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   3329篇
  免费   334篇
  国内免费   86篇
耳鼻咽喉   21篇
儿科学   127篇
妇产科学   71篇
基础医学   426篇
口腔科学   63篇
临床医学   235篇
内科学   781篇
皮肤病学   22篇
神经病学   233篇
特种医学   103篇
外科学   526篇
综合类   321篇
预防医学   215篇
眼科学   20篇
药学   235篇
  1篇
中国医学   103篇
肿瘤学   246篇
  2024年   13篇
  2023年   93篇
  2022年   218篇
  2021年   191篇
  2020年   212篇
  2019年   167篇
  2018年   177篇
  2017年   124篇
  2016年   150篇
  2015年   129篇
  2014年   237篇
  2013年   193篇
  2012年   144篇
  2011年   152篇
  2010年   119篇
  2009年   110篇
  2008年   139篇
  2007年   118篇
  2006年   102篇
  2005年   90篇
  2004年   90篇
  2003年   56篇
  2002年   75篇
  2001年   66篇
  2000年   55篇
  1999年   49篇
  1998年   31篇
  1997年   23篇
  1996年   17篇
  1995年   12篇
  1994年   13篇
  1993年   15篇
  1992年   14篇
  1991年   13篇
  1990年   9篇
  1989年   10篇
  1988年   11篇
  1985年   15篇
  1984年   39篇
  1983年   22篇
  1982年   24篇
  1981年   37篇
  1980年   29篇
  1979年   23篇
  1978年   26篇
  1977年   11篇
  1976年   22篇
  1975年   15篇
  1974年   18篇
  1973年   14篇
排序方式: 共有3749条查询结果,搜索用时 12 毫秒
101.
目的探讨股骨大转子长斜形截骨在治疗成人高脱位发育性髋关节脱位(developmental dislocation of hip DDH)中的临床疗效。方法实验组:选取2012年2月至2015年2月本院收治的11例高脱位DDH患者的临床资料,11例患者均采用全髋人工关节假体置换联合股骨大转子长斜形截骨钢丝内固定术。其中,男3例,女8例。年龄45~72岁,平均56.5岁,术后末次随访體关节功能按改良Merle d'Aubingne-Postel评分系统评估。对照组:通过医院病历管理平台获得自2009年1月至2012年1月本院采用全髋人工关节假体置换联合股骨大转子下横形截骨术治疗17例患者的临床资料,最后电话得到随访的有12例,获取病历数据得知12例患者的平均手术时间、出血量等相关数据。将实验组与对照组的数据进行对比分析。结果实验组11例患者均得到随访,随访时间12~18个月,平均15.8个月。平均手术时间(120.05±32.50) min,术中出血量(270.15±72.50) mL,末次随访髋关节功能按改良Merle d'Aubingne-Postel评分系统来评估:优7例,良3例,可1例,差0例,优良率90.91%。无1例发生坐骨神经损伤。对照组平均手术时间(160.08±95.50) min,术中出血量(380.02±75.70) mL,优良率91.67%。有1例坐骨神经损伤,末次随访时已恢复。两组病例治疗效果的优良率通过χ~2检验,P0.05。手术时间及出血量通过t检验,p0.05。结论采用股骨大转子长斜形截骨能够获得与转子下横形截骨相同的临床效果,但其手术时间、术中出血量明显减少,术中手术创伤减小、手术操作难度降低。  相似文献   
102.
Investigations show significant disagreement among mental health professionals in diagnosing schizophrenia.1–11 Recently, computer-based systems have been used in attempts to improve diagnostic consistency. Spitzer and Endicott, among others, have devised a computer program using the Mental Status Examination Report (MSER) as input data.12–19 The MSER is a systematic, relatively objective inventory of observed behaviors used to obtain a mental status. The MSER was used at the Hillside Division during 1973 and 1974. It was filled out 1 week after admission by therapists who were specially trained for this task. It was noted that a nonschizophrenic computer diagnosis was given to a number of patients diagnosed schizophrenic by clinicians, but the reverse rarely occurred. Was this due to the computer program, the MSER, clinicians, or other factors? These questions have heightened relevance in light of the imminence of Professional Standards Review Organization (PSRO).20 Hospitals may be required to establish definitive operational diagnostic criteria and correlated treatments in order to maintain accreditation and be reimbursed by third-party payers. This study investigated these diagnostic discrepancies in order to ascertain what specific criteria could be used in making a schizophrenic diagnosis in hospitalized patients. Secondarily, the study sought to shed further light on whether such a computer system could be useful as an adjunctive diagnostic modality to pinpoint difficult cases.  相似文献   
103.

