全文获取类型
收费全文 | 2089篇 |
免费 | 68篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 20篇 |
综合类 | 3篇 |
化学工业 | 552篇 |
金属工艺 | 34篇 |
机械仪表 | 32篇 |
建筑科学 | 102篇 |
矿业工程 | 62篇 |
能源动力 | 36篇 |
轻工业 | 215篇 |
水利工程 | 54篇 |
石油天然气 | 1篇 |
无线电 | 159篇 |
一般工业技术 | 295篇 |
冶金工业 | 173篇 |
原子能技术 | 16篇 |
自动化技术 | 408篇 |
出版年
2021年 | 20篇 |
2019年 | 15篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 60篇 |
2015年 | 51篇 |
2014年 | 75篇 |
2013年 | 87篇 |
2012年 | 134篇 |
2011年 | 120篇 |
2010年 | 78篇 |
2009年 | 83篇 |
2008年 | 80篇 |
2007年 | 85篇 |
2006年 | 112篇 |
2005年 | 48篇 |
2004年 | 30篇 |
2003年 | 48篇 |
2002年 | 52篇 |
2001年 | 23篇 |
2000年 | 28篇 |
1999年 | 32篇 |
1998年 | 20篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 23篇 |
1994年 | 36篇 |
1993年 | 33篇 |
1992年 | 27篇 |
1991年 | 32篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 27篇 |
1984年 | 35篇 |
1983年 | 23篇 |
1982年 | 32篇 |
1981年 | 36篇 |
1980年 | 22篇 |
1979年 | 27篇 |
1978年 | 25篇 |
1977年 | 23篇 |
1976年 | 29篇 |
1975年 | 30篇 |
1974年 | 29篇 |
1973年 | 20篇 |
1972年 | 20篇 |
1970年 | 19篇 |
排序方式: 共有2162条查询结果,搜索用时 31 毫秒
1.
Jens Mller Anne Busch Christian Berens Helmut Hotzel Andreas Burkovski 《International journal of molecular sciences》2021,22(7)
Corynebacterium silvaticum is a newly identified animal pathogen of forest animals such as roe deer and wild boars. The species is closely related to the emerging human pathogen Corynebacterium ulcerans and the widely distributed animal pathogen Corynebacterium pseudotuberculosis. In this study, Corynebacterium silvaticum strain W25 was characterized with respect to its interaction with human cell lines. Microscopy, measurement of transepithelial electric resistance and cytotoxicity assays revealed detrimental effects of C. silvaticum to different human epithelial cell lines and to an invertebrate animal model, Galleria mellonella larvae, comparable to diphtheria toxin-secreting C. ulcerans. Furthermore, the results obtained may indicate a considerable zoonotic potential of this newly identified species. 相似文献
2.
Carina Heisig Jelka Diedenhoven Christopher Jensen Helmut Gehrke Thomas Turek 《化学工程与技术》2020,43(3):484-492
The conversion of bio-based succinic acid (SA) to the value-added chemicals 1,4-butanediol (BDO), γ-butyrolactone (GBL), and tetrahydrofuran (THF) can replace the corresponding petrochemical production routes to achieve a sustainable process. The reaction network for aqueous-phase catalytic hydrogenation of succinic acid over a supported Re-Pd catalyst was identified and the reaction kinetics was determined. With the developed kinetic model, the composition of the product mixture regarding the desired products (BDO, GBL, THF) can be described as a function of educt concentration, temperature, and pressure. The maximum BDO yield was achieved at high pressure and low temperature, while low pressure and high temperature favored GBL and THF production. 相似文献
3.
Gallic Acid Improves Health‐Associated Biochemical Parameters and Prevents Oxidative Damage of DNA in Type 2 Diabetes Patients: Results of a Placebo‐Controlled Pilot Study 下载免费PDF全文
4.
