首页 | 官方网站   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   287篇
  免费   29篇
工业技术   316篇
  2024年   1篇
  2023年   4篇
  2022年   17篇
  2021年   96篇
  2020年   24篇
  2019年   19篇
  2018年   13篇
  2017年   11篇
  2016年   17篇
  2015年   13篇
  2014年   15篇
  2013年   14篇
  2012年   27篇
  2011年   12篇
  2010年   7篇
  2009年   7篇
  2008年   4篇
  2007年   7篇
  2006年   3篇
  2005年   2篇
  2003年   3篇
排序方式: 共有316条查询结果,搜索用时 15 毫秒
91.
Guiding a transition to low carbon electricity requires a good understanding of the substitution of old by new technologies in the electricity industry. With the aim of explaining historical change from coal to gas in the British electricity industry, we develop a formal model of technological change, where energy technologies diffuse through the construction of new power plants. We considered two model versions: with rational and boundedly rational investors. In each model version, we look at the causal relations between price and output setting mechanisms, fuel and labour use, and investment decisions for different institutional arrangements. We quantify model parameters on data for the United Kingdom. We find that the version of the model with rational investors is capable of replicating well core features of UK electricity history. This includes a rapid diffusion of gas in electricity production, the evolution of the average size of newly installed plants, and a high percentage of electricity sales covered by (forward) contracts-for-difference. In this model setting, nuclear and renewable energies have no chance to diffuse on the market. In the version of the model with boundedly rational investors, nuclear power typically dominates electricity production. We discuss implications of our modelling results for making a transition to low carbon electricity in the future.  相似文献   
92.
Isolation of cannabinoids from Cannabis and chemical production of synthetic cannabinoids resulted in understanding of their mechanism of action. Presently, renewed interest in therapeutic potential of cannabinoids is observed. There are numerous studies in the range of chemistry, pharmacology, and molecular biology that investigate the possibilities of their therapeutic application. This review presents results of research on cannabinoids with an emphasis on THC and its effect on a progression of selected diseases. The paper discusses previous reports and outlines future directions.  相似文献   
93.
Neuropilin-1 (NRP-1), the major co-receptor of vascular endothelial growth factor receptor-2 (VEGFR-2), may also independently act with VEGF-A165 to stimulate tumour growth and metastasis. Therefore, there is great interest in compounds that can block VEGF-A165/NRP-1 interaction. Peptidomimetic type inhibitors represent a promising strategy in the treatment of NRP-1-related disorders. Here, we present the synthesis, affinity, enzymatic stability, molecular modeling and in vitro binding evaluation of the branched urea–peptide hybrids, based on our previously reported Lys(hArg)-Dab-Oic-Arg active sequence, where the Lys(hArg) branching has been modified by introducing urea units to replace the peptide bond at various positions. One of the resulting hybrids increased the affinity of the compound for NRP-1 more than 10-fold, while simultaneously improving resistance for proteolytic stability in serum. In addition, ligand binding to NRP-1 induced rapid protein stock exocytotic trafficking to the plasma membrane in breast cancer cells. Examined properties characterize this compound as a good candidate for further development of VEGF165/NRP-1 inhibitors.  相似文献   
94.
比较从低品位电工电子废料中选择性回收铜的3种湿法冶金方法。首先将废料熔炼成Cu?Zn?Sn?Ag合金,并采用SEM?EDS和XRD进行表征。对合金进行阳极溶解,首先采用氨溶液和硫酸溶液对合金进行电沉积或在氨?硫酸铵溶液中浸出,然后进行电沉积铜。实现了各种金属分离,Pb、Ag 和Sn等沉积在阳极泥中,而铜则转移至电解液中并在阴极上还原析出。最佳的处理条件为在硫酸溶液中浸出,获得的最终产品为高纯Cu(99%),电流效率为90%。采用氨浸出可使Cu离子富集在电解液中,利于后续的电沉积,但是自发溶解的速率较低。在氨?硫酸铵溶液中进行阳极溶解不利于各种金属在阳极泥、电解液和阴极沉积物进行分离。  相似文献   
95.
The resistance of extractants to light is important during industrial extraction processes. A photodegradation of the organothiophosphorous extractant Cyanex 301 in toluene and hexane as organic diluent and the identification of possible degradation products using FT-IR and GC-MS techniques were performed. The influence of copper(II) and cobalt(II) ions on the stability of the extractant under UV-vis light exposure was also studied. The changes in the percentage composition of individual components of the extractant depended on the types of organic diluents and copper or cobalt ions. During this process, copper complex irradiation precipitation of black powder and photooxidation of toluene were observed. Based on these results we proposed a hypothetical mechanism of photodegradation of extractant Cyanex 301.  相似文献   
96.
97.
