全文获取类型
收费全文 | 1022篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
化学 | 774篇 |
晶体学 | 11篇 |
力学 | 17篇 |
数学 | 23篇 |
物理学 | 219篇 |
出版年
2020年 | 8篇 |
2019年 | 10篇 |
2016年 | 14篇 |
2015年 | 18篇 |
2014年 | 21篇 |
2013年 | 37篇 |
2012年 | 42篇 |
2011年 | 55篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 60篇 |
2007年 | 38篇 |
2006年 | 45篇 |
2005年 | 40篇 |
2004年 | 39篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 29篇 |
2000年 | 17篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 17篇 |
1992年 | 16篇 |
1991年 | 21篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 19篇 |
1987年 | 27篇 |
1986年 | 13篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 26篇 |
1981年 | 21篇 |
1980年 | 18篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1972年 | 4篇 |
1971年 | 6篇 |
1968年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有1044条查询结果,搜索用时 0 毫秒
961.
Atsushi Kuwabara Shin-ichi Kuroda Hitoshi Kubota 《Plasma Chemistry and Plasma Processing》2008,28(2):263-271
We have finally succeeded in producing the plasma jet by use of the surface discharge plasma torch that can be expected to
make larger the diameter of torch in the comparatively easy way. It can be checked that the active species in the jet obtained
are different depending on the direction of connection, and also it was clearly found that much O and N2 is included in them. Consequently, etching was confirmed at the position of 10 mm from the torch end in the surface treatment
of polypropylene film, but etching was not confirmed at the position of 20 mm. 相似文献
962.
Measurement errors of color speckle are analyzed for a measurement system equipped with revolving XYZ filters and a 2D sensor. One of the errors is caused by the filter characteristics unfitted to the ideal color matching functions. The other is caused by uncorrelations among the optical paths via the XYZ filters. The unfitted color speckle errors of all the pixel data can be easily calibrated by conversion between the measured BGR chromaticity triangle and the true triangle obtained by the BGR wavelength measurements. For the uncorrelated errors, the measured BGR chromaticity values spread over around the true values. As a result, it would be more complicated to calibrate the uncorrelated errors, repeating the triangular conversion pixel by pixel. Color speckle and its errors greatly affect also chromaticity measurements and image quality of displays using coherent light sources. 相似文献
963.
Guo‐Qing Bian Takayoshi Kuroda‐Sowa Sayuri Sugimoto Masahiko Maekawa Megumu Munakata 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(3):m144-m146
The title one‐dimensional chain polymer complex, [Mn(C6H4NO3)Cl(C6H5N)2]n, was isolated from the reaction of MnCl2 with 6‐oxo‐1,6‐dihydropyridine‐2‐carboxylic acid (HpicOH) in pyridine. The asymmetric unit contains one [Mn(HPicO)Cl(py)2] moiety (py is pyridine), with the (HpicO)− ligand acting in a tridentate manner via the two carboxylate O atoms and the pyridone O atom. The operation of inversion centres generates eight‐ and 14‐membered rings and, in conjunction with an a‐axis translation, leads to an infinite chain extending along [100]. The Mn⋯Mn separations in this chain are 5.1069 (6) and 7.1869 (6) Å. The MnII atom has a distorted octahedral coordination, with trans‐axial pyridine ligands and with three O atoms and the Cl atom in the equatorial plane. The conformation of the 14‐membered ring is stabilized by pairs of inversion‐related N—H⋯O hydrogen bonds. 相似文献
964.
965.
Influence of gold- and carbon-coating on ToF-SIMS analysis of Cryptomeria japonica (Sugi) wood has been investigated to apply the samples after observing water distribution by cryo-scanning electron microscopy (cryo-SEM) or analyzing distribution of metal elements by SEM with energy dispersive X-ray spectrometer (SEM/EDX) to ToF-SIMS analysis to study the mechanism of heartwood formation of woody plants. The intensities of peaks at the m/z 285 ion in positive mode and the m/z 283 ion in negative mode from gold- and carbon-coated samples were compared with from those of non-coated samples. Those peaks were apparently attributable to ferruginol, a typical heartwood compounds in Sugi tree. From both gold- and non-coated samples, positive m/z 285 ions were generated. On the other hand, in negative mode, the intensity of m/z 283 ion was decreased after coating with gold. From carbon-coated samples, intensities of both positive m/z 285 ion and negative m/z 283 ion were decreased. These results suggest that the samples coated with gold for cryo-SEM could be applied to ToF-SIMS analysis directly to investigate the relation between water distribution and distribution of heartwood substances in heartwood-forming Sugi trees. However, non-coated samples should be used for SEM/EDX before analyzing by ToF-SIMS. 相似文献
966.
