全文获取类型
收费全文 | 26812篇 |
免费 | 4700篇 |
国内免费 | 8182篇 |
专业分类
化学 | 19886篇 |
晶体学 | 987篇 |
力学 | 1818篇 |
综合类 | 776篇 |
数学 | 3612篇 |
物理学 | 12615篇 |
出版年
2024年 | 64篇 |
2023年 | 243篇 |
2022年 | 837篇 |
2021年 | 841篇 |
2020年 | 894篇 |
2019年 | 935篇 |
2018年 | 807篇 |
2017年 | 1098篇 |
2016年 | 1039篇 |
2015年 | 1380篇 |
2014年 | 1665篇 |
2013年 | 2111篇 |
2012年 | 2145篇 |
2011年 | 2424篇 |
2010年 | 2368篇 |
2009年 | 2401篇 |
2008年 | 2634篇 |
2007年 | 2357篇 |
2006年 | 2336篇 |
2005年 | 1939篇 |
2004年 | 1505篇 |
2003年 | 1210篇 |
2002年 | 1099篇 |
2001年 | 1074篇 |
2000年 | 1024篇 |
1999年 | 592篇 |
1998年 | 378篇 |
1997年 | 279篇 |
1996年 | 267篇 |
1995年 | 222篇 |
1994年 | 217篇 |
1993年 | 201篇 |
1992年 | 226篇 |
1991年 | 112篇 |
1990年 | 127篇 |
1989年 | 93篇 |
1988年 | 109篇 |
1987年 | 81篇 |
1986年 | 62篇 |
1985年 | 55篇 |
1984年 | 43篇 |
1983年 | 56篇 |
1982年 | 23篇 |
1981年 | 26篇 |
1980年 | 12篇 |
1979年 | 30篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1971年 | 5篇 |
1959年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
What Is Its Real Existing Form?——Theoretical and Experimental Studies on 2-Mercaptobenzothiazole 总被引:1,自引:0,他引:1
1 INTRODUCTION The study of heterocyclic molecules with aroma- tic rings and their absorptions on metals is of con- siderable importance from both theoretical and te- chnological points of view. These molecules are in- teresting because of their applications as corrosion inhibitors and flotation collectors, and their abilities to form self-assembly layers[1]. 2-Mercaptobenzo- thiazole (C7H5NS2, in the following MBT) is an important heterocyclic molecule, which can be used as corrosion … 相似文献
6.
与HBV X蛋白相互作用的细胞蛋白的筛选及其鉴定 总被引:1,自引:1,他引:0
参考GenBank核苷酸序列库中的HBV的核苷酸序列设计合成了一对对应于HBx基因的引物,从原发性肝癌(hepatocellular carcinoma,HCC)患者的血清中提取HBV基因组DNA作为模板,扩增HBx编码区并测定了核苷酸序列.将该编码区克隆到酵母双杂交系统的诱饵蛋白表达载体pGBKT7中,转入酵母细胞AH109,进行表型鉴定.然后通过Mating实验从已制备好用于酵母双杂交系统的肝cDNA表达文库中筛选与HBx相互作用的细胞蛋白,并用体外免疫共沉淀实验进一步验证.研究表明,分离得到的与HBx基因编码的蛋白相互作用的4种新的细胞蛋白,分别是醛缩酶B、C8α亚基、一种丝氨酸蛋白酶Hepsin和一种未知蛋白. 相似文献
7.
A new electroactive polynuclear inorganic compound of rare earth metal, gadolinium hexacyanoferrate (GdHCF), was prepared and characterized using the techniques of FTIR spectroscopy, thermogravimetric analysis (TG), UV-Vis spectrometry, X-ray photoelectron spectroscopy (XPS), ICP atomic emission spectroscopy, and EDX. The results of ICP atomic emission spectroscopy, EDX, and TGA indicated that the prepared GdHCF sample had a stoichiometry of NaGdFe(CN)6·12H2O (when GdHCF was prepared in NaCl solution). The FTIR spectrum of GdHCF showed that there were two types of water molecules in the structure of GdHCF: one was the interstitial water (5 H2O), which resulted from the association of water due to H-bonding, and the other was water coordinated with Gd (7 H2O). The results obtained using XPS showed that the oxidation state of Fe and Gd in the GdHCF sample was +2 and +3, respectively. GdHCF was immobilized on the surface of spectroscopically pure graphite (SG) electrode forming the GdHCF/SG electrode, and the solid-state electrochemistry of the resultant electrode was studied using cyclic voltammetry. The cyclic voltammetric results indicated that the GdHCF/SG electrode exhibited a pair of well-defined and stable redox peaks with the formal potential of E0′=(197±3) mV. The effects of the concentration of the supporting electrolyte on the electrochemical characteristics of GdHCF were studied, and the results showed that the value of E0′ increased linearly with the activity of the cationic ion of the supporting electrolyte (lgaNa+), with a slope of 54.1 mV, which may become a novel method for determining the activity of Na+ in solution. Further experimental results indicated that GdHCF had electrocatalytic activities toward the oxidation of dopamine (DA) and ascorbic acid (AA), and the electrocatalytic current increased linearly with the concentration of DA (or AA) in the range of 1.0–10.0 mmol·L?1 (for DA) or 0.5–20.0 mmol·L?1 (for AA). 相似文献
8.
9.
Mao‐Chuan Yuan Ping‐I Shih Chen‐Han Chien Ching‐Fong Shu 《Journal of polymer science. Part A, Polymer chemistry》2007,45(14):2925-2937
We have synthesized a blue‐light‐emitting polyfluorene (PF) derivative ( PF‐CBZ‐OXD ) that presents bulky hole‐transporting carbazole and electron‐transporting oxadiazole pendent groups functionalized at the C‐9 positions of alternating fluorene units. The results from photoluminescence and electrochemical measurements indicate that both the side chains and the PF main chain retain their own electronic characteristics in the copolymer. An electroluminescent device incorporating this polymer as the emitting layer was turned on at 4.5 V; it exhibited a stable blue emission with a maximum external quantum efficiency of 1.1%. Moreover, we doped PF‐CBZ‐OXD and its analogue PF‐TPA‐OXD with a red‐light‐emitting iridium phosphor for use as components of phosphorescent red‐light emitters to investigate the effect of the host's HOMO energy level on the degree of charge trapping and on the electrophosphorescent efficiency. We found that spectral overlap and individual energy level matching between the host and guest were both crucial features affecting the performance of the electroluminescence devices. Atomic force microscopy measurements indicated that the dipolar nature of PF‐CBZ‐OXD , in contrast to the general nonpolarity of polydialkylfluorenes, provided a stabilizing environment that allowed homogeneous dispersion of the polar iridium triplet dopant. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2925–2937, 2007 相似文献
10.