全文获取类型
收费全文 | 406篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
化学 | 327篇 |
晶体学 | 3篇 |
数学 | 9篇 |
物理学 | 79篇 |
出版年
2022年 | 7篇 |
2021年 | 1篇 |
2019年 | 8篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2016年 | 9篇 |
2015年 | 14篇 |
2014年 | 3篇 |
2013年 | 18篇 |
2012年 | 26篇 |
2011年 | 29篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 33篇 |
2007年 | 18篇 |
2006年 | 25篇 |
2005年 | 35篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有418条查询结果,搜索用时 78 毫秒
291.
292.
Mengyu You Daisuke Sakakibara Kota Makino Yonosuke Morishita Kazutoshi Matsumura Yuta Kawashima Manao Yoshikawa Mahiro Tonosaki Kazutaka Kanno Atsushi Uchida Satoshi Sunada Susumu Shinohara Takahisa Harayama 《Entropy (Basel, Switzerland)》2022,24(11)
By numerical simulations and experiments of fully chaotic billiard lasers, we show that single-mode lasing states are stable, whereas multi-mode lasing states are unstable when the size of the billiard is much larger than the wavelength and the external pumping power is sufficiently large. On the other hand, for integrable billiard lasers, it is shown that multi-mode lasing states are stable, whereas single-mode lasing states are unstable. These phenomena arise from the combination of two different nonlinear effects of mode-interaction due to the active lasing medium and deformation of the billiard shape. Investigations of billiard lasers with various shapes revealed that single-mode lasing is a universal phenomenon for fully chaotic billiard lasers. 相似文献
293.
Yamato Kyouhei Yoshida Yutaka Kumamoto Yoshiaki Isogai Akira 《Cellulose (London, England)》2022,29(5):2839-2853
Cellulose - The carboxy groups abundantly and densely present on 2,2,6,6-tetramehylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers (TEMPO-CNFs) have been chemically modified to... 相似文献
294.
A new concept for improving the laser intensity distribution on an inertial confinement fusion target using a phase-controlled multi lens array has been proposed. Circular and hexagonal element lens apertures have been examined, and the circular aperture which eliminated azimuthally asymmetric intensity distribution was chosen. The diffraction fringe of the elementary lens was mitigated in a one-dimensional lens array using edge-shaped plates of a super-Gaussian phase profile. Uniform beam profiles were obtained using a one-dimensional array with 7 spherical lenses and a two-dimensional array with 37 lenses. An approximately flat-top intensity distribution was realized with the lens array with 37 lenses. 相似文献
295.
296.
297.
298.
Polyacrylamide gel electrophoresis (PAGE) is used frequently for isolation and purification of DNA fragments. In the present study, DNA fragments extracted from polyacrylamide gels showed significant band broadening in capillary electrophoresis (CE). A pHY300PLK (a shuttle vector functioning in Escherichia coli and Bacillus subtilis) marker, which contained nine fragments ranging from 80 to 4870 bp, was separated by PAGE, and each fragment was isolated by phenol/chloroform extraction and ethanol precipitation. After extraction from the polyacrylamide gel, the peaks of the isolated DNA fragments exhibited band broadening in CE, where a linear poly(ethylene oxide) was used as a sieving matrix. The theoretical plate numbers of the DNA fragments contained in the pHY300PLK marker were >106 for all the fragments before extraction. However, the DNA fragments extracted from the polyacrylamide gel showed decreased theoretical plate numbers (5–20 times smaller). The degradation of the theoretical plate number was significant for middle sizes of the DNA fragments ranging from 489 to 1360 bp, whereas the largest and smallest fragments (80 and 4870 bp) had no obvious influence. The band broadening was attributed to contamination of the DNA fragments by polyacrylamide fibers during the separation and extraction process. 相似文献
299.
Masamichi Nakayama Naoko Yamada Yoshikazu Kumashiro Hideko Kanazawa Masayuki Yamato Teruo Okano 《Macromolecular bioscience》2012,12(6):751-760
Thermoresponsive surfaces are prepared via a spin‐coating method with a block copolymer consisting of poly(N‐isopropylacrylamide) (PIPAAm) and poly(butyl methacrylate) (PBMA) on polystyrene surfaces. The PBMA block suppresses the removal of deposited PIPAAm‐based polymers from the surface. The polymer coating affects the temperature‐dependent cellular behavior of the surfaces with respect to protein adsorption. By adjusting layer thicknesses, PBMA‐b‐PIPAAm‐coated surfaces are optimized to regulate the adhesion/detachment of cells by temperature changes. Thus, thermoresponsive polymer‐coated surfaces are able to harvest contiguous cell sheets with their basal extracellular matrix proteins.
300.
Dr. Xin‐Long Ni Jun Tahara Dr. Shofiur Rahman Prof. Xi Zeng Dr. David L. Hughes Dr. Carl Redshaw Prof. Takehiko Yamato 《化学:亚洲杂志》2012,7(3):519-527
Heteroditopic hexahomotrioxacalix[3]arene receptors that are capable of binding an anion and a cation simultaneously in a cooperative fashion were synthesized. The structure of one of the triamide derivatives was confirmed by single‐crystal X‐ray diffraction. The binding of alkali metals at the lower rim, and the binding of anions (chloride, bromide) at the upper rim, has been investigated by using 1H NMR titration experiments. Alkali metal binding at the lower rim controls the calix cavity. Li+‐ion binding to the lower rim can improve the binding ability of anions at the upper rim amide moiety by a factor of 15, thus suggesting a strong positive allosteric effect for anion recognition. However, when a Na+ cation is bound to the ionophoric site on the lower rim, the calix cavity is changed from a “flattened cone” to a more‐upright form, which is favored for intramolecular hydrogen bonding between the neighboring NH and C?O groups; this change can block the inclusion of anions onto the amide moiety at the upper rim, which strongly suggests a negative allosteric effect of Na+‐ion binding, which controls the cooperative recognition system. 相似文献