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   886篇
  免费   66篇
  国内免费   5篇
耳鼻咽喉   5篇
儿科学   22篇
妇产科学   18篇
基础医学   135篇
口腔科学   36篇
临床医学   85篇
内科学   247篇
皮肤病学   9篇
神经病学   95篇
特种医学   13篇
外科学   104篇
综合类   5篇
预防医学   50篇
眼科学   38篇
药学   52篇
肿瘤学   43篇
  2024年   1篇
  2023年   16篇
  2022年   27篇
  2021年   74篇
  2020年   43篇
  2019年   33篇
  2018年   35篇
  2017年   24篇
  2016年   38篇
  2015年   45篇
  2014年   51篇
  2013年   50篇
  2012年   81篇
  2011年   92篇
  2010年   42篇
  2009年   26篇
  2008年   49篇
  2007年   54篇
  2006年   45篇
  2005年   37篇
  2004年   50篇
  2003年   22篇
  2002年   18篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
  1993年   1篇
排序方式: 共有957条查询结果,搜索用时 843 毫秒
101.
102.
103.
A subset of renal cell carcinomas (RCCs) is characterized by t(6;11)(p21;q12), which results in fusion of the untranslated Alpha (MALAT1) gene to the TFEB gene. Only 21 genetically confirmed cases of t(6;11) RCCs have been reported. This neoplasm typically demonstrates a distinctive biphasic morphology, comprising larger epithelioid cells and smaller cells clustered around basement membrane material; however, the full spectrum of its morphologic appearances is not known. The t(6;11) RCCs differ from most conventional RCCs in that they consistently express melanocytic immunohistochemical (IHC) markers such as HMB45 and Melan A and the cysteine protease cathepsin K but are often negative for epithelial markers such as cytokeratins. TFEB IHC has been proven to be useful to confirm the diagnosis of t(6;11) RCCs in archival material, because native TFEB is upregulated through promoter substitution by the gene fusion. However, IHC is highly fixation dependent and has been proven to be particularly difficult for TFEB. A validated fluorescence in situ hybridization (FISH) assay for molecular confirmation of the t(6;11) RCC in archival formalin-fixed, paraffin-embedded material has not been previously reported. We report herein the development of a break-apart TFEB FISH assay for the diagnosis of t(6;11)(p21;q12) RCCs. We validated the assay on 4 genetically confirmed cases and 76 relevant expected negative control cases and used the assay to report 8 new cases that expand the clinicopathologic spectrum of t(6;11) RCCs. An additional previously reported TFEB IHC-positive case was confirmed by TFEB FISH in 46-year-old archival material. In conclusion, TFEB FISH is a robust, clinically validated assay that can confirm the diagnosis of t(6;11) RCC in archival material and should allow a more comprehensive clinicopathologic delineation of this recently recognized neoplastic entity.  相似文献   
104.
Hemorrhagic fever with renal syndrome (HFRS) is a zoonotic infectious disease caused by Hantaviruses, a group of RNA viruses belonging to the Bunyaviridae family. Humans may get the disease by contamination with excreta of carrier rodents. The disease typically manifests with the triad fever-thrombocytopenia-acute kidney injury (AKI). Although its global prevalence seems to be increasing, Hantavirus infection is still commonly overlooked, because of its clinical polymorphism and non-specific symptoms, particularly in mild cases. Until recently, the disease was virtually unknown in Romania, due to lack of physicians' awareness and of adequate laboratory diagnostic techniques. In this article, we present the first six cases of HFRS diagnosed in our country, based on serology testing. We review the existing literature on HFRS and discuss our findings in comparison with other reports. All our patients presented with fever, flu syndrome, bleeding, gastrointestinal symptoms, and oliguria. Among laboratory abnormalities, elevated serum creatinine and liver enzymes, high C-reactive protein, leukocytosis, low platelet count, and hematuria were constantly seen. Five patients required hemodialysis. All patients survived and five of them completely recovered their renal function, while only one patient retained a mild impairment of the glomerular filtration rate. From a clinical viewpoint, we believe that Hantavirus infection should be considered in all patients presenting with fever, thrombocytopenia, and AKI, when specific serology testing would be indicated. From a public health perspective, we suggest that future efforts in our country should be directed toward (1) increasing the understanding and the awareness of this disease among health care professionals, (2) educating the population at risk on the application of prophylactic measures, (3) expanding the availability of diagnostic laboratory tools, and (4) developing research on national zoonotic virus reservoirs.  相似文献   
105.
106.
