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   404篇
  免费   25篇
电工技术   3篇
化学工业   161篇
金属工艺   2篇
机械仪表   10篇
建筑科学   14篇
矿业工程   4篇
能源动力   6篇
轻工业   55篇
水利工程   2篇
石油天然气   1篇
无线电   20篇
一般工业技术   78篇
冶金工业   31篇
自动化技术   42篇
  2023年   5篇
  2022年   34篇
  2021年   45篇
  2020年   10篇
  2019年   13篇
  2018年   11篇
  2017年   16篇
  2016年   12篇
  2015年   10篇
  2014年   28篇
  2013年   14篇
  2012年   25篇
  2011年   24篇
  2010年   23篇
  2009年   20篇
  2008年   19篇
  2007年   14篇
  2006年   16篇
  2005年   9篇
  2004年   7篇
  2003年   4篇
  2002年   7篇
  2001年   5篇
  2000年   6篇
  1999年   7篇
  1998年   7篇
  1997年   6篇
  1996年   5篇
  1994年   2篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1974年   2篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
  1965年   1篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1955年   1篇
排序方式: 共有429条查询结果,搜索用时 31 毫秒
221.
2‐Azetidinones, commonly known as β‐lactams, are well‐known heterocyclic compounds. Herein we described the synthesis and biological evaluation of a series of novel β‐lactams. In vitro inhibition assays against HDAC isoforms showed an interesting isoform‐selectivity of these compounds towards HDAC6 and HDAC8. The isoform selectivity changed in response to modification of the azetidinone‐ring nitrogen atom substituent. The presence of an N‐thiomethyl group is a prerequisite for the activity of these compounds in the micromolar range towards HDAC8.  相似文献   
222.
Type 2 diabetes (T2D) represents one of the major health issues of this century. Despite the availability of an increasing number of anti-hyperglycemic drugs, a significant proportion of patients are inadequately controlled, thus highlighting the need for novel biomarkers to guide treatment selection. MicroRNAs (miRNAs) are small non-coding RNAs, proposed as useful diagnostic/prognostic markers. The aim of our study was to identify a miRNA signature occurring in responders to glucagon-like peptide 1 receptor agonists (GLP1-RA) therapy. We investigated the expression profile of eight T2D-associated circulating miRNAs in 26 prospectively evaluated diabetic patients in whom GLP1-RA was added to metformin. As expected, GLP1-RA treatment induced significant reductions of HbA1c and body weight, both after 6 and 12 months of therapy. Of note, baseline expression levels of the selected miRNAs revealed two distinct patient clusters: “high expressing” and “low expressing”. Interestingly, a significantly higher percentage of patients in the high expression group reached the glycemic target after 12 months of treatment. Our findings suggest that the evaluation of miRNA expression could be used to predict the likelihood of an early treatment response to GLP1-RA and to select patients in whom to start such treatment, paving the way to a personalized medicine approach.  相似文献   
223.
In recent decades, interest in natural compounds has increased exponentially due to their numerous beneficial properties in the treatment of various acute and chronic diseases. A group of plant derivatives with great scientific interest is terpenic compounds. Among the plants richest in terpenes, the genus Ferula L. is one of the most representative, and ferutinin, the most common sesquiterpene, is extracted from the leaves, rhizome, and roots of this plant. As reported in the scientific literature, ferutinin possesses antioxidant and anti-inflammatory properties, as well as valuable estrogenic properties. Neurodegenerative and demyelinating diseases are devastating conditions for which a definite cure has not yet been established. The mechanisms involved in these diseases are still poorly understood, and oxidative stress is considered to be both a key modulator and a common denominator. In the proposed experimental system, co-cultured human neurons (SH-SY5Y) and human oligodendrocytes (MO3.13) were treated with the pro-inflammatory agent lipopolysaccharide at a concentration of 1 μg/mL for 24 h or pretreated with ferutinin (33 nM) for 24 h and subsequently exposed to lipopolysaccharide 1 μg/mL for 24 h. Further studies would, however, be needed to establish whether this natural compound can be used as a support strategy in pathologies characterized by progressive inflammation and oxidative stress phenomena.  相似文献   
224.
We present the fabrication and electrical characterization of a flexible hybrid composite structure using aligned multiwall carbon nanotube arrays in a poly(dimethylsiloxane) (PDMS) matrix. Using lithographically patterned nanotube arrays, one can make these structures at any length scale from submicrometer levels to bulk quantities. The PDMS matrix undergoes excellent conformal filling within the dense nanotube network, giving rise to extremely flexible conducting structures with unique electromechanical properties. We demonstrate its robustness against high stress conditions, under which the composite is found to retain its conducting nature. We also demonstrate that these structures can be utilized directly as flexible field-emission devices. Our devices show some of the best field-enhancement factors and turn-on electric fields reported so far.  相似文献   
225.
