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   411篇
  免费   19篇
  国内免费   1篇
电工技术   22篇
综合类   1篇
化学工业   86篇
金属工艺   12篇
机械仪表   10篇
建筑科学   6篇
能源动力   16篇
轻工业   46篇
水利工程   2篇
石油天然气   1篇
无线电   28篇
一般工业技术   78篇
冶金工业   87篇
原子能技术   2篇
自动化技术   34篇
  2023年   2篇
  2022年   2篇
  2021年   7篇
  2020年   10篇
  2019年   5篇
  2018年   11篇
  2017年   4篇
  2016年   9篇
  2015年   6篇
  2014年   9篇
  2013年   18篇
  2012年   20篇
  2011年   18篇
  2010年   15篇
  2009年   16篇
  2008年   16篇
  2007年   11篇
  2006年   12篇
  2005年   17篇
  2004年   10篇
  2003年   10篇
  2002年   9篇
  2001年   6篇
  2000年   4篇
  1999年   12篇
  1998年   33篇
  1997年   17篇
  1996年   10篇
  1995年   15篇
  1994年   8篇
  1993年   6篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1989年   4篇
  1988年   4篇
  1987年   5篇
  1986年   5篇
  1985年   7篇
  1984年   3篇
  1982年   4篇
  1981年   9篇
  1980年   2篇
  1979年   8篇
  1978年   2篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1974年   3篇
  1968年   2篇
排序方式: 共有431条查询结果,搜索用时 31 毫秒
41.
A study was carried out to see if the potential of renewable energy sources other than hy droelectric power, such as wind, photovoltaic, solar thermal, biomass and waste energy sources, can meet the current energy consumption in Yakushima. The current electricity consumption can be covered by wind and photovoltaic energy sources. The total potential of wind and photovoltaic energy sources is 5.4 times as much as the current electricity consumption. LP gas and kerosene can be replaced by solar thermal and biogas energy. The potential of plant biomass and municipal waste is not sufficient (approximately one third) to cover the rest of the fossil fuels (gasoline, diesel oil and heavy oil). Also, plant biomass and municipal waste must be converted into fluid form. This shortage can be covered by the po tential of wind and photovoltaic energy sources. We also investigated the possibility of tourism expansion using the potential of wind and photovoltaic energy sources. Taking into account three types of capacity (energy, accommodation and transportation), Yakushima can accept approximately four times as many tourists as the current number of tourists.  相似文献   
42.
We report on the direct deposition of high-quality ZrO2 thin films on various kinds of substrates by the liquid phase deposition method. After reaction for 24 h, thin films formed on various kinds of substrates, and the obtained thin film was comprised of densely packed nano-sized particles. The film annealed at 500°C showed a tetragonal phase at room temperature and this phenomenon has been discussed from the viewpoint of crystallite size effect. The result of optical transmittance measurement revealed that high transparency, more than 70% transmittance, has been achieved for the film after annealing at 900°C.  相似文献   
43.
This paper describes the effect of mutual leakage reactance in the rotor circuit on the analysis of generator transient characteristics. The authors derive a detailed equivalent circuit model for a 48P‐15,750‐kVA generator, analyze sudden short circuits and asynchronization phenomena of the generator by simulations with an electromagnetic transients program (ATP‐EMTP), and compare the results with experimental data. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 31–40, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20147  相似文献   
44.
The Philadelphia chromosome translocation generates a chimeric oncogene, BCR/ABL, which causes chronic myelogenous leukemia (CML). In primary leukemic neutrophils from patients with CML, the major tyrosine phosphorylated protein is CRKL, an SH2-SH3-SH3 adapter protein which has an overall homology of 60% to CRK, the human homologue of the v-crk oncogene. In cell lines transformed by BCR/ABL, CRKL was tyrosine phosphorylated, while CRK was not. We looked for changes in CRK- and CRKL-binding proteins in Ba/F3 hematopoietic cell lines which were transformed by BCR/ABL. Anti-CRK II or anti-CRKL immunoprecipitates were probed by far Western blotting with CRK II- or CRKL-GST fusion proteins to display CRK- and CRKL-coprecipitating proteins. There was a striking qualitative difference in the proteins coprecipitating with CRKL and CRK II. In untransformed cells, three major proteins coprecipitated with CRKL, identified as C3G, SOS and c-ABL. Each of these proteins was found to interact with the CRKL-SH3 domains, but not the SH2 domain. After BCR/ABL transformation, the CRKL SH3-domain binding proteins did not change, with the exception that BCR/ABL now coprecipitated with CRKL. Compared to CRKL, very few proteins coprecipitated with CRK II in untransformed, quiescent cells. After BCR/ABL transformation, both the CRKL- and CRK-SH2 domains bound to a new complex of proteins of approximate molecular weight 105-120 kDa. The major protein in this complex was identified as p120CBL. Thus, in these hematopoietic cell lines, CRKL is involved to a greater extent than CRK II in normal signaling pathways that involve c-ABL, C3G and SOS. In BCR/ABL-transformed cells, CRKL but not CRK II, appears to form complexes which potentially link BCR/ABL, c-ABL, C3G, and SOS to the protooncoprotein, p120CBL.  相似文献   
45.
