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   15804篇
  免费   1050篇
  国内免费   60篇
耳鼻咽喉   166篇
儿科学   429篇
妇产科学   206篇
基础医学   1969篇
口腔科学   369篇
临床医学   1556篇
内科学   3662篇
皮肤病学   289篇
神经病学   1642篇
特种医学   467篇
外科学   2162篇
综合类   189篇
一般理论   14篇
预防医学   1497篇
眼科学   438篇
药学   916篇
中国医学   11篇
肿瘤学   932篇
  2023年   88篇
  2022年   134篇
  2021年   345篇
  2020年   185篇
  2019年   324篇
  2018年   350篇
  2017年   286篇
  2016年   265篇
  2015年   320篇
  2014年   498篇
  2013年   665篇
  2012年   1161篇
  2011年   1169篇
  2010年   648篇
  2009年   597篇
  2008年   1069篇
  2007年   1201篇
  2006年   1139篇
  2005年   1111篇
  2004年   1080篇
  2003年   940篇
  2002年   910篇
  2001年   118篇
  2000年   107篇
  1999年   125篇
  1998年   192篇
  1997年   136篇
  1996年   101篇
  1995年   106篇
  1994年   90篇
  1993年   98篇
  1992年   83篇
  1991年   57篇
  1990年   48篇
  1989年   59篇
  1988年   46篇
  1987年   46篇
  1986年   62篇
  1985年   64篇
  1984年   86篇
  1983年   84篇
  1982年   92篇
  1981年   103篇
  1980年   92篇
  1979年   34篇
  1978年   52篇
  1977年   34篇
  1976年   40篇
  1975年   37篇
  1974年   36篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Four children with panic disorder, two boys and two girls between the ages of nine and 16 years, are discussed. They presented with complaints suggesting neurological disorder: 'dizziness', headache, episodic anxiety and 'blackout spells'. Neurological examinations and investigations were normal. Depression and/or anxiety were prominent in all cases. Drug treatment and psychotherapy were of some benefit. Four other children with attention deficit disorders are presented, whose mothers have panic disorder. This association points towards common biochemical influences and suggests that tricyclic drugs may be preferable to CNS stimulants as a form of treatment.  相似文献   
22.
Impaired ability to conduct daily activities is a diagnostic criterion for dementia and a determinant of healthcare services utilization and caregiver burden. What predicts decline in instrumental activities of daily living (IADLs) is not well understood. This study examined measures of episodic memory, executive function, and MRI brain volumes in relation to baseline IADLs and as predictors of rate of IADL change. Participants were 124 elderly persons with cognitive function between normal and moderate dementia both with and without significant small vessel cerebrovascular disease. Random effects modeling showed that baseline memory and executive function (EXEC) were associated with baseline IADL scores, but only EXEC was independently associated with rate of change in IADLs. Whereas hippocampal and cortical gray matter volumes were significantly associated with baseline IADL scores, only hippocampal volume was associated with IADL change. In a model including cognitive and neuroimaging predictors, only EXEC independently predicted rate of decline in IADL scores. These findings indicate that greater executive dysfunction at initial assessment is associated with more rapid decline in IADLs. Perhaps executive function is particularly important with respect to maintaining IADLs. Alternatively, executive dysfunction may be a sentinel event indicating widespread cortical involvement and poor prognosis.  相似文献   
23.
Attention-deficit/hyperactivity disorder (ADHD) is associated with impairments in occupational, social, and educational functioning in adults. This study examined relations of adaptive impairment to ADHD symptom domains (inattentive-disorganized and hyperactive-impulsive) and to deficits in executive functioning (EF) in 195 well-characterized adults (105 ADHD, 90 non-ADHD, between ages 18 and 37). Participants completed a battery of EF measures as well as assessments of adaptive functioning. Confirmatory factor analyses were used to validate latent factors for adaptive functioning and EF. In a measurement model, weaker EF was associated with poorer adaptive functioning (r = -.30). When multi-informant composite variables for current inattentive-disorganized and hyperactive-impulsive ADHD symptoms were included in the structural model, EF no longer predicted adaptive functioning. While both symptom composites were similarly related to EF (inattentive-disorganized r = .36; hyperactive-impulsive r = .29), inattentive-disorganized symptoms accounted for more variance in adaptive functioning (67.2% vs. 3.6%). Furthermore, for retrospectively reported childhood symptoms of ADHD, only the inattentive-disorganized symptom domain was related to EF or adaptive impairment. These results suggest that, in adults with ADHD, inattentive-disorganized symptoms may be the primary contributor to key aspects of poorer adaptive function and may be the behavioral path through which EF deficits lead to adaptive impairment.  相似文献   
24.
Joel Haycock 《Death Studies》1991,15(5):417-433
Suicide in jails is a growing public health problem. It is growing because the suicide rate among young men has increased sharply in the last 20 years and because the recent historic increases in the U.S. rate of jail incarceration have put more and more men, young and old, behind bars. This article reviews the empirical studies resulting from the new attention given jail-suicide research and prevention in the last decade. The author argues that the findings of this literature need to be treated with great caution. The second part of the article considers explanations of the greater risks for completed suicides in jail. The causes for the high rate of jail suicide must lie in the types of people who find themselves in jail (“importation” explanations) or in what jails are like (“deprivation” explanations). A large number of the risk factors for completed and attempted suicide in the general population are overrepresented among jail populations, and the article reviews some of these risk factors. Although this importation case has merit, it is only a partial explanation for the high rate of jail suicide. In contradiction to the assumptions of stricter importation theorists, newer, non-suicide-related research on jail populations has strongly indicated that some part of the elevated rates of inmate distress may be attributed to the effects of exposure to jail environments. The author concludes that new studies notwithstanding, the empirical research base on jail suicide remains very limited. Several avenues for new investigations are suggested.  相似文献   
25.
26.
27.
28.
Age and gender interactions on verbal memory performance.   总被引:1,自引:0,他引:1  
Age and gender effects on verbal episodic memory are well established. However, the possibility of interactions between age and gender has been raised by studies linking estrogen and verbal memory performance, and by research suggesting gender differences in age-related cortical atrophy. We evaluated whether age by gender interactions in verbal memory were present. Subjects within three years of the median age of menopause were excluded from a large cohort of normal subjects, resulting in a younger sample (16-47 years) of 288 men and 285 women, and an older sample (55-89 years) of 201 men and 245 women. All subjects were administered the CVLT-2, a multiple-trial list-learning task. Verbal memory was negatively correlated with age for younger men, older men, and older women, but not for younger women. Multivariate analyses indicated age by gender interactions on memory for the younger group but not the older group. Results indicate that verbal memory declines with age for younger men but not younger women, whereas both older men and older women show age-related declines. These findings are consistent with hypotheses linking estrogen and verbal memory performance, and with imaging data suggesting that age-related hippocampal atrophy is found in younger men but not younger women. The role of estrogen on cognition in normal aging warrants further study.  相似文献   
29.
Introduction: Opioid-induced rigidity often makes bag-mask ventilation difficult or impossible during induction of anesthesia. Difficult ventilation may result from chest wall rigidity, upper airway closure, or both. This study further defines the contribution of vocal cord closure to this phenomenon.

