全文获取类型
收费全文 | 431篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 89篇 |
金属工艺 | 14篇 |
机械仪表 | 16篇 |
建筑科学 | 10篇 |
矿业工程 | 5篇 |
能源动力 | 10篇 |
轻工业 | 27篇 |
石油天然气 | 2篇 |
无线电 | 67篇 |
一般工业技术 | 102篇 |
冶金工业 | 46篇 |
原子能技术 | 6篇 |
自动化技术 | 45篇 |
出版年
2024年 | 4篇 |
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 21篇 |
2018年 | 27篇 |
2017年 | 20篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 32篇 |
2012年 | 23篇 |
2011年 | 13篇 |
2010年 | 14篇 |
2009年 | 21篇 |
2008年 | 13篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 12篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有443条查询结果,搜索用时 15 毫秒
21.
Molecular aspects of chemical and physical changes in adhesive joints caused by absorbed moisture were investigated. The focus was on the pre-damage stage that precedes the formation of voids and microcracks. A model and a commercial epoxy-amine formulation were studied. Local dynamics were monitored by broad-band dielectric relaxation spectroscopy (DRS). One portion of the absorbed water does not form hydrogen bonds with the network and gives rise to a fast relaxation process (termed γ) with activation energy of 28 kJ/mol. The local β dynamics are slowed down by the interactions between water and various sites on the network that include the ether oxygen, the hydroxyl group and the tertiary amine nitrogen. One particularly significant finding is that the average relaxation time for the β process above 20°C is of the order of nanoseconds or less and, hence, the detection and monitoring of this process hinges upon the ability to perform high-precision DRS at frequencies above 1 MHz. This is an important consideration in the ongoing efforts aimed at the implementation of DRS as nondestructive inspection (NDI) tool for adhesive joints. 相似文献
22.
23.
Kadiyan Neha Chatterjee R. S. Pranjal Pranshu Agrawal Pankaj Jain S. K. Angurala M. L. Biyani A. K. Sati M. S. Kumar Dheeraj Bhardwaj Ashutosh Champati Ray P. K. 《Bulletin of Engineering Geology and the Environment》2021,80(4):3217-3231
Bulletin of Engineering Geology and the Environment - The present study identified groundwater depletion–induced land subsidence by spaceborne differential interferometric SAR (DInSAR)... 相似文献
24.
Rakesh Kumar Soni Harjeet Singh Krishna Dutt Priyanka Arora 《Journal of Polymer Research》2010,17(3):411-427
The mixing torque behavior of ter blends of isotactic-polypropylene (iPP) with ethylene-propylene diene rubber (EPDM)/Nitrile
rubber (NBR) was studied with the help of Rheometer using resole type phenolic resin as a cross-linking agents. Systematic
changes with varying blend composition were observed in stress-strain behavior in the yield region viz., width of yield peak,
work of yield, yield stress and yield strain. Analysis of yield stress data was made on the basis of various mathematical
expressions of first power and two-thirds power laws of blend composition dependence and the porosity model. It led to consistent
result from the expressions about the variation of stress concentration effect in both uncross-linked and cross-linked blend
systems. With the aid of scanning electron microscopy (SEM) shapes and sizes of dispersed elastomer phase (EPDM / NBR) domains
at varying blend compositions were studied. 相似文献
25.
This paper presents a new contrast enhancement approach which is based on Cuckoo Search (CS) algorithm and DWT-SVD for quality improvement of the low contrast satellite images. The input image is decomposed into the four frequency subbands through Discrete Wavelet Transform (DWT), and CS algorithm used to optimize each subband of DWT and then obtains the singular value matrix of the low-low thresholded subband image and finally, it reconstructs the enhanced image by applying IDWT. The singular value matrix employed intensity information of the particular image, and any modification in the singular values changes the intensity of the given image. The experimental results show superiority of the proposed method performance in terms of PSNR, MSE, Mean and Standard Deviation over conventional and state-of-the-art techniques. 相似文献
26.
Dheeraj Gupta Apurbba Kumar Sharma 《Journal of Materials Engineering and Performance》2012,21(10):2165-2172
In the present work, cladding of hardfacing WC10Co2Ni powder on austenitic stainless steel has been developed through a novel processing technique. The clads were developed using microwave hybrid heating. The clad of average thickness ~2?mm has been developed through the exposure of microwave radiation at frequency 2.45?GHz and power 900?W for the duration of 360?s. The developed clads were characterized using field emission scanning electron microscope, X-ray elemental analysis, X-ray diffraction, and measurement of Vicker??s microhardness. The microstructure study of the clad showed good metallurgical bonding with substrate and revealed that clads are free from any visible interface cracking. Clads were formed with partial dilution of a thin layer of the substrate. The cermet microstructure mainly consists of relatively soft metallic matrix phase and uniformly distributed hard carbide phase with skeleton-like structure. The developed clads exhibit an average microhardness of 1064?±?99?Hv. The porosity of developed clad has been significantly less at approximately 0.89%. 相似文献
27.
