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   3245篇
  免费   223篇
  国内免费   15篇
耳鼻咽喉   20篇
儿科学   126篇
妇产科学   95篇
基础医学   520篇
口腔科学   36篇
临床医学   275篇
内科学   772篇
皮肤病学   80篇
神经病学   393篇
特种医学   86篇
外科学   314篇
综合类   13篇
一般理论   1篇
预防医学   206篇
眼科学   24篇
药学   226篇
中国医学   5篇
肿瘤学   291篇
  2024年   5篇
  2023年   44篇
  2022年   110篇
  2021年   146篇
  2020年   100篇
  2019年   124篇
  2018年   114篇
  2017年   98篇
  2016年   107篇
  2015年   124篇
  2014年   167篇
  2013年   188篇
  2012年   301篇
  2011年   294篇
  2010年   150篇
  2009年   136篇
  2008年   251篇
  2007年   202篇
  2006年   167篇
  2005年   180篇
  2004年   133篇
  2003年   114篇
  2002年   80篇
  2001年   13篇
  2000年   10篇
  1999年   12篇
  1998年   14篇
  1997年   13篇
  1996年   16篇
  1995年   4篇
  1994年   4篇
  1993年   9篇
  1992年   6篇
  1991年   6篇
  1990年   3篇
  1988年   5篇
  1987年   1篇
  1986年   7篇
  1985年   4篇
  1984年   6篇
  1983年   1篇
  1980年   3篇
  1979年   1篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1971年   2篇
  1970年   2篇
  1967年   1篇
  1966年   1篇
排序方式: 共有3483条查询结果,搜索用时 15 毫秒
11.
Anastomosis   总被引:6,自引:1,他引:5  
Esophageal anastomosis is still associated with a high rate of complications even though they have decreased considerably in recent years. Anastomotic leaks are more frequent in the neck than in the chest, and related mortality rate is not different. The leakage incidence does not depend on suture materials or on technical modalities used to perform the anastomosis. In fact, there is no difference between the leakage rate when comparing manual and mechanical anastomoses. The leak incidence after both mechanical and manual anastomoses is much higher in collective reviews than in reports coming from leading centers. Frequent esophageal surgeons can learn from their previous experience and therefore avoid technical errors, whereas casual esophageal surgeons do not have this opportunity. Performing an esophageal anastomosis is a technical matter, and suture healing is independent of the patient's biologic situation. Anastomotic fibrotic stricutures are frequent after both manual and mechanical anastomoses, and most can be avoided by meticulous suturing technique.
Resumen La anastomosis esofágica todavía se asocia con una elevada incidencia de complicaciones, a pesar de que éstas han descendido en forma considerable en los últimos años. Las fugas anastomóticas son más frecuentes en el cuello que en el tórax y las tasas de mortalidad no son diferentes. La rata de fuga anastomótica no depende de los materiales de sutura o de las modalidades técnicas que se utilicen para realizar la anastomosis. De hecho no hay diferencia en cuanto a la rata de fugas entre las anastomosis manuales y las mecánicas. La incidencia de fuga, tanto en las manuales como en las mecánicas, es bastante más alta en las revisiones colectivas que en los reportes emanados de los centros médicos de mayor importancia. Los cirujanos especialistas en esófago tienen la posibilidad de aprender de sus experiencias previas y con ello evitar los errores técnicos, en tanto que aquellos cirujanos ocasionales no la poseen. La realización de una anastomosis esofágica es un asunto técnico y la cicatrización de la sutura es independiente de la condición biológica del paciente. Las estrecheces fibróticas de las anastomosis son frecuentes luego de las anastomosis manuales, al igual que luego de las anastomosis mecánicas y la mayoría puede ser evitada mediante una técnica meticulosa.

