全文获取类型
收费全文 | 734篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 5篇 |
综合类 | 5篇 |
化学工业 | 52篇 |
金属工艺 | 12篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 15篇 |
轻工业 | 17篇 |
石油天然气 | 1篇 |
无线电 | 12篇 |
一般工业技术 | 62篇 |
冶金工业 | 544篇 |
原子能技术 | 1篇 |
自动化技术 | 22篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 2篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 22篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 4篇 |
2006年 | 9篇 |
2005年 | 1篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 20篇 |
1998年 | 159篇 |
1997年 | 85篇 |
1996年 | 70篇 |
1995年 | 46篇 |
1994年 | 20篇 |
1993年 | 24篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 28篇 |
1976年 | 46篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有751条查询结果,搜索用时 140 毫秒
741.
742.
A food recording electronic device to simplify the collection of dietary data is described. The need for a subject to maintain a quantitative account of food intake, and for a dietitian to subsequently code this record prior to computer analysis, are both eliminated using this approach. In combination with an electronic kitchen balance, the recorder, which is based upon a single-board computer (SBC) and special keyboard, enables the weight, food type and time of consumption of each food to be recorded automatically in response to simple key entry. The resident program, transparent to the user, allows data from surveys lasting up to three weeks to be stored for subsequent serial downloading to a host computer. 相似文献
743.
RI Damper 《Canadian Metallurgical Quarterly》1976,15(6):488-500
Subjects were presented with an initially stationary binaural image formed by the fusion of two identical pulses, without interaural time difference (ITD), at the two ears. The image was then made to traverse the subject's auditory perceptual space by introducing ITD, varying linearly with time, under computer control. The direction of movement, i.e. towards the right or left ear, could be reversed by the listener, by pressing a button. Subjects were requested to keep the image central, by pressing the button when they judged that deviation from subjective centre had occurred. Experiments of this type can be considered as analogous to Békésy audiometry, where the subject automatically traces his threshold of hearing, in that here the listener traces out his auditory perceptual centre as it varies with time. Hence, equivalent analyses to those employed for Békésy audiometry are possible. Subsequent to the initial part of the experiment, an additional pulse was added to one channel, preceding the original pulse, to form a pulse pair. The monaural masking of the original pulse by this additional pulse thus acts to shift the pre-existing binaural image. The effect of varying the amplitude and onset time of the masking pulse, relative to the original pulse, on the Békésy-type trace was examined. 相似文献
744.
Mahdieh Shahmardani Ruslan Logvinov Tomáš Babinský Stefan Guth Shubhadip Paul Abhishek Biswas Napat Vajragupta Alexander Hartmaier 《Advanced Engineering Materials》2023,25(15):2300103
The present work deals with the cyclic deformation behavior of additively manufactured austenitic stainless steel 316L. Since fatigue experiments are complex and time-consuming, it is important to develop accurate numerical models to predict cyclic plastic deformation and extrapolate the limited experimental results into a wider range of conditions, considering also the microstructures obtained by additive manufacturing. Herein, specimens of 316L steel are produced by powder bed fusion of metals with laser beams (PBF-LB/M) with different parameters, and cyclic strain tests are performed to assess their deformation behavior under cyclic loads at room temperature. Additionally, a micromechanical model is set up, based on representative volume elements (RVE) mimicking the microstructure of the experimentally tested material that is characterized by electron backscatter diffraction (EBSD) analysis. With the help of these RVEs, the deformation-dependent internal stresses within the microstructure can be simulated in a realistic manner. The additively manufactured specimens are produced with their loading axis either parallel or perpendicular to the building direction, and the resulting anisotropic behavior under cyclic straining is investigated. Results highlight significant effects of specimen orientation and crystallographic texture and only a minor influence of grain shape on cyclic behavior. 相似文献
745.
Satoh T Ruslan RI Gotoh S Akitsu T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(4):788-797
In this work we propose a novel circuit design: a double-resonance oscillator. Its oscillation shows two oscillation modes: frequency locking to the quartz crystal resonance and LC resonance oscillation. Transition of the oscillation mode and the strength of oscillation are analyzed and reviewed for the fundamental mode in comparison with a Colpitts oscillator. The experimental results support the estimates of negative resistance for the double-resonance oscillator compared with the LC oscillator. 相似文献
746.
747.
