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   264篇
  免费   15篇
电工技术   3篇
化学工业   73篇
金属工艺   2篇
机械仪表   3篇
建筑科学   8篇
矿业工程   2篇
能源动力   10篇
轻工业   38篇
水利工程   3篇
无线电   19篇
一般工业技术   41篇
冶金工业   27篇
自动化技术   50篇
  2023年   6篇
  2022年   11篇
  2021年   23篇
  2020年   10篇
  2019年   13篇
  2018年   8篇
  2017年   8篇
  2016年   10篇
  2015年   11篇
  2014年   11篇
  2013年   15篇
  2012年   14篇
  2011年   18篇
  2010年   12篇
  2009年   16篇
  2008年   15篇
  2007年   8篇
  2006年   7篇
  2005年   9篇
  2004年   10篇
  2003年   7篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   4篇
  1985年   2篇
  1983年   2篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1966年   1篇
  1961年   1篇
排序方式: 共有279条查询结果,搜索用时 31 毫秒
71.
Ohne Zusammenfassung This article is also available in English via and : Winter R, Baskerville R (2009) BISE – Call for Papers, Issue 5/2010, Science of Business and Information Systems Engineering. Bus Inf Syst Eng. doi: 10.1007/s12599-009-0047-2.  相似文献   
72.
Context-awareness constitutes an essential aspect of services, especially when interaction with end-users is involved. In this paper a solution for the context-aware development of web applications consisting of web services is presented. The methodology proposes a model based approach and advocates in favour of a complete separation of the web application functionality from the context adaptation at all development phases (analysis, design, implementation). In essence, context adaptation takes place on top of and is transparent to the web application business functionality. Starting from UML diagrams of independent web services and respective UML context models, our approach can produce a functional composite context-aware application. At execution level this independence is maintained through an adaptation framework based on message interception.  相似文献   
73.
Difference gel electrophoresis enables the accurate quantification of changes in the proteome including combinations of PTMs and protein isoform expression. Here, we review recent advances in study design, image acquisition, and statistical analysis. We also compare DIGE to established and emerging mass spectrometric analysis technologies. Despite these recent advances in MS and the still unsolved limitations of 2DE to map hydrophobic, high molecular weight proteins with extreme pIs, DIGE remains the most comprehensive top-down method to study changes in abundance of intact proteins.  相似文献   
74.
Functional verification is “the” major design-phase bottleneck for silicon productivity. Since functional verification is an NP-complete problem, it relies on a large number of heuristics with associated parameters (engines). With the advent of parallel processing, formal verification can be optimized by selecting the best n engines to run in parallel, increasing the chance of reaching successful termination of the verification task. In this paper, we will present a methodology to build engine estimators based on structural metrics and to select n engines to run in parallel. The methodology considers both engines’ estimated performance and engines’ correlation. Results confirmed that the methodology can be a very quick selection mechanism for parallelization of engines in order to increase the chance of running the best engines to solve the problem.  相似文献   
75.
On the stabilization of feedforward systems with bounded control   总被引:2,自引:0,他引:2  
For the global asymptotic stabilization of nonlinear—controllable in the first approximation—cascades consisting of a globally asymptotically—locally exponentially stable system driving a stable system, a Lyapunov-like design is proposed. This yields (bounded) control laws, where the control magnitude can be chosen arbitrarily large. This result provides an alternative to classical forwarding.  相似文献   
76.
A polymer‐bound reagent for the efficient oxidation of primary alcohols to aldehydes and secondary alcohols to ketones in the presence of a catalytic amount of 2,2,6,6‐tetramethyl‐1‐piperidinyloxyl (TEMPO) is described. The oxidation process is particular mild and allows one to prepare aldehydes with α‐chirality without racemization. This also includes the synthesis of α‐aminoaldehydes. In most cases, work‐up of this heavy metal‐free oxidation is achieved by simple filtration followed by removal of the solvent. Insight into the role of the bromate(I) anion in the oxidation process was gained from the TEMPO‐mediated oxidation of benzaldehyde in the presence of the hypochlorite anion loaded on an anion exchange resin.  相似文献   
77.
Social and spatial network analysis is an important approach for investigating infectious disease transmission, especially for pathogens transmitted directly between individuals or via environmental reservoirs. Given the diversity of ways to construct networks, however, it remains unclear how well networks constructed from different data types effectively capture transmission potential. We used empirical networks from a population in rural Madagascar to compare social network survey and spatial data-based networks of the same individuals. Close contact and environmental pathogen transmission pathways were modelled with the spatial data. We found that naming social partners during the surveys predicted higher close-contact rates and the proportion of environmental overlap on the spatial data-based networks. The spatial networks captured many strong and weak connections that were missed using social network surveys alone. Across networks, we found weak correlations among centrality measures (a proxy for superspreading potential). We conclude that social network surveys provide important scaffolding for understanding disease transmission pathways but miss contact-specific heterogeneities revealed by spatial data. Our analyses also highlight that the superspreading potential of individuals may vary across transmission modes. We provide detailed methods to construct networks for close-contact transmission pathogens when not all individuals simultaneously wear GPS trackers.  相似文献   
78.