Résumé Le taux de complications des anastomoses oesophagiennes, même s'il y en a moins ces dernières années, reste toujours élevé. La fréquence de fistules est plus grande quand l'anastomose est faite au cou par rapport au thorax, mais la mortalité n'en est pas très différente. L'incidence de fistules ne dépend ni du matériau de suture ni des modalités d'anastomoses utilisées. Il n'y a aucune différence lorsque les anastomoses manuelles sont comparées aux anastomoses méchaniques: L'incidence des fistules, que ce soit à la main ou à la machine est plus élevée dans les séries collectives par rapport à celle des centres spécialisés. Les chirurgiens qui font des anastomoses de façon régulière ont la possibilité de profiter de leur expérience et ainsi d'éviter les erreurs techniques, alors que le chirurgien occasionnel de l'oesophage n'a pas cette possibilité. L'anastomose oesophagienne est techniquement difficile et la cicatrisation est indépendante de l'état clinique et biologique du patient. Les sténoses fibreuses sont aussi fréquentes après les anastomoses manuelles qu'après les anastomoses méchaniques, mais la plupart peuvent être évitées par une technique méticuleuse.
  相似文献   
12.
MR imaging of the neonatal brain at 3 Tesla   总被引:1,自引:0,他引:1  
3 Telsa MR scanners are now becoming more widely available and 3 Telsa is likely to become the filed strength of choice for clinical imaging of the brain. The neonatal brain can be safely and successfully imaged at 3 Telsa. The improved signal to noise afforded by a higher field strength may be used to improve image quality or shorten acquisition times. This may be exploited for conventional T1 and T2 weighted imaging and also for advanced techniques such as diffusion tensor imaging, angiography and functional magnetic resonance studies.  相似文献   
13.
Mental imagery is part of people''s own internal processing and plays an important role in everyday life, cognition and pathology. The neural network supporting mental imagery is bottom‐up modulated by the imagery content. Here, we examined the complex associations of gender and age with the neural mechanisms underlying emotion imagery. We assessed the brain circuits involved in emotion mental imagery (vs. action imagery), controlled by a letter detection task on the same stimuli, chosen to ensure attention to the stimuli and to discourage imagery, in 91 men and women aged 14–65 years using fMRI. In women, compared with men, emotion imagery significantly increased activation within the right putamen, which is involved in emotional processing. Increasing age, significantly decreased mental imagery‐related activation in the left insula and cingulate cortex, areas involved in awareness of ones'' internal states, and it significantly decreased emotion verbs‐related activation in the left putamen, which is part of the limbic system. This finding suggests a top‐down mechanism by which gender and age, in interaction with bottom‐up effect of type of stimulus, or directly, can modulate the brain mechanisms underlying mental imagery.  相似文献   
14.
15.
16.
The problem of residues of toxic contaminants in food products has assumed considerable importance in terms of food safety. Naturally occurring contaminants, such as mycotoxins, are monitored routinely in the agricultural and food industries. Unfortunately, the consequences of the presence of mycotoxins in foodstuffs are evident in livestock farms, where both subacute and chronic effects on animal health are observed and could have non-negligible effects on human health. Ochratoxin A (OTA) is a common mycotoxin that contaminates food and feeds. Due to its thermal stability, the eradication of OTA from the food chain is very difficult. Consequently, humans and animals are frequently exposed to OTA in daily life. In this review article, we will devote time to highlighting the redox-based nephrotoxicity that occurs during OTA intoxication. In the past few decades, the literature has improved on the main molecules and enzymes involved in the redox signaling pathway as well as on some new antioxidant compounds as therapeutic strategies to counteract oxidative stress. The knowledge shown in this work will address the use of nutraceutical substances as dietary supplements, which would in turn improve the prophylactic and pharmacological treatment of redox-associated kidney diseases during OTA exposure, and will attempt to promote animal feed supplementation.  相似文献   
17.
