全文获取类型
收费全文 | 2865篇 |
免费 | 115篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 101篇 |
综合类 | 4篇 |
化学工业 | 687篇 |
金属工艺 | 89篇 |
机械仪表 | 102篇 |
建筑科学 | 76篇 |
矿业工程 | 2篇 |
能源动力 | 226篇 |
轻工业 | 302篇 |
水利工程 | 34篇 |
石油天然气 | 31篇 |
无线电 | 300篇 |
一般工业技术 | 513篇 |
冶金工业 | 228篇 |
原子能技术 | 16篇 |
自动化技术 | 284篇 |
出版年
2024年 | 9篇 |
2023年 | 36篇 |
2022年 | 61篇 |
2021年 | 129篇 |
2020年 | 86篇 |
2019年 | 86篇 |
2018年 | 132篇 |
2017年 | 108篇 |
2016年 | 106篇 |
2015年 | 84篇 |
2014年 | 105篇 |
2013年 | 282篇 |
2012年 | 203篇 |
2011年 | 192篇 |
2010年 | 141篇 |
2009年 | 135篇 |
2008年 | 110篇 |
2007年 | 95篇 |
2006年 | 84篇 |
2005年 | 70篇 |
2004年 | 51篇 |
2003年 | 61篇 |
2002年 | 47篇 |
2001年 | 46篇 |
2000年 | 49篇 |
1999年 | 31篇 |
1998年 | 74篇 |
1997年 | 46篇 |
1996年 | 39篇 |
1995年 | 39篇 |
1994年 | 21篇 |
1993年 | 30篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1973年 | 3篇 |
排序方式: 共有2995条查询结果,搜索用时 16 毫秒
81.
Synthesis of a polyaminophosphonate and its evaluation as an antiscalant in desalination plant 下载免费PDF全文
The cationic monomer, N,N‐diallyl‐3‐(diethylphosphonato)propylammonium chloride, was cyclopolymerized in aqueous solutions using t‐butylhydroperoxide (TBHP) or ammonium persulfate (APS) as initiators to afford a cationic polyelectrolyte (CPE) having a (diethylphosphonato)propyl pendent. The CPE on acidic hydrolysis of the diester groups gave pH‐responsive polyzwitterionic acid (PZA) which on treatment with one and two equivalents NaOH gave zwitterionic/anionic polyelectrolyte (ZAPE) and dianionic polyelectrolyte (DAPE), respectively. The solution properties of the CPE, PZA, ZAPE, and DAPE were investigated in detail by viscometric technique. For the purpose of comparison, the solution properties of the polymers were correlated to a structurally similar polyzwitterion (PZ) having monoethylphosphonate and NH+ groups. When performance evaluation was carried out for application in reverse osmosis (RO) plants, DAPE at a concentration of 10 ppm in brackish water feed proved very effective as an inhibitor against calcium sulfate scale. POLYM. ENG. SCI., 54:166–174, 2014. © 2013 Society of Plastics Engineers 相似文献
82.
Libo Zhao Xin Guo Xiawei Meng Rahman Hebibul Yulong Zhao Jianzhu Wang Zhuangde Jiang 《Journal of Mechanical Science and Technology》2013,27(8):2383-2389
Based on strain-resistance effect, an ultra-high pressure sensor has been developed with the range of 0–500 MPa. It is mainly composed of the elastic element and sensitive element. This sensor’s range is determined by the elastic element’s structure and material. In order to endure the ultra-high pressure, the elastic element’s material is selected as spring steel, and its structures are analyzed and simulated. After that, the metal strain gauge as the sensitive element is packaged on the elastic element. Then the sensor is developed after some compensation processes are carried out. In the end, the sensor is calibrated. The results show that the sensor has good performance, such as the accuracy of 0.35%FS, which meets the requirements of aerospace, weapons and other fields. 相似文献
83.
