全文获取类型
收费全文 | 290篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
化学 | 193篇 |
晶体学 | 6篇 |
力学 | 5篇 |
数学 | 12篇 |
物理学 | 86篇 |
出版年
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 19篇 |
2011年 | 34篇 |
2010年 | 15篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 18篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1958年 | 2篇 |
排序方式: 共有302条查询结果,搜索用时 15 毫秒
71.
Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source 总被引:1,自引:0,他引:1
H. Bluhm K. Andersson T. Araki K. Benzerara G.E. Brown J.J. Dynes S. Ghosal M.K. Gilles H.-Ch. Hansen J.C. Hemminger A.P. Hitchcock G. Ketteler A.L.D. Kilcoyne E. Kneedler J.R. Lawrence G.G. Leppard J. Majzlam B.S. Mun S.C.B. Myneni A. Nilsson H. Ogasawara D.F. Ogletree K. Pecher M. Salmeron D.K. Shuh B. Tonner T. Tyliszczak T. Warwick T.H. Yoon 《Journal of Electron Spectroscopy and Related Phenomena》2006,150(2-3):86-104
We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally relevant samples. The experiments were performed at the molecular environmental science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(1 1 1) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river water biofilms, Al-containing colloids and mineral–bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e., with water or water vapor present at ambient temperature. 相似文献
72.
Soonbum Park Eun A Cho Jung Nyeo Chun Da Young Lee Sanghoon Lee Mi Yeon Kim Sang Mun Bae Su In Jo So Hee Lee Hyun Ho Park Tae Min Kim Insuk So Sang-Yeob Kim Ju-Hong Jeon 《Experimental & molecular medicine》2022,54(8):1225
Crizotinib is a clinically approved tyrosine kinase inhibitor for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harboring EML4-ALK fusion. Crizotinib was originally developed as an inhibitor of MET (HGF receptor), which is involved in the metastatic cascade. However, little is known about whether crizotinib inhibits tumor metastasis in NSCLC cells. In this study, we found that crizotinib suppressed TGFβ signaling by blocking Smad phosphorylation in an ALK/MET/RON/ROS1-independent manner in NSCLC cells. Molecular docking and in vitro enzyme activity assays showed that crizotinib directly inhibited the kinase activity of TGFβ receptor I through a competitive inhibition mode. Cell tracking, scratch wound, and transwell migration assays showed that crizotinib simultaneously inhibited TGFβ- and HGF-mediated NSCLC cell migration and invasion. In addition, in vivo bioluminescence imaging analysis showed that crizotinib suppressed the metastatic capacity of NSCLC cells. Our results demonstrate that crizotinib attenuates cancer metastasis by inhibiting TGFβ signaling in NSCLC cells. Therefore, our findings will help to advance our understanding of the anticancer action of crizotinib and provide insight into future clinical investigations.Subject terms: Non-small-cell lung cancer, Targeted therapies 相似文献
73.
Sung Phil Mun 《Molecules (Basel, Switzerland)》2022,27(24)
Pinus radiata bark is a rich source of polyphenols, which are mainly composed of proanthocyanidins. This study aimed to utilize P. radiata bark as a polyol source for bio-foam production in the future. Polyphenol-rich alkaline extracts (AEs) from P. radiata bark were prepared by mild alkaline treatment and then derivatized with propylene oxide (PO). Hydroxypropylated alkaline extracts (HAEs) with varying molar substitutions (MS 0.4–8.0) were characterized by FT-IR, NMR, GPC, TGA, and DSC. The hydroxyl value and solubility in commercial polyols were also determined. The molecular weights of the acetylated HAEs (Ac-HAEs) were found to be 4000 to 4900 Da. Analyses of FT-IR of HAEs and 1H NMR of Ac-HAEs indicated that the aromatic hydroxyl groups were hydroxypropylated and showed an increase in aliphatic hydroxyl group content. The glass transition temperature (Tg) of AE and HAEs were 58 to 60 °C, showing little difference. The hydroxyl value increased as the hydroxypropylation proceeded. Although salts were produced upon neutralization after hydroxypropylation, HAEs still showed suitable solubility in polyether and polyester polyols; HAEs dissolved well in polyether polyol, PEG#400, and solubility reached about 50% (w/w). This indicated that neutralized HAEs could be directly applied to bio-foam production even without removing salts. 相似文献
74.
