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   869篇
  免费   39篇
  国内免费   12篇
耳鼻咽喉   8篇
儿科学   17篇
妇产科学   16篇
基础医学   144篇
口腔科学   39篇
临床医学   67篇
内科学   212篇
皮肤病学   4篇
神经病学   80篇
特种医学   10篇
外科学   90篇
综合类   1篇
预防医学   64篇
眼科学   3篇
药学   58篇
中国医学   2篇
肿瘤学   105篇
  2024年   2篇
  2023年   4篇
  2022年   18篇
  2021年   33篇
  2020年   18篇
  2019年   34篇
  2018年   17篇
  2017年   18篇
  2016年   19篇
  2015年   31篇
  2014年   40篇
  2013年   56篇
  2012年   68篇
  2011年   53篇
  2010年   38篇
  2009年   35篇
  2008年   52篇
  2007年   79篇
  2006年   69篇
  2005年   75篇
  2004年   40篇
  2003年   30篇
  2002年   36篇
  2001年   8篇
  2000年   3篇
  1999年   6篇
  1998年   3篇
  1997年   4篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   2篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1984年   1篇
  1983年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1973年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有920条查询结果,搜索用时 15 毫秒
911.
This study performed a field trial of a Portuguese version of the University of Washington quality of life questionnaire (UW-QOL, 3rd version), aiming at appraising its ability to identify different patterns of health-related quality of life of patients with oral cancer in Brazil. Patients (N = 100) were interviewed as they were undergoing treatment for oral squamous cell carcinoma at a large Brazilian hospital ("Hospital das Clínicas", School of Medicine, University of S?o Paulo). The results were compared based on categories of socio-demographic and clinical characteristics of the patients. At a one-year follow-up, 20 patients had died, and 24 were considered dropouts. The remaining patients accounted for the longitudinal assessment of modifications in the self report of quality of life. Patients with larger tumours and neoplasms in the posterior part of the mouth presented significantly (p < 0.05) poorer indications of quality of life. Chewing was the poorest rated domain (35.0/100.0), and presented the highest proportion of complaints both at the baseline and at the follow-up assessments. The questionnaire allowed the identification of important contrasts (while comparing clinical characteristics) and similarities (while comparing socio-demographic status) among subsets of respondents, and it can contribute to reduce the impact of treatments and improve subsequent patient management.  相似文献   
912.
BACKGROUND: Although approximately 80% of individuals with alcohol use disorders are chronic smokers and despite reported associations between chronic cigarette smoking and lower cerebral perfusion in nonalcoholics, previous brain perfusion studies with alcoholics did not account for the potential effects of concurrent chronic cigarette smoking. METHODS: One-week-abstinent alcohol-dependent individuals in treatment (ALC) [19 smokers (sALC) and 10 nonsmokers (nsALC)] and 19 healthy light drinking, nonsmoking control participants (nsLD) were scanned with a pulsed arterial spin labeling method to measure cerebral perfusion without an exogenous contrast agent. Studies were performed with 2 different postlabeling delay times (time from labeling pulse to the excitation pulse; PLD=1,500 ms and PLD=1,200 ms) to assess the potential effect of arterial blood transit time on the perfusion. Average gray matter (GM) and white matter (WM) perfusion for the frontal and parietal lobes were calculated for each hemisphere from voxels containing at least 90% GM and 100% WM. RESULTS: At PLD=1,500 ms, multivariate analyses compared ALC (combined sALC and nsALC) with nsLD (p=0.04) and contrasted sALC, nsALC, and nsLD (p=0.006). ALC, as a group, showed 13% lower frontal GM perfusion (p=0.005) and 8% lower parietal GM perfusion than nsLD (p=0.03). With ALC separated into smokers and nonsmokers, sALC showed 19% lower frontal GM perfusion (p=0.001) and 12% lower parietal GM perfusion than nsLD (p=0.004). In sALC, a higher number of cigarettes smoked per day was associated with lower perfusion. Overall, regional perfusion did not differ significantly between nsALC and nsLD. Results obtained with PLD=1,200 ms generally confirmed the 1,500 ms findings. CONCLUSIONS: This study provides preliminary evidence that chronic cigarette smoking adversely affects cerebral perfusion in frontal and parietal GM of 1-week-abstinent alcohol-dependent individuals. These results are in line with our spectroscopic and structural magnetic resonance studies that suggest chronic cigarette smoking compounds the detrimental effects of alcohol dependence on brain neurobiology.  相似文献   
913.
