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   1453篇
  免费   128篇
  国内免费   19篇
耳鼻咽喉   11篇
儿科学   29篇
妇产科学   51篇
基础医学   163篇
口腔科学   41篇
临床医学   164篇
内科学   372篇
皮肤病学   25篇
神经病学   70篇
特种医学   119篇
外科学   156篇
综合类   35篇
一般理论   1篇
预防医学   172篇
眼科学   51篇
药学   85篇
中国医学   2篇
肿瘤学   53篇
  2022年   13篇
  2021年   14篇
  2020年   14篇
  2019年   19篇
  2018年   19篇
  2017年   16篇
  2016年   14篇
  2015年   21篇
  2014年   38篇
  2013年   55篇
  2012年   69篇
  2011年   52篇
  2010年   41篇
  2009年   52篇
  2008年   32篇
  2007年   81篇
  2006年   63篇
  2005年   56篇
  2004年   49篇
  2003年   47篇
  2002年   45篇
  2001年   28篇
  2000年   35篇
  1999年   29篇
  1998年   36篇
  1997年   27篇
  1996年   22篇
  1995年   26篇
  1994年   20篇
  1993年   19篇
  1992年   19篇
  1991年   24篇
  1990年   25篇
  1989年   33篇
  1988年   29篇
  1987年   33篇
  1986年   27篇
  1985年   34篇
  1984年   19篇
  1983年   13篇
  1981年   18篇
  1980年   18篇
  1979年   16篇
  1978年   14篇
  1977年   18篇
  1976年   13篇
  1975年   28篇
  1974年   15篇
  1973年   21篇
  1969年   17篇
排序方式: 共有1600条查询结果,搜索用时 15 毫秒
991.
BackgroundTwo recent literature-based meta-analyses revealed that restrictive filling pattern (RFP) was associated with a 4-fold increase in the risk of death in patients with heart failure (HF) and postacute myocardial infarction (AMI). This similar but unique analysis evaluated the link between RFP and morbidity.Methods and ResultsProspective echocardiographic studies of patients post-AMI and with HF that reported HF morbidity were identified. Events (post-AMI: development of HF; HF: HF readmission) were compared between patients with and without RFP in both patient groups. Review Manager version 4.2.7 software was used for the analysis. Twelve post-AMI studies (1286 patients, 271 events) and 5 HF studies (647 patients, 176 events) were identified. RFP was associated with HF readmission in the HF patients (OR 2.96 [2.02–4.33] and development of HF post-AMI (OR 10.10 [7.02–14.51]). The event rate in the RFP group was the same regardless of disease category (49% post-AMI, 42% HF); however, RFP was less prevalent in the post-AMI group (22% versus 39%).ConclusionsThis literature-based meta-analysis confirms that RFP is a powerful predictor of HF hospitalization in patients with HF and especially the development of HF post-AMI. This is an important prognostic sign and should be incorporated into routine clinical practice.  相似文献   
992.
Abstract

