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   7172篇
  免费   259篇
  国内免费   34篇
电工技术   110篇
综合类   13篇
化学工业   1435篇
金属工艺   200篇
机械仪表   173篇
建筑科学   94篇
矿业工程   19篇
能源动力   405篇
轻工业   350篇
水利工程   41篇
石油天然气   36篇
无线电   988篇
一般工业技术   1635篇
冶金工业   1034篇
原子能技术   53篇
自动化技术   879篇
  2023年   93篇
  2022年   167篇
  2021年   246篇
  2020年   193篇
  2019年   177篇
  2018年   248篇
  2017年   221篇
  2016年   251篇
  2015年   149篇
  2014年   263篇
  2013年   553篇
  2012年   316篇
  2011年   338篇
  2010年   271篇
  2009年   356篇
  2008年   264篇
  2007年   224篇
  2006年   206篇
  2005年   160篇
  2004年   149篇
  2003年   146篇
  2002年   141篇
  2001年   108篇
  2000年   97篇
  1999年   111篇
  1998年   239篇
  1997年   166篇
  1996年   171篇
  1995年   133篇
  1994年   120篇
  1993年   109篇
  1992年   91篇
  1991年   95篇
  1990年   94篇
  1989年   64篇
  1988年   71篇
  1987年   55篇
  1986年   55篇
  1985年   60篇
  1984年   45篇
  1983年   40篇
  1982年   37篇
  1981年   47篇
  1980年   25篇
  1979年   44篇
  1978年   44篇
  1977年   35篇
  1976年   52篇
  1975年   20篇
  1973年   25篇
排序方式: 共有7465条查询结果,搜索用时 15 毫秒
941.
Rice wine was prepared in the laboratory from a black pigmented rice (cv. Poireton) using standardized methodology. The wine was fortified with the probiotic strains Lactobacillus acidophilus ATCC 4356 and Lactobacillus sakei ATCC 15521 and allowed to undergo a storage period of 28 days at 4°C. These rice wines were compared with a commercial wine used as a standard reference wine. A panel consisting of 30 judges performed the sensory evaluation. The scores obtained were based on the quality attributes of colour, taste, aroma and alcoholic strength. Analysis of the sensory scores and ranking of the different samples were performed using fuzzy analysis. The quality attributes were also ranked according to their importance in the overall acceptability. Colour and alcoholic strength were accorded the highest importance, compared with aroma and taste, as quality attributes. The rice wines were rated as ‘not satisfactory’, ‘fair’, ‘medium’, ‘good’ and ‘excellent’ on the sensory scale. Out of the wines prepared, black pigmented rice wine fortified with L. acidophilus was the most acceptable and was ranked as ‘good’, which was also at par with the commercial wine. On the other hand, black pigmented rice wine fortified with L. sakei and black pigmented rice wine fortified with L. acidophilus and L. sakei were ranked in the ‘satisfactory’ category followed by the unfortified wine ranked in the ‘fair’ category. Copyright © 2015 The Institute of Brewing & Distilling  相似文献   
942.
943.
944.
This article presents the two-dimensional mixed convective MHD unsteady stagnation-point flow with heat and mass transfer on chemically reactive Casson fluid towards a vertical stretching surface. This fluid flow model is influenced by the induced magnetic field, thermal radiation, viscous dissipation, heat absorption, and Soret effect with convective boundary conditions and solved numerically by shooting technique. The calculations are accomplished by MATLAB bvp4c. The velocity, induced magnetic field, temperature, and concentration distributions are displayed by graphs for pertinent influential parameters. The numerical results for skin friction coefficient, rate of heat, and mass transfer are analyzed via tables for different influential parameters for both assisting and opposing flows. The results reveal that the enhancement of the unsteadiness parameter diminishes velocity and induced magnetic field but it rises temperature and concentration distributions. Moreover, higher values of magnetic Prandtl number enhance Nusselt number and skin friction coefficient, but it has the opposite impact on Sherwood number. We observe that the amplitude is higher in assisting flow compared to opposing flow for skin friction coefficient and Nusselt number whereas opposite trends are noticed for Sherwood number. Our model will be applicable to various magnetohydrodynamic devices and medical sciences.  相似文献   
945.
The investigation was aimed at assessing anti-inflammatory and antioxidative activities along with the release of peptides with antioxidative properties during the fermentation of camel milk by Lacticaseibacillus casei (NK9). Reverse-phase high-performance liquid chromatography (RP-HPLC) was used to separate the bioactive peptides of 3 and 10 kDa (permeates and retentates). Reverse-phase liquid chromatography–mass spectrometry (RPLC/MS) was used to identify and characterise the pure bioactive peptides, and the effect of fermented camel milk on inflammation produced by lipopolysaccharide (LPS)/endotoxin in RAW 264.7 (Ralph and William's cell line) was also examined. Furthermore, docking revealed that peptides (LLNEK and IYTFPQPQSL) were predicted to inhibit myeloperoxidase (nMPO) activity by engaging with different residues in and around the human myeloperoxidase (hMPO) active site.  相似文献   
946.
