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   11122篇
  免费   1373篇
  国内免费   919篇
电工技术   469篇
综合类   726篇
化学工业   687篇
金属工艺   1056篇
机械仪表   438篇
建筑科学   273篇
矿业工程   90篇
能源动力   74篇
轻工业   178篇
水利工程   31篇
石油天然气   112篇
武器工业   85篇
无线电   1778篇
一般工业技术   1526篇
冶金工业   2334篇
原子能技术   59篇
自动化技术   3498篇
  2024年   38篇
  2023年   252篇
  2022年   369篇
  2021年   459篇
  2020年   392篇
  2019年   275篇
  2018年   231篇
  2017年   305篇
  2016年   301篇
  2015年   344篇
  2014年   500篇
  2013年   549篇
  2012年   620篇
  2011年   966篇
  2010年   697篇
  2009年   749篇
  2008年   759篇
  2007年   760篇
  2006年   696篇
  2005年   693篇
  2004年   632篇
  2003年   495篇
  2002年   442篇
  2001年   359篇
  2000年   216篇
  1999年   172篇
  1998年   155篇
  1997年   145篇
  1996年   129篇
  1995年   127篇
  1994年   107篇
  1993年   92篇
  1992年   69篇
  1991年   41篇
  1990年   50篇
  1989年   41篇
  1988年   38篇
  1987年   8篇
  1986年   12篇
  1985年   13篇
  1984年   10篇
  1983年   8篇
  1982年   6篇
  1979年   6篇
  1977年   11篇
  1976年   6篇
  1975年   6篇
  1973年   5篇
  1963年   5篇
  1961年   5篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
11.
12.
In 1937, Sir H. A Krebs first published the Citric Acid Cycle, a unidirectional cycle with carboxylic acids. The original concept of the Citric Acid Cycle from Krebs’ 1953 Nobel Prize lecture illustrates the unidirectional degradation of lactic acid to water, carbon dioxide and hydrogen. Here, we add the heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex, connecting the original Citric Acid Cycle to the flow of energy and material. The heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex catalyses the first reaction of the Citric Acid Cycle, the oxidation of lactate to pyruvate, and thus secures the provision of pyruvic acid. In addition, we modify Krebs’ original concept by feeding the cycle with oxaloacetic acid. Our concept enables the integration of anabolic processes and allows adaption of the organism to recover ATP faster.  相似文献   
13.
Developing wound dressings that have strong adhesion strength without causing any conglutination to the wound site is still challenging. Herein, is proposed that zwitterionic shape memory polymers can be applied as promising candidates for wound dressing. Sulfobetaine methacrylate (SBMA) is copolymerized with 2,3‐dihydroxypropyl methacrylate (DHMA) in the presence of boric acid as a cross‐linking agent. The prepared material exhibits multi‐stimuli responsive shape memory behaviors: it can rapidly return to its initial shape upon heating to 90 °C, and a gradual recovery is also observed by absorbing moisture in humid environments. The shape memory effect can be well adjusted via incorporation of sodium chloride to induce the dissociation of electrostatic interactions between PSBMA chains, leading to reduced transition temperature and faster shape recovery rate. Moreover, the dynamic nature of boron ester bonds and electrostatic interaction endows the material with effective and rapid self‐healing ability. It is also demonstrated that the deployment process of the dressing that a sample with an initially circular shape can perfectly fit and tightly bind to the wound site after moisture‐induced shape recovery. The proposed zwitterionic polymer can possibly extend the application scope of shape memory polymers and pave a new way for the design of wound dressings.  相似文献   
14.
15.
Spark is a distributed data processing framework based on memory. Memory allocation is a focus question of Spark research. A good memory allocation scheme can effectively improve the efficiency of task execution and memory resource utilization of the Spark. Aiming at the memory allocation problem in the Spark2.x version, this paper optimizes the memory allocation strategy by analyzing the Spark memory model, the existing cache replacement algorithms and the memory allocation methods, which is on the basis of minimizing the storage area and allocating the execution area according to the demand. It mainly including two parts: cache replacement optimization and memory allocation optimization. Firstly, in the storage area, the cache replacement algorithm is optimized according to the characteristics of RDD Partition, which is combined with PCA dimension. In this section, the four features of RDD Partition are selected. When the RDD cache is replaced, only two most important features are selected by PCA dimension reduction method each time, thereby ensuring the generalization of the cache replacement strategy. Secondly, the memory allocation strategy of the execution area is optimized according to the memory requirement of Task and the memory space of storage area. In this paper, a series of experiments in Spark on Yarn mode are carried out to verify the effectiveness of the optimization algorithm and improve the cluster performance.  相似文献   
16.
