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   1933篇
  免费   122篇
  国内免费   13篇
耳鼻咽喉   12篇
儿科学   58篇
妇产科学   43篇
基础医学   258篇
口腔科学   30篇
临床医学   227篇
内科学   532篇
皮肤病学   35篇
神经病学   196篇
特种医学   60篇
外科学   152篇
综合类   6篇
预防医学   147篇
眼科学   36篇
药学   129篇
肿瘤学   147篇
  2024年   2篇
  2023年   23篇
  2022年   43篇
  2021年   78篇
  2020年   56篇
  2019年   65篇
  2018年   62篇
  2017年   56篇
  2016年   56篇
  2015年   70篇
  2014年   93篇
  2013年   106篇
  2012年   167篇
  2011年   145篇
  2010年   100篇
  2009年   93篇
  2008年   144篇
  2007年   132篇
  2006年   129篇
  2005年   108篇
  2004年   104篇
  2003年   79篇
  2002年   68篇
  2001年   15篇
  2000年   9篇
  1999年   11篇
  1998年   14篇
  1997年   7篇
  1996年   8篇
  1995年   8篇
  1994年   4篇
  1993年   1篇
  1992年   4篇
  1991年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1978年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有2068条查询结果,搜索用时 15 毫秒
941.

Purpose  

To compare the diagnostic performance of lung ultrasound and bedside chest radiography (CXR) for the detection of various pathologic abnormalities in unselected critically ill patients, using thoracic computed tomography (CT) as a gold standard.  相似文献   
942.
The aim of this study was to assess the effect of ursodeoxycholic acid (UDCA) on the morphological and functional adaptive response of the jejunal remnant after massive intestinal resection in a cat model of short bowel syndrome (SBS). UDCA was administered to animals at a daily oral dose of 15 mg/kg for 6 weeks following a 85% jejunoileal resection. Resection alone caused extensive hyperplasia of jejunal mucosa, as evidenced by a significant increase in the weight of jejunal mucosa per unit length as well as by significant increases in DNA and protein concentration but no change in the protein/DNA ratio. Morphometric analysis using microscopy revealed no changes in jejunal mucosa thickness, jejunal crypt depth, villus height and villus surface area, although villus thickness was increased. The specific activities of jejunal sucrase and alkaline phosphatase were unaffected. UDCA treatment of resected animals, using doses that caused no toxicity, as evidenced by the absence of serum biochemistry abnormalities and histopathology, did not induce, compared to resection alone, any changes in mucosal cellularity and did not affect villus morphometry. On the other hand, UDCA administration increased crypt depth and, also, induced a profound increase in the specific activity of sucrase. UDCA improved diarrhoea, a core SBS symptom, reflected in a considerably reduced frequency of defaecation and improved form and texture of faeces. It is concluded that UDCA administration may enhance the natural adaptive response of the intestinal remnant following massive jejunoileal resection and may, thus, be beneficial in SBS treatment.  相似文献   
943.
The systemic exposure of plum tree growers and operators to plant protection products (PPPs) and effects on DNA were assessed. Specifically, a GC-MS/MS method was developed and validated for the analysis of serum samples for the presence of seven active substances of PPPs. The analytical results verified the presence of myclobutanil, propargite, cypermethrin and deltamethrin in 7 out of 19 serum samples. The incidence of DNA damage was monitored using the single cell electrophoresis assay (comet assay). A paired Student's t-test revealed a statistically significant increase of SSBs in the blood samples collected at the end of the cropping period as compared to the samples collected from the same subjects before the start of PPPs application period. Moreover, the group of seven subjects with detectable serum pesticides levels revealed statistically significant increase of SSBs as compared to the group of subjects with no detectable PPP levels. The results of the present study demonstrate that the agriculture workers may exhibit detectable level of systemic exposure to the applied PPPs which are correlated to increased DNA damage during the cultivation period.  相似文献   
944.
945.
946.
947.
