全文获取类型
收费全文 | 17132篇 |
免费 | 395篇 |
国内免费 | 114篇 |
专业分类
化学 | 11549篇 |
晶体学 | 293篇 |
力学 | 477篇 |
综合类 | 1篇 |
数学 | 2510篇 |
物理学 | 2811篇 |
出版年
2022年 | 114篇 |
2021年 | 135篇 |
2020年 | 165篇 |
2019年 | 163篇 |
2018年 | 138篇 |
2017年 | 121篇 |
2016年 | 314篇 |
2015年 | 284篇 |
2014年 | 275篇 |
2013年 | 831篇 |
2012年 | 748篇 |
2011年 | 856篇 |
2010年 | 455篇 |
2009年 | 392篇 |
2008年 | 785篇 |
2007年 | 829篇 |
2006年 | 821篇 |
2005年 | 766篇 |
2004年 | 667篇 |
2003年 | 554篇 |
2002年 | 632篇 |
2001年 | 252篇 |
2000年 | 250篇 |
1999年 | 212篇 |
1998年 | 204篇 |
1997年 | 278篇 |
1996年 | 316篇 |
1995年 | 218篇 |
1994年 | 227篇 |
1993年 | 255篇 |
1992年 | 240篇 |
1991年 | 177篇 |
1990年 | 194篇 |
1989年 | 206篇 |
1988年 | 196篇 |
1987年 | 167篇 |
1986年 | 176篇 |
1985年 | 268篇 |
1984年 | 288篇 |
1983年 | 213篇 |
1982年 | 300篇 |
1981年 | 266篇 |
1980年 | 231篇 |
1979年 | 224篇 |
1978年 | 213篇 |
1977年 | 201篇 |
1976年 | 197篇 |
1975年 | 203篇 |
1974年 | 218篇 |
1973年 | 185篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
William H. Bearden Valorie M. Cargin Willie R. Roberson 《Magnetic resonance in chemistry : MRC》1981,15(2):131-132
While there is a useable paramagnetic relaxation reagent (PARR) for use in nonpolar or low polarity solvents, there has not been a practical PARR for use in highly polar solvents. A reagent, Gd(NO3)3-inositol, is described which appears to satisfy this need. The performance of the reagent is given in terms of its effect on the T1, NOE and line width values of N,N-dimethylformamide. In addition, the application of this reagent to adenosine is also reported. 相似文献
992.
We point out an error in the proof of Nishijima et al. that the Bethe-Salpeter wave function for composite particles, lying on Regge trajectories, is finite. We describe a simple counter-example drawn from non-relativistic quantum mechanics and cite others from field theory. 相似文献
993.
994.
995.
996.
A noise survey has been undertaken on over 1000 vehicles operating on public roads. By the use of a remote device, vehicle velocity and acceleration have been measured and related to the instantaneous sound pressure level emission from the vehicle. The relationship is expressed in terms of A-weighted sound pressure level as a function of both velocity and acceleration. Octave band sound pressure levels are also expressed as functions of these variables. Light and heavy vehicle groups are considered separately. 相似文献
997.
998.
999.
Evolution of porosity in geotechnical composites 总被引:4,自引:0,他引:4
Nuclear magnetic resonance (NMR) (H1) transverse relaxation measurements were carried out on 37x70-mm cylindrical mineral/organic composites to determine and monitor the porosity evolution. Porosity is related, in principle, to the stability of such materials in geotechnical applications, for example, engineering foundations. The specimens represented novel formulations of mixed "wastes" containing coarse screened mineral, digested sewage sludge, quicklime, and pulverized fuel ash mixed and compacted together to form mechanically competent material. The measurements on a selected formulation indicated initially low porosity (<12%) that becomes lower over 6 months ( approximately 8%) due to pozzolanic reactions occurring. A relaxation time cutoff of 1.5 ms between "bound" and 'mobile' pore water much lower than sandstones (33 ms) was observed. The results confirmed that the NMR method allows a more reliable assessment of porosity and pore-size evolution. 相似文献
1000.
BACKGROUND: Human papillomaviruses (HPV) are the most common sexually transmitted viruses. Infection of the cervical epithelium by HPVs can lead to the development of cervical cancer. Recent advances in vaccine research have shown that immunization with papillomavirus-like particles (VLPs) containing the major structural viral protein, L1 from HPV 16 can provide protection from the establishment of a chronic HPV 16 infection and related cervical intraepithelial neoplasia (CIN) in baseline HPV 16 naive women. METHODS: To better understand the quantitative and qualitative effects of aluminum adjuvant on the immunogenic properties of an HPV 6, 11, 16 and 18L1 VLP vaccine, we used an HPV-specific, antibody isotyping assay and a competitive immunoassay that measures antibodies to neutralizing epitopes to profile sera from rhesus macaques immunized with the HPV L1 VLP vaccine formulated with or without aluminum adjuvant. RESULTS: Immunization with VLPs formulated with the aluminum adjuvant elicited a significantly stronger immune response with higher peak antibody titers both at four weeks post vaccination (12.7 to 41.9-fold higher) as well as in the persistent phase at week 52 (4.3 to 26.7-fold higher) than that of VLPs alone. Furthermore, the aluminum adjuvant formulated HPV VLP vaccine elicited a predominantly T helper type 2 response, with high levels of IgG1 and IgG4 and low levels of IgG2. The vaccine also elicited high levels of serum IgA, which may be important in providing mucosal immunity to impart protection in the anogenital tract. CONCLUSION: These results show that the HPV 6, 11, 16 and 18 L1-VLP vaccine formulated with Merck aluminum adjuvant elicits a robust and durable immune response and holds promise as a vaccine for preventing cervical cancer. 相似文献