全文获取类型
收费全文 | 119368篇 |
免费 | 13807篇 |
国内免费 | 8101篇 |
专业分类
电工技术 | 8737篇 |
技术理论 | 23篇 |
综合类 | 17491篇 |
化学工业 | 6952篇 |
金属工艺 | 3173篇 |
机械仪表 | 7496篇 |
建筑科学 | 13904篇 |
矿业工程 | 4425篇 |
能源动力 | 1987篇 |
轻工业 | 7684篇 |
水利工程 | 4738篇 |
石油天然气 | 3668篇 |
武器工业 | 1345篇 |
无线电 | 17481篇 |
一般工业技术 | 7122篇 |
冶金工业 | 3635篇 |
原子能技术 | 860篇 |
自动化技术 | 30555篇 |
出版年
2024年 | 739篇 |
2023年 | 1973篇 |
2022年 | 3455篇 |
2021年 | 3747篇 |
2020年 | 3740篇 |
2019年 | 2947篇 |
2018年 | 2665篇 |
2017年 | 3614篇 |
2016年 | 4019篇 |
2015年 | 4839篇 |
2014年 | 9193篇 |
2013年 | 7052篇 |
2012年 | 9075篇 |
2011年 | 9705篇 |
2010年 | 7614篇 |
2009年 | 8046篇 |
2008年 | 7617篇 |
2007年 | 9213篇 |
2006年 | 8083篇 |
2005年 | 6848篇 |
2004年 | 5380篇 |
2003年 | 4453篇 |
2002年 | 3483篇 |
2001年 | 2786篇 |
2000年 | 2349篇 |
1999年 | 1753篇 |
1998年 | 1203篇 |
1997年 | 960篇 |
1996年 | 899篇 |
1995年 | 704篇 |
1994年 | 580篇 |
1993年 | 462篇 |
1992年 | 424篇 |
1991年 | 281篇 |
1990年 | 264篇 |
1989年 | 224篇 |
1988年 | 181篇 |
1987年 | 110篇 |
1986年 | 106篇 |
1985年 | 67篇 |
1984年 | 75篇 |
1983年 | 54篇 |
1982年 | 36篇 |
1981年 | 63篇 |
1980年 | 43篇 |
1979年 | 32篇 |
1978年 | 17篇 |
1977年 | 12篇 |
1975年 | 18篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Jean-Claude Malela-Majika Sandile Charles Shongwe Olatunde Adebayo Adeoti 《Quality and Reliability Engineering International》2021,37(8):3314-3322
The sensitivity of a monitoring scheme depends on many factors including the variance of the charting statistic which is very important in the computation of the control limits. This paper discusses the computation of the variance of the recently proposed hybrid homogeneously weighted moving average (HHWMA) scheme which was based on an incorrect assumption. The correct variance is used to evaluate the run-length characteristics of the HHWMA scheme. It is observed that the incorrect variance has a significant impact on the sensitivity (or performance) of the HHWMA scheme. 相似文献
2.
3.
The supervision of a hybrid power plant, including solar panels, a gas microturbine and a storage unit operating under varying solar power profiles is considered. The Economic Supervisory Predictive controller assigns the power references to the controlled subsystems of the hybrid cell using a financial criterion. A prediction of the renewable sources power is embedded into the supervisor. Results deteriorate when the solar power is unsteady, owing to the inaccuracy of the predictions for a long-range horizon of 10 s. The receding horizon is switched between an upper and a lower value according to the amplitude of the solar power trend. Theoretical results show the relevance of horizon switching, according to a tradeoff between performance and prediction accuracy. Experimental results, obtained in a Hardware In the Loop (HIL) framework, show the relevance of the variable horizon approach. Power amplifiers allow us to simulate virtual components, such as a gas microturbine, and to blend their powers with that of real devices (storage unit, real solar panels). In this case, fuel savings, reaching 15%, obtained under unsteady operating conditions lead to a better overall performance of the hybrid cell. The overall savings obtained in the experiments amount to 12%. 相似文献
5.
电网的安全水平主要取决于其使用产品的质量是否过关。如果产品的质量较好,则能建造出优质的电网,电网的安全水平便会随之提高。因此,应加强对产品质量的监督管理,从而提高电网的安全水平。我们可建立质量监督管理系统,及时抽检出质量不过关的产品,从而消除电网运行过程中潜在的安全隐患。 相似文献
6.