Methods: With institutional review board approval, 30 patients undergoing elective cardiac surgery participated in the study. Morphine (0.1 mg/kg) and scopolamine (6 micro gram/kg) given intramuscularly provided sedation along with intravenous midazolam as needed. Lidocaine 10% spray provided topical anesthesia of the oropharynx. A fiberoptic bronchoscope positioned in the airway photographed the glottis before induction of anesthesia. A second photograph was obtained after induction with 3 micro gram/kg sufentanil administered during a period of 2 min. A mechanical ventilator provided 10 ml/kg breaths at 10/min via mask and oral airway with jaw thrust. A side-stream spirometer captured objective pulmonary compliance data. Subjective airway compliance was scored. Pancuronium (0.1 mg/kg) provided muscle relaxation. One minute after the muscle relaxant was given, a third photograph was taken and compliance measurements and scores were repeated. Photographs were scored in a random, blinded manner by one investigator. Wilcoxon signed rank tests compared groups, with Bonferroni correction. Differences were considered significant at P <0.05.

Results: Twenty-eight of 30 patients exhibited decreased pulmonary compliance and closed vocal cords after opioid induction. Two patients with neither objective nor subjective changes in pulmonary compliance had open vocal cords after opioid administration. Both subjective and objective compliances increased from severely compromised values after narcotic-induced anesthesia to normal values (P = 0.000002) after patients received a relaxant. Photo scores document open cords before induction, progressing to closed cords after the opioid (P = 0.00002), and opening again after a relaxant was administered (P = 0.00005).  相似文献   

30.
BACKGROUND AND OBJECTIVE: In recent years, new classes of medication, such as the serotonin-noradrenaline reuptake inhibitors (SNRIs), have been developed for use in the treatment of major depressive disorder (MDD). For many years, treatment options were largely limited to the use of monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). However, there have been published reports of orthostatic hypotension, arrhythmias and corrected QT (QTc) interval changes in patients treated with TCAs. As new medications become available, it is important to understand how their cardiovascular safety profile compares with that of more established agents to aid clinicians and patients in choosing the best treatment options. This study was designed to evaluate the cardiovascular safety profile of the SNRI duloxetine through evaluation of cardiovascular-related parameters and adverse events (AEs). METHODS: The cardiovascular safety of duloxetine was assessed using all placebo-controlled duloxetine clinical trial data as of December 2005. This consisted of data from 42 placebo-controlled clinical trials of 8504 patients who were treated with duloxetine. Additional information from a high-dose clinical pharmacology study and postmarketing safety surveillance are also presented. Of the placebo-controlled trials included in this analysis, clinical indications under investigation included MDD (15 studies), diabetic peripheral neuropathic pain (3 studies), fibromyalgia (2 studies), generalised anxiety disorder (3 studies) and lower urinary tract disorders (19 studies, all related to incontinence). Cardiovascular safety was evaluated based on vital signs, ECGs and the incidence of treatment-emergent AEs potentially related to cardiovascular safety. These safety parameters were analysed across all indications. To identify both serious and non-serious cardiovascular-related AEs, as well as AEs reported as the reason for discontinuation, a comprehensive list of terms derived from the Medical Dictionary for Regulatory Activities (version 8.0) was generated and used to search the duloxetine databases for cardiovascular-related events. RESULTS: Calculation of change from baseline to maximum in ECG parameters showed significant differences between treatment groups for all parameters, with decreases from baseline in RR, QRS and QT intervals for patients receiving duloxetine and increases from baseline for patients treated with placebo. These shifts were related to small heart rate changes, but the mean differences were not considered clinically relevant. Categorical analyses of shifts from normal to abnormal (or abnormal to normal) for heart rate and QT corrected for heart rate using Fridericia's formula (QTcF) values showed that most patients did not shift from their baseline category. Patients with MDD who were treated for up to 1 year with duloxetine had blood pressure changes early in treatment that then stabilised. Even in patients with elevated blood pressure at baseline in these clinical trials, no increased risk of sustained blood pressure elevation with duloxetine treatment was found. CONCLUSION: Overall, the findings presented here support our conclusions that use of duloxetine does not appear to be associated with significant cardiovascular risks in patients with conditions for which the drug has been approved or studied.  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