全文获取类型
收费全文 | 728篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 53篇 |
综合类 | 2篇 |
化学工业 | 133篇 |
金属工艺 | 27篇 |
机械仪表 | 14篇 |
建筑科学 | 20篇 |
矿业工程 | 2篇 |
能源动力 | 33篇 |
轻工业 | 30篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 71篇 |
一般工业技术 | 136篇 |
冶金工业 | 154篇 |
原子能技术 | 25篇 |
自动化技术 | 48篇 |
出版年
2023年 | 11篇 |
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 24篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 20篇 |
2013年 | 47篇 |
2012年 | 33篇 |
2011年 | 49篇 |
2010年 | 33篇 |
2009年 | 34篇 |
2008年 | 39篇 |
2007年 | 20篇 |
2006年 | 30篇 |
2005年 | 23篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 69篇 |
1997年 | 31篇 |
1996年 | 25篇 |
1995年 | 5篇 |
1994年 | 17篇 |
1993年 | 22篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有751条查询结果,搜索用时 15 毫秒
31.
Yongsheng Liu Hidetoshi Kita Kazuhiro Tanaka Kota Imawaka Shunsuke Tanaka Takahiko Takewaki 《应用聚合物科学杂志》2021,138(16):50251
The mixed matrix membranes (MMMs) consisting zeolitic-imidazolate framework-8 (ZIF-8) nanoparticles in a polymer have been of considerable interest in separation applications. The fillers used are mostly synthesized using the solvothermal method. In this study, the ZIF-8 nanoparticles were synthesized using a solvent-less and salt-free mechanochemical method and were added to 6FDA-TrMPD polyimide to prepare MMMs. The single gas permeation of C3H6 and C3H8 through the MMMs was investigated. The C3H6 permeability and C3H6/C3H8 ideal selectivity of a 20 wt% mechano-synthesized ZIF-8/6FDA-TrMPD MMM were 70% and 32% higher than those of the neat polymer membrane at 0.1 MPa and 308 K, respectively. The C3H6/C3H8 separation performance of the mechano-synthesized ZIF-8 MMM was similar to that of the conventional solvothermal-synthesized ZIF-8 MMM. This separation performance was in good agreement with the Maxwell model. Temperature and pressure dependence analyses confirmed that the mechano-synthesized ZIF-8 nanoparticles acted as molecular sieves in the MMMs for the C3H6 and C3H8 permeation. 相似文献
32.
Surface of an InAs wetting layer on GaAs(001) preceding InAs quantum dot (QD) formation was observed at 300°C with in situ scanning tunneling microscopy (STM). Domains of (1 × 3)/(2 × 3) and (2 × 4) surface reconstructions were located in the STM image. The density of each surface reconstruction domain was comparable to that of subsequently nucleated QD precursors. The distribution of the domains was statistically investigated in terms of spatial point patterns. It was found that the domains were distributed in an ordered pattern rather than a random pattern. It implied the possibility that QD nucleation sites are related to the surface reconstruction domains. 相似文献
33.
34.
Toru Nakajima Kazuyoshi Shiba Kazuya Tamegaya Kiyokazu Tsukamoto 《Welding International》2013,27(10):752-758
Recently, the electron beam welders with high acceleration voltage (more than 100 kV) and high electrical power (more than 15 kW) have been reviewed the role of the high-energy electron beam density again, due to space or aircraft development or automobile industry desired high productivity and high accurate welding for saving energy. NEC group have supplied these electron beam welders. This time, the automatic alignment adjustment system of the electron beam orbit and the automatic adjustment system of filament current were developed and put to a practical use. As a result, the great effectiveness for the stability of welding quality was apparent. 相似文献
35.
This paper describes the effect of a passive EMI filter on preventing bearing current from flowing inside an inverter‐driven motor. Motor‐bearing damage is often caused by bearing currents resulting from the breakdown of grease films in the motor bearing. The high‐frequency common‐mode voltage generated by the PWM inverter induces a shaft voltage between the rotor and the frame. When the shaft voltage exceeds the breakdown voltage of the grease films, a destructive instantaneous discharge current with a peak value of about 1 A flows through the motor bearing. The passive EMI filter, which is unique in access to the motor neutral line, can reduce the shaft voltage as a result of eliminating the high‐frequency common‐mode voltage from the motor terminals. Hence, no breakdown occurs in the grease film, so that no bearing current flows. The viability and effectiveness of the passive EMI filter is verified by experimental results obtained from a 400‐V, 3.7‐kW laboratory system. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 78– 87, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20489 相似文献
36.
Masuda Senichi Hosokawa Shunsuke Tachibana Naoji Ando Takashi Matsumoto Yoichi 《Industry Applications, IEEE Transactions on》1987,(1):120-126
The fundamental characteristics of the direct-coupled pulse energization in electrostatic precipitators (EP's) are investigated in a test rig comprised of a coal pulverizing facility, a furnace, a gas cooling system, and an EP. The EP consisted of a corona electrode with barbed wires and a collection electrode with 300-mm duct spacing. This simulates the type of EP normally used in a coal-fired power station. The pulse-energized collection field shows a very high collection performance of more than 99 percent collection efficiency and the performance enhancement compared to the conventional dc energization, causing very severe back corona, becomes as large as H = 2.50.H is the enhancement factor in terms of the Deutsch migration velocity in the case of the very high resistivity dust of rd = 2 x 1013 ?cm at the gas temperature of Tg = 150°C. Even at the lower level of the dust resistivity at Tg = 110°C, where no back corona occurs in the dc-energized collection field, the performance enhancement is as large as H = 1.21. The mechanism of such great performance enhancement is likely to be the result of the very uniform and very intense formation of corona plasmas on the wires as a result of the very fast rise in the pulse voltage applied and a special sawtooth waveform of the operating voltage between the corona and collection electrodes. 相似文献
37.
