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   920篇
  免费   53篇
  国内免费   3篇
耳鼻咽喉   5篇
儿科学   26篇
妇产科学   42篇
基础医学   82篇
口腔科学   22篇
临床医学   84篇
内科学   197篇
皮肤病学   22篇
神经病学   53篇
特种医学   67篇
外科学   239篇
综合类   6篇
预防医学   60篇
眼科学   4篇
药学   23篇
肿瘤学   44篇
  2023年   2篇
  2022年   3篇
  2021年   17篇
  2020年   13篇
  2019年   24篇
  2018年   17篇
  2017年   16篇
  2016年   17篇
  2015年   22篇
  2014年   24篇
  2013年   32篇
  2012年   50篇
  2011年   66篇
  2010年   40篇
  2009年   33篇
  2008年   67篇
  2007年   57篇
  2006年   48篇
  2005年   51篇
  2004年   35篇
  2003年   32篇
  2002年   39篇
  2001年   14篇
  2000年   24篇
  1999年   24篇
  1998年   15篇
  1997年   11篇
  1996年   6篇
  1995年   5篇
  1994年   7篇
  1993年   4篇
  1992年   13篇
  1991年   11篇
  1990年   11篇
  1989年   10篇
  1988年   14篇
  1987年   14篇
  1986年   15篇
  1985年   9篇
  1984年   7篇
  1983年   4篇
  1982年   5篇
  1981年   3篇
  1980年   4篇
  1979年   10篇
  1978年   8篇
  1977年   2篇
  1976年   5篇
  1975年   2篇
  1970年   3篇
排序方式: 共有976条查询结果,搜索用时 0 毫秒
91.
Genetic mediated physiological processes that rely on both pharmacological and nutritional principles hold great promise for the successful therapeutic targeting of reduced carbohydrate craving, body-friendly fat loss, healthy body recomposition, and overall wellness. By integrating an assembly of scientific knowledge on inheritable characteristics and environmental mediators of gene expression, we review the relationship of genes, hormones, neurotransmitters, and nutrients as they correct unwanted weight gain coupled with unhappiness. In contrast to a simple one-locus, one-mechanism focus on pharmaceuticals alone, we hypothesize that the use of nutrigenomic treatment targeting multi-physiological neurological, immunological, and metabolic pathways will enable clinicians to intercede in the process of lipogenesis by promoting lipolysis while attenuating aberrant glucose cravings. In turn, this approach will enhance wellness in a safe and predictable manner through the use of a Genetic Positioning System (GPS) Map. The GPS Map, while presently incomplete, ultimately will serve not only as a blueprint for personalized medicine in the treatment of obesity, but also for the development of strategies for reducing many harmful addictive behaviors and promoting optimal health by using substances compatible with the body’s immune system.  相似文献   
92.
In pentobarbital-anesthetized cats, over arterial paCO2 values of 20–60 mm Hg, cerebral blood flow (CBF, Xenon) and cardiac output (CO, thermal dilution) show positively inflected curves with slopes significantly greater than zero. To examine the role of the locus coeruleus (LC) in these responses, bilateral stereotactic thermo-coagulation lesions of the LC were made. The effect of lesions confirmed to involve the LC bilaterally (n= 10), were compared with the effects of misdirected lesions placed in the cerebellum abd lateral to the LC (n= 10) and sham lesions (n= 10). Ted days after the lesioning procedure, the animals were re-anesthetized with pentobarbital and paCO2 response curves were determined for CBF and CO prior to and following intravenous administration of propranolol (1 mg/kg, i.v.). The results obtained with the sham-operated animals and the animals with lesions outside of the LC were indistinguishable. Bilateral LC lesions had no significant effect on normocapnic CBF as compared to control animals. They did, however, significantly reduce the slope of the CBF paCO2 response curve. Propranolol produced a significant reduction in CBF in lesioned and non-lesioned animals measured at all levels of pCO2 and did not alter the slope of the pCO2 response curve for any group as compared to predrug values. Bilateral lesions of the LC did not significantly alter either normacapnic CO or the slope of the CO-paCO2 relationship, but did reduce the elevation in mean arterial blood pressure otherwise observed during hypercarbia. Measurement of norepinephrine levels in cortex indicate a close indicate a correlation between the ability of the lesion to reduce norepinephrine content and produce the observed physiological effects. The results of these experiments suggest that the hypercapnic response of CBF, but not CO to arterial paCO2 is modulated by systems which traverse the dorsal brainstem. The role of the locus coeruleus-catecholamine cell bodies in this effect, however, must be considered speculative until further transmitter-selective interventions are carried out.  相似文献   
93.
Effect of L-carnitine supplementation on plasma ketone body (KB) and triglyceride (TG) concentrations was studied in ten premature infants requiring combined enteral and parenteral nutrition. At the second week of life (9 to 14 days of age) the infants were randomly divided into two groups. Five of them (plasma carnitine value, 33.77 +/- 2.48 mumol/l; mean +/- SEM) received oral L-carnitine supplementation (60 mumol/kg daily) added to pasteurized pooled human milk for seven consecutive days; additional five (plasma carnitine value, 36.70 +/- 5.19 mumol/l) served as controls. Composition of the daily diet was nearly constant in the study period. On the seventh day, prior to an Intralipid infusion, plasma carnitine and ketone body levels were significantly increased in the supplemented group as compared to controls or to previous values of the same group. In response to lipid infusion the fat load induced ketone body production was significantly higher in the supplemented group as compared to controls, whereas the triglycerides reached higher levels in the control group. It is suggested that L-carnitine supplementation in low-weight newborns promotes ketone body formation from endogenous stores as well as from exogenous fat supply, and thus may enhance triglyceride utilization.  相似文献   
94.
Healthcare workers (HCWs) are considered to run a higher occupational risk of becoming infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and develop coronavirus disease (COVID-19) than the rest of the population. The aim of this study was to describe and analyse the characteristics of work-related COVID-19 in Croatian HCWs. Study participants were HCWs who contacted their occupational physician between 1 May 2020 and 12 November 2020 with a request for the registration of COVID-19 as an occupational disease. All participants filled out our online Occupational COVID-19 in Healthcare Workers Questionnaire. The study included 59 HCWs (median age 45.0, interquartile range 36.0–56.0 years). Most (78 %) were nurses or laboratory technicians, and almost all (94.9 %) worked in hospitals. Hierarchical cluster analysis revealed three clusters of COVID-19-related symptoms: 1) elevated body temperature with general weakness and fatigue, 2) diarrhoea, and 3) headache, muscle and joint pain, anosmia, ageusia, and respiratory symptoms (nasal symptoms, burning throat, cough, dyspnoea, tachypnoea). Almost half (44.6 %) reported comorbidities. Only those with chronic pulmonary conditions were more often hospitalised than those without respiratory disorders (57.1 % vs. 2.5 %, respectively; P=0.001). Our findings suggest that work-related COVID-19 among Croatian HCWs is most common in hospital nurses/laboratory technicians and takes a mild form, with symptoms clustering around three clinical phenotypes: general symptoms of acute infection, specific symptoms including neurological (anosmia, ageusia) and respiratory symptoms, and diarrhoea as a separate symptom. They also support evidence from other studies that persons with chronic pulmonary conditions are at higher risk for developing severe forms of COVID-19.Key words: comorbidity, hospitalisation, questionnaire, SARS-CoV-2, symptom clustering  相似文献   
95.
The improvement of MRI speed with parallel acquisition is ultimately an SNR-limited process. To offset acquisition- and reconstruction-related SNR losses, practical parallel imaging at high accelerations should include the use of a many-element array with a high intrinsic signal-to-noise ratio (SNR) and spatial-encoding capability, and an advantageous imaging paradigm. We present a 32-element receive-coil array and a volumetric paradigm that address the SNR challenge at high accelerations by maximally exploiting multidimensional acceleration in conjunction with noise averaging. Geometric details beyond an initial design concept for the array were determined with the guidance of simulations. Imaging with the support of 32-channel data acquisition systems produced in vivo results with up to 16-fold acceleration, including images from rapid abdominal and MRA studies.  相似文献   
96.
97.

