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   286篇
  免费   9篇
电工技术   1篇
化学工业   100篇
金属工艺   10篇
机械仪表   8篇
建筑科学   4篇
矿业工程   3篇
能源动力   6篇
轻工业   7篇
水利工程   1篇
石油天然气   13篇
无线电   14篇
一般工业技术   64篇
冶金工业   33篇
原子能技术   7篇
自动化技术   24篇
  2023年   3篇
  2022年   34篇
  2021年   13篇
  2020年   6篇
  2019年   3篇
  2018年   13篇
  2017年   4篇
  2016年   7篇
  2015年   2篇
  2014年   11篇
  2013年   14篇
  2012年   17篇
  2011年   14篇
  2010年   10篇
  2009年   7篇
  2008年   7篇
  2007年   3篇
  2006年   6篇
  2005年   7篇
  2004年   10篇
  2003年   3篇
  2002年   5篇
  2001年   2篇
  2000年   5篇
  1999年   7篇
  1998年   5篇
  1997年   2篇
  1996年   6篇
  1995年   2篇
  1994年   4篇
  1992年   2篇
  1991年   5篇
  1990年   4篇
  1989年   3篇
  1988年   3篇
  1987年   4篇
  1983年   2篇
  1982年   3篇
  1979年   2篇
  1978年   3篇
  1976年   8篇
  1974年   4篇
  1973年   3篇
  1972年   1篇
  1970年   1篇
  1969年   4篇
  1968年   3篇
  1965年   2篇
  1960年   2篇
  1959年   1篇
排序方式: 共有295条查询结果,搜索用时 11 毫秒
31.
With the rapid development of information network, the computing resources and storage capacity of ordinary users cannot meet their needs of data processing. The emergence of cloud computing solves this problem but brings data security problems. How to manage and retrieve ciphertext data effectively becomes a challenging problem. To these problems, a new image retrieval method in ciphertext domain by block image encrypting based on Paillier homomophic cryptosystem is proposed in this paper. This can be described as follows: According to the Paillier encryption technology, the image owner encrypts the original image in blocks, obtains the image in ciphertext domain, then passes it to the third party server. The server calculates the difference histogram of the image in ciphertext domain according to the public key and establishes the index database. The user passes the retrieved image to the server. The server computes the differential histogram of the retrieved image by public key. Then, compares the similarity of it with the histogram in index database and selects larger similarity images in ciphertext and send them to the user. The user obtains the target image with the private key. The experimental results show that the method is feasible and simple.  相似文献   
32.
The duration of a single plasma discharge in the next generation of fusion experiments will be much longer than in the present devices. Storing all raw data acquired in each discharge will be more difficult and the high rates achieved by the new digitizers are already contributing to storage overload. This gap can be mitigated by real time (RT) analysis and compression, using devices such as field programmable gate arrays (FPGAs) capable to transfer and process data on the fly. However, to ensure a correct RT analysis, the FPGA algorithm must be adapted to the signal to be acquired. Since minor changes in signal shape may require significant algorithm modifications, it is important to know in advance the signal attributes. For that reason, the availability of more than one RT algorithm, especially during commissioning of new sub-systems and during campaigns with relevant changes in diagnostic conditions, is advantageous. This paper presents an implementation using two RT algorithms processing simultaneously, developed for the gamma-ray and hard X-ray diagnostics of the Joint European Torus (JET). Both algorithms perform pulse height analysis with pile-up rejection. While the first algorithm is suitable for Gaussian shaped pulses, the second is suitable for exponential signals. The algorithms are selectable by the user, during discharge configuration. Tests with radioactive sources made in JET are presented.  相似文献   
33.
34.
35.
The memory effects in the structure: (Ba Sr) TiO3 film-silicon single crystal have been studied, It is shown that for explaining them it is necessary to take into account both the natural unipolarity of (Ba, Sr) TiO3 film and the injection of carriers from Si. In terms of the results obtained a conclusion has been made on the possibility of using such structures as currentless cells memory for long-term storage of information.  相似文献   
36.