BACKGROUND: Longitudinal studies of brain tissue metabolite recovery in short-term abstinent alcoholics have primarily investigated the frontal lobes and cerebellum with variable results. Preliminary proton magnetic resonance spectroscopic imaging (1H MRSI) suggested that chronic cigarette smoking exacerbates alcohol-induced brain injury in 1-week abstinent alcoholics. However, the potential effects of chronic cigarette smoking on the recovery of alcohol-induced brain injury have not been studied. METHODS: Multislice short-echo time 1H MRSI was used to measure longitudinal changes in common brain metabolites in 25 recovering alcohol-dependent individuals (RA), retrospectively assigned to smoking (n = 14) and nonsmoking (n = 11) subgroups. Recovering alcohol-dependent individuals in longitudinal analyses were studied after approximately 7 and 34 days of abstinence from alcohol. In cross-sectional analyses, 36 RA (19 smokers, 17 nonsmokers) with approximately 34 days of sobriety were compared with 29 light drinkers (LD). Relationships between neurocognition and metabolite concentrations in abstinent RA were also examined. RESULTS: Over 1 month of abstinence from alcohol, RA, as a group, showed significant increases of regional N-acetylaspartate (NAA; marker of neuronal viability) and choline-containing compounds (Cho; marker of cell membrane synthesis/turnover) primarily in frontal and parietal lobes. These increases appeared to be driven by nonsmoking RA. Cross-sectional results indicate that metabolite levels in RA at 35 days of sobriety are not significantly different from those in LD in most regions, except for lower NAA and Cho in parietal WM and subcortical structures. However, metabolite levels at that time appear to be strongly modulated by smoking status. The patterns of metabolite-neurocognition relationships were different for nonsmoking and smoking RA. CONCLUSIONS: Within the first weeks of sobriety, regional brain NAA and Cho levels increased, but metabolite levels did not normalize in all brain regions after 35 days of sobriety. Neurobiologic recovery in RA appeared to be adversely affected by chronic smoking. Greater consideration of the effects of continued cigarette smoking on the neurobiologic and neurocognitive recovery of alcohol-dependent individuals is warranted.  相似文献   
914.
We aimed to collect and analyze available cases of intraoral acantholytic squamous cell carcinoma (aSCC), that consisted of the authors’ cases and cases derived from the existing literature, with an emphasis on the pathological staging and patient outcome. Our research question was whether aSCC is more aggressive than conventional SCC. The literature was searched for documented cases of aSCC involving the intra-oral mucosa, excluding those from the lips and tonsils, and seven new cases were added from our files. The authors compared the obtained aSCC data to existing data for conventional SCC. Fisher Exact or Pearson’s χ2 tests were used for categorical variables. Fifty-five cases of intraoral aSCC were reviewed, of which 48 were retrieved from the literature. Analysis of the published cases was reinforced by contacting the authors of all the papers with incomplete data for further clarifications. The most common sites of aSCC were the tongue (24/55) and the maxilla/maxillary gingiva and/or palate (11/55). The overall survival rate was 36/53 (67.9%) with a mean follow-up period of 22 months against 62.5% for conventional SCC (p = 0.6). No statistically significant difference between the two variants of the tumor with respect to the oral cavity was detected. The differences in age, sex, survival rate, staging, and locations were not statistically significant. Based on the available data from 55 cases, there is no evidence to suggest that aSCC is more aggressive than conventional SCC in intraoral cases.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12105-021-01368-8.  相似文献   
915.
Extrinsic chemiluminescence can be an efficient tool for determining pesticides and fungicides, which do not possess any intrinsic fluorescent signal. On this basis, (3-aminopropyl) trimethoxysilane (APTMS)-coated ZnO (APTMS@ZnO) was synthesized and tested as an extrinsic probe for the fungicide penconazole. Several synthetic routes were probed using either a one-pot or two-steps method, in order to ensure both a green synthetic pathway and a good signal variation for the penconazole concentration. The synthesized samples were characterized using X-ray diffraction (XRD), infrared (IR), Raman and ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM) imaging and associated energy-dispersive X-ray (EDX) analysis. The average size of the synthesized ZnO nanoparticles (NPs) is 54 ± 10 nm, in line with previous preparations. Of all the samples, those synthesized in two steps, at temperatures ranging from room temperature (RT) to a maximum of 40 °C, using water solvent (G-APTMG@ZnO), appeared to be composed of nanoparticles, homogeneously coated with APTMS. Chemiluminescence tests of G-APTMG@ZnO, in the penconazole concentration range 0.7–1.7 ppm resulted in a quenching of the native signal between 6% and 19% with a good linear response, thus indicating a green pathway for detecting the contaminant. The estimated detection limit (LOD) is 0.1 ± 0.01 ppm.  相似文献   
916.
917.
918.
919.
920.
Immunocytochemical studies with a monoclonal anti–HLA–DR antibody were performed on skin sections and keratinocyte (KTC) suspensions obtained from suction blisters of active psoriatic plaques. HLA–DR+ KTCs were found in the plaques of 23 of 38 patients with active psoriasis. Of these 23, 16 had clinical findings typical of psoriatic arthritis (PA); none of the 15 patients who lacked HLA–DR+ KTCs had PA. Although KTC HLA–DR expression was more prevalent in patients with severe skin disease, 7 of the 23 patients with HLA–DR + KTCs in active psoriatic plaques had mild skin disease; 4 of these 7 had PA. Nail pitting or duration of skin disease did not account for increased incidence of PA in patients with HLA–DR+ KTCs. All psoriasis patients with arthritis received nonsteroidal antiinflammatory drug therapy; 14 received additional therapy directed primarily to the cutaneous manifestations of psoriasis. Nine of these noted arthritis improvement with concurrent skin response; however, in 5 patients, arthritis activity increased, despite improvement of the cutaneous disease. Two other patients, treated with methotrexate, also had concurrent skin and joint improvement. These data suggest that psoriasis patients with HLA–DR + KTCs are at increased risk for the development of associated arthritis.  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