全文获取类型
收费全文 | 87篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 50篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 4篇 |
物理学 | 30篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 8篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1927年 | 2篇 |
排序方式: 共有88条查询结果,搜索用时 15 毫秒
31.
Novel cellulose-based bioplastics, mainly using inedible plant resources, were produced by bonding cellulose diacetate (CDA), a modified cardanol, and additional aliphatic and aromatic components. Cardanol is a phenol derivative with a linear unsaturated hydrocarbon side chain (carbon number: 15), derived from cashew nut shells. Esterification of the modified cardanol (3-pentadecylphenoxy acetic acid: PAA) and CDA resulted in a thermoplastic PAA-bonded CDA with high tenacity (long elongation while keeping maximum bending strength), heat resistance, and water resistance. These properties were better than those of a conventional CDA composite consisting of CDA and a conventional plasticizer. By comparing the PAA-bonded CDA with a CDA bonded with stearic acid (SA), which has a linear structure similar to that of PAA’s side chain but has no phenyl part, it was suggested that the linear side chain in PAA has a main role in these prominent properties of the PAA-bonded CDA, while the phenyl part in PAA has pronounced effects on its maximum bending strength and water resistance. Additional bonding of linear alkanoic acids, especially SA as aliphatic components improved the PAA-bonded CDA’s impact strength, and additional bonding of benzoic acid (BA) as an aromatic component further increased its maximum bending strength and elastic modulus. These components improved the thermoplasticity and water resistance of the PAA-bonded CDA while maintaining its high heat resistance relatively well. 相似文献
32.
Toyama M Hironaka M Yamahama Y Horiguchi H Tsukada O Uto N Ueno Y Tokunaga F Seno K Hariyama T 《Photochemistry and photobiology》2008,84(4):996-1002
There are two types of visual pigments in fish eyes; most marine fishes have rhodopsin, while most freshwater fishes have porphyropsin. The biochemical basis for this dichotomy is the nature of the chromophores, retinal (A1) and 3-dehydroretinal (A2), each of which is bound by an opsin. In order to study the regional distribution of these visual pigments, we performed a new survey of the visual pigment chromophores in the eyes of many species of fish. Fish eyes from 164 species were used to examine their chromophores by high-performance liquid chromatography--44 species of freshwater fish, 20 of peripheral freshwater fish (coastal species), 10 of diadromous fish and 90 of seawater fish (marine species) were studied. The eyes of freshwater fish, limb freshwater fish and diadromous fish had both A1 and A2 chromophores, whereas those of marine fish possessed only A1 chromophores. Our results are similar to those of previous studies; however, we made a new finding that fish which live in freshwater possessed A1 if living near the sea and A2 if living far from the sea if they possessed only one type of chromophore. 相似文献
33.
34.
Y. Sobajima S. Nakano M. Nishino Y. Tanaka T. Toyama H. Okamoto 《Journal of Non》2008,354(19-25):2407-2410
Microstructures of microcrystalline silicon (μc-Si) deposited at a high-growth-rate have been investigated in order to apply to the photovoltaic i-layer. μc-Si films were prepared by very-high-frequency (100 MHz) plasma-enhanced chemical vapor deposition at 180 °C. High growth rates of 3.3–8.3 nm/s have been achieved utilizing high deposition pressures up to 24 Torr and large input powers. Applying μc-Si to n–i–p junction solar cells, as the optimum result in this experimental series, a conversion efficiency of 6.30% (JSC: 22.1 mA/cm2, VOC: 0.470 V, and FF: 60.7%) has been achieved employing the i-layer deposited at 8.1 nm/s. Raman scattering and X-ray diffraction measurements revealed the crystalline volume fraction of around 50% with the (2 2 0) crystallographic preferential orientation, respectively. The cross-sectional transmission electron microscope image shows densely columnar structure grown directly on the underlying n-layer. These structural features are basically in good agreement those of low-growth-rate μc-Si used for a high efficiency solar cell as previously reported, implying advantages of the use of high pressures with regard to providing the photovoltaic i-layers. Finally, the implication is discussed from the photovoltaic performance as a function of the crystalline volume fraction of i-layer, and current problems in improving the photovoltaic performance are extracted. 相似文献
35.
