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   780篇
  免费   76篇
  国内免费   3篇
电工技术   3篇
化学工业   302篇
金属工艺   7篇
机械仪表   20篇
建筑科学   33篇
矿业工程   2篇
能源动力   10篇
轻工业   231篇
水利工程   8篇
石油天然气   1篇
无线电   24篇
一般工业技术   107篇
冶金工业   25篇
原子能技术   3篇
自动化技术   83篇
  2024年   2篇
  2023年   11篇
  2022年   43篇
  2021年   65篇
  2020年   26篇
  2019年   25篇
  2018年   22篇
  2017年   35篇
  2016年   43篇
  2015年   27篇
  2014年   41篇
  2013年   63篇
  2012年   51篇
  2011年   55篇
  2010年   47篇
  2009年   39篇
  2008年   52篇
  2007年   41篇
  2006年   35篇
  2005年   28篇
  2004年   22篇
  2003年   17篇
  2002年   12篇
  2001年   6篇
  2000年   7篇
  1999年   15篇
  1998年   4篇
  1997年   3篇
  1996年   8篇
  1994年   4篇
  1993年   3篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1987年   1篇
  1985年   1篇
排序方式: 共有859条查询结果,搜索用时 15 毫秒
851.
852.
The purpose of this work was to evaluate coconut oil's effect on lipid metabolism-related diseases and immune response using in vitro models. The coconut oil doses were selected according to the results of the safety evaluation performed through genotoxicity and cytotoxicity tests. Then its capacity to modulate obesity-related metabolism was evaluated by measuring adipolysis in 3T3-L1 differentiated adipocytes and hepatic lipid accumulation in hepatocytes (Hep G2). The immunomodulatory activity was evaluated using Caco-2 cells and quantifying pro-inflammatory cytokines’ production (IL-6, IL-8, and TNF-α). Coconut oil, mainly comprised of medium-chain fatty acids (>60% of total fatty acids), showed a high antioxidant capacity (125.76 ± 11.63 µM trolox equivalent/mL). The results showed that coconut oil was capable of reducing 68% of the lipid accumulation in hepatocytes and 42% in adipocytes. It was also capable of modulating the immune response in IL-1β Caco-2 stimulated cells, reducing IL-6 secretion (22% in the presence of 10 mg/mL of coconut oil and by 19% when 15 mg/mL) and TNF-α secretion (90% and 42% in the presence of 15 or 10 mg/mL of coconut oil, respectively). In short, coconut oil shows great potential for the development of functional foods and nutraceuticals targeting lipid metabolism-related diseases. Practical applications: This study describes the impact of organic virgin coconut oil on obesity-related metabolism and immune response. Despite the high content of saturated fatty acids, this vegetable oil has several beneficial effects in the obesity context by the reduction of lipid accumulation. Coconut oil can reduce lipid accumulation in hepatocytes and adipocytes. Coconut oil is capable of modulating the immune response in gut cells.  相似文献   
853.
With the objective of creating an electro-responsive and antimicrobial device suitable as delivery system for Rose Bengal (RB) to the skin, a hybrid hydrogel combining Chitosan (CS) and Graphene Oxide (GO) are designed, serving as functional polymer support and active filling element, respectively. The hybrid system, synthesized using tripolyphosphate as a crosslinker via ionic gelation, shows a uniform and homogeneous surface, as verified by SEM investigations, high biocompatibility when tested on human fibroblast lung cells MRC-5 cells, and biodegradability in phosphate buffered medium at physiological pH. Drug loading and release experiments, extensively analyzed using suitable mathematical modeling, shows the enhancement of the binding efficiency conferred by GO (534 and 979 mg g−1 for blank and hybrid hydrogels, respectively) and an electro-responsive behavior (maximum BR release of 36 and 23% at 0 and 12 V, respectively). Additionally, hybrid hydrogel is found to prevent the adhesion of methicillin-resistant Staphylococcus aureus and to kill the bacterial cells by taking advantage of the sustained release of the antimicrobial RB.  相似文献   
854.
855.
