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   6095篇
  免费   428篇
  国内免费   248篇
电工技术   324篇
综合类   343篇
化学工业   1060篇
金属工艺   376篇
机械仪表   298篇
建筑科学   462篇
矿业工程   124篇
能源动力   222篇
轻工业   387篇
水利工程   84篇
石油天然气   249篇
武器工业   37篇
无线电   665篇
一般工业技术   901篇
冶金工业   419篇
原子能技术   76篇
自动化技术   744篇
  2024年   17篇
  2023年   82篇
  2022年   109篇
  2021年   215篇
  2020年   177篇
  2019年   166篇
  2018年   142篇
  2017年   168篇
  2016年   167篇
  2015年   166篇
  2014年   250篇
  2013年   349篇
  2012年   314篇
  2011年   396篇
  2010年   321篇
  2009年   305篇
  2008年   338篇
  2007年   313篇
  2006年   343篇
  2005年   309篇
  2004年   207篇
  2003年   212篇
  2002年   169篇
  2001年   169篇
  2000年   138篇
  1999年   185篇
  1998年   178篇
  1997年   130篇
  1996年   137篇
  1995年   110篇
  1994年   91篇
  1993年   80篇
  1992年   50篇
  1991年   52篇
  1990年   37篇
  1989年   35篇
  1988年   28篇
  1987年   19篇
  1986年   20篇
  1985年   9篇
  1984年   6篇
  1983年   7篇
  1982年   7篇
  1981年   7篇
  1979年   6篇
  1978年   4篇
  1976年   7篇
  1975年   7篇
  1969年   2篇
  1963年   2篇
排序方式: 共有6771条查询结果,搜索用时 31 毫秒
91.
文章从企业生命周期的角度,探讨了人力资源经理在不同阶段主要扮演的角色,为企业选拔和培训人力资源经理提供新的视角。将企业生命周期分为创业期、成长期、成熟期和衰退期四个阶段,依据企业生命周期不同阶段的特点及人力资源管理的策略,得出人力资源经理在不同阶段分别主要扮演战略合作伙伴、HRM专家、员工激励者、变革推动者的角色。  相似文献   
92.
本文解析如何通过ADO对象对数据库进行操作,并介绍了ADO对象群中的几个重要对象Connection、Recordset、Command等。  相似文献   
93.
魏军从  涂军波 《耐火材料》2006,40(2):100-103
以刚玉、氮化硅、粘土和硅粉为主要原料,在空气气氛下于1550℃保温3h烧成制得刚玉-氮化硅复合材料,研究了硅粉加入量(w)分别为0、4%、8%、12%时对试样常温物理性能、高温抗折强度的影响,并采用XRD、SEM、EDS等手段分析了试样的物相组成和显微结构。结果表明:在硅粉加入量<8%时,Si主要填充在烧成制品基质的空隙中;随着硅粉加入量的增加,制品致密化程度提高,常温强度增大,同时由于硅粉原位生成了纤维状赛隆而使制品的高温强度增大;但在硅粉加入量>8%时,Si可能构成连续相,又导致制品致密度下降和高温力学性能恶化。  相似文献   
94.
For oil sand extractions with microemulsions it is important to disperse large quantities of light hydrocarbons in an aqueous medium. Fundamental studies on the properties of 2-butoxyethanol (BE) and diethylmethylamine (Et2McN) in water suggest that these two liquids could be more effective cosurfactants than the usual alcohols used for this purpose. The phase diagrams of microemulsions using BE and Et2MeN as cosurfactants, combined with typical ionic and non-ionic surfactants and typical aliphatic and aromatic hydrocarbons, were therefore investigated and compared with microemulsions based on n-butanol. Although the phase diagrams depend significantly on the nature of the surfactant and of the oil, the monophasic region generally increases with the cosurfactant in the order n-butanol < Et2McN < BE. With the active mixture BE-cetyltrimethylammonium bromide, temperature has little effect on the phase diagram and NaCl generally destabilizes the microemulsion.  相似文献   
95.
目的 生成式对抗网络(generative adversarial network,GAN)是一种无监督生成模型,通过生成模型和判别模型的博弈学习生成图像。GAN的生成模型是逐级直接生成图像,下级网络无法得知上级网络学习的特征,以至于生成的图像多样性不够丰富。另外,随着网络层数的增加,参数变多,反向传播变得困难,出现训练不稳定和梯度消失等问题。针对上述问题,基于残差网络(residual network,ResNet)和组标准化(group normalization,GN),提出了一种残差生成式对抗网络(residual generative adversarial networks,Re-GAN)。方法 Re-GAN在生成模型中构建深度残差网络模块,通过跳连接的方式融合上级网络学习的特征,增强生成图像的多样性和质量,改善反向传播过程,增强生成式对抗网络的训练稳定性,缓解梯度消失。随后采用组标准化(GN)来适应不同批次的学习,使训练过程更加稳定。结果 在Cifar10、CelebA和LSUN数据集上对算法的性能进行测试。Re-GAN的IS (inception score)均值在批次为64时,比DCGAN (deep convolutional GAN)和WGAN (Wasserstein-GAN)分别提高了5%和30%,在批次为4时,比DCGAN和WGAN分别提高了0.2%和13%,表明无论批次大小,Re-GAN生成图像具有很好的多样性。Re-GAN的FID (Fréchet inception distance)在批次为64时比DCGAN和WGAN分别降低了18%和11%,在批次为4时比DCGAN和WGAN分别降低了4%和10%,表明Re-GAN生成图像的质量更好。同时,Re-GAN缓解了训练过程中出现的训练不稳定和梯度消失等问题。结论 实验结果表明,在图像生成方面,Re-GAN的生成图像质量高、多样性强;在网络训练方面,Re-GAN在不同批次下的训练具有更好的兼容性,使训练过程更加稳定,梯度消失得到缓解。  相似文献   
96.
