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   2910篇
  免费   163篇
  国内免费   31篇
耳鼻咽喉   30篇
儿科学   56篇
妇产科学   47篇
基础医学   425篇
口腔科学   48篇
临床医学   310篇
内科学   445篇
皮肤病学   108篇
神经病学   206篇
特种医学   251篇
外科学   243篇
综合类   8篇
预防医学   147篇
眼科学   40篇
药学   286篇
中国医学   56篇
肿瘤学   398篇
  2023年   23篇
  2022年   79篇
  2021年   83篇
  2020年   60篇
  2019年   60篇
  2018年   58篇
  2017年   77篇
  2016年   100篇
  2015年   114篇
  2014年   140篇
  2013年   174篇
  2012年   259篇
  2011年   241篇
  2010年   150篇
  2009年   130篇
  2008年   187篇
  2007年   153篇
  2006年   129篇
  2005年   147篇
  2004年   114篇
  2003年   100篇
  2002年   77篇
  2001年   70篇
  2000年   68篇
  1999年   62篇
  1998年   19篇
  1997年   18篇
  1996年   8篇
  1995年   11篇
  1994年   4篇
  1993年   10篇
  1992年   22篇
  1991年   25篇
  1990年   15篇
  1989年   21篇
  1988年   11篇
  1987年   11篇
  1986年   8篇
  1985年   5篇
  1984年   8篇
  1983年   6篇
  1978年   5篇
  1972年   4篇
  1971年   4篇
  1970年   3篇
  1969年   3篇
  1968年   5篇
  1966年   2篇
  1965年   2篇
  1962年   2篇
排序方式: 共有3104条查询结果,搜索用时 15 毫秒
991.

Background

Combined treatment with a bisphosphonate and vitamin D has been proposed for postmenopausal osteoporosis. A new, fixed-dose combination tablet of ibandronate plus vitamin D3 has been developed for monthly administration to treat postmenopausal osteoporosis.

Objectives

The main objective of the present study was to compare the pharmacokinetics of vitamin D3 administered in 2 forms: a newly developed ibandronate 150-mg/vitamin D3 24,000-IU tablet (DP-R206, test drug) and a stand-alone vitamin D3 24,000-IU tablet (reference drug). A secondary objective was to evaluate the safety and tolerability of DP-R206 in healthy adult male Korean volunteers.

Methods

This study was a single-dose, open-label, randomized-sequence, 2-treatment, 2-way crossover trial. Blood samples were collected from 24 hours’ predose to 120 hours’ postdose. The plasma concentrations of vitamin D3 were analyzed by using a validated HPLC-MS/MS method. Pharmacokinetic parameters were calculated, and the 90% CIs of the ratios of the geometric means of the parameters were determined from the logarithmically transformed data by using ANOVA.

Results

Thirty-sex healthy adult male Korean volunteers with a mean (SD) age of 25.8 (2.7) years, a mean height of 174.0 (5.9) cm, and a mean weight of 69.1 (6.2) kg were enrolled; 29 participants completed the study. The 90% CIs of the ratios of the geometric means (test drug/reference drug) of the baseline-corrected Cmax, AUC0–last, and AUC0–∞ values were 0.93 to 1.24, 0.89 to 1.19, and 0.87 to 1.18, respectively. The 90% CIs of the ratios of the geometric means (test drug/reference drug) of the baseline-uncorrected Cmax, AUC0–last, and AUC0–∞ values were 0.93 to 1.24, 0.88 to 1.19, and 0.87 to 1.18, respectively. Eighty-four adverse events (AEs) were reported in 24 of 32 subjects receiving DP-R206, and 14 AEs were reported in 8 of 29 subjects receiving the vitamin D3 24,000-IU tablet. All of the subjects who experienced AEs recovered without sequelae, and no serious AEs were observed.

