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   1810篇
  免费   107篇
  国内免费   18篇
耳鼻咽喉   48篇
儿科学   111篇
妇产科学   75篇
基础医学   192篇
口腔科学   54篇
临床医学   165篇
内科学   380篇
皮肤病学   44篇
神经病学   122篇
特种医学   55篇
外科学   265篇
综合类   43篇
预防医学   133篇
眼科学   23篇
药学   64篇
中国医学   9篇
肿瘤学   152篇
  2023年   26篇
  2022年   39篇
  2021年   85篇
  2020年   36篇
  2019年   59篇
  2018年   61篇
  2017年   41篇
  2016年   42篇
  2015年   41篇
  2014年   64篇
  2013年   58篇
  2012年   112篇
  2011年   122篇
  2010年   73篇
  2009年   74篇
  2008年   105篇
  2007年   132篇
  2006年   97篇
  2005年   78篇
  2004年   72篇
  2003年   83篇
  2002年   42篇
  2001年   25篇
  2000年   41篇
  1999年   40篇
  1998年   18篇
  1997年   16篇
  1996年   6篇
  1995年   13篇
  1994年   14篇
  1993年   14篇
  1992年   17篇
  1991年   17篇
  1990年   15篇
  1989年   14篇
  1988年   11篇
  1987年   14篇
  1986年   17篇
  1985年   11篇
  1984年   5篇
  1983年   5篇
  1982年   7篇
  1980年   7篇
  1979年   7篇
  1977年   6篇
  1976年   11篇
  1975年   6篇
  1970年   4篇
  1969年   4篇
  1923年   3篇
排序方式: 共有1935条查询结果,搜索用时 0 毫秒
31.
Protein kinase C delta (PKCδ) is a multifunctional PKC family member and has been implicated in many types of cancers, including liver cancer. Recently, we have reported that PKCδ is secreted from liver cancer cells, and involved in cell proliferation and tumor growth. However, it remains unclear whether the extracellular PKCδ directly regulates cell surface growth factor receptors. Here, we identify epidermal growth factor receptor (EGFR) as a novel interacting protein of the cell surface PKCδ in liver cancer cells. Imaging studies showed that secreted PKCδ interacted with EGFR‐expressing cells in both autocrine and paracrine manners. Biochemical analysis revealed that PKCδ bound to the extracellular domain of EGFR. We further found that a part of the amino acid sequence on the C‐terminal region of PKCδ was similar to the putative EGFR binding site of EGF. In this regard, the point mutant of PKCδ in the binding site lacked the ability to bind to the extracellular domain of EGFR. Upon an extracellular PKCδ‐EGFR association, ERK1/2 activation, downstream of EGFR signaling, was apparently induced in liver cancer cells. This study indicates that extracellular PKCδ behaves as a growth factor and provides a molecular basis for extracellular PKCδ‐targeting therapy for liver cancer.  相似文献   
32.
33.
Approximately 200,000 cases of ambulant pneumonia per year are currently anticipated in Germany. In order to reduce complications and to further minimize lethality a rapid diagnosis as well as efficient and quick therapy are significant factors within the medical treatment and the diagnosis can be achieved promptly with the aid of lung ultrasound. This article illustrates the sonomorphology of pneumonia as well as diffuse parenchymal lung disease and presents recent studies on the topic. Furthermore, lung ultrasound is compared with other diagnostic methods.  相似文献   
34.
35.
36.
人工瓣膜置换术后心内血栓包括人工瓣膜血栓和左心房血栓,是心脏瓣膜置换术后最严重的并发症之一,其中人工瓣膜血栓每年的发生率为0.2%~6%[1]。目前对瓣膜置换术后心内血栓的治疗主要为溶栓疗法及手术治疗。手术风险较大、费用高;溶栓治疗费用低、风险小,但在诸多方面存在着争议。现回顾性分析2010年9月-2014年6月在笔者医院住院的29例人工瓣膜置换术后心内血栓患者予以尿激酶溶栓治疗的临床资料,报告如下。  相似文献   
37.
