全文获取类型
收费全文 | 322351篇 |
免费 | 9410篇 |
国内免费 | 4876篇 |
专业分类
电工技术 | 8989篇 |
技术理论 | 1篇 |
综合类 | 7086篇 |
化学工业 | 47058篇 |
金属工艺 | 13327篇 |
机械仪表 | 11980篇 |
建筑科学 | 10964篇 |
矿业工程 | 2503篇 |
能源动力 | 9101篇 |
轻工业 | 27368篇 |
水利工程 | 3647篇 |
石油天然气 | 6011篇 |
武器工业 | 560篇 |
无线电 | 42615篇 |
一般工业技术 | 57330篇 |
冶金工业 | 51495篇 |
原子能技术 | 6032篇 |
自动化技术 | 30570篇 |
出版年
2022年 | 2891篇 |
2021年 | 4206篇 |
2020年 | 3173篇 |
2019年 | 3359篇 |
2018年 | 4818篇 |
2017年 | 5085篇 |
2016年 | 5172篇 |
2015年 | 4690篇 |
2014年 | 7278篇 |
2013年 | 15483篇 |
2012年 | 11011篇 |
2011年 | 13718篇 |
2010年 | 11761篇 |
2009年 | 12672篇 |
2008年 | 13177篇 |
2007年 | 12897篇 |
2006年 | 11862篇 |
2005年 | 10276篇 |
2004年 | 9390篇 |
2003年 | 9355篇 |
2002年 | 9403篇 |
2001年 | 9441篇 |
2000年 | 7958篇 |
1999年 | 7815篇 |
1998年 | 17393篇 |
1997年 | 12164篇 |
1996年 | 9490篇 |
1995年 | 7206篇 |
1994年 | 6333篇 |
1993年 | 6165篇 |
1992年 | 4387篇 |
1991年 | 4216篇 |
1990年 | 4014篇 |
1989年 | 3752篇 |
1988年 | 3658篇 |
1987年 | 3094篇 |
1986年 | 2973篇 |
1985年 | 3256篇 |
1984年 | 2965篇 |
1983年 | 2855篇 |
1982年 | 2653篇 |
1981年 | 2560篇 |
1980年 | 2478篇 |
1979年 | 2315篇 |
1978年 | 2115篇 |
1977年 | 2616篇 |
1976年 | 3576篇 |
1975年 | 1770篇 |
1974年 | 1733篇 |
1973年 | 1667篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Boltar K. O. Burlakov I. D. Iakovleva N. I. Vlasov P. V. Lazarev P. S. 《Journal of Communications Technology and Electronics》2022,67(9):1175-1184
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of... 相似文献
12.
Mobile Networks and Applications - Project MindCatcher is an art/research project which has the intention to explore the potential of interactive artistic environments for measuring and a better... 相似文献
13.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the... 相似文献
14.
Shuang Chen Chao Yu Zhanfang Cao Xiaoping Huang Shuai Wang Hong Zhong 《International Journal of Hydrogen Energy》2021,46(10):7037-7046
The development of efficient and stable oxygen evolution reaction (OER) catalysts is an ongoing challenge. In order to solve the problem of low oxygen evolution efficiency of the current OER catalysts, a novel material was synthesized by the incorporation of NiFeCr-LDH and MoS2, and its structural and electrochemical properties were also investigated. The introduction of MoS2 improves the electrochemical performance of NiFeCr-LDH. The polarization curve shows that the potential of composite material is only 1.50 V at a current density of 10 mA cm?2, which is far superior to commercial precious metal catalysts. In addition, the stability experiment shows that the composite material has excellent stability, and the current density has little change after 500 cycles. Furthermore, we found that some metal ions, such as Ni, Cr and Mo, exist in the form of high valence on the surface of NiFeCr-LDH@MoS2, which is also conducive to the occurrence of oxygen evolution reaction. 相似文献
15.
A. Nakano T. Shimazaki M. Sekiya H. Shiozawa K. Ohtsuka A. Aoyagi T. Iwakiri Z. Mikami M. Sato Y. Sugino K. Kinoshita T. Matsuoka T. Imamura Y. Takayama K. Yamamoto 《International Journal of Hydrogen Energy》2021,46(29):15649-15659
Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa. 相似文献
16.
As G protein coupled receptors, sphingosine-1-phosphate receptors (S1PRs) have recently gained attention for their role in modulating inflammatory bone loss diseases. Notably, in murine studies inhibiting S1PR2 by its specific inhibitor, JTE013, alleviated osteoporosis induced by RANKL and attenuated periodontal alveolar bone loss induced by oral bacterial inflammation. Treatment with a multiple S1PRs modulator, FTY720, also suppressed ovariectomy-induced osteoporosis, collagen or adjuvant-induced arthritis, and apical periodontitis in mice. However, most previous studies and reviews have focused mainly on how S1PRs manipulate S1P signaling pathways, subsequently affecting various diseases. In this review, we summarize the underlying mechanisms associated with JTE013 and FTY720 in modulating inflammatory cytokine release, cell chemotaxis, and osteoclastogenesis, subsequently influencing inflammatory bone loss diseases. Studies from our group and from other labs indicate that S1PRs not only control S1P signaling, they also regulate signaling pathways induced by other stimuli, including bacteria, lipopolysaccharide (LPS), bile acid, receptor activator of nuclear factor κB ligand (RANKL), IL-6, and vitamin D. JTE013 and FTY720 alleviate inflammatory bone loss by decreasing the production of inflammatory cytokines and chemokines, reducing chemotaxis of inflammatory cells from blood circulation to bone and soft tissues, and suppressing RANKL-induced osteoclast formation. 相似文献
17.
