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   56254篇
  免费   3990篇
  国内免费   118篇
耳鼻咽喉   485篇
儿科学   2038篇
妇产科学   1871篇
基础医学   6706篇
口腔科学   691篇
临床医学   9513篇
内科学   10426篇
皮肤病学   889篇
神经病学   4925篇
特种医学   1067篇
外国民族医学   33篇
外科学   5247篇
综合类   653篇
一般理论   80篇
预防医学   7524篇
眼科学   715篇
药学   3431篇
  1篇
中国医学   140篇
肿瘤学   3927篇
  2023年   382篇
  2022年   643篇
  2021年   1321篇
  2020年   846篇
  2019年   1297篇
  2018年   1476篇
  2017年   1014篇
  2016年   1139篇
  2015年   1233篇
  2014年   1678篇
  2013年   2708篇
  2012年   3853篇
  2011年   4067篇
  2010年   2165篇
  2009年   2036篇
  2008年   3555篇
  2007年   4016篇
  2006年   3845篇
  2005年   3748篇
  2004年   3567篇
  2003年   3412篇
  2002年   3205篇
  2001年   541篇
  2000年   419篇
  1999年   529篇
  1998年   704篇
  1997年   570篇
  1996年   486篇
  1995年   386篇
  1994年   389篇
  1993年   378篇
  1992年   303篇
  1991年   267篇
  1990年   274篇
  1989年   209篇
  1988年   199篇
  1987年   215篇
  1986年   180篇
  1985年   208篇
  1984年   231篇
  1983年   223篇
  1982年   272篇
  1981年   251篇
  1980年   197篇
  1979年   140篇
  1978年   123篇
  1977年   136篇
  1976年   114篇
  1975年   94篇
  1973年   93篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
The World Wide Web creates new challenges and opportunities for medical educators. Prominent among these are the lack of consistent standards by which to evaluate web-based educational tools. We present the instrument that was used to review web-based innovations in medical education submissions to the 2003 Society of General Internal Medicine (SGIM) national meeting, and discuss the process used by the SGIM web-based clinical curriculum interest group to develop the instrument. The 5 highest-ranked submissions are summarized with commentary from the reviewers.  相似文献   
102.
Information about how Thai school-age children perceive fear is necessary for the development of culturally appropriate anxiety or fear measures. The purpose of this study was to describe Thai school-age children's perceptions of fear from their own perspective. Qualitative data from 13 Thai students in Grades 3 to 6 in three schools in Bangkok were obtained by semistructured, formal interviews, combined with drawings. The data were analyzed using content analysis within the frame of category development in the grounded theory method. Several culturally specific aspects of fear were revealed. This information is useful for health care providers caring for Thai children. The results of this study also illustrate the importance of carefully assessing children from culturally diverse backgrounds related to manifestations of anxiety or fear.  相似文献   
103.
Corticotropin-releasing hormone receptor type 1 (CRH-R1)-deficient mice display reduced anxiety-like behavior, a chronic corticosterone deficit, and an impaired neuroendocrine stress response caused by disruption of the hypothalamic-pituitary-adrenocortical (HPA) axis. The molecular substrates and pathways of CRH/CRH-R1-dependent signaling mechanisms underlying the behavioral phenotype as well as the consequences of lifelong glucocorticoid deficit remain largely obscure. To dissect involved neuronal circuitries, we performed comparative expression profiling of brains of CRH-R1 mutant and wild-type mice using our custom made MPIP (Max Planck Institute of Psychiatry) 17k cDNA microarray. Microarray analysis yielded 107 genes showing altered expression levels when comparing CRH-R1 knockout mice with wild-type littermates. A significant proportion of differentially expressed genes was related to control of HPA and hypothalamic-pituitary-thyroid (HPT) axes reflecting not only the disturbance of the HPA axis in CRH-R1 mutant mice but also the interplay of both neuroendocrine systems. The spatial analysis of regulated genes revealed a prevalence for genes expressed in the cerebral microvasculature. This phenotype was confirmed by the successful cross-validation of regulated genes in CRH overexpressing mice. Analysis of the cerebral vasculature of CRH-R1 mutant and CRH overexpressing mice revealed alterations of functional rather than structural properties. A direct role of the CRH/CRH-R1 system was supported by demonstrating Crhr1 expression in the adult murine cerebral vasculature. In conclusion, these data suggest a novel, previously unknown role of the CRH/CRH-R1 system in modulating neurovascular gene expression and function.  相似文献   
104.
105.
106.
Preoperative cytologic examinations were performed on bronchial material from 92 patients with postsurgical (pathologic) stage I (American Joint Committee) adenocarcinoma of the lung. All patients were followed up for at least 5 years or until death; thus, cases of adenocarcinoma metastatic to the lungs were virtually excluded. Only 22 patients (24%) had abnormal preoperative cytologic findings. This low cytologic sensitivity is ascribed to the small size and peripheral location of the tumors. Large lesions of high histologic grades were more likely to have positive preoperative cytologic findings than small, well-differentiated ones.  相似文献   
107.
INTRODUCTION: A torn labial frenum is widely regarded as pathognomonic of abuse. METHODS: We systematically reviewed the evidence for this, and to define other intra-oral injuries found in physical abuse. Nine studies documented abusive torn labial frena in 27 children and 24 [corrected] were fatally abused: 22 were less than 5 years old. Only a direct blow to the face was substantiated as a mechanism of injury. RESULTS: Two studies noted accidentally torn labial frena, both from intubation. Abusive intra-oral injuries were widely distributed to the lips, gums, tongue and palate and included fractures, intrusion and extraction of the dentition, bites and contusions. CONCLUSIONS: Current literature does not support the diagnosis of abuse based on a torn labial frenum in isolation. The intra-oral hard and soft tissue should be examined in all suspected abuse cases, and a dental opinion sought where abnormalities are found.  相似文献   
108.
Summary A variety of methods are now available for the preparation and labelling of viral nucleic acids for use as probes in diagnostic virology. Some of these are assessed including the use of synthetic oligonucleotides in place of molecularly cloned nucleic acids, and alternatives to labelling with radioactive isotopes such as biotin, enzymes and fluorochromes. Dot blot, sandwich, indirect sandwich and in situ hybridization are covered, and examples given of the current use of nucleic acid probes in detection of human viral infections. The potential and limitations of nucleic acid hybridization are discussed in the light of these new methods.  相似文献   
109.
Existing evidence suggests an excess of winter births in schizophrenia and inconsistent results for other psychiatric conditions. The present study examined seasonal effects of birth among autistic individuals. Results revealed an excess of spring and carly summer births and an underrepresentation of winter and fall births. However, this pattern was obtained only for the male, nonverbal, and lower-functioning autistic subgroup.This project was supported in part by the Ontario Mental Health Foundation Grant #988-84/86.  相似文献   
110.
Traditionally, neuropsychological deficits due to Sickle Cell Disease (SCD) have been understudied in adults. We have begun to suspect, however, that symptomatic and asymptomatic Cerebrovascular Events (CVE) may account for an alarming number of deficits in this population. In the current brief review, we critically evaluated the pediatric and adult literatures on the neurocognitive effects of SCD. We highlighted the studies that have been published on this topic and posit that early detection of CVE via neurocognitive testing, neuropsychiatric evaluations, and neuroimaging may significantly reduce adult cognitive and functional morbidities.  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