Endorectal coil MRI in local staging of rectal cancer   总被引:5,自引:0,他引:5  
PURPOSE: The choice of the therapeutic strategies in patients affected with rectal cancer is strictly dependent by the tumor stage. So, in order to obtain an improvement in preoperative staging accuracy, new imaging modalities are now under investigation. The aim of this work is the evaluation of endorectal-coil MRI in the local staging of rectal cancer. MATERIAL AND METHODS: Fourty-three patients affected with histologically proven rectal cancer, have been evaluated by an high-field strength magnet (1.5 T). In 14/43 patients neoadjuvant pre-operative chemotherapy had been previously performed. In all cases axial SE T1w and FSE T2w sequences and coronal or sagittal FSE T2w sequences, with and without fat suppression, were performed. Basing upon the TNM staging system and the previously reported MRI signs the local extent of the tumor was evaluated, focusing about the rectal wall infiltration and the perirectal lymph nodes involvement. All the patients underwent surgery and a comparative evaluation of MRI and pathological staging was done. RESULTS: At MRI the tumor was detected in 38/43 patients. In evaluating wall infiltration the MRI results agreed with pathological results in 89% of patients and showed 92% accuracy in T1-T2 stage and 94% in T3. In evaluating perirectal lymph nodes metastases MRI showed 69% accuracy, 82% sensitivity and 55%specificity. DISCUSSION AND CONCLUSIONS: The poor accuracy of CT and body-coil MRI in evaluating wall involvement in patients with rectal cancer is mainly related to their inability to demonstrate the single layers of the rectal wall. So transrectal ultrasound is now the first choice modalitiy in local staging of rectal cancer. However transrectal ultrasound showed low sensitivity in detecting perirectal lymph nodes metastases and low accuracy in evaluating the patients previously undergone to neoadjuvant chemotherapy or radiotherapy. On the other hand the improvement of MRI sequences and the availability of the endorectal coils allowed to visualize the single layers of the rectal wall so making the endorectal-coil MRI a reliable imaging technique to stage rectal cancer. The results of our work demonstrate a good diagnostic accuracy of endorectal-coil MRI in local staging of rectal cancer, in particular the degree of rectal wall infiltration was well demonstrated, while the perirectal lymph nodes metastases were demonstrated with less accuracy. The long examination time, the costs and the movement-related artefacts are the main limits of MRI. In particular the movement-related artifacts sometime do not allow the visualization of the wall layers so lowering the diagnostic accuracy in demonstrating the tumor wall infiltration. In conclusion, even though endorectal coil MRI proved to be a reliable imaging technique in local staging of rectal cancer, at present we are not able to state what may be its real role in diagnostic evaluation of the patients with rectal cancer, in particular if compared to endorectal ultrasound. Further, comparative studies, based upon larger patients series are probably needed to draw a definitive conclusion.  相似文献   
18.
BackgroundWe aimed to study the implications of breast cancer (BC) subtypes for the development and prognosis of leptomeningeal carcinomatosis (LC).Patients and methodsData from the breast cancer patients diagnosed with LC between 2005 and 2010 were retrieved. Patients were classified in luminal A, B, HER2 positive and triple negative (TN) and their BC diagnosis, treatment, and outcome were analyzed according to each subtype. Pearson's chi-square and Fisher's exact test were used for categorical variables. Survival analyses were performed by Kaplan–Meier method and compared with the log-rank test.ResultsA total of 38 BC patients were identified, with a median age of 54.8 years (range 36–79). The proportion of luminal A, B, HER2 positive and TN was 18.4%, 31.6%, 26.3% and 23.7%, respectively. LC was the first evidence of metastatic disease in 5 BC patients. Twenty patients received the systemic chemotherapy, with 16 (80%) whole brain radiotherapy (WBRT). Nine patients received only WBRT. TN patients had the shorter interval between metastatic breast cancer diagnosis and the development of LC. Median survival after the diagnosis of LC (OSLC) was 2.6 months (range 1.2–6.4), and did not differ across breast cancer subtypes. In univariate analysis, performance status (ECOG = 0–2) and chemotherapy were prognostic for OSLC, but only the treatment stood as an independent prognostic factor in multivariate analysis.ConclusionsBreast cancer subtype influences the timing of LC appearance, but not OSLC. Patients with LC from breast cancer should be offered systemic treatment, as it appears to associate with the improved outcome. New therapeutic strategy, including, targeted and intrathecal therapy are deserved for BC patients with LC.  相似文献   
19.
