全文获取类型
收费全文 | 8634篇 |
免费 | 1302篇 |
国内免费 | 1289篇 |
专业分类
化学 | 6263篇 |
晶体学 | 101篇 |
力学 | 674篇 |
综合类 | 110篇 |
数学 | 1140篇 |
物理学 | 2937篇 |
出版年
2024年 | 25篇 |
2023年 | 168篇 |
2022年 | 214篇 |
2021年 | 287篇 |
2020年 | 324篇 |
2019年 | 310篇 |
2018年 | 229篇 |
2017年 | 253篇 |
2016年 | 426篇 |
2015年 | 355篇 |
2014年 | 444篇 |
2013年 | 601篇 |
2012年 | 731篇 |
2011年 | 688篇 |
2010年 | 561篇 |
2009年 | 476篇 |
2008年 | 529篇 |
2007年 | 448篇 |
2006年 | 437篇 |
2005年 | 423篇 |
2004年 | 363篇 |
2003年 | 336篇 |
2002年 | 388篇 |
2001年 | 357篇 |
2000年 | 252篇 |
1999年 | 260篇 |
1998年 | 193篇 |
1997年 | 186篇 |
1996年 | 195篇 |
1995年 | 145篇 |
1994年 | 138篇 |
1993年 | 102篇 |
1992年 | 73篇 |
1991年 | 73篇 |
1990年 | 45篇 |
1989年 | 29篇 |
1988年 | 39篇 |
1987年 | 20篇 |
1986年 | 29篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1957年 | 3篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Yong Deng Da Cheng Yang Yi Shen Yu Guo Zhong 《中国化学快报》2007,18(1):7-9
Based on the structure-activity relationships and antiangiogenic mechanism of RGD-containing peptides,a series of 5-amino- 1,3-dihydro-1,3-dioxo-2H-isoindole derivatives were synthesized.The structures were characterized by ~1H NMR,MS and elementary analysis.There ability to inhibit angiogenesis were evaluated by chick embryo chorioallantoic membrane assay at 10~(-5) mol/L.Compounds 7a and 7b displayed obvious antiangiogenic activity. 相似文献
993.
994.
Su-Qin Chen Qian-Mei Wang Ping-Chuan Xu Shao-Peng Ge Ping Zhong 《Phosphorus, sulfur, and silicon and the related elements》2016,191(1):100-103
A simple method was developed for the synthesis of 3-chalcogen indoles via iodine-promoted direct 3-selanyl- and 3-sulfenylation of indoles with dichalcogenides. The reaction was carried out smoothly in EtOH under air at room temperature, selectively giving a series of 3-chalcogen indoles bearing different functional groups in good to excellent yields. The procedure has the merits of environmental friendliness, easy operation, wide substrate scope and mild reaction conditions. 相似文献
995.
Real‐Time Probing of Nanowire Assembly Kinetics at the Air–Water Interface by In Situ Synchrotron X‐Ray Scattering 下载免费PDF全文
Zhen He Dr. Hui‐Jun Jiang Long‐Long Wu Dr. Jian‐Wei Liu Dr. Geng Wang Xiao Wang Dr. Jin‐Long Wang Prof. Zhong‐Huai Hou Prof. Gang Chen Prof. Shu‐Hong Yu 《Angewandte Chemie (International ed. in English)》2018,57(27):8130-8134
Although many assembly strategies have been used to successfully construct well‐aligned nanowire (NW) assemblies, the understanding of their assembly kinetics has remained elusive, which restricts the development of NW‐based device and circuit fabrication. Now a versatile strategy that combines interfacial assembly and synchrotron‐based grazing‐incidence small‐angle X‐ray scattering (GISAXS) is presented to track the assembly evolution of the NWs in real time. During the interface assembly process, the randomly dispersed NWs gradually aggregate to form small ordered NW‐blocks and finally are constructed into well‐defined NW monolayer driven by the conformation entropy. The NW assembly mechanism can be well revealed by the thermodynamic analysis and large‐scale molecular dynamics theoretical evaluation. These findings point to new opportunities for understanding NW assembly kinetics and manipulating NW assembled structures by bottom‐up strategy. 相似文献
996.
A simple, rapid and reliable high-performance liquid chromatographic method was developed and validated for the determination of pirfenidone and its major metabolites in rat plasma. Plasma proteins were precipitated with perchloric acid (10%, v/v) and the supernatant after centrifugation was determined using high-performance liquid chromatography. The analysis was carried out on a Lichrospher C(18) column (250 x 4.6 mm i.d., 5 microm). The mobile phase consisted of acetonitrile-water containing 0.2% acetic acid (23:77, v/v) at a flow-rate of 1 mL/min. The eluant was detected at 310 nm. The calibration curves were linear over a concentration range from 0.15 to 76.67 microg/mL. The accuracy (relative error) of the assay ranged from -2.6 to 7.9% and the precision (coefficient of variation) was less than 4.5%. The established method has been successfully applied to a pharmacokinetic study of pirfenidone following a single oral dose to rats. 相似文献
997.
研究了南美白对虾苗中4种硝基呋喃代谢物呋喃唑酮代谢物(AOZ)、呋喃它酮代谢物(AMOZ)、呋喃妥因代谢物(AHD)、呋喃西林代谢物(SEM)的高效液相色谱–串联质谱(HPLC–MS/MS)测定方法。以水解衍生并添加4种同位素内标的方法对样品进行处理,补偿了衍生化效率,提高了定量的准确性。实验结果表明,AOZ,AMOZ的检出限为0.10μg/kg,SEM,AHD的检出限为0.25μg/kg;AOZ,AMOZ的定量下限为0.40μg/kg,SEM,AHD的定量下限为0.50μg/kg。方法加标回收率在88.2%~97.6%之间,相对标准偏差在4.6%~8.1%(n=6)之间。该法检测灵敏度高,测量结果的精密度和准确度满足药物残留检测要求。 相似文献
998.
999.
考虑铁基超导中能带间的相互作用和界面对每一个能带的散射作用, 利用推广的Blonder-Tinkham-Klapwijk模型, 并通过求解Bogoliubov-de Gennes 方程研究了具有不同类型双能隙系统的量子线/铁基超导隧道结中准粒子的输运系数和隧道谱. 研究表明: 1)在弹道极限时, 随着带间相互作用的增大, s± 波隧道谱中零偏压附近的平台演变成电导峰; s++ 波的平台演变成凹陷; p波的零偏压电导峰被压低. 2)界面对两个能带的散射作用不为零时, 随着带间相互作用的增大, s± 波和s++ 波两能隙处的峰值将降低, 而两峰间的凹陷值将变大; p波的零偏压电导峰被压低, 非零偏压电导增大. 3)界面对每个能带的散射, 可使其产生的电导峰变得更加尖锐, 但可压低和抹平另一个带产生的电导峰值. 这些结果对于澄清铁基超导体的能隙结构和区别不同类型铁基超导体有所帮助. 相似文献
1000.
该文利用不动点指数理论讨论了Banach空间中一类带奇异性的脉冲微分方程Neumann边值问题多解的存在性,并给出了应用 相似文献