Tomoya Nishioka Kiyonori Kuroda Munetaka Akita Michito Yoshizawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6651-6655
A gemini‐type amphiphilic molecule, constituted of two V‐shaped polyaromatic amphiphiles linked by a linear acetylene spacer, was synthesized. The gemini amphiphile assembles into a well‐defined aromatic micelle (ca. 2 nm in core diameter), providing higher stability in water even at low concentration (0.09 mm ) and high temperature (>130 °C). Unlike common gemini amphiphiles with aliphatic chains, the present amphiphile and its micellar assembly emit green and orange fluorescence (ΦF=33 and 9 %), respectively. Despite strong and multiple π‐stacks of the polyaromatic panels of the amphiphiles, the water‐soluble gemini aromatic micelle incorporates medium‐size to large hydrophobic compounds into the frameworks. Interestingly, the guest binding capability toward large planar molecules was enhanced by more than two times through the pre‐encapsulation of spherical molecules in the cavity. 相似文献
967.
Yoshinori Saito Saori Iga Kie Hoshiyama Katsuyuki Nakashima Yasuko Okamoto Chiaki Kuroda Xun Gong Motoo Tori 《Tetrahedron》2019,75(14):2239-2245
Secobakkane B (C-6/C-7 cleaved secobakkane type aldehyde), secovirgaurenols B and C (C-8/C-9 cleaved secoeremophilane type), a 1β,10β-epoxyfuranoeremophilane, two 1β,10β-epoxyeremophilanolides, and fukinospirolide C (bakkane-type lactone), as well as 33 known compounds were isolated from three samples of Ligularia virgaurea collected in China. Two of the three analyzed samples were grouped in the neoadenostylone (N) type, and the rest, a mixture of the 6-hydroxyeuryopsyn (H) and cacalol (C) types, out of five chemotypes found in this species. 相似文献
968.
Ten lanostane glycosides (1-10), including two new norlanostane glycosides (2 and 7) and a new lanostane glycoside with a spirolactone ring system (9), were isolated from the fresh bulbs of Chionodoxa luciliae (Liliaceae). The structures of the new compounds were determined on the basis of extensive spectroscopic analysis and the results of hydrolytic cleavage to be (23S)-3beta-[(O-beta-D-apiofuranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl)oxy]-17alpha,23-epoxy-28,29-dihydroxy-27-norlanost-8-en-24-one (2), (23S)-17alpha,23-epoxy-29-hydroxy-3beta-[(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl)oxy]-27-norlanost-8-ene-15,24-dione (7), and (23S,25R)-17alpha,23-epoxy-29-hydroxy-3beta-[(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl)oxy]lanost-8-en-23,26-olide (9), respectively. The cytotoxic activity of the isolated compounds against HSC-2 human oral squamous cell carcinoma cells are also reported. 相似文献
969.
970.
Ibrutinib is an oral inhibitor of Bruton tyrosine kinase, which is one of the key drugs used for the treatment of chronic lymphocytic leukemia and mantle cell lymphoma. In this study, we aimed to develop a simple method for determining plasma ibrutinib concentration. The analysis required extraction of a 200 μL plasma sample and precipitation of proteins using solid‐phase extraction. Ibrutinib and nilotinib, which was used as an internal standard, were separated using high‐performance liquid chromatography (HPLC) using a mobile phase of acetonitrile–0.5% monopotassium phosphate (KH2PO4, pH 3.0; 52:48, v/v) on a Capcell Pack C18 MG II (250 × 4.6 mm) monitored at 260 nm, at a flow rate of 1.0 mL/min. The calibration curve was linear at the plasma concentration range of 10–500 ng/mL with a coefficient of determination (r2) of 0.9999. The coefficients of intra‐day and inter‐day validation were 4.0–6.6 and 2.6–7.7%, respectively. The assay accuracy was ?4.4–8.6%, and the recovery was >84%. This HPLC method coupled with ultraviolet (UV) detection for determining ibrutinib plasma concentration has several advantages such as simplicity and applicability to routine therapeutic drug monitoring at hospital laboratories. 相似文献