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   6757篇
  免费   187篇
  国内免费   20篇
耳鼻咽喉   201篇
儿科学   267篇
妇产科学   368篇
基础医学   1031篇
口腔科学   93篇
临床医学   362篇
内科学   1222篇
皮肤病学   112篇
神经病学   474篇
特种医学   144篇
外科学   759篇
综合类   28篇
一般理论   1篇
预防医学   534篇
眼科学   277篇
药学   796篇
中国医学   6篇
肿瘤学   289篇
  2023年   24篇
  2022年   93篇
  2021年   175篇
  2020年   65篇
  2019年   107篇
  2018年   162篇
  2017年   122篇
  2016年   135篇
  2015年   159篇
  2014年   225篇
  2013年   278篇
  2012年   465篇
  2011年   495篇
  2010年   236篇
  2009年   161篇
  2008年   324篇
  2007年   322篇
  2006年   408篇
  2005年   357篇
  2004年   418篇
  2003年   356篇
  2002年   316篇
  2001年   163篇
  2000年   189篇
  1999年   128篇
  1998年   37篇
  1997年   20篇
  1992年   29篇
  1991年   64篇
  1990年   79篇
  1989年   62篇
  1988年   67篇
  1987年   47篇
  1986年   62篇
  1985年   58篇
  1984年   34篇
  1983年   34篇
  1980年   20篇
  1979年   38篇
  1978年   32篇
  1977年   25篇
  1976年   27篇
  1975年   46篇
  1974年   30篇
  1973年   23篇
  1971年   18篇
  1970年   22篇
  1969年   23篇
  1967年   21篇
  1966年   23篇
排序方式: 共有6964条查询结果,搜索用时 15 毫秒
81.
82.
The physico-chemical water characteristics and basin morphology of 10 well-preserved Pomeranian peatland lakes were examined. These are acidic (pH 3.95–5.99), softwater (1.5 ±0.9 mg Ca dm?3), and oligotrophic water bodies. Their hydrochemical conditions differentiate them into two groups: poor (3.04 ±2.77 mg C dm?3) and rich (10.36 ±7.27 mg C dm?3) in organic carbon compounds. They differ in water colour (p = 0.02), humic acid concentration (p<0.001), redox potential (p = 0.007), and irradiance (PAR; p = 0.03). The hydrochemistry of the lakes is determined by their basin morphology, which affects the water colour and the concentrations of humic acids and organic carbon compounds.  相似文献   
83.
Body composition and body mass are pivotal clinical endpoints in studies of welfare diseases. We present a combined effort of established and new mathematical models based on rigorous monitoring of energy intake (EI) and body mass in mice. Specifically, we parameterize a mechanistic turnover model based on the law of energy conservation coupled to a drug mechanism model. Key model variables are fat-free mass (FFM) and fat mass (FM), governed by EI and energy expenditure (EE). An empirical Forbes curve relating FFM to FM was derived experimentally for female C57BL/6 mice. The Forbes curve differs from a previously reported curve for male C57BL/6 mice, and we thoroughly analyse how the choice of Forbes curve impacts model predictions. The drug mechanism function acts on EI or EE, or both. Drug mechanism parameters (two to three parameters) and system parameters (up to six free parameters) could be estimated with good precision (coefficients of variation typically <20 % and not greater than 40 % in our analyses). Model simulations were done to predict the EE and FM change at different drug provocations in mice. In addition, we simulated body mass and FM changes at different drug provocations using a similar model for man. Surprisingly, model simulations indicate that an increase in EI (e.g. 10 %) was more efficient than an equal lowering of EI. Also, the relative change in body mass and FM is greater in man than in mouse at the same relative change in either EI or EE. We acknowledge that this assumes the same drug mechanism impact across the two species. A set of recommendations regarding the Forbes curve, vehicle control groups, dual action on EI and loss, and translational aspects are discussed. This quantitative approach significantly improves data interpretation, disease system understanding, safety assessment and translation across species.  相似文献   
84.
Type 1 diabetes (T1DM) is an autoimmune disease that requires insulin treatment from the time of diagnosis. Its clinical course depends on both genetic and environmental factors, and the lifestyle of a patient modulates their interaction. The evidence about the influence of lifestyle on the course of T1DM is increasing. In this paper, we present evidence on the relationship between lifestyle parameters and diabetes-related outcomes. We discuss the most commonly addressed factors associated with lifestyle, such as physical activity, nutrition and smoking, and those with sparse evidence in T1DM, such as socioeconomic status, sleep duration, psychological stress and illicit drugs intake.  相似文献   
85.
