全文获取类型
收费全文 | 5941篇 |
免费 | 486篇 |
国内免费 | 238篇 |
专业分类
电工技术 | 447篇 |
综合类 | 379篇 |
化学工业 | 957篇 |
金属工艺 | 311篇 |
机械仪表 | 327篇 |
建筑科学 | 484篇 |
矿业工程 | 281篇 |
能源动力 | 130篇 |
轻工业 | 360篇 |
水利工程 | 143篇 |
石油天然气 | 322篇 |
武器工业 | 20篇 |
无线电 | 703篇 |
一般工业技术 | 738篇 |
冶金工业 | 328篇 |
原子能技术 | 82篇 |
自动化技术 | 653篇 |
出版年
2024年 | 15篇 |
2023年 | 94篇 |
2022年 | 141篇 |
2021年 | 207篇 |
2020年 | 164篇 |
2019年 | 153篇 |
2018年 | 184篇 |
2017年 | 181篇 |
2016年 | 176篇 |
2015年 | 249篇 |
2014年 | 307篇 |
2013年 | 328篇 |
2012年 | 356篇 |
2011年 | 392篇 |
2010年 | 331篇 |
2009年 | 322篇 |
2008年 | 352篇 |
2007年 | 333篇 |
2006年 | 330篇 |
2005年 | 294篇 |
2004年 | 196篇 |
2003年 | 170篇 |
2002年 | 172篇 |
2001年 | 136篇 |
2000年 | 161篇 |
1999年 | 156篇 |
1998年 | 123篇 |
1997年 | 107篇 |
1996年 | 101篇 |
1995年 | 90篇 |
1994年 | 73篇 |
1993年 | 49篇 |
1992年 | 58篇 |
1991年 | 36篇 |
1990年 | 29篇 |
1989年 | 25篇 |
1988年 | 17篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有6665条查询结果,搜索用时 15 毫秒
1.
2.
Nianxiu Duan Junjun Li Sha Song Feng Wang Yiwei Yang Di Nie Caifen Wang Yingjie Sheng Yali Tao Jie Gao Can Xu Yan Wei Yong Gan 《Advanced functional materials》2021,31(46):2100605
Tumor-specific enhanced delivery of chemotherapeutics and modulators to tumor cells and activated pancreatic stellate cells (aPSCs), respectively, represents safer and more effective therapy for pancreatic cancer. Herein, a membrane type 1-matrix metalloproteinase (MT1-MMP)-cleavable spacer is used to assemble low-density cRGDfK onto thermosensitive liposomes loaded with phosphorylated calcipotriol (PCAL) and doxorubicin (DOX), yielding MR-T-PD. The liposome-linked cRGDfK prodrug on MR-T-PD surface is first activated by MT1-MMP, which is selectively expressed on tumor endothelial cells, to release cRGDfK. The free cRGDfK specifically promotes tumor angiogenesis, leading to 3.4-fold higher accumulation and a wider distribution of MR-T-PD in tumors. Furthermore, MR-T-PD rapidly releases PCAL and DOX into the interstitium under heat treatment. The released DOX enters tumor cells to induce apoptosis, whereas the PCAL prodrug is converted to CAL by alkaline phosphatase on the surface of aPSCs; CAL can then enter aPSCs to induce quiescence and promote the antitumor effect of DOX. Finally, by enhancing the exposure of DOX and CAL to tumor cells and aPSCs, respectively, in a tumor-specific manner, MR-T-PD exerts superior efficacy (a 5.9-fold decrease in tumor weight) without causing additional side effects. Overall, this prodrug-based smart liposome system represents a promising paradigm for pancreatic cancer therapy. 相似文献
3.
Cellulose nanocrystals (CNCs) are a kind of sustainable nanoparticle from biomass, which are widely used as reinforcing filler and assembly building block for high-performance composites and function materials including biomaterial, optics, and so forth. Here, their unique advantages in material applications were reviewed based on their rod-like morphology, crystalline structure, dimension-related effects, and multi-level order structure. Then, we focused on the molecular engineering of CNCs, including the structure and physicochemical properties of their surface, along with surface modification methods and steric effects. We further discussed the performance-improvement and functionalization methods based on multi-component complex systems, together with the effects of surface molecular engineering on the performance and functions. Meanwhile, methods of optimizing orientation in uniaxial arrays were discussed along with those of enhancing photoluminescence efficiency via surface chemical modification and substance coordination. In the end, we prospected the design, development, and construction methods of new CNCs materials. 相似文献
4.
