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   795篇
  免费   49篇
  国内免费   17篇
耳鼻咽喉   10篇
儿科学   81篇
妇产科学   40篇
基础医学   102篇
口腔科学   15篇
临床医学   52篇
内科学   169篇
皮肤病学   25篇
神经病学   30篇
特种医学   54篇
外科学   88篇
综合类   18篇
预防医学   45篇
眼科学   7篇
药学   30篇
中国医学   2篇
肿瘤学   93篇
  2023年   8篇
  2022年   8篇
  2021年   9篇
  2020年   16篇
  2019年   11篇
  2018年   19篇
  2017年   19篇
  2016年   13篇
  2015年   8篇
  2014年   19篇
  2013年   43篇
  2012年   42篇
  2011年   32篇
  2010年   23篇
  2009年   29篇
  2008年   27篇
  2007年   19篇
  2006年   37篇
  2005年   42篇
  2004年   28篇
  2003年   33篇
  2002年   22篇
  2001年   21篇
  2000年   19篇
  1999年   10篇
  1998年   24篇
  1997年   24篇
  1996年   25篇
  1995年   22篇
  1994年   17篇
  1993年   17篇
  1992年   12篇
  1991年   12篇
  1990年   6篇
  1989年   20篇
  1988年   14篇
  1987年   13篇
  1986年   10篇
  1985年   9篇
  1983年   11篇
  1982年   4篇
  1980年   6篇
  1979年   4篇
  1978年   4篇
  1977年   6篇
  1976年   5篇
  1975年   6篇
  1970年   6篇
  1967年   3篇
  1966年   3篇
排序方式: 共有861条查询结果,搜索用时 15 毫秒
851.
Plinia cauliflora (Mart.) Kausel, widespread in South America, has edible fruits, and its bark is commonly used against diarrhea and other disorders, on account of its astringency. Because diarrhea is still one of the most important causes of illness and death among children in developing countries, where the population turns to traditional medicine for its treatment, the present study determined the composition of fruit and leaf extracts of P. cauliflora, analyzed the activity against diarrhea by antimicrobial and gastrointestinal motility, and evaluated the cytotoxicity of the extracts. Chemical composition was determined by high-performance liquid chromatograpy-ultraviolet/photodiode array detection. Antimicrobial activity was analyzed by agar diffusion and the microdilution method against etiological agents of diarrhea. The effect on gastrointestinal motility was analyzed using an experimental model in mice. Cytotoxicity was evaluated in vitro with the fibroblast cell line SIRC CCL 60, and leaf extract showed a 50% inhibitory concentration of 0.48 μg/mL. Gallic acid, ellagic acid, and flavonoid derivatives were detected in the extracts. It was observed that fruit and leaf extracts showed some activity against Enterococcus faecalis, Escherichia coli, Salmonella sp., and Shigella sp. However, neither extract had any effect on gastrointestinal motility.  相似文献   
852.
A systematic review provides the best summary of evidence for clinical decision‐making in nephrology by summarizing all the primary studies that evaluate a specific clinical question. By using rigorous and pre‐specified methods, conclusions about the overall effect of an intervention can be more reliable, precise and comprehensive in a systematic review than those derived from individual studies. In this article, we describe the key components of a systematic review and meta‐analysis. We summarize the features of a systematic review that should be looked for when considering the accuracy and validity of its results – particularly when applying the outcomes of a systematic review to a clinical question.  相似文献   
853.
COPD is nowadays the main indication for lung transplantation. In appropriately selected patients with end stage COPD, lung transplantation may improve quality of life and prognosis of survival. However, patients with end stage COPD may die while waiting for lung transplantation. Palliative care is important to address the needs of patients with end stage COPD. This case report shows that in a patient with end stage COPD listed for lung transplantation offering palliative care and curative-restorative care concurrently may be problematic. If the requirements to remain a transplantation candidate need to be met, the possibilities for palliative care may be limited. Discussing the possibilities of palliative care and the patient's treatment preferences is necessary to prevent that end-of-life care needs of COPD patients dying while listed for lung transplantation are not optimally addressed. The patient's end-of-life care preferences may ask for a clear distinction between the period in which palliative and curative-restorative care are offered concurrently and the end-of-life care period. This may be necessary to allow a patient to spend the last stage of life according to his or her wishes, even when this implicates that lung transplantation is not possible anymore and the patient will die because of end stage COPD.  相似文献   
854.
855.

