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   1607篇
  免费   111篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   65篇
妇产科学   32篇
基础医学   253篇
口腔科学   65篇
临床医学   173篇
内科学   258篇
皮肤病学   11篇
神经病学   203篇
特种医学   28篇
外国民族医学   7篇
外科学   237篇
综合类   9篇
预防医学   140篇
眼科学   13篇
药学   85篇
肿瘤学   134篇
  2022年   14篇
  2021年   21篇
  2020年   9篇
  2019年   22篇
  2018年   33篇
  2017年   21篇
  2016年   19篇
  2015年   25篇
  2014年   38篇
  2013年   48篇
  2012年   93篇
  2011年   106篇
  2010年   49篇
  2009年   54篇
  2008年   76篇
  2007年   105篇
  2006年   75篇
  2005年   101篇
  2004年   82篇
  2003年   93篇
  2002年   77篇
  2001年   20篇
  2000年   37篇
  1999年   42篇
  1998年   21篇
  1997年   22篇
  1996年   24篇
  1995年   21篇
  1994年   18篇
  1993年   15篇
  1992年   17篇
  1991年   18篇
  1990年   20篇
  1989年   22篇
  1988年   24篇
  1987年   12篇
  1986年   16篇
  1985年   13篇
  1984年   11篇
  1983年   9篇
  1980年   12篇
  1979年   17篇
  1978年   10篇
  1976年   10篇
  1975年   9篇
  1974年   9篇
  1973年   11篇
  1972年   8篇
  1971年   12篇
  1970年   14篇
排序方式: 共有1719条查询结果,搜索用时 46 毫秒
141.

Background

Previous studies have suggested a link between metabolic syndrome (MetS) and prostate cancer (PCa). In the present study, we aimed to assess the association between MetS and markers of PCa aggressiveness on radical prostatectomy (RP).

Methods

All patients consecutively treated for PCa by RP in 6 academic institutions between August 2013 and July 2016 were included. MetS was defined as at least 3 of 5 components (obesity, elevated blood pressure, diabetes, low high-density lipoprotein (HDL)-cholesterol, and hypertriglyceridemia). Demographic, biological, and clinical parameters were prospectively collected, including: age, biopsy results, preoperative serum prostate-specific antigen, surgical procedure, and pathological data of RP specimen. Locally advanced disease was defined as a pT-stage ≥3. International Society of Urological Pathology (ISUP) groups were used for pathological grading. Qualitative and quantitative variables were compared using chi-square and Wilcoxon tests; logistic regression analyses assessed the association of MetS and its components with pathological data. Statistical significance was defined as a P<0.05.

Results

Among 567 men, 249 (44%) had MetS. In a multivariate model including preoperative prostate-specific antigen, biopsy ISUP-score, clinical T-stage, age, and ethnicity: we found that MetS was an independent risk factor for positive margins, and ISUP group ≥4 on the RP specimen (odds ratio [OR] = 1.5; 95% CI: 1.1–2.3; P = 0.035; OR = 2.0; 95% CI: 1.1–4.0; P = 0.044, respectively). In addition, low HDL-cholesterol level was associated with locally advanced PCa (OR = 1.6; 95% CI: 1.1–2.4; P = 0.024). Risks of adverse pathological features increased with the number of MetS components: having ≥ 4 MetS components was significantly associated with higher risk of ISUP group ≥ 4 and higher risk of positive margins (OR = 1.9; 95% CI: 1.1–3.3; P = 0.017; OR = 1.8; 95% CI: 1.1–2.8; P = 0.007, respectively).

