全文获取类型
收费全文 | 13200篇 |
免费 | 317篇 |
国内免费 | 46篇 |
专业分类
电工技术 | 704篇 |
综合类 | 29篇 |
化学工业 | 3505篇 |
金属工艺 | 378篇 |
机械仪表 | 307篇 |
建筑科学 | 281篇 |
矿业工程 | 10篇 |
能源动力 | 545篇 |
轻工业 | 1100篇 |
水利工程 | 40篇 |
石油天然气 | 19篇 |
无线电 | 1149篇 |
一般工业技术 | 2301篇 |
冶金工业 | 1807篇 |
原子能技术 | 332篇 |
自动化技术 | 1056篇 |
出版年
2023年 | 75篇 |
2022年 | 164篇 |
2021年 | 316篇 |
2020年 | 129篇 |
2019年 | 160篇 |
2018年 | 195篇 |
2017年 | 153篇 |
2016年 | 247篇 |
2015年 | 194篇 |
2014年 | 323篇 |
2013年 | 605篇 |
2012年 | 523篇 |
2011年 | 677篇 |
2010年 | 570篇 |
2009年 | 596篇 |
2008年 | 652篇 |
2007年 | 543篇 |
2006年 | 483篇 |
2005年 | 423篇 |
2004年 | 383篇 |
2003年 | 427篇 |
2002年 | 372篇 |
2001年 | 284篇 |
2000年 | 284篇 |
1999年 | 280篇 |
1998年 | 784篇 |
1997年 | 501篇 |
1996年 | 372篇 |
1995年 | 263篇 |
1994年 | 260篇 |
1993年 | 241篇 |
1992年 | 156篇 |
1991年 | 169篇 |
1990年 | 100篇 |
1989年 | 154篇 |
1988年 | 92篇 |
1987年 | 120篇 |
1986年 | 111篇 |
1985年 | 138篇 |
1984年 | 113篇 |
1983年 | 110篇 |
1982年 | 115篇 |
1981年 | 100篇 |
1980年 | 82篇 |
1979年 | 79篇 |
1978年 | 80篇 |
1977年 | 87篇 |
1976年 | 104篇 |
1975年 | 39篇 |
1974年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Yurak Son Takuya Kamano Takashi Yasuno Takayuki Suzuki Hironobu Harada 《Electrical Engineering in Japan》2006,155(1):35-43
This paper describes the generation of adaptive gait patterns using new Central Pattern Generators (CPGs) including motor dynamic models for a quadruped robot under various environments. The CPGs act as the flexible oscillators of the joints and adjust joint angles to required values. The CPGs are interconnected with each other and sets of their coupling parameters are adjusted by a genetic algorithm so that the quadruped robot can realize stable and adequate gait patterns. Generation of gait patterns results in the formation of the CPG networks suitable for the formation of not only a straight walking pattern but also of rotating gait patterns. Experimental results demonstrate that the proposed CPG networks are effective for the automatic adjustment of the adaptive gait patterns for the tested quadruped robot under various environments. Furthermore, the target tracking control based on image processing is achieved by combining the general gait patterns. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 35–43, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20225 相似文献
33.
Kenji Asai Teruhiro Hatanaka Masaharu Tsubota Kunio Yonezu Koji Ando 《Journal of power sources》1985,16(1):65-73
In order to estimate the discharge performance of tall lead/acid cells (with tubular positives), changes in current and potential distributions with discharge progress were calculated with a computer on the basis of plate resistance and the current—potential—time relationship between small facing parts of positive and negative plates. The taller the cell, the larger the voltage drop along the plates. Thus, the discharge time became shorter despite a large amount of available active mass remaining in the bottom part of the plates.Various current-collector designs were evaluated, e.g., one with varying resistance at each height; a side conductor placed along the plates and connected to them at the top, centre and bottom, etc. Results revealed an optimum collector design with which the maximum discharge capacity could be obtained. Furthermore, it was shown that the side conductor markedly improved the discharge performance because the active mass near the connecting parts was appreciably used. 相似文献
34.
S Ito 《Canadian Metallurgical Quarterly》1993,41(4):451-455
There are a large number of ideas concerning the systematization of clinical laboratory management. Therefore many types of laboratory systems have been constructed. As our hospital is not large, we adopted a small scale laboratory system. In introducing it, we expected not only an increase in value-added labor productivity by automating laboratory tests, but also an improvement in technologist's cost awareness. Consequently, new system equipment has itself performed the former in many sections, but not the latter. Improvement in cost awareness was caused by the technologist's routine work in managing reagent and material stocks. We found that this soft-type systematization has been more important than the advanced hard-type system. 相似文献
35.