Aims

to investigate the association between admission hyperglycemia and myocardial damage in patients with ST-segment elevation myocardial infarction (STEMI) using Cardiac Magnetic Resonance (CMR).

Methods

We analyzed 113 patients with STEMI treated with successful primary percutaneous coronary intervention. Admission hyperglycemia was defined as a glucose level ≥ 7.8 mmol/l. Contrast-enhanced CMR was performed between 3 and 7 days after reperfusion to evaluate left ventricular function and perfusion data after injection of gadolinium-DTPA. First-pass images (FP), providing assessment of microvascular obstruction and Late Gadolinium Enhanced images (DE), reflecting the extent of infarction, were investigated and the extent of transmural tissue damage was determined by visual scores.

Results

Patients with a supramedian FP and DE scores more frequently had left anterior descending culprit artery (p = 0.02 and <0.001), multivessel disease (p = 0.02 for both) and hyperglycemia (p < 0.001). Moreover, they were characterized by higher levels of HbA1c (p = 0.01 and 0.04), peak plasma Creatine Kinase (p < 0.001), left ventricular end-systolic volume (p = 0.005 and <0.001), and lower left ventricular ejection fraction (p = 0.001 and <0.001). In a multivariate model, admission hyperglycemia remains independently associated with increased FP and DE scores.

