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   527515篇
  免费   27668篇
  国内免费   478篇
耳鼻咽喉   6684篇
儿科学   16871篇
妇产科学   12530篇
基础医学   92301篇
口腔科学   12345篇
临床医学   47793篇
内科学   94483篇
皮肤病学   11855篇
神经病学   34076篇
特种医学   19783篇
外国民族医学   53篇
外科学   77942篇
综合类   7601篇
一般理论   107篇
预防医学   38304篇
眼科学   11831篇
药学   41513篇
  1篇
中国医学   1076篇
肿瘤学   28512篇
  2018年   5648篇
  2017年   4103篇
  2016年   4851篇
  2015年   5336篇
  2014年   7143篇
  2013年   10560篇
  2012年   15643篇
  2011年   17468篇
  2010年   9980篇
  2009年   8859篇
  2008年   15799篇
  2007年   17546篇
  2006年   17028篇
  2005年   16332篇
  2004年   15950篇
  2003年   15317篇
  2002年   14825篇
  2001年   22448篇
  2000年   22966篇
  1999年   18834篇
  1998年   4993篇
  1997年   4089篇
  1996年   4129篇
  1995年   4115篇
  1992年   14428篇
  1991年   15840篇
  1990年   15972篇
  1989年   15645篇
  1988年   14317篇
  1987年   14204篇
  1986年   13182篇
  1985年   12711篇
  1984年   9402篇
  1983年   8005篇
  1982年   4170篇
  1981年   3802篇
  1979年   8942篇
  1978年   6371篇
  1977年   5138篇
  1976年   5490篇
  1975年   6597篇
  1974年   7403篇
  1973年   7152篇
  1972年   6584篇
  1971年   6303篇
  1970年   5882篇
  1969年   5457篇
  1968年   5158篇
  1967年   4618篇
  1966年   3963篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ObjectiveTo determine prognostic factors and survival patterns for different treatment modalities for nasal cavity (NC) and paranasal sinus (PS) mucosal melanoma (MM).MethodsPatients from 1973 to 2013 were analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier method and multivariable cox proportional hazard modeling were used for survival analyses.ResultsOf 928 cases of mucosal melanoma (NC = 632, PS = 302), increasing age (Hazard Ratio [HR]:1.05/year, p < 0.001), T4 tumors (HR: 1.81, p = 0.02), N1 status (HR: 6.61, p < 0.001), and PS disease (HR: 1.50, p < 0.001) were associated with worse survival. Median survival length was lower for PS versus NC (16 versus 26 months, p < 0.001). Surgery and surgery + radiation therapy (RT) improved survival over non-treatment or RT alone (p < 0.001). Adding RT to surgery did not yield a survival difference compared with surgery alone (p = 0.43). Five-year survival rates for surgery and surgery + RT were similar, at 27.7% and 25.1% (p = 0.43).ConclusionSurgery increased survival significantly over RT alone. RT following surgical resection did not improve survival.  相似文献   
2.
3.
Neuroscience and Behavioral Physiology - We present here results from analysis of the formation of brain bioelectrical activity in children and adolescents living in the northern region of Russia...  相似文献   
4.
5.
6.
7.
8.
9.
BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a highly transmissible pathogenic coronavirus emerged in late 2019 causing a pandemic of acute respiratory disease, named ‘coronavirus disease 2019’ (COVID-19). It has spread fast all over the world posing an extraordinary threat to global public health. Along with SARS-CoV-2, there are seven human coronaviruses. Those causing mild diseases are the 229E, OC43, NL63 and HKU1, and the pathogenic ones are SARSCoV, MERS-CoV and SARS-CoV-2.ObjectiveThis review has highlighted the basic virology of SARS CoV-2 including its origin, structure, genomic characteristics, pathogenesis, immunological response and clinical manifestation along with the key difference of SARS CoV2 from the previous Coronaviruses.ContentCoronaviruses are spherical and enveloped with club-shaped spikes on the surface. It has a large positive sense, single stranded RNA genome within the nucleocapsid with a helical symmetry. It has been known to cause infection to innumerable mammalian hosts, like humans, cats, bats, civets, dogs, and camels. The viral genome contains four major structural proteins: the spike (S), membrane (M), envelope (E) and the nucleocapsid (N) protein encoded within the 3’ end of the genome. Virus binds to the host cell by the S protein with specific receptor. Following receptor binding, the virus enters host cell cytosol and there is fusion of the viral and cellular membranes followed by the translation of the viral genomic RNA. Following the viral replication and sub-genomic RNA synthesis, there is formation of the mature virus. The virions are then transported to the cell surface in vesicles and are released by exocytosis.  相似文献   
10.
Microbial co-infections are another primary concern in patients with coronavirus disease 2019 (COVID-19), yet it is an untouched area among researchers. Preliminary data and systematic reviews only show the type of pathogens responsible for that, but its pathophysiology is still unknown. Studies show that these microbial co-infections are hospital-acquired/nosocomial infections, and patients admitted to intensive care units with invasive mechanical ventilation are highly susceptible to it. Patients with COVID-19 had elevated inflammatory cytokines and a weakened cell-mediated immune response, with lower CD4+ T and CD8+ T cell counts, indicating vulnerability to various co-infections. Despite this, there are only a few studies that recommend the management of co-infections.  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