全文获取类型
收费全文 | 63259篇 |
免费 | 4392篇 |
国内免费 | 112篇 |
专业分类
耳鼻咽喉 | 583篇 |
儿科学 | 2427篇 |
妇产科学 | 1668篇 |
基础医学 | 8095篇 |
口腔科学 | 736篇 |
临床医学 | 9427篇 |
内科学 | 11133篇 |
皮肤病学 | 813篇 |
神经病学 | 6265篇 |
特种医学 | 1341篇 |
外科学 | 5555篇 |
综合类 | 762篇 |
一般理论 | 111篇 |
预防医学 | 8560篇 |
眼科学 | 1019篇 |
药学 | 4123篇 |
中国医学 | 67篇 |
肿瘤学 | 5078篇 |
出版年
2023年 | 289篇 |
2022年 | 470篇 |
2021年 | 1134篇 |
2020年 | 770篇 |
2019年 | 1180篇 |
2018年 | 1328篇 |
2017年 | 1082篇 |
2016年 | 1156篇 |
2015年 | 1351篇 |
2014年 | 1885篇 |
2013年 | 2995篇 |
2012年 | 4347篇 |
2011年 | 4612篇 |
2010年 | 2561篇 |
2009年 | 2320篇 |
2008年 | 4171篇 |
2007年 | 4406篇 |
2006年 | 4264篇 |
2005年 | 4369篇 |
2004年 | 4175篇 |
2003年 | 3887篇 |
2002年 | 3650篇 |
2001年 | 718篇 |
2000年 | 547篇 |
1999年 | 667篇 |
1998年 | 774篇 |
1997年 | 688篇 |
1996年 | 573篇 |
1995年 | 560篇 |
1994年 | 497篇 |
1993年 | 400篇 |
1992年 | 455篇 |
1991年 | 389篇 |
1990年 | 363篇 |
1989年 | 388篇 |
1988年 | 360篇 |
1987年 | 327篇 |
1986年 | 308篇 |
1985年 | 325篇 |
1984年 | 318篇 |
1983年 | 289篇 |
1982年 | 287篇 |
1981年 | 267篇 |
1980年 | 220篇 |
1979年 | 200篇 |
1978年 | 198篇 |
1977年 | 132篇 |
1975年 | 115篇 |
1974年 | 152篇 |
1973年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
61.
62.
63.
BACKGROUND: Patients with multi-handicaps present clinical challenges and are underserved. Central nervous system dysfunction and ocular disorders with this population are prevalent and well-documented. However, vision care outcomes data are limited and specific visual function recommendations to caregivers are rarely cited. METHODS: The charts of 110 multiply handicapped adults residing in 22 group homes in Wayne County. Michigan were retrospectively studied to identify ocular profiles and predictors of visual function. RESULTS: Sixty-five percent of the subjects were male and 80% were ages 26 to 55 years. There was no expressive language in 41%, and 37% were non-ambulatory. The median visual impairment level was moderate in both eyes (based on WHO). Significant associations between visual impairment level and subpopulations (such as seizure disorder, mental retardation without specific etiology, cerebral palsy, and Down syndrome) were identified. Successful spectacle wear statistically increased with higher refractive errors. Associations between cataract, nystagmus, and strabismus with particular subpopulations were significant (all P values < 0.0182). CONCLUSIONS: Clinicians who evaluate patients with multi-handicaps have few known predictors of treatment success. This study indicates that useful predictors of visual function can be made from refractive error, systemic conditions, and ocular diagnoses. No significant relationship was found with cognitive level and either vision impairment or spectacle use. The authors attribute successful implementation of recommendations to communication with group home caregivers. 相似文献
64.