Flash memory bits, like other integrated circuit (IC) devices, are prone to random variability in their actual versus nominal characteristics. We present the use of 1.5-transistor flash memory cells in physically unclonable functions leveraging their erase speed variability. This type of memory is interesting for the internet of things due to its wide availability as intellectual property at foundries. Using experimentally measured results, we show simple methods that provide high reliability with no or limited need for helper data and error correction. High quality fingerprints for IC identification are demonstrated. Moreover, techniques to remove systematic variations from the array response are shown, allowing the resulting binary strings to pass all National Institute of Standards and Technology tests for randomness. Consequently, with low complexity helper functions, true random numbers can be readily produced.  相似文献   
17.
In this paper, a triple shape memory material was prepared by ultra‐simple melt blending from poly(ε‐caprolactone) (PCL), poly(propylene carbonate) (PPC) and ethylene‐α‐octene block copolymer (OBC). The obtained material possessed a co‐continuous phase morphology and presented an excellent triple shape memory effect (triple‐SME). Theoretical prediction demonstrated that a special continuous phase morphology could be constructed by adjusting the proportions of the blend. Moreover, the results indicated that a close relationship existed between the phase morphology and the triple‐SME of PCL/PPC/OBC. The sample with 35 vol% PPC content contributed to the formation of a continuous phase morphology and exhibited the optimal triple‐SME. Additionally, the sample PCL/PPC/OBC (32.5/35/32.5) showed outstanding structure and performance stability during cycle loading–unloading tests, which evidenced the prominent cycling shape memory property (nearly 100% shape fixing and recovery of temporary shape). Overall, this work could provide an efficient, convenient and recyclable method to obtain high‐performance shape memory materials. © 2020 Society of Chemical Industry  相似文献   
18.
1-read/1-write (1R1W) register file (RF) is a popular memory configuration in modern feature rich SoCs requiring significant amount of embedded memory. A memory compiler is constructed using the 8T RF bitcell spanning a range of instances from 32 b to 72 Kb. An 8T low-leakage bitcell of 0.106 μm2 is used in a 14 nm FinFET technology with a 70 nm contacted gate pitch for high-density (HD) two-port (TP) RF memory compiler which achieves 5.66 Mb/mm2 array density for a 72 Kb array which is the highest reported density in 14 nm FinFET technology. The density improvement is achieved by using techniques such as leaf-cell optimization (eliminating transistors), better architectural planning, top level connectivity through leaf-cell abutment and minimizing the number of unique leaf-cells. These techniques are fully compatible with memory compiler usage over the required span. Leakage power is minimized by using power-switches without degrading the density mentioned above. Self-induced supply voltage collapse technique is applied for write and a four stack static keeper is used for read Vmin improvement. Fabricated test chips using 14 nm process have demonstrated 2.33 GHz performance at 1.1 V/25 °C operation. Overall Vmin of 550 mV is achieved with this design at 25 °C. The inbuilt power-switch improves leakage power by 12x in simulation. Approximately 8% die area of a leading 14 nm SoC in commercialization is occupied by these compiled RF instances.  相似文献   
19.
利用风电场历史功率数据预测未来一段时间内的风功率,对保障电网安全稳定运行具有重要的意义。本文提出一种基于奇异谱分析SSA(singular spectrum analysis)和长短时记忆LSTM(long-short term memory net⁃work)网络的时序特征预测框架用于短期风功率的预测。首先通过SSA对历史风功率原始数据进行降噪处理,然后经过数据转换之后,以LSTM网络为基础进行预测模型的训练,最后通过某风电场提供的两个风机的历史功率数据进行验证。实验结果表明,奇异谱分析对风电场的历史数据具有良好的降噪性,SSA+LSTM模型在测试数据上取得了较好的预测性能,能够有效进行短期风功率的预测。  相似文献   
20.
This study investigated the effect of contrast in neutral-, warm-, and cool-colored spaces on spatial memory. Spatial memory was measured in terms of architectural scale and recollection of architectural elements and furniture. Participants (N = 114) viewed a short virtual simulation video of a residential studio and were asked to sketch a map of the architectural elements on distributed grid paper. Spatial memory was measured in terms of scale, and item recall rate. Contrast and hue had no significant effect on the memorization of proportional scale. However, high-contrast schemes allowed for a significantly higher recollection of architectural elements than low-contrast schemes. In comparing the effect of hues, a significant difference was seen in recalling detailed furniture and lighting items. Participants reported significantly better spatial memory of neutral and warm color schemes than of cool color schemes. There was no interaction effect between contrast and hue in the color combinations. These results can be applied in the design of color schemes for architectural spaces requiring enhanced spatial cognition and memory.  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