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   177413篇
  免费   920篇
  国内免费   34篇
耳鼻咽喉   1166篇
儿科学   6668篇
妇产科学   3082篇
基础医学   16852篇
口腔科学   1618篇
临床医学   12489篇
内科学   31161篇
皮肤病学   695篇
神经病学   16577篇
特种医学   9007篇
外科学   29135篇
综合类   2315篇
预防医学   18131篇
眼科学   2803篇
药学   9653篇
中国医学   632篇
肿瘤学   16383篇
  2019年   34篇
  2018年   21940篇
  2017年   17381篇
  2016年   19525篇
  2015年   927篇
  2014年   832篇
  2013年   802篇
  2012年   6989篇
  2011年   21040篇
  2010年   18851篇
  2009年   11562篇
  2008年   19582篇
  2007年   21802篇
  2006年   633篇
  2005年   2292篇
  2004年   3525篇
  2003年   4481篇
  2002年   2612篇
  2001年   299篇
  2000年   446篇
  1999年   202篇
  1998年   237篇
  1997年   222篇
  1996年   107篇
  1995年   131篇
  1994年   132篇
  1993年   97篇
  1992年   60篇
  1991年   110篇
  1990年   141篇
  1989年   97篇
  1988年   75篇
  1987年   63篇
  1986年   36篇
  1985年   42篇
  1984年   39篇
  1983年   43篇
  1982年   48篇
  1981年   26篇
  1980年   70篇
  1978年   26篇
  1975年   31篇
  1970年   27篇
  1969年   26篇
  1939年   26篇
  1938年   64篇
  1937年   27篇
  1934年   33篇
  1932年   60篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The ongoing COVID-19 pandemic caused by the SARS-CoV-2 coronavirus has affected the health of tens of millions of people worldwide. In particular, in elderly and frail individuals the infection can lead to severe disease and even fatal outcomes. Although the pandemic is primarily a human health crisis its consequences are much broader with a tremendous impact on global economics and social systems. Vaccines are considered the most powerful measure to fight the pandemic and protect people from COVID-19. Based on the concerted activities of scientists, manufacturers and regulators, the urgent need for effective countermeasures has provoked the development and licensure of novel COVID-19 vaccines in an unprecedentedly fast and flexible manner within <1 year. To ensure the safety and efficacy of these novel vaccines during the clinical development and the routine use in post-licensure vaccination campaigns existing regulatory requirements and procedures had to be wisely and carefully adapted to allow for an expedited evaluation without compromising the thoroughness of the regulatory and scientific assessment. In this review, we describe the regulatory procedures, concepts and requirements applied to guide and promote the highly accelerated development and licensure of safe and efficacious COVID-19 vaccines in Europe.  相似文献   
2.
International Ophthalmology - To investigate the effect of “skin-only” upper eyelid blepharoplasty on corneal biomechanics and central as well as peripheral topographic/tomographic...  相似文献   
3.
4.
Annals of Surgical Oncology - The benefits of systematic re-excision (RE) after initial unplanned excision (UE) of soft tissue sarcoma (STS) are unknown. The aim of this study was to evaluate the...  相似文献   
5.
6.
Introduction The Nominal Group Technique (NGT) and Delphi Technique are consensus methods used in research that is directed at problem-solving, idea-generation, or determining priorities. While consensus methods are commonly used in health services literature, few studies in pharmacy practice use these methods. This paper provides an overview of the NGT and Delphi technique, including the steps involved and the types of research questions best suited to each method, with examples from the pharmacy literature. Methodology The NGT entails face-to-face discussion in small groups, and provides a prompt result for researchers. The classic NGT involves four key stages: silent generation, round robin, clarification and voting (ranking). Variations have occurred in relation to generating ideas, and how ‘consensus’ is obtained from participants. The Delphi technique uses a multistage self-completed questionnaire with individual feedback, to determine consensus from a larger group of ‘experts.’ Questionnaires have been mailed, or more recently, e-mailed to participants. When to use The NGT has been used to explore consumer and stakeholder views, while the Delphi technique is commonly used to develop guidelines with health professionals. Method choice is influenced by various factors, including the research question, the perception of consensus required, and associated practicalities such as time and geography. Limitations The NGT requires participants to personally attend a meeting. This may prove difficult to organise and geography may limit attendance. The Delphi technique can take weeks or months to conclude, especially if multiple rounds are required, and may be complex for lay people to complete.  相似文献   
7.
The ecotoxicological risk of pharmaceutical mixtures typically exceeds the risk of each individual compound, which calls specific attention to the fact that monitoring surveys routinely find complex pharmaceutical mixtures in various environmental compartments. However, although the body of evidence on the ecotoxicology of pharmaceutical mixtures is quite consistent, the current guidelines for the environmental risk assessment of pharmaceuticals often do not explicitly address mixture effects. Data availability and acceptable methods often limit such assessments. A tiered approach that begins with summing up individual risk quotients, i.e., the ratio between the predicted or measured environmental concentration and the predicted no effect concentration (PNEC) is therefore suggested in this paper, in order to improve the realism of the environmental risk assessment of pharmaceuticals. Additionally, the use of a mixture-specific assessment factor, as well as the classical mixture toxicity concepts of concentration addition and independent action is explored. Finally, specific attention is given to the exposure-based waiving of environmental risk assessments, as currently implemented in screening or pre-screening phases (tier 0 in Europe, categorical exclusion in the USA), since even low, individually non-toxic concentrations might combine to produce substantial mixture effects.  相似文献   
8.
