全文获取类型
收费全文 | 645篇 |
免费 | 19篇 |
专业分类
化学 | 516篇 |
晶体学 | 6篇 |
力学 | 1篇 |
综合类 | 2篇 |
数学 | 62篇 |
物理学 | 77篇 |
出版年
2023年 | 3篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 33篇 |
2012年 | 22篇 |
2011年 | 37篇 |
2010年 | 14篇 |
2009年 | 18篇 |
2008年 | 36篇 |
2007年 | 31篇 |
2006年 | 30篇 |
2005年 | 43篇 |
2004年 | 35篇 |
2003年 | 33篇 |
2002年 | 20篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 10篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1976年 | 19篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1971年 | 2篇 |
排序方式: 共有664条查询结果,搜索用时 0 毫秒
51.
Quantitative Detection for Porphyromonas gingivalis in Tooth Pocket and Saliva by Portable Electrochemical DNA Sensor Linked with PCR 下载免费PDF全文
Keiichiro Yamanaka Shinichi Sekine Takahiro Uenoyama Masahiro Wada Tomohiko Ikeuchi Masato Saito Yoshinori Yamaguchi Eiichi Tamiya 《Electroanalysis》2014,26(12):2686-2692
Here, a quantitative electrochemical analysis of periodontal bacteria in gingival crevicular fluid (GCF) and saliva by direct polymerase chain reaction (PCR) is presented. The electrochemical measurement was performed by mixing with PCR products and electrochemical indicator (bisbenzimidazole trihydrochloride). The peak current of indicator is reduced due to slower diffusion when the dye intercalates into the amplified DNA, and the degree of reduction in the peak current is correlates with the quantity of amplified DNA. Therefore, a quantitative analysis is possible by using our electrochemical method at the end point of PCR. In the GCF testing, The number of Porphyromonas gingivalis (Pg) detected by our electrochemical method at the end point of PCR were almost same compared with that were calculated by the conventional method of quantitative real? time PCR. In the saliva testing, the relationship between number of Pg in saliva and average pocket depth, and age‐dependence were also clearly observed. Since the saliva sample is obtained in a non‐invasive manner, this method is useful for the primary screening of periodontal disease. Moreover, our detection method is simple and uses a hand‐held potentiostat making it suitable for development of an on‐site periodontal diagnosis system. 相似文献
52.
Synthesis,Crystal Packing,and Ambipolar Carrier Transport Property of Twisted Dibenzo[g,p]chrysenes 下载免费PDF全文
Dr. Yasuyuki Ueda Dr. Hayato Tsuji Dr. Hideyuki Tanaka Prof. Dr. Eiichi Nakamura 《化学:亚洲杂志》2014,9(6):1623-1628
A versatile method for the synthesis of dibenzo[g,p]chrysene (DBC) derivatives based on regio‐ and stereoselective stannyllithiation to diarylacetylenes is described. This method affords a variety of DBCs possessing both electron‐donating and electron‐withdrawing functional groups. These twisted molecules take brickwork packing structures in single crystals. Thus, ambipolar carrier transport properties with mobility values of up to 10?3 cm2 V?1 s?1 in the amorphous state were achieved. Functional groups on DBC frameworks are considered to increase carrier mobility through the enhancement of intermolecular interactions in the brickwork packing structures. 相似文献
53.
Xiao Hui SU Gang LI Rui Sen LIN Eiichi KIKUCHI Masahiko MATSUKATA 《中国化学快报》2006,17(7):977-980
Zeolite membrane is an important category of inorganic membranes with many advantages such as thermal and chemical stability, high mechanical strength as well as the unique pore structure of molecular dimension. Up to now, many types of zeolite including … 相似文献
54.
In this study, we present the detection of tau protein, at room temperature, using a multi-spot localised surface plasmon resonance (LSPR)-based immunochip. To the best of our knowledge, this is the first report of an immunochip for tau protein. The detection method includes fabrication of a gold-capped nanoparticle LSPR chip, formation and functionalisation of a self-assembled monolayer (SAM), immobilisation of a suitable linker, effective blocking of non-specific adsorption, immobilisation of a monoclonal anti-tau antibody (tau-mAb), and finally, the optimum conditions for the immuno-reaction between tau-mAb and the antigen were determined. The method has a high performance, enables detection of tau at 10pg/mL, lower than the cut-off value of 195pg/mL (for AD) for tau protein in cerebral spinal fluid (CSF). Further, we demonstrated selectivity of the technique by showing that the introduction of bovine serum albumin (BSA), perhaps the most abundant protein component in serum and CSF, does not interfere with the detection of tau. This method also offers a potential platform for studying tau interactions with other proteins and/or potential drug candidates and could also be easily adapted for detecting phosphorylated tau and other AD biomarkers. 相似文献
55.
