全文获取类型
收费全文 | 43547篇 |
免费 | 4170篇 |
国内免费 | 6201篇 |
专业分类
化学 | 15172篇 |
晶体学 | 527篇 |
力学 | 1298篇 |
综合类 | 394篇 |
数学 | 2840篇 |
物理学 | 8431篇 |
综合类 | 25256篇 |
出版年
2024年 | 144篇 |
2023年 | 423篇 |
2022年 | 974篇 |
2021年 | 1072篇 |
2020年 | 973篇 |
2019年 | 1015篇 |
2018年 | 958篇 |
2017年 | 1133篇 |
2016年 | 1336篇 |
2015年 | 1796篇 |
2014年 | 2394篇 |
2013年 | 2852篇 |
2012年 | 3031篇 |
2011年 | 3436篇 |
2010年 | 3162篇 |
2009年 | 3292篇 |
2008年 | 3637篇 |
2007年 | 3376篇 |
2006年 | 3200篇 |
2005年 | 2809篇 |
2004年 | 2194篇 |
2003年 | 1818篇 |
2002年 | 2066篇 |
2001年 | 1825篇 |
2000年 | 1448篇 |
1999年 | 876篇 |
1998年 | 427篇 |
1997年 | 362篇 |
1996年 | 333篇 |
1995年 | 244篇 |
1994年 | 212篇 |
1993年 | 193篇 |
1992年 | 168篇 |
1991年 | 146篇 |
1990年 | 128篇 |
1989年 | 104篇 |
1988年 | 87篇 |
1987年 | 65篇 |
1986年 | 41篇 |
1985年 | 29篇 |
1984年 | 21篇 |
1983年 | 19篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1971年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
11.
12.
13.
新建地方院校实验室仪器设备管理工作探讨 总被引:1,自引:0,他引:1
张勇 《科技情报开发与经济》2007,17(34):231-232
分析了新建地方院校实验室仪器设备管理工作的特点和问题,探讨了加强仪器设备管理的措施。 相似文献
14.
The effect of α‐cyclodextrin (α‐CD) on the crystallization behavior of poly(3‐hydroxybutyrate) (PHB) was investigated with polarized optical microscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. We found that the addition of α‐CD can greatly accelerate the crystallization of PHB and that α‐CD has a potential not only to enhance the nucleation but also to accelerate the crystallization of PHB. Compared to a conventional nucleation agent, such as talc, α‐CD is a natural product and has many advantages because it is environmentally friendly and safe to humans. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3461–3469, 2004 相似文献
15.
Lizeng Wang Chengsong Ma Xiaoli Zhang Yibing Ren Yong Yu 《Fresenius' Journal of Analytical Chemistry》1995,351(7):689-691
The electrochemical behavior of the copper-tyrosine complex has been studied by linear-sweep adsorption voltammetry. In 0.02 mol/L Na2HPO4 buffer solution (pH=9.6), the complex can be adsorped on a hanging mercury drop electrode and reduced at a peak potential of about –0.42 V (vs. SCE). The secondary derivative peak height is linear proportional to the concentration of tyrosine in the range 1.0×10–7–5.0×10–5 mol/L. The detection limit is 5×10–8 mol/L.Project supported by the Provincial Science Foundation of Shandong Province 相似文献
16.
17.
宋继和 《上饶师范学院学报》2002,22(4):30-34
矛盾根本属性原理是我们做好的对外开放工作的指导思想。在对外开放过程中,社会主义中国同国际资本主义双方的矛盾同一性是占据主导地位的,同时也必然存在着矛盾斗争性,但这是第二位的。我们应正确处理对外开放中矛盾同一性与斗争性的关系,着眼于矛盾双方的同一性,使必要的斗争性服务与服从于同一性,以利于对外开放基本国策的实施,加速中国社会主义现代化建设的进程。 相似文献
18.
The interleukin 1β (IL-1β) cDNA was cloned from the red seabream (Pagrus major) by homology cloning strategy. A cDNA fragment was amplified by PCR using two degenerated primers, which were designed according to the conserved regions of other known IL-1β sequences, and elongated by 3' ends and 5' ends RACE PCR to get the full length coding sequence of red seabream IL-1β (RS IL-1β). The sequence contained 1252 nucleotides that included a 5' untranslated region (UTR) of 84bp, a 3' UTR of 410 bp and an open reading frame (ORF) of 759 nucleotides which could be translated into a putative peptide of 253 amino acids with molecular weight of 28.6 kD and putative isoelectric point pI of 5.29. The deduced peptide contained two potential N-glycosylation sites and an identifiable IL1 family signature, but lacked the signal peptide and the clear ICE cut site, which were common in other nonmammalian IL-1β genes. The RS IL-1β had the highest homology with piscine IL-1β according to phylogenetic tree analysis. 相似文献
19.
Yong‐Jin Kim Jin‐Woong Kim Jung‐Eun Lee Jee‐Hyun Ryu Junoh Kim Ih‐Seop Chang Kyung‐Do Suh 《Journal of polymer science. Part A, Polymer chemistry》2004,42(22):5627-5635
Mesoporous polymer microspheres with gold (Au) nanoparticles inside their pores were prepared considering their surface functionality and porosity. The Au/polymer composite microspheres prepared were characterized by transmission electron microscope (TEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) techniques. The results showed that the adsorption of Au nanoparticles could be increased by imparting the pore structure and surface‐functional groups into the supporting polymer microspheres (in this study, poly (ethylene glycol dimethacrylate‐co‐acrylonitrile) and poly (EGDMA‐co‐AN) system). Above all, from this study, it was established that the porosity of the polymer microspheres is the most important factor that determines the distribution and adsorption amount of face‐centered cubic (fcc) Au nanoparticles in the final products. Our study showed that the continuous adsorption of Au nanoparticles with the aid of the large surface area and surface interaction sites formed more favorably the Au/polymer composite microspheres. The BET measurements of Au/poly(EGDMA‐co‐AN) composite microspheres reveals that the adsorption of Au nanoparticles into the pores kept the pore structure intact and made it more porous. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5627–5635, 2004 相似文献
20.