Metabolic effects of cortisol may be critically modulated by glucocorticoid metabolism in tissues. Specifically, active cortisol is regenerated from inactive cortisone by the enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11-HSD1) in adipose and liver. We examined activity and mRNA levels of 11-HSD1 and tissue cortisol and cortisone levels in sc adipose tissue biopsies from 12 Caucasian (7 males and 5 females) and 19 Pima Indian (10 males and 9 females) nondiabetic subjects aged 28 +/- 7.6 yr (mean +/- SD; range, 18-45). Adipose 11-HSD1 activity and mRNA levels were highly correlated (r = 0.51, P = 0.003). Adipose 11-HSD1 activity was positively related to measures of total (body mass index, percentage body fat) and central (waist circumference) adiposity (P < 0.05 for all) and fasting glucose (r = 0.43, P = 0.02), insulin (r = 0.60, P = 0.0005), and insulin resistance by the homeostasis model (r = 0.70, P < 0.0001) but did not differ between sexes or ethnic groups. Intra-adipose cortisol was positively associated with fasting insulin (r = 0.37, P = 0.04) but was not significantly correlated with 11-HSD1 mRNA or activity or with other metabolic variables. In this cross-sectional study, higher adipose 11-HSD1 activity is associated with features of the metabolic syndrome. Our data support the hypothesis that increased regeneration of cortisol in adipose tissue influences metabolic sequelae of human obesity.  相似文献   
38.
Allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) has been performed as an alternative to bone marrow transplantation (BMT). Here we report poor mobilization with granulocyte-colony stimulating factor (G-CSF) and engraftment kinetics in Allo-PBSCT. Sixteen patients (aged 6-61 yr, median 34 yr) received allogeneic peripheral blood stem cells from related donors (aged 15-68 yr, median 37 yr) after myeloablative therapy. Nine of the patients had standard-risk disease and 7 had high-risk disease. The donors received G-CSF at a dose of 10 micrograms/kg/day by subcutaneous injection for 4 to 6 days. Peripheral blood stem cells were subsequently collected in 1 to 3 aphereses and infused immediately. All patients received G-CSF after transplantation. Fifteen patients underwent Allo-PBSCT and one underwent Allo-PBSCT plus BMT. The mean number of CD34+ cells infused in the 15 Allo-PBSCT patients was 6.32 x 10(6)/kg (range 1.28-14.20). The outcomes were compared with 9 identically treated patients who underwent Allo-BMT. The median times until engraftment for neutrophils > 500/microliter and platelets > 20,000/microliter were 14 (range 10-17) and 15 (range 11-50) days in the Allo-PBSCT group and 17 (range 13-29) and 20 (range 16-160) days in the Allo-BMT group, respectively (p = 0.0177 and p = 0.003). Three donors were considered to have poor mobilization (< 2 x 10(6) CD34+ cells/kg of the recipient); two of them yielded 1.28 and 1.78 x 10(6) CD34+ cells/kg in 3 apheresis procedures. The patients who received cells from these donors showed prompt neutrophil engraftment, but one showed delayed platelet engraftment and another died of grade IV acute GVHD before reaching 20,000 platelets/microliter. An additional bone marrow harvest was necessary from one donor because of poor mobilization(0.17 x 10(6) CD34+ cells/kg). Thus, Allo-PBSCT results in more rapid engraftment. It will be necessary to clarify the minimum CD34+ cell dose for complete engraftment in a larger series of trials.  相似文献   
39.
40.
PurposeCrucial steps have been adopted by health and regulatory authorities around the world to respond to the COVID-19 pandemic. This review aims to highlight these steps by providing an overview of the regulatory approaches adopted during the onset of the pandemic, provide an assessment of observed trends, and offer some reflections and proposals to leverage learnings and opportunities from this current pandemic.MethodsDocuments and informational materials on regulating the development and management of medical products during the COVID-19 pandemic were collected and classified. These materials were sourced from official websites and press releases from health authorities and international bodies from selected markets across the globe, and covered the period between January and July 2020. Additional information to support this study was gathered through a literature review and analysis of related data available from the public domain, and was complemented with the authors' personal experience.FindingsCommunication has been vital in addressing the impact of COVID-19. A total of 1705 documents and informational materials related to health or regulatory response to the COVID-19 pandemic were gathered. Of these, 343 (around 20%) were identified as regulatory agilities. These agile approaches were classified into 3 categories, namely, where health and regulatory authorities had: (1) facilitated product management across the entire lifecycle, notably in expediting medical product use for COVID-19, ensuring the continuity of clinical trials, and addressing supply chain issues; (2) strengthened international cooperation; and (3) addressed regulatory burden with the adoption of electronic and digital tools.ImplicationsWhile many regulatory measures have been introduced temporarily as a response to the COVID-19 crisis, there are opportunities for leveraging an understanding from these approaches in order to collectively achieve more efficient regulatory systems and to mitigate and address the impact of COVID-19 and further future-proof the regulatory environment.  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