Activated ABL oncogenes cause B-cell leukemias in mice and chronic myelogenous leukemia in humans. However, the mechanism of transformation is complex and not well understood. A method to rapidly and reversibly activate c-ABL was created by fusing the extra-cytoplasmic and transmembrane domain of the erythropoietin (EPO) receptor with c-ABL (EPO R/ABL). When this chimeric receptor was expressed in Ba/F3 cells, the addition of EPO resulted in a dose-dependent activation of c-ABL tyrosine kinase and was strongly antiapoptotic and weakly mitogenic. To evaluate the contributions of various ABL domains to biochemical signaling and biological effects, chimeric receptors were constructed in which the ABL SH3 domain was deleted (triangle upSH3), the SH2 domain was deleted (triangle upSH2), the C-terminal actin-binding domain was deleted (triangle upABD), or kinase activity was eliminated by a point mutation, K290M (KD). The mutant receptors were stably expressed in Ba/F3 cells and analyzed for signaling defects, proliferation, viability, and EPO-induced leukemia in nude mice. When compared with the ability of the full-length EPO R/ABL receptor to induce proliferation and support viability in vitro, the triangle upSH3 mutant was equivalent, the triangle upSH2 mutant was moderately impaired, and the triangle upABD and KD mutants were profoundly impaired. None of these cell lines caused leukemia in mice in the absence of pharmacological doses of EPO. However, in mice treated with EPO (10 U/d), death from leukemia occurred rapidly with wild-type and triangle upSH3. However, time to death was prolonged by at least twofold for triangle upSH2 and greater than threefold for triangle upABD. This inducible model of ABL transformation provides a method to link specific signaling defects with specific biological defects and has shown an important role for the C-terminal actin-binding domain in proliferation and transformation in the context of this receptor/oncogene. 相似文献
36.
An integrated laser blood flowmeter 总被引:1,自引:0,他引:1
We have constructed a very small and lightweight blood flowmeter using micromachining and surface mounting techniques for a wearable health monitoring system. The hybrid integrated structure of the optical system incorporates a InGaAsP-InP distributed feedback laser diode (DFB-LD) with a wavelength of 1310 nm, an edge-illuminated photodiode (PD) and a polyimide waveguide on silicon substrate (2 mm /spl times/ 3 mm). This integrated flowmeter can be positioned directly on the tissue and permits real-time monitoring of capillary microcirculation. In-vivo measurements of blood perfusion in a finger confirm the feasibility of the blood flowmeter. 相似文献
37.
Masahito Matsubayashi Takashi Hibiki Kaichiro Mishima Koji Yoshii Koji Okamoto 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2003,510(3):325-333
A fluorescent converter for fast neutron radiography (FNR) comprising a scintillator and hydrogen-rich resin has been developed and applied to electronic imaging. The rate of the reaction between fast neutrons and the converter is increased by thickening the converter, but its opaqueness attenuates emitted light photons before they reach its surface. To improve the luminosity of a fluorescent converter for FNR, a novel type of converter was designed in which wavelength-shifting fibers were adopted to transport radiated light to the observation end face. The performance of the converter was compared with that of a polypropylene-based fluorescent converter in an experiment conducted at the fast-neutron-source reactor YAYOI in the University of Tokyo. 相似文献
38.
Matsugi J. Mizoh Y. Nakano T. Nakamura K. Sakakima H. 《Electronics Packaging Manufacturing, IEEE Transactions on》2005,28(3):206-212
It is well known that giant magnetoresistive (GMR) heads used for hard disk drives (HDD) are very sensitive to electrostatic discharge (ESD). In this paper, we describe a method of categorizing ESD damage modes from a standpoint of magnetic influences on the heads as observed by quasi-static test (QST) characteristics as well as electromagnetic characteristics like off-track profiles. In addition, we report an example of GMR stack interlayer diffusion which is one type of hard ESD damage. We also present an example of ESD damage that happened in an actual production process and its preventive measures as guidelines. 相似文献
39.
Susumu Onaka Masaharu Kato T. Mori 《Metallurgical and Materials Transactions A》1986,17(11):1949-1953
Steady-state sliding of grain boundaries is discussed by taking into account the change in the potential energy of an applied
stress, when the sliding occurs by diffusional accommodation. The present analysis enables us to derive the sliding rates
at boundaries of various shapes in a simple manner without knowing local stress fields. Sliding rate of a boundary containing
second phase particles is also derived by similar calculations. The results are compared with previous calculations by other
investigators, and it is found that the resultant expressions for the sliding rates are essentially identical to those derived
from more complex analyses. 相似文献
40.
Using the boundary element method, results of the push-pull ratio of differential output signals from an optical disc pregroove model by simulation are presented. The possibility of achieving higher information density by reducing the track pitch and the beam spot is demonstrated.<> 相似文献