在原子能院串列加速器上,利用束箔方法,测量了能量为30 MeV Fe离子产生的高剥离态谱线跃迁结构的寿命值.在30 MeV时,Fe通过箔膜的电荷态分布在7+到17+,我们选择Fe XⅥ2p~6(~1S)4p—2p~6(~1S)5d(~2P_(3/2)~o—~2D_(3/2))的谱线,谱线波长124.696(?),能级寿命为79±4 ps.最后对实验误差进行了分析. 相似文献
36.
HE Cheng LIN Hao DO U Jun-mei MU Yun-dong 《数学季刊》2014,(2):159-166
It is known that the problem of minimizing total weighted completion time on a series-batching machine is NP-hard. We consider a series-batching bicriteria scheduling problem of minimizing makespan and total weighted completion time with equal length job simultaneously. A batching machine can handle up to b jobs in a batch, where b is called the batch capacity of the machine. We study the unbounded model with b≥n, where n denotes the number of jobs. A dynamic programming algorithm is proposed to solve the unbounded model, which can find all Pareto optimal schedules in O(n3) time. 相似文献
37.
In the course of our searching for anti-HIV agents from natural sources, we have isolated a triterpene and a doubly linked proanthocyanidin dimer as HIV-1 protease inhibitors from the wood of Xanthoceras sorbifolia Bunge (Sapindaceae)1. Further investigation of this plant has led to the isolation of a protoilludane sesquiterpene (1). The present paper describes the isolation and structural determination of this novel sesquiterpene. The EtOH eluate of a MeOH extract of the wood of X. so… 相似文献
38.
Time-resolved electron paramagnetic resonance (TREPR) spectra are presented for a phenanthrene-linked copper(II)-free-base porphyrin dimer. In the lowest electronic excited state, the free-base half is in the (π, π*) triplet state and the copper-porphyrin half is in the doublet ground state due to the copper(II) spin. Because of the interaction between the triplet and doublet spins, the excited state of the dimer is described as a coupled triplet-doublet pair state. By choosing the excitation wavelength, this coupled state is produced via either the intersystem crossing within the free base or the energy transfer from the excited state of the copper porphyrin. The observed TREPR spectra show very large spectral widths compared to that of the triplet state in the free-base monomer. In addition, there is a prominent absorptive band in the center of the spectra regardless of the generation pathway. These features can be interpreted as characteristic properties in an intermediate-coupling case, where the degree of the triplet and doublet mixing largely depends on the molecular orientation relative to the magnetic field. 相似文献
39.
Hideo Toyama Makiko Yano Akane Gisushi Takeshi Hotta Nobuo Toyama 《Applied biochemistry and biotechnology》2003,108(1-3):821-824
Cellulase hyperproducers of Trichoderma reesei can be constructed using autopolyploidization and haploidization techniques. To increase the efficiency of this method, the
active nuclear shuffling system in a swollen conidium was effective. A dried mature green conidium of a model strain, T. reesei QM6a (IFO 31326), was swollen to make room for a larger autopolyploid nucleus. After colchicine treatment, a larger autopolyploid
nucleus was produced in such a swollen conidium. Benomyl treatment of swollen conidia generated multiple smaller nuclei from
one larger autopolyploid nucleus. Those smaller nuclei were transported through conidia to mycelia after germination. This
system could contribute to increasing the efficiency of genetic shuffling. 相似文献
40.
Hideo Toyama Makiko Yano Takeshi Hotta 《Applied biochemistry and biotechnology》2004,114(1-3):325-334
The cellulolytic fungus, Trichoderma has oval and mononucleate conidia. When these conidia are incubated in a liquid medium, they begin to swell and their shape
becomes spherical followed by an increase in inner space. In such swollen conidia, it is possible to produce a larger autopolyploid
nucleus using a mitotic arrester compared with the case of the original conidia. In this study, polykaryon formation was attempted
using these swollen conidia. Dried mature green conidia of Trichoderma reesei QM6a (IFO 31326) were incubated in Mandel's medium in order to swell. The swollen conidia were treated with a mitotic arrester,
colchicine, for autopolyploidization. After autopolyploidization, polykary on formation was carried out using the swollen
conidia. After the treatment, multiple smaller nuclei whose diameter was almost the same as that of the original strain were
generated from an autopolyploid nucleus in a swollen conidium. A cellulase hyperproducer without decrease in growth rate could
be selected using such swollen conidia. 相似文献