首页 | 官方网站   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   2355篇
  免费   52篇
  国内免费   2篇
工业技术   2409篇
  2023年   12篇
  2022年   6篇
  2021年   48篇
  2020年   16篇
  2019年   28篇
  2018年   32篇
  2017年   33篇
  2016年   38篇
  2015年   26篇
  2014年   55篇
  2013年   99篇
  2012年   73篇
  2011年   140篇
  2010年   84篇
  2009年   109篇
  2008年   125篇
  2007年   87篇
  2006年   73篇
  2005年   75篇
  2004年   53篇
  2003年   76篇
  2002年   73篇
  2001年   51篇
  2000年   60篇
  1999年   65篇
  1998年   193篇
  1997年   118篇
  1996年   72篇
  1995年   69篇
  1994年   54篇
  1993年   59篇
  1992年   21篇
  1991年   30篇
  1990年   17篇
  1989年   20篇
  1988年   19篇
  1987年   13篇
  1986年   16篇
  1985年   23篇
  1984年   16篇
  1983年   11篇
  1982年   16篇
  1981年   12篇
  1980年   13篇
  1979年   11篇
  1978年   8篇
  1977年   9篇
  1976年   21篇
  1975年   8篇
  1973年   7篇
排序方式: 共有2409条查询结果,搜索用时 31 毫秒
61.
Abstract — This paper proposes a new process to manufacture cover glass that overcomes a strength trade‐off between the face and the edge. In the process, alkali barrier films are deposited on glass faces before an ion exchange process in order to control face stress properties without inhibiting the edge strengthening. As a demonstration of the process, alkali‐alumino‐silicate glass sheets with sputter‐deposited SiO2 films were chemically strengthened, and then their stress properties and strengths were investigated. As a result, thicker SiO2 films cause lower face DOL (depth of strengthened layer), and it is observed that the faces have lower DOL than the edges. In strength tests corresponding to major fracture modes of smartphone cover glass, specimens with 80–100 nm films have more balanced face performance and better edge impact strengths than the no‐film specimen.  相似文献   
62.
On March 11, 2011, a massive earthquake (magnitude 9.0) and accompanying tsunami hit the Tohoku region of eastern Japan. Since then, the Fukushima Daiichi Nuclear Power Plants have been facing a crisis due to the loss of all power that resulted from the meltdown accidents. Three buildings housing nuclear reactors were seriously damaged from hydrogen explosions, and, in one building, the nuclear reactions became out of control. It was too dangerous for humans to enter the buildings to inspect the damage because radioactive materials were also being released. In response to this crisis, it was decided that mobile rescue robots would be used to carry out surveillance missions. The mobile rescue robots needed could not be delivered to the Tokyo Electric Power Company (TEPCO) until various technical issues were resolved. Those issues involved hardware reliability, communication functions, and the ability of the robots' electronic components to withstand radiation. Additional sensors and functionality that would enable the robots to respond effectively to the crisis were also needed. Available robots were therefore retrofitted for the disaster reponse missions. First, the radiation tolerance of the electronic componenets was checked by means of gamma ray irradiation tests, which were conducted using the facilities of the Japan Atomic Energy Agency (JAEA). The commercial electronic devices used in the original robot systems operated long enough (more than 100 h at a 10% safety margin) in the assumed environment (100 mGy/h). Next, the usability of wireless communication in the target environment was assessed. Such tests were not possible in the target environment itself, so they were performed at the Hamaoka Daiichi Nuclear Power Plants, which are similar to the target environment. As previously predicted, the test results indicated that robust wireless communication would not be possible in the reactor buildings. It was therefore determined that a wired communication device would need to be installed. After TEPCO's official urgent mission proposal was received, the team mounted additional devices to facilitate the installation of a water gauge in the basement of the reactor buildings to determine flooding levels. While these preparations were taking place, prospective robot operators from TEPCO trained in a laboratory environment. Finally, one of the robots was delivered to the Fukushima Daiichi Nuclear Power Plants on June 20, 2011, where it performed a number of important missions inside the buildings. In this paper, the requirements for the exploration mission in the Fukushima Daiichi Nuclear Power Plants are presented, the implementation is discussed, and the results of the mission are reported.  相似文献   
63.
Stochastic resonance (SR) is known as a phenomenon in which the presence of noise helps a nonlinear system in amplifying a weak (under barrier) signal. In this paper, we investigate how SR behavior can be observed in practical autoassociative neural networks with the Hopfield-type memory under the stochastic dynamics. We focus on SR responses in two systems which consist of three and 156 neurons. These cases are considered as effective double-well and multi-well models. It is demonstrated that the neural network can enhance weak subthreshold signals composed of the stored pattern trains and have higher coherence abilities between stimulus and response.  相似文献   
64.
The aim of the study was to assess the speech discrimination ability of postlingually deaf adults implanted with the Combi 40 cochlear implant and to compare the results with the postoperative data published for other devices. The postoperative open and closed set speech perception performance of 21 consecutive patients was tested using a standardized test battery comprising a number, monosyllable, sentence, consonant and vowel discrimination test as well as a rhyme test in the sound only condition. Mean values achieved for each test 1, 6 and 12 months after "switch on" were evaluated. The results demonstrate that all patients have a substantial benefit from their implant and show a continuous improvement in their speech perception abilities with increased device experience. The mean percentages of correct answers after 12 months were 93.4 for numbers, 44.6 for monosyllables, 78.5 for sentences, 67.6 for the rhyme test, 59.8 for vowel, and 67.3 for consonant discrimination. Preoperatively, the mean discrimination score for monosyllables was 0%. The speech discrimination scores of our patients were similar or higher than described for similar patient groups implanted with other devices. The high stimulation rate of the implant system using the continuous interleaved speech processing strategy as well as a deep atraumatic electrode insertion into the apicalmost regions of the scala tympani may be the reason for good performance.  相似文献   
65.
