全文获取类型
收费全文 | 1485篇 |
免费 | 102篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 56篇 |
儿科学 | 62篇 |
妇产科学 | 66篇 |
基础医学 | 179篇 |
口腔科学 | 31篇 |
临床医学 | 192篇 |
内科学 | 235篇 |
皮肤病学 | 6篇 |
神经病学 | 241篇 |
特种医学 | 46篇 |
外科学 | 215篇 |
综合类 | 29篇 |
预防医学 | 85篇 |
眼科学 | 40篇 |
药学 | 63篇 |
肿瘤学 | 42篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 36篇 |
2020年 | 18篇 |
2019年 | 27篇 |
2018年 | 35篇 |
2017年 | 24篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 51篇 |
2013年 | 54篇 |
2012年 | 79篇 |
2011年 | 71篇 |
2010年 | 54篇 |
2009年 | 52篇 |
2008年 | 78篇 |
2007年 | 63篇 |
2006年 | 58篇 |
2005年 | 61篇 |
2004年 | 63篇 |
2003年 | 54篇 |
2002年 | 63篇 |
2001年 | 38篇 |
2000年 | 47篇 |
1999年 | 46篇 |
1998年 | 18篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1992年 | 27篇 |
1991年 | 17篇 |
1990年 | 22篇 |
1989年 | 29篇 |
1988年 | 25篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 25篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1975年 | 14篇 |
1974年 | 12篇 |
1973年 | 11篇 |
1972年 | 8篇 |
1971年 | 7篇 |
1969年 | 6篇 |
1931年 | 6篇 |
排序方式: 共有1588条查询结果,搜索用时 31 毫秒
41.
42.
Kelsie Adkisson Katherine C. Cunningham Eric A. Dedert Michelle F. Dennis Patrick S. Calhoun Eric B. Elbogen 《Archives of Suicide Research》2013,17(4):678-687
The objective of the present study was to use retrospective data to test the hypothesis that cannabis dependence would be associated with an increased rate of post-deployment suicide attempts. Participants included 319 veterans who had deployed to either Iraq or Afghanistan. Study procedures involved completion of a structured clinical interview and a battery of self-report questionnaires. As expected, lifetime cannabis dependence was significantly associated with post-deployment suicide attempts, AOR = 7.963, p = .014, even after controlling for the effects of pre-deployment suicide attempts, posttraumatic stress disorder, depression, pain, non-cannabis substance use disorder, and gender. Although preliminary, our findings provide the first evidence to date that heavy cannabis use may be a unique risk factor for post-deployment suicide attempts among veterans. 相似文献
43.
Gierisch JM Bastian LA Calhoun PS McDuffie JR Williams JW 《Journal of general internal medicine》2012,27(3):351-360
OBJECTIVES
We conducted a systematic literature review of smoking cessation interventions for patients with histories of depressive disorders or current significant depressive symptoms. We examined the comparative effectiveness of smoking cessation strategies on abstinence rates, differential effects of cessation strategies by depression status (i.e., history positive vs. current depression), and differential effects by gender. 相似文献44.
Obstructive sleep apnoea (OSA) and hypertension commonly coexist. Observational studies indicate that untreated OSA is strongly associated with an increased risk of prevalent hypertension, whereas prospective studies of normotensive cohorts suggest that OSA may increase the risk of incident hypertension. Randomized evaluations of continuous positive airway pressure (CPAP) indicate an overall modest effect on blood pressure (BP). Determining why OSA is so strongly linked to having hypertension in cross-sectional studies, but yet CPAP therapy has limited BP benefit needs further exploration. The CPAP studies do, however, indicate a wide variation in the BP effects of CPAP, with some patients manifesting a large antihypertensive benefit such that a meaningful BP effect can be anticipated in some individuals. OSA is particularly common in patients with resistant hypertension (RHTN). The reason for this high prevalence of OSA is not fully explained, but data suggest that it may be related to the high occurrence of hyperaldosteronism in patients with RHTN. In patients with RHTN, it has been shown that aldosterone levels correlate with severity of OSA and that blockade of aldosterone reduces the severity of OSA. Overall, these findings are consistent with aldosterone excess contributing to worsening of underlying OSA. We hypothesize that aldosterone excess worsens OSA by promoting accumulation of fluid within the neck, which then contributes to increased upper airway resistance. 相似文献
45.