Background

Patients in hospitals and nursing homes are at risk for the development of often preventable adverse events. Guidelines for the prevention of many types of adverse events are available, however compliance with these guidelines appears to be lacking. As a result many patients do not receive appropriate care. We developed a patient safety program that allows organisations to implement multiple guidelines simultaneously and therefore facilitates guideline use to improve patient safety. This program was developed for three frequently occurring nursing care related adverse events: pressure ulcers, urinary tract infections and falls. For the implementation of this program we developed educational activities for nurses as a main implementation strategy.

Objectives

The aim of this study is to describe the effect of interactive and tailored education on the knowledge levels of nurses.

Design

A cluster randomised trial was conducted between September 2006 and July 2008.

Settings

Ten hospital wards and ten nursing home wards participated in this study. Prior to baseline, randomisation of the wards to an intervention or control group was stratified for centre and type of ward.

Participants

All nurses from participating wards.

Methods

A knowledge test measured nurses’ knowledge on the prevention of pressure ulcers, urinary tract infections and falls, during baseline en follow-up. The results were analysed for hospitals and nursing homes separately.

Results

After correction for baseline, the mean difference between the intervention and the control group on hospital nurses’ knowledge on the prevention of the three adverse events was 0.19 points on a zero to ten scale (95% CI: −0.03 to 0.42), in favour of the intervention group. There was a statistically significant effect on knowledge of pressure ulcers, with an improved mean mark of 0.45 points (95% CI: 0.10-0.81). For the other two topics there was no statistically significant effect. Nursing home nurses’ knowledge did neither improve (0 points, CI: −0.35 to 0.35) overall, nor for the separate subjects.

Conclusion

The educational intervention improved hospital nurses’ knowledge on the prevention of pressure ulcers only. More research on long term improvement of knowledge is needed.

