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   31003篇
  免费   2866篇
  国内免费   1567篇
电工技术   1722篇
技术理论   1篇
综合类   2301篇
化学工业   5433篇
金属工艺   1890篇
机械仪表   2074篇
建筑科学   2368篇
矿业工程   1003篇
能源动力   826篇
轻工业   2328篇
水利工程   623篇
石油天然气   1681篇
武器工业   241篇
无线电   3530篇
一般工业技术   3480篇
冶金工业   1240篇
原子能技术   399篇
自动化技术   4296篇
  2024年   99篇
  2023年   483篇
  2022年   1026篇
  2021年   1452篇
  2020年   1127篇
  2019年   948篇
  2018年   968篇
  2017年   1020篇
  2016年   995篇
  2015年   1413篇
  2014年   1788篇
  2013年   2045篇
  2012年   2265篇
  2011年   2430篇
  2010年   2092篇
  2009年   2014篇
  2008年   1914篇
  2007年   1722篇
  2006年   1575篇
  2005年   1163篇
  2004年   909篇
  2003年   874篇
  2002年   1053篇
  2001年   889篇
  2000年   625篇
  1999年   611篇
  1998年   401篇
  1997年   310篇
  1996年   293篇
  1995年   257篇
  1994年   188篇
  1993年   142篇
  1992年   70篇
  1991年   59篇
  1990年   54篇
  1989年   49篇
  1988年   34篇
  1987年   21篇
  1986年   13篇
  1985年   10篇
  1984年   5篇
  1983年   5篇
  1982年   5篇
  1981年   4篇
  1980年   4篇
  1979年   7篇
  1959年   2篇
  1951年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Huang  Hui  Jia  Rong  Shi  Xiaoyu  Liang  Jun  Dang  Jian 《Applied Intelligence》2021,51(10):6752-6770
Applied Intelligence - Accurate wind power forecasting plays an increasingly significant role in power grid normal operation with large-scale wind energy. The precise and stable forecasting of wind...  相似文献   
992.
The effects of different isomalt concentrations on the quality of wheat flour dough and spicy wheat gluten sticks (SWGS) were evaluated at the physical, structural and molecular levels. The results showed that the radial expansion rate (RER) and oil absorption rate (OAR) of SWGS increased first and then decreased with increased isomalt supplementation, which reached the maximum at 3 wt%. The pasting properties of wheat starch also changed, and the peak viscosity, breakdown and setback were decreased with the addition of isomalt. Dynamic rheological properties results showed that the storage modulus (G') and loss modulus (G'') increased with the addition of isomalt, which may be attributed to the reinforcement of gluten network structure by hydrogen bonding of isomalt. Scanning electron microscopy (SEM) images illustrated that the SWGS surface becomes smooth and the broken gluten structure was reduced after the addition of different isomalt levels compared with the control group. Overall, the wheat flour dough quality analysis showed that the addition of isomalt could generate a close binding with wheat starch and protein and further strengthen the internal structure of gluten through isomalt hydrogen bonds.  相似文献   
993.
To predict the nonlinear stress-strain behavior and the rupture strength of orthotropic ceramic matrix composites (CMCs) under macroscopic plane stress, a concise damage-based mechanical theory including a new constitutive model and two kinds of failure criteria was developed in the framework of continuum damage mechanics (CDM). The damage constitutive model was established using strain partitioning and damage decoupling methods. Meanwhile, the failure criteria were formulated in terms of damage energy release rate (DERR) in order to correlate the failure property of CMCs with damage driving forces, and the maximum DERR criterion and the interactive DERR criterion were suggested simultaneously. For the sake of model evaluation, the theory was applied to a typical CMC with damageable and nonlinear behavior, that is, 2D-C/SiC. The damage evolution law, strain response and rupture strength under incremental cyclic tension along both on-axis and off-axis directions were completely investigated. Comparison between theoretical predictions and experimental data illustrates that the newly developed mechanical theory is potential to give reasonable and accurate results of both stress-strain response and failure property for orthotropic CMCs.  相似文献   
994.
In order to ameliorate the gel quality of Dosidicus gigas surimi, the effects of laver powder on gel properties, rheological properties, and water-holding capacity (WHC) were investigated. Results indicated that the addition of laver powder could significantly increase the hardness, chewiness, and breaking force of surimi gels. However, the texture indexes and gel strength began to decline when additional amount exceeded 0.6%. Rheological results demonstrated that the addition of laver powder increased the storage modulus (G′) and viscosity of surimi, prolonged protein denaturation temperature in surimi gels. Moreover, the WHC of surimi gel was improved with the increase of laver powder. Further analyses in low-field nuclear magnetic resonance revealed that laver powder could shorten the transverse relaxation time, enhanced the combination with water, and altered the distribution of different water categories. The proportion of bound water and immobilized water reached its maximum and minimum at 0.6% of laver powder, respectively. Correlation analyses showed that WHC of surimi gel was negatively correlated well with the proportion of loose-bound water, but positively correlated with the strong-bound water and free water. In conclusion, the results supported that 0.6% was the optimal additional amount of laver powder for the squid-based surimi production based on the current ingredients of surimi products.  相似文献   
995.
