全文获取类型
收费全文 | 18935篇 |
免费 | 1786篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 143篇 |
儿科学 | 558篇 |
妇产科学 | 328篇 |
基础医学 | 2803篇 |
口腔科学 | 432篇 |
临床医学 | 2251篇 |
内科学 | 3950篇 |
皮肤病学 | 474篇 |
神经病学 | 1461篇 |
特种医学 | 710篇 |
外科学 | 3115篇 |
综合类 | 430篇 |
一般理论 | 10篇 |
预防医学 | 1613篇 |
眼科学 | 264篇 |
药学 | 1253篇 |
1篇 | |
中国医学 | 10篇 |
肿瘤学 | 967篇 |
出版年
2021年 | 225篇 |
2020年 | 176篇 |
2019年 | 265篇 |
2018年 | 257篇 |
2017年 | 239篇 |
2016年 | 262篇 |
2015年 | 294篇 |
2014年 | 400篇 |
2013年 | 575篇 |
2012年 | 885篇 |
2011年 | 828篇 |
2010年 | 481篇 |
2009年 | 493篇 |
2008年 | 759篇 |
2007年 | 834篇 |
2006年 | 814篇 |
2005年 | 822篇 |
2004年 | 756篇 |
2003年 | 738篇 |
2002年 | 676篇 |
2001年 | 573篇 |
2000年 | 668篇 |
1999年 | 550篇 |
1998年 | 309篇 |
1997年 | 282篇 |
1996年 | 254篇 |
1995年 | 214篇 |
1994年 | 195篇 |
1993年 | 211篇 |
1992年 | 492篇 |
1991年 | 485篇 |
1990年 | 416篇 |
1989年 | 439篇 |
1988年 | 423篇 |
1987年 | 390篇 |
1986年 | 374篇 |
1985年 | 341篇 |
1984年 | 326篇 |
1983年 | 235篇 |
1982年 | 154篇 |
1981年 | 156篇 |
1980年 | 146篇 |
1979年 | 263篇 |
1978年 | 173篇 |
1977年 | 137篇 |
1976年 | 146篇 |
1975年 | 124篇 |
1974年 | 166篇 |
1973年 | 163篇 |
1972年 | 157篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Using data from the National Health and Nutrition Examination Survey (NHANES II) 1976-1980, we demonstrate how cross-sectional total serum cholesterol surveillance data can be used by an individual to assess current and future personal cholesterol risk status. We propose statistical models, based on a person's current measured cholesterol level and the relationship between cross-sectional age and cholesterol percentile estimates, that will allow prediction of future cholesterol levels or the age at which specified cholesterol risk levels will be reached if no cholesterol-altering intervention is taken. These models incorporate the observed variation in the NHANES II data and expected intraperson biological variation and intralaboratory analytical variation. We illustrate the adequacy of the models using data from the longitudinal Framingham Study. 相似文献
22.
23.
K Kuwaki C Knosalla F J M F Dor B Gollackner Y-L Tseng S Houser D K C Cooper 《The Journal of heart and lung transplantation》2005,24(1):92-94
Troponin T levels have been monitored in baboons (n = 8) undergoing pig heterotopic heart transplantation, and correlated with a decrease in graft contractions and graft survival. Pig heart graft survival was from 12 to 139 days (mean 45, median 33), and graft failure was associated with predominant thrombotic microangiopathy and ischemia, with focal hemorrhage, and edema. An increase in troponin T levels 5 to 6 days before graft failure correlated closely with diminished graft contractions. An increase in troponin T was a reliable indicator that graft dysfunction was occurring. 相似文献
24.
Richard M. Cooper 《Journal canadien d'anesthésie》2007,54(1):54-57
PURPOSE: Two cases are presented wherein the GlideScope videolaryngoscope (GVL) facilitated laryngeal exposure and successful endotracheal intubation, but resulted in pharyngeal injury. CLINICAL FEATURES: GlideScope videolaryngoscopy was performed in two female patients, whose airways were anticipated to present difficulties for direct laryngoscopy. In the first case, following induction of anesthesia, moderate difficulty was encountered in directing the endotracheal tube (ETT) into the patient's larynx. In the second case, minimal difficulty with the GVL was experienced, and no problems were identified with airway instrumentation until the drapes covering the patient's face were removed. In both instances, the ETT had passed through the right palatopharyngeal arch, requiring suturing in the first patient, and electrocautery in the second patient. CONCLUSION: There have been no previously published reports of injuries related to GlideScope laryngoscopy, but perforation of the palatopharyngeal arch occurring in two patients demonstrates a rare but potentially important complication of the GVL. Strategies to minimize this complication are considered. 相似文献
25.
26.
Mary T Fox Angela Cooper Brathwaite Souraya Sidani 《Revue canadienne de recherche en sciences infirmières》2004,36(3):20-30
Repeated measures designs are often used to evaluate the effectiveness of interventions. In these designs, the outcomes are measured on several occasions before and after implementation of the intervention. Two statistical methods, the repeated measures analysis of variance (RM-ANOVA) and hierarchical linear models (HLM), can be used to analyze the data. The authors provide an overview of the statistical models underlying RM-ANOVA and HLM and discuss the strengths and limitations of each. They propose that the 2 methods are complementary in determining the effectiveness of interventions. 相似文献
27.
