全文获取类型
收费全文 | 70615篇 |
免费 | 2109篇 |
国内免费 | 910篇 |
专业分类
电工技术 | 1199篇 |
综合类 | 286篇 |
化学工业 | 11210篇 |
金属工艺 | 3859篇 |
机械仪表 | 2035篇 |
建筑科学 | 1647篇 |
矿业工程 | 296篇 |
能源动力 | 1896篇 |
轻工业 | 6250篇 |
水利工程 | 568篇 |
石油天然气 | 1520篇 |
武器工业 | 10篇 |
无线电 | 5497篇 |
一般工业技术 | 15848篇 |
冶金工业 | 14398篇 |
原子能技术 | 946篇 |
自动化技术 | 6169篇 |
出版年
2023年 | 386篇 |
2022年 | 507篇 |
2021年 | 980篇 |
2020年 | 787篇 |
2019年 | 805篇 |
2018年 | 1550篇 |
2017年 | 1442篇 |
2016年 | 1629篇 |
2015年 | 1315篇 |
2014年 | 1712篇 |
2013年 | 4107篇 |
2012年 | 2734篇 |
2011年 | 3213篇 |
2010年 | 2617篇 |
2009年 | 2836篇 |
2008年 | 2849篇 |
2007年 | 2908篇 |
2006年 | 2218篇 |
2005年 | 1884篇 |
2004年 | 1653篇 |
2003年 | 1529篇 |
2002年 | 1480篇 |
2001年 | 1452篇 |
2000年 | 1280篇 |
1999年 | 1435篇 |
1998年 | 4330篇 |
1997年 | 2989篇 |
1996年 | 2362篇 |
1995年 | 1548篇 |
1994年 | 1214篇 |
1993年 | 1190篇 |
1992年 | 768篇 |
1991年 | 746篇 |
1990年 | 674篇 |
1989年 | 644篇 |
1988年 | 516篇 |
1987年 | 554篇 |
1986年 | 504篇 |
1985年 | 597篇 |
1984年 | 487篇 |
1983年 | 462篇 |
1982年 | 431篇 |
1981年 | 466篇 |
1980年 | 519篇 |
1979年 | 460篇 |
1978年 | 401篇 |
1977年 | 629篇 |
1976年 | 1097篇 |
1975年 | 392篇 |
1973年 | 419篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Iryna Smokovych Manja Krüger Michael Scheffler 《Journal of the European Ceramic Society》2019,39(13):3634-3642
Silica-based coating systems were developed using polymer derived ceramics (PDCs) technology. Ceramic composites on the base of a SiO2 and SiNO matrix and homogeneously distributed Mo5SiB2, SiB6, Si and B fillers were manufactured. The coating systems have low porosity and provide a high oxidation resistance up to 100 h at 800 °C and 1100 °C in air. The influence of temperature and atmosphere of pyrolysis on the polymer precursor, the volume fraction of filler materials on the chemical composition of compacts as well as their high-temperature oxidation protection was investigated. 相似文献
53.
54.
Dr. Li Di Prof. Per Artursson Dr. Alex Avdeef Prof. Leslie Z. Benet Prof. J. Brian Houston Dr. Manfred Kansy Edward H. Kerns Prof. Hans Lennernäs Dr. Dennis A. Smith Prof. Kiyohiko Sugano 《ChemMedChem》2020,15(20):1862-1874
Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients. 相似文献
55.
Based on the phase transformation theories, especially the T0 concept of bainite transformation, alloy optimisation of bainitic steel with carbides has been carried out aiming at the produce of plastic mould with large cross-section. The effect of manganese and silicon on proeutectoid ferrite and bainite transformation is explored by dilatometric analysis, XRD and different microscopy techniques. The results show that after the alloy optimisation, the transformation of proeutectoid ferrite is suppressed and when the cooling rate is lower than 0·1°C?s??1, the new lower bainite transformation appears by decreasing carbon capacity of austenite and promoting carbide precipitation. Industrial production proves that the optimised alloy SDP1 can meet the demand for the plastic mould with the thickness of 1050?mm. 相似文献
56.
57.
58.
Bengü Ergüden 《Yeast (Chichester, England)》2019,36(2):99-105
The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (S my2, E ap1, S cp160, A sc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA. 相似文献
59.
60.
Freddy A. Bernal Dr. Marcel Kaiser Prof. Dr. Bernhard Wünsch Prof. Dr. Thomas J. Schmidt 《ChemMedChem》2020,15(1):68-78
Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model. 相似文献