全文获取类型
收费全文 | 1368篇 |
免费 | 46篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 91篇 |
综合类 | 4篇 |
化学工业 | 387篇 |
金属工艺 | 43篇 |
机械仪表 | 31篇 |
建筑科学 | 23篇 |
矿业工程 | 1篇 |
能源动力 | 52篇 |
轻工业 | 95篇 |
水利工程 | 1篇 |
无线电 | 103篇 |
一般工业技术 | 229篇 |
冶金工业 | 195篇 |
原子能技术 | 45篇 |
自动化技术 | 116篇 |
出版年
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 38篇 |
2020年 | 28篇 |
2019年 | 20篇 |
2018年 | 30篇 |
2017年 | 29篇 |
2016年 | 40篇 |
2015年 | 35篇 |
2014年 | 54篇 |
2013年 | 70篇 |
2012年 | 61篇 |
2011年 | 85篇 |
2010年 | 49篇 |
2009年 | 65篇 |
2008年 | 49篇 |
2007年 | 41篇 |
2006年 | 50篇 |
2005年 | 48篇 |
2004年 | 31篇 |
2003年 | 35篇 |
2002年 | 34篇 |
2001年 | 30篇 |
2000年 | 20篇 |
1999年 | 18篇 |
1998年 | 61篇 |
1997年 | 38篇 |
1996年 | 29篇 |
1995年 | 27篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 19篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 14篇 |
1975年 | 5篇 |
1970年 | 4篇 |
排序方式: 共有1416条查询结果,搜索用时 0 毫秒
1.
2.
3.
It is necessary to determine the accurate reflectance of painted surfaces for the review of paint finishes by computer graphics (CG) before actual painting of the exterior color of automobiles, and for quality control during production and inspection processes. We have optimized a method for measuring reflectance by using a statistical technique. We have found that the reflectance of a painted surface is best measured at an incident angle of 60° and at five aspecular angles of 10°, 18°, 28°, 40°, and 90°. Our method makes it possible to accurately reproduce reflection characteristics of paint finishes containing special flake pigments, such as pearl mica. Also it was proved that our method can apply not only to solid and metallic coatings but to all painted surfaces. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 275–282, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20125 相似文献
4.
On the basis of new concept using a solid disperse phase we have developed an efficient catalytic solid-phase-system for epoxidations of alkenes using urea–hydrogen peroxide (urea–H2O2) complex and cetylpyridinium dodecatungstate ((CetylPy)10[H2W12O42]) catalyst on fluorapatite (FAp). The recovered solid catalyst phase was reused to keep the catalytic activity after several times. In the conceptual idea it is a key point that in situ solid-phase-activation of the catalyst with urea–H2O2 proceeds to form microcrystals of the active species dispersed on the solid phase. The dispersion of the catalyst on FAp in the case of tungstic acid (H2WO4) was suggested by EPMA analysis. We proposed the peroxo type of species keeping the parent polyoxometalate framework as novel active species from FT-IR spectroscopic studies. FAp phase plays important roles of dispersing the active species on its surface to have high catalytic activity and of stabilizing the active species to lead to high reusability. 相似文献
5.
Phenol novolac/poly (4-hydroxyphenylmaleimide) (PHPMI) blends were used as an epoxy resin hardener. The curing behavior of the above system and the thermal and mechanical properties of the cured epoxy resin were studied. It was not necessary to use a curing accelerator for this system, because PHPMI caused acceleration of the curing reaction. The curing mechanism of this system was investigated by using model compounds. Test pieces from the neat resins and the glass fiber reinforced resins were evaluated in terms of thermal and mechanical properties, respectively. It was found that heat resistance and mechanical properties were improved by increasing the amount of PHPMI in the hardener. 相似文献
6.
M Sato A Kondo S Otsuka H Tanabe N Matsuura K Hasegawa M Chin M Saiki 《Canadian Metallurgical Quarterly》1993,21(12):1143-1147
The authors report a rare case of a large cystic cervical neurinoma. A 45-year-old female was admitted to our clinic because of motor weakness of the right upper extremity, numbness of the right fingers and right posterior cervical pain. Metrizamide CT myelography demonstrated the outline of a low density mass. MRI showed a mass revealing low signal intensity on T1-weighted image, high signal intensity on T2-weighted image and marginal enhancement on contrast image with Gd-DTPA. The mass which was diagnosed as cystic tumor, was located in the intradural extramedullary space between C4 to C5 segments. After C4 through C5 laminectomy, the tumor was found to originate from the C5 anterior motor root. The tumor consisted mostly of a cystic part with a very thin solid compartment beneath the capsule. Postoperative course of the patient was uneventful. Although spinal neurinoma is one of the most common spinal tumors, an almost completely degenerated large cystic spinal neurinoma is extremely rare. MRI with Gd-DTPA was useful for the diagnosis of the cystic neurinoma by clearly enhancing the margin of the tumor. 相似文献
7.
8.
M Otsuka Y Ichiya Y Kuwabara M Sasaki T Yoshida T Fukumura K Masuda 《Canadian Metallurgical Quarterly》1995,16(12):1021-1025
The existence of the nigrofrontal dopaminergic pathway has been demonstrated in neuroanatomical studies. We evaluated the presynaptic nigrofrontal dopaminergic function using 18F-dopa (FD) positron emission tomography (PET). The multiple time PET data in the frontal cortex from 20 to 70 min post-injection for FD were evaluated by Patlak analysis using the cerebellar time-activity curve as an input function. The frontal FD uptake rate constants could not be determined in 5 of 12 normal volunteers because of large deviations in the plots. There were no significant differences between the subjects among whom the frontal FD uptake rate constants could or could not be determined regarding the amount of FD injected, the frontal 18F counts, or whether or not they were pretreated with carbidopa. The uptake constants were determined in 9 or 12 patients with parkinsonian syndrome. While the mean (+/- S.D.) uptake constants in patients with Parkinson's disease (2.89 +/- 0.06 x 10(-3), n = 4) and in patients with progressive supranuclear palsy (2.81 +/- 0.10 x 10(-3), n = 3) were not significantly different from those in the normal volunteers (2.93 +/- 0.14 x 10(-3)), those in two patients with corticobasal degeneration (2.42 and 2.46, respectively) decreased in comparison to the control values. Differences in the nigrofrontal presynaptic dopaminergic function as assessed by FD-PET may explain the different pathogenesis and also help to differentiate between corticobasal degeneration and other parkinsonian syndromes, such as Parkinson's disease and progressive supranuclear palsy. 相似文献
9.
10.
The Bi2O31bM2O5 films (M=V, Nb and Ta) were prepared by a rapid quenching technique using a twin-roller type equipment. Quenched film of pure Bi2O3 partially precipitated a tetragonal phase which differs from well-known β-Bi2O3 in structure. In every (Bi2O3)0.975 (M2O5)0.025 composition (2.5% M2O5), the tetragonal phase was obtained as single phase, and the tetragonality became greater than that of the pure Bi2O3. Beyond this composition, the tetragonality decreased to form δ-phase with a fcc structure with increasing the M2O5 content. The lowest V2O5 content forming a δ-phase was 5%, while a slight tetragonality still remained in the samples containing 10% Nb2O5 and 10% Ta2O5, respectively. From the measurement of the photoconductivities of the quenched films, it was proved that a photoconduction appeared in the tetragonal phase while no photoconductivity was observed in the cubic phase. The characteristic of the photoconduction was that a remarkable decrease in the resistivity was observed when a light of ca. 500 nm in wave length was irradiated on the films. 相似文献