全文获取类型
收费全文 | 1737篇 |
免费 | 26篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 106篇 |
化学工业 | 471篇 |
金属工艺 | 32篇 |
机械仪表 | 35篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 65篇 |
轻工业 | 135篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 125篇 |
一般工业技术 | 340篇 |
冶金工业 | 231篇 |
原子能技术 | 37篇 |
自动化技术 | 157篇 |
出版年
2023年 | 5篇 |
2022年 | 28篇 |
2021年 | 28篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 15篇 |
2016年 | 30篇 |
2015年 | 18篇 |
2014年 | 37篇 |
2013年 | 74篇 |
2012年 | 54篇 |
2011年 | 90篇 |
2010年 | 51篇 |
2009年 | 58篇 |
2008年 | 80篇 |
2007年 | 80篇 |
2006年 | 63篇 |
2005年 | 55篇 |
2004年 | 59篇 |
2003年 | 61篇 |
2002年 | 50篇 |
2001年 | 38篇 |
2000年 | 35篇 |
1999年 | 44篇 |
1998年 | 117篇 |
1997年 | 67篇 |
1996年 | 49篇 |
1995年 | 44篇 |
1994年 | 30篇 |
1993年 | 44篇 |
1992年 | 27篇 |
1991年 | 25篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 27篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 20篇 |
1984年 | 23篇 |
1983年 | 10篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 15篇 |
1977年 | 5篇 |
1976年 | 16篇 |
1974年 | 5篇 |
1967年 | 4篇 |
排序方式: 共有1769条查询结果,搜索用时 15 毫秒
1.
A. Nakano T. Shimazaki M. Sekiya H. Shiozawa K. Ohtsuka A. Aoyagi T. Iwakiri Z. Mikami M. Sato Y. Sugino K. Kinoshita T. Matsuoka T. Imamura Y. Takayama K. Yamamoto 《International Journal of Hydrogen Energy》2021,46(29):15649-15659
Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa. 相似文献
2.
In a plant consisting of parallelized microreactors (MRs), the product quality is lowered because of a lack of flow uniformity among them when blockage occurs. It is not practical to install sensors in every MR from the viewpoint of cost when detecting the blocked MRs. In the previous study, the multiple blockage detection (MBD) method using a small number of sensors was proposed, but its performance became low when the number of sensors decreased. Here, the conventional algorithm for MBD is improved by considering the process behavior on blockage occurrence, and the effectiveness of the improved algorithm is demonstrated through a numerical case study. The effects of flow distributor types and sensor types on the MBD performance are numerically investigated. 相似文献
3.
4.
On an earthspace propagation path with the low elevation angle of 10 deg, the phase between co- and crosspolar signals occasionally showed rapid and irregular fluctuations during fine weather. These fluctuations were generally significant during the daytime, and were strongly in phase with the occurrence of the copolar amplitude scintillations. This could be attributed to the combined effects of the crosspolar phase pattern of the receiving antenna and small fluctuations of the angle of arrival of the radiowaves. 相似文献
5.
A method was developed for administering intrathecal pharmacotherapy in a rat model of spinal cord injury. The effects of intrathecal administration of nimodipine on spinal cord blood flow (SCBF) and evoked potentials (EPs) were measured in the normal and injured spinal cord. It had previously been shown that systemic nimodipine caused severe hypotension after spinal cord injury. After baseline SCBF and EPs, 15 uninjured rats were blindly allocated to one of three groups: one placebo group (n = 5); and two groups with intrathecal nimodipine, 0.05 mg/kg (n = 5), or 0.2 mg/kg (n = 5). Ten other rats received a 35 g acute clip compression injury of the spinal cord for 1 minute and, were allocated to one of two groups: placebo (n = 5); and intrathecal nimodipine 0.05 mg/kg (n = 5) given 60 min after injury. In the uninjured groups, neither 0.05 nor 0.2 mg/kg of nimodipine increased SCBF during, or 30 min after, intrathecal infusion. However, the mean arterial blood pressure (MABP) decreased significantly to 69.73.1% after the infusion of 0.2 mg/kg nimodipine and did not recover by 98 min. In all three groups of uninjured rats, the amplitude of the cerebellar EP was decreased 30 min after infusion. After spinal cord injury, there were significant decreases in MABP, SCBF and EP amplitude in both placebo and treatment groups, but there was no therapeutic benefit from nimodipine. Thus, intrathecal infusion of nimodipine did not prevent the hypotension encountered with systemic administration and exerted no beneficial effect on SCBF or EPs after acute spinal cord injury. 相似文献
6.