Trial registration

ClinicalTrials.gov ID [NCT00365430].  相似文献   
104.
盛菲  李文 《生殖与避孕》2017,(6):511-514
基因组印记是指来源于双亲源性的等位基因只有一方表达,这些单亲源性表达的等位基因被称为印记基因。许多研究表明印记基因在胎盘中广泛存在,与胎盘的生长和发育以及母、胎间的营养物质交换等密切相关。而分析印记基因的功能有助于理解为何在哺乳动物的发育过程中基因会发生印记以及印记基因对发育的意义,相关印记基因的研究为理解人类疾病提供了新的角度,包括低体质量出生儿、遗传代谢性疾病以及妊娠并发症如先兆子痫、妊娠期糖尿病等等。因此本综述将从表观遗传角度探讨基因组印记与胎盘发育的关系。  相似文献   
105.
Congenital long-QT syndrome (LQTS) is an inherited cardiac disorder with a disturbance in repolarization characterized by a prolonged QT interval on the surface electrocardiogram and life-threatening ventricular tachycardia. Publications from the International LQTS Registry have provided information that the cardiac risk may be influenced by gender, genotype, exposure to arrhythmia triggers, and previous cardiac events. In children, early-onset of disease, changes in life style, and medical treatment is a sensitive issue and significant, gender-related differences of a first life-threatening event were reported. Thus, we investigated the clinical features of a large genotyped population of LQTS-index children (age ≤16 years) upon a single-center experience and determined risk factors for symptoms. Of 83 children [mean corrected QT interval (QTc) 510 ± 74 ms], 89% had LQT1, -2, or -3. Nine patients (11%) were identified as having Jervell and Lange-Nielsen syndrome. Among symptomatic children (n = 51, 61%), syncope was the most prevalent symptom at initial presentation (49%); however, aborted cardiac arrest (ACA) occurred in 33% and sudden cardiac death (SCD) in 18%, respectively, as the initial manifestation. During a mean follow-up period of 5.9 ± 4.7 years, 31% of the children developed symptoms while on therapy (86% syncope, 9% ACA, 5% SCD). Statistical analyses of risk factors for cardiac events showed that the QTc >500 ms was a strong and significant predictor for cardiac events during follow-up (p = 0.02). Furthermore, a prior syncope [hazard ratio (HR), 4.05; 95% confidence interval (CI), 1.1 to 15.0; p = 0.03] or an ACA (HR, 11.7; 95% CI, 3.1 to 43.4; p = <0.001) identified children with an increased risk for recurrent cardiac events compared to asymptomatic LQT children. LQTS-index children manifest with a high percentage of severe symptoms. Among presently validated risk factors for LQTS, a QTc interval >500 ms and a history of prior syncope or ACA were strong predictors for recurrent cardiac events.  相似文献   
106.
AIM: To review the safety (infection, perforation) and efficacy (expulsion, continuation rates, pregnancy) of intrauterine device (IUD) insertion in the postpartum period. METHODS: MEDLINE, PubMed and Google Scholar were searched for randomized controlled trials and prospective cohort studies of IUD insertions at different times during the postpartum period. Time of insertion during the postpartum period was documented specifically, immediate post placenta period (within 10 min), early post placenta period (10 min to 72 h), and delayed/interval period (greater than 6 wk). Other study variables included mode of delivery, vaginal vs cesarean, manual vs use of ring forceps to insert the IUD. RESULTS: IUD insertion in the immediate postpartum (within 10 min of placental delivery), early postpartum (10 min up to 72 h) and Interval/Delayed (6 wk onward) were found to be safe and efficacious. Expulsion rates were found to be highest in the immediate postpartum groups ranging from 14% to 27%. Immediate post placental insertion found to have expulsion rates that ranged from 3.6% to 16.2%. Expulsion rate was significantly higher after insertion following vaginal vs cesarean delivery. The rates of infection, perforation and unplanned pregnancy following postpartum IUD insertion are low. Method of insertion such as with ring forceps, by hand, or another placement method unique to the type of IUD did not show any significant difference in expulsion rates. Uterine perforations are highest in the delayed/interval IUD insertion groups.Breastfeeding duration and infant development are not affected by delayed/interval insertion of the non-hormonal (copper) IUD or the Levonorgestrel IUD. Timing of the Levonorgestrel IUD insertion may affect breastfeeding. CONCLUSION: IUD insertion is safe and efficacious during the immediate postpartum, early postpartum and delayed postpartum periods. Expulsion rates are highest after vaginal delivery and when inserted during the immediate postpartum period. IUD associated infection rates were not increased by insertion during the postpartum period over interval insertion rates. There is no evidence that breastfeeding is negatively affected by postpartum insertion of copper or hormone-secreting IUD. Although perforation rates were higher when inserted after lactation was initiated. Randomized controlled trials are needed to further elucidate the consequence of lactation on postpartum insertion. Despite the concerns regarding expulsion, perforation and breastfeeding, current evidence indicates that a favorable risk benefit ratio in support of postpartum IUD insertion. This may be particularly relevant for women for whom barriers exist in achieving desired pregnancy spacing.  相似文献   
