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   1459篇
  免费   93篇
  国内免费   3篇
耳鼻咽喉   25篇
儿科学   95篇
妇产科学   9篇
基础医学   176篇
口腔科学   19篇
临床医学   97篇
内科学   207篇
皮肤病学   40篇
神经病学   65篇
特种医学   53篇
外科学   153篇
综合类   304篇
预防医学   81篇
眼科学   8篇
药学   89篇
  1篇
中国医学   5篇
肿瘤学   128篇
  2022年   14篇
  2021年   23篇
  2020年   21篇
  2019年   14篇
  2018年   19篇
  2017年   23篇
  2016年   20篇
  2015年   45篇
  2014年   43篇
  2013年   45篇
  2012年   68篇
  2011年   65篇
  2010年   85篇
  2009年   67篇
  2008年   91篇
  2007年   78篇
  2006年   76篇
  2005年   52篇
  2004年   75篇
  2003年   40篇
  2002年   53篇
  2001年   47篇
  2000年   32篇
  1999年   32篇
  1998年   35篇
  1997年   35篇
  1996年   31篇
  1995年   22篇
  1994年   23篇
  1993年   11篇
  1992年   15篇
  1991年   6篇
  1990年   16篇
  1989年   15篇
  1988年   20篇
  1987年   12篇
  1986年   13篇
  1985年   12篇
  1984年   7篇
  1983年   8篇
  1982年   12篇
  1980年   8篇
  1979年   11篇
  1978年   17篇
  1977年   17篇
  1976年   8篇
  1974年   12篇
  1973年   8篇
  1972年   6篇
  1971年   6篇
排序方式: 共有1555条查询结果,搜索用时 15 毫秒
71.
Introduction : To systematically review the literature on mother‐to‐child transmission in breastfed infants whose mothers received antiretroviral therapy and support the process of updating the World Health Organization infant feeding guidelines in the context of HIV and ART. Methods : We reviewed experimental and observational studies; exposure was maternal HIV antiretroviral therapy (and duration) and infant feeding modality; outcomes were overall and postnatal HIV transmission rates in the infant at 6, 9, 12 and 18 months. English literature from 2005 to 2015 was systematically searched in multiple electronic databases. Papers were analysed by narrative synthesis; data were pooled in random effects meta‐analyses. Postnatal transmission was assessed from four to six weeks of life. Study quality was assessed using a modified Newcastle‐Ottawa Scale (NOS) and GRADE. Results and discussion : Eleven studies were identified, from 1439 citations and review of 72 abstracts. Heterogeneity in study methodology and pooled estimates was considerable. Overall pooled transmission rates at 6 months for breastfed infants with mothers on antiretroviral treatment (ART) was 3.54% (95% CI: 1.15–5.93%) and at 12 months 4.23% (95% CI: 2.97–5.49%). Postnatal transmission rates were 1.08 (95% CI: 0.32–1.85) at six and 2.93 (95% CI: 0.68–5.18) at 12 months. ART was mostly provided for PMTCT only and did not continue beyond six months postpartum. No study provided data on mixed feeding and transmission risk. Conclusions : There is evidence of substantially reduced postnatal HIV transmission risk under the cover of maternal ART. However, transmission risk increased once PMTCT ART stopped at six months, which supports the current World Health Organization recommendations of life‐long ART for all.  相似文献   
72.

Background:

Patellar dislocations are either due to superolateral contracture of the soft tissue or imbalance of the power between the vastus medialis (VM) and the vastus lateralis (VL). The imbalance of muscle power as an etiology of patellar dislocation has not been studied. Hence, we studied the recurrent, habitual and permanent dislocations of the patella with an electromyogram (EMG) of the vastus medialis, vastus lateralis, and pes anserinus, before and after realignment operations, to document the muscle imbalance and effectiveness of the realignment operation.

Materials and Methods:

An electromyographic investigation was carried out on the vastus medialis and vastus lateralis in nine recurrent, 20 habitual, and 13 permanent dislocations of the patella, before and after their realignment operations. Pes anserinus transposition, which acted as a medial stabilizer of the patella, was also investigated with an EMG study, to understand its role on patellar stability at 0°, 30°, 60°, 90°, 120°, 150°, and full flexion of the knee. The age of the patients varied from nine to 30 (mean 15) years. There were 24 males and 18 females. Twenty-six patellar dislocations were on the right and 16 were on the left side.

Results:

Electromyographic pictures reveal subnormal activity of the vastus medialis in all types of dislocations and similar activities of the vastus lateralis in permanent and habitual dislocations recorded pre operatively, which recovered to almost normal values postoperatively, at the mean one-year follow-up. Pes anserinus, which was used for medial stabilization of the patella after its realignment, maintained normal EMG activity before and after the operation.

Conclusion:

This study is significant for understanding the imbalance of muscle activities in patients with an unstable patella, which can be rectified without recurrence after pes anserinus transposition.  相似文献   
73.
74.

Purpose

We examined the relationship between economic, physical, and social characteristics of neighborhoods, where men who have sex with men (MSM) lived and socialized, and symptom scores of depression and generalized anxiety disorder (GAD).

