首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   311篇
  免费   19篇
电工技术   19篇
综合类   1篇
化学工业   49篇
金属工艺   5篇
机械仪表   4篇
建筑科学   1篇
能源动力   7篇
轻工业   23篇
无线电   43篇
一般工业技术   72篇
冶金工业   79篇
原子能技术   4篇
自动化技术   23篇
  2023年   2篇
  2022年   5篇
  2021年   3篇
  2020年   6篇
  2019年   4篇
  2018年   5篇
  2017年   7篇
  2016年   7篇
  2015年   6篇
  2014年   12篇
  2013年   16篇
  2012年   17篇
  2011年   14篇
  2010年   9篇
  2009年   13篇
  2008年   10篇
  2007年   11篇
  2006年   8篇
  2005年   7篇
  2004年   11篇
  2003年   6篇
  2002年   5篇
  2001年   9篇
  2000年   8篇
  1999年   10篇
  1998年   27篇
  1997年   17篇
  1996年   16篇
  1995年   6篇
  1994年   6篇
  1993年   7篇
  1992年   3篇
  1990年   3篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   5篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1978年   2篇
  1977年   3篇
  1976年   1篇
  1973年   4篇
  1971年   1篇
排序方式: 共有330条查询结果,搜索用时 15 毫秒
91.
For an ATM switch system, we have developed a 100-Gb/s input/output (I/O) throughput optical I/O interface ATM switch multichip module (MCM) that has 320-ch optical I/O ports. This MCM is fabricated using ceramic (MCM-C) technology and very-small highly-parallel O/E and E/O optical converters. It uses 0.25-μm complementary metal oxide semiconductors (CMOS) ATM switch large scale integrations (LSIs) and has a total I/O throughput of up to 160 Gb/s. A prototype module with total I/O throughput of 100 Gb/s has been partially assembled using eight optical I/O interface blocks, each composed of a 40-ch O/E converter and a 40-ch E/O converter; the data rate per channel is from dc to 700 Mb/s. Using this module we developed an optical I/O interface ATM switch system and confirmed the operation of the optical interface  相似文献   
92.
Metal–ceramic composite pipes were prepared through simultaneous extrusion of different pastes by a multi-billet extrusion method. ZrO2 and stainless steel powders were chosen, and an aqueous solution of water-soluble polymer, hydroxypropyl methylcellulose (HPMC), was used as binder. The maximum extrusion pressure and the minimum amount of binder required reached their lowest values when the mixing fraction of ZrO2 powder was 0.4. The minimum amount of binder for forming the outer layers was 4%–5% higher than that for inner layers, even for the same powder. It was possible to decrease the binder content and broaden the extrudable range of the binder content by means of mixing coarse and fine powders.  相似文献   
93.
Plastics and fiber-reinforced plastics (FRP) are used in the aerospace industry because of their mechanical properties. However, despite their excellent high-temperature mechanical properties, plastics and FRP eventually deform visco-elastically at high temperatures. Most of the research has focused on the creep behavior of FRPs, but few studies have investigated the linear visco-elastic behavior. Linear visco-elastic behavior and non-linear visco-elastic behavior occur with physical aging in these plastics. In this study, the non-linear visco-elastic behavior of plastics and FRP was investigated based on the bending creep deformation of polycarbonate (PC) and polyoxymethylene (POM). Moreover, the effects of the fiber volume fraction on the creep characteristics were investigated using glass fiber-reinforced polycarbonate (GFRPC). The creep deformation was calculated using the linear visco-elastic theory based on these effects, and comparison between experimental and estimated data showed that the creep analysis sufficiently predicted the creep behavior.  相似文献   
94.
95.
A hybrid-guiding tellurite (TZNLP) photonic bandgap fiber (PBGF) with low confinement loss is presented in this paper. A detailed comparison between the hybrid-guiding tellurite PBGF in which the high-index rods (TLWMN) replace one row of air holes in the radial direction and the all-solid tellurite PBGF has been accomplished. Low confinement loss windows can be achieved in this novel fiber due to the collaborated action of two guiding mechanisms–total internal reflection and antiresonant reflection.  相似文献   
96.
