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   1342709篇
  免费   114883篇
  国内免费   6450篇
耳鼻咽喉   16782篇
儿科学   43304篇
妇产科学   36704篇
基础医学   184494篇
口腔科学   36422篇
临床医学   121048篇
内科学   278385篇
皮肤病学   31953篇
神经病学   110936篇
特种医学   56017篇
外国民族医学   274篇
外科学   211549篇
综合类   32563篇
现状与发展   2篇
一般理论   439篇
预防医学   106972篇
眼科学   28127篇
药学   94636篇
  33篇
中国医学   2206篇
肿瘤学   71196篇
  2018年   14306篇
  2017年   11175篇
  2016年   13625篇
  2015年   15210篇
  2014年   20884篇
  2013年   30969篇
  2012年   37257篇
  2011年   39446篇
  2010年   25208篇
  2009年   24596篇
  2008年   36869篇
  2007年   39259篇
  2006年   40309篇
  2005年   38848篇
  2004年   36996篇
  2003年   35900篇
  2002年   33855篇
  2001年   66008篇
  2000年   67867篇
  1999年   56378篇
  1998年   16090篇
  1997年   14303篇
  1996年   15280篇
  1995年   16198篇
  1994年   15078篇
  1993年   14123篇
  1992年   47062篇
  1991年   45770篇
  1990年   43988篇
  1989年   41821篇
  1988年   38759篇
  1987年   38078篇
  1986年   35852篇
  1985年   34628篇
  1984年   26352篇
  1983年   22068篇
  1982年   13832篇
  1981年   12412篇
  1980年   11681篇
  1979年   23507篇
  1978年   17022篇
  1977年   14346篇
  1976年   13143篇
  1975年   13702篇
  1974年   16072篇
  1973年   15382篇
  1972年   14169篇
  1971年   13035篇
  1970年   11869篇
  1969年   11095篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
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   
3.
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   
4.
5.
6.
Neuroscience and Behavioral Physiology - The question of the involvement of impairments to the metabolism of melatonin and its precursors (tryptophan and serotonin) in the development of...  相似文献   
7.
Patients admitted to intensive care after cardiac arrest are at risk of circulatory shock and early mortality due to cardiovascular failure. The aim of this study was to evaluate the ability of the veno-arterial pCO2 difference (∆pCO2; central venous CO2 – arterial CO2) and lactate to predict early mortality in postcardiac arrest patients. This was a pre-planned prospective observational sub-study of the target temperature management 2 trial. The sub-study patients were included at five Swedish sites. Repeated measurements of ∆pCO2 and lactate were conducted at 4, 8, 12, 16, 24, 48, and 72 h after randomization. We assessed the association between each marker and 96-h mortality and their prognostic value for 96-h mortality. One hundred sixty-three patients were included in the analysis. Mortality at 96 h was 17%. During the initial 24 h, there was no difference in ∆pCO2 levels between 96-h survivors and non-survivors. ∆pCO2 measured at 4 h was associated with an increased risk of death within 96 h (adjusted odds ratio: 1.15; 95% confidence interval [CI]: 1.02–1.29; p = .018). Lactate levels were associated with poor outcome over multiple measurements. The area under the receiving operating curve to predict death within 96 h was 0.59 (95% CI: 0.48–0.74) and 0.82 (95% CI: 0.72–0.92) for ∆pCO2 and lactate, respectively. Our results do not support the use of ∆pCO2 to identify patients with early mortality in the postresuscitation phase. In contrast, non-survivors demonstrated higher lactate levels in the initial phase and lactate identified patients with early mortality with moderate accuracy.  相似文献   
8.
Bulletin of Experimental Biology and Medicine - Fast neutron therapy, which previously has demonstrated effective results, but along with a large number of complications, can again be considered a...  相似文献   
9.
Bulletin of Experimental Biology and Medicine - The psychopharmacological effects of a stimulator of functions of progenitor cells of the nervous tissue STAT3 inhibitor (STAT3 Inhibitor XIV, LLL12)...  相似文献   
10.
The purpose of this study was to provide an evidence base for colorectal cancer research activity that might influence policy, mainly at the national level. Improvements in healthcare delivery have lengthened life expectancy, but within a situation of increased cancer incidence. The disease burden of CRC has risen significantly, particularly in Africa, Asia and Latin America. Research is key to its control and reduction, but few studies have delineated the volume and funding of global research on CRC. We identified research papers in the Web of Science (WoS) from 2007 to 2021, and determined the contributions of the leading countries, the research domains studied, and their sources of funding. We identified 62 716 papers, representing 5.7% of all cancer papers. This percentage was somewhat disproportionate to the disease burden (7.7% in 2015), especially in Eastern Europe. International collaboration increased over the time period in almost all countries except in China. Genetics, surgery and prognosis were the leading research domains. However, research on palliative care and quality-of-life in CRC was lacking. In Western Europe, the main funding source was the charity sector, particularly in the UK, but in most other countries government played the leading role, especially in China and the USA. There was little support from industry. Several Asian countries provided minimal contestable funding, which may have reduced the impact of their CRC research. Certain countries must perform more CRC research overall, especially in domains such as screening, palliative care and quality-of-life. The private-non-profit sector should be an alternative source of support.  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