D De AJ Kanwar S Handa 《Journal of the European Academy of Dermatology and Venereology》2006,20(7):853-859
BACKGROUND: Diagnosis of atopic dermatitis (AD) depends on clinical features because no definitive diagnostic test exists. Criteria proposed by Hanifin and Rajka (Acta Derm Venereol (Stockh) 1980; Suppl 92: 44-47) were acceptable for hospital-based studies but were found not to be suitable for field studies. A UK working party formulated clinical diagnostic criteria that could be used in both hospital and epidemiological settings. Validation studies of the criteria showed widely variable results, probably due to different clinical settings and ethnicity. AIM AND OBJECTIVE: This study was undertaken to validate Hanifin and Rajka's criteria and to assess the comparative efficacy of their criteria and the UK working party's diagnostic criteria in the diagnosis of AD in a hospital setting in North India. SUBJECTS AND METHODS: This study serially included 101 patients with AD and 48 controls of paediatric age group. The study period was from July 2003 to December 2004. RESULTS: Hanifin and Rajka's criteria (sensitivity 96%, specificity 93.75%, positive predictive value 97% (PPV) and negative predictive value (NPV) 91.84%) had a statistical advantage over the UK working party's diagnostic criteria (sensitivity 86%, specificity 95.83%, PPV 97.75% and NPV 76.67%), with a P-value < 0.005. 相似文献
28.
N. M. van Schoor D. L. Knol C. A. W. Glas R. W. J. G. Ostelo A. Leplège C. Cooper O. Johnell P. Lips 《Osteoporosis international》2006,17(4):543-551
Introduction Vertebral deformities are a common consequence of osteoporosis and are known to decrease quality of life. The Qualeffo–41
is a quality-of-life questionnaire especially developed for measuring quality of life in patients with vertebral deformities.
It consists of 41 questions arranged in five domains: pain, physical function, social function, general health perception,
and mental function. The objectives of this study were: (1) to develop a shorter version of the Qualeffo–41 by removing redundant
questions; and (2) to investigate the scale characteristics, reliability, and validity of this shorter version.
Methods The study was performed using data from the Qualeffo validation study and the Multiple Outcomes of Raloxifene Evaluation (MORE)
study. The analyses were performed in patients with vertebral deformities (n=579). Factor analysis on polychoric correlations and an item response theory (IRT) model, i.e., the generalized partial credit
model (GPCM), were used to create a shorter version of Qualeffo–41. Using GPCM, scoring weights were computed for all items.
Results Three items were removed from the data set because of too many missing values. Factor analysis identified three instead of
five domains: (1) pain, (2) physical function, and (3) mental function. Five items had factor loadings <0.4 and were not included
in the GPCM. After excluding several items, the domains pain (four items), physical function (18 items), and mental function
(nine items) showed a good, reasonable, and excellent fit, respectively. This indicates that the mental function domain and
the pain domain are more unidimensional than the physical function domain. All three domains showed a very high correlation
(r ≥0.95) with the corresponding domains of the Qualeffo–41.
Conclusions Qualeffo–31 was developed, consisting of three domains with a reasonable to excellent fit to the GPCM. Although the fit to
the GPCM supports the construct validity of the Qualeffo–31, validation in a new study should be performed before using it
in practice. 相似文献
29.
R A Cooper 《Journal of rehabilitation research and development》1992,29(3):29-34
The purpose of this study was to determine the relationship between selected anthropometric and physiological variables and 10K time. Eleven male wheelchair athletes with spinal cord injuries in training for national competition performed continuous progressive exercise tests on a wheelchair ergometer to determine maximal metabolic and cardiorespiratory values. Anthropometric data were also collected. The laboratory data were analyzed for correlation with the best 10K time of each subject during the test period. The subjects averaged 27 min 30 sec for their 10K races, 2.49 L.min-1 for VO2max and 35 percent for maximal gross mechanical efficiency during submaximal exercise. Speed at peak oxygen consumption (r = -0.66), gross mechanical efficiency (r = -0.56), and body density (r = -0.57) was found to be significantly (p less than 0.10) correlated with 10K time. The results show very little correlation between VO2max and 10K time (r = 0.02). Further study is indicated for the relationship between gross mechanical efficiency, speed at maximal oxygen consumption, body density, and 10K time; these variables may be useful in evaluating training programs for improving race performance. 相似文献
30.
Use of a new videolaryngoscope (GlideScope®) in the management of a difficult airway 总被引:13,自引:0,他引:13
Richard M. Cooper 《Journal canadien d'anesthésie》2003,50(6):611-613
PURPOSE: To describe the clinical use of a new videolaryngoscope in a patient who had repeatedly been difficult or impossible to intubate by conventional direct laryngoscopy. This device provided excellent glottic visualization and permitted easy endotracheal intubation. CLINICAL FEATURES: A 74-yr-old male presenting for repeat elective surgery had a history of failed intubations by direct laryngoscopy and pulmonary aspiration with a laryngeal mask airway. He refused awake flexible fibreoptic intubation. After the induction of general anesthesia, laryngoscopy was performed using a GlideScope. This provided complete glottic exposure and easy endotracheal intubation. CONCLUSION: This new videolaryngoscope provided excellent laryngeal exposure in a patient whom multiple experienced anesthesiologists had repeatedly found to be difficult or impossible to intubate using direct laryngoscopy. The clinical role of this device awaits confirmation in a large series of difficult airways. 相似文献