Puspraj Singh Chauhan Sanjay Soni Yashu Shanker 《Wireless Personal Communications》2013,70(4):1683-1695
A novel approach to predict field strength in the shadow of a 3-D building scenario is presented. The field strength predicted by the proposed model is compared with available measurements and earlier predicted fields based on Fresnel-Kirchhoff theory. Two different scenarios have been considered to validate our model. The proposed model gives an improvement of 7.7 dB for Scenario 1; and 5.8 dB for Scenario 2. A good agreement between the prediction and the measurement is also observed. 相似文献
28.
C V Tomy R Nagarajan S K Malik Ram Prasad N C Soni Kalyan Adhikary 《Bulletin of Materials Science》1991,14(3):691-695
151Eu Mössbauer studies have been performed on the compounds EuBa2(Cu1?x Zn x )3O7?y withx=0·0, 0·025, 0·05, 0·075 and 0·1. The parent compound, EuBa2Cu3O7?y is superconducting with a transition temperature (T c ) of 88 K.T c is depressed as Zn is substituted for Cu in this system and the compounds withx>0·05 do not show superconductivity down to 12 K.151Eu Mössbauer studies at 295 K show a single Mössbauer line in all the compounds (whether superconducting or not) with isomer shift value typical of Eu3 + ion. Further, the isomer shift values are nearly independent ofx and the temperatures down to 10 K. These observations imply that the Cu-O network responsible for superconductivity is very weakly coupled to the Eu sublattice. 相似文献
29.
P K Mishra Shailendra Kumar G Ravikumar P Chaddah B A Dasannacharya Ram Prasad N C Soni 《Bulletin of Materials Science》1991,14(4):899-901
HighT
c
phase (T
c
∼ 110 K) has been obtained in Bi-Sr-Ca-Cu-O system by partially substituting Bi by Pb. Magnetic hysteresis has been measured
as a function of temperature. Critical current densities have been measured at 77 K both by transport and a.c. magnetization
method in bulk samples for various concentrations of Pb. The results show that substitution of 15 at % Pb for Bi is most preferable
for higher critical current density. 相似文献
30.
S Vaidyanathan BM Soni L Gopalan P Sett JW Watt G Singh J Bingley P Mansour KR Krishnan T Oo 《Canadian Metallurgical Quarterly》1998,36(12):838-846
Patients with chronic tetraplegia are prone to develop unique clinical problems which require readmission to specialised centres where the health professionals are trained specifically to diagnose, and treat the diseases afflicting this group of patients. An appraisal of the readmission pattern of tetraplegic patients will provide the necessary data for planning allocation of beds for treatment of chronic tetraplegic patients. Hospital records of patients with tetraplegia readmitted to the Regional Spinal Injuries Centre, Southport, UK between 1 January 1994 and 31 December 1995 were analyzed to find out the number of tetraplegic patients who required readmission, reasons for readmission, duration of hospital stay, and mortality among patients readmitted. During the 2-year period, 155 tetraplegic patients were readmitted and 44 of them (28.4%) required more than one readmission (total readmission episodes: 221); these patients occupied 4.5 beds which is equivalent to 11.5% of the total bed capacity of the spinal unit. Among the reasons for the readmissions, evaluation and care of urinary tract disorders topped the list with 96 readmission episodes (43.43%) involving 70 patients; the median hospital stay was 3 days, and 18 patients (26%) required more than one readmission during this period. One hospital bed was occupied by the tetraplegic patients requiring treatment/evaluation of urinary tract disorders. Assessment and treatment of cardio-respiratory diseases was the second most common reason for readmission with 51 readmission episodes pertaining to 27 patients having a median hospital stay of 6 days; 13 patients (48%) were readmitted more than once within this 2-year period. Treatment of cardio-respiratory diseases in chronic tetraplegic patients required 1.2 hospital beds yearly. Only five tetraplegic patients were readmitted for treatment of pressure sore(s); however they had a prolonged hospital stay (median duration: 101 days). Social reasons accounted for 13 readmission episodes concerning nine patients who stayed in the hospital for varying periods (median: 6.5 days; mean: 35 days). Four tetraplegic patients readmitted with acute chest infection expired. An 81 year-old tetraplegic died of myocardial infarction. Urinary sepsis, renal insufficiency, respiratory failure and intra-cerebral haemorrhage accounted for the demise of a 41 year-old tetraplegic patient following surgical removal of a large, impacted stone at the pelviureteric junction. A tetraplegic patient who was admitted with haematuria subsequently underwent cystectomy for squamous cell carcinoma of the urinary bladder; he developed secondaries and expired 5 months later. As more patients with high cervical spinal cord injury survive the initial period of trauma, and as the life expectancy of tetraplegic patients increases, it is likely that greater numbers of tetraplegic patients will be requiring readmission to spinal injuries centre. Although it may be possible to prevent some of the complications of spinal cord injury and hence the need for a readmission, progress in medicine and rehabilitation technology will create additional demands for readmissions of chronic tetraplegic patients in order to implement the newer therapeutic strategies. Thus a change in the pattern of readmission of chronic tetraplegic patients is likely to be the future trend and this should be taken into account while making plans for providing the optimum care to chronic tetraplegic patients. 相似文献