全文获取类型
收费全文 | 1872篇 |
免费 | 212篇 |
国内免费 | 62篇 |
专业分类
电工技术 | 99篇 |
综合类 | 77篇 |
化学工业 | 381篇 |
金属工艺 | 58篇 |
机械仪表 | 74篇 |
建筑科学 | 100篇 |
矿业工程 | 36篇 |
能源动力 | 89篇 |
轻工业 | 156篇 |
水利工程 | 26篇 |
石油天然气 | 23篇 |
武器工业 | 15篇 |
无线电 | 228篇 |
一般工业技术 | 366篇 |
冶金工业 | 94篇 |
原子能技术 | 18篇 |
自动化技术 | 306篇 |
出版年
2024年 | 8篇 |
2023年 | 53篇 |
2022年 | 114篇 |
2021年 | 169篇 |
2020年 | 119篇 |
2019年 | 101篇 |
2018年 | 99篇 |
2017年 | 94篇 |
2016年 | 86篇 |
2015年 | 98篇 |
2014年 | 116篇 |
2013年 | 154篇 |
2012年 | 122篇 |
2011年 | 135篇 |
2010年 | 70篇 |
2009年 | 68篇 |
2008年 | 68篇 |
2007年 | 62篇 |
2006年 | 62篇 |
2005年 | 47篇 |
2004年 | 39篇 |
2003年 | 31篇 |
2002年 | 38篇 |
2001年 | 25篇 |
2000年 | 19篇 |
1999年 | 18篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有2146条查询结果,搜索用时 156 毫秒
1.
Kumar Kuila Saikat Kumbhakar Partha Sekhar Tiwary Chandra Kumar Kundu Tarun 《Journal of Materials Science》2022,57(19):8658-8675
Journal of Materials Science - Hybrid oxidation methodologies (HOMs) and active site enrichment of 2D nanocatalyst through defects induction are ubiquitously used for generating adequate reactive... 相似文献
2.
Kalli Sai Bhavani Tummala Anusha Pradeep Kumar Brahman 《International Journal of Hydrogen Energy》2021,46(13):9199-9214
In the present study, we report an eco-friendly and simple route to design and synthesize novel nanocomposite catalyst based on platinum nanoparticles anchored on binary support of graphitic carbon nitride (g-C3N4) and cobalt-metal-organic framework (ZIF-67). For this purpose, ZIF-67 was prepared by precipitation method and g-C3N4 was prepared through thermal polymerization method. Later, ZIF-67 and g-C3N4 were hybridized through sonication to get homogeneous g–C3N4–ZIF-67 nanocomposite support material. Platinum nanoparticles (PtNPs) were uniformly deposited on g–C3N4–ZIF-67 by an electrochemical method. The as-developed nanocatalyst was characterized by morphological, structural and electrochemical techniques. The electrocatalytic activity of PtNPs@g–C3N4–ZIF-67 nanocatalyst towards butanol oxidation was evaluated via CV, CA, LSV and EIS in an alkaline medium. Results revealed that the proposed catalyst showed greatly enhanced electrooxidation of butanol in terms of high magnificent current density, lower oxidation potential, excellent long-term stability, large surface area, low charge transfer resistance and less toxic ability. Enhanced catalytic performance of the proposed catalyst could be ascribed to the synergistic effect of g–C3N4–ZIF-67 nanocomposite and PtNPs. The PtNPs@g–C3N4–ZIF-67 catalyst holds promising potential applications to be used as an anodic electrocatalyst for the development of high-performance alkaline fuel cells. 相似文献
3.
4.
5.
Mandal Tarun K.; Mukhopadhyay Chaitali 《Protein engineering, design & selection : PEDS》2002,15(12):979-986
Galectins show remarkable binding specificity towards ß-galactosides.A recently developed method for calculating binding free energiesbetween a protein and its substrates has been used to evaluatethe binding specificity of galectin-3. Five disaccharides anda tetrasaccharide were used as the substrates. The calculatedbinding free energies agree quite well with the experimentaldata and the ranking of binding affinities is well reproduced.For all the six proteinligand complexes it was observedthat electrostatic interactions oppose binding whereas the non-polarcontributions drive complex formation. The observed bindingspecificity of galectin-3 for galactosides rather than glucosidesis discussed in light of our results. 相似文献
6.