提出一种将多壁碳纳米管碘化后制备银/多壁碳纳米管(Ag/MWCNTs)复合材料的方法。通过球磨对碘化多壁碳纳米管进行了功能化,并通过透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、拉曼光谱和热重分析(TG)对其进行了表征。结果表明,经碘化处理后,银纳米粒子(Ag-NPs)能更好地粘附在碳纳米管表面,改善了银纳米粒子与碳纳米管之间的连接。羟基(-OH)基团的伸缩振动明显增强,激活了碳纳米管的表面,增加了碳纳米管表面Ag+形核的数量。在260 ℃以下,Ag/MWCNTs复合材料的质量损失小于MWCNTs的质量损失。最后,制备了银-环氧树脂浆料,发现使用Ag/MWCNTs复合物制备的浆料具有最低的电阻率和最高的热导率。 相似文献
5.
Tae-min Yeo Jung-Wook Cho Ivan Hung Zhehong Gan Sabyasachi Sen 《Journal of the American Ceramic Society》2022,105(10):6140-6148
The structure of mold flux glasses in the system CaO-(Na,Li)2O-SiO2-CaF2 with unusually high modifier contents, stabilized by the addition of ∼4 mol% B2O3, is studied using 7Li, 23Na, 19F, 11B, and 29Si magic-angle-spinning (MAS), and 7Li{19F} and 23Na{19F} rotational echo double-resonance (REDOR) nuclear magnetic resonance (NMR) spectroscopy. When taken together, the spectroscopic results indicate that the structure of these glasses consists primarily of dimeric [Si2O7]−6 units that are linked to the (Ca,Na,Li)-O coordination polyhedra, and are interspersed with chains of corner-shared BO3 units. The F atoms in the structure are exclusively bonded to Ca atoms, forming Ca(O,F)n coordination polyhedra. This structural scenario is shown to be consistent with the crystallization of cuspidine (3CaO·2SiO2·CaF2) from the parent melts on slow supercooling. The progressive addition of Li to a Na-containing base composition results in a corresponding increase in the undercooling required for the nucleation of cuspidine in the melt, which is attributed to the frustrated local structure caused by the mixing of alkali ions. 相似文献
6.
Jun Wang Fushuo Wu Ruoan Zou Yueshu Wu Mengdi Gan Jing Feng Xiaoyu Chong 《Journal of the American Ceramic Society》2021,104(11):5873-5882
In this study, high-entropy rare-earth tantalate ceramics (Y0.2Ce0.2Sm0.2Gd0.2Dy0.2)TaO4 ((5RE0.2)TaO4) have been successfully fabricated. The possibility of formation of (5RE0.2)TaO4 was verified via first-principles calculations. In addition, the phase structure, ferroelastic toughening mechanism, thermophysical, and mechanical properties were systematically investigated. The (5RE0.2)TaO4 ceramics have lower phonon thermal conductivity (1.2–2.6 W·m–1·K–1) in the entire temperature range than that of RETaO4 and YSZ. (5RE0.2)TaO4 has a higher fracture toughness and lower brittleness index than YSZ. The thermal expansion coefficients of (5RE0.2)TaO4 are as high as 10.3 × 10-6 K–1 at 1200°C and Young's modulus is 66–189 GPa, and thus, (5RE0.2)TaO4 possesses great potential for application in thermal barrier coatings (TBCs). 相似文献
7.
The Journal of Supercomputing - Dockless bike-sharing is more and more popular all over the world, which enables passengers to choose destinations more flexibly, so that the transfer radius between... 相似文献
8.
9.
Ke Gan Yanjiao Gai Yali Wang Jie Cui Yuju Lu Xiaoyan Zhang Jingjing Liu Jie Xu Jinlong Yang 《International Journal of Applied Ceramic Technology》2020,17(1):274-284
A direct coagulation casting method for silicon carbide ceramic suspension using dispersant crosslink reaction is reported. Polymer electrolyte (polyethyleneimine, PEI) was used as dispersant to prepare silicon carbide suspension. Common food additives (carboxymethyl cellulose, CMC) were used to coagulate the electrosteric stabilized silicon carbide suspension. There was a well disperse silicon carbide suspension with 0.2 wt% PEI at pH = 5-6. Influence of coagulant on viscosity and zeta potential of the silicon carbide suspension was investigated. It indicates that the high solid loading silicon carbide suspension can be destabilized and coagulated at elevated temperature. It can be attribute to the gradual decrease of electrosteric force due to the crosslink reaction between PEI and CMC. Silicon carbide wet green body with compressive strength of 1.99 MPa could be demolded at 70°C which is higher than that prepared by traditional DCC and dispersant reaction method for nonoxide ceramics. Dense silicon carbide ceramics with relative density above 98.8% and 99.3% had been prepared by liquid phase pressureless and hot pressed sintering, respectively. 相似文献