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   1444篇
  免费   54篇
  国内免费   4篇
耳鼻咽喉   20篇
儿科学   35篇
妇产科学   28篇
基础医学   216篇
口腔科学   14篇
临床医学   104篇
内科学   227篇
皮肤病学   32篇
神经病学   186篇
特种医学   97篇
外科学   254篇
预防医学   59篇
眼科学   19篇
药学   58篇
中国医学   2篇
肿瘤学   151篇
  2023年   8篇
  2022年   9篇
  2021年   12篇
  2020年   13篇
  2019年   25篇
  2018年   27篇
  2017年   17篇
  2016年   35篇
  2015年   29篇
  2014年   39篇
  2013年   58篇
  2012年   122篇
  2011年   96篇
  2010年   71篇
  2009年   73篇
  2008年   96篇
  2007年   105篇
  2006年   104篇
  2005年   70篇
  2004年   84篇
  2003年   89篇
  2002年   84篇
  2001年   15篇
  2000年   4篇
  1999年   11篇
  1998年   18篇
  1997年   19篇
  1996年   11篇
  1995年   8篇
  1994年   11篇
  1993年   15篇
  1992年   8篇
  1990年   4篇
  1989年   5篇
  1980年   3篇
  1944年   3篇
  1939年   3篇
  1938年   3篇
  1933年   3篇
  1929年   3篇
  1928年   4篇
  1927年   3篇
  1926年   6篇
  1925年   7篇
  1924年   3篇
  1923年   6篇
  1922年   4篇
  1921年   2篇
  1920年   3篇
  1913年   3篇
排序方式: 共有1502条查询结果,搜索用时 15 毫秒
31.
Objective: The purpose of this study was to describe the fetal/neonatal cytomegalovirus (CMV) status according to chorionicity and outcome in twin pregnancies diagnosed with CMV.

Methods: An opportunistic diagnosis of CMV infection was performed in a tertiary referral center. All cases diagnosed in twin pregnancies (2006–2011) were included. Prenatal diagnosis was performed by CMV-DNA in the amniotic fluid (AF) of both fetuses only on the evidence of sonographic findings in either one or both twins. Neonatal screening was selectively assessed in symptomatic newborns, preterm, and infants born to HIV-infected mothers. Congenital infection was considered in the presence of CMV-DNA in AF, fetal tissues or newborn urine within the first 2 weeks of life, and symptomatic disease with clinical findings at birth or autopsy.

Results: A total of six twin pregnancies with congenital CMV infection were diagnosed, five dichorionic and one monochorionic diamniotic. Only one sibling was infected among dichorionic pregnancies, two diagnosed prenatally, and three after birth. In the monochorionic pregnancy, the diagnosis was performed prenatally and the two fetuses were infected and severely damaged.

Conclusions: Congenital CMV infection in twins might be related, among other factors, to chorionicity, and in DC twins a non-concordant infection can be expected.  相似文献   
32.
33.

Purpose

To study whether formulation influences biodistribution, necrosis avidity and tumoricidal effects of the radioiodinated hypericin, a necrosis avid agent for a dual-targeting anticancer radiotherapy.

Methods

Iodine-123- and 131-labeled hypericin (123I-Hyp and 131I-Hyp) were prepared with Iodogen as oxidant, and formulated in dimethyl sulfoxide (DMSO)/PEG400 (polyethylene glycol 400)/water (25/60/15, v/v/v) or DMSO/saline (20:80, v/v). The formulations with excessive Hyp were optically characterized. Biodistribution, necrosis avidity and tumoricidal effects were studied in rats (n?=?42) without and with reperfused liver infarction and implanted rhabdomyosarcomas (R1). To induce tumor necrosis, R1-rats were pre-treated with a vascular disrupting agent. Magnetic resonance imaging, tissue-gamma counting, autoradiography and histology were used.

Results

The two formulations differed significantly in fluorescence and precipitation. 123I-Hyp/Hyp in DMSO/PEG400/water exhibited high uptake in necrosis but lower concentration in the lung, spleen and liver (p?<?0.01). Tumor volumes of 0.9?±?0.3 cm3 with high radioactivity (3.1?±?0.3% ID/g) were detected 6 days post-treatment. By contrast, 131I-Hyp/Hypin DMSO/saline showed low uptake in necrosis but high retention in the spleen and liver (p?<?0.01). Tumor volumes reached 2.6?±?0.7 cm3 with low tracer accumulation (0.1?±?0.04%ID/g).

Conclusions

The formulation of radioiodinated hypericin/hypericin appears crucial for its physical property, biodistribution, necrosis avidity and tumoricidal effects.  相似文献   
34.