996.
In this paper, we propose a novel formulation extending convolutional neural networks (CNN) to arbitrary two-dimensional manifolds using orthogonal basis functions called Zernike polynomials. In many areas, geometric features play a key role in understanding scientific trends and phenomena, where accurate numerical quantification of geometric features is critical. Recently, CNNs have demonstrated a substantial improvement in extracting and codifying geometric features. However, the progress is mostly centred around computer vision and its applications where an inherent grid-like data representation is naturally present. In contrast, many geometry processing problems deal with curved surfaces and the application of CNNs is not trivial due to the lack of canonical grid-like representation, the absence of globally consistent orientation and the incompatible local discretizations. In this paper, we show that the Zernike polynomials allow rigourous yet practical mathematical generalization of CNNs to arbitrary surfaces. We prove that the convolution of two functions can be represented as a simple dot product between Zernike coefficients and the rotation of a convolution kernel is essentially a set of 2 × 2 rotation matrices applied to the coefficients. The key contribution of this work is in such a computationally efficient but rigorous generalization of the major CNN building blocks.  相似文献   
997.
In this paper, two new analytical attractive (alpha) functions and their derivatives in bulk and nanoconfined pores are developed based on the virial equation of state (EOS) and statistical thermodynamics and are evaluated at different conditions for the first time. A cubic EOS is modified to nanometer scale and applied to predict the thermodynamic and phase properties in bulk and nanoconfined pores coupled with the new analytical alpha functions. The nanoscale-extended EOS coupled with the analytical alpha functions are validated to be accurate by means of the experimental data for the thermodynamic and phase calculations. The alpha functions and dimensionless attractive term A for the O2, Ar, CO2, N2, and C1-C10 are always positive and monotonically decrease with the temperature increases at T ≤ 2000 K in the bulk phase, whereas the second virial coefficients (B2) are always negative and increase with the temperature increases. Moreover, the alpha functions, A, and B2 for all of components remain constant with the decreasing pore radius until rp = 50 nm, the former two of which decrease while the latter one increases by further reducing the pore radius. It should be noted that the intermolecular attractive force (ie, A) is a function of the pressure, which is gradually increased at P ≤ 10 MPa though drastically increases afterwards. Also, the enhanced confinement effects lead the same-component intermolecular attractive forces to be smaller. The analytical formulations in the SRK type slightly outperform in the gaseous or light component cases, while those in the PR type are better for the heavy component cases in terms of the thermodynamic property calculations, both of which are compatible with the modified EOS and analytical alpha functions.  相似文献   
998.
温佳 《山西电子技术》2015,(1):74-75,82
主要内容是基于C++BUILDER的全自动综合验光仪上位机界面设计。该设计严格按照验光标准,结合全自动验光仪特点,设计了良好的人机交互式控制界面,使得操作者可轻松明了地操作该软件从而达到精准地验光效果。  相似文献   
999.
The wear behavior of tire tread rubber composites has attracted widespread attention of researcher duo to its serious environmental pollution and high frequency of occurrence for a long time. Herein, a new test method is developed, an improved Akron friction testing machine on a laboratory scale was utilized to estimate the wear loss and mechanism of the rubber composites under rolling and sliding coupling condition. The results indicated that the wear loss quickly increases with the increase of the relative sliding velocity. The main wear mechanism, including adhesive, thermofatigue, tear and curl wear, was governed by the thermal deposition of the worn surface. Scanning electron microscope analysis showed thermal decomposition tear region gradually expanded on the worn surface by increasing relative sliding velocity. The heat distribution numerical analysis supported the experimental results, which confirmed that the heat distribution of the worn surface is entirely consistent with the distribution of the thermal decomposition tear region.  相似文献   
1000.
Microbiome modulators such as probiotics are known to modulate oral diseases. Very few probiotics are commercially available for use in the oral cavity. In this context, we selected human-origin Lactobacillus salivarius AR809 as a promising oropharyngeal probiotic and characterized its functional and immunomodulatory properties. Results demonstrated that AR809 could efficiently adhere to pharyngeal epithelial FaDu cells, antagonize Staphylococcus aureus, adapt to the oral environment, and modulate host innate immunity by inducing potentially protective effects. Particularly, AR809 diminished proinflammatory activity by enhancing the production of IL10 and inhibiting the expression of tumor necrosis factor-α, IL1B, inducible nitric oxide synthase, and RELA. Finally, we observed that AR809 grew efficiently when cultured in milk, suggesting that the preparation of a fermented milk product containing AR809 could be a practical way to administer this probiotic to humans. In conclusion, AR809 has high potential to adhere to the pharyngeal mucosa and could be applied in novel milk-based probiotic fermented food products.  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