全文获取类型
收费全文 | 3979篇 |
免费 | 128篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 34篇 |
综合类 | 5篇 |
化学工业 | 820篇 |
金属工艺 | 112篇 |
机械仪表 | 83篇 |
建筑科学 | 91篇 |
矿业工程 | 8篇 |
能源动力 | 126篇 |
轻工业 | 148篇 |
水利工程 | 18篇 |
石油天然气 | 19篇 |
无线电 | 385篇 |
一般工业技术 | 925篇 |
冶金工业 | 744篇 |
原子能技术 | 33篇 |
自动化技术 | 573篇 |
出版年
2023年 | 24篇 |
2022年 | 44篇 |
2021年 | 72篇 |
2020年 | 60篇 |
2019年 | 55篇 |
2018年 | 80篇 |
2017年 | 65篇 |
2016年 | 85篇 |
2015年 | 63篇 |
2014年 | 86篇 |
2013年 | 218篇 |
2012年 | 134篇 |
2011年 | 173篇 |
2010年 | 156篇 |
2009年 | 178篇 |
2008年 | 155篇 |
2007年 | 160篇 |
2006年 | 126篇 |
2005年 | 114篇 |
2004年 | 133篇 |
2003年 | 101篇 |
2002年 | 102篇 |
2001年 | 90篇 |
2000年 | 91篇 |
1999年 | 92篇 |
1998年 | 140篇 |
1997年 | 108篇 |
1996年 | 97篇 |
1995年 | 71篇 |
1994年 | 80篇 |
1993年 | 78篇 |
1992年 | 78篇 |
1991年 | 66篇 |
1990年 | 56篇 |
1989年 | 61篇 |
1988年 | 48篇 |
1987年 | 41篇 |
1986年 | 42篇 |
1985年 | 51篇 |
1984年 | 48篇 |
1983年 | 45篇 |
1982年 | 30篇 |
1981年 | 33篇 |
1980年 | 35篇 |
1979年 | 22篇 |
1978年 | 23篇 |
1977年 | 33篇 |
1976年 | 40篇 |
1974年 | 21篇 |
1973年 | 26篇 |
排序方式: 共有4124条查询结果,搜索用时 15 毫秒
101.
Tianjiao Jia Yang Wang Yuanyuan Dou Yaowang Li Monica Jung de Andrade Run Wang Shaoli Fang Jingjing Li Zhou Yu Rui Qiao Zhuangjian Liu Yuan Cheng Yewang Su Majid Minary‐Jolandan Ray H. Baughman Dong Qian Zunfeng Liu 《Advanced functional materials》2019,29(18)
Smart textiles that sense, interact, and adapt to environmental stimuli have provided exciting new opportunities for a variety of applications. However, current advances have largely remained at the research stage due to the high cost, complexity of manufacturing, and uncomfortableness of environment‐sensitive materials. In contrast, natural textile materials are more attractive for smart textiles due to their merits in terms of low cost and comfortability. Here, water fog and humidity‐driven torsional and tensile actuation of thermally set twisted, coiled, plied silk fibers, and weave textiles from these silk fibers are reported. When exposed to water fog, the torsional silk fiber provides a fully reversible torsional stroke of 547° mm?1. Coiled‐and‐thermoset silk yarns provide a 70% contraction when the relative humidity is changed from 20% to 80%. Such an excellent actuation behavior originates from water absorption‐induced loss of hydrogen bonds within the silk proteins and the associated structural transformation, which are corroborated by atomistic and macroscopic characterization of silk and molecular dynamics simulations. With its large abundance, cost‐effectiveness, and comfortability for wearing, the silk muscles will open up additional possibilities in industrial applications, such as smart textiles and soft robotics. 相似文献
102.
Jason K. Iles Raminta Zmuidinaite Christoph Sadee Anna Gardiner Jonathan Lacey Stephen Harding Gregg Wallis Roshani Patel Debra Roblett Jonathan Heeney Helen Baxendale Ray Kruse Iles 《International journal of molecular sciences》2022,23(11)
The involvement of immunoglobulin (Ig) G3 in the humoral immune response to SARS-CoV-2 infection has been implicated in the pathogenesis of acute respiratory distress syndrome (ARDS) in COVID-19. The exact molecular mechanism is unknown, but it is thought to involve this IgG subtype’s differential ability to fix, complement and stimulate cytokine release. We examined the binding of convalescent patient antibodies to immobilized nucleocapsids and spike proteins by matrix-assisted laser desorption/ionization–time of flight (MALDI-ToF) mass spectrometry. IgG3 was a major immunoglobulin found in all samples. Differential analysis of the spectral signatures found for the nucleocapsid versus the spike protein demonstrated that the predominant humoral immune response to the nucleocapsid was IgG3, whilst for the spike protein it was IgG1. However, the spike protein displayed a strong affinity for IgG3 itself, as it would bind from control plasma samples, as well as from those previously infected with SARS-CoV-2, similar to the way protein G binds IgG1. Furthermore, detailed spectral analysis indicated that a mass shift consistent with hyper-glycosylation or glycation was a characteristic of the IgG3 captured by the spike protein. 相似文献
103.