An integrated ultra micro glutamate sensor has been constructed with a 7 μm diameter platinized carbon-fiber disk (PCD) electrode and a platinum thin-film (PTF) counter electrode fabricated on the glass capillary tube. By platinization, the electrode activity of the carbon fiber is improved. In order to obtain a stable response, a pulse potential is applied for hydrogen peroxide measurement. The PTF counter electrode shows good stability and can be used as a substitute for a silver-silver chloride electrode. Since the integrated PCD electrode shows good characteristics as a hydrogen peroxide sensor, glutamate oxidase is immobilized onto the tip of the PCD electrode to construct the ultra micro glutamate sensor. The sensor shows stable response to glutamate and a response time within 12 s. The calibration range for glutamate measurement is 50–800 μM.  相似文献   
46.
OBJECTIVE: Oesophagectomies have a high morbidity rate, mainly related to pulmonary complications. The aim of this work was to assess whether the thoracoscopic approach could reduce this morbidity. PATIENTS AND METHODS: We conducted a prospective study of the results of 26 attempts of esophagectomy using a right thoracoscopic approach. There were 17 males and 9 females having an average age of 47. The indication was a squamous cell carcinoma in 19 patients, an adenocarcinoma in 1 patient, a melanoma in 1 patient and a caustic stenosis in 5. The whole oesophagus was mobilized thoracoscopically, and the eosophagectomy was completed through the abdomen. The reconstruction was achieved using a gastric pull-through and a cervical anastomosis. RESULTS: There were 5 failures for the following reasons: unresectable carcinoma (1 case), large tumour making a thoracoscopic dissection unsafe (1 case) and incomplete lung collapse making the exposure of the posterior mediastinum difficult (2 cases). The average time of the thoracoscopic procedure was 135 min. The post-operative course was uneventful in all but 5 patients who had a pulmonary complication: atelectasis (3 cases), right purulent pleural effusion (1 case), acute respiratory distress syndrome (1 case). The latter complication was lethal. Four out of 5 respiratory complications occurred in patients for whom the dissection was considered as difficult. Among the other complications, there were 5 anastomotic leakages and 3 laryngeal nerve palsy. The mortality rate was 3.8%. CONCLUSION: These initial results do not show a real benefit of the thoracoscopic approach for eosophageal dissection, especially for difficult oesophagectomies. Further evaluation of the technique is needed.  相似文献   
47.
The formation of thin AlN films and some of their electrical properties have been investigated. The films were prepared by exposing the surface of evaporated aluminium films to a glow discharge in pure nitrogen gas. It has been confirmed by transmission electron diffraction that the structure of the film is of the wurtzite type, as is that of the bulk material. It was observed that the thickness of the AlN films depends on the voltage of the glow discharge, the distance from the discharge electrode to the films and the treatment time. The electrical properties were measured in the form of a sandwich diode, i.e. Al-AlN-Au. The voltage-controlled negative resistance, which was first discovered in Al-Al2O3-metal diodes, has also been observed in this nitride film diode and shows very good reproducibility and stability.  相似文献   
48.
The neural activity pattern of the subthalmic nucleus (STN) was investigated in five patients with Parkinson's disease who were scheduled for electrode implantation for chronic stimulation of the STN. The initial target was placed 8 mm or 10 mm lateral to the midline, 3 mm to 4 mm posterior to the midcommissural point, and 5 mm to 6 mm below the intercommissural (AC-PC) line. The STN was identified by semi-microelectrode recordings with a trajectory moving laterally in 2-mm steps. The amplitudes of multi-unit activities were relatively low at depths from 8 mm to 5 mm above and from 1 mm to 4 mm below the target, while those 4 mm to 0 mm above the target were significantly higher than at the other sites (ANOVA, Fisher's test, p < 0.05), with the highest amplitude at 2 mm above the target (91.0 +/- 23.3 mu v, n = 15). In the mediolateral direction, amplitudes were relatively higher in the lateral portion, and amplitudes at 14 mm lateral to the midline were significantly higher than at the other sites (ANOVA, Fisher's test, p < 0.05). The target for chronic electrical stimulation was determined to be at the midpoint of the hyperactive STN, i.e., 12 mm lateral to the midline in three patients and 13 mm lateral in two patients. Movement-related neural activity was observed at 5 sites, i.e., 3 sites responded to passive movement of the contralateral wrist and 2 sites to passive knee and/or ankle movement. In conclusion, our data show that the lateral part of the STN is hyperactive in PD, and recordings of neural activities contributed greatly to identifying the STN and determining the target for chronic stimulation within it.  相似文献   
49.
We describe a surgical technique for replacing the hip joint capsule using synthetic mesh after oncological resections of the proximal femur that resulted in gross intraoperative instability of the prosthetic reconstruction. The results of its use in 13 patients, 6 of whom also had pelvic resections, are described. These patients were selected from a total group of 88 patients undergoing proximal femoral replacement, 75 of whom did not require capsular replacement (none of these 75 patients have experienced dislocation). In the group requiring capsular reconstruction, 1 of 4 patients with bipolar hemiarthroplasty and 4 of 9 patients with total hip replacements experienced dislocation after operation. Of the dislocated total hip replacements, 1 remains chronically dislocated, and 3 were successfully stabilized by open reduction with further capsular augmentation. Given that the resections involved removal of most of the soft tissues stabilizing the hip joint, we believe that the technique of capsular reconstruction is useful in this difficult group of patients.  相似文献   
50.
Vertical-to-surface transmission electrophotonic devices with a vertical-cavity are described. The individually accessed 12×4 arrays are characterized and demonstrated to have uniform room-temperature continuous-wave operating characteristics for a threshold current of ~2.8±0.15 mA and a slope efficiency of ~0.18±0.012 W/A with a single transverse mode. Both low threshold and high efficiency with 5% and 7% deviation, respectively, are achieved simultaneously. These devices can be used to constructing two-dimensional massively parallel optical interconnections  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