全文获取类型
收费全文 | 360篇 |
免费 | 10篇 |
专业分类
化学 | 213篇 |
晶体学 | 8篇 |
力学 | 11篇 |
数学 | 31篇 |
物理学 | 107篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 33篇 |
2012年 | 24篇 |
2011年 | 25篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 14篇 |
2007年 | 25篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 17篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有370条查询结果,搜索用时 15 毫秒
91.
A novel synthesis of highly functionalized alkylsulfanylmethyl arenes 8a-m through the ring transformation of 6-aryl-4-methyl/ethylsulfanyl-2H-pyran-2-one-3-carbonitriles 1a-j, by reaction with methyl vinyl ketone 2, is delineated and illustrated. To ascertain the course of reaction, 3-arylsulfanylmethyl-2-methyl-6-methylsulfanyl-4-phenylbenzonitriles 8k-m were also prepared from the reaction of 1 with 4-arylsulfanyl-butan-2-ones 7c,d. 相似文献
92.
Choi YS Kim YK Shim JH Kim EM Kang HS Yoon do Y Muneta Y Myung PK 《Experimental & molecular medicine》2006,38(5):574-582
Xenotransplantation, the transplantation of cells, tissues or organs between individuals of different species, would resolve the current shortage of organs, but rejection remains the major hurdle to successful xenotransplantation. In the present study, we analyzed mixed lymphocyte reactions (MLRs) and used 51Cr release assays in order to identify the proliferation and expansion of mouse CD8+ cytotoxic T lymphocyte cells against PK15, PK15/pIL-18 or PK15/mIL-18 cells. In addition, we identified T cell populations in mouse splenocytes and lymph node cells using two-color flow cytometry. It was found that the CD8+ T cells of xenograft recipients proliferated extensively and that the survival rates of populations of PK15/mIL-18 or PK15/pIL-18 cells were higher than untransfected controls. Moreover, CD3+ T cells were increased in mice injected with PK15 cells or PK15/pIL-18 cells but PK15/pIL-18 cell numbers were lower in lymph nodes than untransfected controls. CD8+ T cells numbers were reduced in the lymph nodes of PK15/pIL-18 injected mice. These results suggest that porcine IL-18 regulates anti-pig cellular rejection in C57BL/6 mice. 相似文献
93.
[structure: see text] A new liquid crystalline material having an ethylenedioxythiophene-pyridazine-ethylenedioxythiophene (EDOT-PDZ-EDOT) core with two peripheral long alkyl chains was prepared. The designated donor-acceptor-donor (D-A-D)-type core structure induced a distinct smectic liquid crystalline phase due to the strong intermolecular interaction. The photophysical property and the layer structure of the liquid crystal were investigated by differential scanning calorimetry, polarized light microscopy, X-ray diffraction, and cyclic voltammetry. 相似文献
94.
Dalia Nayak Devdeep Mukherjee Aparna Banerjee Jhumpa Mukherjee 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):477-480
The present work discusses the complexation behavior of bioligand cysteine with cobalt and the immobilization of this complex
(Co–Cys) onto a biocompatible ligand and common drug base, polyvinylpyrrolidone (PVP). The complexation behavior has been
studied by radiometric method and UV–Vis spectrophotometry. The radiometric method involves dialysis of 60Co–Cys–PVP complex against triple distilled water which subsequently gives the dynamic dissociation constant (k
d) of the complex. The half life of 60Co–Cys–PVP complex calculated from k
d value is 22.6 h against triple distilled water at pH 8.5. The UV–Vis spectra analysis confirms the complexation of Co with
cysteine at this pH and also indicates that the cysteine ligated Co(II) centers easily get oxidised to Co(III) centers (low
spin, d6) in the presence of air at alkaline pH showing no d–d transitions. 相似文献
95.
Jung-Wook Kim Tae-Dong Kim Bok Sil Hong Oh Youn Kim Wan-Hee Yoon Chi-Bom Chae Yong Song Gho 《Experimental & molecular medicine》2010,42(7):514-523
Angiogenesis is critical and indispensable for tumor progression. Since VEGF is known to play a central role in angiogenesis, the disruption of VEGF-VEGF receptor system is a promising target for anti-cancer therapy. Previously, we reported that a hexapeptide (RRKRRR, RK6) blocked the growth and metastasis of tumor by inhibiting VEGF binding to its receptors. In addition, dRK6, the D-form derivative of RK6, retained its biological activity with improved serum stability. In the present study, we developed a serum-stable branched dimeric peptide (MAP2-dRK6) with enhanced anti-VEGF and anti-tumor activity. MAP2-dRK6 is more effective than dRK6 in many respects: inhibition of VEGF binding to its receptors, VEGF- and tumor conditioned medium-induced proliferation and ERK signaling of endothelial cells, and VEGF-induced migration and tube formation of endothelial cells. Moreover, MAP2-dRK6 blocks in vivo growth of VEGF-secreting colorectal cancer cells by the suppression of angiogenesis and the subsequent induction of tumor cell apoptosis. Our observations suggest that MAP2-dRK6 can be a prospective therapeutic molecule or lead compound for the development of drugs for various VEGF-related angiogenic diseases. 相似文献
96.
97.
J. H. Hamence K. M. Sil H. Huybrechts Ch. Degard M. N. Lu C. L. Dunn H. V. Tartar A. V. Pamfilov Elisabeth G. Ivanewa E. Schürmann K. Charisius H. Blumenthal E. S. Gawrilenko W. S. Kobsarenko H. Fischer Grete Leopoldi J. Golse J. H. Hastings H. F. Bradley und R. J. Mc Ilroy 《Fresenius' Journal of Analytical Chemistry》1935,100(3-4):125-132
Ohne Zusammenfassung 相似文献
98.
99.
Separation of enzymes by sequential macroaffinity ligand-facilitated three-phase partitioning 总被引:1,自引:0,他引:1
Pectinase and cellulase were separated from a commercial enzyme preparation called Pectinex Ultra SP-L. This was carried out using a process called macroaffinity ligand-facilitated three-phase partitioning (MLFTPP). In this method, a water-soluble polymer is floated as an interfacial precipitate by adding ammonium sulfate and tert.-butanol. The polymer (appropriately chosen) in the presence of an enzyme for which it shows affinity, selectively binds to the enzyme and floats as a polymer-enzyme complex. In the first step, pectinase was purified (with alginate as the polymer) 13-fold with 96% activity recovery. In the second MLFTPP step, using chitosan, cellulase was purified 16-fold with 92% activity recovery. Both preparations showed a single band on sodium dodecylsulfate-polyacrylamide gel electrophoresis. This illustrative example shows that the strategy of sequential MLFTPP can be used to separate important biological activities from a crude broth. 相似文献
100.
A Tolman-Bondi type inhomogeneous, spherically symmetric metric is obtained in an (n+2)-dimensional spacetime withn2. The metric form admits the familiar shell focusing singularity which, depending on the inhomogeneity parameter, may become naked. Moreover, for the particular case of a marginally bound collapsing model one may also obtain strong-curvature singularities, which provides yet another counterexample to the cosmic censorship hypothesis. It is interesting to point out that it is the assumption of self similarity rather than spherical symmetry which determines the nature of the singularity. This, however, extends an earlier observation of Lake and Zannias in four-dimensional spacetime. 相似文献