The identification of a sub-endocardial infarction is of major interest in cardiology. This study evaluates the sensitivity of selected measures to the thickness of such an infarction. Synthetic ultrasonic data (long-axis view) of left ventricular models with inclusions were generated using Field II and meshes obtained from finite-element simulations, which also provided the reference for the estimates obtained from ultrasonic data. The displacements, the first and second component of the principal strain (ε1 and ε2), and several measures derived from these quantities were estimated. All estimates, except for the poorly estimated ε2, exhibited sensitivity to the presence and transmurality of the inclusion. The most sensitive was the gradient of the averaged transmural profiles of ε1, and ε1 averaged over the area corresponding to the transmural inclusion. The inflection point of the ε1 profile shifted toward the outer wall with increasing thickness of the non-transmural inclusion.  相似文献   
86.
87.
PurposeC-kit positive interstitial cells of Cajal (ICCs) play an important role in the regulation of the smooth muscle motility, acting as pacemakers to provide the slow wave activity in various organs. Recent studies have shown that c-kit positive ICCs are widely distributed in the urinary tract of animals and humans. The aim of our study was to examine the distribution of ICCs in the children's neurogenic bladder.MethodsAn immunohistochemical study of specimens obtained from neurogenic urinary bladder (from the trigonum and the corpus) of children with meningomyelocele and during autopsy was performed using antibody against c-kit (CD 117). Histological morphometry of immunoexpression of c-kit positive ICCs was performed by means of an image analyzing system.ResultsOur investigation demonstrated ICCs located in the vesical muscle layers. The distribution of those cells is different in the trigonum and the corpus of the urinary bladder. No remarkable differences were observed in c-kit immunoexpression between the neurogenic and the control group.ConclusionThere was no difference in the distribution of ICCs in the urinary bladder of healthy children as compared to children with myelomeningocele. Biopsy revealed different distribution of ICCs in particular parts of the bladder (trigonum/corpus) in both groups of children.  相似文献   
88.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder afflicting about one in every 68 children. It is behaviorally diagnosed based on a triad of symptoms, including impairment in communication, impairment in sociability and abnormal and stereotypic behavior. The subjectivity of behavioral diagnosis urges the need for clinical biomarker tests to improve and complement ASD diagnosis and treatment. Over the past two decades, researchers garnered a broad range of biomarkers associated with ASD and often correlating with the severity of ASD, which includes metabolic and genetic biomarkers or neuroimaging abnormalities. Metabolic biomarkers are either involved in key pathways such as a trans-sulfuration pathway or produced due to the derangement of these pathways in the case of oxidative stress. Recent studies reported several genetic abnormalities related to ASD, encompassing various mechanisms, from copy number variations (CNVs) and single nucleotide polymorphisms (SNPs) to chromosomal anomalies. However, it is still premature to consider these genetic variants as true biomarkers for ASD, due to their low reproducibility and regional-specific nature. Herein, we comprehensively review state of the art about major biomarkers reported in ASD and the association of some biomarkers with ASD symptoms and severity. It is important to establish those biomarkers to be able to help in the diagnosis and to optimize the treatment of ASD.  相似文献   
89.
Phenylketonuria (PKU) is an autosomal recessive metabolic disease caused by an error of phenylalanine metabolism. Delayed treatment or treatment performed unsystematically might lead to neurological disorders and progressive intellectual disability. In the Prader-Willi syndrome (PWS) clinical manifestations change with age. Feeding difficulties resulting from the poor suck and hypotonia are typical in the neonatal period and early infancy. As patients grow their activities increase, muscle tone improves, the extreme hyperphagia appears – the main cause of obesity. Mental development of patients is usually mildly retarded. We report the case of a patient affected by two genetic diseases: PKU and PWS. Variety of clinical symptoms and abnormal results of laboratory analyses make the correct diagnosis difficult. Elevated phenylalanine level in screening newborn test, disorders of muscle tone, poor suck, and low urine biopterin concentration did not allow to clearly rule out the hyperphenylalaninemia caused by a tetrahydrobiopterin deficiency (BH4). Data from obstetric anamnesis and the early postnatal clinical findings suggested the PWS. Hyperphagia and the increased risk of carbohydrates tolerance disorders in patients with PWS make it very difficult to balance properly the low-phenylanine diet necessary in PKU treatment. The patient presented by us needs well-coordinated multidisciplinary medical care which aims to provide proper physical development and to support the boy's mental potential as well as appropriate functioning in the society.  相似文献   
90.
Bronchial asthma is the most common chronic disease in children of developmental age. Data from the auxological literature indicate that children with disturbances in growth may also suffer from atopic disorders. The aim of the present study was to evaluate somatic growth in children with bronchial asthma using anthropological methods. The study was carried out using anthropometric measurements and information on the severity and course of the disease on 261 children with bronchial asthma. Mean body height was lower than in healthy peers and about 5% of subjects were short. Mean BMI and skinfold thicknesses were significantly higher and lean body mass was lower in the study group. Seventeen percent of the children were overweight or obese, and 8% were underweight. Body build was more robust in the girls examined. Longitudinal studies will help determine to what degree the disease itself directly affects physical development, and to what degree treatment does.  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