全文获取类型
收费全文 | 2678篇 |
免费 | 85篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 25篇 |
综合类 | 5篇 |
化学工业 | 998篇 |
金属工艺 | 64篇 |
机械仪表 | 45篇 |
建筑科学 | 204篇 |
矿业工程 | 6篇 |
能源动力 | 71篇 |
轻工业 | 214篇 |
水利工程 | 18篇 |
石油天然气 | 2篇 |
武器工业 | 4篇 |
无线电 | 162篇 |
一般工业技术 | 346篇 |
冶金工业 | 218篇 |
原子能技术 | 35篇 |
自动化技术 | 348篇 |
出版年
2022年 | 18篇 |
2021年 | 61篇 |
2020年 | 34篇 |
2019年 | 29篇 |
2018年 | 36篇 |
2017年 | 30篇 |
2016年 | 68篇 |
2015年 | 63篇 |
2014年 | 56篇 |
2013年 | 113篇 |
2012年 | 96篇 |
2011年 | 130篇 |
2010年 | 110篇 |
2009年 | 113篇 |
2008年 | 109篇 |
2007年 | 91篇 |
2006年 | 101篇 |
2005年 | 90篇 |
2004年 | 73篇 |
2003年 | 51篇 |
2002年 | 61篇 |
2001年 | 49篇 |
2000年 | 58篇 |
1999年 | 67篇 |
1998年 | 88篇 |
1997年 | 79篇 |
1996年 | 61篇 |
1995年 | 66篇 |
1994年 | 48篇 |
1993年 | 40篇 |
1992年 | 44篇 |
1991年 | 43篇 |
1990年 | 34篇 |
1989年 | 42篇 |
1988年 | 27篇 |
1987年 | 34篇 |
1986年 | 33篇 |
1985年 | 28篇 |
1984年 | 32篇 |
1983年 | 29篇 |
1981年 | 30篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1978年 | 19篇 |
1977年 | 26篇 |
1976年 | 31篇 |
1975年 | 19篇 |
1974年 | 24篇 |
1973年 | 21篇 |
1971年 | 17篇 |
排序方式: 共有2765条查询结果,搜索用时 15 毫秒
1.
2.
Steffen Vojacek Lukas Schulig Nathalie Wössner Norman Geist Prof. Dr. Walter Langel Prof. Dr. Manfred Jung Prof. Dr. Dennis Schade Prof. Dr. Andreas Link 《ChemMedChem》2019,14(8):853-864
Indoles are privileged structures in medicinal and bioorganic chemistry that are particularly well suited to serve as platforms for diversity. Among many other therapeutic areas, the indole scaffold has been used to design aromatic compounds useful to interfere with enzymes engaged in the regulation of substrate acylation status, such as sirtuins. However, the planarity of the indole ring is not necessarily optimal for all target enzymes, especially when functionalization with aromatic side chains is required. Replacement of flat scaffolds by nonplanar molecular cores dominated by sp3 hybridization is a common strategy to avoid the disadvantages associated with poor solubility and high promiscuity, while covering less-well-explored areas of chemical space. Thus, we synthesized fragment-like tetrahydroindoles suitable for fragment-based drug discovery as well as a well-characterized small library intended as multipurpose screening compounds. For proof of principle, these compounds were screened against sirtuins 1–3, enzymes known to be addressable by indoles. We found that 2,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indole-3-carboxamides are potent and selective SIRT2 inhibitors. Compound 16 t displayed an IC50 value of 0.98 μm and could serve as exquisite starting point for hit-to-lead profiling. 相似文献
3.
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
4.
5.
Diese Recherche zeigt, dass sich die Bedeutung, die dem Thema RFID in den Medien und der ?ffentlichen Diskussion derzeit beigemessen
wird, auch in der Anzahl der im Internet zu findenden Seiten niederschl?gt. Dabei bewegt sich die Qualit?t der betrachteten
Angebote überwiegend auf einem hohen Niveau, was vor allem auf Seiten der kommerziellen Anbieter nicht weiter verwundert,
da es sich bei RFID doch um einen zunehmend st?rker umk?mpften Markt handelt, auf dem es hei?t, potenzielle Kunden für sich
zu akquirieren. Es darf mit Spannung erwartet werden, wie sich das Informationsangebot wandelt, wenn tats?chlich das prognostizierte
exponentielle Wachstum des RFID-Marktes eintritt. 相似文献
6.
The curing of diglycidyl ether of bisphenol A (DGEBA) with 2,6-dimethylol-p-cresol modified by hexahydrophthalic acid anhydride was investigated and compared with the analogous in situ curing of DGEBA, hexahydrophthalic acid anhydride and 2,6-dimethylol-p-cresol. The chemical reactions were investigated by means of titration and different spectroscopic and chromatographic methods. It was examined whether the less complicated and therefore cheaper in situ reaction delivers postcured products with equal or better properties. Furthermore, it was investigated whether the results are similar using technical phenolic hardeners. 相似文献
7.
JD Geiger 《Canadian Metallurgical Quarterly》1996,8(3):276-282
In order to characterize the role of transforming growth factor-alpha (TGF alpha) during hepatocarcinogenesis, liver tissue was examined at 10, 16, and 19 weeks following initial 10-week diethylnitrosamine (50 mg l-1 drinking water) exposure in female Wistar rats. Liver tissue protein extracts were electrophoresed and transferred to nitrocellulose filters. Levels of tissue-derived TGF alpha and epidermal growth factor receptor (EGFr) were assessed using an anti-TGF alpha monoclonal antibody (Ab-1) and an anti-EGFr polyclonal antibody (AB-4), coupled with scanning densitometric quantification. Immunolocalization of TGF alpha was performed in Bouin's-fixed, paraffin-embedded liver tissue sections. The distribution and intensity of TGF alpha immunoreactivity varied according to the degree of dysplasia, severely dysplastic cells being strongly immunoreactive. At week 10, mild hepatocyte dysplasia and perivenular inflammation were evident, together with a corresponding increase in perivenular TGF alpha immunoreactivity. By week 16, foci of moderate to severe dysplasia were observed; at this stage, there was a decrease in perivenular immunoreactivity but a further increase in overall liver tissue TGF alpha levels. Some 'altered foci' and dysplastic nodules showed intense immunoreactivity for TGF alpha. At these time points, immunodetectable liver EGFr was found to decrease significantly in comparison with normal control tissue. TGF alpha immunoreactivity was observed in fully developed carcinomas at week 19, although some tumours were negative by immunohistochemistry. The up-regulation of immunodetectable TGF alpha and the concomitant down-regulation of EGFr demonstrated positive (P < 0.01) and negative (P < 0.001) correlations, respectively, with hepatocyte proliferation indices. These findings suggest that the TGF alpha/EGFr ligand receptor system may be important during tumour promotion and in the stimulation of continued proliferation in hepatocellular carcinomas. 相似文献
8.
For this study, 194 respondents completed a biographical data sheet, the Templer (1970) Death Anxiety Scale and the Constantinople (1973) Inventory of Psychosocial Development to help assess the relationship among death anxiety, age, and psychosocial maturity. Findings showed that psychosocial maturity was a better predictor of death anxiety than age was. However, both variables were significantly negatively correlated with death anxiety, revealing that as psychosocial maturity and age increase, death anxiety decreases. 相似文献
9.
10.