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   5627篇
  免费   517篇
  国内免费   57篇
电工技术   62篇
综合类   23篇
化学工业   1314篇
金属工艺   88篇
机械仪表   271篇
建筑科学   111篇
矿业工程   8篇
能源动力   353篇
轻工业   729篇
水利工程   65篇
石油天然气   33篇
武器工业   1篇
无线电   734篇
一般工业技术   1276篇
冶金工业   87篇
原子能技术   57篇
自动化技术   989篇
  2024年   31篇
  2023年   203篇
  2022年   503篇
  2021年   764篇
  2020年   474篇
  2019年   533篇
  2018年   480篇
  2017年   408篇
  2016年   410篇
  2015年   248篇
  2014年   309篇
  2013年   422篇
  2012年   237篇
  2011年   300篇
  2010年   177篇
  2009年   145篇
  2008年   96篇
  2007年   95篇
  2006年   40篇
  2005年   32篇
  2004年   43篇
  2003年   29篇
  2002年   23篇
  2001年   14篇
  2000年   10篇
  1999年   15篇
  1998年   23篇
  1997年   12篇
  1996年   15篇
  1995年   20篇
  1994年   9篇
  1993年   11篇
  1992年   8篇
  1991年   7篇
  1990年   2篇
  1989年   5篇
  1988年   4篇
  1987年   5篇
  1986年   4篇
  1985年   6篇
  1984年   5篇
  1983年   3篇
  1982年   4篇
  1981年   5篇
  1980年   1篇
  1979年   4篇
  1978年   2篇
  1977年   3篇
  1975年   1篇
  1961年   1篇
排序方式: 共有6201条查询结果,搜索用时 31 毫秒
991.
In this paper, we propose a novel coverless image steganographic scheme based on a generative model. In our scheme, the secret image is first fed to the generative model database, to generate a meaning-normal and independent image different from the secret image. The generated image is then transmitted to the receiver and fed to the generative model database to generate another image visually the same as the secret image. Thus, we only need to transmit the meaning-normal image which is not related to the secret image, and we can achieve the same effect as the transmission of the secret image. This is the first time to propose the coverless image information steganographic scheme based on generative model, compared with the traditional image steganography. The transmitted image is not embedded with any information of the secret image in this method, therefore, can effectively resist steganalysis tools. Experimental results show that our scheme has high capacity, security and reliability.  相似文献   
992.
We evaluated the effect of sequential dual‐frequency ultrasound (SDFU) pretreatments on rapeseed protein enzymolysis, using alcalase as a model enzyme. Hydrolysed protein concentrations, enzymolysis kinetics and thermodynamic parameters were investigated. The results showed that the hydrolysed rapeseed protein concentration following SDFU pretreatments was higher compared to that of the control for up to 75 min of enzymolysis at various substrate concentrations of 5–25 g L?1; both control and SDFU pretreatment groups showed first‐order reaction kinetics. Compared to the control, the Michaelis–Menten constant (KM) value decreased remarkably by 17.61%, while an increase in the binding frequency between enzyme and substrate (KA) by 10.47% was observed. The thermodynamic parameters, enthalpy, entropy and activation energy were reduced in the SDFU pretreatment group compared to the control by 31.78%, 18.0% and 29.56%, respectively. SDFU pretreatment showed little effect on Gibbs free energy at the various temperatures studied.  相似文献   
993.
Metallurgical and Materials Transactions B - This study provides the thermodynamic properties of the Mg-B binary alloys. Experiments were performed to measure the electromotive force (emf) as a...  相似文献   
994.
995.
996.
Nipah virus is one of the most harmful emerging viruses with deadly effects on both humans and animals. Because of the severe outbreaks, in 2018, the World Health Organization focused on the urgent need for the development of effective solutions against the virus. However, up to date, there is no effective vaccine against the Nipah virus in the market. In the current study, the complete proteome of the Nipah virus (nine proteins) was analyzed for the antigenicity score and the virulence role of each protein, where we came up with fusion glycoprotein (F), glycoprotein (G), protein (V), and protein (W) as the candidates for epitope prediction. Following that, the multitope vaccine was designed based on top-ranking CTL, HTL, and BCL epitopes from the selected proteins. We used suitable linkers, adjuvant, and PADRE peptides to finalize the constructed vaccine, which was analyzed for its physicochemical features, antigenicity, toxicity, allergenicity, and solubility. The designed vaccine passed these assessments through computational analysis and, as a final step, we ran a docking analysis between the designed vaccine and TLR-3 and validated the docked complex through molecular dynamics simulation, which estimated a strong binding and supported the nomination of the designed vaccine as a putative solution for Nipah virus. Here, we describe the computational approach for design and analysis of this vaccine.  相似文献   
997.
