全文获取类型
收费全文 | 5705篇 |
免费 | 329篇 |
国内免费 | 65篇 |
专业分类
化学 | 4160篇 |
晶体学 | 49篇 |
力学 | 124篇 |
综合类 | 1篇 |
数学 | 656篇 |
物理学 | 1109篇 |
出版年
2023年 | 29篇 |
2022年 | 59篇 |
2021年 | 119篇 |
2020年 | 111篇 |
2019年 | 138篇 |
2018年 | 113篇 |
2017年 | 92篇 |
2016年 | 204篇 |
2015年 | 180篇 |
2014年 | 209篇 |
2013年 | 360篇 |
2012年 | 381篇 |
2011年 | 430篇 |
2010年 | 294篇 |
2009年 | 250篇 |
2008年 | 363篇 |
2007年 | 301篇 |
2006年 | 296篇 |
2005年 | 301篇 |
2004年 | 230篇 |
2003年 | 214篇 |
2002年 | 193篇 |
2001年 | 122篇 |
2000年 | 109篇 |
1999年 | 58篇 |
1998年 | 48篇 |
1997年 | 55篇 |
1996年 | 74篇 |
1995年 | 51篇 |
1994年 | 46篇 |
1993年 | 61篇 |
1992年 | 50篇 |
1991年 | 43篇 |
1990年 | 42篇 |
1989年 | 54篇 |
1988年 | 29篇 |
1987年 | 29篇 |
1986年 | 36篇 |
1985年 | 34篇 |
1984年 | 22篇 |
1983年 | 17篇 |
1982年 | 21篇 |
1981年 | 30篇 |
1980年 | 20篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1977年 | 23篇 |
1976年 | 23篇 |
1975年 | 18篇 |
1974年 | 20篇 |
排序方式: 共有6099条查询结果,搜索用时 694 毫秒
71.
Tae Oan Ahn Jung Ho Kim Jong Chan Lee Han Mo Jeong Jong-Yoon Park 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):435-441
A macro-azoinitiator containing polyarylate segment and azo group was prepared by the solution polycondensation of azobiscyanopentanoyl chloride and hydroxy-terminated polyarylates having viscosity-average molecular weights of 6200, 8100, and 12 400. These macro-azoinitiators were used in the radical polymerization of styrene to synthesize polyarylate-polystyrene block copolymers. Thermal properties measured by the differential scanning calorimetry indicated the phase separated morphology of the block copolymers except at low molecular weight of the block constituents. © 1993 John Wiley & Sons, Inc. 相似文献
72.
73.
74.
75.
76.
Summary Real hypersurfaces of an almost Hermitian manifold naturally admit an almost contact metric structure and the (f, g, u, v, w, , , )-structure is defined on submanifolds of codimension 3 of an almost Hermitian manifold. We study the so-called semi-invariant submanifolds of a complex space form with almost contact metric compound structure which is a general notion of (f, g, u, v, w, , , )-structure.Dedicated to professor Eulyong Pak on his 60th birthdayThis research was partially supported by Korean Science and Engineering Foundation Grant. 相似文献
77.
Kwak WJ Han CK Chang HW Kim HP Kang SS Son KH 《Chemical & pharmaceutical bulletin》2003,51(3):333-335
A new triterpenoid saponin, loniceroside C was isolated from the aerial parts of Lonicera japonica. Its structure was established to be 3-O-beta-D-glucopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1-->2)-[beta-D-xylopyranosyl(1-->6)]-beta-D-glucopyranosyl ester by spectroscopic techniques and chemical transformations. Loniceroside C showed in vivo antiinflammatory activity against mouse ear edema provoked by croton oil. 相似文献
78.
A method combining the techniques of liquid – solid disk extraction (LSDE) and supercritical fluid elution (SFE) has been developed for the phenols regulated by the Clean Water Act. LSDE uses a disk or membrane made of polytetrafluoroethylene (PTFE) fibrils impregnated with small particles, e.g. styrene divinylbenzene (SDB) resin, to extract phenols from water. After disk extraction the retained analytes are eluted from the disk using SFE. SFE is used as an alternative to liquid solvent elution with an organic solvent. Analytes are separated, identified, and quantified using gas chromatography – ion trap detector mass spectrometry (GC-ITDMS). The method is capable of sub parts per billion detection limits, and precision of 5–28% RSD. Evaluation of various disks or membranes, such as C18-silica disks, SDB disks, and ion exchange membranes, has also been performed for the extraction of phenols from water. The results obtained from the in-situ aqueous acetylation of phenols and extraction of their acetates are quantitative. The utilization of LSDE and SFE techniques has proven to be a more effective approach than liquid – liquid extraction in minimizing air pollution and solvent waste. 相似文献
79.
CHIP-mediated hyperubiquitylation of tau promotes its self-assembly into the insoluble tau filaments
Ji Hyeon Kim Jeeyoung Lee Won Hoon Choi Seoyoung Park Seo Hyeong Park Jung Hoon Lee Sang Min Lim Ji Young Mun Hyun-Soo Cho Dohyun Han Young Ho Suh Min Jae Lee 《Chemical science》2021,12(15):5599
The tau protein is a highly soluble and natively unfolded protein. Under pathological conditions, tau undergoes multiple post-translational modifications (PTMs) and conformational changes to form insoluble filaments, which are the proteinaceous signatures of tauopathies. To dissect the crosstalk among tau PTMs during the aggregation process, we phosphorylated and ubiquitylated recombinant tau in vitro using GSK3β and CHIP, respectively. The resulting phospho–ub-tau contained conventional polyubiquitin chains with lysine 48 linkages, sufficient for proteasomal degradation, whereas unphosphorylated ub-tau species retained only one–three ubiquitin moieties. Mass-spectrometric analysis of in vitro reconstituted phospho–ub-tau revealed seven additional ubiquitylation sites, some of which are known to stabilize tau protofilament stacking in the human brain with tauopathy. When the ubiquitylation reaction was prolonged, phospho–ub-tau transformed into insoluble hyperubiquitylated tau species featuring fibrillar morphology and in vitro seeding activity. We developed a small-molecule inhibitor of CHIP through biophysical screening; this effectively suppressed tau ubiquitylation in vitro and delayed its aggregation in cultured cells including primary cultured neurons. Our biochemical findings point to a “multiple-hit model,” where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process, thus indicating that targeting tau ubiquitylation may be an effective strategy to alleviate the course of tauopathies.Multiple-hit model for tau aggregation, where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process. 相似文献
80.
A general strategy is proposed to assign aliphatic side-chain resonances of large 13C,15N-labeled proteins without deuteration, using 4D 13C,15N-edited NOESY and MQ-(H)CCH-TOCSY experiments on the basis of prior assignments of backbone and 13Cbeta resonances. The strategy has been tested on a 214 residue protein (DdCAD-1) and applied to a chain-selectively 13C,15N-labeled hemoglobin (65 kDa). About 96 and 80% aliphatic side-chain spins in DdCAD-1 and hemoglobin have been assigned, respectively. The strategy proposed here will be very useful for the structure determination and dynamics characterization of large proteins by NMR. 相似文献