全文获取类型
收费全文 | 12396篇 |
免费 | 1096篇 |
国内免费 | 698篇 |
专业分类
化学 | 8364篇 |
晶体学 | 121篇 |
力学 | 492篇 |
综合类 | 51篇 |
数学 | 1484篇 |
物理学 | 3678篇 |
出版年
2023年 | 149篇 |
2022年 | 234篇 |
2021年 | 267篇 |
2020年 | 304篇 |
2019年 | 325篇 |
2018年 | 250篇 |
2017年 | 260篇 |
2016年 | 400篇 |
2015年 | 412篇 |
2014年 | 477篇 |
2013年 | 713篇 |
2012年 | 890篇 |
2011年 | 1025篇 |
2010年 | 651篇 |
2009年 | 676篇 |
2008年 | 769篇 |
2007年 | 734篇 |
2006年 | 647篇 |
2005年 | 561篇 |
2004年 | 532篇 |
2003年 | 455篇 |
2002年 | 404篇 |
2001年 | 330篇 |
2000年 | 270篇 |
1999年 | 206篇 |
1998年 | 162篇 |
1997年 | 139篇 |
1996年 | 175篇 |
1995年 | 131篇 |
1994年 | 150篇 |
1993年 | 124篇 |
1992年 | 117篇 |
1991年 | 96篇 |
1990年 | 106篇 |
1989年 | 82篇 |
1988年 | 90篇 |
1987年 | 61篇 |
1986年 | 69篇 |
1985年 | 95篇 |
1984年 | 69篇 |
1983年 | 68篇 |
1982年 | 49篇 |
1981年 | 46篇 |
1980年 | 47篇 |
1979年 | 34篇 |
1977年 | 37篇 |
1976年 | 37篇 |
1975年 | 34篇 |
1974年 | 48篇 |
1973年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
851.
852.
853.
A plasmonic multilayer structure (PMS) is proposed for photovoltaic cells with an ultrathin active layer that is 30 nm amorphous
Si (α-Si). The optical properties of the PMS are analyzed by rigorous coupled-wave analysis (RCWA) and finite-difference time-domain
(FDTD) method. Using the PMS, the incident light can be trapped into localized surface plasmon (LSP) and then the localized
surface plasmon induces the surface plasmon (SP) that propagates transversely within the α-Si layer. Compared with the indium tin oxide (ITO)/α-Si/Ag structure, the photon number absorbed by PMS increase 28.7% while a normal incident transverse magnetic (TM) polarization
wave is applied. 相似文献
854.
K. Zhou H. P. Wang J. Chang B. Wei 《Applied Physics A: Materials Science & Processing》2011,105(1):211-214
Thermophysical properties of liquid alloys are usually difficult to measure, especially for high melting point and reactive
alloys. In this work, the surface tensions of superheated and undercooled liquid Ti55Al45, Ti50Al45Nb5 and Ti45Al45Nb10 alloys are determined by using oscillating drop method under electromagnetic levitation state. The experimental results of
Ti–Al and Ti–Al–Nb alloys display linear temperature dependence. The maximum undercoolings of 259 (0.143T
L), 268 (0.146T
L) and 275 K (0.147T
L) are respectively achieved for these three alloys. Furthermore, the viscosities of liquid Ti55−x
Al45Nb
x
alloys are also derived from the experimental results. 相似文献
855.
The nonisothermal decomposition kinetics of Ginkgo biloba leaves polyprenol (GBP) and cleaved situation of its chemical bond during thermal decomposition process were first investigated using thermogravimetric (TG) and TG‐FTIR technology. The results of thermal decomposition kinetics revealed that the nonisothermal decomposition mechanism of GBP corresponds to first‐order chemical reaction with n = 1, integral form g(a) = –ln(1 – a) and differential form f(a) = 1 – a. TG‐FTIR results demonstrated that absorbance of –CH3, unsaturated C–H bond, =CH2, accumulated C=C, –OH, and so on constantly increased with thermal decomposition reaction went on. In addition, storage life of GBP was also evaluated. These data could provide theoretical guidance for purification under high temperature and other thermal application of GBP. 相似文献
856.
S. P. Changlai H. H. Tsai S. C. Tsai H. P. Chen C. L. Chang Y. H. Yao C. Y. Chen 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):859-863
This work is the first evaluation of environmental gamma exposure rates by the Nuclear Medicine Department at Lin Shin Hospital
(LSH) in Taichung with Thermoluminescent dosimeter (TLD-100H) during the Fukushima Nuclear Power Plant (FNPP) accident. After
the 9.0 MW strong earthquake hit northern Japan on March 11, 2011, a TLD-100H was used to monitor environmental kerma rate at Taichung
(2,500 km away from northern Japan) from Mar-08 to Apr-09, 2011 and evaluated kerma rate due to global fallout of the sever
FNPP accidents. Exposure rates varied widely among positions close to the PET/CT facility. Observed kerma rates of up to 4.12 ± 0.62 mSv mo−1 indicated an explicit, heavy leakage of photon through the PET/CT facility. No significant contributions were detected at
Taichung, Taiwan. Hence, the health effect cause by the “extra radiation” from FNPP accidents is negligible. As this was a
rare case of environmental monitoring during a nuclear power plant accident, its findings are of considerable significance. 相似文献
857.
858.
859.
Chang Naon Eun Heechul Won Huijun Kim Seonbyeong Seo Bumkyung Kim Yongsoo 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(3):1045-1051
Journal of Radioanalytical and Nuclear Chemistry - Polypropylene (PP) filters are used for the treatment of radioactive liquid waste containing gamma nuclides such as Co-60, and filter physical and... 相似文献
860.