全文获取类型
收费全文 | 55755篇 |
免费 | 6955篇 |
国内免费 | 4072篇 |
专业分类
电工技术 | 4925篇 |
技术理论 | 10篇 |
综合类 | 6221篇 |
化学工业 | 2425篇 |
金属工艺 | 1312篇 |
机械仪表 | 3977篇 |
建筑科学 | 4511篇 |
矿业工程 | 2619篇 |
能源动力 | 902篇 |
轻工业 | 1420篇 |
水利工程 | 2274篇 |
石油天然气 | 2322篇 |
武器工业 | 641篇 |
无线电 | 9809篇 |
一般工业技术 | 3097篇 |
冶金工业 | 1848篇 |
原子能技术 | 185篇 |
自动化技术 | 18284篇 |
出版年
2024年 | 211篇 |
2023年 | 933篇 |
2022年 | 1565篇 |
2021年 | 1962篇 |
2020年 | 2113篇 |
2019年 | 1510篇 |
2018年 | 1603篇 |
2017年 | 1936篇 |
2016年 | 2167篇 |
2015年 | 2591篇 |
2014年 | 4537篇 |
2013年 | 3724篇 |
2012年 | 5077篇 |
2011年 | 5008篇 |
2010年 | 3558篇 |
2009年 | 3487篇 |
2008年 | 3453篇 |
2007年 | 3896篇 |
2006年 | 3516篇 |
2005年 | 2976篇 |
2004年 | 2430篇 |
2003年 | 2043篇 |
2002年 | 1422篇 |
2001年 | 1111篇 |
2000年 | 1009篇 |
1999年 | 682篇 |
1998年 | 460篇 |
1997年 | 379篇 |
1996年 | 326篇 |
1995年 | 248篇 |
1994年 | 220篇 |
1993年 | 137篇 |
1992年 | 108篇 |
1991年 | 64篇 |
1990年 | 57篇 |
1989年 | 43篇 |
1988年 | 38篇 |
1987年 | 16篇 |
1986年 | 61篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1973年 | 4篇 |
1959年 | 4篇 |
1958年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
21.
Using a comprehensive set of drop weight impact test data (h50) newly compiled from literature for 308 materials, a recent approach to predict impact sensitivities of nitro compounds is generalized to most explosive substances of interest. Compared to previous ones, this procedure is more thoroughly validated and exhibits a good predictive value. Furthermore, it yields new insight into the physical mechanisms involved, explaining for instance the unexpected desensitization of some oxygen-deficient triazoles upon nitration. 相似文献
22.
为解决依赖装维上门鉴别光网络单元故障带来的不便,可以从机器视觉入手实现自动化故障识别。近年,ImageNet挑战赛的成功推动了物体识别技术的跨越式发展,特别是基于卷积的深度学习技术在视觉识别方面已经达到人类水平,为光网络单元故障的自动识别提供了技术基础。文章对识别光网络单元的工作状态进行了研究,将设备工作状态分为7个场景,提出了利用手机APP采集图片识别故障的解决方案并投入了实际生产;重点阐述了深度学习模块的设计与实现,提出一种通过算法整合的方式综合运用物体检测和图像分类算法,分3阶段逐步求精,解决了图片过滤,光网络单元型号和状态识别等问题,实现了基于计算机视觉自动识别光网络单元故障。从数据上看产品的端到端准确率超过84%,识别速度达到10 FPS,月均提供服务超过1万人次,在减少用户等待的同时节约了人力资源。 相似文献
23.
Simulating the psychological experience of human vision,a road extraction model based on the format tower is proposed to extract the road in the high resolution remote sensing image from the perspective of morphology.Firstly,based on the spectral and texture information,the suspected road targets are extracted by using segmentation technology.Then these targets are classified according to their reliability and extract the road targets for each category.Finally,three types of identified road information are verified and merged,and the continuous smooth road extraction results are obtained.Experiments on real high resolution images show that the results are consistent with the visual perception of the human eye,and the overall classification accuracy is higher,indicating that the algorithm is effective and feasible and has good use value. 相似文献
24.
摘 要:针对城市地理信息平台构建过程中存在的数据获取困难、研发成本较高等问题,
引入开源技术,对基于开源数据、开源开发平台与开源工具的城市地理信息平台构建技术进行
研究。所提出的城市地理信息平台由数据模块与可视化模块 2 部分组成。为构建数据模块,由
开源地理信息项目(OSM)获取了建筑与区划数据,并设计了建筑合并算法以提升数据质量。建
筑数据随之基于行政区划分级存储,通过由 ASP. NET 构建的数据接口提供给具体应用。可视
化模块则基于开源地理信息系统(GIS)项目 Cesium 实现,并设计了完善的用户界面。以北京市
为例,完成了原型系统的开发与测试,证实了该技术体系的可行性,通过开源技术降低平台研
发成本,推进城市地理信息平台的研究与应用。 相似文献
25.