随着云计算向数据化智能化的方向演进,数据的流转与有效利用将为业务带来核心价值。大规模深度学习、机器训练等应用是极其依赖算力的,大量的信息交互对网络提出了很高的要求,由此需要一个低时延、无丢包、高吞吐的算力网络。考察RDMA[1]技术在数据中心中的应用,并分析其对于未来云数据中心高性能集群计算的影响。  相似文献   
97.
The Cu x Si1-x thin films have been grown by pulsed laser deposition (PLD) with in situ annealing on Si (001) and Si (111), respectively. The transformation of phase was detected by X-ray diffraction (XRD). The results showed that the as-deposited films were composed of Cu on both Si (001) and Si (111). The annealed thin films consisted of Cu + η”-Cu3Si on Si (001) while Cu + η’-Cu3Si on Si (111), respectively, at annealed temperature (T a) = 300-600 °C. With the further increasing of T a, at T a= 700 °C, there was only one main phase, η”-Cu3Si on Si (001) while η’-Cu3Si on Si (111), respectively. The annealed thin films transformed from continuous dense structure to scattered-grain morphology with increasing T a detected by field emission scanning electron microscope (FESEM). It was also showed that the grain size would enlarge with increasing annealing time (t a).  相似文献   
98.
c-axis-oriented SmBa_2Cu_3O_7(SmBCO) films have been deposited on(100)- LaA1O_3(LAO)substrate by metal organic chemical vapor deposition(MOCVD) technique.The effects of deposition temperature(T_(dep)) and total pressure(P_(tot)) on the orientation and microstructure of SmBCO films were investigated.The orientation of SmBCO films transformed from α-axis to c-axis with increasing of T_(dep) from 900 to 1 100℃.At T_(dep)=1 050℃,SmBCO films had c-axis orientation and tetragon surface.At P_(tot)~(dep)=400-800 Pa and T_(dep)=1 050 ℃,totally c-axis-oriented SmBCO films were obtained.The R_(dep) of SmBCO films increased firstly and then decreased with increasing P_(tot).The surface of SmBCO films exhibited tetragon morphology at 1 050 ℃ and400 Pa.Maximum thickness of SmBCO film deposited was 1.2μm at P_(tot)= 600 Pa,and the corresponding R_(dep)was 7.2 μm·h~(-1).  相似文献   
99.
Zhou  Zelin  Chen  Shougen  Tu  Peng  Zhang  Haisheng 《铁道工程科学(英文)》2015,23(4):287-297

Predicting and estimating the response of subway tunnel to adjacent excavation of foundation pit is a research focus in the field of underground engineering. Based on the principle of two-stage method and incremental method, an analytic approach is suggested in this paper to solve this problem in an accurate and rapid way, and the upheavals of tunnel due to adjacent excavation are solved by analytic method. Besides, the presented method is used in the practical engineering case of Shenzhen Metro Line 11 and verified by numerical simulation and in situ measurement. Finally, a parametric analysis is performed to investigate the influence of different factors on tunnel’s deflection. Some useful conclusions have been drawn from the research as below: The deflection results of tunnel obtained from analytic method are nearly consistent with the results getting from numerical analysis and measured data, which verified the accuracy and rationality of presented method. The excavation size has a significant impact on both the displacement values and influenced range of tunnel. However, the relative distance only impacts the displacement values of tunnel, but not the influenced range of tunnel. It may provide certain reference to analyze the deflection of subway tunnel influenced by adjacent excavation.

  相似文献   
100.
Cr2AlC MAX phase thin films prepared by radio-frequency magnetron sputtering were irradiated at room temperature by 100 keV helium ions to a fluence of 1 × 1017 ions cm−2. The effects of thermal annealing on the structural and mechanical properties of the helium-irradiated Cr2AlC films as well as the helium release were investigated by grazing-incidence X-ray diffraction (GIXRD), Raman spectroscopy, and scanning electron microscope (SEM) in combination with nano-indentation and elastic recoil detection (ERD) analysis. The irradiation-induced structural damage in the Cr2AlC is significantly recovered by thermal annealing at temperatures around 600℃, attributed to high defect diffusivity. After annealing to 750℃, the hardness of irradiated films recovered almost completely, which is ascribes to both defect recombination and reformation of damaged chemical bonds. Substantial helium release occurring at this annealing temperature is closely related to the damage recovery due to helium irradiation.  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