全文获取类型
收费全文 | 1269篇 |
免费 | 91篇 |
国内免费 | 5篇 |
专业分类
化学 | 1084篇 |
晶体学 | 9篇 |
力学 | 8篇 |
数学 | 96篇 |
物理学 | 168篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 28篇 |
2020年 | 37篇 |
2019年 | 53篇 |
2018年 | 33篇 |
2017年 | 25篇 |
2016年 | 54篇 |
2015年 | 45篇 |
2014年 | 69篇 |
2013年 | 85篇 |
2012年 | 102篇 |
2011年 | 104篇 |
2010年 | 40篇 |
2009年 | 35篇 |
2008年 | 79篇 |
2007年 | 64篇 |
2006年 | 69篇 |
2005年 | 77篇 |
2004年 | 63篇 |
2003年 | 38篇 |
2002年 | 44篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 3篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1970年 | 2篇 |
1967年 | 3篇 |
排序方式: 共有1365条查询结果,搜索用时 15 毫秒
81.
Ewelina Lipiec Dr. Ryo Sekine Dr. Jakub Bielecki Prof. Dr. Wojciech M. Kwiatek Assoc. Prof. Bayden R. Wood 《Angewandte Chemie (International ed. in English)》2014,53(1):169-172
DNA double strand breaks (DSBs) are deadly lesions that can lead to genetic defects and cell apoptosis. Techniques that directly detect DNA DSBs include scanning electron microscopy, atomic force microscopy (AFM), and fluorescence based approaches. While these techniques can be used to identify DSBs they provide no information on the molecular events occurring at the break. Tip‐enhanced Raman scattering (TERS) can provide molecular information from DNA at the nanoscale and in combination with AFM provides a new way to visualize and characterize the molecular structure of DSBs. DSBs result from cleavage at the 3’‐ and 5’‐bonds of deoxyribose upon exposure to UVC radiation based on the observation of P? O? H and methyl/methylene deformation modes enhanced in the TERS spectra. It is hypothesized that strand fragments are hydrogen‐terminated at the lesion, indicating the action of free radicals during photon exposure. 相似文献
82.
Shuhei Uesugi Zhao Li Dr. Ryo Yazaki Prof. Dr. Takashi Ohshima 《Angewandte Chemie (International ed. in English)》2014,53(6):1611-1615
A highly chemoselective conjugate addition of alcohols in the presence of amines is described. The cooperative nature of the catalyst enabled chemoselective activation of alcohols over amines, allowing the conjugate addition to soft Lewis basic α,β‐unsaturated nitriles. Divergent transformation of the nitrile functionality highlights the utility of the present catalysis. 相似文献
83.
Kenji Shirokane Takamasa Wada Makoto Yoritate Ryo Minamikawa Nobuaki Takayama Dr. Takaaki Sato Prof. Dr. Noritaka Chida 《Angewandte Chemie (International ed. in English)》2014,53(2):512-516
A chemoselective approach for the total synthesis of (±)‐gephyrotoxin has been developed. The key to success was the utilization of N‐methoxyamides, which enabled the direct coupling of the amide with an aldehyde and selective reductive nucleophilic addition to the amide in the presence of a variety of sensitive and electrophilic functional groups, such as a methyl ester. This chemoselective approach minimized the use of protecting‐group manipulations and redox reactions, which resulted in the most concise and efficient total synthesis of (±)‐gephyrotoxin described to date. 相似文献
84.
Inside Back Cover: Size‐Selective Complexation and Extraction of Endohedral Metallofullerenes with Cycloparaphenylene (Angew. Chem. Int. Ed. 12/2014) 下载免费PDF全文
85.