Song Y  Sakai J  Saito A  Usui M  Azakami H  Kato A 《Die Nahrung》2002,46(3):209-213
The relationship between the stability of lysozymes mutated at the inside hydrophobic core and secretion was investigated to understand the optimal secretion of mutant lysozymes in the Saccharomyces cerevisiae. S91T mutant lysozyme increased in the methyl residue inside the core greatly increased the conformational stability. The secretion amount of S91T in S. cerevisiae increased greatly compared with wild-type lysozyme. On the other hand, I55V and T40S/I55V mutant lysozymes decreased in methyl residue inside the core brought about their unstable conformation. The secretion amounts of these unstable mutant lysozymes significantly decreased. In addition, the effect of glycosylation on the secretion of these mutants was investigated. The secretion amounts of glycosylated lysozyme S91T/G49N with stable hydrophobic core greatly increased compared with that of glycosylated lysozyme G49N, while those of mutant I55V/G49N and T40S/I55V/G49N with unstable hydrophobic core greatly decreased. These results indicate that the secretion amounts of mutant lysozymes increase in proportion to the hydrophobic core stabilities and that a similar good correlation was obtained with glycosylated lysozymes.  相似文献   
97.
Neutral beam (NB) injectors for JT-60 Super Advanced (JT-60SA) have been designed and developed. Twelve positive-ion-based and one negative-ion-based NB injectors are allocated to inject 30 MW D0 beams in total for 100 s. Each of the positive-ion-based NB injector is designed to inject 1.7 MW for 100 s at 85 keV. A part of the power supplies and magnetic shield utilized on JT-60U are upgraded and reused on JT-60SA. To realize the negative-ion-based NB injector for JT-60SA where the injection of 500 keV, 10 MW D0 beams for 100 s is required, R&Ds of the negative ion source have been carried out. High-energy negative ion beams of 490–500 keV have been successfully produced at a beam current of 1–2.8 A through 20% of the total ion extraction area, by improving voltage holding capability of the ion source. This is the first demonstration of a high-current negative ion acceleration of >1 A to 500 keV. The design of the power supplies and the beamline is also in progress. The procurement of the acceleration power supply starts in 2010.  相似文献   
98.
The internal quantum efficiencies under sunlight and laser excitation were measured directly by an integrating sphere method for tellurite, borosilicate and fluoride glasses. The radiative quantum efficiency was also obtained by Judd–Ofelt analysis. The radiative quantum efficiency was almost 100% for tellurite and fluoride glasses and 50% for borosilicate glasses. The quantum efficiency under laser excitation was 86%, 34% and 88% for tellurite, borosilicate and fluoride glasses at a low Nd3+ content and decreased by concentration quenching. The quantum efficiency under sunlight excitation was up to 33%, 21% and 70% for tellurite, borosilicate and fluoride glasses. Nd3+-doped fluoride glass is a promising candidate for solar pumped laser applications since it has the high quantum efficiency under sunlight excitation.  相似文献   
99.
We have studied effects of photodynamic diagnosis (PDD) and photodynamic therapy (PDT) in hepatoma as confirmed by the existence of hepatoma when using a new photosensitizer mono-L-aspartyl chlorin e6. Japanese white rabbits were selected to perform abdominal incision under intravenous anesthesia and transplant VX2 tumor cells into the liver left lobe for the hepatoma model. Hepatoma of 1 cm in diameter (at one week after transplantation) was used experimentally to radiate a semiconductor laser (664 nm, 200 J/cm2) for treatment.  相似文献   
100.
A 41-year-old male with myelomenigocele underwent a bladder auto-augmentation and endoscopic collagen injections. He has been performing self intermittent catheterization for 10 years but urinary incontinence remained unchanged. Furthermore, he suffered from recurrent pyelonephritis due to the left vesicoureteral reflux. A preoperative fluoroscopic urodynamic study showed a poorly compliant bladder with the maximal bladder capacity of 200 ml at 60 cmH2O. The left vesicoureteral reflux was observed at 10 cmH2O. The low compliant bladder was treated with the bladder autoaugmentation and the left vesicoureteral reflux was treated with the endoscopic subureteral injection of collagen 5 months after the previous operation. A fluoroscopic urodynamic study 6 months postoperatively showed the increase of the maximal bladder capacity of 300 ml at 18 cmH2O and the reflux disappeared completely. The endoscopic periurethral injections of collagen improved his persisting urinary incontinence. In patient with neurogenic bladder having a lot of clinical problems, bladder auto-augmentation is less invasive and offers many advantages over enterocystoplasy.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号