全文获取类型
收费全文 | 3321篇 |
免费 | 115篇 |
国内免费 | 7篇 |
专业分类
化学 | 2235篇 |
晶体学 | 49篇 |
力学 | 123篇 |
数学 | 340篇 |
物理学 | 696篇 |
出版年
2023年 | 24篇 |
2022年 | 64篇 |
2021年 | 71篇 |
2020年 | 74篇 |
2019年 | 62篇 |
2018年 | 59篇 |
2017年 | 59篇 |
2016年 | 119篇 |
2015年 | 93篇 |
2014年 | 138篇 |
2013年 | 205篇 |
2012年 | 289篇 |
2011年 | 270篇 |
2010年 | 178篇 |
2009年 | 149篇 |
2008年 | 218篇 |
2007年 | 212篇 |
2006年 | 192篇 |
2005年 | 142篇 |
2004年 | 135篇 |
2003年 | 105篇 |
2002年 | 110篇 |
2001年 | 57篇 |
2000年 | 56篇 |
1999年 | 24篇 |
1998年 | 19篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 16篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1974年 | 6篇 |
1973年 | 6篇 |
排序方式: 共有3443条查询结果,搜索用时 15 毫秒
101.
Chromatographia - Optimal derivatization conditions were established for the simultaneous determination of 12 aliphatic saturated aldehydes, 8 aliphatic saturated ketones, 4 cyclic ketones, 3... 相似文献
102.
Yong‐beom Lim Dr. Myongsoo Lee Prof. 《Angewandte Chemie (International ed. in English)》2009,48(19):3394-3396
Available in small print : Block copolymer lithography has great potential for reducing the size and fabrication time of integrated circuits. Hydrogen‐bonding‐mediated molecular recognition in self‐assembly processes can be used to produce highly ordered square arrays of block copolymers on the surface of a silicon substrate (see picture).
103.
A. V. M. Chandramalar Y. Y. Lim Y. K. Leong 《Colloids and surfaces. A, Physicochemical and engineering aspects》1999,160(3):49-205
The effects of cis- and trans-1,2-, trans-1,4-cyclohexanedicarboxylic acid, 95% cis-1,3,5-cyclohexane tricarboxylic acid and cis-1,2,3,4,5,6-cyclohexanehexacarboxylic acid on the yield stress–pH behaviour of concentrated ZrO2 dispersions are reported. Adsorbed cis-1,2,3,4,5,6-cyclohexanehexacarboxylic acid imparts predominantly steric interactions. It forms a steric barrier keeping the interacting particles apart. Adsorbed cis- and trans-1,2 increase the maximum yield stress and this was attributed to a hydrophobic force resulting from the part of the cyclohexane ring sticking out into the solution which is devoid of charged or hydrophilic group. Adsorbed trans-1,4 increases the maximum yield stress by at least threefold and its configuration favours strong bridging interaction with an adjacent particle. Predominantly, cis-1,3,5 also increases the maximum yield stress but only by 60% at the same additive concentration. This was attributed to a smaller degree of bridging. 相似文献
104.
Lee S Park J Ragan R Kim S Lee Z Lim do K Ohlberg DA Williams RS 《Journal of the American Chemical Society》2006,128(17):5745-5750
Self-assembled monolayers (SAMs) of octanethiol and benzeneethanethiol were deposited on clean Pt(111) surfaces in ultrahigh vacuum (UHV). Highly resolved images of these SAMs produced by an in situ scanning tunneling microscope (STM) showed that both systems organize into a super-structure mosaic of domains of locally ordered, closely packed molecules. Analysis of the STM images indicated a (square root 3 x square root 3)R30 degrees unit cell for the octanethiol SAMs and a 4(square root 3 x square root 3)R30 degrees periodicity based on 2 x 2 basic molecular packing for the benzeneethanethiol SAMs under the coverage conditions investigated. SAMs on Pt(111) exhibited differences in molecular packing and a lower density of disordered regions than SAMs on Au(111). Electron transport measurements were performed using scanning tunneling spectroscopy. Benzeneethanethiol/Pt(111) junctions exhibited a higher conductance than octanethiol/Pt(111) junctions. 相似文献
105.
