全文获取类型
收费全文 | 24552篇 |
免费 | 1296篇 |
国内免费 | 537篇 |
专业分类
电工技术 | 1062篇 |
技术理论 | 2篇 |
综合类 | 751篇 |
化学工业 | 3867篇 |
金属工艺 | 934篇 |
机械仪表 | 1016篇 |
建筑科学 | 1206篇 |
矿业工程 | 297篇 |
能源动力 | 563篇 |
轻工业 | 2286篇 |
水利工程 | 325篇 |
石油天然气 | 671篇 |
武器工业 | 98篇 |
无线电 | 2722篇 |
一般工业技术 | 3345篇 |
冶金工业 | 3735篇 |
原子能技术 | 355篇 |
自动化技术 | 3150篇 |
出版年
2024年 | 51篇 |
2023年 | 257篇 |
2022年 | 407篇 |
2021年 | 662篇 |
2020年 | 501篇 |
2019年 | 475篇 |
2018年 | 579篇 |
2017年 | 599篇 |
2016年 | 601篇 |
2015年 | 607篇 |
2014年 | 874篇 |
2013年 | 1242篇 |
2012年 | 1145篇 |
2011年 | 1400篇 |
2010年 | 1097篇 |
2009年 | 1092篇 |
2008年 | 1199篇 |
2007年 | 1187篇 |
2006年 | 1045篇 |
2005年 | 962篇 |
2004年 | 707篇 |
2003年 | 690篇 |
2002年 | 731篇 |
2001年 | 652篇 |
2000年 | 533篇 |
1999年 | 536篇 |
1998年 | 1198篇 |
1997年 | 798篇 |
1996年 | 633篇 |
1995年 | 485篇 |
1994年 | 408篇 |
1993年 | 361篇 |
1992年 | 224篇 |
1991年 | 178篇 |
1990年 | 171篇 |
1989年 | 179篇 |
1988年 | 161篇 |
1987年 | 126篇 |
1986年 | 128篇 |
1985年 | 167篇 |
1984年 | 118篇 |
1983年 | 101篇 |
1982年 | 81篇 |
1981年 | 97篇 |
1980年 | 94篇 |
1979年 | 92篇 |
1977年 | 114篇 |
1976年 | 166篇 |
1975年 | 56篇 |
1973年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Sun Woo Jin Gi Ho Lee Ji Yeon Kim Chae Yeon Kim Young Moo Choo Whajung Cho Eun Hee Han Yong Pil Hwang Yong An Kim Hye Gwang Jeong 《International journal of molecular sciences》2022,23(3)
Skeletal muscle is a heterogeneous tissue composed of a variety of functionally different fiber types. Slow-twitch type I muscle fibers are rich with mitochondria, and mitochondrial biogenesis promotes a shift towards more slow fibers. Leucine, a branched-chain amino acid (BCAA), regulates slow-twitch muscle fiber expression and mitochondrial function. The BCAA content is increased in porcine whole-blood protein hydrolysates (PWBPH) but the effect of PWBPH on muscle fiber type conversion is unknown. Supplementation with PWBPH (250 and 500 mg/kg for 5 weeks) increased time to exhaustion in the forced swimming test and the mass of the quadriceps femoris muscle but decreased the levels of blood markers of exercise-induced fatigue. PWBPH also promoted fast-twitch to slow-twitch muscle fiber conversion, elevated the levels of mitochondrial biogenesis markers (SIRT1, p-AMPK, PGC-1α, NRF1 and TFAM) and increased succinate dehydrogenase and malate dehydrogenase activities in ICR mice. Similarly, PWBPH induced markers of slow-twitch muscle fibers and mitochondrial biogenesis in C2C12 myotubes. Moreover, AMPK and SIRT1 inhibition blocked the PWBPH-induced muscle fiber type conversion in C2C12 myotubes. These results indicate that PWBPH enhances exercise performance by promoting slow-twitch muscle fiber expression and mitochondrial function via the AMPK/SIRT1 signaling pathway. 相似文献
992.
993.
994.
995.
996.
997.
