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   1902篇
  免费   111篇
  国内免费   11篇
耳鼻咽喉   18篇
儿科学   75篇
妇产科学   45篇
基础医学   246篇
口腔科学   47篇
临床医学   105篇
内科学   474篇
皮肤病学   56篇
神经病学   160篇
特种医学   42篇
外科学   212篇
综合类   11篇
预防医学   219篇
眼科学   26篇
药学   143篇
中国医学   16篇
肿瘤学   129篇
  2023年   9篇
  2022年   11篇
  2021年   53篇
  2020年   28篇
  2019年   58篇
  2018年   53篇
  2017年   53篇
  2016年   47篇
  2015年   40篇
  2014年   80篇
  2013年   116篇
  2012年   147篇
  2011年   156篇
  2010年   74篇
  2009年   64篇
  2008年   109篇
  2007年   106篇
  2006年   110篇
  2005年   111篇
  2004年   93篇
  2003年   90篇
  2002年   85篇
  2001年   38篇
  2000年   46篇
  1999年   43篇
  1998年   19篇
  1997年   6篇
  1996年   14篇
  1995年   6篇
  1994年   10篇
  1993年   6篇
  1992年   13篇
  1991年   25篇
  1990年   14篇
  1989年   15篇
  1988年   13篇
  1987年   13篇
  1986年   9篇
  1985年   10篇
  1982年   2篇
  1979年   4篇
  1977年   2篇
  1976年   3篇
  1972年   2篇
  1971年   3篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1956年   1篇
  1932年   1篇
排序方式: 共有2024条查询结果,搜索用时 31 毫秒
61.

Purpose

The aim of this study is to correlate the ultrasound (US) appearance of the persistent double or bifid distal tendon of the biceps brachii muscle with anatomical and histological data. This will provide a new model to study the pathological distal biceps brachii tendon (DBBT).

Methods

The DBBT of 20 cadaveric elbows were examined with linear array broadband US transducers (frequency band 14–6 MHz) using an anterior approach. Trypan blue dye was injected underneath the paratenon under US guidance in 16 specimens. After they were dissected, five of them were processed to obtain histological slices stained with hematoxylin–eosin and antiserum to protein S100.

Results

At US, the DBBT is a tendon in which the fascicles are organized in two different hyperechoic components separated by a hyperechoic septum related to the endotenon. The endotenon is lax, flexible, and makes folding and gliding of the two portions feasible. The DBBT is surrounded by a hyperechoic paratenon adjacent to the tendon surface, which is only differentiable by US when dye is interposed between such structures.

Conclusions

The connective septum of endotenon located between the two main components of the DBBT is responsible for the US image of two separate tendons and functionally enables it to work as two separate entities, thus allowing respective folding and gliding. The paratenon surrounding the lacertus fibrosus and the DBBT plays an important stabilization role, enabling them to change shape and arrangement during joint motion. It is also an important conduit for nerves and blood vessels.  相似文献   
62.
Species of the Metastrongylus genus, the lung nematodes of pigs that require an intermediate host (earthworm) to complete their cycle, pose a potential risk to both livestock and humans. This parasite which can result in lung pathology and mixed infections with other pathogens (e.g. viruses) can be fatal to pigs. Although this genus is distributed worldwide, there are no classification keys for identifying this common parasite species. In this work, we take advantage of parasitological surveys of wild boar (Sus scrofa) in northern and central Spain and southern Poland to develop a morphological identification key for the five most common Metastrongylus species (Metastrongylus apri, Metastrongylus pudendotectus, Metastrongylus salmi, Metastrongylus confusus and Metastrongylus asymetricus). In addition, we provide the first record of M. confusus in Spain, probably unidentified until now due to the lack of appropriate identification keys. We hope that this user-friendly identification key will enable parasitologists and veterinary practitioners to avoid further misclassifications of Metastrongylus species.  相似文献   
63.

Objective

Neuroticism and impulsivity are the personality variables most consistently associated with drug-dependent patients. To date, no data mining procedures have been applied to explore the differential role of personality variables in this population.

Methods

The personality profile of 336 drug-dependent patients was compared with that of a sample of community participants in the context of a decision tree learning approach using the Alternative Five Factor Model. The resulting discriminant model was cross-validated.

