全文获取类型
收费全文 | 288093篇 |
免费 | 23383篇 |
国内免费 | 12047篇 |
专业分类
电工技术 | 17697篇 |
技术理论 | 53篇 |
综合类 | 27737篇 |
化学工业 | 35695篇 |
金属工艺 | 12789篇 |
机械仪表 | 15703篇 |
建筑科学 | 39244篇 |
矿业工程 | 16687篇 |
能源动力 | 9853篇 |
轻工业 | 22714篇 |
水利工程 | 12172篇 |
石油天然气 | 14905篇 |
武器工业 | 4166篇 |
无线电 | 21653篇 |
一般工业技术 | 20007篇 |
冶金工业 | 14761篇 |
原子能技术 | 1943篇 |
自动化技术 | 35744篇 |
出版年
2024年 | 797篇 |
2023年 | 3334篇 |
2022年 | 6517篇 |
2021年 | 9023篇 |
2020年 | 8639篇 |
2019年 | 6214篇 |
2018年 | 5803篇 |
2017年 | 7397篇 |
2016年 | 9173篇 |
2015年 | 10102篇 |
2014年 | 20342篇 |
2013年 | 16926篇 |
2012年 | 21090篇 |
2011年 | 23234篇 |
2010年 | 17159篇 |
2009年 | 17640篇 |
2008年 | 16045篇 |
2007年 | 19559篇 |
2006年 | 17851篇 |
2005年 | 15536篇 |
2004年 | 13067篇 |
2003年 | 11489篇 |
2002年 | 9341篇 |
2001年 | 7745篇 |
2000年 | 6383篇 |
1999年 | 4997篇 |
1998年 | 3461篇 |
1997年 | 2943篇 |
1996年 | 2421篇 |
1995年 | 1988篇 |
1994年 | 1659篇 |
1993年 | 1162篇 |
1992年 | 947篇 |
1991年 | 662篇 |
1990年 | 572篇 |
1989年 | 505篇 |
1988年 | 291篇 |
1987年 | 221篇 |
1986年 | 202篇 |
1985年 | 210篇 |
1984年 | 156篇 |
1983年 | 125篇 |
1982年 | 72篇 |
1981年 | 83篇 |
1980年 | 92篇 |
1979年 | 43篇 |
1978年 | 23篇 |
1977年 | 22篇 |
1964年 | 25篇 |
1959年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
为了提升高校实验数据处理水平,高校实验室的相关建设工作已经步入正轨,但层出不穷的信息安全问题也向高校实验室计算机网络维护工作提出了新的挑战。文章从现阶段高校实验室计算机网络的相关建设工作出发,简要论述引发网络故障的具体原因,并对其诊断技术进行探讨。 相似文献
82.
本文结合HTH电路的复杂性等特征分析与实际应用现状,研究了HTH电路的具体检测技术方法并对当前热点技术进行对比分析,探讨了HTH电路检测方法的技术发展趋势。 相似文献
83.
为测试倾斜摄影测量技术路线,并通过实际项目的应用,解决传统古建筑建模过程中存在的时间成本高、难以还原复杂场景等问题。按照倾斜摄影技术的技术路线,进行朱氏宗祠建筑测绘试验,并通过基于altizure软件建立三维模型来展现倾斜摄影测量技术流程。验证无人机倾斜摄影应用于古建筑三维建模的可行性和可操作性。 相似文献
84.
本文对国内外的电视技术发展现状进行了充分的研究和分析,并对超高清电视系统的相关图像技术参数进行了分析和介绍。 相似文献
85.
The Vehicle Routing Problem with Simultaneous Pickup and Delivery (VRPSPD) is an extension to the classical Vehicle Routing Problem (VRP), where customers may both receive and send goods simultaneously. The Vehicle Routing Problem with Mixed Pickup and Delivery (VRPMPD) differs from the VRPSPD in that the customers may have either pickup or delivery demand. However, the solution approaches proposed for the VRPSPD can be directly applied to the VRPMPD. In this study, an adaptive local search solution approach is developed for both the VRPSPD and the VRPMPD, which hybridizes a Simulated Annealing inspired algorithm with Variable Neighborhood Descent. The algorithm uses an adaptive threshold function that makes the algorithm self-tuning. The proposed approach is tested on well-known VRPSPD and VRPMPD benchmark instances derived from the literature. The computational results indicate that the proposed algorithm is effective in solving the problems in reasonable computation time. 相似文献
86.
