全文获取类型
收费全文 | 9775篇 |
免费 | 1252篇 |
国内免费 | 1191篇 |
专业分类
化学 | 7919篇 |
晶体学 | 136篇 |
力学 | 373篇 |
综合类 | 94篇 |
数学 | 954篇 |
物理学 | 2742篇 |
出版年
2024年 | 19篇 |
2023年 | 115篇 |
2022年 | 217篇 |
2021年 | 287篇 |
2020年 | 312篇 |
2019年 | 329篇 |
2018年 | 254篇 |
2017年 | 303篇 |
2016年 | 451篇 |
2015年 | 455篇 |
2014年 | 560篇 |
2013年 | 686篇 |
2012年 | 820篇 |
2011年 | 931篇 |
2010年 | 656篇 |
2009年 | 583篇 |
2008年 | 743篇 |
2007年 | 606篇 |
2006年 | 620篇 |
2005年 | 535篇 |
2004年 | 433篇 |
2003年 | 363篇 |
2002年 | 419篇 |
2001年 | 289篇 |
2000年 | 218篇 |
1999年 | 199篇 |
1998年 | 136篇 |
1997年 | 117篇 |
1996年 | 69篇 |
1995年 | 69篇 |
1994年 | 48篇 |
1993年 | 48篇 |
1992年 | 39篇 |
1991年 | 47篇 |
1990年 | 31篇 |
1989年 | 21篇 |
1988年 | 33篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 15篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1975年 | 4篇 |
1969年 | 2篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Rong‐Min Wang Nai‐Pu He Yu‐Feng He Yun‐Tao Xie Yun‐Pu Wang Eishun Tsuchida 《先进技术聚合物》2005,16(8):638-641
Water‐soluble low molecular weight chitosan of nanometer level and its copper complexes were prepared, and characterized by IR spectra, elemental analysis and gel permeation chromatography (GPC). The modes and mechanism of these copper complexes interaction with DNA were studied by a fluorescent probe method and electrophoresis analysis. It is suggested that there are electrostatic and intercalation modes of copper complexes interacting with DNA. At first, the cationic complex electrostaticly binds to the negatively charged phosphate backbone of DNA, and then a portion of the complex intercalates between the base pairs on the DNA duplex strand. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
102.
Bamboo-shaped Ag-doped TiO2 nanowires with heterojunctions were synthesized by a simple solvothermal method. The diameter of the nanowires was about 50-100 nm, and they had a length of up to a few millimeters. The detailed structure of the heterojunction in the nanowire was also characterized. 相似文献
103.
104.
利用蒙特卡洛模拟方法对线形链和星形键在亚浓溶液区的标度律作了验证与讨论。我们的计算结果证明线形链渗透压Π与体积分数Φ在亚浓溶液区的标度规律是与德热纳的理论结果相一致的。同时还证明了星形链在亚浓溶液区具有与线形链相同的标度行为。 相似文献
105.
IntroductionInthepastdecade ,itwasfoundthattwoaminoacidresidues ,SerandHis ,workastheactivesitesintheser ineprotease .1 3 Inourpreviouswork ,adipeptideseryl histidine (Ser His)wasfoundtohavetheproteinandnu cleosidescleavageactivity .4 7p Nitrophenylacetate (p NPA)w… 相似文献
106.
107.
IntroductionElectrontransferreactionsarethekeystepsinphoto synthesis ,respirationandmanyotherbiochemicalprocess es.1Cytochromeb5isaredoxproteinexistingwidelyinnature ,whichactsasanelectron carrierduringvariouselectrontransferprocessesinthebiologicalsystem .2Cytochromeb5isamembraneproteinwithmolecularweightofapproximately 16kDa ,ofwhichthehydrophobicC terminaldomainanchorscytochromeb5tothemem brane ,andthehydrophilicN terminaldomaincontainshemeprostheticgroupandexhibitsthebiologicalfunctionsof… 相似文献
108.
Li YS Xiao Y Wright PB Tran T 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(7):1675-1681
3-(Triethoxysilyl)propionitrile (TESPN) sol-gel has been prepared under different conditions. It was employed for coating the surfaces of quartz and aluminum. Infrared (IR) and Raman spectra of TESPN and TESPN sol-gels have been recorded in the study of the sol-gel process. Transmission and reflection absorption IR (RAIR) spectra of TESPN sol-gel coated quartz and aluminum have also been collected for better understanding the film formation on the substrate surfaces. Spectra collected at different temperatures indicated that the silane film on quartz decomposes at 700 degrees C. Results from thermal gravimetric analysis (TGA) supported this result. Based on the group frequencies and the spectral behavior in different states, some vibrational modes were assigned to the observed bands. The anticorrosion behavior of the sol-gel coated aluminum in comparison with the uncoated metal was evaluated by measuring the potentiodynamic polarization and electrochemical impedance spectra (EIS). 相似文献
109.
110.
Separation of salidroside from Rhodiola crenulata by high-speed counter-current chromatography 总被引:3,自引:0,他引:3
High-speed counter-current chromatography (HSCCC) was used to purify salidroside from an extract of Rhodiola crenulata with two steps using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:4:5, v/v) in the first run and chloroform-methanol-isopropanol-water (5:6:1:4) in the second run. The method yielded 21.9 mg of salidroside from 1.216 g of the crude sample at 98% purity determined by HPLC analyses. Identification was performed by 1H NMR, 13C NMR, and MS. 相似文献