D J Brooks J S Gibbs P Sharp S Herold D R Turton S K Luthra E M Kohner S R Bloom T Jones 《Journal of cerebral blood flow and metabolism》1986,6(2):240-244
Regional cerebral [11C]3-O-methyl-D-glucose ([11C]MeG) uptake kinetics have been measured in five insulin-dependent diabetic patients and four normal controls using positron emission tomography (PET). Concomitant measurement of regional cerebral blood volume and CBF enabled corrections for the presence of intravascular [11C]MeG signal in cerebral regions of interest to be carried out, and regional cerebral [11C]MeG unidirectional extraction fractions to be computed. Four of the five diabetic subjects were studied with their fasting plasma glucose level clamped at a normoglycaemic level (4 mM), and four were studied at hyperglycaemic plasma glucose levels (mean 13 mM). The four diabetic subjects whose fasting plasma glucose levels were clamped at a normoglycaemic level of 4 mM had mean fasting whole-brain, cortical, and white matter [11C]MeG extraction fractions of 15, 15, and 16%, respectively, values similar to those found for the four normal controls (whole brain, 14%; cortex, 13%; white matter, 17%). Mean regional cerebral [11C]MeG extraction fractions were significantly reduced in diabetic subjects during hyperglycaemia whether their plasma insulin levels were undetectable or whether they were raised by continuous intravenous insulin infusion. Such a reduction in [11C]MeG extraction under hyperglycaemic conditions can be explained entirely in terms of increased competition between [11C]MeG and D-glucose for the passive facilitated transport carrier system for hexoses across the blood-brain barrier (BBB). It is concluded that the number and affinity of D-glucose carriers present in the BBB are within normal limits in treated insulin-dependent diabetic subjects. In addition, insulin appears to have no effect on the transport of D-glucose across the BBB. 相似文献
65.
PURPOSE: Two experiments explored the extent to which induced blur, reduced luminance, and reduced visual fields affect drivers' steering performance in a driving simulator. METHODS: In experiment 1, ten young participants (M = 21.2 years) drove at approximately 89 km/h (55 mph) along a curvy roadway while being exposed to blur (0 to + 10 D), luminance (0.003 to 16.7 cd/m), and visual field (1.7 and 150 degrees) manipulations. In experiment 2, a new group of ten young participants (M = 18.5 years) drove while exposed to seven visual field sizes (1.7 to 150 degrees). RESULTS: Steering was sensitive to a reduced field size but not to the blur and luminance challenges. Acuity, on the other hand, was sensitive to the blur and luminance challenges but not to reduced field size. DISCUSSION: In healthy young drivers, steering performance is remarkably robust to severe blur and to extremely low luminances. These results support a key element of the selective degradation hypothesis advanced by Leibowitz and colleagues--that steering abilities are preserved at night even when the ability to recognize objects and hazards is not. Additional research should address the other element of this hypothesis--that drivers fail to appreciate the extent to which their visual abilities are degraded at night. 相似文献
66.
67.
John Nietupski Terry McQuillen Deana Duncan Berg Judy Weyant Vicki Daugherty Stephanie Bildstein Amber O'Connor Judy Warth Susan M. Hamre-Nietupski 《Journal of developmental and physical disabilities》2004,16(2):179-192
This paper describes an innovative approach to preparing high school students with mild disabilities for challenging careers in high tech industries, called High School High Tech (HSHT). Iowa's HSHT Goes to College program has three central elements, each of which is discussed in this paper: High School Preparation—assisting students in identifying a suitable high tech career goal; Higher Education Preparation and Supports—assisting students in selecting college/training programs that match their career goal, and in successfully completing their postsecondary programs; Workforce Entry Assistance—linking students with employers and launching their high tech careers. The paper concludes with a presentation of outcomes to date and recommendations for program enhancements. The information presented here is intended to assist education and rehabilitation professionals interested in establishing similar efforts across the nation. 相似文献
68.
Lesley B Milgrom Jo Ann Brooks Rong Qi Karen Bunnell Susie Wuestfeld Daniel Beckman 《American journal of critical care》2004,13(2):116-125
BACKGROUND: Acute pain is common after cardiac surgery and can keep patients from participating in activities that prevent postoperative complications. Accurate assessment and understanding of pain are vital for providing satisfactory pain control and optimizing recovery. OBJECTIVES: To describe pain levels for 5 activities expected of patients after cardiac surgery on postoperative days 1 to 6 and changes in pain levels after chest tube removal and extubation. METHODS: Adults who underwent cardiac surgery were asked to rate the pain associated with various types of activities on postoperative days 1 to 6. Pain levels were compared by postoperative day, activity, and type of cardiac surgery. Pain scores before and after chest tube removal and extubation also were analyzed. RESULTS: Pain scores were higher on earlier postoperative days. The order of overall pain scores among activities (P < .01) from highest to lowest was coughing, moving or turning in bed, getting up, deep breathing or using the incentive spirometer, and resting. Changes in pain reported with coughing (P = .03) and deep breathing or using the incentive spirometer (P = .005) differed significantly over time between surgery groups. After chest tubes were discontinued, patients had lower pain levels at rest (P = .01), with coughing (P = .05), and when getting up (P = .03). CONCLUSIONS: Pain relief is an important outcome of care. A comprehensive, individualized assessment of pain that incorporates activity levels is necessary to promote satisfactory management of pain. 相似文献
69.
70.