Baofeng Hou Hong He Ruixiu Jia Meilong Fu Yanbin Cao Shaoqun He Liwen Luo Youqing Huang 《应用聚合物科学杂志》2019,136(10):47161
The synthesis and performance of a novel temperature-tolerant foamed resin for enhanced oil recovery were investigated using various methods, including infrared, NMR, scanning electron microscopy (SEM), and displacement experiments. Polycondensation of furfuryl alcohol prepolymers was confirmed by the infrared and NMR results. The poor temperature tolerance of furfuryl alcohol prepolymers after gelation at high temperatures is mainly due to the fracture of furan rings. The addition of ester additives is an effective method of increasing the temperature tolerance of the prepared foamed resins and can effectively reduce the weight-loss rate of the polycondensation products. The SEM results show that the skeleton structure of the foamed resin remains intact after high-temperature treatment. Thus, the novel plugging agent system has excellent thermal stability and still has a high strength (>0.8 MPa) after high-temperature aging treatment for 40 days, giving the prepared foamed resin a good plugging performance (plugging rate > 91%) at 250 °C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47161. 相似文献
87.
An antibacterial peptide (AMP), i.e., nisin, was covalently bound to gelatin through a protein–protein coupling. Various reaction conditions were tested to study and optimize parameters of grafting e.g., orientation and density of AMP, which could impact the final antibacterial activity of the modified biopolymer. Modification was investigated by Fourier transform infrared (FT‐IR) spectroscopy and zeta potential. The antibacterial activity of the nisin‐enriched gelatin was evaluated against two staphylococci bacterial strains, i.e., Staphylococus epidermidis and Staphylococcus aureus. A higher activity was found for gelatin modified at pH = 7.4 revealing an influence of the nisin orientation on the protein antibacterial property. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41825. 相似文献
88.
Health information technology (IT) is a promising way to achieve safer medication management in the delivery of healthcare. However, human factors/ergonomics dictates that in order to make the complex, cognitive work of healthcare delivery safer, health IT must properly support human cognition. This means, for example, that new health IT must reduce, not increase, workload during safety-critical tasks. The present study was the first to quantitatively assess the short- and long-term impact of bar coded medication administration (BCMA) IT on nurses' mental workload as well as on perceived medication safety. One-hundred seventy registered nurses across 3 dissimilar clinical units at an academic, freestanding pediatric hospital in the Midwest US participated in surveys administered before, 3 months after, and 12 months after the hospital implemented BCMA. Nurses rated their external mental workload (interruptions, divided attention, being rushed) and internal mental workload (concentration, mental effort) during medication administration tasks as well as the likelihood of each of three medication safety events: medication administration errors, medication errors on the clinical unit, and clinical unit-level adverse drug events. Clinical unit differences were assessed. Findings generally confirmed the hypothesis that external but not internal mental workload was associated with the perceived likelihood of a medication safety event. Comparisons of mental workload from pre- to post-BCMA revealed statistically significant changes in the critical care unit only. Medication safety appeared to improve over the long term in the hematology/oncology unit only. In the critical care and medical/surgical units, medication safety exhibited short-term improvements that were eliminated over time. Changes in mental workload and medication safety, two classically microergonomic constructs, were deeply embedded in macroergonomic phenomena. These included the fit between the BCMA system and the nature of nursing work, the process of BCMA implementation, and BCMA interactions with concurrent changes occurring in the hospital. Findings raise questions about achieving sustainable performance improvement with health IT as well as the balance between micro- and macroergonomic approaches to studying technology change.Relevance to industryDesigners must consider how technology changes cognitive work, including mental workload. Hospitals and other implementers of technology must ensure that new technology fits its users, their tasks, and the context of use, which may entail tailoring implementation, for example, to specific clinical units. Evaluators must look over time to assess both changes in cognitive work and implementation issues. Healthcare practitioners must also recognize that new technology means a complex transformation to an already complex sociotechnical system, which calls for a macroergonomic approach to design and analysis. 相似文献
89.
《Intermetallics》2015
An equiatomic CoCrFeNiMn high-entropy alloy was synthesized by mechanical alloying (MA) and spark plasma sintering (SPS). During MA, a solid solution with refined microstructure of 10 nm which consists of a FCC phase and a BCC phase was formed. After SPS consolidation, only one FCC phase can be detected in the HEA bulks. The as-sintered bulks exhibit high compressive strength of 1987 MPa. An interesting magnetic transition associated with the structure coarsening and phase transformation was observed during SPS process. 相似文献
90.
Commercialization of technologies has attracted increasing attention over the past years due to its role in improving national competitiveness. Iran has not been an exception as the country's policy-makers have been actively engaged in crafting national policies to facilitate and promote commercialization of technologies. The popularity of the existing policies in this field, however, has not been properly researched. Our research, by following a survey study methodology, aims for the first time to address this gap. The study looks at popularity of governmental policies aimed at supporting commercialization of patented technologies in Iran, based on the careful study of 10 cases of successfully commercialized patented technologies in Iran. Our results indicate that the commercialization process of the studied patented technologies was very much affected by some company/technology-specific characteristics. The study shows that the two policy measures with the highest perceived popularity were the financial supports and the services offered by incubation centers. Our results also show that some of the existing supportive policy measures did not serve the intended purposes and some other measures need to be fine-tuned, as far as the studied cases are concerned, such as frequently held invention and innovation exhibitions and the government-supported media coverage. 相似文献