Zhiming Li Baolong Zheng Yitian Wang Troy Topping Yizhang Zhou Ruslan Z. Valiev Aidang Shan Enrique J. Lavernia 《Journal of Materials Science》2014,49(19):6656-6666
To ascertain the influence of severe plastic deformation (SPD) on a Ti–Nb–Ta–Zr (TNTZ) alloy, we studied the room temperature mechanical behavior and microstructural evolution of an ultrafine-grained (UFG) Ti–36Nb–2Ta–3Zr (wt%) alloy prepared via equal-channel angular pressing (ECAP) of the as-hot-extruded alloy. The tensile behavior, phase composition, grain size, preferred orientation, and dislocation density of the UFG alloy, processed under different conditions, were analyzed and discussed. Compared to the as-hot-extruded alloy, the ECAP-processed TNTZ alloy (3 passes) exhibited approximately 40 and 88 % increase in average ultimate strength and yield strength, respectively. Moreover, as the number of ECAP passes increased from 3 to 6, the TNTZ alloy exhibited not only the expected increase in ultimate and yield strength values, but also a slight increase in elongation. Our results suggest that the deformation mechanisms that govern the behavior of the as-hot-extruded coarse grained (CG) TNTZ alloy during ECAP involve a combination of stress-induced martensitic transformation and dislocation activity. In the case of the ECAP-processed UFG TNTZ alloy, the deformation mechanism is proposed to involve two components: first, dislocation activity induced by the strain field imposed during ECAP; and second, the formation of α″ martensite phase during the early stages of ECAP which eventually transforms into β phase during continued deformation. We propose that the deformation mechanism governing the room temperature behavior of the TNTZ alloy strongly depends on the grain size of the β phase. 相似文献
748.
Clinical psychiatry and neurology requires a creation of new means with difficult many component range of psychotropic action, so psychoemotional disturbances "boundary type" and difficult mental disorders have high level of heterogeneity, various clinical manifestations, which are caused by different pathogenetic factors. One of the most often used preparation for the treatment of these diseases is anxiolytic medications. It is known that anxiolytic action combines with anticonvulsive. Perspective medications are simple amides and ethers of 2-oksoindolin-3-glyoxylic acid, which have not recognized and practically observed. The aim of this research is to determine anticonvulsant action in 2-oksoindolin-3-glyoxylic acid derivatives on the model of acute myoclonic pentylentetrazol, piktrotoxic, and bikukullin convulsions. In experiments on mature mice of both sex Wistar line were studied an influence of ethyl ester 4-[2-hydroxy-2-(2-oxo-1,2-dihydro-indol-3-ylidene)-acetylamino]-butyric acid and 2-hydroxy-N-naphthalen-l-yl-2-(2-oxo-l,2-dihydro-indol-3-ylidene)-acetamide on chemoinduced epileptogenesis. An intake of proconvulsants is accompanied by a development of syndrome convulsion, which was estimated by convulsion's intensity (grades), latent period of convulsions (sec.), number of convulsions acts, and duration of convulsions (sec.) and number of survived animals in a group. It was showed that a combination of 2-hydroxy-N-naphthalen-1-yl-2-(2-oxo-1,2-dihydro-indol-3-ylidene)-acetamide (12 acetamide mg/kg) is similar to reference preparation diazepam in (2 mg/kg) which decreased a manifestation of syndrome convulsion. It demonstrated an increase of intensity of convulsions, decrease of latent period of the convulsion's start which is caused by all blockers GAMKA-receptors, decrease of number convulsive acts on the background of korazol and pikrotoxin, a decrease of convulsive syndrome duration during an intake ofkorazol and bikukullin, and a decrease of animal's mortalit 相似文献
749.
Grain Boundary Phenomena in an Ultrafine‐Grained Al–Zn Alloy with Improved Mechanical Behavior for Micro‐Devices
下载免费PDF全文
![点击此处可从《Advanced Engineering Materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
750.
WJ Chu HP Hetherington RI Kuzniecky T Simor GF Mason GA Elgavish 《Canadian Metallurgical Quarterly》1998,51(2):472-479
OBJECTIVE: To compare the phosphorous metabolite ratios in the mesial temporal lobe of healthy volunteers (n = 20) with the corresponding ratios in patients with temporal lobe epilepsy (n = 30) using 31P NMR spectroscopic imaging and to lateralize the seizure focus in temporal lobe epilepsy patients using various phosphorous metabolite ratios-phosphocreatine to inorganic phosphate (PCr/Pi), PCr to adenosine triphosphate (PCr/gamma-ATP), and (gamma-ATP/Pi)--and to compare with clinical lateralization results. METHODS: All 31P NMR spectroscopic imaging studies were performed on a high-field, 4.1 T, whole-body NMR spectroscopic imaging system using a 31P/1H double-tuned volume coil. RESULTS: We found an average reduction of 15% in the PCr/Pi and gamma-ATP/Pi ratios compared with the corresponding ratios in healthy volunteers in the entire mesial temporal lobe, and more than a 30% reduction in these two ratios in the anterior region of the epileptogenic mesial temporal lobe. These ratios were also reduced significantly in the ipsilateral lobe when compared with their corresponding values in the contralateral lobe. In patients we lateralized the seizure focus, based on these 31P NMR data, and compared the results with the clinical lateralization. The lateralization based on either the PCr/Pi or the gamma-ATP/Pi ratio yielded a correspondence of 70 to 73% with the final clinical lateralization. In the subgroup of patients (n = 9) that needed intracranial EEG for the presurgical lateralization because of inconclusive results from the noninvasive methods, a 78% correspondence was found with the 31P NMR-based lateralization, whereas MRI provided a correspondence of only 33%, and scalp EEG provided a correspondence of only 56%. CONCLUSIONS: These results suggest the utility of adding the 31P NMR method to the group of noninvasive modalities used for presurgical decision making in temporal lobe epilepsy patients. 相似文献