首页 | 官方网站   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   1224篇
  免费   100篇
  国内免费   7篇
医药卫生   1331篇
  2024年   2篇
  2023年   28篇
  2022年   77篇
  2021年   107篇
  2020年   58篇
  2019年   90篇
  2018年   71篇
  2017年   63篇
  2016年   70篇
  2015年   50篇
  2014年   73篇
  2013年   88篇
  2012年   102篇
  2011年   93篇
  2010年   42篇
  2009年   30篇
  2008年   62篇
  2007年   60篇
  2006年   47篇
  2005年   34篇
  2004年   26篇
  2003年   15篇
  2002年   19篇
  2001年   4篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1980年   3篇
  1979年   1篇
排序方式: 共有1331条查询结果,搜索用时 0 毫秒
1.
Poor maternal vitamin D status affects fetal and infant skeletal growth. The aim of the present study was to determine the association between newborn outcomes and maternal calcium and vitamin D intakes. Four hundred and forty-nine pregnant women, healthy at the point of delivery, and their newborns were enrolled in the study, which was performed in three university hospitals in Tehran in March 2004. Maternal anthropometric data and energy, protein, calcium and vitamin D intakes were collected, and newborn outcomes (weight, length, head circumference and 1-min Apgar score) were determined. Almost two-thirds of the mothers (64.3%) took no supplements during pregnancy. Only one-third of the mothers (33.8%) had adequate intakes of calcium and vitamin D (from supplements and foods) compared with the Recommended Dietary Allowances. Mean length at birth and 1-min Apgar score were higher in newborns whose mothers had adequate calcium and vitamin D intake than in newborns whose mothers had inadequate intake (p = 0.03 and p = 0.04, respectively). Significant correlations were found between adequate maternal calcium and vitamin D intake and both appropriate birth weight and 1-min Apgar score of newborns and weight gain of mothers during pregnancy. Informing mothers of the critical importance of consuming adequate amounts of calcium and vitamin D seems necessary.  相似文献   
2.
Abstract –  The aims of this study were to investigate the incidence of coronal fracture of the anterior teeth in North Jordanian schoolchildren and to study the main predisposing factors and the factors that may affect the severity of this fracture. A study group (958) comprising schoolchildren aged 13–15 years was chosen by a simple random method from five geographical areas in Irbid Governate, Jordan. All children completed a questionnaire related to history of trauma to their anterior teeth before they had a clinical examination for lip competence, lip line and amount of fracture. Overjet was recorded from a study cast made for each student. Statistical analysis was performed using chi-square test. The results showed a prevalence of 11% of coronal fracture with female-male ratio of 1:1. An increase in the overjet more than 3 mm doubled the incidence of coronal fracture while overjet more than 6 mm increased the incidence fourfold. There was higher incidence of coronal fracture associated with lip incompetence and low lip line ( P  < 0.01). The severity of fracture increased in children with a larger overjet ( P  < 0.001). It was concluded that overjet, lip competence and lip line were important predisposing factors to coronal fracture of the anterior teeth while the severity of the fracture was mainly determined by overjet.  相似文献   
3.
Current Internet-based teleconferencing techniques allow a referring pathologist to transmit real-time images from a microscope to a consultant, while maintaining a verbal conversation using Internet telephony. In our study, 50 randomly selected transbronchial biopsies from lung allograft recipients and 58 randomly selected endomyocardial biopsies from heart transplant patients were diagnosed by consultant pathologists using Internet-based teleconferencing methods. The referring pathologists acquired the real-time video images from the biopsies using a light microscope equipped with a phototube adapter and a video camera. The consultant pathologists viewed the processed images on a video monitor at 800 x 600 resolution, using a standard microcomputer equipped with Netmeeting software, and directed the referring pathologist to move the slide under the microscopy and/or change image magnification. The validity of telepathology diagnoses was assessed with kappa coefficients. Consultations were completed in 5 to 15 minutes per case. Sound transmission was unreliable, and in approximately 25% of consultations the referring pathologist needed to "call back" to reestablish verbal communication. In all but 2 transbronchial biopsies there was agreement between the original diagnosis and the diagnosis by telepathology (kappa = 0.92). In 48 of 58 endomyocardial biopsies there was concordance between the 2 diagnoses (kappa = 0.692). Only 3 out of 10 of these discrepancies were clinically significant (kappa = 0.897). Internet-based teleconferencing techniques provide effective and relatively inexpensive tools for real time telepathology consultations. The technology is probably best suited for the study of small specimens from patients that require rapid diagnosis by a consultant.  相似文献   
4.
