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   32091篇
  免费   2016篇
  国内免费   152篇
耳鼻咽喉   321篇
儿科学   781篇
妇产科学   800篇
基础医学   4748篇
口腔科学   1882篇
临床医学   2728篇
内科学   7177篇
皮肤病学   982篇
神经病学   2790篇
特种医学   530篇
外科学   2596篇
综合类   128篇
一般理论   21篇
预防医学   3652篇
眼科学   523篇
药学   2556篇
中国医学   192篇
肿瘤学   1852篇
  2024年   42篇
  2023年   381篇
  2022年   869篇
  2021年   1532篇
  2020年   868篇
  2019年   1249篇
  2018年   1516篇
  2017年   1009篇
  2016年   962篇
  2015年   1196篇
  2014年   1571篇
  2013年   1934篇
  2012年   2958篇
  2011年   3117篇
  2010年   1545篇
  2009年   1299篇
  2008年   2140篇
  2007年   2078篇
  2006年   1801篇
  2005年   1581篇
  2004年   1370篇
  2003年   1150篇
  2002年   999篇
  2001年   108篇
  2000年   62篇
  1999年   92篇
  1998年   134篇
  1997年   128篇
  1996年   82篇
  1995年   64篇
  1994年   67篇
  1993年   48篇
  1992年   44篇
  1991年   29篇
  1990年   25篇
  1989年   20篇
  1988年   17篇
  1987年   15篇
  1986年   14篇
  1985年   13篇
  1984年   12篇
  1983年   12篇
  1982年   16篇
  1981年   9篇
  1980年   13篇
  1978年   7篇
  1976年   7篇
  1975年   8篇
  1972年   6篇
  1965年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Several studies have shown that sleep fragmentation not only increases daytime sleepiness, but also deteriorates reaction time. Obstructive sleep apnea syndrome(OSAS)is characterized by interruptions in normal sleep patterns. Nasal Continuous Positive Airway Pressure(nCPAP)is the most frequently used treatment for OSAS. The objective of this investigation was to evaluate changes in daytime sleepiness levels and reaction time in apnea patients after nCPAP treatments of 1 and 3 months. The sample was composed of 51 obstructive sleep apnea patients(47 men and 4 women)with ages ranging between 30 and 65 years of age. Sleep apnea was diagnosed with a cardiorespiratory polygraph of the total hours of sleep. The Epworth Sleepiness Scale was used to assess daytime sleepiness. A BASIC software program was used to measure the simple perceptual reaction times in milliseconds. The results indicated statistically significant decreases in daytime sleepiness levels at 1 month(p?<?.000)and at 3 months(p?<?.000)of treatment. The results also showed statistically significant decreases in reaction times at one month(p?<?.000), as well as at 3 months(p?<?.000)of treatment. Results indicate an improvement in the vigilance levels of obstructive sleep apnea patients after 1 month and 3 months of nCPAP treatment.  相似文献   
992.
Abstract

Objective: The determination of soft signs can be a conducive practice to understand the differential etiology between depression and anxiety. This study aims at examining malleolar hypoesthesia role in distinguishing between patients with generalised anxiety disorder (GAD) and major depression disorder (MDD).

Methods: This study examines the presence of malleolar hypoesthesia in patients with GAD (n?=?47) compared to patients with MDD (n?=?48) and healthy individuals (controls; n?=?99). The Wartenberg wheel, a medical device for neurological use, was employed to determine the presence of hypoesthesia on both sides of the ankles.

Results: The data revealed: i) MDD patients showed higher hypoesthesia than GAD patients (p?=?.008), ii) participants with hypoesthesia had higher anxiety and depression scores than participants without hypoesthesia (all p?<?.001) and iii) logistic regression model indicated that hypoesthesia can be a predictor of MDD relative to GAD diagnosis (Odds Ratio: 17.43 (1.40–217.09; p?=?.026)).

Conclusions: Malleolar hypoesthesia was higher in MDD than GAD. The detection of hypoesthesia may help to investigate the differential etiology between MDD and GAD diagnosis.  相似文献   
993.
Self-directed disgust, a component of self-criticism, may present an important, yet unexplored emotion in the context of nonsuicidal self-injury (NSSI). The aim of this study was to examine the role of self-disgust in NSSI, specifically as a potential mediator in the relations between depression and NSSI as well as sexual abuse and NSSI, and to also better understand characteristics that might differentiate recent and past self-injurers. A total of 549 college students completed measures assessing NSSI, self-disgust, depression, anxiety sensitivity, and physical and sexual abuse. Results indicated self-disgust fully mediated the relation between depressive symptoms and NSSI status and partially mediated the relation between sexual abuse and NSSI status. Additionally, compared to past self-injurers (4.6%; n = 25), recent self-injurers (6.4%; n = 35) endorsed significantly higher self-disgust and depressive symptoms. Self-disgust may be an important component in NSSI and should be addressed in treatment.  相似文献   
994.
Upper limb function impairment is one of the most common sequelae of central nervous system in jury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cannot provide objective evaluation of patient performance and the effec tiveness of therapies. The most common assessment tools are based on rating scales, which are inefficient when measuring small changes and can yield subjective bias. In this study, we designed an inertial sensorbased monitoring system composed of five sensors to measure and analyze the complex movements of the upper limbs, which are common in activities of daily living. We devel oped a kinematic model with nine degrees of freedom to analyze upper limb and head movements in three dimensions. This system was then validated using a commercial optoelectronic system. These findings suggest that an inertial sensorbased motion tracking system can be used in patients who have upper limb impairment through data integration with a virtual realitybased neurorehabili tation system.  相似文献   
995.