Roxana Family Mehran Solati-Hashjin Shahram Namjoy Nik Ali Nemati 《Protection of Metals and Physical Chemistry of Surfaces》2012,48(6):688-691
In this study hydroxyapatite (HA)/zirconia/alumina composite coatings on titanium metal was carried out using Sol-Gel dip coating and calcination process. Hydroxyapatite-Alumina-Zirconia sol, coated samples in three processes by changing final sol stirring time, aging time, calcination temperature of synthesized powder and prepared coating and rate of coating. Some parts of prepared sol were also synthesized and became powder in all three processes. Scanning electron microscopy was used to estimate the particle size of the surface and for morphological analysis. The functional group and crystallization characteristics of the powders were analyzed using (FTIR) and X-Ray diffraction (XRD). Results show that the morphology of HA-Alumina-Zirconia coatings is more homogenous in the second process with 2 hours final sol stirring time, 20 hours aging time under stirring at 60, 675°C calcination temperature for coating and 850°C for powder and 60mm/min rate of dip coating. 相似文献
84.
Yagmur Esemen Mariam Awan Rabeeia Parwez Arsalan Baig Shahinur Rahman Ilaria Masala Sonia Franchini Dimitrios Giakoumettis 《International journal of molecular sciences》2022,23(5)
Glioblastoma (GBM) is the most common and malignant tumour of the central nervous system. Recent appreciation of the heterogeneity amongst these tumours not only changed the WHO classification approach, but also created the need for developing novel and personalised therapies. This systematic review aims to highlight recent advancements in understanding the molecular pathogenesis of the GBM and discuss related novel treatment targets. A systematic search of the literature in the PubMed library was performed following the PRISMA guidelines for molecular pathogenesis and therapeutic advances. Original and meta-analyses studies from the last ten years were reviewed using pre-determined search terms. The results included articles relevant to GBM development focusing on the aberrancy in cell signaling pathways and intracellular events. Theragnostic targets and vaccination to treat GBM were also explored. The molecular pathophysiology of GBM is complex. Our systematic review suggests targeting therapy at the stemness, p53 mediated pathways and immune modulation. Exciting novel immune therapy involving dendritic cell vaccines, B-cell vaccines and viral vectors may be the future of treating GBM. 相似文献
85.
Priti Tagde Agnieszka Najda Kalpana Nagpal Giriraj T. Kulkarni Muddaser Shah Obaid Ullah Sebastian Balant Md. Habibur Rahman 《International journal of molecular sciences》2022,23(5)
Breast cancer is one of the most common types of cancer among women globally. It is caused by mutations in the estrogen/progesterone receptors and conventional treatment methods are commonly utilized. About 70–80 percent of individuals with the early-stage non-metastatic disease may be cured. Conventional treatment is far less than the optimal ratio, as demonstrated through the high mortality rate of women with this cancer. However, conventional treatment methods like surgery, radiotherapy, and chemotherapy are not as effective as expected and lead to concerns about low bioavailability, low cellular uptake, emerging resistance, and adverse toxicities. A nanomedicine-based approach is a promising alternative for breast cancer treatment. The present era is witnessing rapid advancements in nanomedicine as a platform for investigating novel therapeutic applications and modern intelligent healthcare management strategies. This paper focuses on nanomedicine-based therapeutic interventions that are becoming more widely accepted for improving treatment effectiveness and reducing undesired side effects in breast cancer patients. By evaluating the state-of-the-art tools and taking the challenges involved into consideration, various aspects of the proposed nano-enabled therapeutic approaches have been discussed in this review. 相似文献
86.
