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   41375篇
  免费   2807篇
  国内免费   150篇
耳鼻咽喉   262篇
儿科学   1432篇
妇产科学   935篇
基础医学   4782篇
口腔科学   770篇
临床医学   4384篇
内科学   8807篇
皮肤病学   736篇
神经病学   4006篇
特种医学   1363篇
外国民族医学   1篇
外科学   6302篇
综合类   680篇
一般理论   60篇
预防医学   3366篇
眼科学   1046篇
药学   2900篇
中国医学   41篇
肿瘤学   2459篇
  2023年   149篇
  2022年   272篇
  2021年   622篇
  2020年   396篇
  2019年   657篇
  2018年   791篇
  2017年   626篇
  2016年   633篇
  2015年   805篇
  2014年   1159篇
  2013年   1764篇
  2012年   2696篇
  2011年   2887篇
  2010年   1638篇
  2009年   1496篇
  2008年   2644篇
  2007年   2885篇
  2006年   2831篇
  2005年   2919篇
  2004年   2747篇
  2003年   2532篇
  2002年   2533篇
  2001年   448篇
  2000年   282篇
  1999年   427篇
  1998年   629篇
  1997年   465篇
  1996年   430篇
  1995年   365篇
  1994年   310篇
  1993年   320篇
  1992年   283篇
  1991年   244篇
  1990年   227篇
  1989年   227篇
  1988年   199篇
  1987年   175篇
  1986年   201篇
  1985年   201篇
  1984年   294篇
  1983年   251篇
  1982年   313篇
  1981年   281篇
  1980年   283篇
  1979年   162篇
  1978年   155篇
  1977年   156篇
  1976年   136篇
  1974年   132篇
  1973年   121篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
In the emergency department, photography requires an expedient, portable, adaptable, and relatively simple camera system to take advantage of fleeting opportunities for recording visually educational material. These prerequisites are different from those for traditional medical photography, for which relatively plentiful time and advanced equipment are routinely available. Medical photography departments provide an invaluable service, but are rarely convenient for immediate or spontaneous emergency. department photographs. Although no single system or technique is optimal in all these areas, the authors find certain components and approaches work well. They review photographic equipment, paying attention to speed, ease of use, and quality of output. They also review simple techniques such as film choice, lighting, close-up photography, standardization, copy work, and radiographs. Attention to these details can help the inexperienced photographer obtain a system and begin to enjoy the rewards of effective photography in the emergency department.  相似文献   
82.
Reference data files support the evaluation of myocardial perfusion single-photon emission tomography (SPET). The aim of this study was to create a large reference data base for technetium-99m sestamibi SPET, age and gender matched to the general patient population. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a likelihood of coronary artery disease of less than 5% underwent rest and maximal exercise99mTc-sestamibi SPET with a 2-day protocol and 180° elliptical rotation. The normalized activity values of99mTc-sestamibi in the inferior wall differed significantly between men and women. Age variations were found for men in the anterior wall. Normalized activity values in all four walls were strikingly similar during rest and stress. Our results suggest that the use of reference files in99mTc-sestamibi SPET requires a gender- and, for males, possibly an age-matched reference population. Different reference files at rest and during stress might not be necessary.  相似文献   
83.
Previous studies have suggested that corticotropin-releasing factor (CRF) has immunoregulatory effects in addition to its neuroendocrine role. We examined the ability of CRF to inhibit lipopolysaccharide (LPS)-induced pulmonary vascular leak in vivo. Female BALB/C mice were treated with either normal saline (NS) or CRF prior to injection with LPS. Pulmonary vascular leak was inhibited by CRF as assessed by measurement of lung wet-to-dry ratios. The stress-induced increase in serum corticosterone levels in mice injected with LPS alone was not further increased by treatment with CRF. This indicates that the effect of CRF was not mediated centrally by stimulation of endogenous steroid release. Histologic examination of the lungs revealed that leukocyte infiltration was significantly depressed in CRF-treated mice thus confirming the protective effect of CRF. In addition, a modest prolongation of survival was demonstrated in CRF-treated mice following challenge with LPS (p=.08). These data indicate the potential utility of CRF as a modulator of pulmonary vascular leak.  相似文献   
84.
