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   18328篇
  免费   853篇
  国内免费   125篇
耳鼻咽喉   105篇
儿科学   637篇
妇产科学   505篇
基础医学   2063篇
口腔科学   495篇
临床医学   1357篇
内科学   4854篇
皮肤病学   311篇
神经病学   1907篇
特种医学   797篇
外国民族医学   2篇
外科学   2420篇
综合类   51篇
一般理论   2篇
预防医学   831篇
眼科学   228篇
药学   1017篇
中国医学   12篇
肿瘤学   1712篇
  2024年   32篇
  2023年   133篇
  2022年   276篇
  2021年   462篇
  2020年   272篇
  2019年   382篇
  2018年   477篇
  2017年   349篇
  2016年   481篇
  2015年   479篇
  2014年   680篇
  2013年   867篇
  2012年   1318篇
  2011年   1310篇
  2010年   760篇
  2009年   689篇
  2008年   1259篇
  2007年   1130篇
  2006年   1206篇
  2005年   1114篇
  2004年   1102篇
  2003年   987篇
  2002年   904篇
  2001年   193篇
  2000年   141篇
  1999年   208篇
  1998年   190篇
  1997年   162篇
  1996年   132篇
  1995年   132篇
  1994年   116篇
  1993年   120篇
  1992年   119篇
  1991年   101篇
  1990年   96篇
  1989年   80篇
  1988年   72篇
  1987年   72篇
  1986年   74篇
  1985年   52篇
  1984年   82篇
  1983年   47篇
  1982年   59篇
  1981年   42篇
  1980年   45篇
  1979年   31篇
  1978年   36篇
  1977年   25篇
  1976年   20篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
21.
Calcifications can develop within the crypts of the palatine tonsil. During routine dental panoramic radiography, these tonsillar calcifications, or tonsilloliths, may be visualized superimposed upon the mandibular ramus. Their anatomic location and radiographic appearance are such that confusion with parotid sialolithiasis may occur. This report defines the symptomatology and differential diagnosis of these tonsilloliths.  相似文献   
22.
Objective: The aims of this work were to histologically examine the healing of mineralized human bone allograft (MHBA) in sinus augmentation for elevating a severe maxillary atrophy ridge (≤2 mm residual ridge height) and to correlate the results to the sinus cavity size. Material and methods: A two‐stage protocol was conducted in 23 patients, all having crestal bone ≤2 mm. A mixture of 80/20 cortical/cancellous of MHBA particles was used to augment sinus using the lateral window approach in narrow (NS; <15 mm bucco‐palatal distance) and wide (WS; ≥15 mm bucco‐palatal distance) sinuses, based upon computerized tomography (CT) assessment. A bone core biopsy was taken at implant placement, 6 and 9 months after surgery. Microradiography, histology and histochemistry of methacrylate‐embedded sections were performed to analyze and to evaluate the bone and graft amount. Results: Newly formed bone around MBHA particles was found in all 28 biopsies. Bone showed a woven structure at 6 months after surgery and a lamellar structure 9 months after surgery. At 6 months after surgery, the 13 NS and 15 WS had 30.5±8.8% and 20.7±4.9% mean±SD bone formation, respectively. At 9 months after surgery, it was 38.8±7% (NS) and 30.7±3% (WS). Residual graft was about 16% (6 months) and 6% (9 months), in both NS and WS. The Mann–Whitney test showed a greater bone formation in NS than in WS (P<0.005). Conclusions: The used 80/20 MHBA mixture appears to promote, in the severe atrophic maxilla, a satisfactory bone formation. Our results prove that the larger the sinus, the longer the maturation time needed to achieve a suitable amount of new bone formation. To cite this article:
Maria Soardi C, Spinato S, Zaffe D, Wang H‐L. Atrophic maxillary floor augmentation by mineralized human bone allograft in sinuses of different size: an histologic and histomorphometric analysis.
Clin. Oral Impl. Res. 22 , 2011; 560–566
doi: 10.1111/j.1600‐0501.2010.02034.x  相似文献   
23.
Objective. Impulsivity represents a key dimension in obsessive–compulsive disorder (OCD), in relation to outcome and course. It can be assessed through the Barratt Impulsiveness Scale (BIS), which explores three main areas: attentional, motor, and nonplanning. Present study was aimed to assess level of impulsivity in a sample of OCD patients, in comparison with healthy controls, using the BIS. Methods. Seventy-five OCD outpatients, 48 of them having psychiatric comorbidities and 70 healthy controls, were assessed through the BIS, and their scores were analyzed using Student's t-test for independent samples, on the basis of demographic and clinical characteristics. Results. BIS total scores were significantly higher (P: 0.01) in patients compared to controls, with no difference between pure and comorbid patients. Attentional impulsivity scores were significantly higher than controls in patients with pure (P < 0.001) and comorbid OCD (P < 0.001), without differences among them. Patients with multiple OC phenotypes showed higher, though statistically non significant, total and attentional scores, compared to single phenotype patients. In addition, patients with comorbid major depressive disorder had higher, though statistically non significant, total and attentional scores, compared to patients with comorbid bipolar disorder, generalized anxiety disorder, and other disorders. Conclusions. Present findings showed higher impulsivity levels in OCD patients versus controls, particularly in the attentional area, and ultimately suggest a potential cognitive implication.  相似文献   
24.