Acelajado MC Pisoni R Dudenbostel T Dell'Italia LJ Cartmill F Zhang B Cofield SS Oparil S Calhoun DA 《Journal of clinical hypertension (Greenwich, Conn.)》2012,14(1):7-12
Among patients with resistant hypertension (RHTN), there are those whose blood pressure (BP) remains uncontrolled in spite of maximal medical therapy. This retrospective analysis aims to characterize these patients with refractory hypertension. Refractory hypertension was defined as BP that remained uncontrolled after ≥3 visits to a hypertension clinic within a minimum 6-month follow-up period. Of the 304 patients referred for RHTN, 29 (9.5%) remained refractory to treatment. Patients with refractory hypertension and those with controlled RHTN had similar aldosterone levels and plasma renin activity (PRA). Patients with refractory hypertension had higher baseline BP (175±23/97±15 mm Hg vs 158±25/89±15 mm Hg; P=.001/.005) and heart rate, and higher rates of prior stroke and congestive heart failure. During follow-up, the BP of patients with refractory hypertension remained uncontrolled (168.4±14.8/93.8±17.7 mm Hg) in spite of use of an average of 6 antihypertensive medications, while those of patients with controlled RHTN decreased to 129.3±11.2/77.6±10.8 mm Hg. Spironolactone reduced the BP by 12.9±17.8/6.6±13.7 mm Hg in patients with refractory hypertension and by 24.1±16.7/9.2±12.0 mm Hg in patients with controlled RHTN. In patients with RHTN, approximately 10% remain refractory to treatment. Similar aldosterone and PRA levels and a diminished response to spironolactone suggest that aldosterone excess does not explain the treatment failure. 相似文献
46.
RR Pillai R Divekar A Brasier S Bhavnani WJ Calhoun 《Current allergy and asthma reports》2012,12(5):388-395
Asthma is a chronic inflammatory disease of the airways that leads to various degrees of recurrent respiratory symptoms affecting patients globally. Specific subgroups of asthma patients have severe disease leading to increased healthcare costs and socioeconomic burden. Despite the overwhelming prevalence of the asthma, there are limitations in predicting response to therapy and identifying patients who are at increased risk of morbidity. This syndrome presents with common clinical signs and symptoms; however, awareness of subgroups of asthma patients with distinct characteristics has surfaced in recent years. Investigators attempt to describe the phenotypes of asthma to ultimately assist with diagnostic and therapeutic applications. Approaches to asthma phenotyping are multifold; however, it can be partitioned into 2 essential groups, clinical phenotyping and molecular phenotyping. Innovative techniques such as bipartite network analysis and visual analytics introduce a new dimension of data analysis to identify underlying mechanistic pathways. 相似文献
47.
Yoichi Nonaka Takanori Fukushima Kentaro Watanabe Allan H. Friedman John T. McElveen Jr. Calhoun D. Cunningham III Ali R. Zomorodi 《Neurosurgical review》2013,36(4):579-586
For the past three decades, surgery of glomus jugulare tumors (GJTs) has been characterized by extensive combined head and neck, neuro-otologic, and neurosurgical approaches. In recent years, the authors have modified the operative technique to a less invasive approach for preservation of cranial nerves while achieving satisfactory tumor resection. We evaluated and compared the clinical outcomes of our current less invasive approach with our previous more extensive procedures. The clinical records of 39 cases of GJT surgically treated between 1992 and 2011 were retrospectively reviewed. The less invasive transjugular approach with Fallopian bridge technique (LI-TJ) was used for the most recent five cases. The combined transmastoid–transjugular and high cervical (TM-HC) approach was performed in 30 cases, while four cases were treated with a transmastoid–transsigmoid approach with facial nerve translocation. Operative technique, extent of tumor resection, operating time, hospital stay, and morbidity were examined through the operative records, and a comparison was made between the LI-TJ cases and the more invasive cases. No facial nerve palsy was seen in the LI-TJ group while the TM-HC group demonstrated six cases (17.6 %) of facial palsy (House–Brackmann facial nerve function grading scale grade II and III). The complication rate was 0 % in the LI-TJ group and 16.7 % in the more invasive group. The mean operative time and hospital stay were shorter in the LI-TJ group (6.4 h and 4.3 days, respectively) compared with the more invasive group (10.7 h and 8.0 days, respectively). The LI-TJ approach with Fallopian bridge technique provided adequate tumor resection with cranial preservation and definitive advantage over the more extensive approach. 相似文献
48.