Chinmay Rao Asok Ray Soumik Sarkar Murat Yasar 《Signal, Image and Video Processing》2009,3(2):101-114
Symbolic dynamic filtering (SDF) has been recently reported in literature as a pattern recognition tool for early detection
of anomalies (i.e., deviations from the nominal behavior) in complex dynamical systems. This paper presents a review of SDF
and its performance evaluation relative to other classes of pattern recognition tools, such as Bayesian Filters and Artificial
Neural Networks, from the perspectives of: (i) anomaly detection capability, (ii) decision making for failure mitigation and
(iii) computational efficiency. The evaluation is based on analysis of time series data generated from a nonlinear active
electronic system.
This work has been supported in part by the U.S. Army Research Laboratory and the U.S. Army Research Office under Grant No.
W911NF-07-1-0376, by the U.S. Office of Naval Research under Grant No. N00014-08-1-380, and by NASA under Cooperative Agreement
No. NNX07AK49A. 相似文献
104.
Yi Feng Shaon Borosha Anamika Ratri Eun Bee Lee Huizhen Wang Timothy A. Fields William H. Kinsey Jay L. Vivian M. A. Karim Rumi Patrick E. Fields 《International journal of molecular sciences》2022,23(9)
Erythropoietin (EPO) signaling plays a vital role in erythropoiesis by regulating proliferation and lineage-specific differentiation of murine hematopoietic progenitor cells (HPCs). An important downstream response of EPO signaling is calcium (Ca2+) influx, which is regulated by transient receptor potential channel (TRPC) proteins, particularly TRPC2 and TRPC6. While EPO induces Ca2+ influx through TRPC2, TRPC6 inhibits the function of TRPC2. Thus, interactions between TRPC2 and TRPC6 regulate the rate of Ca2+ influx in EPO-induced erythropoiesis. In this study, we observed that the expression of TRPC6 in KIT-positive erythroid progenitor cells was regulated by DOT1L. DOT1L is a methyltransferase that plays an important role in many biological processes during embryonic development including early erythropoiesis. We previously reported that Dot1l knockout (Dot1lKO) HPCs in the yolk sac failed to develop properly, which resulted in lethal anemia. In this study, we detected a marked downregulation of Trpc6 gene expression in Dot1lKO progenitor cells in the yolk sac compared to the wild type (WT). The promoter and the proximal regions of the Trpc6 gene locus exhibited an enrichment of H3K79 methylation, which is mediated solely by DOT1L. However, the expression of Trpc2, the positive regulator of Ca2+ influx, remained unchanged, resulting in an increased TRPC2/TRPC6 ratio. As the loss of DOT1L decreased TRPC6, which inhibited Ca2+ influx by TRPC2, Dot1lKO HPCs in the yolk sac exhibited accelerated and sustained elevated levels of Ca2+ influx. Such heightened Ca2+ levels might have detrimental effects on the growth and proliferation of HPCs in response to EPO. 相似文献
105.
Ray Lara A.; Miranda Robert Jr.; MacKillop James; McGeary John; Tidey Jennifer W.; Rohsenow Damaris J.; Gwaltney Chad; Swift Robert W.; Monti Peter M. 《Canadian Metallurgical Quarterly》2009,17(2):122
Topiramate, an anticonvulsant medication, is an efficacious treatment for alcohol dependence. To date, little is known about genetic moderators of side effects from topiramate. The objective of this study was to examine 3 single nucleotide polymorphisms (SNPs) of the glutamate receptor GluR5 gene (GRIK1) as predictors of topiramate-induced side effects in the context of a laboratory study of topiramate. Heavy drinkers (n = 51, 19 women and 32 men), 75% of whom met criteria for an alcohol use disorder, completed a 5-week dose escalation schedule to a target dose of either 200 or 300 mg or matched placebo. The combined medication groups were compared with placebo-treated individuals for side effects at target dose. Analyses revealed that an SNP in intron 9 of the GRIK1 gene (rs2832407) was associated with the severity of topiramate-induced side effects and with serum levels of topiramate. Genes underlying glutamatergic neurotransmission, such as the GRIK1 gene, may help predict heterogeneity in topiramate-induced side effects. Future studies in larger samples are needed to more fully establish these preliminary findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Kenneth J. Kokjer Katrina A. Ray‐Landis Robert A. Dieterich 《The International journal of environmental studies》2013,70(2-3):103-113
A portable computer system is described which supports timely data management for reindeer herding. An initial version has been in use for two years, supporting research on reindeer diseases. Versions are being developed which will expand the system to support commercial herd management. The hardware system is integrated from commercially available equipment. The software is currently composed of a set of ten programs, with others under development for enhancements and modifications. At field roundups, the computer allows new animals to be added to the data base plus rapid access to information on existing individual animals. Historical information can be displayed, including detailed historical records of reproductive activity, medical treatments, serological exam results, and observations of anomalies (e.g. infections, injuries, etc.). In the field, or in the lab, the data base may be accessed for information on specific animals and for summaries of herd data. 相似文献
107.
