年   176篇
  1996年   140篇
  1995年   108篇
  1994年   110篇
  1993年   90篇
  1992年   136篇
  1991年   127篇
  1990年   114篇
  1989年   101篇
  1988年   92篇
  1987年   77篇
  1986年   91篇
  1985年   81篇
  1933年   85篇
  1932年   84篇
  1931年   91篇
  1930年   104篇
  1929年   88篇
  1928年   87篇
  1927年   83篇
  1926年   85篇
  1925年   82篇
  1924年   88篇
  1923年   86篇
  1922年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Creatine (Cr) is a substrate for adenosine triphosphate synthesis, and it is the most used dietary supplement among professional and recreative athletes and sportsmen. Creatine supplementation may increase allergic airway response, but the cellular and molecular mechanisms are unknown. We used murine model of OVA‐induced chronic asthma and showed that Cr supplementation increased total proteins, ATP level, lymphocytes, macrophages, and IL‐5 levels in BALF, as well as IL‐5 in the supernatant of re‐stimulated mediastinal lymph nodes. IL‐5 and IL‐13 expression by epithelial cells and by peribronchial leukocytes were increased by Cr. Cr augmented the expression of P2 × 7 receptor by peribronchial leukocytes and by epithelial cells, and increased the accumulation of eosinophils in peribronchial space and of collagen fibers in airway wall. In human cells, while Cr induced a release of ATP, IL‐6, and IL‐8 from BEAS‐2B cells, whole blood cells, such as eosinophils, and CD4+ T cells, P2 × 7 receptor inhibitor (A740003) reduced such effects, as denoted by reduced levels of ATP, IL‐6, and IL‐8. Therefore, Cr supplementation worsened asthma pathology due to activation of airway epithelial cells and peribronchial leukocytes, involving purinergic signaling.  相似文献   
32.
33.
Purpose/Aim of the study: Chlorhexidine and polyhexanide are frequently used antiseptics in clinical practice and have a broad antimicrobial range. Both antiseptics are helpful medical agents for septic wound treatment with a high potential for defeating joint infections. Their effect on human osteoblasts has, so far, not been sufficiently evaluated. The aim of this study was to investigate the activating potential of polyhexanide and chlorhexidine on inflammatory cytokines/chemokines in human osteoblasts in vitro. Materials and Methods: Human osteoblasts were isolated and cultivated in vitro and then treated separately with 0.1% and 2% chlorhexidine and 0.04% polyhexanide as commonly applied concentrations in clinical practice. Detection of cell structure and cell morphology was performed by light microscopic inspection. Cytokine and chemokine secretion was determined by using a multiplex suspension array. Results: Cell shrinking, defective cell membrane, and the loss of cell adhesion indicated cell damage of human osteoblasts after treatment with both antiseptics was evaluated by using light microscopy. Polyhexanide, but not chlorhexidine, caused human osteoblasts to secrete various interleukins (1β, 6, and 7), interferon γ, tumor necrosis factor α, vascular endothelial growth factor, eotaxin, fibroblast growth factor basic, and granulocyte macrophage colony-stimulating factor as quantified by multiplex suspension array. Conclusions: Both antiseptics induced morphological cell damage at an optimum exposure between 1 and 10 min. But only polyhexanide mediated a pronounced secretion of inflammatory cytokines and chemokines in human osteoblasts. Therefore, we recommend a preferred usage of chlorhexidine in septic surgery to avoid the induction of an inflammatory reaction.  相似文献   
34.
35.
Background and purpose — Optimal treatment for distal radius fractures remains controversial, with a significant number of fractures resulting in complications and long-term morbidity. We investigated patient injury claims related to distal radius fractures to detect the critical steps in the treatment leading to avoidable adverse events

Patients and methods — We analyzed all compensated patient injury claims in Finland between 2007 and 2011. Claims were collected from the Patient Insurance Center’s (PIC) nationwide claim register. Patients of all ages were included. Each claim decision, original patient records, and radiographs related to treatment were reviewed.

Results — During the study period, the PIC received 584 claims regarding distal radius fractures, of which 208 (36%) were compensated. Pain and impaired wrist function were the most common subjective reasons to file claims among compensated patients. In 66/208 patients, more than 1 adverse event leading to patient injury was detected. The detected adverse events could be divided into 3 main groups: diagnostic errors (36%, n = 103), decision/planning errors (30%, n = 87), and insufficient technical execution (32%, n = 91). Issues related to malalignment were the main concerns in each group. Diagnostic errors were often related to incorrect assessment of the fracture (re)displacement (75%, n = 78). All of the decision-making errors concerned physicians’ decisions to accept unsatisfactory fracture alignment. The most common technical error was insufficient reduction (29%, n = 26).

