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   5551篇
  免费   274篇
  国内免费   26篇
耳鼻咽喉   81篇
儿科学   138篇
妇产科学   280篇
基础医学   733篇
口腔科学   278篇
临床医学   512篇
内科学   1265篇
皮肤病学   77篇
神经病学   593篇
特种医学   120篇
外科学   772篇
综合类   23篇
一般理论   5篇
预防医学   225篇
眼科学   107篇
药学   274篇
中国医学   9篇
肿瘤学   359篇
  2023年   28篇
  2022年   73篇
  2021年   130篇
  2020年   80篇
  2019年   132篇
  2018年   170篇
  2017年   118篇
  2016年   138篇
  2015年   161篇
  2014年   210篇
  2013年   284篇
  2012年   403篇
  2011年   410篇
  2010年   258篇
  2009年   221篇
  2008年   359篇
  2007年   360篇
  2006年   369篇
  2005年   297篇
  2004年   256篇
  2003年   262篇
  2002年   244篇
  2001年   75篇
  2000年   48篇
  1999年   59篇
  1998年   55篇
  1997年   60篇
  1996年   42篇
  1995年   33篇
  1994年   24篇
  1993年   24篇
  1992年   46篇
  1991年   38篇
  1990年   32篇
  1989年   35篇
  1988年   25篇
  1987年   24篇
  1986年   20篇
  1985年   17篇
  1984年   19篇
  1983年   14篇
  1982年   14篇
  1981年   13篇
  1980年   14篇
  1978年   14篇
  1977年   15篇
  1976年   15篇
  1975年   10篇
  1974年   16篇
  1969年   11篇
排序方式: 共有5851条查询结果,搜索用时 9 毫秒
51.
Aflatoxins (AFs) remain the main concern for the agricultural and dairy industries due to their effects on the performances and quality of livestock production. Aflatoxins are always unavoidable and should be monitored. The objective of this paper is to bring to light a significant volume of data on AF contamination in several animal feed ingredients in Northern Italy. The Regional Breeders Association of Lombardy has been conducting a survey program to monitor mycotoxin contamination in animal feeds, and in this paper, we present data relating to AFB1 contamination. In most cases (95%), the concentrations were low enough to ensure compliance with the European Union’s (EU’s) maximum admitted levels for animal feed ingredients. However, the data show a high variability in AF contamination between different matrices and, within the same matrix, a high variability year over year. High levels of AFs were detected in maize and cotton, especially in the central part of the second decade of this century, i.e., 2015–2018, which has shown a higher risk of AF contamination in feed materials in Northern Italy. Variability due to climate change and the international commodity market affect future prospects to predict the presence of AFs. Supplier monitoring and control and reduced buying of contaminated raw materials, as well as performing analyses of each batch, help reduce AF spread.  相似文献   
52.
53.
54.
Insect cell-baculovirus expression vector system is one of the most established platforms to produce biological products, and it plays a fundamental role in the context of COVID-19 emergency, providing recombinant proteins for treatment, diagnosis, and prevention. SARS-CoV-2 infection is mediated by the interaction of the spike glycoprotein trimer via its receptor-binding domain (RBD) with the host’s cellular receptor. As RBD is required for many applications, in the context of pandemic it is important to meet the challenge of producing a high amount of recombinant RBD (rRBD). For this reason, in the present study, we developed a process based on Sf9 insect cells to improve rRBD yield. rRBD was recovered from the supernatant of infected cells and easily purified by metal ion affinity chromatography, with a yield of 82% and purity higher than 95%. Expressed under a novel chimeric promoter (polh-pSeL), the yield of rRBD after purification was 21.1 ± 3.7 mg/L, which is the highest performance described in Sf9 cell lines. Finally, rRBD was successfully used in an assay to detect specific antibodies in COVID-19 serum samples. The efficient strategy herein described has the potential to produce high-quality rRBD in Sf9 cell line for diagnostic purpose.  相似文献   
55.
56.
In the current landscape of endothelial cell isolation for building in vitro models of the blood-brain barrier, our work moves towards reproducing the features of the neurovascular unit to achieve glial compliance through an innovative biomimetic coating technology for brain chronic implants. We hypothesized that the autologous origin of human brain microvascular endothelial cells (hBMECs) is the first requirement for the suitable coating to prevent the glial inflammatory response triggered by foreign neuroprosthetics. Therefore, this study established a new procedure to preserve the in vitro viability of hBMECs isolated from gray and white matter specimens taken from neurosurgery patients. Culturing adult hBMECs is generally considered a challenging task due to the difficult survival ex vivo and progressive reduction in proliferation of these cells. The addition of 10 nM β-estradiol 17-acetate to the hBMEC culture medium was found to be an essential and discriminating factor promoting adhesion and proliferation both after isolation and thawing, supporting the well-known protective role played by estrogens on microvessels. In particular, β-estradiol 17-acetate was critical for both freshly isolated and thawed female-derived hBMECs, while it was not necessary for freshly isolated male-derived hBMECs; however, it did counteract the decay in the viability of the latter after thawing. The tumor-free hBMECs were thus cultured for up to 2 months and their growth efficiency was assessed before and after two periods of cryopreservation. Despite the thermal stress, the hBMECs remained viable and suitable for re-freezing and storage for several months. This approach increasing in vitro viability of hBMECs opens new perspectives for the use of cryopreserved autologous hBMECs as biomimetic therapeutic tools, offering the potential to avoid additional surgical sampling for each patient.  相似文献   
57.
<正>Function of lactate:Lactate is a three-carbon molecule produced by glycolytic metabolism that is a metabolic waste product with no known use in clinical therapy.Conversely,it is a metabolite that the body should quickly guarantee the clearance.However,lactate is now recognized as a potential energy substrate,as well as an anti-inflammatory signaling molecule.These actions were first reported in adult animal models with a brain injury,including a traumatic brain injury and cerebral ische...  相似文献   
58.
59.
Background and aimHumor has been described as an effective coping strategy for dealing with chronic pain conditions; likewise, coping strategies predict some clinical outcomes after cognitive-behavioral therapy and mindfulness-based interventions. The present study aims to preliminarily explore the role of humor styles in predicting clinical changes after the multicomponent intervention (MINDSET) that combines mindfulness and psychoeducation for fibromyalgia (FM) patients.Material and methodsA subsample of 35 patients with FM of the EUDAIMON study, a randomized controlled trial, was used for the present study; linear regressions and Spearman's correlations were computed.ResultsAffiliative humor and positive/negative ratio humor styles had a unique predictive effect on self-reported clinical changes. Significant correlations between humor styles with functional impact and mindfulness facets were observed.ConclusionsSome humor styles may imply a better disposition in patients to learn and implement the concepts and resources that the intervention offered.  相似文献   
60.
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