全文获取类型
收费全文 | 3387篇 |
免费 | 63篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 130篇 |
综合类 | 2篇 |
化学工业 | 649篇 |
金属工艺 | 107篇 |
机械仪表 | 63篇 |
建筑科学 | 55篇 |
能源动力 | 124篇 |
轻工业 | 261篇 |
水利工程 | 7篇 |
石油天然气 | 5篇 |
无线电 | 382篇 |
一般工业技术 | 524篇 |
冶金工业 | 838篇 |
原子能技术 | 80篇 |
自动化技术 | 231篇 |
出版年
2023年 | 11篇 |
2022年 | 30篇 |
2021年 | 48篇 |
2020年 | 30篇 |
2019年 | 23篇 |
2018年 | 44篇 |
2017年 | 28篇 |
2016年 | 39篇 |
2015年 | 31篇 |
2014年 | 51篇 |
2013年 | 174篇 |
2012年 | 89篇 |
2011年 | 131篇 |
2010年 | 113篇 |
2009年 | 97篇 |
2008年 | 151篇 |
2007年 | 110篇 |
2006年 | 101篇 |
2005年 | 103篇 |
2004年 | 109篇 |
2003年 | 89篇 |
2002年 | 87篇 |
2001年 | 68篇 |
2000年 | 67篇 |
1999年 | 88篇 |
1998年 | 303篇 |
1997年 | 228篇 |
1996年 | 148篇 |
1995年 | 94篇 |
1994年 | 90篇 |
1993年 | 90篇 |
1992年 | 49篇 |
1991年 | 43篇 |
1990年 | 47篇 |
1989年 | 37篇 |
1988年 | 34篇 |
1987年 | 35篇 |
1986年 | 24篇 |
1985年 | 35篇 |
1984年 | 44篇 |
1983年 | 27篇 |
1982年 | 31篇 |
1981年 | 34篇 |
1980年 | 32篇 |
1979年 | 24篇 |
1978年 | 16篇 |
1977年 | 15篇 |
1976年 | 28篇 |
1975年 | 10篇 |
1972年 | 7篇 |
排序方式: 共有3458条查询结果,搜索用时 0 毫秒
21.
T Kimura I Haruta Y Isobe E Ueno J Toda Y Nemoto K Ishikawa Y Miyazono K Shimizu K Yamauchi N Hayashi 《Canadian Metallurgical Quarterly》1997,92(5):883-886
We present a patient with continuous melena, diagnosed as rectal varices bleeding. She had a history of esophageal varices, which was treated by endoscopic ligation therapy. Eight years after the treatment of esophageal varices, the continuous melena began. Colonoscopic examination showed that the melena was caused by rectal varices, which were so severe that they could not be treated by either endoscopic sclerotherapy or surgical devascularization. Taking into considering the overall risk of treating rectal varices, we chose the approach of double balloon-occluded embolotherapy (DBOE) with 5% ethanolamine oleate with iopamodol as a liquid embolic material. DBOE is one of the interventional radiology techniques (Morita et al., Acta Hepatol Jpn 1994;35:109-120), but in this case was a completely new and novel clinical procedure for rectal varices. After the DBOE therapy, the condition of rectal varices was markedly improved. Thus, DBOE might be a new tool for treating inoperable rectal varices. 相似文献
22.
Melt crystallization of isotactic polypropylene (iPP), containing crystallites of N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide (DCNDCA) as a nucleating agent of the the β-phase iPP crystal, is carried out under a magnetic field (6 T) to obtain the alignment of the iPP crystal induced by magnetic alignment of DCNDCA. In a previous paper, DCNDCA was reported to undergo magnetic alignment in a liquid suspension. The obtained iPP sample exhibits alignment of the β-phase crystal with the c-axis aligned perpendicular to the magnetic field. The comparison of this alignment of iPP with the reported magnetic alignment of DCNDCA indicates that the β-phase crystal grows epitaxially on the DCNDCA crystal. The (330)β plane of the iPP crystal lies on the bc-plane of the DCNDCA crystal in which the direction of the c-axis of the iPP coincides with the direction of the b-axis of the DCNDCA crystal. 相似文献
23.
