全文获取类型
收费全文 | 31391篇 |
免费 | 4607篇 |
国内免费 | 6014篇 |
专业分类
化学 | 25556篇 |
晶体学 | 575篇 |
力学 | 1378篇 |
综合类 | 515篇 |
数学 | 3501篇 |
物理学 | 10487篇 |
出版年
2024年 | 40篇 |
2023年 | 370篇 |
2022年 | 604篇 |
2021年 | 887篇 |
2020年 | 987篇 |
2019年 | 1076篇 |
2018年 | 902篇 |
2017年 | 915篇 |
2016年 | 1317篇 |
2015年 | 1466篇 |
2014年 | 1787篇 |
2013年 | 2479篇 |
2012年 | 2712篇 |
2011年 | 2882篇 |
2010年 | 2247篇 |
2009年 | 2112篇 |
2008年 | 2551篇 |
2007年 | 2302篇 |
2006年 | 2112篇 |
2005年 | 1757篇 |
2004年 | 1543篇 |
2003年 | 1313篇 |
2002年 | 1409篇 |
2001年 | 1176篇 |
2000年 | 949篇 |
1999年 | 727篇 |
1998年 | 483篇 |
1997年 | 423篇 |
1996年 | 381篇 |
1995年 | 338篇 |
1994年 | 293篇 |
1993年 | 259篇 |
1992年 | 225篇 |
1991年 | 173篇 |
1990年 | 169篇 |
1989年 | 115篇 |
1988年 | 94篇 |
1987年 | 79篇 |
1986年 | 71篇 |
1985年 | 63篇 |
1984年 | 46篇 |
1983年 | 34篇 |
1982年 | 20篇 |
1981年 | 24篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
951.
TETRABUTYLAMMONIUM-TETRACYANOQUINODIMETHANEASELECTRON-TRANSFERMEDIATORINAMPEROMETRICGLUCOSESENSOR¥ChangQingSUN;WenBeSONG;DuoZ... 相似文献
952.
953.
ChangLuSHAO HongYuGUAN ShangBinWEN BinCHEN XingHuaYANG JianGONG YiChunLIU 《中国化学快报》2004,15(4):492-494
Thin PVA/cobalt acetate composite fibers were prepared by using sol-gel processing and electrospinning technique.After calcination of the above precursor fibers,Co3O4 nanofibers with a diameter of 50-150 nm could be successfully obtained.The fibers were characterized by SEM,FT-IR,WAXD,respectively. 相似文献
954.
The growth ofBacillus amyloliquefaciens in the aqueous two-phase system, made up of polyethylene glycol, dextran, and water, was investigated. Generally,Bacillus partitions in the dextran phase, but the magnitude of the separation depends largely on the overall composition of polymers
in the phase system. The kinetics of growth ofBacillus amyloliquefaciens was studied in the polyethylene glycol-rich continuous phase, dextran-rich dispersed phase, and in the mixed phase. From
the kinetic data it appears that increasing the overall polymer composition causes the cells to adsorp at the interface. On
the other hand, partition measurements indicate that increasing polymer concentrations make the cell partitioning more one-sided.
This anomaly is explained by studying the interfacial adsorption of cells via dynamic surface tension measurements. 相似文献
955.
A composite film of ethylenediamine tetraacetic acid (EDTA)‐ZrO2 organic‐inorganic hybrid was prepared based on the chelation between Zr(IV) and EDTA. The direct electrochemical behavior of cytochrome c (cyt. c) at the hybrid film modified glassy carbon electrodes was investigated. The immobilized EDTA can promote the redox of heme in horse heart cyt. c which gives rise to a pair of reversible redox peaks with a formal potential of 40 mV (vs. SCE). The peak current increased linearly with the increase of cyt. c concentration in the range of 1.6 × 10?6—8.0 × 10?5 mol·L?1 with the correlation coefficient of 0.996. Further investigation shows that metal ions can impede the electron transfer of cyt. c. The impediment capability of metal ions depends on their coordination capability with EDTA and their valence number. 相似文献
956.
Six‐membered cyclic α‐aminonitrile has been prepared from anodic cyanation of N‐benzylpiperidine. Good yields of α‐aminonitriles could be obtained through potentiostatic electrolysis under different conditions. The results also explain why high yield α‐aminonitriles could not be obtained under constant current electrolysis. 相似文献
957.
Polymer-supported phosphine ligand 3b derived from ferrocene was prepared,and applied in palladium-catalyzed Suzuki- Miyaura reactions.A range of aryl bromides can couple with phenylboronic acid to obtain corresponding biaryls in excellent yields. The recycling of the polymer-bound catalyst was tested without adding palladium. 相似文献
958.
959.
An ortho substituent group has a significant effect on thermal decomposition of aryltriazenes. When the ortho methoxy-substituted phenyltriazenes were treated with methyl iodide at 110-130 °C, 1,5-H shift products were obtained in fair to moderate yields. 相似文献
960.