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   1415篇
  免费   106篇
  国内免费   5篇
耳鼻咽喉   18篇
儿科学   41篇
妇产科学   20篇
基础医学   178篇
口腔科学   127篇
临床医学   83篇
内科学   357篇
皮肤病学   59篇
神经病学   145篇
特种医学   32篇
外科学   108篇
综合类   9篇
一般理论   1篇
预防医学   131篇
眼科学   21篇
药学   98篇
中国医学   9篇
肿瘤学   89篇
  2023年   11篇
  2022年   30篇
  2021年   79篇
  2020年   44篇
  2019年   62篇
  2018年   72篇
  2017年   41篇
  2016年   50篇
  2015年   64篇
  2014年   69篇
  2013年   92篇
  2012年   123篇
  2011年   143篇
  2010年   63篇
  2009年   46篇
  2008年   79篇
  2007年   73篇
  2006年   39篇
  2005年   42篇
  2004年   28篇
  2003年   25篇
  2002年   21篇
  2001年   12篇
  2000年   13篇
  1999年   9篇
  1992年   10篇
  1991年   11篇
  1990年   6篇
  1989年   10篇
  1988年   14篇
  1987年   14篇
  1986年   7篇
  1985年   8篇
  1984年   6篇
  1983年   5篇
  1981年   4篇
  1980年   5篇
  1979年   9篇
  1978年   6篇
  1977年   3篇
  1976年   11篇
  1975年   5篇
  1973年   4篇
  1972年   3篇
  1971年   4篇
  1970年   7篇
  1968年   7篇
  1967年   9篇
  1966年   4篇
  1965年   4篇
排序方式: 共有1526条查询结果,搜索用时 15 毫秒
31.
International Journal of Clinical Pharmacy - Background Anemia is a clinical condition frequently seen in patients with inflammatory bowel disease, which is responsible for a significant loss of...  相似文献   
32.
It has been demonstrated that histamine interferes with the recruitment, formation and activity of osteoclasts via H1‐ and H2‐receptors. Cimetidine is a H2‐receptor antagonist used for treatment of gastric ulcers that seems to prevent bone resorption. In this study, a possible cimetidine interference was investigated in the number of alveolar bone osteoclasts. The incidence of osteoclast apoptosis and immunoexpression of RANKL (receptor activator of nuclear factor κB ligand) was also evaluated. Adult male rats were treated with 100 mg kg?1 of cimetidine for 50 days (CimG); the sham group (SG) received saline. Maxillary fragments containing the first molars and alveolar bone were fixed, decalcified and embedded in paraffin. The sections were stained by H&E or submitted to tartrate‐resistant acid phosphatase (TRAP) method. TUNEL (terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling) method and immunohistochemical reactions for detecting caspase‐3 and RANKL were performed. The number of TRAP‐positive osteoclasts, the frequency of apoptotic osteoclasts and the numerical density of RANKL‐positive cells were obtained. Osteoclast death by apoptosis was confirmed by transmission electron microscopy (TEM). In CimG, TRAP‐positive osteoclasts with TUNEL‐positive nuclei and caspase‐3‐immunolabeled osteoclasts were found. A significant reduction in the number of TRAP‐positive osteoclasts and a high frequency of apoptotic osteoclasts were observed in CimG. Under TEM, detached osteoclasts from the bone surface showed typical features of apoptosis. Moreover, a significant reduction in the numerical density of RANKL‐positive cells was observed in CimG. The significant reduction in the number of osteoclasts may be due to cimetidine‐induced osteoclast apoptosis. However, RANKL immunoexpression reduction also suggests a possible interference of cimetidine treatment in the osteoclastogenesis.  相似文献   
33.