Jeon SM Jung SJ Lim do K Kim HD Lee H Kim S 《Journal of the American Chemical Society》2006,128(19):6296-6297
The adsorption of thiophene on Ge(100) has been studied using scanning tunneling microscopy (STM), high-resolution core-level photoemission spectroscopy (HRPES), and density functional theory (DFT) calculations. Until now, thiophene is known to react with the Ge(100) dimer through a [4 + 2] cycloaddition reaction at room temperature, similar to the case of thiophene on Si(100). However, we found that thiophene has two adsorption geometries on Ge(100) at room temperature, such as a kinetically favorable Ge-S dative bonding configuration and a thermodynamically stable [4 + 2] cycloaddition adduct. Moreover, our STM results show that under 0.25 ML thiophene molecules preferentially produce one-dimensional molecular chain structures on Ge(100) via the Ge-S dative bonding configuration. 相似文献
106.
T(2) contrast is gaining importance in high field strength MRI. We report a strategy for developing a T(2) contrast agent from paramagnetic metal ions synthesized within an engineered protein cage. The manganese-ferritin nanocomposite showed high T(2) relaxivity indicating its potential as an ultrasensitive T(2) contrast agent. 相似文献
107.
Germanium nanowires (GeNWs) with single, double, quadruple and octuple surface dangling bonds (SDBs) are investigated using density-functional-theory calculations. We show that single SDB defected GeNWs remain semiconducting as their non-defected form while double or multiple SDB defects result in either semiconducting or metallic GeNWs, depending on the defect's locations on the surface. More importantly, we show that the electronic properties of surface defected GeNWs can also be fine-tuned by applying tensile and compressive strains. Upon the right loading, the surface defected GeNWs become half-metallic. In addition, we determine that the surface defected GeNWs can be classified into three classes: (1) GeNWs with zero magnetic moment, which are either metallic or semiconducting; (2) GeNWs with net magnetic moments equal to the number of SDBs, which are semiconducting with distinct spin-up and spin-down configurations; and (3) GeNWs with net magnetic moments significantly lower than the number of SDBs. We also find that only the defected GeNWs that fall under (3) are potentially half-metallic. Our results predict that half-metallic GeNWs can be obtained via engineering of the surface defects and the structures without the presence of impurity dopants. 相似文献
108.
Jung CY Kim JS Kim HS Ha JM Kim ST Lim HJ Koo SM 《Journal of colloid and interface science》2012,367(1):257-263
Monodispersed, submicron-sized Janus ORMOSIL particles with multiple functional groups were prepared by the selective surface reaction of a monolayer film formed at a hexane-water interface. A well-ordered monolayer film was obtained by self-assembly of ORMOSIL particles with multiple functional groups at hexane-water interface. The photopolymerization of an ordered monolayer containing ORMOSIL particles yields a rigid film strong enough to maintain its integrity for transfer and further chemical reaction. The chemical reaction of this ordered film with organic and inorganic functional groups produced Janus ORMOSIL particles with multiple functional groups. The morphologies, structures, and chemical compositions of monolayer films and Janus ORMOSIL particles were characterized by FT-IR, solid state NMR, X-ray diffraction (XRD), optical microscopy (OM), electron microscopies (SEM and TEM), and confocal laser scanning microscopy. 相似文献
109.
110.
Pure separation and sorting of microparticles from complex fluids are essential for biochemical analyses and clinical diagnostics. However, conventional techniques require highly complex and expensive labeling processes for high purity separation. In this study, we present a simple and label-free method for separating microparticles with high purity using the elasto-inertial characteristic of a non-Newtonian fluid in microchannel flow. At the inlet, particle-containing sample flow was pushed toward the side walls by introducing sheath fluid from the center inlet. Particles of 1 μm and 5 μm in diameter, which were suspended in viscoelastic fluid, were successfully separated in the outlet channels: larger particles were notably focused on the centerline of the channel at the outlet, while smaller particles continued flowing along the side walls with minimal lateral migration towards the centerline. The same technique was further applied to separate platelets from diluted whole blood. Through cytometric analysis, we obtained a purity of collected platelets of close to 99.9%. Conclusively, our microparticle separation technique using elasto-inertial forces in non-Newtonian fluid is an effective method for separating and collecting microparticles on the basis of size differences with high purity. 相似文献