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   5100篇
  免费   359篇
  国内免费   25篇
耳鼻咽喉   61篇
儿科学   108篇
妇产科学   81篇
基础医学   733篇
口腔科学   721篇
临床医学   411篇
内科学   933篇
皮肤病学   232篇
神经病学   362篇
特种医学   122篇
外科学   623篇
综合类   14篇
一般理论   2篇
预防医学   475篇
眼科学   96篇
药学   285篇
中国医学   25篇
肿瘤学   200篇
  2024年   5篇
  2023年   62篇
  2022年   111篇
  2021年   247篇
  2020年   193篇
  2019年   244篇
  2018年   261篇
  2017年   179篇
  2016年   188篇
  2015年   215篇
  2014年   269篇
  2013年   335篇
  2012年   504篇
  2011年   486篇
  2010年   267篇
  2009年   210篇
  2008年   282篇
  2007年   286篇
  2006年   224篇
  2005年   182篇
  2004年   135篇
  2003年   104篇
  2002年   90篇
  2001年   54篇
  2000年   45篇
  1999年   45篇
  1998年   19篇
  1997年   7篇
  1996年   12篇
  1995年   11篇
  1994年   8篇
  1993年   10篇
  1992年   26篇
  1991年   20篇
  1990年   16篇
  1989年   10篇
  1988年   14篇
  1987年   7篇
  1986年   13篇
  1985年   10篇
  1984年   11篇
  1983年   7篇
  1979年   6篇
  1977年   6篇
  1976年   5篇
  1971年   5篇
  1969年   9篇
  1968年   4篇
  1966年   3篇
  1965年   3篇
排序方式: 共有5484条查询结果,搜索用时 15 毫秒
91.
Metabolic Brain Disease - Leptin is an adipose tissue-derived hormone that acts on the hypothalamus in order to maintain energy homeostasis. However, leptin can also induce an inflammatory...  相似文献   
92.
93.
Dengue is currently a major public-health problem. Dengue virus (DENV) is classified into four distinct serotypes, DENV 1-4. After 28 years of absence, DENV-4 was again detected in Brazil in 2010 in Roraima State, and one year later, the virus was identified in the northern Brazilian states of Amazonas and Pará, followed by Rio de Janeiro and São Paulo. In Minas Gerais, the first confirmed case of DENV-4 occurred in the municipality of Frutal in 2011 and has now been isolated from a growing number of patients. Although DENV-2 is associated with the highest risk of severe forms of the disease and death due to the infection, DENV-4 has also been associated with severe forms of the disease and an increasing risk of hemorrhagic manifestations. Herein, the first fatal case of confirmed DENV-4 in Brazil is reported. The patient was an 11-year-old girl from the municipality of Montes Claros in northern Minas Gerais State, Brazil. She had idiopathic thrombocytopenic purpura as a comorbid condition and presented with a fulminant course of infection, leading to death due to hemorrhagic complications. Diagnosis was confirmed by detection of Dengue-specific antibodies using IgM capture enzyme-linked immunosorbent assay and semi-nested RT-PCR. Primary care physicians and other health-care providers should bear in mind that DENV-4 can also result in severe forms of the disease and lead to hemorrhagic complications and death, mainly when dengue infection is associated with coexisting conditions.  相似文献   
94.
95.
ABSTRACT: BACKGROUND: The aim of this study was to determine the acute effects of exercise intensity on anxiety, mood states and hunger in obese adolescents. METHODS: Subjects were eight male obese adolescents (age 15.44 +/- 2.06y; BMI 33.06 +/- 4.78 kg/m2). Each subject underwent three experimental trials: 1) Control, seated for 30 min; 2) Low intensity exercise (LIE) - exercise at 10% below ventilatory threshold (VT); 3) High intensity exercise (HIE) - exercise at 10% above VT. Anxiety (STAI Trait/State), mood (POMS) and hunger (VAS) were assessed before and immediately after the experimental sessions. Comparisons between trials and times were assessed using Kruskal-Wallis and Wilcoxon tests, respectively. Associations between variables were described using a Spearman test. RESULTS: The largest increase in hunger was observed after LEI (914.22%). Both exercise sessions increased anxiety, fatigue and decreased vigor (p < 0.05). CONCLUSIONS: Acute exercise bouts are associated with negative changes in anxiety and mood, and with increases in hunger in obese adolescents.  相似文献   
96.
97.
Some cancers like melanoma and pancreatic and ovarian cancers, for example, commonly display resistance to chemotherapy, and this is the major obstacle to a better prognosis of patients. Frequently, literature presents studies in monolayer cell cultures, 3D cell cultures or in vivo studies, but rarely the same work compares results of drug resistance in different models. Several of these works are presented in this review and show that usually cells in 3D culture are more resistant to drugs than monolayer cultured cells due to different mechanisms. Searching for new strategies to sensitize different tumors to chemotherapy, many methods have been studied to understand the mechanisms whereby cancer cells acquire drug resistance. These methods have been strongly advanced along the years and therapies using different drugs have been increasingly proposed to induce cell death in resistant cells of different cancers. Recently, cancer stem cells (CSCs) have been extensively studied because they would be the only cells capable of sustaining tumorigenesis. It is believed that the resistance of CSCs to currently used chemotherapeutics is a major contributing factor in cancer recurrence and later metastasis development. This review aims to appraise the experimental progress in the study of acquired drug resistance of cancer cells in different models as well as to understand the role of CSCs as the major contributing factor in cancer recurrence and metastasis development, describing how CSCs can be identified and isolated.  相似文献   
98.
Cancer is the third most frequent cause of death in children in Brazil. Early diagnosis and medical advances have significantly improved treatment outcomes, which has resulted in higher survival rates and the management of late side effects has become increasingly important in caring for these patients. Dental abnormalities are commonly observed as late effects of antineoplastic therapy in the oral cavity. The incidence and severity of the dental abnormalities depend on the child''s age at diagnosis and the type of chemotherapeutic agent used, as well as the irradiation dose and area. The treatment duration and aggressivity should also be considered. Disturbances in dental development are characterized by changes in shape, number and root development. Enamel anomalies, such as discoloration, opacities and hypoplasia are also observed in these patients. When severe, these abnormalities can cause functional and esthetic sequelae that have an impact on the children''s and adolescents'' quality of life. General dentists and pediatric dentists should understand these dental abnormalities and how to identify them aiming for early diagnosis and appropriate treatment.  相似文献   
99.
100.
The proper disposal of electrical and electronic waste is currently a concern of researchers and environmental managers not only because of the large volume of such waste generated, but also because of the heavy metals and toxic substances it contains. This study analyzed printed circuit boards (PCBs) from discarded computers to determine their metal content and characterized them as solid waste and fuel. The analysis showed that PCBs consist of approximately 26% metal, made up mainly of copper, lead, aluminum, iron and tin, as well as other heavy metals such as cadmium and nickel. Comparison with the results of other studies indicated that the concentration of precious metals (gold and silver) has declined over time. Analysis of the leachate revealed high concentrations of cadmium and lead, giving the residue the characteristics of hazardous waste. After milling the PCBs, we found that larger amounts of metal were concentrated in smaller fractions, while the lightest fraction, obtained by density separation, had a gross calorific value of approximately 11 MJ/kg, although with a high ash content. Milling followed by density separation proved potentially useful for recovery of metals and energy-rich fractions.  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