Considering autonomous mobile robots with a variety of specific functions as a kind of service, when there are many types and quantities of services and the density of regional services is large, proposing an algorithm of Circular Area Search (CAS) because of the problem of multi-robot service scheduling in various areas. Firstly, Django is used as the web framework to build the Service-Oriented Architecture (SOA) multi-robot service cloud platform, which is the basic platform for multi-service combination. Then, the service type, the latitude and longitude and the scoring parameters of the service are selected as the service search metrics to design the CAS algorithm that based on the existing service information registered in MySQL and the Gaode Map for screening optimal service, and then providing the service applicant with the best service. Finally, the service applicant applies for the self-driving tour service as an example to perform performance simulation test on the proposed CAS algorithm. The results show that the CAS algorithm of the multi-robot service cloud platform proposed in this paper is practical compared to the global search. And compared with the Greedy Algorithm experiment, the service search time is reduced about 58% compared with the Greedy Algorithm, which verifies the efficiency of CAS algorithm. 相似文献
26.
《Food Control》2015
A telephone survey was carried out on 13,486 randomly selected households located in the Abruzzo region (central Italy). Three questionnaires were specifically designed in relation to three different groups of foods (Meat and meat products, Fishery products, Fruit and vegetables). Questions were mainly focused on the amount and number of purchases, type of retailer, and home food handling practices with respect to the week prior to the interview. Data were classified according to a multilingual thesaurus system (LanguaL). Results allowed to estimate domestic purchases (in kg) per capita for different food categories. The category “Red meat/Cattle” accounted for a large part of purchases in the “meat and meat products” group (10.9 kg per capita/year; 32.2% of purchases in the group) while the category “Fish or related organism/Fish” was the most purchased in the “fishery products” group (6.9 kg per capita/year; 63.3%). The aggregation of more detailed characteristics enabled the identification of popular categories of foods, such as “Red meat/Cattle/Divided into pieces” (25% of the “meat and meat products” group). Significant differences (p < 0.05) were found between the four different provinces (L'Aquila, Chieti, Pescara and Teramo) with respect to “Poultry/Chicken” and “Red meat/Cattle” categories. Householders were also asked about post-purchase food handling practices that might be hazardous to food safety. More than 20% of those surveyed stated that they thawed frozen meat at room temperature. The degree of doneness after cooking of different food categories was generally high: over 90% of products purchased in the majority of meat and fish categories were properly cooked. However a noticeable proportion of householders (about 15%) reported medium or rare cooking of “Red meat/Cattle” and “Red meat/Swine”. Differences (p < 0.05) were also found between consumers of different ages, with people over 65 years old being more prone to freeze meat and cook it thoroughly.The survey was carried out in a specific geographic area and on a statistically significant sample of households, thus allowing a collection of data on domestic habits relating to food purchases and home food handling practices. This information should be included in the framework of quantitative microbial risk assessment (QMRA) models as a measure of the actual exposure of consumers to pathogenic microorganism. The LanguaL system also proved to be a practical language-independent method useful not only to identify and describe food items but also to classify them according to specific food safety characteristics. 相似文献
27.
范文跃 《信息安全与通信保密》2006,(8):66-68
在分析移动智能平台安全需求基础上,从逻辑原理、硬件组成、软件系统三个层面提出了移动智能平台的可信计算体系结构,之后提出了包含十种可信计算应用功能的全景图。 相似文献
28.
Service composition for generic service graphs 总被引:1,自引:0,他引:1
Service composition is a promising approach to multimedia service provisioning, due to its ability to dynamically produce new multimedia content, and to customize the content for individual client devices. Previous research work has addressed various aspects of service composition such as composibility, QoS-awareness, and load balancing. However, most of the work has focused on applications where data flow from a single source is processed by intermediate services and then delivered to a single destination. In this paper, we address the service composition problem for multimedia services that can be modeled as directed acyclic graphs (DAGs). We formally define the problem and prove its NP hardness. We also design a heuristic algorithm to solve the problem. Our simulation results show that the algorithm is effective at finding low-cost composition solutions, and can trade off computation overhead for better results. When compared with a hop-by-hop approach for service composition, our algorithm can find composition solutions that aress 10% smaller in cost, even when the hop-by-hop approach uses exhaustive searches. 相似文献
29.
30.
塔北地区储层敏感性综合预测 总被引:4,自引:4,他引:0
综合分析地质、地震及测井资料,可以准确地预测储层的敏感性。以地质分析及敏感性实验资料为基础,以测井资料为标定手段,以地震信息为横向预测导向,综合处理各种信息,从而实现对区域储层的敏感性预测。其中,利用测井资料预测储层敏感性是关键,须采用多参数相关系数法进行单井储层敏感性分析。以塔北地区侏罗系为例,综合各类信息进行了储层敏感性处理,分析结果表明,该区储层速敏弱,水敏、盐敏、碱敏和酸敏程度中等,与其储层敏感性实验结果基本吻合。 相似文献