Solar radiation data are essential in the design of solar energy conversion devices. In this regard, empirical models were selected to estimate the global solar radiation on horizontal and inclined surfaces. The hourly solar radiation data measured at the study area during the period of 2004-2007, were used to calculate solar radiations using selected models. The selected models were compared on the basis of statistical methods. Based on the results, a new model, H/Ho = 0.19490 + 0.4771(n/N) + 0.02994 exp(n/N) has been developed, based on Kadir Bakirci linear exponential model. This is highly recommended to estimate monthly mean daily global solar irradiation, on a horizontal surface. Further, a model to convert horizontal solar global radiation to that of radiation on a tilted surface is also presented. It is based upon a relatively simple model proposed by Olmo et al. which requires only measurements of horizontal solar radiation. The developed model appears to give excellent results and has the advantage of being relatively simple for applications. The present work will help to improve the state of knowledge of global solar radiation to the point where it has applications in the estimation of global solar radiation, both on horizontal and inclined surfaces. 相似文献
87.
International Journal of Steel Structures - Stiffened plates with high slenderness parameters show large out-of-plane deflections, due to elastic buckling, which may occur before the plates reach... 相似文献
88.
Muhammad Younas Sumathi Sethupathi Leong Loong Kong Abdul Rahman Mohamed 《国际能源研究杂志》2018,42(10):3289-3302
H2 was produced from aluminum/water reaction and reacted with CO2 over Ni and Rh based catalysts to optimize the process conditions for CO2 methanation at moderate temperature. Monometallic catalysts were prepared by incorporating Ni and Rh using nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and rhodium(III) chloride trihydrate (RhCl3·3H2O)as a precursor chemical. The preliminary study of the catalysts revealed higher activity and CH4 selectivity for Rh based catalyst compared to that of Ni based catalyst. Further, Rh based catalyst was investigated using response surface methodology (RSM) involving central composite design. The quadratic model was employed to correlate the effects of variable parameters including methanation temperature, %humidity, and catalyst weight with the %CO2 conversion, %CH4 selectivity, and CH4 production capacity. Analysis of variance revealed that methanation temperature and humidity play an important role in CO2 methanation. Higher response values of CO2 conversion (54.4%), CH4 selectivity (73.5%) and CH4 production capacity (8.4 μmol g?1 min?1) were noted at optimum conditions of 206.7°C of methanation temperature, 12.5% humidity and 100 mg of the catalyst. The results demonstrated the ability of Rh catalyst supported on palm shell activated carbon (PSAC) for CO2 methanation at low temperature and atmospheric pressure. 相似文献
89.
Mohammad Shafiur Rahman Kutaila Al-Farsi Salha Saleh Al-Maskari 《International Journal of Food Properties》2018,21(1):849-856
Variability and sensitivity of a portable electronic nose (32 sensors) was assessed by considering different variables for measurement (i.e., reference, standard, first and second purges, sample draw time, waiting time for the volatiles released in the headspace, and mass of sample or headspace volume of the jar containing sample). In this study, dried date-pits were used a model sample. The highest stability was achieved when both reference and standard (i.e., dried date-pits, no heating treatment) were used before test sample measurement. Higher sample draw time more than 10 s significantly decreased the stability, whereas optimum second purge was observed at 50 s. Optimum time to generate volatile was observed as 24 h. A sample of 100 g increased the signal intensity compared to the 50 g sample for the 60°C and 100°C treated samples, while an opposite trend was observed for the 150°C treated sample. Finally, the responses of volatile components in date-pits heated at different temperatures (60°C, 100°C, and 150°C) were measured using the optimum operating conditions. Principal component analysis explored the relationships between the volatile features and classified date-pits heated at different temperatures. The results showed that an electronic nose was able to classify date-pits based on their volatile components generated by different degrees of heating (93.3% accuracy). 相似文献
90.
Abdul Khalib Zahereel Ishwar Ehtiba Farij Omar Ahmad R. Badlishah Salim Naseer Sabri Rahman Mostafijur Li Mingfu 《Multimedia Tools and Applications》2018,77(21):28799-28816
Multimedia Tools and Applications - Adaptive Media Playout (AMP) controls adapt playout rate to prevent buffer outage and to reduce delay in playout. Most AMP techniques use buffer fullness or its... 相似文献