Nanocrystalline iron was obtained by fusing magnetite and promoters. The oxidized form was reduced with hydrogen and passivated (sample P0). The average nanocrystallite size in sample P0 was d(P0) =16 nm and the width of size distribution was σ(P0) = 18 nm. Samples of nanocrystalline iron with narrower diameter ranges and larger and smaller average crystallite sizes were also synthesized. They were: sample P1 (d(P1) = 28 nm, σ(P1) = 5 nm), sample P2 (d(P2) = 22 nm, σ(P1) = 5 nm), sample P3 (d(P3) = 12 nm, σ(P1) = 9 nm). These four samples were studied at room temperature by dc magnetization measurements and ferromagnetic resonance at microwave frequency. Correlations between samples sizes distributions (average size and width of the sizes) and magnetic parameters (effective magnetization, anisotropy field, anisotropy constant, FMR linewidth) were investigated. It was found that the anisotropy field and effective magnetization determined from FMR spectra scale linearly with nanoparticle sizes, while the effective magnetic anisotropy constant determined from the hysteresis loops decreases with nanoparticle size increase.  相似文献   
98.
We developed nanoparticles with tailored magnetic properties for direct and sensitive detection of biomolecules in biological samples in a single step. Thermally blocked nanoparticles obtained by thermal hydrolysis, functionalized with specific ligands, are mixed with sample solutions, and the variation of the magnetic relaxation due to surface binding is used to detect the presence of biomolecules. The binding significantly increases the hydrodynamic volume of nanoparticles, thus changing their Brownian relaxation frequency which is measured by a specifically developed AC susceptometer. The system was tested for the presence of Brucella antibodies, a dangerous pathogen causing brucellosis with severe effects both on humans and animals, in serum samples from infected cows and the surface of the nanoparticles was functionalized with lipopolysaccharides (LPS) from Brucella abortus. The hydrodynamic volume of LPS-functionalized particles increased by 25-35% as a result of the binding of the antibodies, measured by changes in the susceptibility in an alternating magnetic field. The method has shown high sensitivity, with detection limit of 0.05 microg x mL(-1) of antibody in the biological samples without any pretreatment. This magnetic-based assay is very sensitive, cost-efficient, and versatile, giving a direct indication whether the animal is infected or not, making it suitable for point-of-care applications. The functionalization of tailored magnetic nanoparticles can be modified to suit numerous homogeneous assays for a wide range of applications.  相似文献   
99.
A novel in situ synthesis of Pd nanoparticles supported in hollow carbon spheres (HCS) is reported. The size of the nanoparticles can be tuned via application of different Pd precursors. The hydrogen storage properties of Pd supported in HCS under room temperature were examined at partial pressures. We observed significant difference between the storage capacities of two samples containing Pd nanoparticles with different diameter distributions. The results showed that the sample with suitable diameters of Pd nanoparticles was more favorable for the H2 storage, even lower mass of Pd was used. The maximum hydrogen storage of 0.36 wt % exhibited the sample with Pd nanoparticles with the diameter of 11 nm (measured at 298 K and 24 bar) and it was enhanced by the factor of two in respect to the pristine HCS. The enhanced storage capacity is due to cumulative hydrogen adsorption by HCS and Pd nanoparticles. We also propose the mechanism of hydrogen storage in our material.  相似文献   
100.
The in vitro anticancer activity of the dinuclear trithiolato‐bridged arene ruthenium complex diruthenium‐1 (DiRu‐1) was evaluated against a panel of human cancer cell lines used as in vitro models for hepatocellular carcinoma (HepG2 cells), estrogen‐responsive breast adenocarcinoma (MCF‐7 cells), and triple‐negative breast adenocarcinoma (MDA‐MB‐231 cells). DiRu‐1 is highly cytotoxic to these cell lines, demonstrating half‐maximal inhibitory concentrations (IC50) in the low‐nanomolar range (77±1.4 to 268.2±4.4 nm ). The main molecular mechanisms responsible for the high cytotoxicity of DiRu‐1 against the most responsive MCF‐7 cell line (IC50=77±1.4 nm) were investigated on the basis of the capacity of DiRu‐1 to induce oxidative stress, apoptosis, and DNA damage, and to inhibit the cell cycle and proliferation. The results show that DiRu‐1 triggers caspase‐dependent apoptosis in MCF‐7 cells on both the intrinsic and extrinsic pathways. Moreover, the Ru complex also causes necrosis, mitotic catastrophe, and autophagy. DiRu‐1 increases the intracellular levels of reactive oxygen species (ROS), which play a significant role in its cytotoxicity and pro‐apoptotic activity. An important mechanism of the anticancer activity of DiRu‐1 appears to be the induction of DNA lesions, mainly due to apoptotic DNA fragmentation and cell‐cycle arrest at the G2/M checkpoint. These changes are correlated with the concentration of DiRu‐1, the duration of the cell treatment, and the post‐treatment time.  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-23

京公网安备 11010802026262号