全文获取类型
收费全文 | 4996篇 |
免费 | 150篇 |
国内免费 | 9篇 |
专业分类
化学 | 3672篇 |
晶体学 | 64篇 |
力学 | 52篇 |
综合类 | 2篇 |
数学 | 178篇 |
物理学 | 1187篇 |
出版年
2023年 | 32篇 |
2022年 | 45篇 |
2021年 | 45篇 |
2020年 | 76篇 |
2019年 | 80篇 |
2018年 | 68篇 |
2017年 | 26篇 |
2016年 | 97篇 |
2015年 | 124篇 |
2014年 | 98篇 |
2013年 | 251篇 |
2012年 | 249篇 |
2011年 | 274篇 |
2010年 | 155篇 |
2009年 | 179篇 |
2008年 | 230篇 |
2007年 | 270篇 |
2006年 | 241篇 |
2005年 | 257篇 |
2004年 | 208篇 |
2003年 | 190篇 |
2002年 | 176篇 |
2001年 | 115篇 |
2000年 | 111篇 |
1999年 | 73篇 |
1998年 | 54篇 |
1997年 | 45篇 |
1996年 | 78篇 |
1995年 | 57篇 |
1994年 | 51篇 |
1993年 | 67篇 |
1992年 | 67篇 |
1991年 | 65篇 |
1990年 | 55篇 |
1989年 | 54篇 |
1988年 | 55篇 |
1987年 | 60篇 |
1986年 | 53篇 |
1985年 | 87篇 |
1984年 | 76篇 |
1983年 | 41篇 |
1982年 | 51篇 |
1981年 | 48篇 |
1980年 | 56篇 |
1979年 | 58篇 |
1978年 | 48篇 |
1977年 | 39篇 |
1976年 | 39篇 |
1974年 | 28篇 |
1973年 | 28篇 |
排序方式: 共有5155条查询结果,搜索用时 15 毫秒
21.
22.
23.
Bond IA Budding E Conway MJ Fenton KB Fujii H Fujii Z Fujimoto M Hasegawa H Hayashida N Honda M Hotta N Humble JE Kabe S Kasahara K Kifune T Masaike A Matsubara Y Mitsui K Miura Y Mori M Murakami K Muraki Y Nagano M Nakamura K Nakamura T Norris PM Ohashi Y Okada A Saito T Sakata M Sato H Shibata S Shima M Storey JR Tanimori T Teshima M Torii S Uchino K Watase Y Woodhams MD Yamamoto Y Yock PC Yuda T 《Physical review letters》1988,61(20):2292-2295
24.
25.
Diamond-like carbon films prepared by pulsed-laser evaporation 总被引:1,自引:0,他引:1
T. Sato S. Furuno S. Iguchi M. Hanabusa 《Applied Physics A: Materials Science & Processing》1988,45(4):355-360
Diamond-like carbon thin films were prepared by pulsed-laser evaporation. In this method a carbon target was irradiated by a XeCl laser with a power density of 3×108 W/cm2 and carbon atoms, together with a small number of ions, were produced. Deposition rates and film properties changed sensitively with substrate temperature. The films deposited at 50°C were diamond-like, having reasonable hardness, high refractive index (2.1–2.2 at 633 nm), optical transparency in the infrared, electrical resistivity of 108 cm and chemical inertness (no dissolution in a HFHNO3 solution). The band gap measured from optical absorption was 1.4 eV. Raman spectrum and infrared absorption, whose features varied with the substrate temperature, were also measured. The films were amorphous and no crystallinity was observed, as confirmed by x-ray diffraction, transmission electron diffraction and Raman spectroscopy. Hydrogen atoms were incorporated in the films with a typical H/C ratio of 0.3. The application of a negative bias to the substrate modified the deposition due to the presence of ions. 相似文献
26.
27.
28.
Jin Y Yamanaka J Sato S Miyata I Yomota C Yonese M 《Chemical & pharmaceutical bulletin》2002,50(10):1341-1348
Hyaluronate-hydroxyethyl acrylate blend gel (HA-PHEA) were prepared to modify the brittleness of hyaluronate gel (HA) and the characteristics of HA-PHEA gel were compared with those of HA and polyhydroxyethyl acrylate (PHEA) gels. These gels were high in water content and transparent. HA-PHEA gel was improved in viscoelastic properties due to the elasticity and the high affinity with water of PHEA, and the drying-swelling cycles became reversible. The effective charge densities theta of the gels estimated from membrane potentials were -0.002, -0.008 and 0 mol dm(-3) for HA-PHEA, HA and PHEA gels. Effects of electro- static and nonelectrostatic interactions on absorptions and releases were studied using sodium benzoate (NaBA) as an anionic solute, and methylene blue (MB), chlorpromazine (CPHCl) and benzethonium chloride (BZTCl) as cationic solutes, in which CPHCl and BZTCl are cationic amphiphilic solutes. The releases of MB, CPHCl and BZTCl from HA-PHEA and HA gels were suppressed comparing with those of NaBA. By adding salts, the releases of MB and CPHCl were enhanced but those of BZTCl were suppressed due to enhancement of the intra- and intermicelle formation. In the releases of the cationic solutes from HA-PHEA gel, electrostatic and nonelectrostatic interactions with HA were found to play important roles. Behaviors of the releases from HA-PHEA gel were found to possess the features of HA gel. 相似文献
29.
A stereocontrolled synthesis of 4′-hydroxymethylated ribo--nucleosides and a new psico--nucleoside has been accomplished on the basis of the [3 + 4] reductive cyclocoupling reaction of α,α,α′,α′-tetrabromoacetone and furfuryl acetate. 相似文献
30.
Watanabe G Umetsu K Yuasa I Sato M Sakabe M Naito E Yamanouchi H Suzuki T 《Electrophoresis》2001,22(3):418-420
We present a simple and rapid polymerase chain reaction (PCR)-based technique, termed consumed allele-specific primer analysis (CASPA), as a new strategy for single nucleotide polymorphism (SNP) analysis. The method involves the use of labeled allele-specific primers, differing in length, with several noncomplementary nucleotides added in the 5'-terminal region. After PCR amplification, the amounts of the remaining primers not incorporated into the PCR products are determined. Thus, nucleotide substitutions are identified by measuring the consumption of primers. In this study, the CASPA method was successfully applied to ABO genotyping. In the present method, the allele-specific primer only anneals with the target polymorphic site on the DNA, so it is not necessary to analyze the PCR products. Therefore, this method is only little affected by modification of the PCR products. The CASPA method is expected to be a useful tool for typing of SNPs. 相似文献