全文获取类型
收费全文 | 11800篇 |
免费 | 380篇 |
国内免费 | 202篇 |
专业分类
电工技术 | 279篇 |
综合类 | 252篇 |
化学工业 | 1302篇 |
金属工艺 | 307篇 |
机械仪表 | 472篇 |
建筑科学 | 452篇 |
矿业工程 | 141篇 |
能源动力 | 186篇 |
轻工业 | 1158篇 |
水利工程 | 293篇 |
石油天然气 | 113篇 |
武器工业 | 74篇 |
无线电 | 1107篇 |
一般工业技术 | 1241篇 |
冶金工业 | 3751篇 |
原子能技术 | 163篇 |
自动化技术 | 1091篇 |
出版年
2022年 | 128篇 |
2021年 | 184篇 |
2020年 | 135篇 |
2019年 | 129篇 |
2018年 | 131篇 |
2017年 | 156篇 |
2016年 | 145篇 |
2015年 | 190篇 |
2014年 | 289篇 |
2013年 | 522篇 |
2012年 | 405篇 |
2011年 | 483篇 |
2010年 | 407篇 |
2009年 | 445篇 |
2008年 | 452篇 |
2007年 | 453篇 |
2006年 | 394篇 |
2005年 | 350篇 |
2004年 | 271篇 |
2003年 | 277篇 |
2002年 | 278篇 |
2001年 | 226篇 |
2000年 | 198篇 |
1999年 | 242篇 |
1998年 | 884篇 |
1997年 | 568篇 |
1996年 | 484篇 |
1995年 | 323篇 |
1994年 | 271篇 |
1993年 | 284篇 |
1992年 | 117篇 |
1991年 | 133篇 |
1990年 | 140篇 |
1989年 | 140篇 |
1988年 | 139篇 |
1987年 | 140篇 |
1986年 | 117篇 |
1985年 | 130篇 |
1984年 | 96篇 |
1983年 | 104篇 |
1982年 | 72篇 |
1981年 | 93篇 |
1980年 | 74篇 |
1979年 | 81篇 |
1978年 | 72篇 |
1977年 | 126篇 |
1976年 | 232篇 |
1975年 | 73篇 |
1974年 | 71篇 |
1973年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
152.
153.
Targeted Nanoparticle Thermometry: A Method to Measure Local Temperature at the Nanoscale Point Where Water Vapor Nucleation Occurs 下载免费PDF全文
Arwa A. Alaulamie Susil Baral Samuel C. Johnson Hugh H. Richardson 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(1)
An optical nanothermometer technique based on laser trapping, moving and targeted attaching an erbium oxide nanoparticle cluster is developed to measure the local temperature. The authors apply this new nanoscale temperature measuring technique (limited by the size of the nanoparticles) to measure the temperature of vapor nucleation in water. Vapor nucleation is observed after superheating water above the boiling point for degassed and nondegassed water. The average nucleation temperature for water without gas is 560 K but this temperature is lowered by 100 K when gas is introduced into the water. The authors are able to measure the temperature inside the bubble during bubble formation and find that the temperature inside the bubble spikes to over 1000 K because the heat source (optically‐heated nanorods) is no longer connected to liquid water and heat dissipation is greatly reduced. 相似文献
154.
Formal Specification and Quantitative Analysis of a Constellation of Navigation Satellites 下载免费PDF全文
Zhaoguang Peng Yu Lu Alice Miller Tingdi Zhao Chris Johnson 《Quality and Reliability Engineering International》2016,32(2):345-361
Navigation satellites are a core component of navigation satellite‐based systems such as Global Positioning System, Global Navigation Satellite System and Galileo, which provide location and timing information for a variety of uses. Such satellites are designed for operating on orbit to perform tasks and have lifetimes of 10 years or more. Reliability, availability and maintainability analysis of systems has been indispensable in the design phase of satellites in order to achieve minimum failures or to increase mean time between failures and thus to plan maintenance strategies, optimise reliability and maximise availability. In this paper, we present formal models of both a single satellite and a navigation satellite constellation and logical specification of their reliability, availability and maintainability properties, respectively. The probabilistic model checker PRISM has been used to perform automated analysis of these quantitative properties. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
155.
