全文获取类型
收费全文 | 4882篇 |
免费 | 82篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 239篇 |
综合类 | 2篇 |
化学工业 | 846篇 |
金属工艺 | 137篇 |
机械仪表 | 99篇 |
建筑科学 | 65篇 |
矿业工程 | 1篇 |
能源动力 | 137篇 |
轻工业 | 359篇 |
水利工程 | 15篇 |
无线电 | 574篇 |
一般工业技术 | 796篇 |
冶金工业 | 1280篇 |
原子能技术 | 104篇 |
自动化技术 | 319篇 |
出版年
2022年 | 33篇 |
2021年 | 58篇 |
2020年 | 26篇 |
2019年 | 24篇 |
2018年 | 48篇 |
2017年 | 50篇 |
2016年 | 86篇 |
2015年 | 58篇 |
2014年 | 77篇 |
2013年 | 184篇 |
2012年 | 158篇 |
2011年 | 180篇 |
2010年 | 127篇 |
2009年 | 171篇 |
2008年 | 169篇 |
2007年 | 128篇 |
2006年 | 122篇 |
2005年 | 133篇 |
2004年 | 99篇 |
2003年 | 115篇 |
2002年 | 113篇 |
2001年 | 117篇 |
2000年 | 108篇 |
1999年 | 152篇 |
1998年 | 506篇 |
1997年 | 293篇 |
1996年 | 253篇 |
1995年 | 152篇 |
1994年 | 139篇 |
1993年 | 129篇 |
1992年 | 64篇 |
1991年 | 70篇 |
1990年 | 59篇 |
1989年 | 47篇 |
1988年 | 59篇 |
1987年 | 49篇 |
1986年 | 46篇 |
1985年 | 50篇 |
1984年 | 60篇 |
1983年 | 53篇 |
1982年 | 46篇 |
1981年 | 49篇 |
1980年 | 54篇 |
1979年 | 35篇 |
1978年 | 31篇 |
1977年 | 29篇 |
1976年 | 48篇 |
1975年 | 15篇 |
1974年 | 24篇 |
1973年 | 13篇 |
排序方式: 共有4973条查询结果,搜索用时 15 毫秒
151.
152.
Toshihiko Hirama Masashi Goto Keiji Shiba Toshio Kobayashi Ryozo Tanaka Shizuo Tsurumaki Katsuki Takiguchi Hiroshi Akiyama 《Nuclear Engineering and Design》2005,235(13):7
A 1/8-scale model was constructed of a reinforced concrete containment vessel (RCCV) used in the latest advanced boiling water reactors (ABWR). Shaking table tests were conducted on it with input motions corresponding to or exceeding a design earthquake assumed for a real Nuclear Power Plant.The objectives of the tests were to verify the structural integrity and the leak-proof functional soundness of the RCCV subjected to design earthquakes, and to determine the ultimate strength and seismic margin by an excitation that led to the model's collapse. The model, the test sequence and the pressure and leak test results were addressed in Part 1. The shaking table test method, the input motions and the test results, including the transition of the model's stiffness, natural frequencies and damping factors and the effects of vertical input motions and internal pressure on the model's characteristics and behavior, the load–deformation, the ultimate strength, the failure mode of the reinforced concrete portion and the liner plate are described here. The seismic safety margin that was evaluated by the energy input during the failure test to a design basis earthquake will be described in Part 3. The analytical results of simulation using the multi-lumped mass model will be described in Part 4. 相似文献
153.
M. Kobayashi Y. Usuki M. Ishii M. Itoh M. Nikl 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2005,540(2-3):381-394
Since we presented our preliminary result (Nucl. Instr. and Meth. A 486 (2002) 170) at SCINT2001, we have continued our efforts to increase the light yield (LY) of PbWO4 scintillators by extending different dopings with an aim to find a possibility of using PbWO4 successfully in Positron Emission Tomography (PET). Overall result obtained for single doping as well as double and tripple co-dopings are summarized, including decay characteristics and radiation hardness. The LY in non-doped PbWO4 crystals with a size of 10×10×(20–30) mm3 is 25–35 photolectrons/MeV (phe/MeV) corresponding to 3–4% of the LY in BGO, when measured with a bialkali photomultiplier during a gate of 1 μs. The maximum LY increased to 49 phe/MeV for single doping with Mo6+, 80 phe/MeV for double co-doping of Mo6++Sb5+, and 85 phe/MeV for tripple co-doping of Mo6++Cd2++Sb5+. The radiation hardness is larger than 105 Gy for each of the samples co-doped with Mo6++Sb5+ and Mo6++Cd2++Sb5+, while it is much poorer in PWO:Mo6+. In each of these co-doped samples, a medium-speed green emission in the microsecond range is created besides the fundamental fast (a few nanoseconds range) blue one, giving a peak at 500 nm in the radioluminescence spectrum similarly as in PWO:Mo6+. 相似文献
154.
A quasi-particle (exciton-phonon polariton) model, as a simple model of an optical near-field probe, is proposed to investigate an unresolved problem in photochemical processes, i.e., why a vapor molecule can be dissociated by an incident photon with less energy than the dissociation energy only if, not a propagating far field, but an optical near field is used, and what is the mechanism leading to the photon flux dependence of the deposition rates. Incident photon energy and intensity dependences of Zn deposition rates are analyzed, and good agreement between the theoretical and experimental results is obtained. It suggests that the probe system plays an important role in vibrational transitions as well as electronic transitions in photodissociation processes, and that the couplings between the optical near field and molecular vibrations are enhanced to permit a nonresonant photodissociation inherent in the optical near field. 相似文献
155.