Clusterin, a protein constituent of HDL, was recently shown to bind plasma leptin in vitro and has been proposed to modulate leptin activity. To gain insight into a possible role for plasma clusterin in human obesity, we measured plasma clusterin, leptin, soluble leptin receptor (sObR), and lipoproteins in 70 obese adolescents (12.4 ± 1.6 y; BMI-SD score (SDS-BMI) 2.35 ± 0.47) before and after 3 wk of weight reduction in a dietary camp and in 44 normal weight controls. Binding of plasma leptin to HDL or clusterin was studied using ultracentrifugation and immunoaffinity chromatography. During weight reduction, clusterin decreased from 14.6 ± 4.1 to 10.3 ± 2.9 mg/dL, p < 0.001) in obese adolescents, whereas sObR increased. However, baseline plasma clusterin in obese adolescents did not differ from controls. Clusterin did not correlate with SDS-BMI, weight loss, leptin, or lipoproteins. Only ~ 1% of plasma leptin was associated with clusterin/apoA-I complexes or with HDL. Our results do not support a role for plasma clusterin as an important leptin-binding protein or modulator of leptin action. The decrease of plasma clusterin during weight reduction may be an effect of the hypocaloric diet rather than being directly linked to weight loss.  相似文献   
948.
The aim of the current study was to compare the association of several anthropometric indices, with insulin resistance (IR) proxy measures in European adolescents. The present study comprises 1,097 adolescents aged 12.5-17.5 from ten European cities participating in the HELENA study. Weight, height, waist circumference (WC) and hip circumference, skinfolds thickness, fat mass (FM), fasting plasma glucose (G(F)) and serum insulin (I(F)) levels were measured. HOMA (as indicator of IR body mass index (BMI), waist to hip ratio (WHR) and waist to height ratio (WHtR) were calculated. I(F) and HOMA were statistically significantly related to BMI, WC, skinfold sum, WHtR, WHR and FM. BMI, WC, WHtR, skinfold sum and FM displayed similar correlation with I(F) and HOMA as opposed to WHR where lower correlation with IR indices was detected in the overall sample. Similar results were found for boys, girls and underweight/normal weight adolescents. On the other hand, WC and WHtR were found to be more strongly associated with IR proxy measures compared to the rest of anthropometric indices among overweight/obese subjects. Based on the current findings, WC and WHtR could be used, alternatively, to identify the overweight/obese adolescent at risk for developing IR. In addition, all aforementioned anthropometric indices, except WHR, could be used among the underweight/normal weight adolescents.  相似文献   
949.
950.
BackgroundTo analyze the effect of treatment on neurocognitive functioning and the association of neurocognition with radiological abnormalities in primary central nervous system lymphoma (PCNSL).MethodsOne hundred and ninety-nine patients from a phase III trial (HOVON 105/ALLG NHL 24), randomized to standard chemotherapy with or without rituximab, followed in patients ≤60 years old by 30-Gy whole-brain radiotherapy (WBRT), were asked to participate in a neuropsychological evaluation before and during treatment, and up to 2 years posttreatment. Scores were transformed into a standardized z-score; clinically relevant changes were defined as a change in z-score of ≥1 SD. The effect of WBRT was analyzed in irradiated patients. All MRIs were centrally assessed for white matter abnormalities and cerebral atrophy, and their relation with neurocognitive scores over time in each domain was calculated.Results125/199 patients consented to neurocognitive evaluation. Statistically significant improvements in neurocognition were seen in all domains. A clinically relevant improvement was seen only in the motor speed domain, without differences between the arms. In the follow-up of irradiated patients (n = 43), no change was observed in any domain score, compared to after WBRT. Small but significant inverse correlations were found between neurocognitive scores over time and changes in white matter abnormalities (regression coefficients: −0.048 to −0.347) and cerebral atrophy (−0.212 to −1.774).ConclusionsAddition of rituximab to standard treatment in PCNSL patients did not impact neurocognitive functioning up to 2 years posttreatment, nor did treatment with 30-Gy WBRT in patients ≤60 years old. Increased white matter abnormalities and brain atrophy showed weak associations with neurocognition.  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