全文获取类型
收费全文 | 19076篇 |
免费 | 1259篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 346篇 |
综合类 | 54篇 |
化学工业 | 4443篇 |
金属工艺 | 566篇 |
机械仪表 | 476篇 |
建筑科学 | 884篇 |
矿业工程 | 123篇 |
能源动力 | 311篇 |
轻工业 | 2753篇 |
水利工程 | 144篇 |
石油天然气 | 26篇 |
无线电 | 1188篇 |
一般工业技术 | 5180篇 |
冶金工业 | 630篇 |
原子能技术 | 158篇 |
自动化技术 | 3064篇 |
出版年
2023年 | 266篇 |
2022年 | 221篇 |
2021年 | 492篇 |
2020年 | 392篇 |
2019年 | 365篇 |
2018年 | 689篇 |
2017年 | 710篇 |
2016年 | 765篇 |
2015年 | 654篇 |
2014年 | 779篇 |
2013年 | 1556篇 |
2012年 | 970篇 |
2011年 | 1171篇 |
2010年 | 999篇 |
2009年 | 892篇 |
2008年 | 1018篇 |
2007年 | 998篇 |
2006年 | 699篇 |
2005年 | 535篇 |
2004年 | 456篇 |
2003年 | 456篇 |
2002年 | 463篇 |
2001年 | 384篇 |
2000年 | 323篇 |
1999年 | 240篇 |
1998年 | 196篇 |
1997年 | 204篇 |
1996年 | 179篇 |
1995年 | 173篇 |
1994年 | 137篇 |
1993年 | 122篇 |
1992年 | 115篇 |
1991年 | 95篇 |
1990年 | 84篇 |
1989年 | 73篇 |
1988年 | 82篇 |
1987年 | 73篇 |
1985年 | 154篇 |
1984年 | 164篇 |
1983年 | 106篇 |
1982年 | 108篇 |
1981年 | 131篇 |
1980年 | 100篇 |
1979年 | 84篇 |
1978年 | 88篇 |
1977年 | 71篇 |
1976年 | 75篇 |
1975年 | 85篇 |
1974年 | 63篇 |
1973年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Leibetseder Andreas Schoeffmann Klaus Keckstein Jörg Keckstein Simon 《Multimedia Tools and Applications》2022,81(5):6191-6215
Multimedia Tools and Applications - Endometriosis is a common gynecologic condition typically treated via laparoscopic surgery. Its visual versatility makes it hard to identify for non-specialized... 相似文献
3.
4.
Prof. Andrea Baier Dr. Anne Kokel Dr. William Horton Ewa Gizińska Dr. Garima Pandey Prof. Ryszard Szyszka Prof. Béla Török Prof. Marianna Török 《ChemMedChem》2021,16(12):1927-1932
A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH3)2 residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC50 values in the kinase assays. 相似文献
5.
Ida-Marie Andersson Björn Bergenståhl Marcela Alexander Marie Paulsson Maria Glantz 《International Journal of Food Science & Technology》2021,56(1):480-492
During whey powder production, the feed is subjected to several heat treatments which can cause lactosylation of proteins. In this study, lactosylation of whey proteins was evaluated in spray-dried powders before and after storage by varying the native protein fraction as well as the serum protein/lactose ratio in the powders. The lactosylation of native α-lactalbumin and β-lactoglobulin in the powders before storage was not affected to a large extent by the protein denaturation or if the feed had been heat treated in a high or low lactose environment. After storage (relative humidity of 23.5%, 30 °C, 25 days), the kinetic of lactosylation tended to increase with increasing native protein fraction and bulk protein content in the powders. An explanation could be that proteins dissolved in the lactose glassy structure might have a lower reactivity, while proteins present in the protein glassy structure with dissolved lactose may display higher lactosylation reactivity. 相似文献
6.
Reliable prediction of flooding conditions is needed for sizing and operating packed extraction columns. Due to the complex interplay of physicochemical properties, operational parameters and the packing-specific properties, it is challenging to develop accurate semi-empirical or rigorous models with a high validity range. State of the art models may therefore fail to predict flooding accurately. To overcome this problem, a data-driven model based on Gaussian processes is developed to predict flooding for packed liquid-liquid and high-pressure extraction columns. The optimized Gaussian process for the liquid-liquid extraction column results in an average absolute relative error (AARE) of 15.23 %, whereas the algorithm for the high-pressure extraction column results in an AARE of 13.68 %. Both algorithms can predict flooding curves for different packing geometries and chemical systems precisely. 相似文献
7.
Precipitation of calcium deficient hydroxyapatite nanoparticles in an environmentally benign manner by using only dilute solutions of calcium hydroxide and phosphoric acid without pH adjustment and addition of other chemicals, and water, being the only by-product was investigated by using continuous flow Vortex Reactor (VR) and Semi-Batch Reactor (SBR). The effect of hydrodynamics by changing the Reynolds number of the jets providing residence times of 8.4 ms to 4.37 s for VR, and by changing the stirrer speed between 100 rpm (Re = 2656) and 1000 rpm (Re = 26560) for SBR, on the particle size, particle size distribution, and morphology of the particles was investigated for both systems. It has been shown that it is possible to produce pure phase hydroxyapatite nanoparticles in the desired morphology by changing production system, without resorting to additives. While VR produced rod-like particles with the crystallite size around 4 nm, SBR produced spherical particles with the crystallite size of around 5 nm. 相似文献
8.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its... 相似文献
9.
Jennie O'Loughlin Silvia Napolitano Fahad Alkhathami Cillian O'Beirne Daniel Marhöfer Megan O'Shaughnessy Prof. Orla Howe Prof. Matthias Tacke Dr. Marina Rubini 《Chembiochem : a European journal of chemical biology》2021,22(6):1093-1098
Antibiotic resistance is a growing problem for public health and associated with increasing economic costs and mortality rates. Silver and silver-related compounds have been used for centuries due to their antimicrobial properties. In this work, we show that 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene silver(I) acetate/NHC*-Ag-OAc (SBC3) is a reversible, high affinity inhibitor of E. coli thioredoxin reductase (TrxR; Ki=10.8±1.2 nM). Minimal inhibition concentration (MIC) tests with different E. coli and P. aeruginosa strains demonstrated that SBC3 can efficiently inhibit bacterial cell growth, especially in combination with established antibiotics like gentamicin. Our results show that SBC3 is a promising antibiotic drug candidate targeting bacterial TrxR. 相似文献
10.
Fischer-Tropsch synthesis of the CO2 in biogas aims at producing light hydrocarbons and increasing its calorific value for feeding into the grid. Fe catalysts with Mn and K as promoters are supposed to yield high amounts of light hydrocarbons. Using a Fe-Mn-K/MgO catalyst, a parameter screening and long-term experiments were carried out. The catalyst shows, within the examined range, the highest selectivity to C2–C4 hydrocarbons at 450 °C, 8 bar(a), and a gas hourly space velocity of 350 h−1. Calcination of the catalyst resulted in a significant drop of activity and an almost complete loss of selectivity to hydrocarbons. Admixture of steam to the reactant gas lowers the tendency to carbon deposition but also promotes the water-gas shift reaction and results in lower yields of hydrocarbons. 相似文献