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   5758篇
  免费   357篇
  国内免费   46篇
电工技术   74篇
综合类   20篇
化学工业   1632篇
金属工艺   124篇
机械仪表   220篇
建筑科学   154篇
矿业工程   4篇
能源动力   375篇
轻工业   557篇
水利工程   84篇
石油天然气   36篇
无线电   551篇
一般工业技术   1063篇
冶金工业   276篇
原子能技术   83篇
自动化技术   908篇
  2024年   23篇
  2023年   113篇
  2022年   324篇
  2021年   398篇
  2020年   299篇
  2019年   327篇
  2018年   359篇
  2017年   296篇
  2016年   324篇
  2015年   194篇
  2014年   323篇
  2013年   532篇
  2012年   305篇
  2011年   312篇
  2010年   277篇
  2009年   244篇
  2008年   166篇
  2007年   145篇
  2006年   132篇
  2005年   95篇
  2004年   73篇
  2003年   71篇
  2002年   55篇
  2001年   42篇
  2000年   36篇
  1999年   37篇
  1998年   69篇
  1997年   59篇
  1996年   42篇
  1995年   53篇
  1994年   24篇
  1993年   34篇
  1992年   30篇
  1991年   25篇
  1990年   24篇
  1989年   22篇
  1988年   15篇
  1987年   30篇
  1986年   30篇
  1985年   22篇
  1984年   30篇
  1983年   26篇
  1982年   16篇
  1981年   8篇
  1980年   14篇
  1979年   13篇
  1978年   12篇
  1977年   11篇
  1976年   14篇
  1975年   8篇
排序方式: 共有6161条查询结果,搜索用时 31 毫秒
991.
In the present work, novel modality for lung cancer intervention has been explored. Primary literature has established the potential role of cyclooxygenase-2 (COX-2) inhibitor in regression of multiple forms of carcinomas. To overcome its poor water solubility and boost anticancer activity, etoricoxib (ETO) was chosen as a therapeutic candidate for repurposing and formulated into a nanoemulsion (NE). The prepared ETO loaded NE was characterized for the surface charge, droplet size, surface morphology, and in vitro release. The optimized ETO loaded NE was then investigated for its anticancer potential employing A549 lung cancer cell line via cytotoxicity, apoptotic activity, mitochondrial membrane potential activity, cell migration assay, cell cycle analysis, Caspase-3, 9, and p53 activity by ELISA and molecular biomarker analysis through RT-PCR test. The developed ETO-NE formulation showed adequate homogeneity in the droplet size distribution with polydispersity index (PDI) of (0.2 ± 0.03) and had the lowest possible droplet size (124 ± 2.91 nm) and optimal negative surface charge (−8.19 ± 1.51 mV) indicative of colloidal stability. The MTT assay results demonstrated that ETO-NE exhibited substantial anticancer activity compared to the free drug. The ETO-NE showed a substantially potent cytotoxic effect against lung cancer cells, as was evident from the commencement of apoptosis/necrotic cell death and S-phase cell cycle arrests in A549 cells. The study on these molecules through RT-PCR confirmed that ETO-NE is significantly efficacious in mitigating the abundance of IL-B, IL-6, TNF, COX-2, and NF-kB as compared to the free ETO and control group. The current study demonstrates that ETO-NE represents a feasible approach that could provide clinical benefits for lung cancer patients in the future.  相似文献   
992.
The pyramid architecture is a powerful topology in the area of computer vision. On the other hand, the 3D mesh architecture possesses rich topological features which make it suitable for building scalable parallel processor systems. The usefulness of these two architectures has led us to consider the problem of embedding pyramids into 3D meshes, for which we present two solutions. The first solution, termednatural embedding,maps a pyramid into a 3D mesh such that each level of the pyramid is mapped to a single level of the 3D mesh. The second solution, termedmultiple embedding,allows simultaneous embedding of multiple pyramids into a single 3D mesh. The quality of both solutions is evaluated using dilation and expansion measures. Using the multiple embedding, we are able to obtain an average dilation of 1.26 and a near-optimal expansion of 1.12.  相似文献   
993.
