全文获取类型
收费全文 | 43001篇 |
免费 | 3463篇 |
国内免费 | 2967篇 |
专业分类
电工技术 | 2720篇 |
技术理论 | 2篇 |
综合类 | 5578篇 |
化学工业 | 3134篇 |
金属工艺 | 2353篇 |
机械仪表 | 3163篇 |
建筑科学 | 1678篇 |
矿业工程 | 938篇 |
能源动力 | 467篇 |
轻工业 | 862篇 |
水利工程 | 687篇 |
石油天然气 | 1068篇 |
武器工业 | 522篇 |
无线电 | 5265篇 |
一般工业技术 | 4751篇 |
冶金工业 | 1821篇 |
原子能技术 | 490篇 |
自动化技术 | 13932篇 |
出版年
2024年 | 140篇 |
2023年 | 493篇 |
2022年 | 891篇 |
2021年 | 1050篇 |
2020年 | 896篇 |
2019年 | 706篇 |
2018年 | 636篇 |
2017年 | 840篇 |
2016年 | 928篇 |
2015年 | 1141篇 |
2014年 | 2004篇 |
2013年 | 2104篇 |
2012年 | 2395篇 |
2011年 | 2503篇 |
2010年 | 2380篇 |
2009年 | 2351篇 |
2008年 | 2385篇 |
2007年 | 2974篇 |
2006年 | 2753篇 |
2005年 | 2672篇 |
2004年 | 2250篇 |
2003年 | 2184篇 |
2002年 | 1826篇 |
2001年 | 1713篇 |
2000年 | 1530篇 |
1999年 | 1234篇 |
1998年 | 1069篇 |
1997年 | 935篇 |
1996年 | 800篇 |
1995年 | 727篇 |
1994年 | 613篇 |
1993年 | 454篇 |
1992年 | 346篇 |
1991年 | 264篇 |
1990年 | 205篇 |
1989年 | 187篇 |
1988年 | 142篇 |
1987年 | 98篇 |
1986年 | 84篇 |
1985年 | 91篇 |
1984年 | 89篇 |
1983年 | 70篇 |
1982年 | 72篇 |
1981年 | 30篇 |
1980年 | 24篇 |
1979年 | 32篇 |
1978年 | 12篇 |
1977年 | 18篇 |
1966年 | 7篇 |
1964年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The main cause of death and serious disability in bicycle accidents is traumatic brain injury (TBI). The aim of this population-based study was to assess the incidence and costs of bicycle-related TBI across various age groups, and in comparison to all bicycle-related injuries, to identify main risk groups for the development of preventive strategies.Data from the National Injury Surveillance System and National Medical Registration were used for all patients with bicycle-related injuries and TBI who visited a Dutch emergency department (ED) between 1998 and 2012. Demographics and national, weighted estimates of injury mechanism, injury severity and costs were analysed per age group. Direct healthcare costs and indirect costs were determined using the incidence-based Dutch Burden of Injury Model.Between 1998 and 2012, the incidence of ED treatments due to bicycle-related TBI strongly increased with 54%, to 43 per 100,000 persons in 2012. However, the incidence of all bicycle-related injuries remained stable, from 444 in 1998 to 456/100,000 in 2012. Incidence of hospital admission increased in both TBI (92%) and all injuries from cycling (71%). Highest increase in incidence of both ED treatments and hospital admissions was seen in adults aged 55+. The injury rate of TBI per kilometre travelled increased (44%) except in children, but decreased (−4%) for all injuries, showing a strong decrease in children (−36%) but an increase in men aged 25+, and women aged 15+. Total costs of bicycle-related TBI were €74.5 million annually. Although bicycle-related TBI accounted for 9% of the incidence of all ED treatments due to cycling, it accounted for 18% of the total costs due to all bicycle-related injuries (€410.7 million). Children and adolescents (aged 0–24) had highest incidence of ED treatments due to bicycle-related injuries. Men in the working population (aged 15–64) had highest indirect costs following injuries from cycling, including TBI. Older cyclists (aged 55+) were identified as main risk group for TBI, as they had highest ED attendance, injury rate, injury severity, admission to hospital or intensive care unit, and costs.Incidence of ED treatments due to cycling are high and often involve TBI, imposing a high burden on individuals and society. Older cyclists aged 55+ were identified as main risk group for TBI to be targeted in preventive strategies, due to their high risk for (serious) injuries and ever-increasing share of ED visits and hospital admissions. 相似文献
2.
Wenshu Chen Jiajun Gu Yongping Du Fang Song Fanxing Bu Jinghan Li Yang Yuan Ruichun Luo Qinglei Liu Di Zhang 《Advanced functional materials》2020,30(25)
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions. 相似文献
3.
Multifunctional 3D Patternable Drug‐Embedded Nanocarrier‐Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation 下载免费PDF全文
4.
5.
6.
Kruk Menno R.; Halász József; Meelis Wout; Haller József 《Canadian Metallurgical Quarterly》2004,118(5):1062
Aggressive behavior induces an adrenocortical stress response, and sudden stressors often precipitate violent behavior. Experiments in rats revealed a fast, mutual, positive feedback between the adrenocortical stress response and a brain mechanism controlling aggression. Stimulation of the aggressive area in the hypothalamus rapidly activated the adrenocortical response, even in the absence of an opponent and fighting. Hypothalamic aggression, in turn, was rapidly facilitated by a corticosterone injection in rats in which the natural adrenocortical stress response was prevented by adrenalectomy. The rapidity of both effects points to a fast, mutual, positive feedback of the controlling mechanisms within the time frame of a single conflict. Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
基于TS101的PCI接口高速数据采集系统的设计 总被引:1,自引:0,他引:1
给出了基于TS101和PCI的双通道数据采集处理系统的设计方案。首先介绍了ADI公司新型数字信号处理(DSP)微处理器TS101和FLYBY数据传输模式,阐述了系统结构和工作原理,最后对如何利用TS101的FLYBY接口提高数据采集、存取效率和数据系统的逻辑控制进行了详细的论述。 相似文献
8.
串行和并行接口模式是A/D转换器诸多分类中的一种,但却是应用中器件选择的一个重要指标.在同样的转换分辨率及转换速度的前提下,不同的接口方式不但影响了电路结构,更重要的是将在高速数据采集的过程中对采样周期产生较大影响.本文通过12位串行ADC ADS7822和并行ADC ADS774与AT89C51的接口电路,给出二者采样时间的差异性. 相似文献
10.
MAX3100在80C196串口扩展中的应用 总被引:1,自引:0,他引:1
介绍采用新型的UART器件MAX3100为Intel单片机80C196扩展串口,给出了硬件设计和软件编程,并对关键技术进行了说明。 相似文献