Mobile ad-hoc networks (MANETs) and wireless sensor networks (WSNs) have gained remarkable appreciation and technological development over the last few years. Despite ease of deployment, tremendous applications and significant advantages, security has always been a challenging issue due to the nature of environments in which nodes operate. Nodes’ physical capture, malicious or selfish behavior cannot be detected by traditional security schemes. Trust and reputation based approaches have gained global recognition in providing additional means of security for decision making in sensor and ad-hoc networks. This paper provides an extensive literature review of trust and reputation based models both in sensor and ad-hoc networks. Based on the mechanism of trust establishment, we categorize the stateof-the-art into two groups namely node-centric trust models and system-centric trust models. Based on trust evidence, initialization, computation, propagation and weight assignments, we evaluate the efficacy of the existing schemes. Finally, we conclude our discussion with identification of some unresolved issues in pursuit of trust and reputation management.  相似文献   
998.
数字影像传感器市场在过去5年中的增长迅速,不但归功于数字静态相机,更归功于相机模块在移动电话中的应用(称之为"手机相机").这种增长方式将在未来数年中持续,并将主要得益于在移动电话中的应用.图1显示了预计仅由移动电话所带动的相机模块增长曲线.在2004年售出的手机相机已有近2亿部,而到2008年时预计这一数字将达到6亿部.  相似文献   
999.
Although once perceived as inert structures that merely serve for lipid storage, lipid droplets (LDs) have proven to be the dynamic organelles that hold many cellular functions. The LDs’ basic structure of a hydrophobic core consisting of neutral lipids and enclosed in a phospholipid monolayer allows for quick lipid accessibility for intracellular energy and membrane production. Whereas formed at the peripheral and perinuclear endoplasmic reticulum, LDs are degraded either in the cytosol by lipolysis or in the vacuoles/lysosomes by autophagy. Autophagy is a regulated breakdown of dysfunctional, damaged, or surplus cellular components. The selective autophagy of LDs is called lipophagy. Here, we review LDs and their degradation by lipophagy in yeast, which proceeds via the micrometer-scale raft-like lipid domains in the vacuolar membrane. These vacuolar microdomains form during nutrient deprivation and facilitate internalization of LDs via the vacuolar membrane invagination and scission. The resultant intra-vacuolar autophagic bodies with LDs inside are broken down by vacuolar lipases and proteases. This type of lipophagy is called microlipophagy as it resembles microautophagy, the type of autophagy when substrates are sequestered right at the surface of a lytic compartment. Yeast microlipophagy via the raft-like vacuolar microdomains is a great model system to study the role of lipid domains in microautophagic pathways.  相似文献   
1000.
A micrototal analytical method assembling in-channel preconcentration, separation, and electrochemical detection steps has been developed for trace phenolic compounds. A micellar electrokinetic chromatography separation technique was coupled with two preconcentration steps of field-amplified sample stacking (FASS) and field-amplified sample injection (FASI). An amperometric detection method with a cellulose-dsDNA-modified, screen-printed carbon electrode was applied to detect preconcentrated and separated species at the end of the channel. The microchip was composed of three parallel channels: first, two are for the sample preconcentration using FASS and FASI methods, and the third one is for the separation and electrochemical detection. The modification of the electrode surface improved the detection performance by enhancing the signal-to-noise characteristic without surface fouling of the electrode. The method was examined for the analysis of eight phenolic compounds. Experimental parameters affecting the analytical performance of the method were assessed and optimized. The preconcentration factor was increased by about 5200-fold as compared with a simple capillary zone electrophoretic analysis using the same channel. Reproducible response was observed during multiple injections of samples with a RSD of <8.0%. The calibration plots were shown to be linear (with the correlation coefficient between 0.9913 and 0.9982) over the range of 0.4-600 nM. The sensitivity was between 0.17 +/- 0.001 and 0.48 +/- 0.006 nA/nM, with the detection limit of approximately 100 to approximately 150 pM based on S/N = 3. The applicability of the method to the direct analysis of trace phenolic compounds in water samples was successfully demonstrated.  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