Yasushi Sakurai Masatoshi Yoshikawa Shunsuke Uemura Haruhiko Kojima 《The VLDB Journal The International Journal on Very Large Data Bases》2002,11(2):93-108
We propose a novel index structure, the A-tree (approximation tree), for similarity searches in high-dimensional data. The
basic idea of the A-tree is the introduction of virtual bounding rectangles (VBRs) which contain and approximate MBRs or data
objects. VBRs can be represented quite compactly and thus affect the tree configuration both quantitatively and qualitatively.
First, since tree nodes can contain a large number of VBR entries, fanout becomes large, which increases search speed. More
importantly, we have a free hand in arranging MBRs and VBRs in the tree nodes. Each A-tree node contains an MBR and its children
VBRs. Therefore, by fetching an A-tree node, we can obtain information on the exact position of a parent MBR and the approximate
position of its children. We have performed experiments using both synthetic and real data sets. For the real data sets, the
A-tree outperforms the SR-tree and the VA-file in all dimensionalities up to 64 dimensions, which is the highest dimension
in our experiments. Additionally, we propose a cost model for the A-tree. We verify the validity of the cost model for synthetic
and real data sets.
Edited by T. Sellis. Received: December 8, 2000 / Accepted: March 20, 2002 Published online: September 25, 2002 相似文献
38.
K Itoh E Tsukamoto T Mochizuki K Kanegae C Katoh N Tamaki 《Canadian Metallurgical Quarterly》1998,35(8):689-695
We compared relationship among three single blood sampling methods which have been proposed for determination of plasma clearance with 99mTc-MAG3. Russell's and Bubeck's algorithms were employed for 48 adults (average age: 53 years) and Bubeck's and Piepsz's algorithms were used in 9 children (average age: 5.8 years). Three methods showed very high correlation among them. However, Russell's and Piepsz's methods were about 1.4 times higher than Bubeck's method in calculating plasma clearance of 99mTc-MAG3. The present study indicates that three methods discussed here are useful for the determination of plasma clearance with 99mTc-MAG3. In addition, Bubeck's method may be preferable as a reference for single plasma sampling method because of common application to adults and children. 相似文献
39.
40.
K Shitoh F Konishi S Masubuchi S Senba T Tsukamoto K Kanazawa 《Canadian Metallurgical Quarterly》1998,28(9):538-541
PURPOSE: Our purpose was to assess the value of monitoring serum P and inhibin A to determine how values might improve the clinical monitoring of natural cycle in vitro fertilization (IVF)-embryo transfer (ET) patients. METHODS: All patients (n = 26) who underwent natural-cycle IVF-ET (n = 35) were analyzed. Groups were evaluated according to patients who had a spontaneous luteinizing hormone (LH) surge (group I) and women receiving human chorionic gonadotropin (hCG) who underwent subsequent oocyte aspiration (group II). Group II was further evaluated according to women who did (n = 10) and did not (n = 7) have an ET. All cycles were evaluated with serial transvaginal ultrasonography and serum estradiol, progesterone, and inhibin A. When follicle maturity was achieved, hCG, 10,000 IU, was administered intramuscularly if a LH surge was not detected. Transvaginal ultrasound-guided aspiration was performed 34-36 hr after hCG administration followed by a 48-hr transcervical ET. RESULTS: No differences were seen in cycles the day prior to (d-1) and the day of a spontaneous LH surge, (n = 18) or hCG (d-0)(n = 17) in group I or group II with respect to lead follicular diameter (d-1, 15.3 +/- 0.6 vs. 14.2 +/- 0.9 mm; d-0, 17.4 +/- 0.8 vs. 17.8 +/- 0.6 mm) and serum estradiol (d-1, 148 +/- 15 vs. 150 +/- 15 pg/ml; d-0, 218 +/- 15 vs. 199 +/- 16 pg/ml), respectively. However, serum progesterone was significantly elevated in group I compared with group II on d-1 (0.82 +/- 0.6 vs. 0.48 +/- 0.04 ng/ml; P < 0.05) and d-0 (1.1 +/- 0.12 vs. 0.63 +/- 0.08 ng/ml; P < 0.05). Inhibin A was significantly greater on d-1 in group I (24 +/- 2.5 vs. 15 +/- 2.2 pg/ml; P < 0.05). In group II, cycles that resulted in an ET (n = 10) compared with group II cycles that did not (n = 7) revealed a significant difference in serum progesterone (0.51 +/- 0.05 vs. 0.7 +/- 0.07 ng/ml; P < 0.05) and inhibin A (15 +/- 2.5 vs. 37.3 +/- 5 pg/ml; P < 0.05) the day of hCG. CONCLUSIONS: The possible application of serum progesterone and inhibin A in managing natural-cycle IVF-ET is suggested. These assays may predict women who should be set up for egg retrieval, while cancelling others in spite of the absence of an LH surge. 相似文献