全文获取类型
收费全文 | 783篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
化学 | 588篇 |
晶体学 | 21篇 |
力学 | 25篇 |
数学 | 72篇 |
物理学 | 101篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 31篇 |
2013年 | 47篇 |
2012年 | 49篇 |
2011年 | 59篇 |
2010年 | 35篇 |
2009年 | 28篇 |
2008年 | 51篇 |
2007年 | 38篇 |
2006年 | 37篇 |
2005年 | 45篇 |
2004年 | 44篇 |
2003年 | 29篇 |
2002年 | 38篇 |
2001年 | 31篇 |
2000年 | 34篇 |
1999年 | 29篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有807条查询结果,搜索用时 15 毫秒
91.
92.
Hae-Jung Chae Geum-Jin Kim Barsha Deshar Hyun-Jin Kim Min-Ji Shin Hyukbean Kwon Ui-Joung Youn Joo-Won Nam Sung-Hak Kim Hyukjae Choi Sung-Suk Suh 《Molecules (Basel, Switzerland)》2021,26(13)
Colorectal cancer is one of the life-threatening ailments causing high mortality and morbidity worldwide. Despite the innovation in medical genetics, the prognosis for metastatic colorectal cancer in patients remains unsatisfactory. Recently, lichens have attracted the attention of researchers in the search for targets to fight against cancer. Lichens are considered mines of thousands of metabolites. Researchers have reported that lichen-derived metabolites demonstrated biological effects, such as anticancer, antiviral, anti-inflammatory, antibacterial, analgesic, antipyretic, antiproliferative, and cytotoxic, on various cell lines. However, the exploration of the biological activities of lichens’ metabolites is limited. Thus, the main objective of our study was to evaluate the anticancer effect of secondary metabolites isolated from lichen (Usnea barbata 2017-KL-10) on the human colorectal cancer cell line HCT116. In this study, 2OCAA exhibited concentration-dependent anticancer activities by suppressing antiapoptotic genes, such as MCL-1, and inducing apoptotic genes, such as BAX, TP53, and CDKN1A(p21). Moreover, 2OCAA inhibited the migration and invasion of colorectal cancer cells in a concentration-dependent manner. Taken together, these data suggest that 2OCAA is a better therapeutic candidate for colorectal cancer. 相似文献
93.
94.
95.
96.
Jee‐Hyun Ryu Dong‐Oh Shin Kyung‐Do Suh 《Journal of polymer science. Part A, Polymer chemistry》2005,43(24):6562-6572
A reflective electrochromic device (ECD) based on polymeric microspheres was proposed, and its feasibility for a display was investigated. The viologen moiety was introduced onto the surface of chloro‐functionalized polymeric microspheres via refluxing in toluene. The existence of the viologen pendants was confirmed with X‐ray photoelectron spectroscopy, and their redox reactions were examined with cyclic voltammetry. The ECD had an inherent white background without an applied potential because the micrometer size range of the substrate particles scattered the light, whereas a deep violet color appeared when 3.0 V was applied to the cell. This color change could have been caused by the reduction of viologen pendants on the surface of the polymeric microspheres. The reflectance values of the ECD were observed with a spectrophotometer, and the response times and cyclic stability of the ECD, depending on the potential, were also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6562–6572, 2005 相似文献
97.
The purpose of this paper is to give a characterization of real hypersurfaces of type A0, A in a quaternionic hyperbolic space
QH
m by the covariant derivative of the second fundamental tensor.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
98.
Eunjae Jeong Sun Hee Kim In Hwan Jung Yangjun Xia Kwanghee Lee Hongsuk Suh Hong‐Ku Shim Han Young Woo 《Journal of polymer science. Part A, Polymer chemistry》2009,47(14):3467-3479
An indenofluorene‐based copolymer containing blue‐, green‐, and red light‐emitting moieties was synthesized by Suzuki polymerization and examined for application in white organic light‐emitting diodes (WOLEDs). Tetraoctylindenofluorene (IF), 2,1,3‐benzothiadiazole (BT), and 4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole (DBT) derivatives were used as the blue‐, green‐, and red‐light emitting structures, respectively. The number‐average molecular weight of the polymer was determined to be 25,900 g/mol with a polydispersity index of 2.02. The polymer was thermally stable (Td = ~398 °C) and quite soluble in common organic solvents, forming an optical‐quality film by spin casting. The EL characteristics were fine‐tuned from the single copolymer through incomplete fluorescence energy transfer by adjusting the composition of the red/green/blue units in the copolymer. The EL device using the indenofluorene‐based copolymer containing 0.01 mol % BT and 0.02 mol % DBT units ( PIF‐BT01‐DBT02 ) showed a maximum brightness of 4088 cd/m2 at 8 V and a maximum current efficiency of 0.36 cd/A with Commission Internationale de L'Eclairage (CIE) coordinates of (0.34, 0.32). The EL emission of PIF‐BT01‐DBT02 was stable with respect to changes in voltage. The color emitted was dependent on the thickness of the active polymer layer; layer (~60 nm) too thin was unsuitable for realizing WOLED via energy transfer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3467–3479, 2009 相似文献
99.
Tae Young Kim Tae Hee Lee Jong Eun Kim Rajeswari M. Kasi Chong S. P. Sung Kwang S. Suh 《Journal of polymer science. Part A, Polymer chemistry》2008,46(20):6872-6879
A nonaqueous dispersion of poly(3,4‐ethylenedioxythiophene) (PEDOT) was prepared with the use of polymeric ionic liquid (PIL) as a polymerization template and phase transfer medium. A detailed investigation was performed to understand the role of PIL in the course of polymerization and phase transfer reaction. On the basis of our findings from X‐ray photoelectric spectroscopy (XPS), we propose a mechanism by which the PIL leads to the nanostructured PEDOT colloids in various organic solvents and thus facilitating smoother surface morphologies of the PEDOT‐PIL films. In addition, the enhancement of charge transport was observed for PEDOT‐PIL complex when compared with PEDOT without PIL. Raman spectroscopy indicates that there is a reduced interaction between the charge carriers on the PEDOT and the counter ions bound to PIL, thus promoting charge carrier hopping rates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6872–6879, 2008 相似文献
100.