German regulations for the thermal renovation of existing homes demand high thermal standards, which the government claims are technically and economically feasible. This paper examines existing data on 3400 German homes; their calculated energy performance ratings (EPR) are then plotted against the actual measured consumption. The results indicate that occupants consume, on average, 30% less heating energy than the calculated rating. This phenomenon is identified as the ‘prebound’ effect and increases with the calculated rating. The opposite phenomenon, the rebound effect, tends to occur for low-energy dwellings, where occupants consume more than the rating. A similar phenomenon has been recognized in recent Dutch, Belgian, French and UK studies, suggesting policy implications in two directions. Firstly, using a dwelling's energy rating to predict fuel and CO2 savings through retrofits tends to overestimate savings, underestimate the payback time and possibly discourage cost-effective, incremental improvements. Secondly, the potential fuel and CO2 savings through non-technical measures such as occupant behaviour may well be far larger than is generally assumed in policies so policy-makers need a better understanding of what drives or inhibits occupants' decisions. La réglementation allemande relative à la rénovation thermique des logements existants exige des normes thermiques élevées, que le gouvernement prétend être techniquement et économiquement applicables. Cet article examine les données existantes sur 3400 logements allemands; leurs classes d'efficacité énergétique (CEE) calculées sont ensuite comparées à la consommation réelle mesurée. Les résultats indiquent que les occupants consomment, en moyenne, 30 % d'énergie de chauffage en moins que la classe calculée. Ce phénomène est identifié en raison de l'accroissement de l'effet de « pré-bond » avec la classe calculée. Le phénomène opposé, l'effet de rebond, tend à se produire dans les logements à basse consommation d'énergie, dans lesquels les occupants ont une consommation supérieure à la classe. Un phénomène similaire a été reconnu dans des études récentes néerlandaises, belges, françaises et britanniques, suggérant des implications en termes de politiques dans deux directions. En premier lieu, l'utilisation de la classe énergétique d'un logement pour prévoir les économies de combustible et de CO2 pouvant être obtenues grâce à des rénovations a tendance à surestimer les économies, à sous-estimer le délai d'amortissement et éventuellement à dissuader d'effectuer des améliorations incrémentielles rentables. En second lieu, les économies potentielles de combustible et de CO2 pouvant être obtenues par des mesures non techniques telles que le comportement des occupants peuvent se révéler être bien plus importantes que cela n'est supposé en règle générale dans les politiques, de sorte que les décideurs ont besoin de mieux comprendre ce qui motive ou empêche les décisions des occupants. Mots clés: performance des bâtiments, rénovations thermiques, politique climatique, classe énergétique, politique énergétique, comportement de consommation énergétique 相似文献
108.
Senggam Wakhet S. S. Sagiri S. S. Ray Arfat Anis 《Polymer-Plastics Technology and Engineering》2016,55(5):530-541
The present study describes the encapsulation of vegetable fats (cocoa butter and mango butter) within chitosan microparticles by double emulsion technique to prevent leaching of the internal apolar phase. Leaching studies suggested negligible leaching of the internal phase (~12–14%) when the fats were encapsulated as compared to the control (~40%). Fourier transform infrared spectroscopy and differential scanning calorimeter studies confirmed the successful encapsulation of fats. The release of drug (ciprofloxacin) from the microparticles was diffusion and erosion mediated and were capable to elicit antimicrobial activity against Escherichia coli. The study suggests that the developed microparticles have the potential for controlled delivery of antimicrobials. 相似文献
109.
Morphology and thermal properties of recycled polyacrylonitrile fiber blends with poly(ethylene terephthalate): Microstructural characterization 下载免费PDF全文
The compounding of rPAN/PET [polyacrylonitrile/poly(ethylene terephthalate]; 30/70, 50/50, and 70/30 wt %) using a melt‐blending technique was the main focus of this investigation. An X‐ray diffraction study indicated the possibility of interphase boundary interactions between the polymer matrices in the blends. The differential scanning calorimetry results showed that varying the ratios of rPAN in the blends marginally improved the processing temperature of PET. The thermogravimetric analysis revealed that the addition of PET up to 70% increased the thermal stability of the blend, and adding more than 70% of PET resulted in poor adhesion between the matrix and phase. On the basis of the results obtained, we propose a general understanding of how the morphology and the mechanical and thermal properties of the blend could assist in the development of rPAN blends with PET, rather than disposing of the viable materials as wastes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43777. 相似文献
110.