《Planning》2015,(1)
目的 探讨气管上段腺样囊性癌的临床病理特征及诊断和鉴别诊断要点。方法 收集2000年1月至2014年2月在北京协和医院确诊的4例气管上段腺样囊性癌病例,通过光镜、免疫组织化学及组织化学染色分析其临床病理特征、免疫组织化学特点、诊断及鉴别诊断要点。结果 4例气管上段腺样囊性癌患者中,男1例,女3例,平均年龄47岁(38~57岁);既往均无腺样囊性癌病史,1例患者既往有结节性甲状腺肿手术史。镜下检查4例均为筛状/管状型腺样囊性癌,3例累及甲状腺组织,3例累及神经组织,未见淋巴结受累。免疫组织化学染色示4例P16、CD117、BCL2、P63、SMA均阳性,Ki67指数平均8%,TTF1和P53均阴性;4例中基底膜样物胶原Ⅳ阳性;组织化学染色示AB/PAS阳性。术后均接受总剂量为48~56 Gy的放疗,随访6~120个月,平均72.5个月,1例术后96个月复发,3例随访期间无复发及转移。结论 气管上段腺样囊性癌是罕见的原发于气管的低度恶性肿瘤,肿瘤生长缓慢,就诊时多数已侵及甲状腺组织,需要与原发于甲状腺的恶性肿瘤相鉴别,特别是在甲状腺穿刺及术中冰冻检查时。结合电子喉气管镜下表现、典型的形态学及免疫组织化学和组织化学染色有助于准确诊断。手术难以切除干净,术后放疗对延缓疾病复发有一定帮助。 相似文献
7.
8.
针对现有混合入侵检测模型仅定性选取特征而导致检测精度较低的问题,同时为了充分结合误用检测模型和异常检测模型的优势,提出一种采用信息增益率的混合入侵检测模型.首先,利用信息增益率定量地选择特征子集,最大程度地保留样本信息;其次,采用余弦时变粒子群算法确定支持向量机参数构建误用检测模型,使其更好地平衡粒子在全局和局部的搜索能力,然后,选取灰狼算法确定单类支持向量机参数构建异常检测模型,以此来提高对最优参数的搜索效率和精细程度,综合提高混合入侵检测模型对攻击的检测效果;最后,通过两种数据集进行仿真实验,验证了所提混合入侵检测模型具有较好的检测性能. 相似文献
9.
In this paper, we propose a novel change detection method for synthetic aperture radar images based on unsupervised artificial immune systems. After generating the difference image from the multitemporal images, we take each pixel as an antigen and build an immune model to deal with the antigens. By continuously stimulating the immune model, the antigens are classified into two groups, changed and unchanged. Firstly, the proposed method incorporates the local information in order to restrain the impact of speckle noise. Secondly, the proposed method simulates the immune response process in a fuzzy way to get an accurate result by retaining more image details. We introduce a fuzzy membership of the antigen and then update the antibodies and memory cells according to the membership. Compared with the clustering algorithms we have proposed in our previous works, the new method inherits immunological properties from immune systems and is robust to speckle noise due to the use of local information as well as fuzzy strategy. Experiments on real synthetic aperture radar images show that the proposed method performs well on several kinds of difference images and engenders more robust result than the other compared methods. 相似文献
10.
Electrocardiogram is the most commonly used tool for the diagnosis of cardiologic diseases. In order to help cardiologists to diagnose the arrhythmias automatically, new methods for automated, computer aided ECG analysis are being developed. In this paper, a Modified Artificial Bee Colony (MABC) algorithm for ECG heart beat classification is introduced. It is applied to ECG data set which is obtained from MITBIH database and the result of MABC is compared with seventeen other classifier's accuracy.In classification problem, some features have higher distinctiveness than others. In this study, in order to find higher distinctive features, a detailed analysis has been done on time domain features. By using the right features in MABC algorithm, high classification success rate (99.30%) is obtained. Other methods generally have high classification accuracy on examined data set, but they have relatively low or even poor sensitivities for some beat types. Different data sets, unbalanced sample numbers in different classes have effect on classification result. When a balanced data set is used, MABC provided the best result as 97.96% among all classifiers.Not only part of the records from examined MITBIH database, but also all data from selected records are used to be able to use developed algorithm on a real time system in the future by using additional software modules and making adaptation on a specific hardware. 相似文献