Patent foramen ovale (PFO) is a common congenital anatomical defect in the general population with a mean prevalence of 20 %. Transcranial Doppler sonography and echocardiography, both with infusion of agitated saline as an echo contrast, have been introduced for the diagnosis of PFO. Transesophageal echocardiography is considered the gold standard. Several studies have suggested an association between cryptogenetic stroke and PFO, but the role of this condition as a risk factor for stroke is still debated. The aims of this prospective multicentre study are the evaluation of PFO prevalence in the whole ischemic stroke population and the identification of a stroke recurrence profile risk in patients with PFO. All consecutive patients admitted for acute ischemic stroke and with a confirmed diagnosis at discharge are eligible cases for the study. Demographic and vascular risk factors are registered. Clinical severity is summarized by the National Institute of Health stroke scale. Echocardiographic and transcranial studies are performed in each patient to detect the presence of PFO. Prevalence of PFO will be calculated with 95 % CIs. Univariate analysis will be performed to detect the correlation of PFO with different registered factors and multivariable analysis with PFO as independent variable. The present study should contribute to better identify the role of PFO in ischemic stroke risk and recurrence-related events. Qualifying findings of the study are represented by the high number of enrolled patients, the prospective methodology of the study and the presence of secondary instrumental endpoints.  相似文献   
25.
Notwithstanding fundamental methodological advancements, scientific information about disorders of consciousness (DOCs)—e.g. Vegetative State/Unresponsive Wakefulness Syndrome (VS/UWS) and Minimally Conscious State (MCS)—is incomplete. The possibility to discriminate between different levels of consciousness in DOC states entails treatment strategies and ethical concerns. Here we attempted to investigate Italian clinicians’ and basic scientists’ opinions regarding some issues emerging from the care and the research on patients with DOCs. From our survey emerged that Italian physicians working with patients with DOCs give a central role to ethics. Current Italian regulation regarding basic research conducted in patients with DOCs apparently risks to be inadequate to support scientific advancement, and would deserve a different assessment compared to ordinary treatments. We think the results of our survey deserve attention from an international audience because they exemplify the difficulty to define a shared approach to the issues related to patients with DOCs and the necessity to better assess both the ordinary and experimental treatment of patients with DOCs at the ethical and legal level.  相似文献   
26.
After three proceedings in which neuroscience was a relevant factor for the final verdict in Italian courts, for the first time a recent case puts in question the legal relevance of neuroscientific evidence. This decision deserves international attention in its underlining that the uncertainty still affecting neuroscientific knowledge can have a significant impact on the law. It urges the consideration of such uncertainty and the development of a shared management of it.  相似文献   
27.
Coronary spasm during coronary angiography for vasculopathy in children can be prevented by the intracoronary administration of nitroglycerin. We reviewed the anesthesia and catheterization reports and charts for pediatric transplant recipients who underwent angiography from 2005 through 2010. Correlation analysis was used to study the relation of post-injection systolic blood pressure (SBP) to nitroglycerin dose. Forty-one angiographic evaluations were performed on 25 patients (13 male and 12 female). Mean age was 9.9 ± 3.2 years (range, 3.3–16.1 yr). The mean total dose of nitroglycerin was 2.93 ± 1.60 µg/kg (range, 1–8 µg/kg).There was a significant drop between the baseline SBP (mean, 106 ± 21.6 mmHg) and the lowest mean SBP before nitroglycerin administration (78 ± 13.2, P <0.0001, paired t test). There was no significant additional change in SBP (mean after nitroglycerin administration, 80.7 ± 13.1 mmHg; P = 0.2). There was a significant drop in lowest heart rate between baseline (109 ± 16.5 beats/min) and before nitroglycerin administration (89 ± 14.3 beats/min; P <0.0001, paired t test). There was no significant additional change in heart rate (mean heart rate after nitroglycerin, 84 ± 17.7 beats/min; P = 0.09). There were 2 interventions for SBP before nitroglycerin and 2 after nitroglycerin. One child experienced a transient ST-T–segment change during angiography after nitroglycerin. In the highest dose range, the additional decrease in SBP was 7.2 mmHg (P=0.03). Routine intracoronary nitroglycerin administration in this dose range produced no significant changes in SBP or heart rate in children.Key words: Child, coronary angiography, coronary vasospasm/etiology, dose-response relationship, drug, heart transplantation/adverse effects, hemodynamics/drug effects, nitroglycerin/administration & dosage/therapeutic use, postoperative complications/therapy, retrospective studies, vasodilation/drug effectsAllograft coronary disease in children occurs with increasing frequency after transplantation, as a function of time. In a multicenter study,1 the incidence of coronary artery disease in children 5 years post-transplant was 17% of all recipients. Coronary angiography remains the gold standard in the detection of vasculopathy in heart-transplant recipients.2 Coronary artery spasm can complicate selective coronary angiography and result in myocardial ischemia. Coronary spasm can simulate the angiographic appearance of graft vasculopathy and cause diagnostic confusion.3 The spasm can arise