全文获取类型
收费全文 | 328篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
化学 | 218篇 |
晶体学 | 15篇 |
力学 | 7篇 |
数学 | 18篇 |
物理学 | 84篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 25篇 |
2013年 | 16篇 |
2012年 | 33篇 |
2011年 | 42篇 |
2010年 | 18篇 |
2009年 | 12篇 |
2008年 | 22篇 |
2007年 | 11篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 20篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有342条查询结果,搜索用时 0 毫秒
21.
Aram Hong Chang Min Choi Han Jun Eun Changseop Jeong Prof. Jiyoung Heo Prof. Nam Joon Kim 《Angewandte Chemie (International ed. in English)》2014,53(30):7805-7808
The CD spectroscopy of a chiral compound in solution yields an average CD value derived from all of the conformations of a chiral molecule. By contrast, CD spectroscopy of cold chiral molecules in the gas phase distinguishes specific conformers of a chiral molecule, but the weak CD effect has limited the practical application of this technique. Reported herein is the first resonant two‐photon ionization CD spectra of ephedrines in a supersonic jet using circularly polarized laser pulses, which were generated by synchronizing the oscillation of the photoelastic modulator with the laser firing. The spectra exhibited well‐resolved CD bands which were specific for the conformations and vibrational modes of each enantiomer. The CD signs and magnitudes of the jet‐cooled chiral molecules were very sensitive to their conformations and thus offered crucial information for determining the three‐dimensional structures of chiral species, as conducted in combination with quantum chemical calculations. 相似文献
22.
Ye Seul Kim Jung Won Yoon Dasol Kim Seunghak Choi Hyoung Kyu Kim Jae Boum Youm Jin Han Soon Chul Heo Sung-Ae Hyun Jung-Wook Seo Deok-Ho Kim Jae Ho Kim 《Experimental & molecular medicine》2022,54(4):493
Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) have been reported to exhibit immature embryonic or fetal cardiomyocyte-like phenotypes. To enhance the maturation of hESC-CMs, we identified a natural steroidal alkaloid, tomatidine, as a new substance that stimulates the maturation of hESC-CMs. Treatment of human embryonic stem cells with tomatidine during cardiomyocyte differentiation stimulated the expression of several cardiomyocyte-specific markers and increased the density of T-tubules. Furthermore, tomatidine treatment augmented the number and size of mitochondria and enhanced the formation of mitochondrial lamellar cristae. Tomatidine treatment stimulated mitochondrial functions, including mitochondrial membrane potential, oxidative phosphorylation, and ATP production, in hESC-CMs. Tomatidine-treated hESC-CMs were more sensitive to doxorubicin-induced cardiotoxicity than the control cells. In conclusion, the present study suggests that tomatidine promotes the differentiation of stem cells to adult cardiomyocytes by accelerating mitochondrial biogenesis and maturation and that tomatidine-treated mature hESC-CMs can be used for cardiotoxicity screening and cardiac disease modeling.Subject terms: Heart failure, Embryonic stem cells, Stem-cell differentiation 相似文献
23.
Park Chang Min Wang Dengjun Heo Jiyong Her Namguk Su Chunming 《Journal of nanoparticle research》2018,20(4):1-10
Journal of Nanoparticle Research - Utilizing solar energy for hydrogen evolution is a great challenge for its insufficient visible-light power conversion. In this paper, we report a facile... 相似文献
24.
Min Sang Park Seokwon Jung So Jeong Heo Seung Geol Lee 《Journal of Polymer Science.Polymer Physics》2017,55(19):1470-1479
An optical film with high optical anisotropy was prepared by the stretching of a cellulose acetate film and the consequential orienting of a retardation‐enhancing additive. The change in retardation in response to moisture absorption was explored and it was found that the degree of the retardation variation is strongly related to the stretching temperature. Stress generated by the stretching and its relaxation was systematically investigated to elucidate the effect of stretching temperature on the irreversible change in retardation upon moisture absorption. The results show that the magnitude of releasable stress plays an important role in controlling changes in optical properties. In addition, the difference in the deformation behavior between glassy and rubbery states should be taken into account in the development of a moisture‐resistant optical film. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1470–1478 相似文献
25.
