全文获取类型
收费全文 | 3315篇 |
免费 | 179篇 |
国内免费 | 8篇 |
专业分类
化学 | 2624篇 |
晶体学 | 32篇 |
力学 | 49篇 |
数学 | 232篇 |
物理学 | 565篇 |
出版年
2023年 | 17篇 |
2022年 | 68篇 |
2021年 | 94篇 |
2020年 | 76篇 |
2019年 | 79篇 |
2018年 | 62篇 |
2017年 | 65篇 |
2016年 | 108篇 |
2015年 | 134篇 |
2014年 | 129篇 |
2013年 | 219篇 |
2012年 | 294篇 |
2011年 | 306篇 |
2010年 | 175篇 |
2009年 | 142篇 |
2008年 | 228篇 |
2007年 | 189篇 |
2006年 | 172篇 |
2005年 | 161篇 |
2004年 | 133篇 |
2003年 | 109篇 |
2002年 | 106篇 |
2001年 | 61篇 |
2000年 | 40篇 |
1999年 | 40篇 |
1998年 | 27篇 |
1997年 | 23篇 |
1996年 | 24篇 |
1995年 | 16篇 |
1994年 | 22篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有3502条查询结果,搜索用时 15 毫秒
11.
Chi Kin Chau Kwang Mong Sim 《Operations Research Letters》2003,31(5):327-334
By showing that there is an upper bound for the price of anarchyρ(Γ) for a non-atomic congestion game Γ with only separable cost maps and fixed demands, Roughgarden and Tardos show that the cost of forgoing centralized control is mild. This letter shows that there is an upper bound for ρ(Γ) in Γ for fixed demands with symmetric cost maps. It also shows that there is a weaker bound for ρ(Γ) in Γ with elastic demands. 相似文献
12.
Jien Wu Xiao-Fang Cheng Leslie J. Harrison Swee-Hock Goh Keng-Yeow Sim 《Tetrahedron letters》2004,45(52):9657-9659
Examination of the aerial parts of a Chinese herbal medicine yielded a novel metabolite, perforatumone 1, which is characterized by its unique carbon skeleton. Its structure was determined by detailed spectroscopic analysis. 相似文献
13.
Do Young Kim Ji Sim Jung Young Rae Jang Kun Ho Yoo Jin Jang 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):400
We studied the growth of nanocrystalline silicon (nc-Si) thin film exhibiting a strong room temperature photoluminescence (PL) at 1.81–2.003 eV. The amorphous silicon was crystallized by Ni silicide mediated crystallization (Ni SMC) and then Secco-etched to exhibit the PL. The PL peak energy and intensity increase with increasing the metal density on the a-Si because of the reduction in the grain size down to 2 nm. The photoluminescence energy and peak intensity depend strongly on the Secco etch time because the grain size is reduced by etching the grain boundaries. 相似文献
14.
The facility layout problem is concerned with finding the most efficient arrangement of a given number of departments with unequal area requirements within a facility. The facility layout problem is a hard problem, and therefore, exact solution methods are only feasible for small or greatly restricted problems. In this paper, we propose a spring-embedding approach that unlike previous approaches results in a model that is convex. Numerical results demonstrating the potential of our model and the efficiency of our solution procedure are presented. 相似文献
15.
Theoretical concerns about the use of cemented and press-fit stems in revision total knee arthroplasty (TKA) include stress
shielding with adverse effects on prosthesis fixation. Radiological studies have showed distal femoral bone resorption after
revision TKA. The revision with use of stems can place abnormal stresses. These stresses can promote the effect of bone stress
shielding and may contribute to bone loss. Experimental quantification of strain shielding in the distal synthetic femur following
TKA is the main purpose of the present study. Three different constructs of TKA were assessed. The first construct included
a stemless femoral component. The other two included a press-fit and a cemented femoral stem. Cortical bone strains were measured
experimentally with tri-axial strain gauges in synthetic femurs before and after in-vitro knee surgery. The difference between
principal strains of implanted and intact femur was calculated for each strain gauge position. This study indicates that the
use of stems in distal femur changes the distribution and magnitude of bone strains. The press-fit stem provoked relevant
bone area (stem length) subjected to strain shielding and also originated the highest reduction of strains in the distal region,
which can potentially induce bone resorption. The stemless implanted femur produced minor bone strain changes relatively to
the intact femur. The use of distal femur stems increases initial stability in the bone, but the observed reduction of strains
in this region, relative to the intact femur, provokes strain shielding that can induce bone resorption and may compromise
the long term implant stability. 相似文献
16.
17.
18.
Cascade Grating Structure for Increasing the Channel Number on Holographic Demultiplexer 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jun Won AN 《中国物理快报》2006,23(6):1459-1461
The expansion capability of the channel number in the optical demultiplexer using two cascaded photopolymer volume gratings is reported. It could be accomplished by designing of two gratings with different spectral range. As a result of the experiment, a 0.4-nm-spaced 130-channel demultiplexer with the channel uniformity of 3.5 dB, the 3 riB-bandwidth of 0.12nm, and the channel crosstalk of-20 dB is experimentally demonstrated. 相似文献
19.
20.