Applying the critical path method to manufacturing routing 总被引:1,自引:0,他引:1
Traditionally the critical path method (CPM) has been used primarily as an a'priori planning and scheduling device. Its applications have typically been limited to one-shot projects, usually with a long period of completion time. This paper proposes taking these ideas to continuous production systems, and to implement the CPM not just at the outset but throughout the process. The algorithm calls for repeatedly calculating the critical path through the production process and routing parts so as to remain off this path. Before the model is presented, some basic ideas are introduced from group technology (GT) and CPM. After the presentation of the model, two potential implementations with the usage of computer are proposed. 相似文献
7.
I Tamai T Nakanishi K Hayashi T Terao Y Sai T Shiraga K Miyamoto E Takeda H Higashida A Tsuji 《Canadian Metallurgical Quarterly》1997,49(8):796-801
Although recent evidence suggests that certain beta-lactam antibiotics are absorbed via a specific transport mechanism, its nature is unclear. To confirm whether peptide transport in the rat can be largely ascribed to the intestinal oligopeptide transporter PepT1, the transporter has been functionally characterized and its significance in the intestinal absorption of beta-lactam antibiotics was evaluated. For evaluation of transport activity complementary RNA (cRNA) of rat PepT1 was synthesized in-vitro and expressed in Xenopus laevis oocytes. cRNA induced uptake of several beta-lactam antibiotics and the dipeptide [14C]glycylsarcosine; this was specifically inhibited by various dipeptides and tripeptides but not by their constituent amino acids or by tetra- or pentapeptides. The transport activity of PepT1 for beta-lactam antibiotics correlated well with their in-vivo intestinal transport and absorption. Furthermore, mutual inhibitory effects on uptake were observed between glyclsarcosine and beta-lactam antibiotics. Hybrid depletion of the functional expression of rat PepT1 in oocytes injected with rat intestinal epithelial total mRNA was studied using an antisense oligonucleotide corresponding to the 5'-coding region of PepT1. In oocytes injected with rat mRNA pre-hybridized with the antisense oligonucleotide against rat PepT1, the uptake of [14C]glycylsarcosine was almost completely abolished, whereas its uptake was not influenced by a sense oligonucleotide for the same region of PepT1. Similarly, the uptake of beta-lactam antibiotics was also reduced by the antisense oligonucleotide against rat PepT1. These results demonstrate that the intestinal proton-coupled oligopeptide transporter PepT1 plays a predominant role in the carrier-mediated intestinal absorption of beta-lactam antibiotics and native oligopeptides in the rat. 相似文献
8.
Characterizing the impact of variability on circuit performance measurements (delay, power, and signal integrity) is necessary to avoid chip failure. The authors present a comprehensive methodology for analyzing the impact of device and metal variations on the power supply noise, and hence the signal integrity, of on-chip power grids. 相似文献
9.
The increasing need to instruct students in the use of personal computer software, especially electronic spreadsheets, is placing greater demands on the already full university curriculum. A potential help in meeting these demands is the readily available computer-based software tutorials. In order to explore the feasibility of computer-based instruction as an alternative to human instruction, this research compares two modes of instruction, computer-based and human. An experiment was conducted with groups of business student subjects. The research results indicate no difference in students' attitude towards computer-based instruction and human instruction of spreadsheets. Students' short-term recall of the software syntax being taught is as strong with computer-based instruction as with human instruction. These results were not affected by the level of personal computer experience that students had prior to the experiment. However, the ability to comprehend and immediately apply the software to a task is greater with human instruction than with computer-aided instruction. This advantage holds true for students instructed by experienced and inexperienced instructors. 相似文献
10.
Axial bed depth profiles were experimentally measured in a rotary kiln containing ilmenite particles under steady state and transient conditions. The variables include feed rate of solids, inclination and rotational speed of the kiln. and dam height. The variation of the axial velocity with kiln axis was estimated. The semi-experimental model proposed by Perron and Bui (1990) was modified to include the effect of the variables of the present study. The mean residence time of solids was estimated from the fractional hold-up and expressed in terms of the process variables. The transients induced by a step change in any of the operating conditions were measured as variation of discharge rate of solids with time. 相似文献