Results

Neuroticism and impulsivity were the most relevant variables in the resulting model, but their association appeared to be hierarchically organized. In the personality characterization of these patients, neuroticism became the main discriminant dimension, whereas impulsivity played a differential role, explained by means of an interaction effect. Decision tree learning models appear to be a heuristic theoretical and empirical approximation to the study of relevant variables, such as personality traits, in drug-dependency research.  相似文献   
64.
65.
66.
Transbronchial needle aspiration (TBNA) of pulmonary lesions without endobronchial affectation in combination with transbronchial biopsy (TBB) has been shown to increase diagnostic performance. The objective of this present study was to analyze whether the combination of TBNA with conventional TBB is a cost-effective approach.  相似文献   
67.
Magnetic porous silicon flakes (MPSF) were obtained from mesoporous silicon layers formed by multi-step anodization and subsequent composite formation with Fe oxide nanoparticles by thermal annealing. The magnetic nanoparticles adhered to the surface and penetrated inside the pores. Their structure evolved as a result of the annealing treatments derived from X-ray diffraction and X-ray absorption analyses. Moreover, by tailoring the magnetic load, the dynamic and hydrodynamic properties of the particles were controlled, as observed by the pressure displayed against a sensor probe. Preliminary functionality experiments were performed using an eye model, seeking potential use of MPSF as reinforcement for restored detached retina. It was observed that optimal flake immobilization is obtained when the MPSF reach values of magnetic saturation >10?4 A m2 g?1. Furthermore, the MPSF were demonstrated to be preliminarily biocompatible in vitro. Moreover, New Zealand rabbit in vivo models demonstrated their short-term histocompatibility and their magnetic functionality as retina pressure actuators.  相似文献   
68.
Background: Current scientific evidence addressing the relationship between periodontitis and hypertension is limited to studies producing inconsistent results. Methods: All participants of an ongoing representative cohort of Puerto Rican elderly who were ≥70 years old and residing in the San Juan metropolitan area were invited to this cross‐sectional study. Periodontal probing depth (PD) and attachment loss (AL) were summarized using the Centers for Disease Control and Prevention and the American Academy of Periodontology definition for severe periodontitis (≥2 teeth with AL ≥6 mm and ≥1 tooth with PD ≥5 mm). Three repeated blood pressure (BP) measurements taken were averaged using a standardized auscultatory method. Information on hypertension history, use of antihypertensive medications, and potential confounders (age, sex, smoking, heavy and binge drinking, diabetes, use of preventive dental services, flossing, body mass index, consumption of fruits, vegetables, whole wheat bread, and high‐fiber cereal) was collected during in‐person interviews. High BP was defined as average systolic BP ≥140 mm Hg or diastolic ≥90 mm Hg. Multivariate logistic regression models were used to study the relationship between severe periodontitis, hypertension history, and high BP. Results: The study population comprised 182 adults. In multivariate analysis, there was no association between severe periodontitis and hypertension history (odds ratio [OR] = 0.99; 95% confidence interval [CI]: 0.40 to 2.48). Severe periodontitis was associated with high BP, with OR of 2.93 (95% CI: 1.25 to 6.84), after adjusting for age, sex, smoking, and binge drinking. This association was stronger when restricted to those with hypertension or taking antihypertensive medications: OR = 4.20 (95% CI: 1.28 to 13.80). Conclusion: The results of this study suggest that periodontitis may contribute to poor BP control among older adults.  相似文献   
69.
BackgroundThe growth differentiation factor 15 (GDF-15) has been shown up-regulated in stress conditions and to have regulatory actions in myocyte hypertrophy. We hypothesized that GDF-15 could be related to disease severity and functional status in patients with hypertrophic cardiomyopathy (HCM).Methods and resultsWe performed a study which includes 102 consecutive outpatient HCM subjects, 73% males, aged 47.1 ± 14.6 years. A complete history and clinical examination was performed, including 12-lead electrocardiogram, echocardiography, symptom-limited treadmill exercise, 24-hour ECG-Holter monitoring, and magnetic resonance with Gadolinium. Several biomarkers, associated with myocardial remodeling and damage, were compared to GDF-15 levels. The assays were performed with commercial ELISAs or standardized methods when available. There was a significant association between GDF-15 levels and comorbidities, being higher in hypertension (p = 0.001), diabetes (p = 0.030), atrial fibrillation (p = 0.012), dyspnea (p = 0.020) and NYHA  II functional class (p = 0.037). GDF-15 levels were positively correlated with clinical variables (age, worse exercise capacity and mild renal dysfunction) and biomarkers of interstitial remodeling, such as metalloproteinase-2 (r: 0.40; p = 0.009), N-terminal pro-B-type natriuretic peptide (r: 0.28; p = 0.049), high-sensitivity troponin T (r: 0.30; p = 0.003) and von Willebrand factor (r: 0.33; p = 0.001). Multivariate analysis was assessed to estimate the involvement of these different factors in the GDF-15 levels, confirming the independent implication of severe dyspnea and functional status.ConclusionsThe present results show that higher levels of GDF-15 are associated to conditions of severe disease in HCM. Hence, GDF-15 is suggested as a novel marker related to the severity and could represent a further useful tool in monitoring functional capacity of HCM patients.  相似文献   
70.
Objective: To evaluate long-term outcomes in patients maintaining a nevirapine (NVP)-based regimen. Methods: Retrospective, multicenter, cohort study including patients currently receiving an NVP regimen that had been started at least 5 years previously. Demographic, clinical, and analytical variables were recorded. Results: Median follow-up was 8.9 (5.7-11.3) years. Baseline characteristics: 74% men, 47 years old, 36% drug users, 40% AIDS, 40% HCV+, 51.4% detectable HIV-1 viral load, CD4 count 395 (4-1,421)/μL, 19% CD4 < 200/μL, 27% ALT grade 1-2, 36% AST grade 1-2. Thirty percent ART-naive, 83%received NVP associated with 2 nucleoside analogues during the study period, and 17% a protease inhibitor. A significant improvement was observed in general health status markers, including hemoglobin, platelets, and albumin, regardless of HCV coinfection. CD4 cell gain was +218 and +322/μL after 6 and 9 years, respectively (+321 and +391 in naive patients). Triglycerides significantly decreased in pretreated patients, whereas the percentage of patients with HDLc < 1.03 mmol/L and LDL-c > 3.37 mmol/L significantly decreased in a subsample with available values. A significant decrease in transaminases, alkaline phosphatase, and Fib4 score was observed, mainly in HCV+ and ARV-naive patients. Conclusions: In patients who tolerate NVP therapy, (even those with HCV coinfection), long term benefits may be significant in terms of a progressive improvement in general health status markers and CD4 response, a favorable lipid profile, and good liver tolerability.  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