Interpretation — We identified avoidable adverse events behind patient injuries related to distal radius fracture treatment. This study will help physicians to recognize the critical steps in the treatment of this common fracture and enhance patient safety.  相似文献   

36.
37.
Cherubism (OMIM : 118400) is an autosomal dominant disorder affecting mainly facial bones leading to disfigurement of face needing medical and surgical attention besides impairing the self esteem of person. At present, there is no medical cure and there is limited indication for surgery in such cases. So, correct diagnosis is of paramount importance to both treating physician and family. Here, the authors report a family with two affected members (mother and daughter) who were tested positive for a known pathogenic mutation and thus offered timely treatment and adequate genetic counseling.  相似文献   
38.
Electrocardiograms (ECGs) made with Mason-Likar electrode configuration (ML-ECGs) show well-known differences from standard 12-lead ECGs (Std-ECGs). We recorded, simultaneously, Std-ECGs and ML-ECGs in 180 subjects. Using these ECGs, 8 × 8 individual and general conversion matrices were created by linear regression, and standard ECGs were reconstructed from ML-ECGs using these matrices. The performance of the matrices was assessed by the root mean square differences between the original Std-ECGs and the reconstructed standard ECGs, by the differences in major ECG parameters, and by comparison of computer-generated diagnostic statements. As a result, we conclude that, based on the root mean square differences, reconstructions with 8 × 8 individual matrices perform significantly better than reconstructions with the group matrix and perform equally well with respect to the calculation of major electrocardiographic parameters, which gives an improved reliability of the QRS frontal axis and the maximal QRS and T amplitudes. Both types of matrices were able to reverse the underdiagnosis of inferior myocardial infarctions and the erroneous statements about the QRS frontal axis that arose in the ECGs that were made by using the Mason-Likar electrode positions.  相似文献   
39.
Disease progression in cystic fibrosis (CF) leads to muscle wasting and loss of muscle function. The aim of this prospective pilot study was to evaluate the effects of whole body vibration (WBV) on muscle function in adult patients with CF. Ten patients (three males; seven females) of the CF Center Cologne, Germany, have completed the 3-month study (age: 24-47 years; forced expiratory volume in 1 s (FEV1) 17-109% predicted (49+/-29) and body mass index (BMI) 16.6-24.4 kg/m2 (19.3+/-2.5). WBV was provided by a vibration platform (Galileo 2000). The patients were standing in an upright position receiving vertical vibration of frequencies between 20 and 25 Hz. The vibration exercise evokes muscle contractions via stretch reflexes improving muscular activity. The training schedule consisted of three 3-min sessions twice a day, 5 days per week for 3 months. Every 4 weeks the following tests were carried out: FEV1, forced vital capacity (FVC), BMI, chair-rising test (CRT), one-leg and two-leg jump test as well as maximal isometric grip force. The study has been approved by the local ethics committee. After 3 months of WBV all parameters in the CRT significantly improved: chair-rising time (P=0.03), maximal force (P=0.02), maximal power (P=0.01) as well as velocity (P=0.02). The peak jump force (P=0.02) and velocity (P=0.01) of the two-leg jump significantly improved. Parameters in the one-leg jump as well as maximal isometric grip force showed no significant improvement. Weight and BMI showed a slightly positive trend whereas FEV1 and FVC did not significantly change. Any change in mechanographic parameters did not correlate with FEV1 or FVC in this study. These results demonstrate that WBV can improve muscle function in CF patients.  相似文献   
40.

Objectives

To compare the diagnostic performance of diffusion-weighted MR imaging (DWI) with multi-slice CT (MS-CT) in the detection and classification of focal liver lesions in patients with colorectal cancer.

Methods

In a retrospective study 68 patients who underwent DWI at 1.5 T (b-values of 50, 300 and 600 s/mm2) and contrast-enhanced MS-CT were analysed by two radiologists blinded to the clinical results. Imaging results were correlated with intraoperative surgical and ultrasound findings (n = 24), imaging follow-up or PET (n = 44). Sensitivity of DWI and MS-CT in detection of focal liver lesions was compared on a per-lesion and a per-segment basis. Receiver operator-characteristic (ROC) curves to determine the diagnostic performance and the sensitivities of correctly identifying liver metastases on a segmental base were calculated.

Results

For lesion detection, DWI was significantly superior to MS-CT both on a per-lesion (difference in sensitivities for reader 1 and 2 22.65% and 19.06%, p < 0.0001) and a per-segment basis (16.86% and 11.76%, p < 0.0001). Especially lesions smaller than 10 mm were better detected with DWI compared to MS-CT (difference 41.10% and 29.45%, p < 0.0001). ROC-analysis showed superiority for lesions classification (p < 0.0001) of DWI (AUC: 0.949 and 0.951) as compared to MS-CT (AUC: 0.879 and 0.892, p < 0.0001 and p = 0.005). DWI was able to filter out metastatic segments with a higher sensitivity (88.2 and 86.5%) compared to MS-CT (68.0 and 67.4%, p < 0.0001 and p = 0.005, respectively).

Conclusion

Compared to MS-CT DWI is both more sensitive in the detection of liver lesions and more accurate in determining the extent of metastatic disease in patients with colorectal cancer and therefore might help to optimize therapeutic management in those patients.  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