Nakano Hirofumi Ishizaka Kazuhisa Obata Motoki Kimura Keiji Kasahara Hironori 《International journal of parallel programming》2003,31(3):211-223
Effective use of cache memory is getting more important with increasing gap between the processor speed and memory access speed. Also, use of multigrain parallelism is getting more important to improve effective performance beyond the limitation of loop iteration level parallelism. Considering these factors, this paper proposes a coarse grain task static scheduling scheme considering cache optimization. The proposed scheme schedules coarse grain tasks to threads so that shared data among coarse grain tasks can be passed via cache after task and data decomposition considering cache size at compile time. It is implemented on OSCAR Fortran multigrain parallelizing compiler and evaluated on Sun Ultra80 four-processor SMP workstation using Swim and Tomcatv from the SPEC fp 95. As the results, the proposed scheme gives us 4.56 times speedup for Swim and 2.37 times on 4 processors for Tomcatv respectively against the Sun Forte HPC Ver. 6 update 1 loop parallelizing compiler. 相似文献
156.
Kobayashi M. Sawada R. Ueda Y. 《IEEE journal of selected topics in quantum electronics》2003,9(2):142-147
Ultraviolet laser diodes (UV-LD) were used for the excitation source of autofluorescence (AF) measurements and spectroscopic imaging of the AF originating from the human bronchus was obtained. The AF spectra from normal bronchus tissues were measured and a clear AF spectrum was obtained by using a short wavelength (400 nm) laser diode; the overlap of the AF signal and excitation source could be substantially eliminated. In order to study the origin of AF intensity deterioration from bronchus tissue due to the formation of tumor tissues, the fluorescence spectrum was measured for various AF substances under various conditions. The blue AF signal of elastin and NADH solutions, which could not be easily studied by conventional excitation light sources, as well as the green AF became weak by adding lactic acid. The AF spectrum was measured for 512/spl times/512 pixels and the intensity mapping as a function of emission wavelength was obtained. Two-dimensional information of the AF signal intensity distribution for a certain wavelength component was measured. The feature originating from a region as small as about 100 /spl mu/m could be recognized. Numerical calculations of the data were performed and precise features of the AF were revealed. 相似文献
157.
Diode-pumped tunable Yb:YAG miniature lasers at room temperature:modeling and experiment 总被引:3,自引:0,他引:3
Taira T. Saikawa J. Kobayashi T. Byer R.L. 《IEEE journal of selected topics in quantum electronics》1997,3(1):100-104
We present a simple design rule for diode-laser pumped quasi-three-level lasers by using the M2 factor. The validity of this model was demonstrated by diode-pumped Yb:YAG laser experiments. The maximum output power of 1.33 W and optical slope efficiency of 63% were obtained in a 400-μm Yb:YAG chip miniature laser. Using a 200-μm Yb:YAG chip, a 70% optical slope efficiency was reached. In a coupled-cavity configuration, with a quartz birefringent tuning filter, 8.2 THz (29 nm) of tuning was obtained at room temperature. By changing to a calcite birefringent filter, single-axial-mode oscillation with an output power of 500 mW was observed 相似文献
158.
Kobayashi H. Yamamoto T. Ekawa M. Watanabe T. Ishikawa T. Fujii T. Soda H. Ogita S. Kobayashi M. 《IEEE journal of selected topics in quantum electronics》1997,3(6):1384-1391
This paper describes the optimum design, fabrication, and performance of a 1.3-μm multiple-quantum-well (MQW) laser diode monolithically integrated with a tapered thickness spot-size transformer. The dependence of the lasing characteristics on the thickness distribution of the core layer and on the current injection profile of the device were analyzed. This integrated laser with its optimized structure performed at a low threshold current of 22.2 mA, even at 85°C. The integrated spot-size transformer effectively reduced the lateral and vertical far-field FWHM's to 8° and 9°, respectively. A very long lifetime of over 1×105 h was estimated at 85°C and 8 mW under CW operation 相似文献
159.
Sensor Fusion System Using Recurrent Fuzzy Inference 总被引:1,自引:0,他引:1
Futoshi Kobayashi Fumihito Arai Toshio Fukuda Koji Shimojima Makoto Onoda Norimasa Marui 《Journal of Intelligent and Robotic Systems》1998,23(2-4):201-216
In robotic and manufacturing systems, it is difficult to measure the state of systems accurately because of many uncertain factors and noise, and it is very important to estimate the state of systems. We must measure the phenomena of systems by multiple sensors and estimate the state of systems by acquiring information of sensors. However, we can not acquire all of sensor information synchronically, because each sensor has particular sensor information and measuring time. For estimating the state of systems by multiple sensors, a multi-sensor fusion system fusing various sensory information is needed. In this paper, we propose a Recurrent Fuzzy Inference (RFI) with recurrent inputs and apply it to a multi-sensor fusion system for estimating the state of systems. The membership functions of RFI are expressed by Radial Basis Function (RBF) with insensitive ranges. The shape of the membership functions can be adjusted by a learning algorithm. The learning algorithm is based on the steepest descent method and incremental learning which can add new fuzzy rules. The effectiveness of the multi-sensor fusion system using RFI will be shown through a numerical experiment of moving robot and estimation of surface roughness in grinding process. 相似文献
160.
It is known that an adaptive controller via high-gain output feedback can globally stabilize a class of minimum phase systems with relative degree one. However, exact output regulation is difficult for systems with disturbances. In this paper, we consider linear single-input/single-output (SISO) systems with unknown constant disturbances. We present a simple adaptive output feedback controller with an integral action and show that it can asymptotically stabilize those disturbed systems. The proposed PI type adaptive controller can also deal with the output tracking problem of a step reference 相似文献