Understanding interactions between functionalized gold nanoparticles (NPs) and lipid bilayers is essential for biomedical applications. Experiments have shown that NPs that are stable in solution can assemble into clusters when adsorbed to a lipid bilayer, suggesting that bilayer-mediated interactions facilitate assembly. In this work, we use coarse-grained molecular dynamics simulations to study bilayer-mediated interactions between NPs adsorbed to single- and multicomponent lipid bilayers. We perform unbiased simulations and umbrella sampling calculations using an implicit solvent force field to determine the thermodynamic contributions to assembly. We show that bilayer-mediated interactions drive the assembly of NPs into linear aggregates on liquid-disordered bilayers, which we attribute to a reduction in bilayer curvature. Similar bilayer-mediated interactions induce the alignment of NP clusters with phase boundaries in phase-separated bilayers. Together, these simulation results provide new physical insight into the balance of forces that dictate the assembly of charged NPs at multicomponent lipid bilayer interfaces. 相似文献
998.
The high strength of boron carbide (B4C) is essential in its engineering applications such as wear-resistance and body armors. Here, by employing density functional theory simulations, we demonstrated that the strength of B4C can be enhanced by doping lithium to boron-rich boron carbide (B13C2) to form r-LiB13C2. The bonding analysis on r-LiB13C2 indicates that the electron counting rule (or Wade's rule) is satisfied in r-LiB13C2 whose formula can be written as r-Li+(B12)2-(CB+C). The shear deformation on r-LiB13C2 indicates that its ideal shear strength is larger than that of B4C because of the existing of Li dopant. The failure process of r-LiB13C2 under ideal shear deformation initiates from breaking the icosahedral-icosahedral B-B bonds. Then these B atoms react with the middle B in the C-B-C chain, resulting in the disintegration of icosahedral clusters and brittle failure. More interesting, the nanotwinned r-LiB13C2 is even stronger than r-LiB13C2 because of the directional nature of covalent bonding at the twin boundaries. This suggests that the nanotwinned r-LiB13C2 has a significant enhanced strength compared to B4C. Our simulation results illustrate the deformation mechanism of Li-doped boron carbide and its nanotwinned microstructure. We proposed to improve the strength of boron carbide by doping Li into B13C2 and increasing its twin densities. 相似文献
999.
Avanish Bharati Prakhyat Hejmady Tom Van der Donck Jin Won Seo Ruth Cardinaels Paula Moldenaers 《应用聚合物科学杂志》2020,137(9):48433
An approach to induce conductivity in immiscible polystyrene/polypropylene (PS/PP) blends is described using a percolated conducting polyaniline/polyamide (PANI/PA) filler combined with a polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride compatibilizer. The approach is based on the ability of the compatibilizer to concomitantly stabilize the cocontinuous morphology and to improve the state of dispersion of the PANI/PA filler. Selective localization of PANI/PA in the PS phase with improved filler dispersion is achieved with the optimal master batch (MB) preparation technique followed by its optimized sequence addition to the blend components. This results in an increase in the dc conductivity by six decades as compared with that of the neat compatibilized blend at an effective 4.8-wt % PANI concentration. An investigation of the effect of functionality and concentration of the filler and the compatibilizer on the filler connectivity in the blend is performed. The prevailing specific interactions are analyzed by Fourier transform infrared spectroscopy and thermogravimetric analysis of the MBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48433. 相似文献
1000.
Yahua Lu Zhenping Qin Naixin Wang Hongxia Guo Quanfu An Yucang Liang 《中国化学工程学报》2020,28(10):2533-2541
The wettability of the membrane surface has shown obvious influent on the separation performance of the membrane. In this work, a hydrophilic PDA-[PDDA/TiO2]+ Cl− membrane was prepared by a one-step codeposition of poly(diallyldimethylammonium chloride) (PDDA) polyelectrolyte solution containing positively charged TiO2@PDDA nanoparticles with the assistance of dopamine (DA). Such positively charged membrane can be transformed into a hydrophobic membrane PDA-[PDDA/TiO2]+ PFO− via the counterion exchange between Cl− and PFO− (perfluorooctanoate). The transformation between hydrophilicity and hydrophobicity is reversible. For both hydrophilic and hydrophobic membranes, the nanofiltration performances were respectively investigated by the aqueous solution and ethanol solution of dyes including methyl blue (MB), Congo red (CR) and Evans blue (EB), and as well metal salt aqueous solution. The consecutive running stability and anti-fouling performance of both hydrophilic and hydrophobic membranes were explored. The results revealed that both membranes showed high nanofiltration performances for retention of dyes in (non)aqueous solution. For the hydrophilic membrane, the rejection of salts in a sequence is MgSO4 > Na2SO4 > MgCl2 > NaCl. Moreover, both of the hydrophilic and hydrophobic membranes showed high stability and antifouling property. 相似文献