Conclusions

The vitamin D3 pharmacokinetics were similar for DP-R206 and the 24,000-IU vitamin D3 tablet. DP-R206 was well tolerated. ClinicalTrials.gov identifier: NCT01577849.  相似文献   
992.
The purpose of this study was to investigate the association of the Singh index, cortical thickness index (CTI) and calcar-to-canal (CC) ratio with bone mineral density (BMD) as well as their relationship with physical parameters [age, gender, height, and body mass index (BMI)] in order to assess their potential as an indirect indicator of osteoporosis. BMD, Singh index, CTI and CC ratio as well as the physical parameters were obtained from hip radiographs and clinical records of 140 Korean adults. Linear relationships between the areal BMD of the femoral neck and the parameters as well as between each parameter were obtained. To determine the association between BMD and the radiological parameters, multiple regression analyses were performed after adjusting for the four physical parameters. The CTI was positively associated with BMD (p?=?0.040), whereas the Singh index (p?=?0.209) and CC ratio (p?=?0.655) were not. The CTI was negatively associated with age (p?=?0.02) and positively associated with height (p?=?0.0001) and BMI (p?=?0.001). The CC ratio was also positively associated with age (p?=?0.0001) and negatively associated with height (p?=?0.033). In conclusion, of three parameters available from plain radiograph (age, height, BMI), only CTI was significantly associated with BMD. CTI can provide a tool for rapid assessment of osteoporosis from plain hip radiographs.  相似文献   
993.
Aranda J  Motiejunaite R  Im E  Kazlauskas A 《Diabetes》2012,61(5):1225-1233
The objectives of this study were to investigate how diabetes mellitus (DM) influences responsiveness of retinal neovessels to lysophosphatidic acid (LPA) and to elucidate the underlying mechanism. To this end, we used an ex vivo assay in which neovessels sprouted from retinal explants (isolated from either control or DM mice) when cultured between two layers of collagen and in the presence of vascular endothelial growth factor-A. While DM had no effect on the formation of neovessels, it prevented LPA-induced regression. High-glucose (HG) treatment of retinal explants mimicked the DM phenotype. Similarly, primary retinal endothelial cells (RECs), which were subjected to HG treatment, organized into tubes that were resistant to LPA. HG caused LPA resistance within RECs by elevating ROS, which activated Src-family kinases that stimulated the extracellular signal-related kinase (Erk) pathway, which antagonized LPA-mediated signaling events that were required for regression. This ROS/Src/Erk pathway mechanism appeared to be the same route by which DM induced LPA resistance of retinal neovessels. We conclude that DM/HG reprograms signaling pathways in RECs to induce a state of LPA resistance.  相似文献   
994.
To date, most EEG-based brain–computer interface (BCI) studies have focused only on enhancing BCI performance in such areas as classification accuracy and information transfer rate. In practice, however, test–retest reliability of the developed BCI systems must also be considered for use in long-term, daily life applications. One factor that can affect the reliability of BCI systems is the slight displacement of EEG electrode locations that often occurs due to the removal and reattachment of recording electrodes. The aim of this study was to evaluate and compare various feature extraction methods for motor-imagery-based BCI in terms of robustness to slight changes in electrode locations. To this end, EEG signals were recorded from three reference electrodes (Fz, C3, and C4) and from six additional electrodes located close to the reference electrodes with a 1-cm inter-electrode distance. Eight healthy participants underwent 180 trials of left- and right-hand motor imagery tasks. The performance of four different feature extraction methods [power spectral density (PSD), phase locking value (PLV), a combination of PSD and PLV, and cross-correlation (CC)] were evaluated using five-fold cross-validation and linear discriminant analysis, in terms of robustness to electrode location changes as well as regarding absolute classification accuracy. The quantitative evaluation results demonstrated that the use of either PSD- or CC-based features led to higher classification accuracy than the use of PLV-based features, while PSD-based features showed much higher sensitivity to changes in EEG electrode location than CC- or PLV-based features. Our results suggest that CC can be used as a promising feature extraction method in motor-imagery-based BCI studies, since it provides high classification accuracy along with being little affected by slight changes in the EEG electrode locations.  相似文献   
995.
ABSTRACT