In the present work, we have studied the hydrogen absorption–desorption properties of the Ti2CrV alloy, and effect of cycling on the hydrogen storage capacity. The material has been characterized for the structure, morphology, pressure composition isotherms, hydrogen storage capacity, hydrogen absorption kinetics and the desorption profile at different temperatures in detail. The Ti2CrV crystallizes in body centered cubic (bcc) structure like TiCrV. The pressure composition isotherm of the alloy has been measured at room temperature and at 373K. The Ti2CrV alloy shows maximum hydrogen storage capacity of 4.37 wt.% at room temperature. The cyclic hydrogen absorption capacity of Ti2CrV alloy has been investigated at room temperature upto 10th cycle. The hydrogen storage capacity decreased progressively with cycling initially, but the alloy can maintain steady cyclic hydrogen absorption capacity 3.5 wt.% after 5th cycle. To get insight about the desorption behavior of the hydride in-situ desorption has been done at different temperatures and the amount of hydrogen desorbed has been calculated. The TG (Thermo gravimetric) and DTA analysis has been done on uncycled hydride shows that the surface poisoned sample gives a desorption onset temperature of 675K. The DSC measurement of uncycle and multi-cycled saturated hydrides shows that the hydrogen desorption temperature decreasing with cycling.  相似文献   
947.
Soy whey is generated as a process waste while preparing soy based food products tofu, causing environmental pollution and also representing an economic penalty against the industrial process. Therefore, its valorization is of prime importance to the industry. The present investigation aims to convert this proteinaceous waste into bioactive peptide enriched hydrolysate. Soy whey protein was enzymatically treated with the Aspergillus awamori nakazawa protease. Respective protease was efficient to produce antioxidant peptide beholding radical scavenging ability of 40–50% at normal conditions. Remarkable increase in the radical scavenging activity upto 70% was noticed at the response surface methodology (RSM) based optimized condition: temperature 40°C, salt concentration (NaCl) 0.05 M, surfactant concentration (Triton-X 100) 0.0075%, hydrolysis time 80 min, and enzyme to substrate concentration 164 IU/g of soy whey protein. The present study emphasizes the biotransformation of proteineceous waste into antioxidant peptide rich soy whey protein hydrolysate to be considered as additives for food preparation and formulation.  相似文献   
948.
Ultraviolet protection factor (UPF) of fabrics made of 100% cotton and 100% bamboo viscose yarns were studied and a comparative analysis carried out using curve fitting technique. Bamboo viscose fabrics showed higher shrinkage, cover percentage, areal density and UPF compared to its cotton counterpart woven with identical yarn counts and fabric sett. However, the predictive model of cotton fabric UPF using fabric areal density as the input was able to estimate the UPF of bamboo viscose fabrics with very good accuracy. Furthermore, the 100% cotton and 100% bamboo viscose fabrics showed the same UPF if their cover percentage and areal density is similar. It is inferred from the analysis that the apparently higher UPF of bamboo viscose fabrics can be attributed to their higher cover percentage and areal density instead of bamboo’s inherent UV protective property which has been claimed in various literatures.  相似文献   
949.
The effects of ring frame process parameters affecting the packing of yarn, namely yarn twist, spindle speed and draft at ring frame, on fabric transmission characteristic have been reported in the present paper. The detailed results on the yarn characteristics and low-stress mechanical properties, due to change of these ring frame parameters, have been reported in Part I of this series. It has been observed that there is very strong evidence that by changing the above ring frame process parameters, which affect the packing factor of yarn, the transmission characteristics of the fabrics can be manipulated. The yarn packing factor is directly related with the yarn diameter. All the studied ring frame process parameters have direct relationship with air permeability, thermal conductivity and relative water vapour permeability, i.e. with the increase in these ring frame parameters the above fabric transmission parameters increase, but water retention characteristics show opposite trend. Thermal absorptivity was found to be related with the fabric surface roughness.  相似文献   
950.
Rayleigh–Benard (R-B) convection in water-based alumina (Al2O3) nanofluid is analyzed based on a single-component non-homogeneous volume fraction model (SCNHM) using the lattice Boltzmann method (LBM). The present model accounts for the slip mechanisms such as Brownian and thermophoresis between the nanoparticle and the base fluid. The average Nusselt number at the bottom wall for pure water is compared to the previous numerical data for natural convection in a cavity and a good agreement is obtained. The parameters considered in this study include the Rayleigh number of the nanofluid, the volume fraction of alumina nanoparticle and the aspect ratio of the cavity. For the Al2O3/water nanofluid, it is found that heat transfer rate decreases with an increase of the volume fraction of the nanoparticle. The results are demonstrated and explained with average Nusselt number, isotherms, streamlines, heat lines, and nanoparticle distribution. The effect of nanoparticles on the onset of instability in R-B convection is also analyzed.  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