Recently, renewable energy resources and their impacts have sparked a heated debate to resolve the Australian energy crisis. There are many projects launched throughout the country to improve network security and reliability. This paper aims to review the current status of different renewable energy resources along with their impacts on society and the environment. Besides, it provides for the first time the statistics of the documents published in the field of renewable energy in Australia. The statistics include information such as the rate of papers published, possible journals for finding relative paper, types of documents published, top authors, and the most prevalent keywords in the field of renewable energy in Australia. It will focus on solar, wind, biomass, geothermal and hydropower technologies and will investigate the social and environmental impacts of these technologies.  相似文献   
994.
Experiments were conducted to see the effect of irradiation on the thermoluminescence emission from dust of plant nuts such as almond, peanut, pinenut and walnut. Inorganic dust particulate minerals adhering to the nut's surface were collected from unirradiated and irradiated (0.5, 1.0 and 1.5 kGy) samples, and analysed for their thermoluminescence (TL) intensities in the temperature range of 80–320°C at a temperature rate of 10°C/s. It was observed that peaks of the TL signals appeared at 200°C in each case and generally the magnitude of the peak signals of irradiated samples was manifold that of unirradiated controls. Regression and correlation analysis of the data indicated strong relationship between radiation adsorbed dose and TL values at each temperature (r ⪈ 0.96). It was concluded that TL measurements could serve as a fast and reliable method for identifying as well as determining absorbed dose in irradiated plant nuts.  相似文献   
995.
COVID-19 pandemic and associated supply-chain disruptions emphasise the requirement for antimicrobial materials for on-demand manufacturing. Besides aerosol transmission, SARS-CoV-2 is also propagated through contact with virus-contaminated surfaces. As such, the development of effective biofunctional materials that can inactivate SARS-CoV-2 is critical for pandemic preparedness. Such materials will enable the rational development of antiviral devices with prolonged serviceability, reducing the environmental burden of disposable alternatives. This research reveals the novel use of Laser Powder Bed Fusion (LPBF) to 3D print porous Cobalt-Chromium-Molybdenum (Co-Cr-Mo) superalloy with potent antiviral activity (100% viral inactivation in 30 min). The porous material was rationally conceived using a multi-objective surrogate model featuring track thickness (tt) and pore diameter (ϕd) as responses. The regression analysis found the most significant parameters for Co-Cr-Mo track formation to be the interaction effects of scanning rate (Vs) and laser power (Pl) in the order PlVs>Vs>Pl. Contrastively, the pore diameter was found to be primarily driven by the hatch spacing (Sh). The study is the first to demonstrate the superior antiviral properties of 3D printed Co-Cr-Mo superalloy against an enveloped virus used as biosafe viral model of SARS-CoV-2. The material significantly outperforms the viral inactivation time of other broadly used antiviral metals such as copper and silver, as the material’s viral inactivation time was from 5 h to 30 min. As such, the study goes beyond the current state-of-the-art in antiviral alloys to provide extra protection to combat the SARS-CoV-2 viral spread. The evolving nature of the COVID-19 pandemic brings new and unpredictable challenges where on-demand 3D printing of antiviral materials can achieve rapid solutions while reducing the environmental impact of disposable devices.  相似文献   
996.
Motivated by the drawbacks of solution phase processing, an all-dry resist formation process is presented that utilizes amorphous zinc-imidazolate (aZnMIm) films deposited by atomic/molecular layer deposition (ALD/MLD), patterned with electron beam lithography (EBL), and developed by novel low temperature (120 °C) gas phase etching using 1,1,1,5,5,5-hexafluoroacetylacetone (hfacH) to achieve well-resolved 22 nm lines with a pitch of 30 nm. The effects of electron beam irradiation on the chemical structure and hfacH etch resistance of aZnMIm films are investigated, and it is found that electron irradiation degrades the 2-methylimidazolate ligands and transforms aZnMIm into a more dense material that is resistant to etching by hfacH and has a C:N:Zn ratio effectively identical to that of unmodified aZnMIm. These findings showcase the potential for aZnMIm films to function in a dry resist technology. Sensitivity, contrast, and critical dimensions of the patterns are determined to be 37 mC cm−2, 0.87, and 29 nm, respectively, for aZnMIm deposited on silicon substrates and patterned at 30 keV. This work introduces a new direction for solvent-free resist processing, offering the prospect of scalable, high-resolution patterning techniques for advanced semiconductor fabrication processes.  相似文献   
997.