Few studies have investigated language recovery patterns and the mechanisms of crossed bilingual aphasia following a subcortical stroke. In particular, Korean-Japanese crossed bilingual aphasia has not been reported. A 47-year-old, right-handed man was diagnosed with an extensive right basal ganglia hemorrhage. He was bilingual, fluent in both Korean and Japanese. After his stroke, the patient presented with crossed aphasia. We investigated changes in the Korean (L1) and Japanese (L2) language recovery patterns. Both Korean and Japanese versions of the Western Aphasia Battery (WAB) were completed one month after the stroke, and functional magnetic resonance imaging (fMRI) was performed using picture-naming tasks. The WAB showed a paradoxical pattern of bilingual aphasia, with an aphasia quotient (AQ) of 32 for Korean and 50.6 for Japanese, with Broca’s aphasia. The patient scored better in the Japanese version of all domains of the tests. The fMRI study showed left lateralized activation in both language tasks, especially in the inferior frontal gyrus. After six months of language therapy targeting L1, the Korean-WAB score improved significantly, while the Japanese-WAB score showed slight improvement. In this case, the subcortical lesion contributed to crossed bilingual aphasia more highly affecting L1 due to loss of the cortico-subcortical control mechanism in the dominant hemisphere. The paradoxical pattern of bilingual aphasia disappeared after lengthy language therapy targeting L1, and the therapy effect did not transfer to L2. Language recovery in L1 might have been accomplished by reintegrating language networks, including the contralesional language homologue area in the left hemisphere.  相似文献   
996.
We investigated the efficacy and tolerability of various anticholinergics in Korean children with non-neurogenic overactive bladder (OAB). A total of 326 children (males:females= 157:169) aged under 18 yr (mean age 7.3±2.6 yr) who were diagnosed with OAB from 2008 to 2011 were retrospectively reviewed. The mean duration of OAB symptoms before anticholinergic treatment was 16.9±19.0 months. The mean duration of medication was 5.6±7.3 months. Urgency urinary incontinence episodes per week decreased from 1.9±3.1 to 0.4±1.5 times (P<0.001). The median voiding frequency during daytime was decreased from 9.2±5.4 to 6.3±4.2 times (P<0.001). According to 3-day voiding diaries, the maximum and average bladder capacity were increased from 145.5±66.9 to 196.8±80.3 mL and from 80.8±39.6 to 121.8±56.5 mL, respectively (P<0.001). On uroflowmetry, maximum flow rate was increased from 17.6±8.4 to 20.5±8.2 mL/sec (P<0.001). Adverse effects were reported in 14 (4.3%) children and six children (1.8%) discontinued medication due to adverse effects. Our results indicate that anticholinergics are effective to improve OAB symptoms and tolerability was acceptable without severe complications in children.  相似文献   
997.
The combined array comparative genomic hybridization plus single-nucleotide polymorphism microarray (CGH+SNP microarray) platform can simultaneously detect copy number alterations (CNA) and copy-neutral loss of heterozygosity (LOH). Eighteen children with acute myeloid leukemia (AML) (n=15) or myelodysplastic syndrome (MDS) (n=3) were studied using CGH+SNP microarray to evaluate the clinical significance of submicroscopic chromosomal aberrations. CGH+SNP microarray revealed CNAs at 14 regions in 9 patients, while metaphase cytogenetic (MC) analysis detected CNAs in 11 regions in 8 patients. Using CGH+SNP microarray, LOHs>10 Mb involving terminal regions or the whole chromosome were detected in 3 of 18 patients (17%). CGH+SNP microarray revealed cryptic LOHs with or without CNAs in 3 of 5 patients with normal karyotypes. CGH+SNP microarray detected additional cryptic CNAs (n=2) and LOHs (n=5) in 6 of 13 patients with abnormal MC. In total, 9 patients demonstrated additional aberrations, including CNAs (n=3) and/or LOHs (n=8). Three of 15 patients with AML and terminal LOH>10 Mb demonstrated a significantly inferior relapse-free survival rate (P=0.041). This study demonstrates that CGH+SNP microarray can simultaneously detect previously cryptic CNAs and LOH, which may demonstrate prognostic implications.

Graphical Abstract

相似文献   
998.
Graphene has been attracting considerable interest in the field of biomedical engineering because graphene and its derivatives are considered to be ideal platforms for supporting cell growth and differentiation. Here we report that graphene promotes the reprogramming of mouse somatic fibroblasts into induced pluripotent stem cells (iPSCs). We constructed a layer of graphene film on a glass substrate and characterized it as a monolayer using Raman spectroscopy. We found that the graphene substrate significantly improved cellular reprogramming efficiency by inducing mesenchymal-to-epithelial-transition (MET) which is known to affect H3K4me3 levels. Thus, our results reveal that a graphene substrate directly regulates dynamic epigenetic changes associated with reprogramming, providing an efficient tool for epigenetic pluripotent reprogramming.  相似文献   
999.
The purpose of this study was to determine the influence of cocultured adipose-derived stromal cells (ASCs) in enhancing the osteogenic differentiation and angiogenesis of bone marrow stromal cells (BMSCs) as well as the underlying mechanism and the optimal ratio. Two in vitro coculture models, segregated cocultures using transwell and mixed cocultures, were employed to assess the indirect and direct effects of coculture respectively. Coculture was carried out for 14 days using 1 × 105 BMSCs and ASCs of variable number. BMSCs, ASCs, or both were seeded in PLGA scaffold and implanted in the subcutaneous tissue of 25 nude mice for in vivo analysis of angiogenesis. To evaluate the orthotopic bone formation, critical size calvarial defects were created on 20 mice, and implanted with hydroxyapatite/β-tricalcium phosphate granules plus BMSCs, ASCs, or both. From both transwell and mixed coculture model, 1 × 105 BMSCs cocultured with 0.5 × 105 ASCs showed significantly greater osteogenic differentiation and mineralization than BMSCs alone. The mixed ASC/BMSC coculture at or above a ratio of 0.5/1 showed increased secretion of vascular endothelial growth factor (VEGF), and induced effective tube formation from human umbilical vein endothelial cells, which were comparable to ASCs. Cytokine profiling assay and gene expression study showed elevated levels of angiogenic factors VEGF and CXCL1, osteogenic factor Wnt5a as well as transforming growth factor (TGF)-βR1 and SMAD3 from BMSCs when cocultured with ASCs. After 5 weeks of implantation, polylactic-co-glycolic acid (PLGA)-ASCs-BMSCs had a number of vascular structures comparable to PLGA-ASCs and significantly greater than PLGA-BMSCs. Calvarial defects treated with ceramic/BMSCs/ASCs had greater area of repair and better reconstitution of osseous structure than the defects treated with ceramic/ASCs or ceramic/BMSCs after 10 weeks. In conclusion, ASCs added to BMSCs promoted osteogenesis and angiogenesis at the optimal ASC/BMSC ratio of 0.5/1.  相似文献   
1000.
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