结肠癌(CRC)是全世界至今未攻克的消化系统常见的恶性肿瘤之一。目前治疗CRC的临床手段均具有一定局限性,疗效不尽人意,从而导致治疗中途被迫停止或疗效欠佳。因此,寻找和研发具有治疗潜力、针对性强、不良反应小、经济性的新型候选药物迫在眉睫。中医药在改善上述症状方面具有西医不可替代的优势,并且中医药学历史悠久,君臣佐使、辨证用药具有调节人体状态的实践基础。近年来中医药在CRC的临床治疗领域有着显著的成效,尤其已有临床应用实践基础的中药复方及单体为干预治疗CRC提供了新的治疗方案,疗效确切、优势突出。具体体现在提高生活质量、改善临床症状,减轻化疗不良反应、延长生存期等方面。因此该文从CRC的现状、中医辨证论治基础上以“结肠癌”“中医药”“复方”及“单体”等为关键词,检索查阅近些年中英文相关文献。主要从“益气健脾”“清热解毒”“滋补肝肾”“补气养血”4个方面较为系统地介绍了中药复方及单体在治疗CRC领域的新进展。但因中药多组分、多靶点、多途径的特点,在今后仍然需要不断地深入探索中药复方及单体在治疗CRC领域的应用,以期使患者病痛和不良反应最小化、治疗效果最大化。为CRC治疗提供更宽广的前景和思路,为基于物质基础深入研究药效作用与机制提供参考。  相似文献   
5.
BackgroundThe aim of this study was to estimate the prevalence and to determine the associated factors of undiagnosed depression amongst hypertensive patients (HTNP) at primary health care centers (PHCC) in Gaza.MethodsA cross-sectional survey was conducted including 538 HTNP as a recruitment phase of a clustered randomized controlled trial. Data were collected through face-to-face structured interview, and depression status was assessed by Beck''s Depression Inventory (BDI-II). Data were analyzed by STATA version 14 using standard complex survey analyses, accounted for unresponsiveness and clustering approach. Generalized linear regression analysis was performed to assess associations.ResultsThe prevalence of undiagnosed clinical depression was 11.6% (95% confidence interval [CI]: 8.1, 16.3). Moreover, prevalence of 15.4% (95% CI: 10.8, 21.6) was found for mild depression symptoms. We found that non-adherence to antihypertensive medications (AHTNM) (β = 0.9, 95% CI: 0.17, 1.7), having more health-care system support (β = 2.8, 95% CI: 1.6, 3.9) and number of AHTNM (β = 1.5, 95% CI: 0.6, 2.5) remain significantly positively associated with BDI-II score. On the other hand, older age (β = -0.1, 95% CI: -0.2, -0.02), having better social support (β = -6.8, 95% CI: -8.9, -4.7) and having stronger patient-doctor relationship (β = -4.1, 95% CI: -6.9, -1.2) kept significantly negative association.ConclusionThe prevalence of undiagnosed depression was about one-quarter of all cases; half of them were moderate to severe. Routine screening of depression status should be a part of the care of HTNP in PHCC.  相似文献   
6.
To date, little is known about the duration and effectiveness of immunity as well as possible adverse late effects after an infection with SARS-CoV-2. Thus it is unclear, when and if liver transplantation can be safely offered to patients who suffered from COVID-19. Here, we report on a successful liver transplantation shortly after convalescence from COVID-19 with subsequent partial seroreversion as well as recurrence and prolonged shedding of viral RNA.  相似文献   
7.