We present a technique for the organization of pre-synthesized nanoparticles on hard substrates, using block copolymer films as sacrificial templates. A thin block copolymer film is dip-coated on the substrate of interest and the sample is exposed to a solution containing nanoparticles. Spontaneous preferential adsorption of the nanoparticles on one phase of the block copolymer film results in their lateral organization. An oxygen plasma etch is used to remove the polymer film; the nanoparticles end up organized on the substrate. We demonstrate that this is a general approach for the patterning of inorganic nanoparticles on hard substrates, showing the organization of metal and semiconductor nanoparticles having different chemistries at the particle/solvent and solvent/polymer interfaces. The nanoparticle patterns that we present have typical periodicities in the nanometer scale. In some cases, microcontact printing is used to create a double length scale of organization, on the micrometer and on the nanometer level. The characteristic periodicity of the template is studied with respect to the nanoparticle size in order to optimize the organization. Finally, we describe how to extend this technique for the production of continuous gold nanowires on hard substrates. We expect that the flexibility of this approach and the degree of control that can be obtained over nanoparticle organization should make it a powerful tool for nanoscale fabrication.  相似文献   
226.
Multi-walled carbon nanotubes were synthesized by chemical vapor deposition from pure toluene and toluene/diazine mixtures using ferrocene as a catalyst precursor at 760 degrees C. As recently announced, characterization of the resulting nanotube films showed that, unlike pure carbon nanotubes, those grown in the presence of nitrogen have an extremely high degree of internal order, both in terms of the uniform chirality in the nanotube walls and of the crystallographic register between them. Here, the structure, defects, and morphology of the nanotubes were analyzed in depth using advanced electron microscopy techniques, and compared with existing models and observations. Nitrogen, which seems to be responsible for the dramatic structural order, was found to segregate preferentially within the core of the nanotubes.  相似文献   
227.
228.
Dairy foods represent an important sector of the food market for their nutritional qualities and their organoleptic characteristics, which are often linked to tradition and to region. These products are typically protected by labels such as PDO (Protected Designation of Origin) and PGI (Protected Geographical Indication). Real-time PCR (qPCR) is a fundamental tool in “Food Genomics;” a discipline concerned with the residual DNA in food, which, alongside traditional physical and chemical methods, is frequently used to determine product safety, quality and authenticity. Compared to conventional or “end-point” PCR, qPCR incorporates continuous monitoring of reaction progress, thereby enabling quantification of target DNA. This review describes qPCR applications to the analysis of microbiota, and to the identification of the animal species source of milk from which dairy products have been made. These are important aspects for ensuring safety and authenticity. The various applications of qPCR are discussed, as well as advantages and disadvantages in comparison with other analytical methods.  相似文献   
229.
Traceability of olive oils is relevant not only in assessing their origin, but also in protecting against frauds. Here, we present an improvement of the assay previously developed for the genotyping of forty-nine frequently grown Mediterranean olive cultivars by ligation detection reaction (LDR)/universal array (UA), refining the entire procedure in order to address DNA extracted from monovarietal olive oils. Firstly, a simple and robust protocol to extract amplifiable DNA from olive oil was developed. Then, the SNP-containing DNA sequences were simultaneous amplified by multiplex PCR and used on a LDR-UA platform, which gave precise and accurate genotype results. Thirteen out of the seventeen investigated SNPs were amplifiable in multiplex PCR, and were sufficient to unequivocally discriminate the forty-nine cultivars. The availability of this semi-automated SNP genotyping assay should help food testing laboratories to verify the origin and authenticity of monovarietal extra-virgin olive oils. C. Consolandi and L. Palmieri equally contributed to this research paper.  相似文献   
230.
Cancer accounted for 13% of all deaths worldwide in 2005. Although early detection is critical for the successful treatment of many cancers, there are sensitivity limitations associated with current detection methodologies. Furthermore, many traditional anticancer drug treatments exhibit limited efficacy and cause high morbidity. The unique physical properties of nanoscale materials can be utilized to produce novel and effective sensors for cancer diagnosis, agents for tumor imaging, and therapeutics for cancer treatment. Functionalizing inorganic nanoparticles with biocompatible polymers and natural or rationally designed biomolecules offers a route towards engineering responsive and multifunctional composite systems. Although only a few such innovations have reached human clinical trial to date, nanocomposite materials based on functionalized metal and semiconductor nanoparticles promise to transform the way cancer is diagnosed and treated. This review summarizes the current state-of-the-art in the development of inorganic nanocomposites for cancer-related applications.  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