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   1100篇
  免费   59篇
电工技术   2篇
化学工业   286篇
金属工艺   7篇
机械仪表   17篇
建筑科学   67篇
矿业工程   3篇
能源动力   23篇
轻工业   164篇
水利工程   7篇
石油天然气   3篇
无线电   47篇
一般工业技术   153篇
冶金工业   259篇
原子能技术   5篇
自动化技术   116篇
  2023年   15篇
  2022年   68篇
  2021年   78篇
  2020年   27篇
  2019年   28篇
  2018年   32篇
  2017年   40篇
  2016年   36篇
  2015年   18篇
  2014年   32篇
  2013年   62篇
  2012年   60篇
  2011年   56篇
  2010年   58篇
  2009年   52篇
  2008年   61篇
  2007年   38篇
  2006年   24篇
  2005年   24篇
  2004年   23篇
  2003年   26篇
  2002年   27篇
  2001年   15篇
  2000年   10篇
  1999年   12篇
  1998年   20篇
  1997年   16篇
  1996年   20篇
  1995年   18篇
  1994年   15篇
  1993年   10篇
  1992年   14篇
  1991年   5篇
  1990年   12篇
  1989年   9篇
  1988年   7篇
  1987年   9篇
  1986年   7篇
  1985年   9篇
  1984年   9篇
  1983年   9篇
  1982年   5篇
  1981年   5篇
  1979年   3篇
  1978年   6篇
  1977年   4篇
  1976年   3篇
  1974年   3篇
  1970年   3篇
  1964年   2篇
排序方式: 共有1159条查询结果,搜索用时 31 毫秒
141.
142.
Free fatty acid receptor 2 (FFA2) is a sensor for short-chain fatty acids that has been identified as an interesting potential drug target for treatment of metabolic and inflammatory diseases. Although several ligand series are known for the receptor, there is still a need for improved compounds. One of the most potent and frequently used antagonists is the amide-substituted phenylbutanoic acid known as CATPB ( 1 ). We here report the structure-activity relationship exploration of this compound, leading to the identification of homologues with increased potency. The preferred compound 37 (TUG-1958) was found, besides improved potency, to have high solubility and favorable pharmacokinetic properties.  相似文献   
143.
Over the past decade, telomeres have attracted increasing attention due to the role they play in human fertility. However, conflicting results have been reported on the possible association between sperm telomere length (STL) and leukocyte telomere length (LTL) and the quality of the sperm parameters. The aim of this study was to run a comprehensive study to investigate the role of STL and LTL in male spermatogenesis and infertility. Moreover, the association between the sperm parameters and 11 candidate single nucleotide polymorphisms (SNPs), identified in the literature for their association with telomere length (TL), was investigated. We observed no associations between sperm parameters and STL nor LTL. For the individual SNPs, we observed five statistically significant associations with sperm parameters: considering a p < 0.05. Namely, ACYP2˗rs11125529 and decreased sperm motility (p = 0.03); PXK˗rs6772228 with a lower sperm count (p = 0.02); NAF1˗rs7675998 with increased probability of having abnormal acrosomes (p = 0.03) and abnormal flagellum (p = 0.04); ZNF208˗rs8105767 and reduction of sperms with normal heads (p = 0.009). This study suggests a moderate involvement of telomere length in male fertility; however, in our analyses four SNPs were weakly associated with sperm variables, suggesting the SNPs to be pleiotropic and involved in other regulatory mechanisms independent of telomere homeostasis, but involved in the spermatogenic process.  相似文献   
144.
Parkinsons Disease (PD) is the second most common neurodegenerative disease worldwide, and is characterized by a progressive degeneration of dopaminergic neurons. Without an effective treatment, it is crucial to find new therapeutic options to fight the neurodegenerative process, which may arise from marine resources. Accordingly, the goal of the present work was to evaluate the ability of the monoterpenoid lactone Loliolide, isolated from the green seaweed Codium tomentosum, to prevent neurological cell death mediated by the neurotoxin 6-hydroxydopamine (6-OHDA) on SH-SY5Y cells and their anti-inflammatory effects in RAW 264.7 macrophages. Loliolide was obtained from the diethyl ether extract, purified through column chromatography and identified by NMR spectroscopy. The neuroprotective effects were evaluated by the MTT method. Cells’ exposure to 6-OHDA in the presence of Loliolide led to an increase of cells’ viability in 40%, and this effect was mediated by mitochondrial protection, reduction of oxidative stress condition and apoptosis, and inhibition of the NF-kB pathway. Additionally, Loliolide also suppressed nitric oxide production and inhibited the production of TNF-α and IL-6 pro-inflammatory cytokines. The results suggest that Loliolide can inspire the development of new neuroprotective therapeutic agents and thus, more detailed studies should be considered to validate its pharmacological potential.  相似文献   
145.
146.
147.
148.
Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzes the oxidative cleavage of l -Tryptophan (l -Trp) to yield N-formyl-kynurenine in the first and rate limiting step of the kynurenine pathway. Bioactive metabolites, involved in the regulation of important immunological responses and neurological processes, are then produced by downstream enzymes along the pathway. Inhibitors of IDO1 are being designed and developed as therapeutic agents for immuno-oncology. In this work, we investigated the molecular recognition path of l -Trp to IDO1, integrating biophysical methods with supervised molecular dynamics (suMD) and mutagenesis experiments. Results allowed disclosing for the first time high and low dissociation constants of l -Trp to IDO1, and the presence of a metastable interaction site located at the upper part of a channel whose borders are defined by the EF-loop and the C-terminal part of the JK-loop. Collectively, our results provide new clues for the design of next-generation IDO1 ligands.  相似文献   
149.
This study characterised the main sweet beverages and food products marketed in Brazil regarding (i) the addition of sugar/sweeteners, (ii) nutritional profile and (iii) sugar claims. Results revealed that most of the beverages had added sweeteners, while food products were mainly sweetened with sugar. Moreover, >90% of the powdered products had added sweeteners. ‘Zero sugar’ (46%) and ‘light’ (55%) were the most common sugar claims in sugar-free and reduced-sugar products, respectively. Powdered products, soya drinks and baked products included claims less frequently. Regarding the nutritional profile, beverages with sugar substitution had a proportionally greater reduction in the content of carbohydrates and calories (up to 99%, for both) in relation to food (<82% and <85%, respectively). The results suggest that reducing sugar in solid foods remains a greater challenge than in beverages and that this reduction has less impact on the final energy density of foods.  相似文献   
150.
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