Airflow limitation in patients with obstructive sleep apnea (OSA) leads to arousal, increased sympathetic nervous system activity, and elevated blood pressure, which causes a decrease in pulse transit time (PTT). The present study aims to evaluate the effect of CPAP therapy on PTT in patients with moderate to severe OSA. This was a cross‐sectional study. Split‐night polysomnography (PSG) study was performed for each participant with apnea‐hypopnea index (AHI) ≥ 15 before and during CPAP therapy. The PTT was calculated as the time interval between the R wave of the electrocardiogram and the following arrival point in fingertip photoplethysmography. PTT drop was defined as a fall in the PTT curve of ≥15 ms lasting at least for 3 s and at most for 30 s. PTT drop index was defined as the number of drops in PTT that occur per hour of sleep. A total of 30 patients were included. PTT significantly increased, and PTT drop index significantly decreased during CPAP therapy (P < 0.001). PTT was significantly correlated to sleep efficiency (r s = −0.376, P = 0.049) and oxygen desaturation index (ODI) (r s = −0.428, P = 0.018). PTT drop index was strongly correlated to AHI (r s = 0.802, P < 0.001), respiratory disturbance index (RDI) (r s = 0.807, P < 0.001), ODI (r s = 0.693, P < 0.001), arousal index (r s = 0.807, P < 0.001), and periodic leg movement (PLM) index (r s = 0.400, P = 0.035). Overall, the findings from this study indicated that the PTT drop index is a non‐invasive and useful marker for evaluating the severity of OSA and the effectiveness of treatment in patients with moderate to severe OSA.  相似文献   
8.
9.
ObjectivesTo assess the linear and angular cranial base measurements (Bjork polygon) in different anteroposterior (AP) skeletal relationships using Bjork-Jarabak analysis.Materials and MethodsPretreatment lateral cephalograms of 288 (146 women, 142 men, mean ages 21.24 ± 2.72 years and 22.94 ± 3.28 years, respectively) adult patients were divided into Class I, II, and III skeletal relationships according to their ANB angle. Linear and angular measurements of Bjork polygon were measured and compared among different skeletal relationships. Analysis of variance was performed to detect the differences among groups. Independent-sample t-test was used to detect differences between men and women.ResultsThe Class II skeletal relationship has a significantly larger saddle angle than Class III does (P < .05), whereas Class III has a significantly larger gonial angle than Class II does (P < .05). The articular angle and sum of Bjork polygon angles were not significantly different among groups (P > .05). Anterior (N-S) and posterior (S-Ar) cranial base lengths were similar in the different AP skeletal relationships (P > .05). The ramal height and body of the mandible length were significantly larger in Class III compared with Class I and II (P < .05). Women had a significantly larger articular angle than men did (P < .05), although men had significantly larger linear measurements of Bjork polygon than women did (P < .05).ConclusionsThe Class III skeletal relationship has a smaller saddle angle and larger mandibular length and gonial angle. Men have a larger cranial base and mandibular linear measurements and a smaller articular angle compared with women.  相似文献   
10.
The purpose of the present article is to study the bending strength of glulam prepared by plane tree (Platanus Orientalis-L) wood layers adhered by UF resin with different formaldehyde to urea molar ratios containing the modified starch adhesive with different NaOCl concentrations. Artificial neural network (ANN) as a modern tool was used to predict this response, too. The multilayer perceptron (MLP) models were used to predict the modulus of rapture (MOR) and the statistics, including the determination coefficient (R2), root mean square error (RMSE), and mean absolute percentage error (MAPE) were used to validate the prediction. Combining the ANN and the genetic algorithm by using the multiple objective and nonlinear constraint functions, the optimum point was determined based on the experimental and estimated data, respectively. The characterization analysis, performed by FTIR and XRD, was used to describe the effect of the inputs on the output. The results indicated that the statistics obtained show excellent MOR predictions by the feed-forward neural network using Levenberg–Marquardt algorithms. The comparison of the optimal output of the actual values obtained by the genetic algorithm resulting from the multi-objective function and the optimal output of the values estimated by the nonlinear constraint function indicates a minimum difference between both functions.  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-23

京公网安备 11010802026262号