全文获取类型
收费全文 | 16379篇 |
免费 | 1566篇 |
国内免费 | 1044篇 |
专业分类
化学 | 10734篇 |
晶体学 | 176篇 |
力学 | 630篇 |
综合类 | 110篇 |
数学 | 2385篇 |
物理学 | 4954篇 |
出版年
2023年 | 212篇 |
2022年 | 331篇 |
2021年 | 375篇 |
2020年 | 428篇 |
2019年 | 429篇 |
2018年 | 387篇 |
2017年 | 433篇 |
2016年 | 698篇 |
2015年 | 617篇 |
2014年 | 780篇 |
2013年 | 1181篇 |
2012年 | 1229篇 |
2011年 | 1293篇 |
2010年 | 880篇 |
2009年 | 757篇 |
2008年 | 893篇 |
2007年 | 778篇 |
2006年 | 657篇 |
2005年 | 517篇 |
2004年 | 512篇 |
2003年 | 457篇 |
2002年 | 470篇 |
2001年 | 375篇 |
2000年 | 277篇 |
1999年 | 286篇 |
1998年 | 205篇 |
1997年 | 163篇 |
1996年 | 179篇 |
1995年 | 162篇 |
1994年 | 165篇 |
1993年 | 137篇 |
1992年 | 137篇 |
1991年 | 121篇 |
1990年 | 104篇 |
1989年 | 122篇 |
1988年 | 91篇 |
1987年 | 87篇 |
1986年 | 99篇 |
1985年 | 118篇 |
1984年 | 97篇 |
1983年 | 84篇 |
1982年 | 80篇 |
1980年 | 61篇 |
1979年 | 66篇 |
1978年 | 83篇 |
1977年 | 64篇 |
1976年 | 84篇 |
1975年 | 65篇 |
1974年 | 69篇 |
1968年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
用射频磁控溅射法在80℃衬底温度下制备出MgxZn1-xO(x=0.16)薄膜,用X射线衍射(XRD)、光致发光(PL)和透射谱研究了退火温度对MgxZn1-xO薄膜结构和光学性质的影响.测量结果显示,MgxZn1-xO薄膜为单相六角纤锌矿结构,并且具有沿c轴的择优取向;随着退火温度的升高,(002)XRD峰强度、平均晶粒尺寸和紫外PL峰强度增大,(002)XRD峰半高宽(F
关键词:
xZn1-xO薄膜')" href="#">MgxZn1-xO薄膜
射频磁控溅射
退火 相似文献
62.
Kyung Hwa Hong Jong Lyoul Park In Hwan Sul Ji Ho Youk Tae Jin Kang 《Journal of Polymer Science.Polymer Physics》2006,44(17):2468-2474
Polyvinyl alcohol (PVA) nanofibers containing Ag nanoparticles were prepared by electrospinning PVA/silver nitrate (AgNO3) aqueous solutions, followed by short heat treatment, and their antimicrobial activity was investigated for wound dressing applications. Since PVA is a water soluble and biocompatible polymer, it is one of the best materials for the preparation of wound dressing nanofibers. After heat treatment at 155 °C for 3 min, the PVA/AgNO3 nanofibers became insoluble, while the Ag+ ions therein were reduced so as to produce a large number of Ag nanoparticles situated preferentially on their surface. The residual Ag+ ions were reduced by subsequent UV irradiation for 3 h. The average diameter of the Ag nanoparticles after the heat treatment was 5.9 nm and this value increased slightly to 6.3 nm after UV irradiation. It was found that most of the Ag+ ions were reduced by the simple heat treatment. The PVA nanofibers containing Ag nanoparticles showed very strong antimicrobial activity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2468–2474, 2006 相似文献
63.
Hà Huy Tài 《manuscripta mathematica》2002,107(4):479-501
Suppose ? is a set of arbitrary number of smooth points in ℙ2
its defining ideal. In this paper, we study the Rees algebras of the ideals generated by I
t
, t ≥α. When the points of ? are general, we give a set of defining equations for the Rees algebra . When the points of ? are arbitrary, we show that for all t≫ 0, the Rees algebra is Cohen-Macaulay and its defining ideal is generated by quadratics. A cohomological characterization for arithmetic Cohen-Macaulayness
of subvarieties of a product space is also given.
Received 4 April 2001 相似文献
64.
Jiří Rais 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(3):709-710
Dr. Miroslav Kyrš, DrSc. passed away prematurely and unexpectedly in August 2006 at age of 75. He was a leading person of
the Czech radiochemistry during the second half of the 20th century and his results have of world-wide impact. His diligence,
intelligence and permanent activity led him to be at first a laboratory chief and subsequently for about 25 years to be a
chief of the Radiochemical Department of Czech Nuclear Research Institute (NRI) at Řež near Prague. 相似文献
65.
We prove that a for a mapping f of finite distortion , the -Hausdorff measure of any point preimage is zero provided is integrable, with , and the multiplicity function of f is essentially bounded. As a consequence for we obtain that the mapping is then open and discrete.
Received: 18 June 2001 / Revised version: 31 January 2002 / Published online: 27 June 2002 相似文献
66.
The IR finite one-loop box scalar integral with massless internal lines has been recalculated. The result is very compact,
simple and valid for arbitrary values of the relevant kinematic variables. It is given in terms of only two dilogarithms and
a few logarithms, all of very simple arguments.
Received: 31 January 2002 / Published online: 26 April 2002 相似文献
67.
68.
采用矩阵奇异值分解(singular value decomposition, SVD)的方法,对高温射频超导量子干涉仪(HTc rf-SQUID)采集到的单通道心磁信号进行处理.证明了对于近似周期性的心磁信号,在无参考噪声的情况下矩阵奇异值分解的方法与自适应窄带陷波相结合有较好的消除广谱噪声的效果.
关键词:
高温射频超导量子干涉仪
心磁信号
奇异值分解
噪声消除 相似文献
69.
几种陆用惯性自寻北方案的比较 总被引:2,自引:1,他引:1
介绍几种目前广泛应用于军事及民用工业领域的高精度自寻北方案,同时讨论并分析了这些方案的精度和误差补偿方法,提出在兵器领域尤其是在陆用车辆上的适用性等问题。 相似文献
70.