Yu-Hung Lee Ching-Fang Yu Ying-Chieh Yang Ji-Hong Hong Chi-Shiun Chiang 《International journal of molecular sciences》2021,22(4)
The low overall survival rate of patients with pancreatic cancer has driven research to seek a new therapeutic protocol. Radiotherapy (RT) is frequently an option in the neoadjuvant or palliative settings for pancreatic cancer treatment. This study explored the effect of RT protocols on the tumor microenvironment (TME) and their consequent impact on anti-programmed cell death ligand-1 (PD-L1) therapy. Using a murine orthotopic pancreatic tumor model, UN-KC-6141, RT-disturbed TME was examined by immunohistochemical staining. The results showed that ablative RT is more effective than fractionated RT at recruiting T cells. On the other hand, fractionated RT induces more myeloid-derived suppressor cell infiltration than ablative RT. The RT-disturbed TME presents a higher perfusion rate per vessel. The increase in vessel perfusion is associated with a higher amount of anti-PD-L1 antibody being delivered to the tumor. Animal survival is increased by anti-PD-L1 therapy after ablative RT, with 67% of treated animals surviving more than 30 days after tumor inoculation compared to a median survival time of 16.5 days for the control group. Splenocytes isolated from surviving animals were specifically cytotoxic for UN-KC-6141 cells. We conclude that the ablative RT-induced TME is more suited than conventional RT-induced TME to combination therapy with immune checkpoint blockade. 相似文献
18.
Zhuchkov V. I. Nazansky S. L. Frolkova A. K. Ganina K. D. 《Theoretical Foundations of Chemical Engineering》2021,55(4):786-791
Theoretical Foundations of Chemical Engineering - Using gas–liquid chromatography, the activity coefficients upon the infinite dilution of the components of the reaction mixture for obtaining... 相似文献
19.
Abhendra K. Singh Kaitlyn Kahle Hannah James Allison L. Horner Daniel Villaflor Zach Benedict 《Ceramics International》2021,47(12):17268-17275
In this study the effects of high temperature and moisture on the impact damage resistance and mechanical strength of Nextel 610/alumina silicate ceramic matrix composites were experimentally evaluated. Composite laminates were exposed to either a 1050°C isothermal furnace-based environment for 30 consecutive days at 6 h a day, or 95% relative humidity environment for 13 consecutive days at 67°C. Low velocity impact, tensile and short beam strength tests were performed on both ambient and environmentally conditioned laminates and damage was characterized using a combination of non-destructive and destructive techniques. High temperature and humidity environmental exposure adversely affected the impact resistance of the composite laminates. For all the environments, planar internal damage area was greater than the back side dent area, which in turn was greater than the impactor side dent area. Evidence of environmental embrittlement through a stiffer tensile response was noted for the high temperature exposed laminates while the short beam strength tests showed greater propensity for interlaminar shear failure in the moisture exposed laminates. Destructive evaluations exposed larger, more pronounced delaminations in the environmentally conditioned laminates in comparison to the ambient ones. External damage metrics of the impactor side dent depth and area directly influenced the post-impact tensile strength of the laminates while no such trend between internal damage area and residual strength could be ascertained. 相似文献
20.
An ecofriendly and biodegradable porous structure was prepared from drying aqueous foams based on nano fibrillated cellulose (NFC), extracted from softwood pulp by subcritical water/CO2 treatment (SC-NFC). The primary aim of this work was to use the modified SC-NFC as stabilizer for a water-based Pickering emulsion which upon drying, yielded porous cellulosic materials, a good dye adsorbent. In order to exploit the carboxymethylated SC-NFC (CMSC-NFC, with a degree of substitution of 0.35 and a charge density of 649 μeqv/g) as a stabilizer for water-based Pickering emulsion in subsequent step, an optimized quantity of octyl amine (30 mg/g of SC-NFC) was added to make them partially hydrophobic. A series of dry foam structures were prepared by varying the concentrations of treated CMSC-NFCs and 4 wt% was found to be the optimum concentration to yield foam with high porosity (99%) and low density (0.038 g/cc) along with high compression strength (0.24 MPa), superior to the conventionally extracted NFC. The foams were applied to capture as high as 98% of methylene blue dyes, making them a potential green candidate for treating industrial effluent. In addition, the dye adsorption kinetics and isotherms were found to be well suited with second order kinetics and Langmuir isotherm models. 相似文献