Cells process information via signal networks that typically involve multiple components which are interconnected by feedback loops. The combination of acute optogenetic perturbations and microscopy-based fluorescent response readouts enables the direct investigation of causal links in such networks. However, due to overlaps in spectra of photosensitive and fluorescent proteins, current approaches that combine these methods are limited. Here, we present an improved chemo-optogenetic approach that is based on switch-like perturbations induced by a single, local pulse of UV light. We show that this approach can be combined with parallel monitoring of multiple fluorescent readouts to directly uncover relations between signal network components. We present the application of this technique to directly investigate feedback-controlled regulation in the cell contraction signal network that includes GEF-H1, Rho and Myosin, and functional interactions of this network with tumor relevant RhoA G17 mutants.  相似文献   
856.
The non-invasive detection of chilling injury (CI) symptoms in banana may potentially be approached by means of monitoring changes in the pigment contents and texture of the exocarp. In the present study, laser diodes emitting at 660 and 785 nm were applied to acquire images of backscattered light from intact banana fruits. The idea was to monitor chlorophyll and texture changes by means of relevant wavelengths, respectively. Bananas were stored for 2 days at 13 °C (control), 6 °C (chilling temperature), and subsequently 1 day at ambient temperature to allow the symptom development. Parameters obtained from the backscattering images and their combinations were applied for detecting chilling injury. Significant (P < 0.05) interaction of backscattering properties and treatment factors (temperature, ripening stage, and treatment time) were found. Classification of control and chill-injured samples in ripe fruits measured at 660 nm and 785 nm resulted in misclassification error as low as 6% and 8% for early detection, and 0.67% and 1.33% for detection after storage, respectively. The physiological relevance of the variation measured at the two wavelengths was pointed out by means of destructive pigment and water analyses.  相似文献   
857.
Metallo-β-lactamases (MBLs) are increasingly involved as a major mechanism of resistance to carbapenems in relevant opportunistic Gram-negative pathogens. Unfortunately, clinically efficient MBL inhibitors still represent an unmet medical need. We previously reported several series of compounds based on the 1,2,4-triazole-3-thione scaffold. In particular, Schiff bases formed between diversely 5-substituted-4-amino compounds and 2-carboxybenzaldehyde were broad-spectrum inhibitors of VIM-type, NDM-1 and IMP-1 MBLs. Unfortunately, these compounds were unable to restore antibiotic susceptibility of MBL-producing bacteria, probably because of poor penetration and/or susceptibility to hydrolysis. To improve their microbiological activity, we synthesized and characterized compounds where the hydrazone-like bond of the Schiff base analogues was replaced by a stable ethyl link. This small change resulted in a narrower inhibition spectrum, as all compounds were poorly or not inhibiting NDM-1 and IMP-1, but showed a significantly better activity on VIM-type enzymes, with Ki values in the μM to sub-μM range. The resolution of the crystallographic structure of VIM-2 in complex with one of the best inhibitors yielded valuable information about their binding mode. Interestingly, several compounds were shown to restore the β-lactam susceptibility of VIM-type-producing E. coli laboratory strains and also of K. pneumoniae clinical isolates. In addition, selected compounds were found to be devoid of toxicity toward human cancer cells at high concentration, thus showing promising safety.  相似文献   
858.
Polymorphic phases and collective phenomena—such as charge density waves (CDWs)—in transition metal dichalcogenides (TMDs) dictate the physical and electronic properties of the material. Most TMDs naturally occur in a single given phase, but the fine-tuning of growth conditions via methods such as molecular beam epitaxy (MBE) allows to unlock otherwise inaccessible polymorphic structures. Exploring and understanding the morphological and electronic properties of new phases of TMDs is an essential step to enable their exploitation in technological applications. Here, scanning tunneling microscopy (STM) is used to map MBE-grown monolayer (ML) TaTe2. This work reports the first observation of the 1H polymorphic phase, coexisting with the 1T, and demonstrates that their relative coverage can be controlled by adjusting synthesis parameters. Several superperiodic structures, compatible with CDWs, are observed to coexist on the 1T phase. Finally, this work provides theoretical insight on the delicate balance between Te…Te and Ta–Ta interactions that dictates the stability of the different phases. The findings demonstrate that TaTe2 is an ideal platform to investigate competing interactions, and indicate that accurate tuning of growth conditions is key to accessing metastable states in TMDs.  相似文献   
859.
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