AIMS AND BACKGROUND: Gliomas of the conus medullaris often show characteristic clinical, radiological, and intraoperative features which differ from gliomas involving other parts of the spinal cord. METHODS: Eight patients with histologically verified gliomas of the conus medullaris were diagnosed and studied. RESULTS: There were five men and three women ranging in age from 21 to 59 years. Predominant initial symptoms were back pain (4 cases) and leg weakness (4 cases). The most common findings on admission were flaccid paraparesis with impaired sensation and bladder dysfunction. Postoperative magnetic resonance (MR) images with more than 95% removal of a tumour were defined as "subtotal removal" (noted in 4 of 8 cases), and less than 95% as "partial removal" (4 of 8 cases). All patients had postoperative radiotherapy. During the follow-up period ranging from 3 to 10 years, there was no tumour recurrence or regrowth on MR images. CONCLUSIONS: The postoperative radiotherapy in gliomas of the conus medullaris where total resection is not possible seems provide a beneficial effect on preventing tumour regrowth.  相似文献   
66.
This study investigated the mechanism of right ventricular failure during bypass of the left side of the heart by precisely assessing right ventricular function with use of a conductance catheter. Bypass of the left side of the heart was established with a centrifugal pump in 10 mongrel dogs weighing 11 to 19 kg. Right ventricular function during left heart bypass was evaluated by two parameters that were both derived from measurement of relative change in right ventricular volume by the conductance catheter technique. One parameter was the right ventricular end-systolic pressure-volume relationship as a load-independent index, and the other was the peak right ventricular pressure-right ventricular stroke volume relationship as a "force-velocity relationship." These parameters were measured in both normal and failing hearts while afterload was increased by bilateral intrapulmonary balloon inflation. Moreover, changes in these relationships were observed by varying assist ratios of left heart bypass from 0% to 100%. Failing heart models were induced by normothermic aortic clamping for 20 minutes. The right ventricular end-systolic pressure-volume relationship in normal hearts did not change, irrespective of the assist ratio of left heart bypass, whereas that in failing hearts decreased from 4.25 +/- 1.41 mm Hg/ml without bypass of the left side of the heart to 3.53 +/- 1.30 mm Hg/ml after 100% assist of left heart bypass (p < 0.05). In the peak right ventricular pressure-right ventricular stroke volume relationship, right ventricular stroke volume was almost constant in normal hearts when afterload was increased regardless of the assist ratio of left heart bypass. Moreover, right ventricular stroke volume was maintained at a higher level during bypass of the left side of the heart compared with that without left heart bypass. However, that slope of the relationship in failing hearts was inversely linear and became significantly steeper after 100% assist of bypass of the left side of the heart compared with that without left heart bypass (-0.131 +/- 0.042 versus -0.051 +/- 0.038, p < 0.005). Therefore ++these two slopes of the relationship intersected at a point that was considered the critical point of afterload during bypass of the left side of the heart. In other words, right ventricular stroke volume was decreased by 100% left heart bypass above the critical point of afterload. In conclusion, this study demonstrates not only that bypass of the left side of the heart results in an increase in right ventricular stroke volume in both normal and failing hearts at the physiologic range of afterload, but also that right ventricular function against higher afterload is impaired by 100% assist of bypass of the left side of the heart in failing hearts.  相似文献   
67.
A case study is presented to illustrate a rare condition described by Cotard as "délire de négation". The central symptom is a nihilistic delusion with denial of one's own existence of oneself and that of the external world. In the present case, the syndrome became manifest as an escalation of a recurrent depressive disorder late in life. After initial resistance to therapy, the syndrome was successfully treated with electroconvulsive therapy. For the first time, we report the regional cerebral blood flow measured by 99mTc-HMPAO-SPECT before and after therapy. Before treatment, significant bitemporal hypoperfusion relative to the cerebellum was found, which was no longer demonstrable on remission.  相似文献   
68.
The deoxidation equilibrium of molten titanium and titanium-aluminum alloys saturated with solid CaO has been measured in the temperature range from 1823 to 2023 K. The equilibrium constant of reaction CaO (s)=Ca (mass pct in Ti,Ti-Al)+O (mass pct in Ti,Ti-Al) and the interaction parameter between calcium and oxygen were determined for Ti, TiAl, and TiAl3. The standard Gibbs energy of reaction for TiAl was obtained as follows: $$\Delta G^\circ = 279,000 - 103TJ/mol$$ The possibilities for the deoxidation of titanium and titanium-aluminum alloys by using calcium-based fluxes are discussed.  相似文献   
69.
70.
The Vertical Block–cyclic Distributed Parallel LU Factorization Method (VBPLU) is effectively processed on a distributed memory parallel computer. VBPLU is based on the two techniques, the block algorithm and the aggregation of communications. Since startup time dominates the data communication and the aggregation reduces communication isssues, the total performance has been much improved. Furthermore this method uses long vectors so that it is also advantageous on vector processors. In this paper, we have constructed a modeling of VBPLU using a simplified LogGP model with analytical formulae, and estimated accurately the computational cost taking into account load distributions caused by data layout and process mapping. Some knowledge for optimization of block algorithm has been obtained. Our estimations have been verified through numerical experiments on three different distributed memory parallel computers.  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-23

京公网安备 11010802026262号