Background

Obesity has historically been a positive predictor of surgical morbidity, especially in the morbidly obese. The purpose of our study was to compare outcomes of obese patients undergoing laparoscopic cholecystectomy (LC).

Methods

We reviewed 1382 consecutive patients retrospectively who underwent LC for various pathologies from January 2008 to August 2011. Patients were stratified based on the World Health Organization definitions of obesity: nonobese (body mass index [BMI] < 30 kg/m2), obesity class I (BMI 30–34.9 kg/m2), obesity class II (BMI 35–39.9 kg/m2), and obesity class III (BMI ≥ 40 kg/m2). The primary end points were conversion rates and surgical morbidity. The secondary end point was length of stay.

Results

There were significantly more females in the obesity II and III groups (P = 0.0002). American Society of Anesthesiologists scores were significantly higher in the obesity I, II, and III groups compared with the nonobese (P < 0.05; P < 0.01; and P < 0.0001, respectively). Independent predictors of conversion on multivariate analysis (MVA) included age (P = 0.01), acute cholecystitis (P = 0.03), operative time (P < 0.0001), blood loss (P < 0.0001), and fellowship-trained surgeons (P < 0.0001). Independent predictors of intraoperative complications on MVA included age (P = 0.009), white patients (P = 0.009), previous surgery (P = 0.001), operative time (P < 0.0001), and blood loss (P = 0.01). Independent predictors of postoperative complications on MVA included American Society of Anesthesiologists score (P < 0.0001), acute cholecystitis (P < 0.0001), and a postoperative complication (P < 0.0001). BMI was not a predictor of conversions or surgical morbidity. Length of stay was not significantly different between the four groups.

Conclusions

This study demonstrates that overall conversion rates and surgical morbidity are relatively low following LC, even in obese and morbidly obese patients.  相似文献   
35.
Numerous studies suggest that anxious individuals are more hypervigilant to threat in their environment than nonanxious individuals. In the present event-related potential (ERP) study, we sought to investigate the extent to which afferent cortical processes, as indexed by the earliest visual component C1, are biased in observers high in fear of specific objects. In a visual search paradigm, ERPs were measured while spider-fearful participants and controls searched for discrepant objects (e.g. spiders, butterflies, flowers) in visual arrays. Results showed enhanced C1 amplitudes in response to spatially directed target stimuli in spider-fearful participants only. Furthermore, enhanced C1 amplitudes were observed in response to all discrepant targets and distractors in spider-fearful compared with non-anxious participants, irrespective of fearful and non-fearful target contents. This pattern of results is in line with theoretical notions of heightened sensory sensitivity (hypervigilance) to external stimuli in high-fearful individuals. Specifically, the findings suggest that fear facilitates afferent cortical processing in the human visual cortex in a non-specific and temporally sustained fashion, when observers search for potential threat cues.  相似文献   
36.

Background

Few studies have validated bioelectrical impedance analysis (BIA) following bariatric surgery.

Methods

We examined agreement of BIA (Tanita 310) measures of total body water (TBW) and percent body fat (%fat) before (T0) and 12 months (T12) after bariatric surgery, and change between T0 and T12 with reference measures: deuterium oxide dilution for TBW and three-compartment model (3C) for %fat in a subset of participants (n?=?50) of the Longitudinal Assessment of Bariatric Surgery-2.

Results

T0 to T12 median (IQR) change in deuterium TBW and 3C %fat was ?6.4 L (6.4 L) and ?14.8 % (13.4 %), respectively. There were no statistically significant differences between deuterium and BIA determined TBW [median (IQR) difference: T0 ?0.1 L (7.1 L), p?=?0.75; T12 0.2 L (5.7 L), p?=?0.35; Δ 0.35 L(6.3 L), p?=?1.0]. Compared with 3C, BIA underestimated %fat at T0 and T12 [T0 ?3.3 (5.6), p?<?0.001; T12 ?1.7 (5.2), p?=?0.04] but not change [0.7 (8.2), p?=?0.38]. Except for %fat change, Bland-Altman plots indicated no proportional bias. However, 95 % limits of agreement were wide (TBW 15–22 L, %fat 19–20 %).

Conclusions

BIA may be appropriate for evaluating group level response among severely obese adults. However, clinically meaningful differences in the accuracy of BIA between individuals exist.  相似文献   
37.
38.
    
Ohne Zusammenfassung  相似文献   
39.
40.

Background  

Although the health sciences have been observing the negative impact of mass unemployment on health for some time now, health reporting remains fragmentary.  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