Patients with adrenal incidentalomas (AIs) and subclinical hypercortisolism (SH) have increased risk of fracture independent of bone mineral density (BMD) and possibly due to reduced bone quality. The trabecular bone score (TBS) has been proposed as a index of bone microarchitecture. The aim of the study was to investigate TBS in AI. In 102 AI patients, SH was diagnosed in the presence of at least two of the following: (1) urinary free cortisol >70 µg/24 h (193.1 nmol/L); (2) cortisol after 1‐mg dexamethasone suppression test (1‐mg DST) >3.0 µg/dL (82.8 nmol/L); or (3) adrenocorticotropic hormone (ACTH) <10 pg/mL (<2.2 pmol/L). In patients and in 70 matched controls, BMD was measured at lumbar spine (LS) and femur (neck [FN] and total [FT]) by dual X‐ray absorptiometry and TBS was assessed in the region of LS‐BMD; BMD and TBS data were reported as Z‐scores. In patients, vertebral deformities were assessed by radiograph. Patients with SH (n = 34) had lower LS‐BMD (?0.31 ± 1.17), FT‐BMD (?0.29 ± 0.91), and TBS (?3.18 ± 1.21) than patients without SH (n = 68, 0.31 ± 1.42, p = 0.03; 0.19 ± 0.97, p = 0.01; ?1.70 ± 1.54, p < 0.0001, respectively) and controls (0.42 ± 1.52, p = 0.02; 0.14 ± 0.76, p = 0.02; ?1.19 ± 0.99, p < 0.0001, respectively). TBS was inversely correlated with 1‐mg DST (β = ?0.26, t = ?2.79, p = 0.006) regardless of age, LS‐BMD, body mass index (BMI), and gender. The presence of fracture was associated with low TBS alone (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.85–12.42, p = 0.001) and with the cluster low TBS plus low LS‐BMD (OR, 4.37; 95% CI, 1.71–11.4, p = 0.002), after adjustment for age, BMI, and gender. Low TBS plus low LS‐BMD showed a good specificity (79%) for predicting fractures, whereas normal TBS (ie, > ?1.5) plus normal LS‐BMD high specificity (88.1%) for excluding fractures. Finally, TBS predicted the occurrence of a new fracture in 40 patients followed for 24 months (OR, 11.2; 95%CI, 1.71–71.41, p = 0.012) regardless of LS‐BMD, BMI, and age. In SH, bone quality, as measured by TBS, is altered. TBS is useful in detecting AI patients at risk of fractures. © 2012 American Society for Bone and Mineral Research.  相似文献   
20.
It is widely accepted that elevated protease activity (EPA) in chronic wounds impedes healing. However, little progress has occurred in quantifying the level of protease activity that is detrimental for healing. The aim of this study was to determine the relationship between inflammatory protease activity and wound healing status, and to establish the level of EPA above which human neutrophil‐derived elastase (HNE) and matrix metalloproteases (MMP) activities correlate with nonhealing wounds. Chronic wound swab samples (n = 290) were collected from four wound centers across the USA to measure HNE and MMP activity. Healing status was determined according to percentage reduction in wound area over the previous 2–4 weeks; this was available for 211 wounds. Association between protease activity and nonhealing wounds was determined by receiver operating characteristic analysis (ROC), a statistical technique used for visualizing and analyzing the performance of diagnostic tests. ROC analysis showed that area under the curve (AUC) for HNE were 0.69 for all wounds and 0.78 for wounds with the most reliable wound trajectory information, respectively. For MMP, the corresponding AUC values were 0.70 and 0.82. Analysis suggested that chronic wounds having values of HNE >5 and/or MMP ≥13, should be considered wound healing impaired. EPA is indicative of nonhealing wounds. Use of a diagnostic test to detect EPA in clinical practice could enable clinicians to identify wounds that are nonhealing, thus enabling targeted treatment with protease modulating therapies.  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