全文获取类型
收费全文 | 24613篇 |
免费 | 2932篇 |
国内免费 | 1718篇 |
专业分类
电工技术 | 2694篇 |
技术理论 | 2篇 |
综合类 | 2710篇 |
化学工业 | 1974篇 |
金属工艺 | 542篇 |
机械仪表 | 1833篇 |
建筑科学 | 1585篇 |
矿业工程 | 777篇 |
能源动力 | 480篇 |
轻工业 | 3381篇 |
水利工程 | 588篇 |
石油天然气 | 1373篇 |
武器工业 | 296篇 |
无线电 | 2089篇 |
一般工业技术 | 1799篇 |
冶金工业 | 846篇 |
原子能技术 | 149篇 |
自动化技术 | 6145篇 |
出版年
2024年 | 81篇 |
2023年 | 412篇 |
2022年 | 800篇 |
2021年 | 922篇 |
2020年 | 976篇 |
2019年 | 806篇 |
2018年 | 719篇 |
2017年 | 897篇 |
2016年 | 917篇 |
2015年 | 1007篇 |
2014年 | 1690篇 |
2013年 | 1488篇 |
2012年 | 1889篇 |
2011年 | 2028篇 |
2010年 | 1515篇 |
2009年 | 1547篇 |
2008年 | 1343篇 |
2007年 | 1647篇 |
2006年 | 1417篇 |
2005年 | 1140篇 |
2004年 | 1000篇 |
2003年 | 878篇 |
2002年 | 757篇 |
2001年 | 573篇 |
2000年 | 512篇 |
1999年 | 383篇 |
1998年 | 332篇 |
1997年 | 281篇 |
1996年 | 208篇 |
1995年 | 195篇 |
1994年 | 147篇 |
1993年 | 114篇 |
1992年 | 94篇 |
1991年 | 74篇 |
1990年 | 60篇 |
1989年 | 59篇 |
1988年 | 35篇 |
1987年 | 28篇 |
1986年 | 29篇 |
1985年 | 16篇 |
1984年 | 27篇 |
1983年 | 14篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 27篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1961年 | 11篇 |
1959年 | 12篇 |
1957年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
情景意识(SA)问题在数字化核电厂中更为突出。为识别班组共享情景意识(SSA)水平及行为形成因子(PSF)对班组SSA的影响,基于情景意识全面评估技术(SAGAT)建立一种班组SSA测量和计算方法并进行模拟机实验。结果表明,个体SA(ISA)水平与SSA水平有关,ISA级别越高,SSA级别越高;ISA和班组SSA都受到PSF的影响,PSF的状态水平越高,ISA和SSA的水平越高;对于不同的实验场景,操纵员的ISA水平和班组SSA水平不同,这表明风险场景的症状越明显及知识经验水平越好,ISA和SSA水平就越高。最后,通过被试的自评价识别当前PSF的状态水平,主要不良的PSF是班组沟通和合作水平、压力水平、人-机界面等。这些评估结果为提高数字化核电厂人因可靠性和安全水平提供了理论支持。 相似文献
42.
阐述了液压活塞式惯容器的基本结构、工作原理与承载力大的特点,建立了考虑摩擦力、寄生阻尼力和油液弹性效应的惯容器非线性力学模型。在数控液压伺服激振台上对液压活塞式惯容器进行了力学性能试验,基于试验结果,利用Matlab参数辨识工具箱对非线性力学模型中的参数进行辨识。在此基础上建立了包含液压活塞式惯容器非线性因素的车辆惯容器 弹簧 阻尼器(inerter-spring-damper,简称ISD)悬架动力学模型并进行了仿真分析。结果表明,当考虑液压活塞式惯容器非线性因素时,车辆ISD悬架系统的车身加速度均方根值增加5%,而轮胎动载荷与悬架动行程均方根值均有所减小,降低了车辆的行驶平顺性。 相似文献
43.
Mri Miczi Mria Golda Balzs Kunkli Tibor Nagy Jzsef Tzsr Jnos Andrs Mtyn 《International journal of molecular sciences》2020,21(24)
The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease-19 (COVID-19) being associated with severe pneumonia. Like with other viruses, the interaction of SARS-CoV-2 with host cell proteins is necessary for successful replication, and cleavage of cellular targets by the viral protease also may contribute to the pathogenesis, but knowledge about the human proteins that are processed by the main protease (3CLpro) of SARS-CoV-2 is still limited. We tested the prediction potentials of two different in silico methods for the identification of SARS-CoV-2 3CLpro cleavage sites in human proteins. Short stretches of homologous host-pathogen protein sequences (SSHHPS) that are present in SARS-CoV-2 polyprotein and human proteins were identified using BLAST analysis, and the NetCorona 1.0 webserver was used to successfully predict cleavage sites, although this method was primarily developed for SARS-CoV. Human C-terminal-binding protein 1 (CTBP1) was found to be cleaved in vitro by SARS-CoV-2 3CLpro, the existence of the cleavage site was proved experimentally by using a His6-MBP-mEYFP recombinant substrate containing the predicted target sequence. Our results highlight both potentials and limitations of the tested algorithms. The identification of candidate host substrates of 3CLpro may help better develop an understanding of the molecular mechanisms behind the replication and pathogenesis of SARS-CoV-2. 相似文献
44.