Lili Gong Qi Zhang Liangjun Wang Jianfeng Wu Cheng Han Bo Lei Wei Chen Goki Eda Kuan Eng Johnson Goh Chorng Haur Sow 《Nano Research》2018,11(9):4574-4586
We demonstrate a facile and effective approach to significantly improve the photoluminescence of bulk MoS2 via laser thinning followed by gold particle decoration. Upon laser thinning of exfoliated bulk MoS2, photoluminescence emerges from the laser-thinned region. After further treatment with an AuCl3 solution, gold particles self-assemble on the laser-thinned region and thick edges, further increasing the fluorescence of bulk MoS2 28 times and the Raman response 3 times. Such fluorescence enhancement can be attributed to both surface plasmon resonance and p-type doping induced by gold particles. The combination of laser thinning and AuCl3 treatment enables the functionalization of bulk MoS2 for optoelectronic applications. It can also provide a viable strategy for mask-free and area-selective p-type doping on single MoS2 flakes. 相似文献
156.
JD Kasprzak WB Vletter JR Roelandt JR van Meegen R Johnson FJ Ten Cate 《Canadian Metallurgical Quarterly》1998,40(2):314-321
To investigate possible biochemical mechanisms underlying the "toxic gain of function" associated with polyglutamine expansions, the ability of guinea pig liver tissue transglutaminase to catalyze covalent attachments of various polyamines to polyglutamine peptides was examined. Of the polyamines tested, spermine is the most active substrate, followed by spermidine and putrescine. Formation of covalent cross links between polyglutamine peptides and polyamines yields high-M(r) aggregates--a process that is favored with longer polyglutamines. In the presence of tissue transglutaminase, purified glyceraldehyde-3-phosphate dehydrogenase (a key glycolytic enzyme that binds tightly to the polyglutamine domains of both huntingtin and dentatorubral-pallidoluysian atrophy proteins) is covalently attached to polyglutamine peptides in vitro, resulting in the formation of high-M(r) aggregates. In addition, endogenous glyceraldehyde-3-phosphate dehydrogenase of a Balb-c 3T3 fibroblast cell line overexpressing human tissue transglutaminase forms cross-links with a Q60 polypeptide added to the cell homogenate. Possibly, expansion of polyglutamine domains (thus far known to occur in the gene products associated with at least seven neurodegenerative diseases) leads to increased/aberrant tissue transglutaminase-catalyzed cross-linking reactions with both polyamines and susceptible proteins, such as glyceraldehyde-3-phosphate dehydrogenase. Formation of cross-linked heteropolymers may lead to deposition of high-M(r) protein aggregates, thereby contributing to cell death. 相似文献
157.
DI Blyth MS Pedrick TJ Savage H Bright JE Beesley S Sanjar 《Canadian Metallurgical Quarterly》1998,19(1):38-54
158.
EO Johnson MB van den Bree AE Gupman RW Pickens 《Canadian Metallurgical Quarterly》1998,22(7):1421-1429
Mild, severe, and dyssocial subtypes of alcohol dependence, previously identified among Caucasian men from the Epidemiologic Catchment Area study, were also identified among Caucasian men and women with DSM-IV alcohol dependence from the National Longitudinal Alcohol Epidemiologic Survey (n = 2,703; 1,746 respectively). These subtypes were not identified among African American and Hispanic American men or women with DSM-IV alcohol dependence. Among Caucasians with alcohol dependence, the subtypes were characterized by differential loading on three dimensions: genetic, general environmental, and dyssocial environmental symptom scales developed in a prior twin study. The mild subtype (60% of men and 66% of women) was distinguished by low mean scores on all three scales; the dyssocial subtype (24% of men and 20% of women) by low mean genetic and general environmental scores but high mean dyssocial environmental scores; and the severe subtype (16% of men and 14% of women) by high scores on the genetic and general environmental scales. These subtypes also showed the expected distinctions in clinical characteristics. The severe subtype showed greater comorbid drug dependence and major depression, more treatment seeking, and a higher prevalence of parental alcoholism. The severe subtype also showed significantly greater genetic influence adjusted for overall severity of alcohol dependence (genetic ratio). Only the severe subtype showed a pattern of scale scores and clinical characteristics suggestive of substantial genetic influence. The present study indicates a robustness of the typology originally developed among DSM-III alcohol-dependent Caucasian men by empirical extension of the subtypes to a different sample of Caucasian men and, separately, Caucasian women. The use of this typology may aid in distinguishing between Caucasian alcohol-dependent individuals on the basis of relative genetic influence, enabling genetic, behavioral, and epidemiological investigations to reduce genetic or environmental "noise" and better focus on specific aspects of alcohol dependence. 相似文献
159.
160.