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   387篇
  免费   11篇
儿科学   6篇
妇产科学   2篇
基础医学   48篇
口腔科学   1篇
临床医学   37篇
内科学   59篇
皮肤病学   32篇
神经病学   8篇
特种医学   21篇
外科学   37篇
综合类   2篇
预防医学   119篇
眼科学   3篇
药学   18篇
中国医学   1篇
肿瘤学   4篇
  2023年   2篇
  2022年   7篇
  2021年   5篇
  2020年   6篇
  2019年   6篇
  2018年   11篇
  2017年   5篇
  2016年   10篇
  2015年   6篇
  2014年   5篇
  2013年   13篇
  2012年   34篇
  2011年   37篇
  2010年   22篇
  2009年   21篇
  2008年   20篇
  2007年   25篇
  2006年   25篇
  2005年   21篇
  2004年   24篇
  2003年   19篇
  2002年   19篇
  2001年   7篇
  2000年   5篇
  1999年   3篇
  1997年   1篇
  1995年   1篇
  1994年   3篇
  1992年   2篇
  1991年   3篇
  1990年   9篇
  1989年   6篇
  1988年   4篇
  1987年   4篇
  1986年   2篇
  1984年   2篇
  1983年   1篇
  1979年   1篇
  1969年   1篇
排序方式: 共有398条查询结果,搜索用时 15 毫秒
391.
OBJECTIVES: The study was aimed to evaluate osteoporosis prevalence in a group of Tunisian patients with inflammatory bowel disease (IBD), to determine its risk factors, and to describe its mechanisms. SUBJECTS AND METHODS: We included 67 IBD patients, 43 patients with Crohn's disease (CD) and 24 with ulcerative colitis (UC). Bone mineral density was measured at the lumbar spine and left femoral neck by dual-energy X-ray absorptiometry. We used T score to express bone loss (osteopenia: -2.5 SD 2 years and active disease tended to be associated with lumbar osteoporosis; the ORs were respectively 4.87 [0.92-25.80] (P=0.06), 4.21 [0.87-20.57] (P=0.06), and 2.33 [0.78-6.67] (P=0.13). No association was found with cumulated dose of steroids even when considering only CD. Patients with osteoporosis showed significant increased CrossLaps and interleukin-6 levels that indicate both high bone resorption and inflammatory activity. CONCLUSIONS: Osteoporosis is frequent in IBD patients, especially in CD patients. Female gender, malnutrition (body mass index <20 kg/m2), disease course (> 2 years) and active disease would be risk factors of bone mineral loss in IBD. Osteoporosis is associated with enhanced bone resorption, that seems be linked to excessive intestinal inflammation.  相似文献   
392.
393.
394.
395.
396.
INTRODUCTION: The occurrence of skin damage during systemic amyloidosis is common, but the appearance of bullous lesions is rare. Only twenty-seven cases have been reported in the literature. We report our observation of bullous amyloidosis during progression of renal amyloidosis. OBSERVATION: A 61 year-old man, presented with white, soft, palpebral edemas of the lower limbs, without scutulum involvement, associated with a large cubital nerve that had appeared in March 1997. Biological explorations revealed a nephrotic syndrome. Pathologic study of the renal biopsy concluded in amyloidosis. Treatment with colchinine stabilized the renal damage. One year later, a non-pruriginous, papular and bullous eruption occurred, localized essentially in the axillary and inguinal-crural folds of the forearms and legs. In the presence of an amyloidal deposit and intra-epidermal detachment, the cutaneous biopsy was evocative of bullous amyloidosis. The search for concomitant myeloma was negative. Treatment with colchinine was effective. The bullous lesions disappeared after 2 months, and 21 months later, renal damage was still stable. DISCUSSION: These particularities in evolution are exceptional and have never been described. A hypothetical modification in the physico-chemical properties of the amyloidal protein might explain the bullous eruption and stabilization of renal damage.  相似文献   
397.
Four magnetite nanoparticle (NP) samples have been greenly synthesized using four aqueous plant extracts, which are Artemisia herba-alba (L), Rosmarinus officinalis (L), Matricaria pubescens (L), and Juniperus phoenicia (L). The pH of these extracts are acidic (5.25, 5.05, 4.63, and 3.69, respectively). The synthesized samples were characterized by XRD, SEM, ATR-FTIR, and UV-Vis. This work aimed to study the preferential and enhanced adsorption of methyl green (MG) on the four greenly synthesized Fe3O4 surfaces by coupling three processes: MG adsorption in ambient dark conditions as the first process, followed by the thermocatalysis of the MG/Fe3O4 residual solution in the second process, and finally photocatalysis by the UV irradiation of MG/Fe3O4 residual solution after carrying out thermocatalysis. The novelty of this study lies in highlighting the influence of the mediating plant extract’s acidity on the magnetite NPs’ physicochemical characteristics, which impact the preferential and enhanced MG adsorption. The studied physicochemical characteristics are the functional hydroxyl group density on the magnetite surface, grain size, and band gap energy. It was found that the plant extract’s acidity has a clear effect on the studied physicochemical properties. The analysis of the FTIR spectra showed that the hydroxyl group densities differ on the four magnetite samples. Furthermore, the calculated grain sizes of the magnetite samples based on XRD spectra data vary from 29.27 to 41.49 nm. The analysis of the UV-Vis spectra of the four magnetite samples showed that the estimated direct band gap energies vary from 2.87 to 2.97 eV. The obtained results showed that the decrease of the mediating plant extract’s acidity leads to an increase in the hydroxyl group density on magnetite surfaces, which resulted in an increase in the MG adsorption capacities and yields in the first process of adsorption. Thus, MG adsorption was more preferred on greenly synthesized magnetite surfaces mediated by plant extracts with low acidity (Artemisia herba-alba (L) and Rosmarinus officinalis (L)). Furthermore, the increase of the plant extract’s acidity leads to a decrease in the particle size and an increase in the band gap energy and, therefore, to the decrease of the electron/hole pair recombination speed upon electron excitation. So, magnetite greenly synthesized from a more acidic mediating plant extract showed higher thermo- and photocatalytic activities for MG adsorption (Juniperus phoenicia (L) and Matricaria pubescens (L)). However, under photocatalysis, the enhancement is even more significant compared to thermocatalysis.

Magnetite NP samples synthesized from less acidic plant extracts have more dense active sites and prefer adsorbing more MG. The increase of plant extract acidity leads to the increase of the thermo- and photocatalytic activities of Fe3O4 NPs.  相似文献   
398.
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