全文获取类型
收费全文 | 526篇 |
免费 | 8篇 |
专业分类
化学 | 264篇 |
晶体学 | 6篇 |
力学 | 13篇 |
数学 | 19篇 |
物理学 | 232篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2018年 | 3篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 33篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 25篇 |
2007年 | 24篇 |
2006年 | 30篇 |
2005年 | 23篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 20篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1966年 | 2篇 |
1958年 | 2篇 |
1928年 | 2篇 |
1917年 | 2篇 |
排序方式: 共有534条查询结果,搜索用时 15 毫秒
531.
The preparation and x-ray structure of [P(C2H5)4]+[N3]− and the attempted preparation of [PH4]+[N3]−
Thomas M. Klaptke Axel Schulz Peter S. White Margaret J. Crawford 《Heteroatom Chemistry》1998,9(2):129-132
Tetraethylphosphonium azide, [P(C2H5)4 ]+[N3 ]−, was prepared from tetraethyl phosphonium bromide and silver azide. Single crystals of [P(C2H5)4 ]+[N3 ]− were grown from dichloromethane/THF (10:1) solution. The structure was determined by single-crystal X-ray diffraction analysis. [P(C2H5)4 ]+[N3 ]− crystallizes in the monoclinic space group C 2/c with Z = 4 and unit cell dimensions a = 12.961(6), b = 6.835(3), c = 12.378(6) Å, and β = 100.57(4)°. The attempted preparation of phosphonium azide [PH4]+[N3]− from phosphonium iodide and silver azide lead instead to the formation of PH3 and HN3. The instability of [PH4]+[N3]− with respect to PH3 and HN3 is in accord with thermodynamic considerations according to which the reaction PH3(g) and HN3(g) to yield [PH4 ]+[N3 ]− is thermodynamically unfavorable. (Non SI units employed: kcal ≈ 4.184 J, Å = 10−10 m.) © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:129–132, 1998 相似文献
532.
The effects of crosslink functionality (fc), molecular weight between crosslinks (Mc), and chain stiffness display on the thermal and mechanical behavior of epoxy networks are determined. Both fc and Mc are controlled by blending different functionality amines with a difunctional epoxy resin. Chain stiffness is controlled by changing the chemical structure of the various amines. In agreement with rubber elasticity theory, the rubbery moduli are dependent on fc and Mc, but independent of chain stiffness. The glassy moduli and secondary relaxations of these networks are relatively independent of fc, Mc, and chain stiffness. However, the glass transition temperatures (Tg) of these networks are dependent on all three structural variables. This trend is consistent with free volume theory and entropic theories of Tg. fc, Mc, and chain stiffness control the yield strength of these networks in a manner similar to that of Tg and is the result that both properties involve flow or relaxation processes. Fracture toughness, as measured by the critical stress intensity factor (KIc), revealed that fc and Mc are both critical parameters. The fracture behavior is the result of the fracture toughness being controlled by the ability of the network to yield in front of the crack tip. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1371–1382, 1998 相似文献
533.
Dr. Zahra Rashidijahanabad Prof. Dr. Sherif Ramadan Nicholas A. O'Brien Athar Nakisa Dr. Shuyao Lang Dr. Howard Crawford Dr. Jeffrey C. Gildersleeve Prof. Dr. Xuefei Huang 《Angewandte Chemie (International ed. in English)》2023,62(47):e202309744
Sialyl Lewisa (sLea), also known as cancer antigen 19-9 (CA19-9), is a tumor-associated carbohydrate antigen. The overexpression of sLea on the surface of a variety of cancer cells makes it an attractive target for anticancer immunotherapy. However, sLea-based anticancer vaccines have been under-explored. To develop a new vaccine, efficient stereoselective synthesis of sLea with an amine-bearing linker was achieved, which was subsequently conjugated with a powerful carrier bacteriophage, Qβ. Mouse immunization with the Qβ-sLea conjugate generated strong and long-lasting anti-sLea IgG antibody responses, which were superior to those induced by the corresponding conjugate of sLea with the benchmark carrier keyhole limpet hemocyanin. Antibodies elicited by Qβ-sLea were highly selective toward the sLea structure, could bind strongly with sLea-expressing cancer cells and human pancreatic cancer tissues, and kill tumor cells through complement-mediated cytotoxicity. Furthermore, vaccination with Qβ-sLea significantly reduced tumor development in a metastatic cancer model in mice, demonstrating tumor protection for the first time by a sLea-based vaccine, thus highlighting the significant potential of sLea as a promising cancer antigen. 相似文献
534.
Esther Oger Nathan R. M. Crawford Rebecca Kelting Patrick Weis Manfred M. Kappes Reinhart Ahlrichs 《ChemInform》2008,39(7):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献