Lactobacillus fermentum ACA-DC 179, Lactobacillus plantarum ACA-DC 287 and Streptococcus macedonicus ACA-DC 198 were studied for their probiotic potential. Firstly, strains were screened for antimicrobial activity towards a broad range of target strains, including lactic acid bacteria, food spoilage and pathogenic bacteria. L. fermentum ACA-DC 179 was active against five streptococci, including the two pathogenic strains Streptococcus oralis LMG 14532T and Streptococcus pneumoniae LMG 14545T. S. macedonicus ACA-DC 198 was active against the majority of the strains tested, including not only lactic acid bacteria but also many food spoilage or pathogenic species. The three potential probiotic strains were found to survive variably at pH 2.5 and were unaffected by bile salts. Only S. macedonicus ACA-DC 198 exhibited bile salt hydrolase activity, while none of the strains was haemolytic. Moreover, strains exhibited variable susceptibility towards commonly used antibiotics. L. plantarum ACA-DC 287 and S. macedonicus ACA-DC 198 induced the secretion of the pro-inflammatory cytokines IL-12, IFN-gamma and TNF-alpha by human peripheral blood mononuclear cells. Also elevated levels of the anti-inflammatory IL-10 were observed with L. fermentum ACA-DC 179. This strain consequently was found to significantly reduce colitis in a TNBS-induced colitis mouse model. Furthermore, L. fermentum ACA-DC 179 was successfully applied in an experimental Salmonella-infection mouse model. To conclude, strain L. fermentum ACA-DC 179 possesses desirable probiotic properties, such as antimicrobial activity and immunomodulation in vitro, which were confirmed in vivo by the use of animal models.  相似文献   
79.
Glutathione S-transferases (GSTs) are a heterogeneous family of enzymes that catalyse the conjugation of glutathione (GSH) to electrophilic sites on a variety of hydrophobic substrates. In the present study three amino acid residues (Trp12, Phe35 and Ile118) of the xenobiotic binding site (H-site) of maize GST I were altered in order to evaluate their contribution to substrate binding and catalysis. These residues are not conserved and hence may affect substrate specificity and/or product dissociation. The results demonstrate that these residues are important structural moieties that modulate an enzyme's catalytic efficiency and specificity. Phe35 and Ile118 also participate in k(cat) regulation by affecting the rate-limiting step of the catalytic reaction. The effect of temperature on the catalytic activity of the wild-type and mutant enzymes was also investigated. Biphasic Arrhenius and Eyring plots for the wild-type enzyme showed an apparent transition temperature at 35 degrees C, which seems to be the result of a change in the rate-limiting step of the catalytic reaction. Thermodynamic analysis of the activity data showed that the activation energy increases at low temperatures, whereas the entropy change seems to be the main determinant that contributes to the rate-limiting step at high temperatures.  相似文献   
80.
The occurrence of five endocrine-disrupting compounds (EDCs), namely 4-n-nonylphenol (4-n-NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), triclosan (TCS) and bisphenol A (BPA), was assessed in the raw, treated wastewater and sewage sludge of eight sewage treatment plants (STPs) in Greece. The analytes were extracted by solid-phase extraction (dissolved phase) or sonication (solid phase). Qualitative and quantitative analyses were performed by gas chromatography-mass spectrometry (GC-MS). The average concentrations in the raw and treated wastewater ranged from 0.23 (4-n-NP) to 5.76microgL(-1) (NP1EO) and from 0.15 (BPA) to 1.84microgL(-1) (NP2EO), respectively. A great part of the detected EDCs was sorbed on suspended solids. In sewage sludge, the average concentrations ranged between 0.17 (4-n-NP) and 12.3microgg(-1)dw (NP1EO). Analysis of daily mass flows in STP of Athens showed that, with the exception of 4-n-NP, all other EDCs were significantly removed (>85%) during wastewater treatment. Regarding the fate of these compounds, a significant part ranging from 45% (for TCS) to more than 70% (for NP1EO, NP2EO and BPA) was transformed by abiotic or biotic mechanisms, while the rest was accumulated in sewage sludge or disposed to the environment via the effluents. Calculation of risk quotients showed the existence of possible threat due to the presence of certain EDCs in treated wastewater and sludge.  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