Ross S. Chafetz John P. Gaughan Christina Calhoun Jennifer Schottler Lawrence C. Vogel Randal Betz M.J. Mulcahey 《Topics in spinal cord injury rehabilitation》2013,19(1):31-41
Background:
The predictors and patterns of upright mobility in children with a spinal cord injury (SCI) are poorly understood.Objective:
The objective of this study was to develop a classification system that measures children’s ability to integrate ambulation into activities of daily living (ADLs) and to examine upright mobility patterns as a function of their score and classification on the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) exam.Methods:
This is a cross-sectional, multicenter study that used a convenience sample of subjects who were participating in a larger study on the reliability of the ISNCSCI. A total of 183 patients between 5 and 21 years old were included in this study. Patients were asked if they had participated in upright mobility in the last month and, if so, in what environment and with what type of bracing. Patients were then categorized into 4 groups: primary ambulators (PrimA), unplanned ambulators (UnPA), planned ambulators (PlanA), and nonambulators.Results:
Multivariate analyses found that only lower extremity strength predicted being a PrimA, whereas being an UnPA was predicted by both lower extremity strength and lack of preservation of S45 pinprick sensation. PlanA was only associated with upper extremity strength.Conclusions:
This study introduced a classification system based on the ability of children with SCI to integrate upright mobility into their ADLs. Similar to adults, lower extremity strength was a strong predictor of independent mobility (PrimA and UnPA). Lack of pinprick predicted unplanned ambulation, but not being a PrimA. Finally, upper extremity strength was a predictor for planned ambulation.Key words: ambulation, ISNCSCI, pediatrics, spinal cord injuryAfter a spinal cord injury (SCI), learning to walk often becomes the focus of rehabilitation for children and their families.1,2 Although the majority of children with SCI do not return to full-time functional ambulation, those who accomplish some level of walking report positive outcomes such as feeling “normal” again, being eye-to-eye with peers, and having easier social interactions.3 Although not frequently reported by patients, there is some evidence of physiological benefits as well.3–9 Regardless of age, upright mobility has been positively associated with community participation and life satisfaction.10–12 For children, upright mobility allows them to explore their physical environment, which facilitates independence and learning as part of the typical developmental process.13,14With the use of standers, walkers, and other assistive devices, as well as a variety of lower extremity orthoses, it is a reasonable expectation that some children with spinal injuries achieve upright stance and mobility.7,9,13–21 However, there are 2 main challenges for clinicians and patients: understanding the factors that either encourage or discourage upright activities, and identifying how best to determine whether upright mobility is successful and meaningful. The literature on adults suggests that upright mobility is dependent on physiological and psychosocial factors. Physiological factors include the patient’s current age, neurological level, muscle strength, and comorbidities.14,22–27 Psychosocial factors include satisfaction with the appearance of the gait pattern, cosmesis, social support for donning/doffing braces, and assistance with transfer and during ambulation.3,9,19,28–32The identification of outcome measures that provide a meaningful indication of successful upright mobility has been difficult. The World Health Organization (WHO) describes 2 constructs for considering outcomes – capacity and performance.33 Capacity refers to maximal capability in a laboratory setting. An example of a capacity measure is the Walking Index for Spinal Cord Injury (WISCI), which is an ordinal scale used to quantify walking capacity based on assistive device, type of orthosis, and amount of assistance required.34,35 Other capacity measures include the Timed Up and Go test and the 6-minute walk test.36,37 On the other hand, performance refers to actual activity during a patient’s daily activities in typical, real-life environments.33 For example, the FIM is an observation scale that scores the patient’s typical daily performance.36,38–40 The FIM is considered a burden of care measure that determines the amount of actual assistance provided to a patient during typical routines and environments, which may or may not reflect maximal ability or capacity. Performance measures provide an adequate clinical snap-shot of a patients’ daily function (evaluates what they do), whereas capacity measures are better research tools, as they are able to detect subtle changes in ambulation (evaluates what they can do).In children, no capacity outcome measures of ambulation have been tested for validity or reliability. Availability