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   2364篇
  免费   139篇
耳鼻咽喉   20篇
儿科学   108篇
妇产科学   61篇
基础医学   252篇
口腔科学   18篇
临床医学   299篇
内科学   488篇
皮肤病学   21篇
神经病学   238篇
特种医学   58篇
外科学   291篇
综合类   22篇
预防医学   246篇
眼科学   69篇
药学   168篇
肿瘤学   144篇
  2023年   21篇
  2022年   30篇
  2021年   56篇
  2020年   46篇
  2019年   68篇
  2018年   77篇
  2017年   50篇
  2016年   46篇
  2015年   53篇
  2014年   94篇
  2013年   109篇
  2012年   155篇
  2011年   200篇
  2010年   103篇
  2009年   88篇
  2008年   148篇
  2007年   167篇
  2006年   158篇
  2005年   153篇
  2004年   125篇
  2003年   125篇
  2002年   133篇
  2001年   27篇
  2000年   23篇
  1999年   19篇
  1998年   24篇
  1997年   21篇
  1996年   15篇
  1995年   12篇
  1994年   6篇
  1993年   7篇
  1992年   12篇
  1991年   7篇
  1990年   5篇
  1989年   8篇
  1988年   9篇
  1987年   8篇
  1986年   4篇
  1985年   5篇
  1984年   8篇
  1983年   6篇
  1982年   7篇
  1981年   5篇
  1980年   9篇
  1977年   5篇
  1976年   4篇
  1974年   7篇
  1972年   4篇
  1971年   4篇
  1966年   5篇
排序方式: 共有2503条查询结果,搜索用时 15 毫秒
31.
The number of individuals diagnosed with colorectal cancer (CRC) has been on an alarming upward trajectory over the past decade. In some countries, this cancer represents one of the most frequently diagnosed types of neoplasia. Therefore, it is an important demand to study the pathology underlying this disease to gain insights into the mechanism of resistance to treatment. Resistance of tumors to chemotherapy and tumor aggressiveness have been associated with a minor population of neoplastic cells, which are considered to be responsible for tumor recurrence. These types of neoplastic cells are known as cancer stem cells, which have been previously reported to serve an important role in pathogenesis of this malignant disease. Slovakia has one of the highest incidence rates of CRC worldwide. In the present study, the aim was to classify the abundance of selected stem cell markers (CD133, CD166 and Lgr5) in CRC tumors using flow cytometry. In addition, the methylation status of selected genomic regions of CRC biomarkers (ADAMTS16, MGMT, PROM1 (CD133), LGR5 and ALCAM) was investigated by pyrosequencing in a cohort of patients from Martin University Hospital, Martin, Slovakia. Samples from both primary tumors and metastatic tumors were tested. Analysis of DNA methylation in the genomic regions of indicated five CRC biomarkers was also performed, which revealed the highest levels of methylation in the A disintegrin and metalloproteinase with thrombospondin motifs 16 and O6-methyguanine-DNA methyl transferase genes, whereas the lowest levels of methylation were found in genes expressing prominin-1, leucine-rich repeat-containing G-protein-coupled receptor 5 and activated leukocyte cell adhesion molecule. Furthermore, tumor tissues from metastases showed significantly higher levels of CD133+ cells compared with that in primary tumors. Higher levels of CD133+ cells correlated with TNM stage and the invasiveness of CRC into the lymphatic system. Although relatively small number of samples was processed, CD133 marker was consider to be important marker in pathology of CRC.  相似文献   
32.
One of the major objectives of food industry is to develop low-cost biodegradable food packaging films with optimal physicochemical properties, allowing for their large-scale production and providing a variety of applications. To meet the expectations of food industry, we have fabricated a series of solution-cast films based on common biodegradable polysaccharides (starch, chitosan and alginate) to be used in food packaging applications. Selected biopolymers were modified by the addition of glycerol and oxidized sucrose (starch), glycerol (chitosan), and glycerol and calcium chloride (alginate), as well as being used to form blends (starch/chitosan and starch/alginate, respectively). A chestnut extract was used to provide antibacterial properties to the preformed materials. The results of our studies showed that each modification reduced the hydrophilic nature of the polymers, making them more suitable for food packaging applications. In addition, all films exhibited much higher barrier properties to oxygen and carbon dioxide than commercially available films, such as polylactic acid, as well as exhibiting antimicrobial properties against model Gram-negative and Gram-positive bacteria (Escherichia coli and Staphylococcus epidermidis, respectively), as well as yeast (Candida albicans).  相似文献   
33.
34.
35.
36.
This study examined the transition from most-to-least possible restrictive environments for youth with emotional and behavioral disorders. Components of positive transition experiences were identified from the literature as planning for transition at intake in such a way as to promote continuity of care, family involvement, academic and employment success, and assistance in navigating the adult mental health system and services. In this phenomenological study, transition service providers were interviewed to explore the transition practices currently utilized, and results were compared to recommended practices in the literature. Transition professionals were able to identify consistency, gradual change, individualization, communication between providers, opportunities for community experiences, and youth involvement in the transition as necessary to successful transition.  相似文献   
37.
38.
There is conflicting clinical evidence whether administration of coenzyme Q10 (CoQ10) improves function following coronary artery bypass graft surgery (CABG). Using a swine model of hibernating myocardium, we tested whether daily CoQ10 would improve contractile function by MRI at 4-week post-CABG. Twelve pigs underwent a thoracotomy and had a constrictor placed on the left anterior descending (LAD). At 12 weeks, they underwent off-pump bypass and received daily dietary supplements of either CoQ10 (10 mg/kg/day) or placebo. At 4-week post-CABG, circumferential strain measurements in the hibernating LAD region from placebo and CoQ10 groups were not different and increased to a similar extent with dobutamine (?14.7?±?0.6 versus ?14.8?±?0.1, respectively (NS)). Post-sacrifice, oxidant stress markers were obtained in the mitochondrial isolates and protein carbonyl in the placebo, and CoQ10 groups were 6.14?±?0.36 and 5.05?±?0.32 nmol/mg, respectively (NS). In summary, CoQ10 did not improve contractile reserve or reduce oxidant stress at 4-week post-CABG.  相似文献   
39.
The aim of this experimental work was to evaluate deposition of titanium dioxide (TiO2) microparticles and nanoparticles, which could originate from titanium bioimplants, in the gingiva. Wistar rats were injected intraperitoneally (i.p.) with a suspension of TiO2 particles of different sizes (150, 10, or 5 nm). The rats were killed 12 months post‐injection, and the buccal and lingual gingivae were resected and evaluated using light and scanning electron microscopy. Energy‐dispersive X‐ray spectroscopy (EDS) was used to confirm the presence of titanium in deposits of microparticles and nanoparticles, and the concentration of titanium in tissues was measured using inductively coupled plasma–mass spectrometry (ICP‐MS). Histological examination showed that all experimental groups exhibited agglomerates, in the gingiva, of titanium particles of micrometer size range, with no associated inflammatory response. Higher concentrations of titanium traces were shown, by ICP‐MS, in both buccal and lingual tissues of all experimental groups compared with their matched controls. Titanium concentrations were significantly higher in the buccal gingiva than in the lingual gingiva, and after injection with 5‐nm particles than with 10‐nm particles in both localizations. Titanium microparticles and nanoparticles deposit in the gingiva, and mostly on the buccal side. Gingival deposition of titanium could be considered a tissue indicator of tribocorrosion processes of titanium bioimplants.  相似文献   
40.
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