Eunchan Jeong Joon Heo Dr. Sehoon Park Prof. Dr. Sukbok Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(25):6320-6325
While numerous organo(metallic)catalyst systems were documented for dearomative hydroboration of N-aromatics, alkoxide base catalysts have not been disclosed thus far. Described herein is the first example of alkoxide-catalyzed hydroboration of N-heteroaromatics including pyridines, providing a broad range of reduced N-heterocycles with high efficiency and selectivity. Mechanistic studies revealed an unprecedented counterintuitive dearomatization pathway, in which 1) pyridine-BH3 adducts undergo a hydride attack by alkoxyborohydrides, 2) in situ generated BH3 serves as a catalytic promoter, and 3) 1,4-dihydropyridyl borohydride is in a predominant resting state. 相似文献
26.
27.
Joung Heo 《Journal of Coordination Chemistry》2017,70(23):3837-3858
The reaction of [ZnCl2] with N-cyclopentyl-1-(quinolin-2-yl)methanimine (LA), N-cyclohexyl-1-(quinolin-2-yl)methanimine (LB), N-cyclohexyl-1-(pyridin-2-yl)methanimine (LC), 2,6-diethyl-N-(pyridin-2-ylmethylene)aniline (LD), N-cyclopentyl-1-(pyridin-2-yl)methanimine (LE), and N-phenyl-(pyridin-2-yl)methanimine (LF) in ethanol produced the bidentate [(NN′)ZnCl2] complexes, [LAZnCl2], [LBZnCl2], [LCZnCl2], [LDZnCl2], [LEZnCl2] and [LFZnCl2], respectively. The molecular structures revealed that the zinc in [LnZnCl2] (Ln = LA ? LD) showed a distorted tetrahedral geometry involving two nitrogens of N,N’-bidentate ligands and two chloride ligands. Most of these initiators were effective for polymerization of methyl methacrylate (MMA) and polymerization of rac-lactide (rac-LA). [LCZnCl2] (with N-cyclohexyl substituted at imine-pyridine moiety) exhibited the highest catalytic activity for MMA polymerization in the presence of modified methylaluminoxane (MMAO) with an activity of 3.33 × 104 g PMMA/mol·Zn·h at 60 °C, giving moderate syndiotactic poly methyl methacrylate (PMMA) with high molecular weight (9.62 × 105 g/mol). The dimethyl derivatives [LnZnMe2] (Ln = LA ? LF), generated in situ, polymerized rac-LA with moderate activity and yielded a polylactide (PLA) with good number-average molecular weights and narrower polydispersity indices (PDIs). [LAZnMe2] effectively initiates the ring-opening polymerization (ROP) of rac-LA to attain heterotactic PLA (Pr = 0.91). 相似文献
28.
Wook Jae Yoo Kyoung Won Jang Jeong Ki Seo Ji Yeon Heo Jin Soo Moon Jae Hoon Jun Jang-Yeon Park Bongsoo Lee 《Optical Review》2011,18(1):132-138
In this study, two types of nasal-cavity-attached fiber-optic respiration sensors have been fabricated for noninvasive respiratory
monitoring. One is a silver halide optical-fiber-based respiration sensor that can measure the variations of infrared radiation
generated by the respiratory airflow from a nasal cavity. The other is a thermochromic-pigment-based fiber-optic respiration
sensor that can measure the intensity of reflected light which changes owing to color variations of the temperature-sensing
film according to the temperature difference between inspiratory and expiratory air. We have demonstrated the similarities
of the respiratory signals using the fiber-optic respiration sensors and the temperature transducer of the BIOPAC? system.
In addition, we verified that respiratory signals without the deterioration of the MR image can be obtained using the fiber-optic
respiration sensors. It is anticipated that the proposed noninvasive fiberoptic respiration sensors will be highly effective
for respiratory monitoring of a patient during MRI procedures. 相似文献
29.
Eun Won Seo Ji Hee Han Cheol Ho Heo Prof. Dr. Jae Ho Shin Prof. Dr. Hwan Myung Kim Prof. Dr. Bong Rae Cho 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(39):12388-12394
Two‐photon microscopy (TPM) has become an indispensable tool in the study of biology and medicine due to the capability of this method for molecular imaging deep inside intact tissues. For the maximum utilization of TPM, a variety of two‐photon (TP) probes for specific applications are needed. In this article, we report a small‐molecule TP probe (ANO1) for nitric oxide (NO) that shows a rapid and specific NO response, a 68‐fold fluorescence enhancement in response to NO, and a maximum TP‐action cross‐section of 170 GM (GM: 10?50 cm4 photon?1) upon reaction with excess NO. This probe can be easily loaded into cells and tissues and can real‐time monitor NO in living tissues at 100–180 μm depth for longer than 1200 s through the use of TPM, with minimum interference from other biologically relevant species. 相似文献
30.