The present study evaluated curiosity and anger as motives among childhood firesetters. Parents of 133 firesetters (ages 6-13) completed the Fire Incident Analysis (FIA) to permit classification of the children as high and low on each of these two primary motives and to document details of the child's most serious incident within the past 12 months. The children were compared on measures of child dysfunction and firesetting history. An effect of Curiosity was found on measures of psychopathology, firesetting risk, and fire involvement, whereas an effect of Anger was found on measures of firesetting risk and the behavioral correlates of individual incidents. The results clarify the role of child motive in understanding firesetting involvement.  相似文献   
85.
The opioid transmitters enkephalin and dynorphin are known to regulate pallidal output and consequently cortical excitability. Indeed, abnormal basal ganglia opioid transmission has been reported in several involuntary movement disorders, including levodopa-induced dyskinesias in Parkinson's disease (PD), tardive dyskinesias/dystonia, Huntington's disease, and Tourette's syndrome. Moreover, a previous 11C-diprenorphine PET study investigating levodopa-induced dyskinesias found reduced opioid receptor availability in PD with but not without dyskinesias. We wished to investigate if a similar alteration in basal ganglia opioid binding was present in DYT1 primary torsion dystonia (PTD). Regional cerebral 11C-diprenorphine binding was investigated in 7 manifesting carriers of the DYT1 gene and 15 age-matched normal controls using a region-of-interest (ROI) approach and statistical parametric mapping (SPM). No difference in regional mean 11C-diprenorphine binding was found between DYT1-PTD and controls, and no correlation between the severity of dystonia and opioid binding was seen. We conclude that aberrant opioid transmission is unlikely to be present in DYT1-PTD and altered opioid transmission is not a common mechanism underlying all disorders of involuntary movement.  相似文献   
86.
OBJECTIVE: The primary purpose of this study was to compare parent and teacher reports of executive function (EF), as measured by the Behavior Rating Inventory of Executive Function (BRIEF), on a sample of children who had been diagnosed with attention-deficit hyperactivity disorder (ADHD). If differences were found, the secondary purpose was to explore these differences by determining which of the 8 BRIEF scales, each representing a different EF, would best predict symptoms of ADHD by the 2 proxy reporters. METHOD: We performed a secondary data analysis on the assessment information pertaining to 240 children, aged 5 to 15 years, accessing services at an urban Toronto psychiatric program specializing in ADHD. We compared parent and teacher ratings and applied logistical binary regressions to predict the probability of a child's meeting the criteria for clinically significant inattention and hyperactivity-impulsivity on the ADHD Rating Scale-IV. RESULTS: As expected, teachers reported more variety and severity of EF impairments than did parents. In addition, teachers used inhibition, organization of materials, and planning and organizing as predictors of ADHD symptoms, whereas parents relied predominantly on inhibition, working memory, and planning and organizing as the risk factors. CONCLUSION: Consistent with the current theory, EF impairments, particularly in inhibition, appear to underlie the behavioural manifestation of ADHD. However, parents and teachers do not always agree when reporting EF impairments at home and in school. Thus information from both types of informants is essential for understanding and treating children with this disorder.  相似文献   
87.
88.
一个新的研究提出,喝下一杯酸果汁将大大地推进卵巢癌病人对化学疗法的敏感性。研究人员说,在实验室实验中,用果汁来预处理卵巢癌细胞将把药物的杀伤力骤然提升6倍。研究员强调这个发现还是实验结果也只是初步结果,但它给已经开始抵抗治疗的卵巢肿瘤病人提供了一种新选择。  相似文献   
89.
Rectal administration of diazepam is highly effective in terminating absence status as judged by reduction of spike-wave activity in the EEG. Pharmacokinetic studies indicate that diazepam can have antiepileptic properties at serum levels well below those previously reported as being necessary to achieve a therapeutic effect.  相似文献   
90.
ABSTRACT: The role public elementary schools have in educating children about hearing and hearing conservation is underscored by the high incidence of hearing loss in society and by the deleterious effect on communication and learning that hearing impairment causes in children. A survey to assess the extent and estimated effectiveness of the education regarding hearing and hearing conservation provided to children was conducted. One hundred sixty regular elementary school teachers returned a questionnaire, and their responses revealed that hearing and hearing conservation concepts were being taught in most classrooms. However, their responses questioned the effectiveness of the methods and materials used to teach these concepts. The findings of the survey suggest three ways to improve teaching in this area: provide in-depth instruction about the causes of hearing impairment; use more hands-on activities; and provide teachers with more resources to supplement instruction.  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