冰载荷是影响船舶冰区航行期间结构安全的重要环境载荷。船舶的冰压监测通常采用应变传感器,合理地布放传感器是识别冰载荷的基础。通过对比船体外板结构试验中的冲击载荷和不同测试方案下的应变信号,确定了最佳应变传感器布放方案;采用Green核函数方法建立了船体外板结构应变冲击载荷间的响应关系,并对采集信号在噪声影响下反演的不适定性进行了分析;采用Tikhonov正则化方法克服了载荷反演过程中出现的数值不稳定问题;最后将试验中的响应用到载荷识别分析中,反演的载荷可以较为准确地反映冲击载荷的时域特征并且载荷识别精度良好。 相似文献
45.
电子背散射衍射(Electron Backscatter Diffraction, EBSD)是研究材料显微结构的重要手段之一, 通过EBSD获取的菊池衍射花样是材料内部微观晶体结构的直观反映。本研究通过识别菊池花样中的对称轴, 结合晶体对称定律, 提出了一种利用菊池花样进行晶体对称性分析和晶体结构鉴定的方法。通过该方法成功对三个未知样品的对称性和晶体结构进行了判断。其中一个样品确定到所属晶系, 另两个样品锁定到部分点群, 通过确定晶系和点群排除了部分不符合对称性的相鉴定结果。研究结果表明, 利用菊池花样进行对称性分析是判断晶体结构的有效方法。同现有方法相比, 菊池衍射花样法大大缩小了相鉴定的检索范围, 显著提高了相鉴定的准确性和可靠性, 是一种有望用于新一代EBSD设备的标定技术。 相似文献
46.
目的 对2019年9月4日发生在云南省楚雄彝族自治州的一起误食光硬皮马勃中毒事件进行调查分析,明确中毒原因,总结中毒特点及救治方法,为该蘑菇中毒事件的处置提供借鉴。方法 收集中毒病例资料、进行流行病学调查、对蘑菇样品进行形态学和分子生物学鉴定。结果 2例患者各进食了约50 g购买于市场的马勃后,出现了腹痛、恶心、呕吐、腹泻及低血压的症状,潜伏期0.5~1 h,经过对症治疗后好转出院。蘑菇标本经形态学和分子生物学鉴定为光硬皮马勃。结论 此次事件是因误食光硬皮马勃引起的急性中毒事件。光硬皮马勃与可食用的云南硬皮马勃外形相似,常因误食而中毒。鉴于很多毒蘑菇与一些食用菌形态上极为相似而导致误采误食,建议不要随意采食野生蘑菇。 相似文献
47.
《全球能源互联网(英文)》2021,4(6):619-630
The technology deployed for lithium-ion battery state of charge (SOC) estimation is an important part of the design of electric vehicle battery management systems. Accurate SOC estimation can forestall excessive charging and discharging of lithium-ion batteries, thereby improving discharge efficiency and extending cycle life. In this study, the key lithium-ion battery SOC estimation technologies are summarized. First, the research status of lithium-ion battery modeling is introduced. Second, the main technologies and difficulties in model parameter identification for lithium-ion batteries are discussed. Third, the development status and advantages and disadvantages of SOC estimation methods are summarized. Finally, the current research problems and prospects for development trends are summarized. 相似文献
48.
The distribution of Trogoderma granarium Everts has expanded steadily in recent years. This is a very destructive coleopteran species with many economic implications for the trade of grains in countries where it is present. Therefore, it is important to gather data that can confirm or reject the pest’s establishment in a particular country. Spain has been cited as a location where the species is established; however, the present study demonstrates that no actual data support its stablishment in Spain. We surveyed fifteen storage premises (mills and warehouses for animal feed, wheat, and rice) distributed along the Iberian Peninsula over two years. We used traps baited with Trogoderma spp. sex pheromone to conduct the survey. Collected samples were morphologically and molecularly identified, since the morphological identification of this species is difficult. Although we found populations of T. inclusum in most of the sampled premises, and even T. variabile in one of them, no T. granarium was found in any of them. Abundant samples of other coleopterans were captured in the traps, including Oryzaephilus surinamensis, Tribolium spp., Sitophilus spp., Cryptolestes ferrugineus, Lasioderma serricorne and Rhyzopertha dominica. In conclusion, no T. granarium was found in our samplings in Spain. 相似文献
49.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen. 相似文献
50.
Maria Grazia Basanisi Gianfranco La Bella Gaia Nobili Rosa Coppola Annita Maria Damato Maria Assunta Cafiero Giovanna La Salandra 《International Journal of Food Science & Technology》2020,55(3):1145-1150
The authenticity and traceability of meat products are issues of primary importance to ensure food safety. Unfortunately, food adulteration (e.g. the addition of inexpensive cuts to minced meat products) and mislabelling (e.g. the inclusion of meat from species other than those declared) happens frequently worldwide. The aim of this study was to apply a droplet digital PCR assay for the detection and quantification (copies μL−1) of the beef, pork, horse, sheep, chicken and turkey in meat products. The analysis conducted on commercial meat showed the presence of traces of DNA from other animal species than those declared. We show that the method is highly sensitive, specific and accurate (accuracy = 100%). This method could be adopted by competent food safety authorities to verify compliance with the labelling of meat products and to ensure quality and safety throughout the meat supply chain, from primary production to consumption. 相似文献