37.
Topographical maps are presented which show lines of constant energy on the three-dimensional nuclear binding energy surfaces which would be obtained by plotting a + bA ? EB as a function of N ? Z and A. Discontinuities in the patterns of these lines occur for Z = 4, 8, 10, 14, 20, 28, 40, 50, 66, 70, and 82 and for N = 4, 8, 10, 14, 20, 22, 28, 50, 82, 88, 114, 126, and 152.  相似文献   
38.
Chemotherapeutic agents exert their antitumor effects by inducing apoptosis. The microculture kinetic (MiCK) assay provides an automated, continuous means of monitoring apoptosis in a cell population. We used the MiCK assay to determine the chemosensitivities of the human promyelocytic HL-60 and lymphoblastic CEM cell lines and leukemia cells freshly isolated from patients with acute nonlymphocytic (ANLL) or acute lymphocytic (ALL) leukemias. Continuous monitoring of apoptosis in the MiCK assay permits determination of the time to the maximum apoptosis (Tm) and its two components which are initiation time (Ti) and development time (Td). Duration of the three timing components of apoptosis varies from hours to days depending on the drug, drug concentration, and type of target cells. In the MiCK assay, the extent of apoptosis is reported in kinetic units of apoptosis. Kinetic units are determined by the slope of the curve created when optical density caused by cell blebbing is plotted as a function of time. Using the leukemia cell lines, we define the relationship between kinetic units determined by the MiCK assay and the percentage of morphologically apoptotic cells in the culture. Flow cytometry analysis of apoptosis in Annexin-V-fluorescein isothiocyanate-labeled preparations of HL-60 and CEM cells was also used to compare with data obtained by the MiCK assay. The feasibility of the MiCK assay of apoptosis as a chemosensitivity test was confirmed by its comparison with a 3H-thymidine incorporation assay. We show that samples from 10 ANLL and ALL patients patients tested for sensitivity to various doses of idarubicin (IDR), daunorubicin (DNR), or mitoxantrone (MTA) gave the same percentages of apoptotic cells when calculated by the MiCK assay as when determined by morphological analysis. The MiCK assay was used for dose-response analyses of the sensitivities to IDR, DNR, and MTA of leukemia cells from 4 other patients (2 ANLL and 2 ALL). The results from both cell lines and patient samples indicate that ANLL cells are more sensitive than ALL cells to all three of these chemotherapeutic agents. However, for individual patients the chemosensitivities varied significantly among the three chemotherapeutic agents. These varying responses to IDR, DNR, and MTA indicate that the MiCK assay results can be of potential use in designing a treatment regimen for a specific patient with acute leukemia. Among several drugs of presumed similar efficacy, the MiCK assay can permit the selection of the specific chemotherapeutic agent that causes the most apoptosis in the patient's leukemic cells.  相似文献   
39.
40.
Heterostructures of strongly correlated oxides demonstrate various intriguing and potentially useful interfacial phenomena. LaMnO3/SrMnO3 superlattices are presented showcasing a new high‐temperature ferromagnetic phase with Curie temperature, TC ≈360 K, caused by electron transfer from the surface of the LaMnO3 donor layer into the neighboring SrMnO3 acceptor layer. As a result, the SrMnO3 (top)/LaMnO3 (bottom) interface shows an enhancement of the magnetization as depth‐profiled by polarized neutron reflectometry. The length scale of charge transfer, λTF ≈2 unit cells, is obtained from in situ growth monitoring by optical ellipsometry, supported by optical simulations, and further confirmed by high resolution electron microscopy and spectroscopy. A model of the inhomogeneous distribution of electron density in LaMnO3/SrMnO3 layers along the growth direction is concluded to account for a complex interplay between ferromagnetic and antiferromagnetic layers in superlattices.  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