全文获取类型
收费全文 | 1314篇 |
免费 | 42篇 |
专业分类
电工技术 | 160篇 |
综合类 | 2篇 |
化学工业 | 385篇 |
金属工艺 | 33篇 |
机械仪表 | 37篇 |
建筑科学 | 32篇 |
能源动力 | 80篇 |
轻工业 | 81篇 |
石油天然气 | 4篇 |
无线电 | 56篇 |
一般工业技术 | 257篇 |
冶金工业 | 93篇 |
原子能技术 | 48篇 |
自动化技术 | 88篇 |
出版年
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 26篇 |
2020年 | 12篇 |
2019年 | 21篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 31篇 |
2015年 | 17篇 |
2014年 | 46篇 |
2013年 | 75篇 |
2012年 | 51篇 |
2011年 | 98篇 |
2010年 | 56篇 |
2009年 | 75篇 |
2008年 | 78篇 |
2007年 | 57篇 |
2006年 | 52篇 |
2005年 | 43篇 |
2004年 | 36篇 |
2003年 | 46篇 |
2002年 | 45篇 |
2001年 | 26篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 49篇 |
1997年 | 22篇 |
1996年 | 31篇 |
1995年 | 32篇 |
1994年 | 14篇 |
1993年 | 23篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 5篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 24篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1972年 | 5篇 |
排序方式: 共有1356条查询结果,搜索用时 250 毫秒
1.
2.
A simple interface fracture test for ceramic environmental barrier coatings (EBCs) on ceramic matrix composites (CMCs) was developed. A variation on the asymmetric double cantilever beam (ADCB) test was proposed so that the interface toughness could be measured in a small specimen of simple shape without applying interlaminar loading to the CMC substrate. The proposed test was applied to an EBC consisting of a mullite layer and Si bond coat on a monolithic SiC substrate. A pre-crack was introduced by pop-in cracking, and then a notch overlapping the pre-crack was machined. The pre-crack was opened by inserting a wedge into the notch. From the critical notch opening displacement the crack starts to propagate, interface toughness is calculated. The measured interface toughness was 4.1?J/m2. Finally, the application range of the test was discussed and suggestions were made for introduction of the notch and pre-crack. 相似文献
3.
Shoji Nakamura Yuji Shibahara Atsushi Kimura Osamu Iwamoto Akihiro Uehara Toshiyuki Fujii 《Journal of Nuclear Science and Technology》2020,57(4):388-400
ABSTRACTThe thermal-neutron capture cross-section (σ0) and resonance integral (I0) were measured for the 135Cs(n,γ)136Cs reaction by an activation method and mass spectrometry. Because of difficulty in the preparation of pure 135Cs samples, we used 135Cs contained as an impurity in a normally available 137Cs standard solution. An isotope ratio of 135Cs and 137Cs in a standard 137Cs solution was measured by mass spectrometry to quantify 135Cs. Cesium-135 impurity along with the 137Cs standard solution was irradiated at the hydraulic conveyer of the research reactor in the Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott’s indices at an irradiation position. A gadolinium filter was used to measure the σ0, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of 137Cs, 136Cs and monitor wires. On the basis of Westcott’s convention, the σ0 and I0 values were derived as 8.57 ± 0.25 barn, and 45.3 ± 3.2 barn, respectively. The value of σ0 obtained in the present study agreed within the limits of uncertainties with the past-reported value of 8.3 ± 0.3 barn. 相似文献
4.
Shouko Nishida Masaya Shibano Hiroshi Kamitakahara Toshiyuki Takano 《International journal of molecular sciences》2015,16(12):29093-29102
We recently observed that the decanoylation of N-phenylthiocarbamoyl chitosan (2) with a mixture of decanoic anhydride and pyridine at 60 °C for 24 h afforded N,N-(decanoyl)phenythiocarbamoyl-/2-isothiocynato chitosan decanoate (3b) rather than the expected product N,N-(decanoyl)phenylthiocarbamoyl chitosan decanoate (3a). This result suggested that some of the N,N-(decanoyl)phenylthiocarmbamoyl groups had been converted to isothiocyanate groups during the decanoylation process. The subsequent reaction of compound 3b with aniline gave N,N-(decanoyl)phenylthiocarbamoyl/N-phenylthiocarbamoyl chitosan decanoate (4) in high yield. A solution of compound 4 in CHCl3 was then added to a solution of copper decanoate (5) in the same solvent, and the resulting mixture was cast onto a glass plate to give a cast film. The film was annealed at 200 °C in an oven to give a greenish film, which showed good near-infrared absorption characteristic in the range of 800–2200 nm. 相似文献
5.
6.
Per Henningsson Dirk Michaelis Toshiyuki Nakata Daniel Schanz Reinhard Geisler Andreas Schr?der Richard J. Bomphrey 《Journal of the Royal Society Interface》2015,12(108)
Particle image velocimetry has been the preferred experimental technique with which to study the aerodynamics of animal flight for over a decade. In that time, hardware has become more accessible and the software has progressed from the acquisition of planes through the flow field to the reconstruction of small volumetric measurements. Until now, it has not been possible to capture large volumes that incorporate the full wavelength of the aerodynamic track left behind during a complete wingbeat cycle. Here, we use a unique apparatus to acquire the first instantaneous wake volume of a flying animal''s entire wingbeat. We confirm the presence of wake deformation behind desert locusts and quantify the effect of that deformation on estimates of aerodynamic force and the efficiency of lift generation. We present previously undescribed vortex wake phenomena, including entrainment around the wing-tip vortices of a set of secondary vortices borne of Kelvin–Helmholtz instability in the shear layer behind the flapping wings. 相似文献
7.
Two dimensional standards are important materials which are used in the calibration and the verification of coordinate measuring machines. In several countries, the national metrology institutes or accredit laboratories provide the calibration services of the two dimensional standards such as ball plates, hole plates and grid plates. The metrological equivalence of the measurement standards among the calibration providers is validated through the key comparison program. In the previous key comparison for a ball plate and a hole plate, the equivalences among the participants’ calibration results were verified on the distances between the No. 1 ball/hole (i.e., the origins of the workpiece coordinates) and other balls/holes on the plates respectively. The essential measurands of the two dimensional standards are the coordinates of the feature points, however, the measurement equivalences on them have not been verified. In this study, the authors propose the coordinates-based evaluation of the reference values and their uncertainty in two dimensional standard calibration comparison. 相似文献
8.
D. Kasun Prasanga Kazuki Tanida Kouhei Ohnishi Toshiyuki Murakami 《Advanced Robotics》2019,33(15-16):824-839
ABSTRACTThis paper proposes a novel, simultaneous bipedal locomotion method using haptics for remote operation of biped robots. In general, traditional biped walking methods require very high computational power and advanced controllers to perform the required task. However, in this proposed method, a master exoskeleton attached to the human’s lower body is used to obtain the trajectory and haptic information to generate the trajectory of the slave biped robot in real time. Lateral motion of the center of mass of the biped is constrained in this experiment. Also, it is considered that no communication delay is presented in between the two systems in this experiment, and they are not discussed in this paper. Since a direct motion transmission is used in the proposed method, this method is quite straight forward and a simultaneous walking can be realized at the same time with high performance. Also, it does not require an exact dynamic model of the biped or specific method to plan the trajectory. The gait pattern of the biped is directly determined by that of the human. Also, the operator can feel the remote environment through the exoskeleton robot. Results obtained from the experiments validate the proposed method. 相似文献
9.
10.