OBJECTIVE:

This study evaluated the diagnostic performance of two methods for the detection of influenza virus in immunocompromised transplant patients.

METHODS:

A total of 475 respiratory samples, 236 from patients in a hematopoietic stem cell transplantation program and 239 from kidney transplant patients, were analyzed by a direct fluorescence assay and the Centers for Disease Control real-time polymerase chain reaction protocol for influenza A and B detection.

RESULTS:

Influenza detection using either method was 7.6% in the hematopoietic stem cell transplant group and 30.5% in the kidney transplant patient group. Influenza detection by real-time polymerase chain reaction yielded a higher positive rate compared with fluorescence than that reported by other studies, and this difference was more pronounced for influenza A. The fluorescence assay sensitivity, specificity, positive and negative predictive values, and kappa coefficient were 17.6%, 100%, 1, 0.83, and 0.256, respectively, and lower detection rates occurred in the kidney transplant patients.

CONCLUSIONS:

The real-time polymerase chain reaction performance and the associated turnaround time for a large number of samples support the choice of this method for use in different routine diagnostic settings and influenza surveillance in high-risk patients.  相似文献   
996.

OBJECTIVE:

This research was designed as a pilot proof-of-concept study to evaluate the use of low-dose methadone in post-herpetic neuralgia patients who remained refractory after first and second line post-herpetic neuralgia treatments and had indications for adding an opioid agent to their current drug regimens.

METHODS:

This cross-over study was double blind and placebo controlled. Ten opioid naïve post-herpetic neuralgia patients received either methadone (5 mg bid) or placebo for three weeks, followed by a 15-day washout period and a second three-week treatment with either methadone or placebo, accordingly. Clinical evaluations were performed four times (before and after each three-week treatment period). The evaluations included the visual analogue scale, verbal category scale, daily activities scale, McGill pain questionnaire, adverse events profile, and evoked pain assessment. All patients provided written informed consent before being included in the study. ClinicalTrials.gov: NCT01752699

RESULTS:

Methadone, when compared to placebo, did not significantly affect the intensity of spontaneous pain, as measured by the visual analogue scale. The intensity of spontaneous pain was significantly decreased after the methadone treatment compared to placebo on the category verbal scale (50% improved after the methadone treatment, none after the placebo, p = 0.031). Evoked pain was reduced under methadone compared to placebo (50% improved after the methadone treatment, none after the placebo, p = 0.031). Allodynia reduction correlated with sleep improvement (r = 0.67, p = 0.030) during the methadone treatment. The side effects profile was similar between both treatments.

CONCLUSIONS:

Methadone seems to be safe and efficacious in post-herpetic neuralgia. It should be tried as an adjunctive treatment for post-herpetic neuralgia in larger prospective studies.  相似文献   
997.

OBJECTIVES:

Nasal continuous positive airway pressure is used as a standard of care after extubation in very-low-birth-weight infants. A pressure of 5 cmH2O is usually applied regardless of individual differences in lung compliance. Current methods for evaluation of lung compliance and air distribution in the lungs are thus imprecise for preterm infants. This study used electrical impedance tomography to determine the feasibility of evaluating the positive end-expiratory pressure level associated with a more homogeneous air distribution within the lungs before extubation.

METHODS:

Ventilation homogeneity was defined by electrical impedance tomography as the ratio of ventilation between dependent and non-dependent lung areas. The best ventilation homogeneity was achieved when this ratio was equal to 1. Just before extubation, decremental expiratory pressure levels were applied (8, 7, 6 and 5 cmH20; 3 minutes each step), and the pressure that determined the best ventilation homogeneity was defined as the best positive end-expiratory pressure.

RESULTS:

The best positive end-expiratory pressure value was 6.3±1.1 cmH20, and the mean continuous positive airway pressure applied after extubation was 5.2±0.4 cmH20 (p = 0.002). The extubation failure rate was 21.4%. X-Ray and blood gases after extubation were also checked.

