全文获取类型
收费全文 | 430篇 |
免费 | 15篇 |
专业分类
化学 | 346篇 |
晶体学 | 7篇 |
力学 | 2篇 |
数学 | 29篇 |
物理学 | 61篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 30篇 |
2011年 | 28篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 27篇 |
2007年 | 11篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 14篇 |
2003年 | 14篇 |
2002年 | 18篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1963年 | 2篇 |
1962年 | 4篇 |
1960年 | 2篇 |
1956年 | 2篇 |
1955年 | 2篇 |
1952年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有445条查询结果,搜索用时 31 毫秒
71.
Harvey P Chalmers KH De Luca E Mishra A Parker D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(28):8748-8757
Paramagnetic magnetic resonance chemical shift probes containing a proximal CF(3) group have been characterised. Different systems have been created that report reversible changes in calcium ion concentrations in the millimolar regime, signal the presence of citrate selectively in competitive aqueous media and allow the monitoring of remote ester/amide hydrolysis in relayed, irreversible transformations. Chemical shift non-equivalence is amplified by the presence of the proximate lanthanide ion, with a mean separation between the CF(3) group and the metal ion of 6.4 ? found for a thulium complex, in an X-ray structure of the metal complex aqua adduct. The enhanced rate of longitudinal relaxation of the (19)F nucleus allows faster data acquisition. 相似文献
72.
73.
C Tyrsted KM Ornsbjerg Jensen ED Bøjesen N Lock M Christensen SJ Billinge B Brummerstedt Iversen 《Angewandte Chemie (International ed. in English)》2012,51(36):9030-9033
Supercritical growth: The formation and evolution of ceria nanoparticles during hydrothermal synthesis was investigated by in?situ total scattering and powder diffraction. The nucleation of pristine crystalline ceria nanoparticles originated from previously unknown cerium dimer complexes. The nanoparticle growth was highly accelerated under supercritical conditions. 相似文献
74.
Taft F Harmrolfs K Nickeleit I Heutling A Kiene M Malek N Sasse F Kirschning A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(3):880-886
Access of four new tumor specific folic acid/ansamitocin conjugates is reported that relies on a synthetic strategy based on the combination of mutasynthesis and semisynthesis. Two bromo‐ansamitocin derivatives were prepared by mutasynthesis or by a modified fermentation protocol, respectively, that served as starting point for the semisynthetic introduction of an allyl amine linker under Stille conditions. A sequence of standard coupling steps introduced the pteroic acid/glutamic acid/cysteine unit to the modified ansamitocins. All new derivatives, including those that are expected to be generated after internalization of the folic acid/ansamitocin conjugates into the cancer cell and reductive cleavage of the disulfide linkage showed good to strong antiproliferative activity (IC50 <10 nM ) for different cancer cell lines. Finally, the four conjugates were exposed to two cancer cell lines [cervix carcinoma, KB‐3‐1 (FR+) and lung carcinoma, A‐459 (FR?)], the latter devoid of the membrane‐bound folic acid receptor (FR?). All four conjugates showed strong antiproliferative activity for the FR+ cancer cell line but were inactive against the FR? cell line. The synthetic strategy pursued is based on the combination of mutasynthesis and semisynthesis and proved to be powerful for accessing new ansamitocin derivatives that are difficult to prepare by total synthesis. 相似文献
75.
The one-pot TiCl4 catalysed Diels–Alder/Mannich reaction of α-cyanoaminoacrylates with 2-silyloxy-1,4-butadienes gives 6-keto-3-azabicyclo[3.3.1]nonane-1-carboxylates. Reduction of the ketone and alkylation of the resultant alcohol gives 6-alkoxy-3-azabicyclo[3.3.1]nonanes mimicking the AE rings of a number of Delphinium and Aconitum alkaloids, with the same stereochemistry as the natural products. 相似文献
76.
Kirsten Eisentr?ger 《Monatshefte für Mathematik》2012,168(1):1-16
Let K be the function field of a variety of dimension ?? 2 over an algebraically closed field of odd characteristic. Then Hilbert??s Tenth Problem for K is undecidable. This generalizes the result by Kim and Roush from 1992 that Hilbert??s Tenth Problem for the purely transcendental function field ${{{\overline{\mathbb{F}}_p}}(t_1,t_2)}$ is undecidable when p?>?2. 相似文献
77.
Ohne Zusammenfassung 相似文献
78.
79.
Dr. Farah Benyettou Dr. Anjana Ramdas Nair Yaereen Dho Dr. Thirumurugan Prakasam Dr. Renu Pasricha Jamie Whelan Prof. Hassan Traboulsi Javed Mazher Prof. Kirsten C. Sadler Prof. Ali Trabolsi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5270-5279
Triphenylphosphine (TPP) surface-functionalized and F-108 Pluronic-stabilized gold nanoparticles (F-108@TPP-AuNPs) have been synthesized through a one-step approach, leading to well-defined (9.6±1.6 nm) and water-soluble nanoparticles by microwave heating an aqueous solution of TPP-AuICl in the presence of a Pluronic polymer under basic conditions. TPP release was negligible under physiological conditions, but enhanced significantly at an acidic pH (5.4) mimicking that of a cancer cell. Laser irradiation (532 nm) raised the temperature of an aqueous solution of F-108@TPP-AuNPs to 51.7 °C within 5 min, confirming efficient light-to-heat conversion capabilities without significant photodegradation. TEM confirmed intracellular localization of F-108@TPP-AuNPs in the cytosol, endosomes and lysosomes of HeLa cells. F-108@TPP-AuNPs were well tolerated by HeLa cells and zebrafish embryos at ambient temperatures and became toxic upon heat activation, suggesting synergistic interactions between heat and cytotoxic action by TPP. 相似文献
80.