首页 | 官方网站   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   3004062篇
  免费   263057篇
  国内免费   13254篇
医药卫生   3280373篇
  2021年   54660篇
  2020年   35023篇
  2019年   57902篇
  2018年   70349篇
  2017年   53224篇
  2016年   58601篇
  2015年   73116篇
  2014年   107230篇
  2013年   172194篇
  2012年   80505篇
  2011年   78792篇
  2010年   113740篇
  2009年   118721篇
  2008年   66035篇
  2007年   67649篇
  2006年   78964篇
  2005年   74176篇
  2004年   76495篇
  2003年   67509篇
  2002年   57606篇
  2001年   85213篇
  2000年   77169篇
  1999年   80610篇
  1998年   63063篇
  1997年   61296篇
  1996年   59002篇
  1995年   54534篇
  1994年   48709篇
  1993年   45489篇
  1992年   54380篇
  1991年   52182篇
  1990年   49100篇
  1989年   49246篇
  1988年   45441篇
  1987年   44274篇
  1986年   42082篇
  1985年   42653篇
  1984年   40771篇
  1983年   37768篇
  1982年   38473篇
  1981年   36535篇
  1980年   34500篇
  1979年   32514篇
  1978年   30463篇
  1977年   28188篇
  1976年   25910篇
  1975年   24583篇
  1974年   24425篇
  1973年   23336篇
  1972年   21909篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
991.
992.
Phone use is a critical communication event in many people''s lives. Audiologists have aimed to assist individuals with hearing loss and phone usage through the use of technology and counseling. To counsel effectively, all contributions to hearing difficulty on the phone must be considered, including the effects of smartphone cases. The purpose of this study was to evaluate the effects on dB output caused by waterproof smartphone cases that cover the ear-level speaker. One waterproof case was tested with three smartphones, two iPhones, and one Android. A second waterproof case was tested with the two iPhones. Results revealed there was significant attenuation of the audio-signal by both waterproof smartphone cases that was great enough in one case/phone combination to potentially result in a complete lack of intelligibility of the signal.  相似文献   
993.
994.
995.
In this review we summarize the impact of the various modalities of breast cancer therapy coupled with intrinsic patient factors on incidence of subsequent treatment-induced myelodysplasia and acute myelogenous leukemia (t-MDS/AML). It is clear that risk is increased for patients treated with radiation and chemotherapy at younger ages. Radiation is associated with modest risk, whereas chemotherapy, particularly the combination of an alkylating agent and an anthracycline, carries higher risk and radiation and chemotherapy combined increase the risk markedly. Recently, treatment with granulocyte colony-stimulating factor (G-CSF), but not pegylated G-CSF, has been identified as a factor associated with increased t-MDS/AML risk. Two newly identified associations may link homologous DNA repair gene deficiency and poly (ADP-ribose) polymerase inhibitor treatment to increased t-MDS/AML risk. When predisposing factors, such as young age, are combined with an increasing number of potentially leukemogenic treatments that may not confer large risk singly, the risk of t-MDS/AML appears to increase. Patient and treatment factors combine to form a biological cascade that can trigger a myelodysplastic event. Patients with breast cancer are often exposed to many of these risk factors in the course of their treatment, and triple-negative patients, who are often younger and/or BRCA positive, are often exposed to all of them. It is important going forward to identify effective therapies without these adverse associated effects and choose existing therapies that minimize the risk of t-MDS/AML without sacrificing therapeutic gain.

Implications for Practice

Breast cancer is far more curable than in the past but requires multimodality treatment. Great care must be taken to use the least leukemogenic treatment programs that do not sacrifice efficacy. Elimination of radiation and anthracycline/alkylating agent regimens will be helpful where possible, particularly in younger patients and possibly those with homologous repair deficiency (HRD). Use of colony-stimulating factors should be limited to those who truly require them for safe chemotherapy administration. Further study of a possible leukemogenic association with HRD and the various forms of colony-stimulating factors is badly needed.
  相似文献   
996.
目的:建立鼠巨细胞病毒(MCMV)感染C57BL/6小鼠急性肝炎模型并对其感染特点进行分析及鉴定。方法:将24 只C57BL/6小鼠随机分为阴性对照组(n =12)及病毒感染组(n =12),病毒感染组腹腔注射1.0×106 PFU(200 μL)MCMV悬液,阴性对照组注射等体积小鼠胚胎成纤维细胞(MEF)悬液。于感染后第3天和第7天取外周血分离血清检测谷丙转氨酶(ALT)及谷草转氨酶(AST)。同时进行肝组织病毒分离、组织病理学及MCMV IE和M55基因、细胞因子白细胞介素-6(IL-6)、白细胞介素-1β(IL-1β)、肿瘤坏死因子α(TNF-α)的检测。结果:病毒感染组肝组织匀浆病毒分离均为阳性,肝炎发生率为100%。在感染后第3天即发生肝炎病理改变,病毒感染组血清ALT及AST较阴性对照组明显升高(P <0.01);病毒感染组肝脏HE染色第3天可见局灶性炎性细胞浸润及肝脏点灶状坏死,持续至第7天,Ishak评分较阴性对照组明显升高(P <0.01);在感染后第3天病毒感染组肝组织内可检测到MCMV IE及M55基因,且在感染后第7天仍可测得IE基因;感染后第3天及第7天病毒感染组炎性细胞因子IL-6、TNF-α及IL-1β mRNA表达水平明显升高(P <0.05)。 结论:成功建立MCMV感染C57BL/6小鼠急性动物肝炎模型,其感染表现主要集中在急性感染前期。  相似文献   
997.
998.
999.
1000.
We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa’s environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.  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-23

京公网安备 11010802026262号