Dr. Ryo Tsunashima Yoshifumi Iwamoto Yusuke Baba Chisato Kato Katsuya Ichihashi Dr. Sadafumi Nishihara Prof. Katsuya Inoue Prof. Katsuya Ishiguro Prof. Yu‐Fei Song Prof. Tomoyuki Akutagawa 《Angewandte Chemie (International ed. in English)》2014,53(42):11228-11231
In a mixed‐valence polyoxometalate, electrons are usually delocalized within the cluster anion because of low level of inter‐cluster interaction. Herein, we report the structure and electrical properties of a single crystal in which mixed‐valence polyoxometalates were electrically wired by cationic π‐molecules of tetrathiafulvalene substituted with pyridinium. Electron‐transport characteristics are suggested to represent electron hopping through strong interactions between cluster and cationic π‐molecules. 相似文献
86.
Protein kinase C (PKC) isozymes play central roles in signal transduction on the cell surface and could serve as promising therapeutic targets of intractable diseases like cancer, Alzheimer's disease, and acquired immunodeficiency syndrome (AIDS). Although natural PKC ligands like phorbol esters, ingenol esters, and teleocidins have the potential to become therapeutic leads, most of them are potent tumor promoters in mouse skin. By contrast, bryostatin‐1 (bryo‐1) isolated from marine bryozoan is a potent PKC activator with little tumor‐promoting activity. Numerous investigations have suggested bryo‐1 to be a promising therapeutic candidate for the above intractable diseases. However, there is a supply problem of bryo‐1 both from natural sources and by organic synthesis. Recent approaches on the synthesis of bryo‐1 have focused on its simplification, without decreasing the ability to activate PKC isozymes, to develop new medicinal leads. Another approach is to use the skeleton of natural PKC ligands to develop bryo‐1 surrogates. We have recently identified 10‐methyl‐aplog‐1 ( 26 ), a simplified analog of tumor‐promoting aplysiatoxin (ATX), as a possible therapeutic lead for cancer. This review summarizes recent investigations on the simplification of natural PKC ligands, bryo‐1 and ATX, to develop potential medicinal leads. 相似文献
87.
Junya Adachi Taizo Mori Ryo Inoue Masaya Naito Ngoc Ha‐Thu Le Soichiro Kawamorita Jonathan P. Hill Takeshi Naota Katsuhiko Ariga 《化学:亚洲杂志》2020,15(3):406-414
Molecular functions depend on conformations and motions of the corresponding molecular species. An air–water interface is a suitable asymmetric field for the control of molecular conformations and motions under a small applied force. In this work, double‐paddled binuclear PtII complexes containing pyrazole rings linked by alkyl spacers were synthesized and their orientations and emission properties dynamically manipulated at the air–water interface. The complexes emerge from water with concurrent variation of interface orientation of the planes of the PtII complexes from perpendicular to parallel during mechanical compression suggesting a unique ‘submarine emission‘. Phosphorescence of the complexes is quenched at the air–water interface prior to monolayer formation with intensities subsequently rapidly increasing during monolayer compression. These results indicate that asymmetric reactions and motions might be controlled by applying mechanical force at the air–water interface. 相似文献
88.
89.
90.
Simon Hu Hikari A.I. Yoshihara Robert Bok Jenny Zhou Minhua Zhu John Kurhanewicz Daniel B. Vigneron 《Magnetic resonance imaging》2012
Development of hyperpolarized technology utilizing dynamic nuclear polarization has enabled the measurement of 13C metabolism in vivo at very high signal-to-noise ratio (SNR). In vivo mitochondrial metabolism can, in principle, be monitored with pyruvate, which is catalyzed to acetyl-CoA via pyruvate dehydrogenase (PDH). The purpose of this work was to determine whether the compound sodium dichloroacetate (DCA) could aid the study of mitochondrial metabolism with hyperpolarized pyruvate. DCA stimulates PDH by inhibiting its inhibitor, pyruvate dehydrogenase kinase. In this work, hyperpolarized [1-13C]pyruvate and [2-13C]pyruvate were used to probe mitochondrial metabolism in normal rats. Increased conversion to bicarbonate (+ 181±69%, P=.025) was measured when [1-13C]pyruvate was injected after DCA administration, and increased glutamate (+ 74±23%, P=.004), acetoacetate (+ 504±281%, P=.009) and acetylcarnitine (+ 377±157%, P=.003) were detected when [2-13C]pyruvate was used. 相似文献