The texture and microstructure of Kradi cheese, an indigenous fresh unripened cheese of Jammu and Kashmir, India, were studied. There were significant differences (P < 0.05) for hardness, adhesiveness, springiness, cohesiveness, chewiness and resilience between samples from four different market areas. The optimised products made in the laboratory from cultures NCDC‐167 and NCDC‐144 showed significant differences (P < 0.05) in the textural and mechanical properties of tensile strength. The microstructure of the market samples was distinguished by the greater size of the voids present in three‐dimensional casein network. The optimised laboratory product had a more compact and fibrous structure compared to the market samples, which was attributed to its higher protein content.  相似文献   
998.
In the present work, the properties of cellulose extracted from mendong fiber have been investigated. The experiments were conducted by two different methods to extract the cellulose from mendong fiber, which is extracted by alkali and alkali assisted by PEF. The cellulose was analyzed using X-ray diffraction, Fourier Transform Infra Red, Thermogravimetric Analysis, and compared with cellulose of commercial product. The morphology of cellulose after extraction was observed using both optical and Scanning Electron Microscope. The crystalline structure properties of cellulose extracted from mendong fiber assisted by pulsed electric field (PEF) were similar to the commercial cellulose.  相似文献   
999.
The objective of this study was to develop calibration models for prediction of moisture content and textural characteristics (fracture force, hardness, apparent modulus of elasticity and compressive energy) of pistachio kernels roasted in different conditions (temperatures 90, 120 and 150 °C; times 20, 35 and 50 min and air velocities 0.5, 1.5 and 2.5 m/s) using Vis/NIR hyperspectral imaging and multivariate analysis. The effects of different pre-processing methods and spectral treatments such as normalization [multiplicative scatter correction (MSC), standard normal variate transformation (SNV)], smoothing (median filter, Savitzky–Golay and Wavelet) and differentiation (first derivative, D1 and second derivative, D2) on the obtained data were investigated. The prediction models were developed by partial least square regression (PLSR) and artificial neural network (ANN). The results indicated that ANN models have higher potential to predict moisture content and textural characteristics of roasted pistachio kernels comparing to PLSR models. High correlation was observed between reflectance data and fracture force (R2?=?0.957 and RMSEP?=?3.386) using MSC, Savitzky–Golay and D1, compressive energy (R2?=?0.907 and RMSEP?=?15.757) using the combination of MSC, Wavelet and D1, moisture content (R2?=?0.907 and RMSEP?=?0.179) and apparent modulus of elasticity (R2?=?0.921 and RMSEP?=?2.366) employing combination of SNV, Wavelet and D1, respectively. Moreover, Vis–NIR data correlated well with hardness (R2?=?0.876 and RMSEP?=?5.216) using SNV, Wavelet and D2. These results showed the capability of Vis/NIR hyperspectral imaging and the central role of multivariate analysis in developing accurate models for prediction of moisture content and textural properties of roasted pistachio kernels.  相似文献   
1000.
Decision trees are among the best-known decision-making techniques and have been used extensively for both data analysis and predictive modeling. BPM+ is a novel process modeling approach that helps represent business process models in a consistent and structured way to meet different stakeholders’ process representation needs. This paper reports on the outcomes of an ontological analysis of the potential use of decision-tree representations as a new BPM+ perspective for the operational level of abstraction. This new perspective effectively demonstrates how a specialized/operational BPM stakeholder perspective can be used to improve the existing organizational business process model repository.  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