from manipulation of the arterial wall by the catheter or from intraluminal injection of contrast material. In cardiac transplant recipients, coronary artery spasm has been reported in as many as 4.9% of coronary angiograms.3In adults, intracoronary nitroglycerin is routinely administered during coronary angiography to prevent coronary artery spasm.4 In children, however, safety and dosage guidelines for intracoronary nitroglycerin have not yet been firmly established. A dose of 3 µg/kg can be extrapolated by weight from the established adult dose of 200 µg; this dose was used in a study of children after the arterial switch operation and was shown to produce coronary vasodilation—with a small reduction in systolic blood pressure (SBP) and no noteworthy change in heart rate—in a control group of patients.5,6We previously reported a case of coronary artery spasm during routine coronary angiographic monitoring in a 9-year-old boy who had undergone heart transplantation as an infant.7 After left main coronary artery injection of contrast material, the patient''s left anterior descending and left circumflex coronary arteries appeared to be diffusely narrow, and he developed marked ST-segment elevation, hypotension, and ventricular tachycardia. After cardiopulmonary resuscitation, he recovered uneventfully and displayed normal systolic function. Coronary angiography one month later, with the administration of intracoronary nitroglycerin before the injection of contrast material, revealed normal coronary artery diameter and was accomplished without complication.Since 2005, intracoronary nitroglycerin has routinely been used in pediatric transplant patients during biennial selective coronary angiographic monitoring at our institution. The purpose of the study is to report our experience with the routine use of intracoronary nitroglycerin for coronary angiography in children: its effects on blood pressure, on heart rate, and on the occurrence of arrhythmia and ST-segment elevation.  相似文献   
28.
Since the mechanisms by which specific immunity destroys Her-2/neu carcinoma cells are highly undetermined, these were assessed in BALB/c mice vaccinated with plasmids encoding extracellular and transmembrane domains of the protein product (p185(neu)) of the rat Her-2/neu oncogene shot into the skin by gene gun. Vaccinated mice rejected a lethal challenge of TUBO carcinoma cells expressing p185(neu). Depletion of CD4 T cells during immunization abolished the protection, while depletion of CD8 cells during the effector phase halved it, and depletion of polymorphonuclear granulocytes abolished all protection. By contrast, Ig mu-chain gene KO mice, as well as Fcgamma receptor I/III, beta-2 microglobulin, CD1, monocyte chemoattractant protein 1 (MCP1), IFN-gamma, and perforin gene KO mice were protected. Only mice with both IFN-gamma and perforin gene KOs were not protected. Although immunization also cured all BALB/c mice bearing established TUBO carcinomas, it did not cure any of the perforin KO or perforin and IFN-gamma KO mice. Few mice were cured that had knockouts of the gene for Ig mu-chain, Fcgamma receptor I/III, IFN-gamma, or beta-2 microglobulin. Moreover, vaccination cured half of the CD1 and the majority of the MCP1 KO mice. The eradication of established p185(neu) carcinomas involves distinct mechanisms, each endowed with a different curative potential.  相似文献   
29.
Changes in gastrointestinal peptide release may play an important role in improving glucose control and reducing body weight following Roux-en-Y gastric bypass (RYGB), but the impact of low caloric intake on gut peptide release post-surgery has not been well characterized. The purpose of this study was to assess the relationships between low caloric intake and gut peptide release and how they were altered by RYGB. Obese females including ten normoglycemic (ON) and ten with type 2 diabetes mellitus (T2DM) (OD) were studied before, 1 week, and 3 months after RYGB. Nine lean, normoglycemic women were studied for comparison. Subjects were given three separate mixed meal challenges (MMCs; 75, 150, and 300 kcal). Plasma glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) were analyzed. Prior to surgery, only minimal increases in GLP-1 and PYY were observed in response to the MMCs. After surgery, the peak GLP-1 concentration was progressively elevated in response to increasing meal sizes. The meal sizes had a statistically significant impact on elevation of GLP-1 incremental areas under the curve (ΔAUC) in both ON and OD at 1 week and 3 months post-surgery visits (p?<?0.05 for all comparisons). The PYY ?AUC was also significantly increased in a meal size-dependent manner in both ON and OD at both post-surgery visits (p?<?0.05 for all comparisons). Meal sizes as small as 75–300 kcal, which cause minimal stimulation in GLP-1 or PYY release in the subjects before RYGB, are sufficient to provide statistically significant, meal size-dependent increases in the peptides post-RYGB both acutely and after meaningful weight loss occurred.  相似文献   
30.
Surgery had been the traditional treatment for native coarctation of the aorta, one of the most common cardiovascular congenital malformations. As a less invasive mode of treatment, balloon angioplasty has emerged as an alternative to surgery but has not gained universal acceptance due to its rates of restenosis secondary to vessel recoil and concerns over aortic wall injury resulting in aneurysm formation. To overcome these problems, endovascular stents were introduced in the management of this condition. The early- and intermediate-term results are encouraging, with low rates of restenosis and complications. In this article, the authors review the current evidence on coarctation stenting and discuss future trends in this area.  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