全文获取类型
收费全文 | 2790篇 |
免费 | 117篇 |
国内免费 | 9篇 |
专业分类
化学 | 2152篇 |
晶体学 | 33篇 |
力学 | 75篇 |
数学 | 136篇 |
物理学 | 520篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 52篇 |
2021年 | 54篇 |
2020年 | 56篇 |
2019年 | 49篇 |
2018年 | 37篇 |
2017年 | 32篇 |
2016年 | 91篇 |
2015年 | 81篇 |
2014年 | 88篇 |
2013年 | 156篇 |
2012年 | 218篇 |
2011年 | 248篇 |
2010年 | 161篇 |
2009年 | 133篇 |
2008年 | 218篇 |
2007年 | 194篇 |
2006年 | 170篇 |
2005年 | 167篇 |
2004年 | 112篇 |
2003年 | 93篇 |
2002年 | 99篇 |
2001年 | 57篇 |
2000年 | 42篇 |
1999年 | 49篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 28篇 |
1995年 | 26篇 |
1994年 | 22篇 |
1993年 | 23篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有2916条查询结果,搜索用时 15 毫秒
71.
Saeromi Chung Mahmood H. Akhtar A. Benboudiaf Deog‐Su Park Yoon‐Bo Shim 《Electroanalysis》2020,32(3):520-527
An electrochemical sensor based on the conducting polymer composite with a palladium complex (Pd(C2H4N2S2)2) was developed for the detection of serotonin and dopamine simultaneously in the breast cancer cell and human plasma samples. The proposed sensor was fabricated using the Pd(C2H4N2S2)2 complex‐anchored poly2,2 : 5,2‐terthiophene‐3‐(p‐benzoic acid) (pTBA) layer on the AuNPs decorated reduced graphene oxide (AuNPs@rGO) substrate, which revealed the enhanced anodic current of the target species. The sensor probe was characterized by electrochemical and surface analysis methods. The experimental parameters affecting the sensor performance were optimized, in terms of AuNPs@rGO concentration, the number of electropolymerization cycle for pTBA, immobilization time of Pd(C2H4N2S2)2, and pH. The dynamic ranges for serotonin and dopamine were obtained from 0.02 to 200 μM, and from 0.1 to 200 μM with the detection limit of 2.5, and 24.0 nM, respectively. The reliability of proposed sensor was evaluated using cancer cell lines for the clinical applications. 相似文献
72.
Deok-Heon Kweon Su-Dong Cho Sung-Kyu Kirn Joo-Wha Chung Yong-Jin Yoon 《Journal of heterocyclic chemistry》1996,33(6):1915-1918
3,4,5-Trichloropyridazin-6-one, 3,4,5,6-tetrachloropyridzine and 4,5-dichloro-3-(N,N-dimethylamino)-pyridazin-6-one were synthesized from 4,5-dichloro-3-nitropyridazin-6-one and dimethylchloromethylene-ammonium chloride selectively. 相似文献
73.
A Fluorescent Sensor for Dual‐Channel Discrimination between Phosgene and a Nerve‐Gas Mimic 下载免费PDF全文
Dr. Xin Zhou Yiying Zeng Chen Liyan Prof. Xue Wu Prof. Juyoung Yoon 《Angewandte Chemie (International ed. in English)》2016,55(15):4729-4733
The ability to analyze highly toxic chemical warfare agents (CWAs) and related chemicals in a rapid and precise manner is essential in order to alleviate serious threats to humankind and public security caused by unexpected terrorist attacks and industrial accidents. In this investigation, we designed a o‐phenylenediamine‐pyronin linked dye that is capable of both fluorogenic and colorimetric discrimination between phosgene and the prototypical nerve‐agent mimic, diethyl chlorophosphate (DCP) in the solution or gas phase. Moreover, this dye has been used to construct a portable kit that can be employed for real‐time monitoring of DCP and phosgene in the field, both in a discriminatory manner, and in a simple and safe way. 相似文献
74.
Young-Gui Yoon Bernd G. Pfrommer Steven G. Louie Andrew Canning 《Solid State Communications》2004,131(1):15-19
We present calculations of NMR chemical shifts in crystalline phases of some representative amino acids such as glycine, alanine, and alanyl-alanine. We explore the effects of environment on the chemical shifts in selected glycine geometries ranging from the crystalline phase to completely isolated molecules. In the crystalline and dilute molecular limits, the calculated distinct NMR chemical shifts are attributed to intermolecular hydrogen-bonds and dipole electric field effects, respectively. 相似文献
75.
