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   2714145篇
  免费   208532篇
  国内免费   5997篇
耳鼻咽喉   36141篇
儿科学   90292篇
妇产科学   75611篇
基础医学   384558篇
口腔科学   77587篇
临床医学   246101篇
内科学   531474篇
皮肤病学   62764篇
神经病学   216123篇
特种医学   102961篇
外国民族医学   696篇
外科学   410489篇
综合类   63804篇
现状与发展   7篇
一般理论   948篇
预防医学   207973篇
眼科学   63857篇
药学   196513篇
  7篇
中国医学   6413篇
肿瘤学   154355篇
  2019年   21929篇
  2018年   31475篇
  2017年   23851篇
  2016年   26537篇
  2015年   29925篇
  2014年   41985篇
  2013年   62279篇
  2012年   85376篇
  2011年   90499篇
  2010年   53357篇
  2009年   50303篇
  2008年   83720篇
  2007年   88891篇
  2006年   89743篇
  2005年   86383篇
  2004年   83098篇
  2003年   79096篇
  2002年   76161篇
  2001年   138477篇
  2000年   141871篇
  1999年   117040篇
  1998年   30639篇
  1997年   26710篇
  1996年   26762篇
  1995年   27181篇
  1994年   24872篇
  1993年   23131篇
  1992年   89624篇
  1991年   86101篇
  1990年   82825篇
  1989年   79519篇
  1988年   72761篇
  1987年   71136篇
  1986年   66617篇
  1985年   63457篇
  1984年   47338篇
  1983年   39996篇
  1982年   23288篇
  1981年   20698篇
  1979年   41721篇
  1978年   29042篇
  1977年   24385篇
  1976年   22954篇
  1975年   23886篇
  1974年   28962篇
  1973年   27935篇
  1972年   26047篇
  1971年   23883篇
  1970年   22515篇
  1969年   20995篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The International Journal of Cardiovascular Imaging - Global longitudinal strain (GLS) has proven to be a powerful prognostic marker in various patient populations, but the prognostic value of...  相似文献   
2.
3.
4.
5.
6.
Previous studies on the immunogenicity of SARS-CoV-2 mRNA vaccines showed a reduced seroconversion in cancer patients. The aim of our study is to evaluate the immunogenicity of two doses of mRNA vaccines in solid cancer patients with or without a previous exposure to the virus. This is a single-institution, prospective, nonrandomized study. Patients in active treatment and a control cohort of healthy people received two doses of BNT162b2 (Comirnaty, BioNTech/Pfizer, The United States) or mRNA-1273 (Spikevax, Moderna). Vaccine was administered before starting anticancer therapy or on the first day of the treatment cycle. SARS-CoV-2 antibody levels against S1, RBD (to evaluate vaccine response) and N proteins (to evaluate previous infection) were measured in plasma before the first dose and 30 days after the second one. From January to June 2021, 195 consecutive cancer patients and 20 healthy controls were enrolled. Thirty-one cancer patients had a previous exposure to SARS-CoV-2. Cancer patients previously exposed to the virus had significantly higher median levels of anti-S1 and anti-RBD IgG, compared to healthy controls (P = .0349) and to cancer patients without a previous infection (P < .001). Vaccine type (anti-S1: P < .0001; anti-RBD: P = .0045), comorbidities (anti-S1: P = .0274; anti-RBD: P = .0048) and the use of G-CSF (anti-S1: P = .0151) negatively affected the antibody response. Conversely, previous exposure to SARS-CoV-2 significantly enhanced the response to vaccination (anti-S1: P < .0001; anti-RBD: P = .0026). Vaccine immunogenicity in cancer patients with a previous exposure to SARS-CoV-2 seems comparable to that of healthy subjects. On the other hand, clinical variables of immune frailty negatively affect humoral immune response to vaccination.  相似文献   
7.
8.
The Earth’s mean surface temperature is already approximately 1.1°C higher than pre-industrial levels. Exceeding a mean 1.5°C rise by 2050 will make global adaptation to the consequences of climate change less possible. To protect public health, anaesthesia providers need to reduce the contribution their practice makes to global warming. We convened a Working Group of 45 anaesthesia providers with a recognised interest in sustainability, and used a three-stage modified Delphi consensus process to agree on principles of environmentally sustainable anaesthesia that are achievable worldwide. The Working Group agreed on the following three important underlying statements: patient safety should not be compromised by sustainable anaesthetic practices; high-, middle- and low-income countries should support each other appropriately in delivering sustainable healthcare (including anaesthesia); and healthcare systems should be mandated to reduce their contribution to global warming. We set out seven fundamental principles to guide anaesthesia providers in the move to environmentally sustainable practice, including: choice of medications and equipment; minimising waste and overuse of resources; and addressing environmental sustainability in anaesthetists’ education, research, quality improvement and local healthcare leadership activities. These changes are achievable with minimal material resource and financial investment, and should undergo re-evaluation and updates as better evidence is published. This paper discusses each principle individually, and directs readers towards further important references.  相似文献   
9.
Objective: Hepatocellular carcinoma (HCC) microenvironment has been recognized as a key contributor for cancer progression, metastasis, and drug resistance. The crosstalk between tumor cells, the vascular endothelial growth factor (VEGF), and the chemokine (C-C motif) ligand 2 (CCL2) signaling networks mediates immunoinhibitory impact and facilitates tumor angiogenesis. The current investigation aimed at exploring the potent anti-cancer activity of the newly designed nano-based anti-cancer therapy comprising anti-VEGF drug, avastin (AV), and CCR2 antagonist (CR) to counteract HCC and tracking its mode of action in vivo. Methods: The prepared AV, CR, and AVCR nanoprototypes were characterized by nanoscale characterization techniques in our previous work. Here, they are applied for unearthing their anti-cancer properties / mechanisms in hepatic cancer-induced rats via analyzing protein levels and genetic expression of the elements incorporated in the angiogenesis, apoptosis, and metastasis signalling pathways. Results: The present results revealed a significant down-regulation in the angiogenesis, survival and metastasis indices along with up-regulation in the pro-apoptotic mediators upon treatment of hepatic cancer-bearing rats with the novel synthesized nanomaterials when compared with the untreated counterparts. We showed across HCC model that anti-VEGF in combination with CCR2 antagonism therapy leads to sensitization and enhanced tumor response over anti-VEGF or CCR2 antagonism monotherapy, particularly in its nanoscale formulation. Conclusion: The present approach provides new mechanistic insights into the powerful anti-hepatic cancer advantage of the novel nanoprototypes which is correlated with modulating critical signal transduction pathways implicated in tumor microenviroment such as angiogenesis, apoptosis and metastasis. This research work presents a substantial foundation for future studies focused on prohibiting cancer progression and recovery by targeting tumor microenviroment.  相似文献   
10.
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