Wan-Feng Zhang Xiao-Ping Xia Takahashi Eiichi Li Li Qing Yang Yan-Qiang Zhang Ya-Nan Yang Ming-Liang Liu Chunkit Lai 《Surface and interface analysis : SIA》2020,52(5):224-233
Secondary ion mass spectrometry (SIMS) has a wide range of applications in Earth Science research, thanks to its high precision and sensitivity, and its capacity in direct insitu micromeasurement. The technique is operated in ultra-high vacuum (UHV) conditions, especially for the measurement of volatiles such as hydrogen, or the water content in nominally anhydrous minerals (NAMs). To minimize the water background and obtain accurate and precise water contents in NAMs (eg, olivine) critical parameters such as presputtering time, field aperture (FA), dynamic transfer on/off, and primary beam current intensity were investigated for a CAMECA IMS 1280-HR system. When the chamber vacuum reaches approximately 2 × 10−9 mbar, we set the DTOS OFF, raster size to 50 μm and primary beam current to 5 nA, and used 2000 μm FA and 170-second presputtering time. Consequently, an approximately 1.2 ppmw water background and 3.6 ppmw limit of detection (LOD) were yielded, from analyzing the San Carlos olivine. Meanwhile, the water content and homogeneity of a range of olivine minerals were characterized for potential use as reference materials for SIMS water content measurement. Olivine water content calibration curve was also established by comparing the Fourier transform infrared (FTIR) results with the SIMS-measured 16O1H−/16O− ratios. Accuracy and precision of water content measurement were estimated to be better than approximately 10% in this study. 相似文献
56.
Masahiko Matsukata Ken-ichi Sawamura Tsutomu Shirai Mitsuko Takada Yasushi Sekine Eiichi Kikuchi 《Journal of membrane science》2008,316(1-2):18-27
Controlling the growth of zeolite crystals on a porous alumina support is essential for preparing a compact zeolite membarne. First, mordenite seed crystals applied on a nonporous -alumina disk were grown and morphological change of mordenite crystals were observed in the course of growth. Then, mordenite membranes were synthesized on a porous -alumina tube under the same conditions employed in the study using the alumina disks. We found that seed crystal growth was widely controllable by changing water content in reaction solution, which resulted in better control of the morphology of mordenite crystals for synthesizing a thin compact mordenite membrane. Separation properties for mordenite membranes were studied in water–hydrogen binary system at 473 K with 10 kPa of water partial pressure, where no capillary condensation was expected in non-zeolitic pores. Separation factor for a mordenite membrane with a few defects was poor; however, a defect-free mordenite membrane prepared under a suitable condition highly separated steam from hydrogen. 相似文献
57.
Matsuo Y Muramatsu A Kamikawa Y Kato T Nakamura E 《Journal of the American Chemical Society》2006,128(30):9586-9587
A series of conical molecules featuring a [60]fullerene/ferrocene hybrid and five aralkyl side chains (Fe[C60{C6H4-(OCO-C6H3-(OR)2-3,4)-4}5]Cp) have been synthesized and examined for their structural and electrochemical properties as well as their ability to form supramolecular structures in crystals and liquid crystals. When the R group on the side is a methyl group, the compound forms crystals in which the dipolar conical molecules are stacked head-to-tail to form a columnar structure. When the R group is as long as a C18H38 group, the compound forms liquid crystals. Oxidation of the liquid crystalline compound by an aminium salt [(4-BrC6H4)3N][SbCl6] produces the corresponding paramagnetic Fe(III) compound that also exhibits liquid crystalline properties. 相似文献
58.
59.
Ulmann PA Tanaka H Matsuo Y Xiao Z Soga I Nakamura E 《Physical chemistry chemical physics : PCCP》2011,13(47):21045-21049
A [70]fullerene-benzodifuranone acceptor dyad synthesized by a Ag?-mediated coupling reaction was used to construct a thin-film organic solar cell. The fullerene and the benzodifuranone dye in the dyad have close-lying LUMO levels in the range of 3.7-3.9 eV, so that energy transfer from the dye to the fullerene can take place. A p-n heterojunction photovoltaic device consisting of a tetrabenzoporphyrin and a [70]fullerene-benzodifuranone dyad showed a weak but discernible contribution from light absorption of the dyad to the photocurrent under both a positive and a negative effective bias. These results indicate that the benzodifuranone moiety attached to the acceptor contributes to light-harvesting by energy transfer. 相似文献
60.
Selective flow-injection determination of methanol in the presence of ethanol based on a multi-enzyme system with chemiluminescence detection 总被引:2,自引:0,他引:2
Yoshiie Sekine
Masayasu Suzuki
Toshifumi Takeuchi Eiichi Tamiya Isao Karube 《Analytica chimica acta》1993,280(2):179-184A highly selective flow-injection system was developed for the determination of methanol. The system consisted of three immobilized enzymes with luminol chemiluminescence detection. First, methanol was oxidized in the presence of alcohol oxidase to yield formaldehyde and hydrogen peroxide. The hydrogen peroxide produced was then destroyed by catalase. The formaldehyde formed in the first stage was further oxidized by NAD+-formaldehyde dehydrogenase. The NADH formed was oxidized by 1-methoxy-5-methylphenazinium methylsulphate (1-MPMS), and finally the reduced 1-MPMS was spontaneously oxidized and hydrogen peroxide was produced. The concentration of the hydrogen peroxide produced, which was proportional to the initial concentration of methanol, was determined by luminol chemiluminescence. The determination range was from 0.1 to 100 mg l−1 and the response time was less than 2 min per sample with a relative standard deviation of less than 3%. The system showed good selectivity for methanol; the response was ca. 50 times higher than for ethanol. 相似文献