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   1763篇
  免费   117篇
  国内免费   14篇
耳鼻咽喉   65篇
儿科学   41篇
妇产科学   69篇
基础医学   178篇
口腔科学   61篇
临床医学   167篇
内科学   306篇
皮肤病学   33篇
神经病学   105篇
特种医学   62篇
外科学   224篇
综合类   43篇
预防医学   139篇
眼科学   65篇
药学   202篇
中国医学   40篇
肿瘤学   94篇
  2024年   4篇
  2023年   29篇
  2022年   79篇
  2021年   98篇
  2020年   73篇
  2019年   86篇
  2018年   96篇
  2017年   79篇
  2016年   67篇
  2015年   68篇
  2014年   85篇
  2013年   92篇
  2012年   145篇
  2011年   125篇
  2010年   71篇
  2009年   55篇
  2008年   109篇
  2007年   71篇
  2006年   82篇
  2005年   58篇
  2004年   44篇
  2003年   46篇
  2002年   44篇
  2001年   20篇
  2000年   16篇
  1999年   17篇
  1998年   12篇
  1997年   9篇
  1996年   4篇
  1995年   3篇
  1994年   3篇
  1992年   7篇
  1991年   5篇
  1990年   13篇
  1989年   10篇
  1988年   10篇
  1987年   10篇
  1986年   5篇
  1985年   8篇
  1984年   8篇
  1983年   3篇
  1982年   3篇
  1981年   5篇
  1978年   3篇
  1977年   4篇
  1976年   2篇
  1975年   3篇
  1973年   1篇
  1969年   2篇
  1928年   1篇
排序方式: 共有1894条查询结果,搜索用时 11 毫秒
41.
Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal. Because of their multifunctional characteristics, e.g., simplistic synthesis, acceptable environmental stability, beneficial optical, electronic, and mechanical features, researchers have largely considered them for diverse applications. Therefore, their capability of catalyzing several electrode reactions has been introduced as one of their significant features. A thin layer of the conducting polymer deposited on the substrate electrode surface can augment the electrode process kinetics of several solution species. Such electrocatalytic procedures with modified conducting polymer electrodes can create beneficial utilization in diverse fields of applied electrochemistry. This review article explores typical recent applications of conductive polymers (2016–2020) as active electrode materials for energy storage applications, electrochemical sensing, and conversion fields such as electrochemical supercapacitors, lithium-ion batteries, fuel cells, and solar cells.

Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal.  相似文献   
42.
One of the most common causes of implant failure is peri-implantitis, which is caused by bacterial biofilm formation on the surfaces of dental implants. Modification of the surface nanotopography has been suggested to affect bacterial adherence to implants. Silver nanoparticles are also known for their antibacterial properties. In this study, titanium alloy implants were surface modified following silver plating, anodisation and sintering techniques to create a combination of silver, titanium dioxide and hydroxyapatite (HA) nanocoatings. Their antibacterial performance was quantitatively assessed by measuring the growth of Streptococcus sanguinis, proportion of live/dead cells and lactate production by the microbes over 24?h. Application of a dual layered silver–HA nanocoating to the surface of implants successfully inhibited bacterial growth in the surrounding media (100% mortality), whereas the formation of bacterial biofilm on the implant surfaces was reduced by 97.5%. Uncoated controls and titanium dioxide nanocoatings showed no antibacterial effect. Both silver and HA nanocoatings were found to be very stable in biological fluids with material loss, as a result of dissolution, to be less than 0.07% for the silver nanocoatings after 24?h in a modified Krebs-Ringer bicarbonate buffer. No dissolution was detected for the HA nanocoatings. Thus, application of a dual layered silver–HA nanocoating to titanium alloy implants creates a surface with antibiofilm properties without compromising the HA biocompatibility required for successful osseointegration and accelerated bone healing.  相似文献   
43.
Neurological Sciences - Spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disorder of alpha motor neurons of spinal cord associated with progressive muscle weakness and...  相似文献   
44.
45.
Staggerer (sg) is an autosomal recessive mutation in mouse that causes severe cerebellar atrophy. In this mutant, the Purkinje cell (PC) number is reduced by about 75% and the remaining Purkinje cells have a reduced dendritic arbor and an ectopic location. Previous analysis of staggerer chimeras has demonstrated that the Purkinje cell phenotypes are all direct consequences of the cell-autonomous action of the staggerer gene. The two major afferents to the Purkinje cell are also affected. Virtually all of the granule cells die by the end of the first postnatal month. This death, however has been shown to be an indirect consequence of mutant gene action. The second major afferent system is from the cells of the inferior olive that projects to the main trunks of the Purkinje cell dendrite via the climbing fiber system. Quantitative studies of cell number in the inferior olive have shown that the number of cells is reduced by about 62% in adult sg/sg mutants. We report here the results of our quantitative analysis of three staggerer chimeras. beta-glucuronidase activity was used as an independent cell marker. Our findings demonstrate that inferior olive cell death in staggerer mutant mice is an indirect effect of staggerer gene action. Thus as for the granule cells, the loss of olivary neurons most likely results from a target related cell death.  相似文献   
46.
47.
Brain Imaging and Behavior - A higher incidence of cognitive impairment (CI) has previously been reported among orchiectomized testicular cancer patients (TCPs), but little is known about the...  相似文献   
48.
49.
The lateral capacity of exterior concrete columns subjected to a blast load is the key factor in the building collapse probability. Due to potentially severe consequences of the collapse, efforts have been made to improve the blast resistance of existing structures. One of the successful approaches is the use of ultra-high-performance-concrete (UHPC) jacketing for retrofitting a building’s columns. The columns on the first floor of a building normally have higher slenderness due to the higher first story. Since an explosion is more likely to take place at the ground level, retrofitting the columns of the lower floors is crucial to improve a building’s blast resistance. Casting a UHPC tube around a circular RC column can increase the moment of inertia of the column and improve the flexural strength. In this study, a retrofitting system consisting of a UHPC layer enclosed by a thin steel jacket is proposed to improve the blast resistance of buildings in service. Most of the previous research is focused on design aspects of blast-resistant columns and retrofitting systems are mostly based on fiber reinforced polymers or steel jackets. A validated FE model is used to investigate the effectiveness of this method. The results showed significant improvement both at the component and building system levels against combined gravity and blast loading.  相似文献   
50.
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