I Hirata S Kimura T Michihata H Osawa M Kume T Kashima 《Canadian Metallurgical Quarterly》1997,45(8):1173-1177
A 66-year-old male with Beh?et's disease admitted again with hemoptysis. He underwent the resection and direct closure of descending aortic aneurysm 3 years ago, followed without the use of steroid. Chest CT scanning demonstrated a recurrent aneurysm of the descending aorta which was could not be detected on the previous CT only 23 days before. In the current operation, we performed resection, direct closure and wrapping of the aneurysm. The pathological examination showed a true aneurysm of Beh?et's disease. The patient is free from recurrence for 17 months since the operation under steroid therapy. 相似文献
24.
Effective double layer structure was investigated by adding Nb to the sputtering source of Co-Cr thin film perpendicular magnetic recording tapes. The output from the tapes was measured with a ring head through to the short wavelength, λ50 =0.19 μm (D50 =267KFRPI). 相似文献
25.
Chemically derived epitaxial thin films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) are fabricated on [001]LaAlO/sub 3/ substrates by the metalorganic-deposition (MOD) process, which has advantages of high quality, nonvacuum, low-cost, and large-scale production of high-T/sub c/ superconducting films. The MOD-derived YBCO films have a sharp transition at the critical temperature (90.4 K) and a high-quality film with a surface resistance of 0.13 m/spl Omega/ (30 K, 9.98 GHz) is obtained. As a microwave application, simple and compact bandpass filters (BPFs) using /spl lambda//4 coplanar-waveguide. stepped-impedance resonators are demonstrated on the YBCO films. A two-stage Chebyshev BPF of center frequency of 5.731 GHz, bandwidth of 135 MHz, and insertion loss of 0.29 dB with little input power dependency in a power range less than 10 dBm is realized on the film. 相似文献
26.
The effect of plasma elongation on the second‐stable spherical tokamak (ST) was numerically studied using the experimentally measured pressure and current profiles of ultrahigh‐beta STs. The maximum beta of ST over 50% was obtained in the TS‐3 ST/CT experiment by applying an external toroidal field to an FRC. It was found that the marginal beta for the ballooning instability increased with the plasma elongation κ of ST. The elongated STs with κ > 2 have the magnetic shear (S)–pressure gradient (α) profiles located in the second‐stable regime for the ballooning mode and the stability margin increased with κ. The close relation between the absolute minimum‐B profile and the second stability was documented. The effect of elongation on maximum beta was observed to saturate when κ exceed 3, indicating that the optimized elongation for high‐beta STs is located around 2 < κ < 3. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 1–6, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20132 相似文献
27.
The author have developed compact optical isolators operating at 480 nm wavelength with an insertion loss of 1.0 dB, isolation of 30 dB, size of 4φ×4.5 mm and endurance against laser power of ~500 mW using Cd1-x-yMnxHgyTe single crystals for the first time 相似文献
28.
Nakamura K. Kuhara S. Kimura T. Takada M. Suzuki H. Yoshida H. Yamazaki T. 《Solid-State Circuits, IEEE Journal of》1994,29(11):1317-1322
This 512 Kw×8 b×3 way synchronous BiCMOS SRAM uses a 2-stage wave-pipeline scheme, a PLL self-timing generator and a 0.4-μm BiCMOS process to achieve 220 MHz fully-random read/write operations with a GTL I/O interface. Newly developed circuit technologies include: 1) a zig-zag double word-line scheme, 2) a centered bit-line load layout scheme, and 3) a phase-locked-loop (PLL) with a multistage-tapped ring oscillator which generates a clock cycle proportional pulse (CCPP) and a clock edge lookahead pulse (CELP) 相似文献
29.
Hisamoto D. Nakamura K. Saito M. Kobayashi N. Kimura S. Nagai R. Nishida T. Takeda E. 《Electron Devices, IEEE Transactions on》1994,41(5):745-750
This paper describes a new ultra-thin SOI-CMOS structure offering reduced parasitic diffusion-layer resistance. It addresses ways to deal with the ultra-shallow junctions required by sub-0.1 μm MOSFET's. Based on a CVD tungsten process we experimentally investigate the characteristics of selectively grown tungsten used in the source and drain region made in SOI layers of various thicknesses ranging from 10 to 100 nm. We also investigate certain CMOS device characteristics. The SOI-CMOS structure, with low parasitic diffusion-layer resistance and good contact characteristics for ultra-shallow junction devices exhibits superior device performance and high scalability 相似文献
30.