全文获取类型
收费全文 | 383篇 |
免费 | 20篇 |
专业分类
化学 | 249篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 87篇 |
物理学 | 54篇 |
出版年
2023年 | 1篇 |
2022年 | 11篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 17篇 |
2013年 | 29篇 |
2012年 | 21篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 18篇 |
2008年 | 33篇 |
2007年 | 16篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 24篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 3篇 |
排序方式: 共有403条查询结果,搜索用时 15 毫秒
91.
92.
Water‐Soluble Gold Nanoparticles: From Catalytic Selective Nitroarene Reduction in Water to Refractive Index Sensing
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Water‐soluble gold nanoparticles (Au NPs) stabilized by a nitrogen‐rich poly(ethylene glycol) (PEG)‐tagged substrate have been prepared by reduction of HAuCl4 with NaBH4 in water at room temperature. The morphology and size of the nanoparticles can be controlled by simply varying the gold/stabilizer ratio. The nanoparticles have been fully characterized by TEM, high‐resolution (HR) TEM, electron diffraction (ED), energy‐dispersive X‐ray spectroscopy (EDS), UV/Vis, powder XRD, and elemental analysis. The material is efficient as a recyclable catalyst for the selective reduction of nitroarenes with NaBH4 to yield the corresponding anilines in water at room temperature. Furthermore, the potential ability of the Au NPs as a refractive index sensor owing to their localized surface plasmon resonance (LSPR) effect has also been assessed. 相似文献
93.
Sergey Avgustinovich Sergey Kitaev Alexandr Valyuzhenich 《Discrete Applied Mathematics》2013,161(1-2):43-51
We introduce the notion of a boxed mesh pattern and study avoidance of these patterns on permutations. We prove that the celebrated former Stanley–Wilf conjecture is not true for all but eleven boxed mesh patterns; for seven out of the eleven patterns the former conjecture is true, while we do not know the answer for the remaining four (length-four) patterns. Moreover, we prove that an analogue of a well-known theorem of Erd?s and Szekeres does not hold for boxed mesh patterns of lengths larger than 2. Finally, we discuss enumeration of permutations avoiding simultaneously two or more length-three boxed mesh patterns, where we meet generalized Catalan numbers. 相似文献
94.
95.
Ilyn AP Loseva MV Vvedensky VY Putsykina EB Tkachenko SE Kravchenko DV Khvat AV Krasavin MY Ivachtchenko AV 《The Journal of organic chemistry》2006,71(7):2811-2819
We present a convenient synthesis of novel heteroaryl-fused 3-oxo-1,4-thiazepine-5-carboxamides and 5-oxo-1,4-thiazepine-3-carboxamides using a modification of four-component Ugi condensation. We demonstrate the usefulness and versatility of the developed approach for the synthesis of variously substituted compounds and discuss the scope and limitations of the chemistry involved. 相似文献
96.
It is proved that if a Schur superalgebra is not semisimple,then it is neither cellular nor quasi-hereditary (Theorem 2),and it has infinite global dimension (Corollary 18). The algebraS(m|n, r) with m, n 1 is semisimple if and only if p, the characteristicof the ground field, is zero or greater than r, or when m =n = 1 and p does not divide r. 2000 Mathematics Subject Classification17A70 (primary), 20C30 (secondary). 相似文献
97.
This paper deals with the search for optimal conditions for the identification of Transkarbam 12 (T 12) as a substance used for acceleration of transdermal penetration. Such substances are used in cases when drugs do not pass through the skin barrier under normal conditions. Other advantages are that they do not irritate the digestive system, provide continuous administration to an organism, and reduce fluctuations of drug concentration in blood. TLC and HPLC were used for identification. In the case of TLC, Silufol UV254 was used as stationary phase and the mobile phase consisted of chloroform, ethanol, and acetic acid. Detection was performed with iodine vapour. In the case of HPLC, the following three chromatographic columns were tested for the analysis of T 12: Silasorb SPH C 18, Silasorb SPH nitrile, and LiChrosorb Si-60. Because of the absence of any chromophore in the structure of T 12, work was performed on the derivatized compound. Detection was carried out at 230 nm. Quantification was studied on LiChrosorb Si-60 and the linearity, precision, and accuracy were evaluated. 相似文献
98.
Using the effective low frequency model of nematic medium we study the phase speeds and attenuations of the quasi-Rayleigh and Love waves in composite made of elastic core with the peripheral coating, as well as the fundamental S0 and A0 Lamb modes in heterogeneous plates. The analytical and numerical analysis revealed two types of unusual resonance effects disturbing wave propagation. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
99.
Alexandr N. Chernov Anna Tsapieva Diana A. Alaverdian Tatiana A. Filatenkova Elvira S. Galimova Mariia Suvorova Olga V. Shamova Alexander N. Suvorov 《Molecules (Basel, Switzerland)》2022,27(2)
Brain cancer treatment, where glioblastoma represents up to 50% of all CNS malignancies, is one of the most challenging calls for neurooncologists. The major driver of this study was a search for new approaches for the treatment of glioblastoma. We tested live S. pyogenes, cathelicidin family peptides and NGF, assessing the oncolytic activity of these compounds as monotherapy or in combination with chemotherapeutics. For cytotoxicity evaluation, we used the MTT assay, trypan blue assay and the xCELLigence system. To evaluate the safety of the studied therapeutic approaches, we performed experiments on normal human fibroblasts. Streptococci and peptides demonstrated high antitumor efficiency against glioma C6 cells in all assays applied, surpassing the effect of chemotherapeutics (doxorubicin, carboplatin, cisplatin, etoposide). A real-time cytotoxicity analysis showed that the cell viability index dropped to 21% 2–5 h after S. pyogenes strain exposure. It was shown that LL-37, PG-1 and NGF also exhibited strong antitumor effects on C6 glioma cells when applied at less than 10−4 M. Synergistic effects for combinations of PG-1 with carboplatin and LL-37 with etoposide were shown. Combinations of S. pyogenes strain #7 with NGF or LL-37 demonstrated a cytotoxic effect (56.7% and 57.3%, accordingly) on C6 glioma cells after 3 h of exposure. 相似文献
100.
Alexandr I. Alimpiev Valeri S. Gulev Pavel W. Mokruchniko 《Crystal Research and Technology》1995,30(3):295-297
The fields of crystallization in the system La2O3–BeO–Al2O3 are investigated. Single crystals of LaBeAl11O19 were grown by the Czochralski technique. 相似文献