Conclusion

Our results show the existence of a strong relationship between glucose metabolism impairment and myocardial damage in patients with STEMI. Further studies are needed to show if aggressive glucose control improves myocardial perfusion, which could be assessed using CMR.  相似文献   
856.
Although cardiac resynchronization therapy (CRT) is an effective treatment for chronic systolic heart failure with dyssynchrony, about one-third of patients do not respond favorably. The interaction between the pacing lead and the coronary sinus (CS) branches is of paramount importance for an effective resynchronization. Minor changes in lead position overtime could interfere with CRT mechanics, without affecting even biophysical parameters or ECG morphology. Although late post-implant CS lead dislodgement rate is consistent, lead movements have been little investigated and only with bi-dimensional methods. The aim of this study was (1) to develop a method for quantifying CS lead position in the 3D domain throughout the cardiac cycle and (2) to test it by comparing the CS lead position at implant and at follow-up, using chest fluoroscopy. Method performance, its accuracy and reproducibility were qualitatively and quantitatively assessed. Intra- and inter-observer percent discordance between trajectories were also computed. The accuracy of the procedure resulted in 0.3 ± 0.1 mm and its resolution was 0.5 mm. Intra- and inter-observer discordances were 2.2 ± 1.5 and 5.5 ± 3.6 mm, respectively. The proposed method for measuring the CS lead dynamic placement in 3D space seems accurate and reproducible. Investigating CS lead 3D dynamics could provide further insights into CRT mechanics.  相似文献   
857.
Magdalena Stepien  Talita Duarte‐Salles  Veronika Fedirko  Anne Floegel  Dinesh Kumar Barupal  Sabina Rinaldi  David Achaintre  Nada Assi  Anne Tj?nneland  Kim Overvad  Nadia Bastide  Marie‐Christine Boutron‐Ruault  Gianluca Severi  Tilman Kühn  Rudolf Kaaks  Krasimira Aleksandrova  Heiner Boeing  Antonia Trichopoulou  Christina Bamia  Pagona Lagiou  Calogero Saieva  Claudia Agnoli  Salvatore Panico  Rosario Tumino  Alessio Naccarati  H. B. Bueno‐de‐Mesquita  Petra H. Peeters  Elisabete Weiderpass  J. Ramón Quirós  Antonio Agudo  María‐José Sánchez  Miren Dorronsoro  Diana Gavrila  Aurelio Barricarte  Bodil Ohlsson  Klas Sj?berg  M?rten Werner  Malin Sund  Nick Wareham  Kay‐Tee Khaw  Ruth C. Travis  Julie A. Schmidt  Marc Gunter  Amanda Cross  Paolo Vineis  Isabelle Romieu  Augustin Scalbert  Mazda Jenab 《International journal of cancer. Journal international du cancer》2016,138(2):348-360
Perturbations in levels of amino acids (AA) and their derivatives are observed in hepatocellular carcinoma (HCC). Yet, it is unclear whether these alterations precede or are a consequence of the disease, nor whether they pertain to anatomically related cancers of the intrahepatic bile duct (IHBC), and gallbladder and extrahepatic biliary tract (GBTC). Circulating standard AA, biogenic amines and hexoses were measured (Biocrates AbsoluteIDQ‐p180Kit) in a case‐control study nested within a large prospective cohort (147 HCC, 43 IHBC and 134 GBTC cases). Liver function and hepatitis status biomarkers were determined separately. Multivariable conditional logistic regression was used to calculate odds ratios and 95% confidence intervals (OR; 95%CI) for log‐transformed standardised (mean = 0, SD = 1) serum metabolite levels and relevant ratios in relation to HCC, IHBC or GBTC risk. Fourteen metabolites were significantly associated with HCC risk, of which seven metabolites and four ratios were the strongest predictors in continuous models. Leucine, lysine, glutamine and the ratio of branched chain to aromatic AA (Fischer's ratio) were inversely, while phenylalanine, tyrosine and their ratio, glutamate, glutamate/glutamine ratio, kynurenine and its ratio to tryptophan were positively associated with HCC risk. Confounding by hepatitis status and liver enzyme levels was observed. For the other cancers no significant associations were observed. In conclusion, imbalances of specific AA and biogenic amines may be involved in HCC development.  相似文献   
858.
The modern approach to regenerative treatment of periodontal intraosseous defects should aim at maximizing the clinical outcomes while minimizing the invasiveness (pain, complications, aesthetic impairment, chair time, and costs) of the procedure. The present systematic review evaluated the effect of flap design, regenerative technology, and perioperative and postoperative adjunctive protocols on invasiveness. Overall, the results of the 13 included trials indicate that: (a) the elevation of a single (buccal or lingual) flap positively influences the intensity of postoperative pain and improves the quality of early wound healing compared with double flaps; (b) while the adjunctive use of a membrane is associated with significantly longer surgery-related chair time and higher postoperative pain, the adjunctive use of enamel matrix derivative at sites receiving a graft significantly reduces postoperative pain; also, graft materials showed no significant impact on invasiveness; (c) open flap debridement performed through the elevation of a single flap may lead to substantial clinical improvements of the lesion with reduced surgery-related chair time and costs, thus representing a promising alternative to regenerative treatment. However, for such an approach, a histological evaluation of the nature of the reconstructed tissues is still lacking, and the presurgery conditions (eg, probing depth, defect severity, and defect morphology), which may benefit in terms of invasiveness, have not yet been defined; and (d) intraoperative and postoperative low-level laser biostimulation of the defect site may favorably modulate the postoperative course.  相似文献   
859.
860.
The presence of a peri-implant bone dehiscence (BD) or fenestration (BF) is a common finding after implant placement in a crest with a reduced bucco-lingual bone dimension. The presence of a residual BD is associated with a relevant incidence of peri-implant biological complications over time. Guided bone regeneration (GBR), performed at implant placement, is the most validated treatment to correct a BD. In the present systematic review, the evidence evaluating factors which could reduce the invasiveness of a GBR procedure with respect to patient-reported outcomes, intra- and post- surgical complications, was summarized. Factors included were: technical aspects, regenerative materials for GBR, and peri- and post-operative pharmacological regimens. The available evidence seems to indicate that the use of membrane fixation and flap passivation by means of a double flap incision technique may reduce the incidence of post-surgical complications. When feasible, the coronal advancement of the lingual flap is suggested. The use of a non-cross linked resorbable membrane positively impacts on patient discomfort. The adjunctive use of autogenous bone to a xenograft seems not to improve BD correction, but could increase patient discomfort. Systemic antibiotic administration after a GBR procedure does not seem to be justified in systemically healthy 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