Wookyoung Jang Do Yeon Kim Seok Joon Mun Jun Hee Choi Yoon Ho Roh Ki Wan Bong 《Journal of polymer science. Part A, Polymer chemistry》2022,60(11):1767-1777
Polyethylene glycol (PEG) hydrogel microparticles generated via stop-flow lithography can be utilized for efficient microparticle-based cell culture processes because of their high biocompatibility, the molecular diffusion capability in the gel structure, and the tunability of their shape and size. However, the typical functionalization process of PEG microparticles with cell-adhesion promoters has inevitable limitations, requiring additional linker molecules and the preconjugation of linkers to cell-adhesion promoters and microparticles. In this study, a simple and direct cell-adhesion promoter functionalization process of the PEG microparticles is presented by use of aza-Michael reaction between remnant unreacted acrylate groups in particles and amine groups in cell-adhesion promoters. On the basis of proposed process, particles are directly conjugated with poly-l -lysine (PLL), a typical cell-adhesion promoter that can electrostatically interact with cellular membranes, in a controllable manner. We demonstrate enhanced cell-adhesion capabilities of the particles along with the increased amount of conjugated PLL in the particles. Furthermore, to validate extended applicability, the particles are directly conjugated with Gly-Arg-Gly-Asp-Ser (GRGDS) peptides, in which RGD sequence is involved in the cell-adhesion behavior of extracellular matrix proteins, including fibronectin. The introduced GRGDS peptides increase the cell-adhesion capacity of the microparticles binding to integrin proteins in cellular membranes. 相似文献
75.
Interactions between linear and network polymers are studied in the case when one component is a polyacid and the other component
is an uncharged polymer. It is shown that, under different reaction conditions, swelling or contraction of the polymer network
can be observed for the same pair of reagents. It is found that, during consideration of the formation of an interpolymer
complex between network and linear polymers, a distinction should be made between a semi-interpenetrating network and a hydrogel
with a modified surface. The latter forms under conditions when the linear polymer practically does not penetrate the network
and the complexation occurs predominantly on the sample surface. 相似文献
76.
An efficient and scalable route for the synthesis of nitriles was developed by oxoammonium salt (4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate) mediated oxidative conversion of aldehydes with NH4OAc. A variety of aliphatic aldehydes as well as benzaldehydes were converted into the corresponding nitriles in high yields. The nitroxyl radical which is the reduced species of the used oxoammonium salt was recovered by simple acid-base extraction for the recycling. 相似文献
77.
Campbell GK Leanhardt AE Mun J Boyd M Streed EW Ketterle W Pritchard DE 《Physical review letters》2005,94(17):170403
A systematic shift of the photon recoil momentum due to the index of refraction of a dilute gas of atoms has been observed. The recoil frequency was determined with a two-pulse light grating interferometer using near-resonant laser light. The results show that the recoil momentum of atoms caused by the absorption of a photon is n variant Planck's k, where n is the index of refraction of the gas and k is the vacuum wave vector of the photon. This systematic effect must be accounted for in high-precision atom interferometry with light gratings. 相似文献
78.
Dae-Won Park Na-Young Mun Eun-Ha Lee Youngson Choe Sang-Wook Park 《Reaction Kinetics and Catalysis Letters》2006,89(1):149-156
Summary Selective ammoxidation of ethylene over Co-ZSM-5 prepared by aqueous and solid-state ion exchange has been studied. The catalyst
prepared using solid-state exchange showed higher activity and selectivity to acetonitrile. Catalysts tested in the ammoxidation
of ethylene were previously characterized by chemical analysis, XRD, N2-BET measurements and FTIR. TPD of ammonia and FTIR of pyridine used as probe molecule showed that solid-state ion exchange
of H-ZSM-5 with cobalt generates new Lewis acid sites which seem to play a role in the ammoxidation reaction. 相似文献
79.
2,3-Disubstituted indoles were synthesized by solid-phase reaction using the Fischer indole synthesis. A "traceless" silicon linker was employed with the silicon-carbon bonding being cleaved with TFA. An oxygen atom was placed into the middle of the spacer/linker so as to enhance solid-phase synthesis by better solvation. 相似文献
80.