The development of T cells with a regulatory phenotype after thymus transplantation has not been examined previously in complete DiGeorge anomaly (cDGA). Seven athymic infants with cDGA and non-maternal pretransplantation T cell clones were assessed. Pretransplantation forkhead box protein 3 (Foxp3)+ T cells were detected in five of the subjects. Two subjects were studied in greater depth. T cell receptor variable β chain (TCR-Vβ) expression was assessed by flow cytometry. In both subjects, pretransplantation FoxP3+ and total CD4+ T cells showed restricted TCR-Vβ expression. The development of naive T cells and diverse CD4+ TCR-Vβ repertoires following thymic transplantation indicated successful thymopoiesis from the thymic tissue grafts. Infants with atypical cDGA develop rashes and autoimmune phenomena before transplantation, requiring treatment with immunosuppression, which was discontinued successfully subsequent to the observed thymopoiesis. Post-transplantation, diverse TCR-Vβ family expression was also observed in FoxP3+ CD4+ T cells. Interestingly, the percentages of each of the TCR-Vβ families expressed on FoxP3+ and total CD4+ T cells differed significantly between these T lymphocyte subpopulations before transplantation. By 16 months post-transplantation, however, the percentages of expression of each TCR-Vβ family became significantly similar between FoxP3+ and total CD4+ T cells. Sequencing of TCRBV DNA confirmed the presence of clonally amplified pretransplantation FoxP3+ and FoxP3 T cells. After thymus transplantation, increased polyclonality was observed for both FoxP3+ and FoxP3 cells, and pretransplantation FoxP3+ and FoxP3 clonotypes essentially disappeared. Thus, post-transplantation thymic function was associated with the development of a diverse repertoire of FoxP3+ T cells in cDGA, corresponding with immunological and clinical recovery.  相似文献   
34.
Circulating TFH (cTFH) cells express CXCR5, PD-1, and, when activated, ICOS, and release IL-21. According to the production of IFN-γ, IL-4, and IL-17 and expression of FoxP3, these cells are also classified as cTFH1, cTFH2, cTFH17, and cTFR cells, respectively. This CD4+T-cell subset is pivotal to efficient humoral immunity, and pregnancy appears to favor IgG production. Here, not only pregnancy amplified the in vivo production of anti-HBsAg IgG in HBV immunized women, but the frequency of cTFH cells was directly correlated with estradiol levels. In vitro, pregnancy-related dose of 17-β-estradiol (E2) directly increased the percentage of different cTFH subsets. While E2 and progesterone (P4) increased the proportion of differentiated TFH cells derived from naïve CD4+T-cells, only E2 amplified the release of IL-21 in those cell cultures. In addition, E2 and P4 increased the proportion of memory B cells and plasma cells, respectively. In SEB-activated B/TFH cell co-cultures, E2, in the presence of P4, increased the production of total IgG. Finally, among the hormones, P4 was stronger in upregulating the percentage of IL-10+TFR cells. Collectively, our findings suggested that E2 and P4 cooperate in the humoral immune response by favoring the expansion of different cTFH and B cell subsets.  相似文献   
35.
Objectives:To present the ballistic gelatin as a new material capable of simulating the soft tissues in cone-beam CT (CBCT) images.Methods:CBCT images of three piglet heads were acquired with their soft tissues intact (standard group). Subsequently, the piglet heads were fixed in a container using metallic pins and moulded with acrylic resin; the soft tissues were then removed and replaced by ballistic gelatin, with the same thickness of the original soft tissues. The images were evaluated by two oral radiologists, to check the adaptation on bone surfaces, thickness and density, penetration into large bone cavities and cancellous bone, and the presence of air bubbles using a 5-score scale. Additionally, an objective analysis was carried out by one oral radiologist. For each CBCT scan, three axial reconstructions were selected to represent the mandibular, occlusal, and maxillary levels. The mean and standard deviation (SD) of the grey values were calculated in four regions of interest determined on soft tissue areas and compared by two-way ANOVA.Results:The ballistic gelatin showed subjective scores ranging from good to excellent for all parameters evaluated. There was no significant difference in the mean and SD values of the grey values between ballistic gelatin and the gold standard groups for all levels (p > 0.05). Higher SD values were observed in the occlusal level for both groups (p < 0.05).Conclusions:Ballistic gelatin has visual and objective similarity with the gold standard. Thus, the ballistic gelatin is a promising material capable of simulating soft tissues in CBCT images.  相似文献   
36.
37.