Shingo Hirano Akio Kawabata Masaru Yoshinaka Ken Hirota Osamu Yamaguchi 《Journal of the American Ceramic Society》1995,78(5):1414-1416
A compound denoted as (Ce0.75 Zr0.25 )O2 (Ce, ZrO8 ) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C. 相似文献
7.
Cold-rolling texture and partially recrystallized texture of polycrystalline 3 pct Si-Fe were investigated using high-resolution
electron backscattered diffraction (EBSD) method. From the measurement on a deformed grain with {211}〈011〉∼{111}〈011〉 orientations,
deformation bands with {12 4 1}〈014〉 orientation were found. It turned out that the orientation rotation relationship between
deformation bands and surrounding deformed grain can be explained by the activation of the slip system, which has a common
slip plane with an adjacent grain. Oriented nucleation of recrystallized grains with {12 4 1}〈014〉 orientation was observed
in a deformed grain with {211}〈011〉∼{111}〈011〉 orientation. Exactly the same orientation relationship that was observed between
deformed grain and the deformation bands was also observed between the deformed grain and the recrystallized grain. A hypothesis
that recrystallization nuclei are generated directly from the deformation bands formed by an activation of the slip system
that has a common slip plane of neighboring deformed grains was proposed from the present experimental results. 相似文献
8.
Directional couplers are successfully fabricated on acrylic substrates using polymers synthesised from deuterated methacrylate and deuterated fluoromethacrylate monomers. The excess loss of a 50 mm long coupler is about 0.7 dB including waveguide and fibre coupling losses. A novel method is proposed for tuning the coupling ratio. By bending the coupler, high precision control of within 1% is attained without optical polarisation dependence.<> 相似文献
9.
S Yamaji K Ishii M Sasaki T Imamura H Kitagaki S Sakamoto E Mori 《Canadian Metallurgical Quarterly》1997,38(9):1471-1474
We studied changes in cerebral perfusion and oxygen metabolism to elucidate the pathophysiological nature and clinical significance of white matter hyperintensities in Alzheimer's disease (AD). METHODS: Sixteen AD patients (age 71.6 +/- 3.1 yr) whose T2-weighted MR images showed white matter hyperintensities, and 16 age-matched AD patients (age 71.0 +/- 4.3 yr) without white matter hyperintensities were compared. Regional cerebral blood flow (CBF), oxygen metabolism (CMRO2) and oxygen extraction fraction (OEF) were measured by using (15)O steady-state method and PET. RESULTS: There was no significant difference in cognitive impairment between the two groups. Compared to the patients without white matter hyperintensities, those with them had significantly low CBF values and significantly high OEF values in all cortical and white matter regions. However, there were no significant differences in CMRO2 values between the two groups. Severity of white matter hyperintensities correlated with the mean cortical and mean white matter OEF. CONCLUSION: In AD patients, white matter hyperintensities on T2-weighted MR images represent ischemic changes in which oxygen metabolism and function are fairly compensated. These changes are not disease-specific but are age-associated coincidences, as in normal aging with or without vascular risk factors. 相似文献
10.
Masafumi Itoh Osamu Sakurada Minoru Hashiba Kouichi Hiramatsu Yukio Nurishi 《Journal of Materials Science》1996,31(12):3321-3324
An average shell volume occupied in the adsorption layer on alumina by a polyacrylic acid ammonium salts molecule (PAA) defined as the average area occupied by an adsorbed PAA on alumina multiplied by the average thickness of the water layer at the limit of thickening, has been calculated from the adsorbed amount of PAA and from the flow points of alumina in the presence of PAA of different molecular weights. A steric effect of the PAA dispersant on the dispersion of alumina resulted in a flow with no yield stress. This was due to the change of the extension of PAA in the adsorption shell from a sphere to an ellipsoid with a long axis which exceeded the effective distance that the van der Waals attraction force reaches at a molecular weight for the PAA of between 10 000–20 000. 相似文献