全文获取类型
收费全文 | 4350篇 |
免费 | 219篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 81篇 |
综合类 | 2篇 |
化学工业 | 683篇 |
金属工艺 | 87篇 |
机械仪表 | 54篇 |
建筑科学 | 249篇 |
矿业工程 | 33篇 |
能源动力 | 104篇 |
轻工业 | 503篇 |
水利工程 | 35篇 |
石油天然气 | 23篇 |
无线电 | 397篇 |
一般工业技术 | 668篇 |
冶金工业 | 711篇 |
原子能技术 | 31篇 |
自动化技术 | 911篇 |
出版年
2023年 | 35篇 |
2022年 | 34篇 |
2021年 | 108篇 |
2020年 | 74篇 |
2019年 | 114篇 |
2018年 | 146篇 |
2017年 | 122篇 |
2016年 | 158篇 |
2015年 | 115篇 |
2014年 | 159篇 |
2013年 | 278篇 |
2012年 | 221篇 |
2011年 | 255篇 |
2010年 | 192篇 |
2009年 | 188篇 |
2008年 | 217篇 |
2007年 | 209篇 |
2006年 | 181篇 |
2005年 | 144篇 |
2004年 | 146篇 |
2003年 | 102篇 |
2002年 | 131篇 |
2001年 | 55篇 |
2000年 | 60篇 |
1999年 | 58篇 |
1998年 | 163篇 |
1997年 | 114篇 |
1996年 | 77篇 |
1995年 | 51篇 |
1994年 | 62篇 |
1993年 | 51篇 |
1992年 | 44篇 |
1991年 | 31篇 |
1990年 | 39篇 |
1989年 | 39篇 |
1988年 | 16篇 |
1987年 | 23篇 |
1986年 | 26篇 |
1985年 | 30篇 |
1984年 | 35篇 |
1983年 | 20篇 |
1982年 | 22篇 |
1981年 | 20篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 15篇 |
1977年 | 22篇 |
1976年 | 35篇 |
1974年 | 16篇 |
1973年 | 15篇 |
排序方式: 共有4572条查询结果,搜索用时 15 毫秒
41.
Tom Fitzpatrick 《电子测试》2005,(11):34-42
虽然目前的IC设计持续以惊人的速度复杂化,但设计者仍然希望可以通过先进的验证工作提高工作效率.所谓的先进验证工作便是将测试平台自动化(Test-Bench Automation)和正式属性检测(Formal Property Checking)两功能添加到功能验证(Functional Verification)的流程之中.本文将主要探讨其中的基本概念、价值以及使用方法,进而帮助读者了解. 相似文献
42.
43.
SL Barker MJ McNicholas D Kader P Abdon T Adalberth D McGurty DI Rowley CM Walker 《Canadian Metallurgical Quarterly》1998,43(6):400-403
A cohort of 39 patients (28 male, 11 female) that had undergone total meniscectomy as adolescents (mean age 16 years) underwent FISP 3D Magnetic Resonance Imaging at a mean follow up of 30 years. The presence of meniscal tissue was assessed by two independent observers blinded to the operation details. The volume of any meniscal tissue present was calculated. A posterior horn remnant was seen in 57% of medial and 45% of lateral meniscectomy cases. The mean volume of an operated medial meniscal remnant was 0.29 mL compared with a mean volume of 1.15 mL for an intact medial meniscus. The mean volume of an operated lateral meniscal remnant was 0.30 mL compared with 1.07 mL for an intact lateral meniscus. We have shown that the incidence of incomplete excision of the posterior horn is more common after total medial meniscectomy, and that at a mean follow up of 30 years there is no convincing in vivo MRI evidence of long-term meniscal regeneration. 相似文献
44.
The IRDA IrLAP protocol is analytically modelled. Throughput performance is examined with bit error rate, window size, and turnaround times. It is shown that for the proposed 16 Mbit/s and 127 frame maximum window size extension the link BER quality becomes critical if maximum throughput is to be achieved. A window size of 60 is less sensitive to bit error rate variations. Reducing the minimum turnaround time is always beneficial 相似文献
45.
46.