Conclusion

MetS was an independent predictive factor for higher ISUP group and positive margins at RP. Low HDL-cholesterol alone, and having 4 and more MetS components were also associated with higher risk of adverse pathological features.  相似文献   
142.
OBJECTIVES: To measure the in vitro post-antibiotic effect (PAE) and post-beta-lactamase inhibitor effect (PLIE) of a ceftazidime-sulbactam combination on bacteria producing extended-spectrum beta-lactamases (ESBLs). METHODS: PAE and PLIE were studied for ESBL-producing strains of Escherichia coli and Klebsiella pneumoniae. Two ATCC beta-lactamase-negative strains of E. coli and K. pneumoniae were used as controls. The MICs of a ceftazidime-sulbactam combination were determined with a fixed concentration of sulbactam (8 mg/L). The organisms were exposed to the antibiotics at twice the MIC for 2 h before removal of the antibiotics by filtration of the culture. Bacteria on the filter were resuspended in drug-free medium to determine the PAE and in medium containing ceftazidime, at the same concentration as originally present, to determine the PLIE. RESULTS: The PAE of ceftazidime was similar for bacteria producing the same ESBL except for E. coli producing CTX-M-1. PLIE values varied according to the type of beta-lactamase but similar results were observed for the strains producing the same ESBLs. PLIEs were longer than PAEs and were longer when the MICs of ceftazidime were lower. CONCLUSIONS: To the best of our knowledge, we describe here for the first time an in vitro PLIE for a ceftazidime-sulbactam combination on different bacteria producing different ESBLs. These findings indicate that suicide inhibitors may be used in combination with third-generation cephalosporins.  相似文献   
143.
OBJECTIVE: Plasma ammonia measurement is greatly influenced by pre-analytical conditions, which may lead to false positives. We wanted to evaluate the prevalence and clinical impact of plasma ammonia false positives in a pediatric population. DESIGN AND METHODS: Over a 28-month period, charts of patients with elevated ammonemia were retrospectively reviewed to identify false positives defined as elevated concentrations that subsequently normalized without plausible explanation for the elevations. RESULTS: 1880 Ammonia measurements were available in 479 patients. Elevated results that subsequently normalized were found in 86 patients. Forty-one (48%) of these patients had most likely falsely elevated ammonemia. Additional blood sampling and laboratory testing were the most frequent consequences of false positives. CONCLUSION: There is a high proportion of false positives among elevated plasma ammonia measurements. Capillary samples and delay between sampling and centrifugation are possible contributing factors. Clinical consequences of false positives were most often limited.  相似文献   
144.
145.
In recent years, some concepts regarding the etiology and hemodynamics present in the syndrome of mitral regurgitation have changed. Coronary artery disease and mitral valve prolapse have replaced rheumatic heart disease as the most frequent cause of mitral regurgitation. Hemodynamic studies have shown that tall V waves in the pulmonary capillary wedge tracings are neither specific nor sensitive in detecting the presence of mitral regurgitation. In this study, we evaluated the role of various clinical, echocardiographic, and hemodynamic findings with regard to left atrial (LA) size, pressure, and V wave height. We found that the mean pulmonary capillary wedge pressure (PCW) and V wave height for the subset of patients with acute mitral regurgitation (PCW = 24.1 ± 10.9; V = 41.2 ± 20.7 mm Hg) was similar to the subset with chronic mitral regurgitation (PCW = 17.9 ± 7.5; V = 32.0 ± 18.2 mm Hg). In addition, we found that there was a significant logarithmic relationship between the LA size and the duration of the mitral regurgitation (y = 1.404 [log X] + 3.948; R = 0.678; p < 0.0005). Lastly, we found that LA size, compliance, regurgitant volume, and regurgitant valve orifice area all increase with time.  相似文献   
146.
Malformations of the hippocampal formation and amygdala have been implicated in several neurodevelopmental disorders; yet relatively little is known about their normal structural development. The purpose of this study was to characterize the early developmental trajectories of the hippocampus and amygdala in the rhesus macaques (Macaca mulatta) using noninvasive MRI techniques. T1‐weighted structural scans of 22 infant and juvenile monkeys (11 male, 11 female) were obtained between 1 week and approximately 2 yrs of age. Ten animals (five males, five females) were scanned multiple times and 12 monkeys (six males, six females) were scanned once between 1 and 4 weeks of age. Both structures exhibited significant age‐related changes throughout the first 2 yrs of life that were not explained by overall brain development. The hippocampal formation increased 117.05% in males and 110.86% in females. No sex differences were evident, but the left hemisphere was significantly larger than the right. The amygdala increased 86.49% in males and 72.94% in females with males exhibiting a larger right than left amygdala. For both structures, the most substantial volumetric increases were seen within the first month, but the hippocampal formation appeared to develop more slowly than the amygdala with the rate of hippocampal maturation stabilizing around 11 months and that of amygdala maturation stabilizing around 8 months. Differences in volumetric developmental trajectories of the hippocampal formation and amygdala largely mirror differences in the timing of the functional development of these structures. The current results emphasize the importance of including early postnatal ages when assessing developmental trajectories of neuroanatomical structures and reinforces the utility of nonhuman primates in the assessment of normal developmental patterns. © 2009 Wiley‐Liss, Inc.  相似文献   