107.
Kappa opioid receptors stimulation with U50,488 is known to modulate behaviors during the early postnatal period, but the specific neuroanatomical locus of many of these effects is unexplored. In the present study, we infused U50,488 into the midbrain periaqueductal gray (PAG) and investigated the effects of this drug on behavior and heart rate of 1-, 2-, and 3-week-old rats. U50,488 increased activity most potently in 1- and 2-week-old subjects. Ultrasonic vocalization (USV) production was increased in 1-week-old subjects, but not in 2- or 3-week-old pups. Heart rate changes were similarly seen in younger aged subjects. At 1 week, U50,488 decreased heart rate, but at 2 weeks it increased heart rate. There was no effect of this drug on heart rate at 3 weeks. At 1 week, USVs were more potently elicited from dorsal than lateral PAG infusion sites. No other site-specific effects within the PAG were seen. The age-related decline in behavioral effects elicited by U50,488 is consistent with other published reports, and to the extent that kappa receptor activity mediates infant separation responses, implicates the PAG as a modulator of those responses.  相似文献   
108.
Different anterosuperior aspects of the glenoid labrum have already been described and are thought to be normal anatomical variations. The goals of this study were first to characterize these anterosuperior labral morphologies and then to analyze their variations in function of the patients’ age. One hundred shoulder arthroscopies were recorded to study the macroscopic characteristics of the anterosuperior labrum of the glenohumeral joint and its relationships with the proximal insertion of the tendon of the long head of the biceps. Then, patients were divided into two groups in function of their age (below and over 30 years old). Morphological modifications of the labrum were found in function of the age of the patient with an increase of the nonpathologic “mobile labrum” type after 30 years (P=0.0423). Therefore a mobile and loosely attached superior labrum should not always be considered as abnormal, especially in case of patient older than 30 years.  相似文献   
109.
The aim of this study was to explore and compare the magnitude and time-course of the shift in the angle-force curves obtained from maximal voluntary contractions of the elbow flexors, both before and 4 consecutive days after eccentric and isometric exercise. The maximal isometric force of the elbow flexors of fourteen young male volunteers was measured at five different elbow angles between 50° and 160°. Subjects were then divided into two groups: the eccentric group (ECC, n=7) and the isometric group (ISO, n=7). Subjects in the ECC group performed 50 maximal voluntary eccentric contractions of the elbow flexors on an isokinetic dynamometer (30°.s–1), while subjects in the ISO group performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position. Following the ECC and ISO exercise protocols, maximal isometric force at the five angles, muscle soreness, and the relaxed (RANG) and flexed (FANG) elbow angles were measured at 24 h intervals for 4 days. All results were presented as the mean and standard error, and a quadratic curve was used to model the maximal isometric force data obtained at the five elbow angles. This approach not only allowed us to mathematically describe the angle-force curves and estimate the peak force and optimum angle for peak force generation, but also enabled us to statistically compare the shift of the angle-force curves between and within groups. A large and persistent shift of the angle-force curve towards longer muscle lengths was observed 1 day after eccentric exercise (P<0.01). This resulted in a ~16° shift of the optimum angle for force generation, which remained unchanged for the whole observation period. A smaller but also persistent shift of the angle-force curve was seen after isometric exercise at long muscle length (P<0.05; shift in optimum angle ~5°). ECC exercise caused more muscle damage than ISO exercise, as indicated by the greater changes in RANG and ratings of muscle soreness (P<0.05). It was suggested that the shift in the angle-force curve was proportional to the degree of muscle damage and may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle.  相似文献   
110.
We studied the variation from the simultaneous contraction of the normal left ventricle (LV). The pattern of the contraction along the LV long axes was assessed on the LV free wall on seven guinea pig hearts in situ with ultra fast video system and epicardial markers by means of the latitude and the size of the areas defined by markers. We found that the contraction occurs as a continuous contraction wave from the apex towards the base, which might yield functional adaptation of these two regions to diastolic and systolic function, respectively.  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