Methods

Participants came from a cross-sectional study of a population-based sample of New York City MSM recruited in 2010–2012 (n?=?1126). Archival and survey-based data were obtained on neighborhoods, where the men lived and where they socialized most often.

Results

MSM who socialized in neighborhoods with more economic deprivation and greater general neighborhood attachment experienced higher GAD symptoms. The relationship between general attachment to neighborhoods where MSM socialized and mental health depended on the level of gay community attachment: in neighborhoods characterized by greater gay community attachment, general neighborhood attachment was negatively associated with GAD symptoms, while in low gay community attachment neighborhoods, general neighborhood attachment had a positive association with GAD symptoms.

Conclusions

This study illustrates the downsides of having deep ties to social neighborhoods when they occur in the absence of broader access to ties with the community of one’s sexual identity. Interventions that help MSM cross the spatial boundaries of their social neighborhoods and promote integration of MSM into the broader gay community may contribute to the reduction of elevated rates of depression and anxiety in this population.
  相似文献   
75.
76.
The disastrous entry of amniotic fluid into the maternal circulation leads to dramatic sequelae of clinical events, characteristically referred to as Amniotic fluid embolism (AFE). The underlying mechanism for AFE is still poorly understood. Unfortunately, this situation has very grave maternal and fetal consequences. AFE can occur during labor, caesarean section, dilatation and evacuation or in the immediate postpartum period. The pathophysiology is believed to be immune mediated which affects the respiratory, cardiovascular, neurological and hematological systems. Undetected and untreated it culminates into fulminant pulmonary edema, intractable convulsions, disseminated intravascular coagulation (DIC), malignant arrhythmias and cardiac arrest. Definite diagnosis can be confirmed by identification of lanugo, fetal hair and fetal squamous cells (squames) in blood aspirated from the right ventricle. Usually the diagnosis is made clinically and by exclusion of other causes. The cornerstone of management is a multidisciplinary approach with supportive treatment of failing organs systems. Despite improved modalities for diagnosing AFE, and better intensive care support facilities, the mortality is still high.  相似文献   
77.
In the present study we describe a novel agent, SoRI-6238 (ethyl 5-amino-3-(3,4-dichlorophenyl)-1,2-dihydropyrido[3,4-b]pyrazin-7-ylcarbamate) that partially inhibits 5-HT transporter (SERT) binding and allosterically modulates SERT function. Membranes were prepared from rat brain. SoRI-6238 partially inhibited SERT binding to brain membranes with a plateau at about 40% of control. SoRI-6238 fully inhibited norepinephrine transporter (NET) and dopamine transporter (DAT) binding with IC(50) values of 12.1 microM and 5.8 microM, respectively. The apparent K(d) of [(125)I]RTI-55 binding to SERT increased, then reached a plateau with increasing concentrations of SoRI-6238. SoRI-6238 fully inhibited [(3)H]5-HT uptake, acting to decrease the V(max) (noncompetitive inhibition). In kinetic experiments, SoRI-6238 slowed the dissociation of [(125)I]RTI-55 from SERT and slowed the initial association rate. We conclude that SoRI-6238 partially inhibits SERT binding and function, most likely via an allosteric mechanism.  相似文献   
78.
Mark AK  高立  杨敏洁 《放射学实践》2006,21(12):1292-1295
青年学者常常在完成资料收集和分析之后对获得的结果充满了激情。然而,在开始写作论文时,这种热情常常锐减。事实也如此,国家级学术会议的论文数远高于最终发表的医学文献数。优秀的研究成果不能发表的原因2大多在于写作新手在开始写作时对写作的认识混乱和畏缩。一般产生畏缩的原因有2个:要么是研究者不知从何着手,要么是不知如何组织文章结构。不过,大部分放射学论文的写作均有规律可寻,在很大程度上是程式化的。本文试图介绍一种可应用于典型放射学论文的逐段写作法。如果初学者能够完成按照本文教授的18段写作,其论文将具有合理的结构,…  相似文献   
79.
80.
The Stiff Elbow     
Elbow motion is essential for upper extremity function to position the hand in space. Unfortunately, the elbow joint is prone to stiffness following a multitude of traumatic and atraumatic etiologies. Elbow stiffness can be diagnosed with a complete history and physical exam, supplemented with appropriate imaging studies. The stiff elbow is challenging to treat, and thus, its prevention is of paramount importance. When this approach fails, non-operative followed by operative treatment modalities should be pursued. Upon initial presentation in those who have minimal contractures of 6-month duration or less, static and dynamic splinting, serial casting, continuous passive motion, occupational/physical therapy, and manipulation are non-operative treatment modalities that may be attempted. A stiff elbow that is refractory to non-operative management can be treated surgically, either arthroscopically or open, to eliminate soft tissue or bony blocks to motion. In the future, efforts to prevent and treat elbow stiffness may target the basic science mechanisms involved. Our purpose was to review the etiologies, classification, evaluation, prevention, operative, and non-operative treatment of the stiff elbow.  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