AimTo elucidate the presence of apical periodontitis in the root canal of teeth with secondary/persistent infection, including composition of microbiota, levels of endotoxins and lipoteichoic acid (LTA), and clinical implications of these findings.MethodSamples were collected from root canals of 50 patients who needed endodontic retreatment and had radiographic evidence of apical periodontitis. Microorganisms were identified by using the culture technique and biochemical tests. Nested–polymerase chain reaction (nested-PCR) was used to identify 17 species of specific bacteria. Lipopolysaccharides (LPS) and LTAs were quantified by using, respectively, limulus amebocyte lysate and enzyme-linked immunosorbent assay tests.ResultsBacteria were detected in all samples by culture and molecular methods. A total of 154 gram-positive strains, of 188 strains isolated, were found in the root canals by culture. Enterococcus faecalis and Gemella morbillorum were the most prevalent species identified by the biochemical tests, whereas molecular analyses (nested-PCR) showed a high frequency of P. gingivalis, E. faecalis, and Fusobacterium nucleatum. LPS and LTA were detected in all samples, with mean values being 3.52 EU/mL and 597.83 pg/mL, respectively. Significant statistical correlations were found between levels of LTA and clinical features.ConclusionDespite the prevalence of gram-positives, the microbiota present in secondary/persistent infections showed a large variety of species. Within this diversity, associations were found between specific bacteria and clinical features. In addition, higher levels of LTA were statistically associated with larger periapical radiolucent areas, but no correlation between this feature and LPS was found.  相似文献   
38.
Clinical Oral Investigations - This a cross-sectional study to evaluate the association between oral health findings and ventilator-associated pneumonia (VAP) among critically ill patients in...  相似文献   
39.
The interest in non-invasive brain stimulation techniques is increasing in recent years. Among these techniques, transcranial direct current stimulation (tDCS) has been the subject of great interest among researchers because of its easiness to use, low cost, benign profile of side effects and encouraging results of research in the field. This interest has generated several studies and randomized clinical trials, particularly in psychiatry. In this review, we provide a summary of the development of the technique and its mechanism of action as well as a review of the methodological aspects of randomized clinical trials in psychiatry, including studies in affective disorders, schizophrenia, obsessive compulsive disorder, child psychiatry and substance use disorder. Finally, we provide an overview of tDCS use in cognitive enhancement as well as a discussion regarding its clinical use and regulatory and ethical issues. Although many promising results regarding tDCS efficacy were described, the total number of studies is still low, highlighting the need of further studies aiming to replicate these findings in larger samples as to provide a definite picture regarding tDCS efficacy in psychiatry.  相似文献   
40.
The periorbital subunit is one of the first facial regions to show signs of aging, primarily due to volume depletion of the soft tissue and bony resorption. Surgical and office-based nonsurgical procedures form an important basis for periorbital rejuvenation. It is important to make a detailed clinical evaluation of the patient to indicate the most appropriate procedure to be performed. With the objective of showing a nonsurgical procedure for the rejuvenation of the periorbital area, the authors describe a technique of applying fillers in the upper and lower periorbital regions, paying attention to the anatomy of this facial region and the type of product to be used besides the expected results of the procedure and its possible adverse effects and complications. The nonsurgical rejuvenation of the periorbicular region with hyaluronic acid is a new and innovative technique. In the opinion of the authors, it is a great aesthetic impact area and consequently brings high satisfaction to patients.Maintaining a youthful and pleasant appearance of the face in today’s culture impacts quality of life in many patients. The facial contour remodeling is being revolutionized by new nonsurgical techniques.Facial aging is a complex and dynamic process. All people age differently as a result of imbalance, disharmony, and disproportion of the aging process between the overlying soft tissue and the underlying bony frameworks.1 The upper periorbital subunit is one of the first facial regions to show signs of aging, and even minor changes in its structure and volume can distort the perceived emotions and health of patients.2 An aesthetic and youthful upper periorbital subunit is characterized by a well-defined brow of appropriate height and shape, fullness of the upper periorbit, a crisp and well-defined upper eyelid crease, minimal skin excess, and good skin quality.3,4In the aging process of this facial area, one group of patients displays signs of aging due predominantly to soft tissue ptosis of the upper eyelid, requiring surgical excision. Another group presents with volume depletion of the soft tissue and bony resorption of the orbit. The loss of septal support, leading to brow prolapse and an exacerbation of upper eyelid fullness and congestion, can also contribute to the aging process. This appearance is characterized by deflation of the upper eyelid as well as hollowing and visibility of the supraorbital bony rim, leading to a sunken, hollow, and skeletonized orbit, which can make the patient appear sickly, anorexic, and old. In recent years, modern facial rejuvenation surgery has evolved toward volume restoration in addition to tissue suspension.2Comprehensive analysis of both soft tissue and bony structural changes are essential for the periorbital rejuvenation. Surgical procedures and office-based nonsurgical procedures form an important basis for periorbital rejuvenation, including cosmeceuticals, chemical peels, laser and light treatments, neurotoxins, and fillers. Improved understanding of the pathophysiology of aging and technical advancements in nonsurgical techniques has enabled us to achieve better and more comprehensive improvement for patients.5  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