全文获取类型
收费全文 | 7172篇 |
免费 | 1189篇 |
国内免费 | 754篇 |
专业分类
化学 | 4871篇 |
晶体学 | 74篇 |
力学 | 421篇 |
综合类 | 44篇 |
数学 | 672篇 |
物理学 | 3033篇 |
出版年
2024年 | 18篇 |
2023年 | 169篇 |
2022年 | 175篇 |
2021年 | 191篇 |
2020年 | 286篇 |
2019年 | 255篇 |
2018年 | 221篇 |
2017年 | 205篇 |
2016年 | 315篇 |
2015年 | 309篇 |
2014年 | 372篇 |
2013年 | 517篇 |
2012年 | 570篇 |
2011年 | 619篇 |
2010年 | 420篇 |
2009年 | 419篇 |
2008年 | 443篇 |
2007年 | 365篇 |
2006年 | 358篇 |
2005年 | 333篇 |
2004年 | 276篇 |
2003年 | 203篇 |
2002年 | 222篇 |
2001年 | 176篇 |
2000年 | 168篇 |
1999年 | 175篇 |
1998年 | 129篇 |
1997年 | 128篇 |
1996年 | 151篇 |
1995年 | 107篇 |
1994年 | 114篇 |
1993年 | 108篇 |
1992年 | 100篇 |
1991年 | 82篇 |
1990年 | 64篇 |
1989年 | 74篇 |
1988年 | 52篇 |
1987年 | 46篇 |
1986年 | 38篇 |
1985年 | 34篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有9115条查询结果,搜索用时 46 毫秒
151.
152.
Weaver M Arisaka K Roberts D Slater W Briere RA Cheu E Harris DA Roodman A Schwingenheuer B Wah YW Winstein B Winston R Barker AR Swallow EC Bock GJ Coleman R Crisler M Enagonia J Ford R Hsiung YB Jensen DA McFarland KS Ramberg E Tschirhart R Collins EM Gollin GD Nakaya T Yamanaka T Gu P Haas P Hogan WP Kim SK Matthews JN Myung SS Schnetzer S Somalwar SV Thomson GB Zou Y 《Physical review letters》1994,72(24):3758-3761
153.
154.
155.
Gu P Haas P Hogan WP Kim SK Matthews JN Myung SS Schnetzer S Thomson GB Zou Y Arisaka K Roberts D Slater W Spencer MB Weaver M Briere RA Cheu E Harris DA Krolak P McFarland KS Roodman A Schwingenheuer B Somalwar SV Wah YW Winstein B Winston R Barker AR Swallow EC Bock GJ Coleman R Crisler M Enagonio J Ford R Hsiung YB Jensen DA O'Dell VR Ramberg E Tschirhart R Collins EM Gollin GD Nakaya T Yamanaka T 《Physical review letters》1996,76(23):4312-4315
156.
The use of dilute acid for mercury extraction from geological samples with microwave assisted heating was investigated. An orthogonal array design OA(16)(4(1)x2(12)) was applied to select the optimum conditions. The effects of the concentration of HNO(3), the additions of HCl and H(2)S0(4), the extraction time and their interactions were evaluated by the mixed-level orthogonal array design (OAD). The results indicated that the addition of small amount of HCl would improve significantly the extraction of mercury from soil matrices. From the study, it is seen that the mercury in the soil matrices could be extracted completely by 14% (v/v) HNO(3) with small quantity of HCl. The effects of the pressure within the digestion vessel and the sample mass were studied under the optimum conditions derived from the OAD. The extraction methods with optimum conditions were evaluated by determining mercury in NIST SRM 1645 River Sediment, NIES CRM No. 2 Pond Sediment and NRCC BCSS-1 Marine Sediment. Recoveries of 78-109% were achieved. Good mean recoveries of 95-98% were also obtained from real soil samples spiked with different species of mercury. 相似文献
157.
158.
We investigate classical electronic collisions with a He(+) ion. Scattering functions, such as the scattering angle, collisional time, or energy of the outgoing electron, all exhibit an interesting hierarchial self-similar structure, which can be interpreted in terms of the indefinite number of electronic returns to the vicinity of the nucleus, encounters between electrons, and Keplerian excursions of electrons during the collisional processes. Based on this mechanism a binary coding is introduced to organize the dynamics of this three-body system and to provide an understanding of the self-similarity among generations of scale magnification, which yields escape rates that vary with the sectional cut into the parameter space. The self-similarity displayed within a single generation, on the other hand, can be simply tied to the periods of the two independent electronic excursions. The physical interpretation and the symbolic dynamics introduced here are generally useful for three-body collisional systems, including atomic, molecular, or stellar collisions. 相似文献
159.
160.