A one-dimensional system of Si(111)-(5 x 2)-Au is explored using scanning tunneling microscopy and spectroscopy. The chain of Si adatoms called bright protrusions (BP's) is found to be semiconducting with an evanescent state in the gap, which originates from adjoining metallic BP-free segments. A quantitative analysis shows that the evanescent state decays in inverse-Gaussian form, leading to an appearance of a parabolic BP chain, and scales to its chain length. Spatial decay of the state suggests a quadratic band bending and the existence of a Schottky-like potential barrier at the interface driven by charge transfer. 相似文献
76.
Seong Yong Yoon Hoo San LeeSok Hyun Kong Hoon Sang Oh 《Journal of magnetism and magnetic materials》2007
We studied the magnetic and noise properties with various soft underlayer (SUL) types. For an as-deposited SUL, the results of spectrum, oscilloscope waveform and MFM indicated that the SUL types with IrMn pinning layer have more noise level than that of SUL types without IrMn pinning layer. And, after magnetic filed annealing along radial direction of disk, the exchange bias field increased and the noise level of type B (exchange bias type) decreased. These results reveal that incomplete or partial coupling may be generated at the interface between IrMn and ferromagnetic layer in as-deposited SUL. This incomplete coupling may result in complex or multidomain patterns in ferromagnetic layer. 相似文献
77.
We show that the phase transition from the decelerating universe to the accelerating universe, which is of relevance to the cosmological coincidence problem, is possible in the semiclassically quantized two-dimensional dilaton gravity by taking into account the noncommutative field variables during the finite time. Initially, the quantum-mechanically induced energy from the noncommutativity among the fields makes the early universe decelerate and subsequently the universe is accelerating because the dilaton driven cosmology becomes dominant later. 相似文献
78.
Lee JS Kim YY Kim JS Kang YJ 《The Journal of the Acoustical Society of America》2008,123(4):2094-2106
Optimal shape design of a two-dimensional poroelastic acoustical foam is formulated as a topology optimization problem. For a poroelastic acoustical system consisting of an air region and a poroelastic foam region, two different physical regions are continuously changed in an iterative design process. To automatically account for the moving interfaces between two regions, we propose a new unified model to analyze the whole poroelastic acoustical foam system with one set of governing equations; Biot's equations are modified with a material property interpolation from a topology optimization method. With the unified analysis model, we carry out two-dimensional optimal shape design of a poroelastic acoustical foam by a gradient-based topology optimization setting. The specific objective is the maximization of the absorption coefficient in low and middle ranges of frequencies with different amounts of a poroelastic material. The performances of the obtained shapes are compared with those of well-known wedge shapes, and the improvement of absorption is physically interpreted. 相似文献
79.
Sunyoung Kim Dan-Bi Kim Wenjie Jin Junghyuck Park Wonjin Yoon Yunyeol Lee 《Natural product research》2018,32(10):1193-1197
We evaluated organosulphur compounds in Allium vegetables, including garlic, elephant garlic and onion, using high-performance liquid chromatography. Among organosulphur compounds, elephant garlic had considerable γ-glutamyl peptides, and garlic had the highest alliin content. Onion had low level of organosulphur compounds than did elephant garlic and garlic. In addition, antioxidant capacities were evaluated by oxygen radical absorbance capacity (ORAC) values and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay. The results showed that garlic had the highest antioxidant capacity, followed by elephant garlic and onion. Furthermore, a positive correlation was observed between antioxidant activities and organosulphur compounds (R > 0.77). Therefore, our results indicate that there was a close relationship between antioxidant capacity and organosulphur compounds in Allium vegetables. 相似文献
80.
Dr. Sanil E. Sivan Minhui Lee Su-Kyung Lee Dr. Ji Woong Yoon Dr. Kiwoong Kim Dr. Do-Young Hong Kyung-Ho Cho Dr. U-Hwang Lee Prof. Jong-San Chang Dr. Jaehoon Jung Prof. Young Kyu Hwang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(56):12889-12894
Oxo-bridged trimeric chromium acetate clusters [Cr3O(OOCCH3)6(H2O)3]NO3 have been encapsulated for the first time in the mesoporous cages of the chromium terephthalate MIL-101(Cr). The isolated clusters in MIL-101(Cr) have increased affinity towards propylene compared to propane, due to generation of a new kind of pocket-based propylene-binding site, as supported by DFT calculations. 相似文献