Growth factors involved in neurogenesis and neuroplasticity could play a role in biological processes that drive depression recovery. Combined total sleep deprivation and morning light therapy (TSD + LT) can acutely reverse depressive symptoms, thus allowing to investigate the neurobiological correlates of antidepressant response. We tested if changes on plasma levels of Brain Derived Neurotrophic Factor (BDNF), S100 calcium binding protein B (S100-B), Stem Cell Factor (SCF), Insulin-like Growth Factor-Binding Protein 2 (IGFBP-2), Epidermal Growth Factor (EGF), Platelet-Derived Growth Factor-BB (PDGF-BB), and Vascular Endothelial Growth Factor (VEGF) are associated with response to TSD + LT in 26 inpatients affected by a major depressive episode in the course of bipolar disorder. Regional grey matter (GM) volumes were assessed at baseline, and BOLD fMRI neural responses to a moral valence decision task were recorded before and after treatment. 61.5 % of patients responded to treatment. SCF plasma levels increased significantly more in responders, and correlated with GM volumes in frontal and parietal cortical areas. The pattern of change of SCF also associated with both GM volumes and changes of BOLD fMRI neural responses in the anterior cingulate and medial prefrontal cortex. SCF is both a hematopoietic growth factor and a neurotrophic factor, involved in neuron-neuron and neuron-(micro) glia interactions, fostering neuronal growth and an anti-inflammatory milieu. We correlated SCF levels with antidepressant response and with functional and structural MRI measures in cortical areas that are involved in the cognitive generation and control of affect. SCF may be a candidate growth factor that contributes to neurotrophic and immune effects that are involved in the process of remission/recovery from depression.  相似文献   
9.
In this study, we have investigated small multitargeted molecules containing 2-aminopyrimidine scaffold that may further act as precursor for developing more potent antibacterials. An efficient route to 2-amino-1,4-dihydropyrimidines by using ultrasound irradiation as the energy source was developed. In silico density functional theory calculations illustrated that tin chloride-mediated Biginelli reaction to produce 2-amino-1,4-dihydropyrimidines has energetics quite accessible under the reaction conditions. Calculated minimum inhibitory concentrations against the various bacterial strains showed that compounds 3 and 11 displayed comparable in vitro activity to ciprofloxacin in Staphylococcus aureus strains and reduced potency in Escherichia coli strains. Further, we investigated in silico ADMET profiling of synthesized compounds in order to understand the mechanism of action that help in explaining in vitro results. Lead compounds 3, 6, and 11 are predicted to have acceptable pharmacokinetic/drug-like properties. Data mining and computational analysis were employed to derive compound promiscuity phenomenon. All the compounds were found nonsubstrate towards various aminergic G-protein coupled receptors, ion-channels, kinase inhibitor, nuclear receptor ligand, protease inhibitor, and enzyme inhibitor. Compound 3 was further investigated by in silico binding to different antibacterial targets. Binding energy data revealed that that these compounds have the ability to bind with other bacterial targets. Hence, combined in silico and in vitro studies shed insights into the mechanism of synthesis and antibacterial activity of 2-amino-1,4-dihydropyrimidines. Results of this study are promising and can be used for further investigation by medicinal chemists to explore their chemical functionalization and in vivo studies.  相似文献   
10.
Idarucizumab (Praxbind®), a humanized monoclonal antibody, is a specific reversal agent for the direct oral thrombin inhibitor dabigatran, available as its prodrug dabigatran etexilate (Pradaxa®). Idarucizumab is approved in several countries (including the USA, the EU, Canada and Australia) for use in adult patients on dabigatran when the reversal of its anticoagulant effects is required for emergency surgery/procedures or in the event of life-threatening or uncontrolled bleeding. In the ongoing pivotal RE-VERSE AD trial in these populations (n = 90), intravenous idarucizumab 5 g reversed dabigatran-induced prolongation of dilute thrombin time (dTT) and ecarin clotting time (ECT) within minutes. The median maximum percentage reversal was 100 % for both assays (primary endpoint). Idarucizumab normalized dTT and ECT in 88?98 % of patients who had elevated levels at baseline. After idarucizumab administration, bleeding stopped in 97 % of evaluable patients in the bleeding cohort within 24 h (median time to cessation of bleeding was 11.4 h), and the rate of normal intraoperative haemostasis was 92 % in the surgical cohort. Idarucizumab was generally well tolerated. In conclusion, idarucizumab is a unique and specific treatment option for the reversal of the anticoagulant effects of dabigatran in adult patients requiring emergency procedures or in the event of life-threatening or uncontrolled bleeding.  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