Portions of the cognitive social learning model proposed by Price1.2 as an explanation for the development and maintenance of Type A behavior were examined empirically. Specifically, the hypothesis that Type A behavior is fostered by various beliefs and fears and that these same beliefs and fears arise, in part, as the result of certain parental characteristics was investigated. A questionnaire assessing Type A behavior and the beliefs, fears, and parental characteristics proposed by Price was constructed and administered to a sample of males and females. The results indicated moderate associations between the variables examined for both males and females, with no significant gender differences in the pattern of relationships. The findings are congruent with relationships proposed by Price's model. Implications of the model are discussed in terms of additional research needed.  相似文献   
993.
994.
ObjectiveOur goal was to determine the association between random admission hyperglycemia and new diagnosis of diabetes after discharge in patients hospitalized with pneumonia.MethodsClinical data, including the Pneumonia Severity Index, were prospectively collected on all 2124 patients without diabetes admitted with pneumonia to 6 hospitals in Edmonton, Alberta, Canada. Admission glucose was classified as: normal (4.0-6.0 mmol/L, reference group) versus mild (6.1-7.7 mmol/L), moderate (7.8-11.0 mmol/L), and severe (11.1-20.0 mmol/L) stress hyperglycemia. New diagnosis of diabetes over 5 years was ascertained using well-validated criteria within linked administrative databases. Multivariable Cox models were used, and sensitivity, specificity, and likelihood ratios were calculated.ResultsMean age was 68 years; 1091 (51%) were male, and 1418 (67%) had stress hyperglycemia. Over 5 years, 194 (14%) with stress hyperglycemia were diagnosed with diabetes. Compared with the 45 of 706 (6%) incidences of diabetes in normal glycemia patients (4.0-6.0 mmol/L), a strong graded increase in risk of new diabetes existed with increasing hyperglycemia: mild (59 of 841 [7%]; adjusted hazard ratio [aHR] 1.09; 95% confidence interval [CI], 0.74-1.61) versus moderate (86 of 473 [18%]; aHR 2.99; 95% CI, 2.07-4.31) versus severe (49 of 104 [47%]; aHR 11.43; 95% CI, 7.50-17.42). Among moderate-to-severe hyperglycemia (≥7.8 mmol/L) patients, the sensitivity, specificity, and positive and negative likelihood ratios for new diabetes were 57%, 77%, 2.1, and 0.6, respectively, with a number-needed-to-evaluate of 5 to detect one new case of diabetes.ConclusionModerate-to-severe random hyperglycemia in pneumonia patients admitted to the hospital is strongly associated with new diagnosis of diabetes. Opportunistic evaluation for diabetes may be warranted in this group.  相似文献   
995.
996.
A conventional MDI‐BD‐PTMO polyurethane is modified using 2 wt% polyurethanes (U) having copolyoxetane soft blocks with hydrophobic 3F, CF3CH2OCH2— and hydrophilic MEn, CH3O(CH2CH2O)nCH2—, n = 3, 7) side chains. In contrast to neat 3F‐co‐MEn‐U, 2 wt% 3F‐co‐MEn‐U compositions have physically stable morphologies and wetting behavior. Surface composition (XPS) and amphiphilic or contraphilic wetting are controlled by the 3F‐co‐MEn polyoxetane soft block architecture and MEn side chain length. Importantly, θrec can be tuned for 2 wt% 3F‐co‐MEn‐U compositions independent of swelling, which is controlled by the bulk polyurethane. AFM imaging leads to a new morphological model whereby fluorous/PEG‐hard block nanoaggregates combine to form near surface features culminating in micron‐scale texturing.  相似文献   
997.
998.
Guided self-help (GSH) is a recommended first step in treatment for bulimia nervosa (BN) and binge eating disorder (BED) (NICE, 2004). It remains unclear what makes some individuals more likely to respond to this form of treatment than others. Forty-eight patients participated in this study using a GSH programme for binge eating. Profiles of treatment completers and non-completers are compared, and reasons for non-completion explored. Completion of treatment was associated with significant improvements in mood, general functioning and on measures of dietary restraint, frequency of objective binge eating (OBE), laxative misuse, self-induced vomiting (SIV) and driven exercise. Improvements were maintained at follow-up. Treatment non-completers reported significantly higher pre-treatment levels of depression and weight concern, and lower levels of general health and vitality. Reasons for discontinuing treatment were related to perceptions of the GSH programme; practicalities of the programme; and readiness to change. Whilst GSH can be effective for a sub-group of patients, factors such as pre-morbid level of depression, degree of weight concern, perceptions of the programme, and readiness to change may increase the likelihood of non-completion.  相似文献   
999.
Calculated sweat rates (measured by body mass changes) and voluntary fluid intakes were monitored in elite level water polo players and swimmers during normal exercise sessions to determine fluid requirements to maintain fluid balance, and the degree of fluid replacement of these athletes. Data were collected from training and competition sessions for male water polo players (n = 23) and training sessions only for swimmers (n = 20 females; n = 21 males). The calculated average sweat rate and fluid intake rate during training sessions for male water polo players was 287 ml/h and 142 ml/h, respectively, with a rate of 786 ml/h and 380 ml/h during matches. During training sessions for male swimmers, the calculated average sweat rate and fluid intake rate per kilometre was 138 ml/km and 155 ml/km, respectively; and for female swimmers, 107 ml/km and 95 ml/km. There was a wide individual variation in fluid intake and sweat loss of both water polo players and swimmers. Dehydration experienced by athletes in this study was less than typically reported for "land-based" athletes. Errors inherent in the technique used in this study are acknowledged and may be significant in the calculation of reported sweat losses and levels of fluid balance in aquatic athletes.  相似文献   
1000.

Background

In order to assess relationships between thyroid hormone status and findings on brain MRI, a subset of babies was recruited to a multi-centre randomised, placebo-controlled trial of levothyroxine (LT4) supplementation for babies born before 28 weeks’ gestation (known as the TIPIT study, for Thyroxine supplementation In Preterm InfanTs). These infants were imaged at term-equivalence.

Materials and methods

Forty-five TIPIT participants had brain MRI using diffusion tensor imaging (DTI) to estimate white matter development by apparent diffusion coefficient (ADC), fractional anisotropy (FA) and tractography metrics of number and length of streamlines. We made comparisons between babies with the lowest and highest plasma FT4 concentrations during the initial 4 weeks after birth.

Results

There were no differences in DTI metrics between babies who had received LT4 supplementation and those who had received a placebo. Among recipients of a placebo, babies in the lowest quartile of plasma-free thyroxine (FT4) concentrations had significantly higher apparent diffusion coefficient measurements in the posterior corpus callosum and streamlines that were shorter and less numerous in the right internal capsule. Among LT4-supplemented babies, those who had plasma FT4 concentrations in the highest quartile had significantly lower apparent diffusion coefficient values in the left occipital lobe, higher fractional anisotropy in the anterior corpus callosum and longer and more numerous streamlines in the anterior corpus callosum.

Conclusion

DTI variables were not associated with allocation of placebo or thyroid supplementation. Markers of poorly organised brain microstructure were associated with low plasma FT4 concentrations after birth. The findings suggest that plasma FT4 concentrations affect brain development in very immature infants and that the effect of LT4 supplementation for immature babies with low FT4 plasma concentrations warrants further study.  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