In the last decade there was growing interest in strategic management literature about factors that influence a company's ability to use IT. There is general consensus that knowledge and competency are necessary in developing an IT capability, but there is very little understanding of what the necessary competencies are, and how they influence IS usage in different contexts. The small and medium-sized enterprise context is particularly interesting for two reasons: it constitutes a major part of the economy and it has been relatively unsuccessful in exploiting e-business. 相似文献
47.
MH Edwards S Pierangeli X Liu JH Barker G Anderson EN Harris 《Canadian Metallurgical Quarterly》1997,96(12):4380-4384
BACKGROUND: Previous studies have demonstrated that human monoclonal and polyclonal anticardiolipin antibodies have thrombogenic properties in vivo. Using such a model in which these antibodies have been shown to increase both the size of an induced thrombus and the duration of time in which such a clot lasts, we investigated whether hydroxychloroquine alters the dynamics of such thrombus formation. METHODS AND RESULTS: Three groups of nine mice were injected with purified immunoglobulin G (IgG) from a patient with the antiphospholipid syndrome (IgG-APS) and then fed with hydroxychloroquine at various doses (100, 6, and 3 mg/kg body wt). Three control groups of mice were also studied, including mice injected with IgG-APS and then fed with placebo, as well as two other groups injected with IgG from normal human serum and fed either hydroxychloroquine or placebo. A standardized thrombogenic injury was subsequently induced in the femoral vein of each mouse and the area (size) of thrombus measured as well as the total period of time that thrombus was present. Mice treated with hydroxychloroquine and IgG-APS showed significantly smaller thrombi that persisted for a shorter period of time compared with animals treated with IgG-APS and placebo. CONCLUSIONS: Hydroxychloroquine significantly diminished both thrombus size and total time of thrombus formation in mice previously injected with IgG-APS. 相似文献
48.
This study examined people's willingness to restrain themselves during a naturally occurring social dilemma situation—the 1991 California water shortage. The findings suggest that people are more willing to support authorities who make water conservation decisions when these authorities use fair decision-making procedures. Procedural justice effects were not found to be influenced by the perceived severity of the resource scarcity or the favorability of the authorities' decisions. Rather, they were primarily based on concerns for having positive, relational bonds to the authorities. These relational effects were found to be stronger for those respondents who identify more with their community. The study suggests that the effectiveness of authorities is primarily linked to the nature of their social bonds with community members. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
49.
S.A. Brindhaban P.H. Barker M.J. Keeling W.B. Wood 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1994,340(3):436-441
The energies of resonances in the 27Al(p, γ) reaction at 992 and 1317 keV and of the threshold of the 27Al(p, n) reaction at 5804 keV have been measured accurately with respect to a 1 V standard. Both calibration energies and energies suitable for Q-value calculations are given. Corrections are made for the effects of the energy distribution of the proton beam, of nonuniform energy loss of the protons in the target and of ionisation of the target atoms. 相似文献
50.
A multiparameter wearable physiologic monitoring system for space and terrestrial applications. 总被引:4,自引:0,他引:4
Carsten W Mundt Kevin N Montgomery Usen E Udoh Valerie N Barker Guillaume C Thonier Arnaud M Tellier Robert D Ricks Robert B Darling Yvonne D Cagle Nathalie A Cabrol Stephen J Ruoss Judith L Swain John W Hines Gregory T A Kovacs 《IEEE transactions on information technology in biomedicine》2005,9(3):382-391
A novel, unobtrusive and wearable, multiparameter ambulatory physiologic monitoring system for space and terrestrial applications, termed LifeGuard, is presented. The core element is a wearable monitor, the crew physiologic observation device (CPOD), that provides the capability to continuously record two standard electrocardiogram leads, respiration rate via impedance plethysmography, heart rate, hemoglobin oxygen saturation, ambient or body temperature, three axes of acceleration, and blood pressure. These parameters can be digitally recorded with high fidelity over a 9-h period with precise time stamps and user-defined event markers. Data can be continuously streamed to a base station using a built-in Bluetooth RF link or stored in 32 MB of on-board flash memory and downloaded to a personal computer using a serial port. The device is powered by two AAA batteries. The design, laboratory, and field testing of the wearable monitors are described. 相似文献