147.
Several studies suggest that the biological responses induced by manufactured nanoparticles (MNPs) may be linked to their accumulation within cells. However, MNP internalisation has not yet been sufficiently characterised. Therefore, the aim of this study was to compare the intracellular uptake of three different MNPs: two made of carbon black (CB) and one made of titanium dioxide (TiO(2)), in 16HBE bronchial epithelial cells and MRC5 fibroblasts. Transmission electron microscopy was used to evaluate the intracellular accumulation. Different parameters were analysed following a time and dose-relationship: localisation of MNPs in cells, percentage of cells having accumulated MNPs, number of aggregated MNPs in cells, and the size of MNP aggregates in cells. The results showed that MNPs were widely and rapidly accumulated in 16HBE cells and MRC5 fibroblasts. Moreover, MNPs accumulated chiefly as aggregates in cytosolic vesicles and were absent from the mitochondria or nuclei. CB and TiO(2) MNPs had similar accumulation patterns. However, TiO(2) aggregates had a higher size than CB aggregates. Intracellular MNP accumulation was dissociated from cytotoxicity. These results suggest that cellular uptake of MNPs is a common phenomenon occurring in various cell types.  相似文献   
148.
Multi-parametric flow cytometry analysis is a reliable method for phenotypic and functional characterization of tumor infiltrating immune cells (TIIC). The isolation of infiltrating leukocytes from solid tumors can be achieved through various methods which can be both enzymatic and mechanical; however, these methods may alter cell biology. The aim of this study was to compare the effects of three tissue disaggregation techniques on TIIC biology in breast, kidney and lung tumor specimens. We therefore compared two enzymatic treatments using either collagenase type IA alone or in combination with collagenase type IV and DNase I type II, and one mechanical system (Medimachine?). We evaluated the impact of treatments on cell viability, surface marker integrity and proliferative capacity. We show that cell viability was not significantly altered by treatments. However, enzymatic treatments decreased cell proliferation; specifically collagenases and DNase provoked a significant decrease in detection of surface markers such as CD4, CD8, CD45RA and CD14, indicating that results of phenotypic studies employing these techniques could be affected. In conclusion, mechanical tissue disaggregation by Medimachine? appears to be optimal to maintain phenotypic and functional TIIC features.  相似文献   
149.
Perilipin is the most abundant adipocyte-specific protein that coats lipid droplets, and it is required for optimal lipid incorporation and release from the droplet. We identified two heterozygous frameshift mutations in the perilipin gene (PLIN1) in three families with partial lipodystrophy, severe dyslipidemia, and insulin-resistant diabetes. Subcutaneous fat from the patients was characterized by smaller-than-normal adipocytes, macrophage infiltration, and fibrosis. In contrast to wild-type perilipin, mutant forms of the protein failed to increase triglyceride accumulation when expressed heterologously in preadipocytes. These findings define a novel dominant form of inherited lipodystrophy and highlight the serious metabolic consequences of a primary defect in the formation of lipid droplets in adipose tissue.  相似文献   
150.
The objective of this article was developing an automated tool for routine clinical practice to estimate urinary stone composition from CT images based on the density of all constituent voxels. A total of 118 stones for which the composition had been determined by infrared spectroscopy were placed in a helical CT scanner. A standard acquisition, low-dose and high-dose acquisitions were performed. All voxels constituting each stone were automatically selected. A dissimilarity index evaluating variations of density around each voxel was created in order to minimize partial volume effects: stone composition was established on the basis of voxel density of homogeneous zones. Stone composition was determined in 52% of cases. Sensitivities for each compound were: uric acid: 65%, struvite: 19%, cystine: 78%, carbapatite: 33.5%, calcium oxalate dihydrate: 57%, calcium oxalate monohydrate: 66.5%, brushite: 75%. Low-dose acquisition did not lower the performances (P < 0.05). This entirely automated approach eliminates manual intervention on the images by the radiologist while providing identical performances including for low-dose protocols.  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