Increasing antimicrobial resistance reduces treatment options for implant-associated infections caused by methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the activity of fosfomycin alone and in combination with vancomycin, daptomycin, rifampin, and tigecycline against MRSA (ATCC 43300) in a foreign-body (implantable cage) infection model. The MICs of the individual agents were as follows: fosfomycin, 1 μg/ml; daptomycin, 0.125 μg/ml; vancomycin, 1 μg/ml; rifampin, 0.04 μg/ml; and tigecycline, 0.125 μg/ml. Microcalorimetry showed synergistic activity of fosfomycin and rifampin at subinhibitory concentrations against planktonic and biofilm MRSA. In time-kill curves, fosfomycin exhibited time-dependent activity against MRSA with a reduction of 2.5 log10 CFU/ml at 128 × the MIC. In the animal model, planktonic bacteria in cage fluid were reduced by <1 log10 CFU/ml with fosfomycin and tigecycline, 1.7 log10 with daptomycin, 2.2 log10 with fosfomycin-tigecycline and fosfomycin-vancomycin, 3.8 log10 with fosfomycin-daptomycin, and >6.0 log10 with daptomycin-rifampin and fosfomycin-rifampin. Daptomycin-rifampin cured 67% of cage-associated infections and fosfomycin-rifampin cured 83%, whereas all single drugs (fosfomycin, daptomycin, and tigecycline) and rifampin-free fosfomycin combinations showed no cure of MRSA cage-associated infections. No emergence of fosfomycin resistance was observed in animals; however, a 4-fold increase in fosfomycin MIC (from 2 to 16 μg/ml) occurred in the fosfomycin-vancomycin group. In summary, the highest eradication of MRSA cage-associated infections was achieved with fosfomycin in combination with rifampin (83%). Fosfomycin may be used in combination with rifampin against MRSA implant-associated infections, but it cannot replace rifampin as an antibiofilm agent.  相似文献   
107.
The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of εtot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.  相似文献   
108.
The purpose of this study is to verify whether acute pre-treatment with alprazolam (ALP), a benzodiazepine that inhibits HPA secretion in normal subjects, could better characterize patients with subclinical Cushing’s syndrome (SCS) than the 1-mg dexamethasone test (DST). In 22 patients with SCS, 10 with overt Cushing’s syndrome (CS), 11 with non-functioning adrenal incidentalomas (NF) and 14 normal subjects (NS) we studied the effect of ALP (1 mg, p.o. at 2300 hours) on cortisol levels after 1-mg DST. Cortisol levels (mean ± SEM) after DST were lower (P = 0.012) in SCS (3.9 ± 0.3 μg/dl) than in overt CS (10.4 ± 1.9 μg/dl), while they were higher (P = 0.0005) than in NF (1.1 ± 0.1 μg/dl) and NS (1.5 ± 0.1 μg/dl). After ALP pre-treatment, cortisol levels further decreased (P = 0.004) in SCS (3.0 ± 0.3 μg/dl), but neither in CS (9.3 ± 1.3 μg/dl) nor in NF (1.3 ± 0.1 μg/dl) and in NS (1.3 ± 0.1 μg/dl). In SCS, cortisol levels after ALP + 1-mg DST persisted lower (P = 0.0005) than those in CS, but higher (P = 0.0005) than those in NF and NS. Considering individual cases, ALP pre-treatment reduced cortisol levels <3 and <1.8 μg/dl in 50 and 23 % of SCS patients, respectively. ALP amplifies the cortisol inhibition exerted by 1-mg DST in patients with SCS but not in those with CS. The clinical usefulness of ALP to increase the sensitivity of 1-mg DST to identify true autonomous cortisol release in patients with adrenal incidentalomas as well as to predict different clinical outcomes remains to be clarified.  相似文献   
109.
In this paper we demonstrate the combination of supported membranes and so-called flat microfluidics, which enables one to manipulate liquids on flat chip surfaces via “inverse piezoelectric effect”. Here, an alternating external electric field applied to the inter-digital transducers excites a surface acoustic wave on a piezoelectric substrate. Employing lithographic patterning of self-assembled monolayers of alkoxysilanes, we successfully confine a free-standing, hemi-cylindrical channel with the volume of merely 7 µL . The experimentally determined maximum flow velocity scales linearly with the acoustic power, suggesting that our current setup can drive liquids at the speed of up to 7 cm/s (corresponding to a shear rate of 280 s−1) without applying high pressures using a fluidic pump. After the establishment of the functionalization of fluidic chip surfaces with supported membranes, we deposited asymmetric supported membranes displaying well-defined mannose domains and monitored the dynamic adhesion of E. Coli HB101 expressing mannose-binding receptors. Despite of the further technical optimization required for the quantitative analysis, the obtained results demonstrate that the combination of supported membranes and flat fluidics opens a large potential to investigate dynamic adhesion of cells on biofunctional membrane surfaces with the minimum amount of samples, without any fluidic pump.  相似文献   
110.
In rheumatic diseases there can appear deteriorations of the thrombocytes number in the sense of increase or decrease of this number.Thrombocytosis has 3 major causes: (1) reactive or secondary thrombocytosis; (2) family thrombocytosis and (3) clonal thrombocytosis. Thrombocytopenia, that is, decrease of the thrombocytes number below 150000/mmc is unusually in rheumatic diseases. Their mechanism of production can be central and peripheral. In the connective tissue disorders and vasculitis thrombocytopenia can has different causes: (1) decrease thrombocytes production; (2) splenic platelets sequestration; (3) peripheral platelets consumption; (4) peripheral immune mediated destruction of platelets. Thrombocytopenia is present in the following rheumatic diseases: systemic lupus erythematosus, antiphospholipid syndrome, rheumatoid arthritis, Felty syndrome, vasculitis. Steroids are the conventional first line therapy for immune thrombocytopenia. Corticosteroid resistance can develop as a result of deteriorations that appear to the any level of pathway action of corticosteroids.  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