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   2243篇
  免费   125篇
  国内免费   6篇
电工技术   26篇
综合类   9篇
化学工业   557篇
金属工艺   36篇
机械仪表   77篇
建筑科学   109篇
矿业工程   2篇
能源动力   94篇
轻工业   342篇
水利工程   9篇
石油天然气   5篇
武器工业   1篇
无线电   208篇
一般工业技术   425篇
冶金工业   81篇
原子能技术   18篇
自动化技术   375篇
  2024年   3篇
  2023年   22篇
  2022年   31篇
  2021年   157篇
  2020年   62篇
  2019年   69篇
  2018年   88篇
  2017年   83篇
  2016年   77篇
  2015年   72篇
  2014年   122篇
  2013年   182篇
  2012年   118篇
  2011年   191篇
  2010年   136篇
  2009年   120篇
  2008年   124篇
  2007年   109篇
  2006年   88篇
  2005年   68篇
  2004年   64篇
  2003年   57篇
  2002年   51篇
  2001年   30篇
  2000年   15篇
  1999年   18篇
  1998年   23篇
  1997年   21篇
  1996年   15篇
  1995年   17篇
  1994年   16篇
  1993年   12篇
  1992年   6篇
  1991年   5篇
  1990年   5篇
  1989年   9篇
  1988年   5篇
  1987年   3篇
  1985年   5篇
  1984年   15篇
  1983年   7篇
  1982年   7篇
  1981年   5篇
  1980年   3篇
  1979年   7篇
  1977年   5篇
  1976年   3篇
  1974年   4篇
  1967年   3篇
  1966年   3篇
排序方式: 共有2374条查询结果,搜索用时 234 毫秒
1.
Herein, we assessed the effect of full native peptide of amyloid-beta (Aβ) (1-42) and its fragments (25-35 and 35-25) on tissue transglutaminase (TG2) and its isoforms (TG2-Long and TG2-Short) expression levels on olfactory ensheathing cells (OECs). Vimentin and glial fibrillary acid protein (GFAP) were also studied. The effect of the pre-treatment with indicaxanthin from Opuntia ficus-indica fruit on TG2 expression levels and its isoforms, cell viability, total reactive oxygen species (ROS), superoxide anion (O2), and apoptotic pathway activation was assessed. The levels of Nestin and cyclin D1 were also evaluated. Our findings highlight that OECs exposure to Aβ(1-42) and its fragments induced an increase in TG2 expression levels and a different expression pattern of its isoforms. Indicaxanthin pre-treatment reduced TG2 overexpression, modulating the expression of TG2 isoforms. It reduced total ROS and O2 production, GFAP and Vimentin levels, inhibiting apoptotic pathway activation. It also induced an increase in the Nestin and cyclin D1 expression levels. Our data demonstrated that indicaxanthin pre-treatment stimulated OECs self-renewal through the reparative activity played by TG2. They also suggest that Aβ might modify TG2 conformation in OECs and that indicaxanthin pre-treatment might modulate TG2 conformation, stimulating neural regeneration in Alzheimer’s disease.  相似文献   
2.
Extracellular vesicles (EVs) are a heterogeneous group of cell-derived submicron vesicles released under physiological or pathological conditions. EVs mediate the cellular crosstalk, thus contributing to defining the tumor microenvironment, including in epithelial ovarian cancer (EOC). The available literature investigating the role of EVs in EOC has been reviewed following PRISMA guidelines, focusing on the role of EVs in early disease diagnosis, metastatic spread, and the development of chemoresistance in EOC. Data were identified from searches of Medline, Current Contents, PubMed, and from references in relevant articles from 2010 to 1 April 2020. The research yielded 194 results. Of these, a total of 36 papers, 9 reviews, and 27 original types of research were retained and analyzed. The literature findings demonstrate that a panel of EV-derived circulating miRNAs may be useful for early diagnosis of EOC. Furthermore, it appears clear that EVs are involved in mediating two crucial processes for metastatic and chemoresistance development: the epithelial–mesenchymal transition, and tumor escape from the immune system response. Further studies, more focused on in vivo evidence, are urgently needed to clarify the role of EV assessment in the clinical management of EOC patients.  相似文献   
3.
Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism.  相似文献   
4.
Calcium (Ca) is a key micronutrient of high relevance for human nutrition that also influences the texture and taste of dairy products and their processability. In bovine milk, Ca is presented in several speciation forms, such as complexed with other milk components or free as ionic calcium while being distributed between colloidal and serum phases of milk. Partitioning of Ca between these phases is highly dynamic and influenced by factors, such as temperature, ionic strength, pH, and milk composition. Processing steps used during the manufacture of dairy products, such as preconditioning, concentration, acidification, salting, cooling, and heating, all contribute to modify Ca speciation and partition, thereby influencing product functionality, product yield, and fouling of equipment. This review aims to provide a comprehensive understanding of the influence of Ca partition on dairy products properties to support the development of kinetics models to reduce product losses and develop added-value products with improved functionality. To achieve this objective, approaches to separate milk phases, analytical approaches to determine Ca partition and speciation, the role of Ca on protein–protein interactions, and their influence on processing of dairy products are discussed.  相似文献   
5.
6.
The Italian economy is characterised by a large number of micro-firms and small firms and by a long-lasting gap between North and South Italy. Therefore, global shocks – such as the Great Recession – have had a heterogeneous impact at the local level: the collapse in private demand was unequally distributed across different products, services and regions. The aim of this paper, therefore, is to evaluate the impact of the Great Recession on firm's survival for the universe of Italian firms in the light of two relevant indicators: local exposure to crisis and local demand shocks. The results suggest a strong negative impact of local demand shocks on the survival of firms, whereas the degree of exposure to the crisis generally has a weak effect.  相似文献   
7.
8.
There has been an increasing interest in the wooden barrel aging of beer in breweries worldwide. Monitoring of the barrel aging process relies mostly on changes in sensory parameters over time. This may be difficult for teams or brewers with little or no appropriate experience. The beer sensory wheel presents a broad approach to sensory aspects and generalised attributes for many beer styles. Accordingly, this tool may result in confusion through excessive visual information. The work reported here is based on literature research and sensory panel analysis employing ultra-flash profile with the aim to build a new visual tool for wooden barrel aged beer. This will aid the evaluation, training and quality assessment of barrel aged beer. It also provides specific terminology to describe the sensory changes during the barrel aging process. This approach was used to elucidate the characteristics of different wood species (amburana, cabreúva and American oak), and evaluate the flavour transformation of wooden barrel aged beer compared to non-aged beer. The barrel aged beer wheel comprises attributes and references for flavour evaluation and also terms that define the main transformational pathways, namely oxidation, wood extraction and biotransformation. The wheel described here is intended to meet academic and professional needs for the quality assessment of wooden barrel aged beer based on sensory analysis. © 2020 The Institute of Brewing & Distilling  相似文献   
9.
10.
The aim of the review was to evaluate patient and treatment characteristics for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with PSMA radioligand therapy (PRLT) associated with above-average outcome. The systematic review and meta-analysis followed recommendations by the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA). We searched for publications in PubMed, Embase, and ClinicalTrials.gov up to 31 September 2020. Thirty-six publications and four duplicates reported 2346 patients. Nearly two-thirds of the patients had bone metastases. Median overall survival (OS) was 16 months. Asymptomatic patients and patients with only lymph node metastases lived longer than symptomatic patients and patients with more extensive metastases. Patients treated with an intensified schedule of 177Lu PRLT lived longer than those treated with a conventional schedule. Half of the patients obtained a PSA decline ≥ 50% and these patients lived longer than those with less PSA decline. Approximately 10% of the patients developed hematologic toxicity with anemia grade 3 as the most severe adverse effect. Characteristics for patients, cancer, restaging, and PRLT predict above average overall survival following treatment with PRLT.  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