全文获取类型
收费全文 | 1004篇 |
免费 | 8篇 |
专业分类
化学 | 646篇 |
晶体学 | 9篇 |
力学 | 12篇 |
数学 | 42篇 |
物理学 | 303篇 |
出版年
2021年 | 8篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 21篇 |
2015年 | 14篇 |
2014年 | 16篇 |
2013年 | 30篇 |
2012年 | 37篇 |
2011年 | 46篇 |
2010年 | 34篇 |
2009年 | 28篇 |
2008年 | 51篇 |
2007年 | 50篇 |
2006年 | 38篇 |
2005年 | 44篇 |
2004年 | 35篇 |
2003年 | 44篇 |
2002年 | 53篇 |
2001年 | 31篇 |
2000年 | 37篇 |
1999年 | 13篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 19篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1968年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有1012条查询结果,搜索用时 15 毫秒
111.
[CpCo(oxddt)] complex (2, oxddt = o-xylenediyldithioethylene-1,2-dithiolate, Cp = η5-cyclopentadienyl) was obtained from o-xylenediyldithioethylene-1,3-dithiol-2-one (OC(oxddt)) (1). 2 further reacted with diazoalkanes (N2CHR) to form some alkylidene-bridged adducts [CpCo(CHR)(oxddt)] (R = H (3a), SiMe3 (3b)). Adduct 3a further reacted with protic acids (HX) to give some S-methylated adducts [CpCo(X)(oxddt)(S-Me)] (X = Cl (4a), OCOCF3 (4c)), followed by the Co-C bond cleavage in the three-membered cobaltathiirane ring. Two different Z-shaped and U-shaped molecular structures were observed by X-ray diffraction studies. In the former structure (Z), the dithiolene and o-xylylene planes are located at almost parallel position each other, and in the latter structure (U), both planes are not parallel but the o-xylylene moiety is located closer to the dithiolene plane than the Z-shaped one. The Z-shaped structure involves 1 and 2. The U-shaped structure involves 3a, 3b, 4a and 4c. Complex 1 showed a one-dimensional chain through intermolecular π-π interaction in the crystal. Complex 2 had a dimeric interaction between dithioethylenedithiolate moieties (S2C2S2) in the oxddt. The SiMe3 group in 3b was placed at an exo-position with respect to the cobaltadithiolene ring due to a steric hindrance from the U-shaped oxddt ligand. In 4a, the X and Me groups are located at the opposite side of the dithiolene plane (anti-form) but in 4c, both groups are presented at the same side of the dithiolene plane (syn-form). The NMR analysis of 4a in solution indicated existence of both anti- and syn-isomers (7:1). 相似文献
112.
Summary A simple, rapid and non-destructive technique has been devised for the detection of triazine herbicides by making use of the fluorescence inhibition properties of such compounds on fluorescing silica gel layers. The sensitivity of this method has been found to be increased up to 20 times in comparison to conventional spray techniques and approaches the detection limits obtained by radiochemical methods.
Zusammenfassung Ein einfaches, rasches, ohne Zerstörung der Probe durchführbares Verfahren zum Nachweis von Triazin-Herbiziden beruht auf deren Eigenschaft, die Fluoreszenz von Silicagelschichten zu löschen. Die Empfindlichkeit dieses Nachweisverfahrens ist bis zu 20mal besser als die üblicher Sprühverfahren und kommt damit rdiochemischen Methoden nahe.相似文献
113.
Thermal properties of organoindium thiolates were investigated by means of thermogravimetric (TG) and differential thermal (DT) analysis. Dibutyl-indium propylthiolates (Bun2InSPrn, Bun2InSPri, Bui2InSPrn and Bui2InSPri) decomposed up to 280°C along with an exothermic DT peak and gave indium(I) sulfide (InS) powders. Although the arylthiolate Bun2InSPh also afforded InS powders, it decomposed at a slightly higher temperature. In contrast, the dithiolate and the dithiocarbamate complexes [BunIn(SPri)2 and In (S2CNBu2)3] gave indium(III) sulfide (In2S3) powders. 相似文献
114.
Ken Okada Miyako Akiyoshi Atsumi Miyake Terushige Ogawa Mitsuo Nomura Takehiro Matsunaga 《Journal of Thermal Analysis and Calorimetry》2009,97(2):769-774
On January 21, 2003, an explosion occurred while ion exchange resin (IER) was being used to separate impurities from uranium
solution. To clarify the cause of the accident and go/no-go criteria of the explosion, elemental analysis of the IER, DSC
analysis, and SIKAREX analysis (a screening tool for runaway reactions) were performed. Finally, experiments on the same scale
as the accident were conducted in an explosion chamber. When HClO4 was added to IER-NO3, the IER violently exploded without any heating nor metal ions such as uranium. It was confirmed that the accident was caused
by an incorrect procedure in the chemical process. From the standpoint of explosion safety, IER-NO3 in particular should be kept away from perchloric acid in the laboratory. 相似文献
115.
Poly(2-vinylpyridine) or poly(4-vinylpyridine) coated on a piezoelectric quartz crystal adsorbed copper, thus decreasing the oscillation frequency. The bound copper could be removed by EDTA solution. Poly(4-vinylpyridine) is recommended to determine copper (5–35 μM) in a maleate buffer at pH 6.6 flowing over the coated crystal for 5 min. Iron(III) and cadmium interfered. 相似文献
116.
The diffusion of protons in porous media was observed and evaluated using a pH-imaging microscope with a flat semiconductor. Small particles were packed on the sensing surface of the flat sensor, followed by the addition of a lactic acid droplet on the top of the packed particle layer. The pH distribution accompanied by the diffusion of lactic acid was visualized at the bottom of the layer using the flat sensor. The difference in the diffusion property was confirmed depending on the particle type. The effective diffusion coefficients of the lactic acid in some porous media were estimated by combining the experimental results and mathematical calculation. 相似文献
117.
We confirmed that the light intensity (λ=785 nm) scattered from an isolated hemispherical Au nanoparticle was resonantly enhanced
at a diameter of 200 nm and a height of 50 nm, as observed experimentally using a collection-mode near-field optical microscope.
The experimental results agreed with the calculated results using Mie’s theory. Furthermore, we observed resonant energy transfer
of the optical near-field energy along a chain of Au nanoparticles. The magnitude of the transferred energy increased resonantly
at the size of resonant light scattering for an isolated Au nanoparticle (200 nm diameter with 240 nm center-to-center separation).
PACS 42.82.Et; 73.20.Mf; 78.67.Bf 相似文献
118.
Archiv der Mathematik - Let L / k be a Galois extension with Galois group G, and $(varepsilon ): 1to Ato Eto Gto 1$ a central extension. We study the existence of the Galois extension M / L /... 相似文献
119.
Optical Review - Increasing efficiency and productivity in the field of agriculture is important to provide sufficient food to the world’s increasing population. It is important to monitor... 相似文献
120.
We study the size dependence of the nonlinear response of weakly confined excitons for the size region beyond the long wavelength approximation regime. The observed degenerate-four-wave mixing signal of GaAs thin layers exhibits an anomalous size dependence, where the signal is resonantly enhanced at a particular thickness region. The theoretical analysis elucidates that this enhancement is due to the size-resonant enhancement of the internal field with a spatial structure relevant to the nondipole-type excitonic state. These results establish the formerly proposed new type of size dependence of nonlinear response due to the nonlocality induced double resonance. 相似文献