of reliable and valid performance measures is also lacking. The WeeFIM is a performance measure for children, but it is not SCI specific. It is scored on the child’s burden of care, that is, on the maximal assistance required rather than the child’s maximal independence or the highest capacity of performance during a typical day. For children, another commonly used scale is the Hoffer Scale, which relies on the physician’s or therapist’s subjective determination of the purpose of the upright mobility activities (for function or for exercise).41,42 Because parents and school systems are encouraged to integrate “exercise” ambulation into daily activities, it may not be possible to distinguish between therapeutic and functional ambulation in the home, school, or community environments. In the schools, a teacher/therapist should incorporate upright mobility into the classroom setting by donning a child’s braces and then having her/him ambulate a short distance to stand at an easel in art class or to stand upright when talking to friends during recess. In this situation, walking serves the dual purpose of being functional and therapeutic.For this study, it was decided not to rely on a subjective determination of therapeutic versus functional ambulation as the main outcome measure. Instead, we were interested in the children and adolescents who have successfully integrated independent mobility into their daily activities, regardless of frequency, distance, or purpose. Recent literature in studies of children and adolescents suggests that spontaneity is important for participation in functional and social activities. For example, a survey of patients using functional electrical stimulation for hand function found a reduction in the dependence on others for donning splints, which facilitated independence with activities of daily living (ADLs) in adolescents.43–45 In a more recent study, Mulcahey et al46 found that a reduction of spontaneity in adolescents was a barrier for social activity; during cognitive interviews, children reported not participating in sleepovers due to planning their bowel/bladder programs.To date, there are no measures that integrate spontaneity of standing and/or upright mobility into the daily activities of children. Toward that aim, this study introduces a new scale that attempts to categorize children into 4 mutually exclusive groups: primary ambulators, unplanned ambulators, planned ambulators, and nonambulators. The purpose of this study was to examine ambulation patterns among children and adolescents with SCI as a function of neurological level, motor level, and injury severity, as defined by the motor, sensory, and anorectal examinations of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). A secondary aim of the study was to determine how performance on the ISNCSCI exam was associated with the ability of children to independently integrate ambulation into their daily routines. 相似文献49.
Tonya White Stefan Ehrlich Beng-Choon Ho Dara S. Manoach Arvind Caprihan S. Charles Schulz Nancy C. Andreasen Randy L. Gollub Vince D. Calhoun Vincent A. Magnotta 《Schizophrenia bulletin》2013,39(5):1077-1086
There is considerable evidence implicating brain white matter (WM) abnormalities in the pathophysiology of schizophrenia; however, the spatial localization of WM abnormalities reported in the existing studies is heterogeneous. Thus, the goal of this study was to quantify the spatial characteristics of WM abnormalities in schizophrenia. One hundred and fourteen patients with schizophrenia and 138 matched controls participated in this multisite study involving the Universities of Iowa, Minnesota, and New Mexico, and the Massachusetts General Hospital. We measured fractional anisotropy (FA) in brain WM regions extracted using 3 different image-processing algorithms: regions of interest, tract-based spatial statistics, and the pothole approach. We found that FA was significantly lower in patients using each of the 3 image-processing algorithms. The region-of-interest approach showed multiple regions with lower FA in patients with schizophrenia, with overlap at all 4 sites in the corpus callosum and posterior thalamic radiation. The tract-based spatial statistic approach showed (1) global differences in 3 of the 4 cohorts and (2) lower frontal FA at the Iowa site. Finally, the pothole approach showed a significantly greater number of WM potholes in patients compared to controls at each of the 4 sites. In conclusion, the spatial characteristics of WM abnormalities in schizophrenia reflect a combination of a global low-level decrease in FA, suggesting a diffuse process, coupled with widely dispersed focal reductions in FA that vary spatially among individuals (ie, potholes).Key words: diffusion tensor imaging, fractional anisotropy, pothole, tract-based spatial statistics 相似文献
50.
Sarah M. Wilson Amie R. Newins Alyssa M. Medenblik Nathan A. Kimbrel Eric A. Dedert Terrell A. Hicks Lydia C. Neal Jean C. Beckham Patrick S. Calhoun 《Women's health issues》2018,28(6):514-523