Novel Positive Allosteric Modulators of µ Opioid Receptor—Insight from In Silico and In Vivo Studies
Damian Bartuzi Ewa Kdzierska Agnieszka A. Kaczor Helmut Schmidhammer Dariusz Matosiuk 《International journal of molecular sciences》2020,21(22)
Opioids are the drugs of choice in severe pain management. Unfortunately, their use involves serious, potentially lethal side effects. Therefore, efforts in opioid drug design turn toward safer and more effective mechanisms, including allosteric modulation. In this study, molecular dynamics simulations in silico and ‘writhing’ tests in vivo were used to characterize potential allosteric mechanism of two previously reported compounds. The results suggest that investigated compounds bind to μ opioid receptor in an allosteric site, augmenting action of morphine at subeffective doses, and exerting antinociceptive effect alone at higher doses. Detailed analysis of in silico calculations suggests that first of the compounds behaves more like allosteric agonist, while the second compound acts mainly as a positive allosteric modulator. 相似文献
5.
6.
7.
In recent years, finite element analyses have increasingly been utilized for slope stability problems. In comparison to limit equilibrium methods, numerical analyses do not require any definition of the failure mechanism a priori and enable the determination of the safety level more accurately. The paper compares the performances of strength reduction finite element analysis (SRFEA) with finite element limit analysis (FELA), whereby the focus is related to non-associated plasticity. Displacement-based finite element analyses using a strength reduction technique suffer from numerical instabilities when using non-associated plasticity, especially when dealing with high friction angles but moderate dilatancy angles. The FELA on the other hand provides rigorous upper and lower bounds of the factor of safety (FoS) but is restricted to associated flow rules. Suggestions to overcome this problem, proposed by Davis (1968), lead to conservative FoSs; therefore, an enhanced procedure has been investigated. When using the modified approach, both the SRFEA and the FELA provide very similar results. Further studies highlight the advantages of using an adaptive mesh refinement to determine FoSs. Additionally, it is shown that the initial stress field does not affect the FoS when using a Mohr-Coulomb failure criterion. 相似文献
8.
9.
Michael Härth Andrea Dörnhöfer Joachim Kaschta Helmut Münstedt Dirk W. Schubert 《应用聚合物科学杂志》2021,138(13):50110
This paper compares the molecular structure and rheological properties of a commercial poly(ethylene terephthalate) (PET) after reactive processing with different concentrations of either pyromellitic dianhydride (PMDA) or a multifunctional epoxide (Joncryl®ADR-4368) as a chain extender. By size exclusion chromatography with triple detection, an increase of molar mass, a broadening of molar mass distribution, and the generation of long-chain branched molecules were found for both chain extenders. While gel-free materials were obtained with PMDA, the processing with Joncryl leads to the formation of gels. The effect of branching, indicated by the Mark–Houwink exponent, is more pronounced for materials with Joncryl compared to PMDA and points to a more compact branching structure of the PET/Joncryl molecules. Rheological measurements in shear and elongation support the analysis from SEC and reveal a complex tree-like branching structure for both chain extenders. In addition, the role of the two modifiers with respect to processing was assessed. 相似文献
10.
Single‐step synthesis of a radically polymerizable 1,1′‐bi‐2‐naphthol derivative for asymmetric catalysis 下载免费PDF全文
A new polymerizable 1,1′‐bi‐2‐naphthol derivative for polymer‐supported catalytic asymmetric synthesis is presented. The synthesis is conducted within a single reaction step, which is a major advantage over other approaches presented in the literature. The ligand‐bearing polymer is prepared through copolymerization with N‐isopropylacrylamide. Preliminary experiments on the utility in catalytic asymmetric alkylation reactions reveal the accessibility and activity of the polymer‐attached catalysts. The stereoselectivity of the reaction is found to be somewhat lower than for reactions performed in the presence of free 1,1′‐bi‐2‐naphthol, and thus requires further optimization. The enantiomeric excess of the reaction products was determined via 1H NMR spectroscopy after chiral derivatization with (R)‐α‐methylbenzyl isocyanate. © 2015 Society of Chemical Industry 相似文献