BACKGROUND

Significant proportions of young people experience body dissatisfaction, which has implications for psychological and physical well‐being. Lesson content and perceived competence may be important variables for the experience of body dissatisfaction, yet these have been underexplored in physical education. The aim of this cross‐sectional study is to identify the relationships between body dissatisfaction and perceptions of competence, and to explore whether body dissatisfaction depends on lesson content.

METHODS

A paper‐and‐pencil questionnaire was completed by 446 (210 boys, 236 girls) 13‐ to 14‐year‐old pupils from 37 physical education classes. The questionnaire assessed body dissatisfaction and perceived competence in physical education. Lesson content was also recorded. Twenty‐nine of the classes were engaged in team activities, eg, ball games. Eight classes were engaged in individual activities, eg, fitness.

RESULTS

Multilevel analysis identified a significant negative association between body dissatisfaction and perceptions of competence in physical education. Lesson content did not significantly predict variations in body dissatisfaction scores.

CONCLUSIONS

Teachers should focus on enhancing pupils' perceptions of competence in physical education to support the development of body satisfaction.
  相似文献   
98.

Objectives

To implement, examine, and compare three multichannel transmit/receive coil configurations for cardiovascular MR (CMR) at 7T.

Methods

Three radiofrequency transmit-receive (TX/RX) coils with 4-, 8-, and 16-coil elements were used. Ten healthy volunteers (seven males, age 28?±?4?years) underwent CMR at 7T. For all three RX/TX coils, 2D CINE FLASH images of the heart were acquired. Cardiac chamber quantification, signal-to-noise ratio (SNR) analysis, parallel imaging performance assessment, and image quality scoring were performed.

Results

Mean total examination time was 29?±?5?min. All images obtained with the 8- and 16-channel coils were diagnostic. No significant difference in ejection fraction (EF) (P?>?0.09) or left ventricular mass (LVM) (P?>?0.31) was observed between the coils. The 8- and 16-channel arrays yielded a higher mean SNR in the septum versus the 4-channel coil. The lowest geometry factors were found for the 16-channel coil (mean ± SD 2.3?±?0.5 for R?=?4). Image quality was rated significantly higher (P?Conclusions All three coil configurations are suitable for CMR at 7.0T under routine circumstances. A larger number of coil elements enhances image quality and parallel imaging performance but does not impact the accuracy of cardiac chamber quantification.

Key Points

? Cardiac chamber quantification using 7.0T magnetic resonance imaging is feasible. ? Examination times for cardiac chamber quantification at 7.0T match current clinical practice. ? Multichannel transceiver RF technology facilitates improved image quality and parallel imaging performance. ? Increasing the number of RF channels does not influence cardiac chamber quantification.  相似文献   
99.
100.
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