CONCLUSION:

This study demonstrates that electrical impedance tomography can be safely and successfully used in patients ready for extubation to suggest the best ventilation homogeneity, which is influenced by the level of expiratory pressure applied. In this feasibility study, the best lung compliance was found with pressure levels higher than the continuous positive airway pressure levels that are usually applied for routine extubation.  相似文献   
998.
The 22q11.2 Deletion Syndrome (22q11.2DS) is the most common microdeletion syndrome in humans, with a highly variable phenotype. This chromosomal region contains low copy repeat (LCR) sequences that mediate non-allelic homologous recombination which predispose to copy number abnormalities at this locus. This article describes three patients investigated for suspicion of 22q11.2DS presenting atypical copy number abnormalities overlapping or not with the common ~3 Mb deletion. They were investigated by G-banding karyotype, Multiplex-ligation dependent probe amplification (MLPA) and array Genomic Hibridization (aGH). Clinical and molecular data were compared with literature, in order to contribute to genotype–phenotype correlation. Atypical chromosomal abnormalities were detected: 3.6 Mb deletion at 22q11.21-q11.23 between LCRs B–F in patient 1 and approximately 1.5 Mb deletion at 22q11.21-q11.22 between LCRs D–E in patients 2 and 3. The breakpoints detected in patient 1 have not been previously described. These findings exemplify the complexity and genetic heterogeneity observed in 22q11.2 region and corroborates the idea that genetic modifiers contribute to the phenotypic variability observed in proximal and distal 22q11.2 deletion syndromes.  相似文献   
999.

OBJECTIVE:

To evaluate the effects of the levels of glycemic control on the frequency of clinical complications following invasive dental treatments in type 2 diabetic patients and suggest appropriate levels of fasting blood glucose and glycated hemoglobin considered to be safe to avoid these complications.

METHOD:

Type 2 diabetic patients and non-diabetic patients were selected and divided into three groups. Group I consisted of 13 type 2 diabetic patients with adequate glycemic control (fasting blood glucose levels <140 mg/dl and glycated hemoglobin (HbA1c) levels <7%). Group II consisted of 15 type 2 diabetic patients with inadequate glycemic control (fasting blood glucose levels >140 mg/dl and HbA1c levels >7%). Group III consisted of 18 non-diabetic patients (no symptoms and fasting blood glucose levels <100 mg/dl). The levels of fasting blood glucose, glycated HbA1c, and fingerstick capillary glycemia were evaluated in diabetic patients prior to performing dental procedures. Seven days after the dental procedure, the frequency of clinical complications (surgery site infections and systemic infections) was examined and compared between the three study groups. In addition, correlations between the occurrence of these outcomes and the glycemic control of diabetes mellitus were evaluated.

RESULTS:

The frequency of clinical outcomes was low (4/43; 8.6%), and no significant differences between the outcome frequencies of the various study groups were observed (p>0.05). However, a significant association was observed between clinical complications and dental extractions (p = 0.02).

CONCLUSIONS:

Because of the low frequency of clinical outcomes, it was not possible to determine whether fasting blood glucose or glycated HbA1c levels are important for these clinical outcomes.  相似文献   
1000.

OBJECTIVES:

Suppressor of cytokine signaling 3, myxovirus resistance protein and osteopontin gene polymorphisms may influence the therapeutic response in patients with chronic hepatitis C, and an association with IL28 might increase the power to predict sustained virologic response. Our aims were to evaluate the association between myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 gene polymorphisms in combination with IL28B and to assess the therapy response in hepatitis C patients treated with pegylated-interferon plus ribavirin.

METHOD:

Myxovirus resistance protein, osteopontin, suppressor of cytokine signaling 3 and IL28B polymorphisms were analyzed by PCR-restriction fragment length polymorphism, direct sequencing and real-time PCR. Ancestry was determined using genetic markers.

RESULTS:

We analyzed 181 individuals, including 52 who were sustained virologic responders. The protective genotype frequencies among the sustained virologic response group were as follows: the G/G suppressor of cytokine signaling 3 (rs4969170) (62.2%); T/T osteopontin (rs2853744) (60%); T/T osteopontin (rs11730582) (64.3%); and the G/T myxovirus resistance protein (rs2071430) genotype (54%). The patients who had ≥3 of the protective genotypes from the myxovirus resistance protein, the suppressor of cytokine signaling 3 and osteopontin had a greater than 90% probability of achieving a sustained response (p<0.0001). The C/C IL28B genotype was present in 58.8% of the subjects in this group. The sustained virological response rates increased to 85.7% and 91.7% by analyzing C/C IL28B with the T/T osteopontin genotype at rs11730582 and the G/G suppressor of cytokine signaling 3 genotype, respectively. Genetic ancestry analysis revealed an admixed population.

CONCLUSION:

Hepatitis C genotype 1 patients who were responders to interferon-based therapy had a high frequency of multiple protective polymorphisms in the myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 genes. The combined analysis of the suppressor of cytokine signaling 3 and IL28B genotypes more effectively predicted sustained virologic response than IL28B analysis alone.  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