全文获取类型
收费全文 | 6194篇 |
免费 | 681篇 |
国内免费 | 385篇 |
专业分类
化学 | 4509篇 |
晶体学 | 82篇 |
力学 | 275篇 |
综合类 | 23篇 |
数学 | 751篇 |
物理学 | 1620篇 |
出版年
2023年 | 106篇 |
2022年 | 148篇 |
2021年 | 183篇 |
2020年 | 186篇 |
2019年 | 163篇 |
2018年 | 148篇 |
2017年 | 125篇 |
2016年 | 225篇 |
2015年 | 213篇 |
2014年 | 276篇 |
2013年 | 359篇 |
2012年 | 439篇 |
2011年 | 514篇 |
2010年 | 290篇 |
2009年 | 294篇 |
2008年 | 402篇 |
2007年 | 378篇 |
2006年 | 373篇 |
2005年 | 305篇 |
2004年 | 252篇 |
2003年 | 232篇 |
2002年 | 209篇 |
2001年 | 137篇 |
2000年 | 105篇 |
1999年 | 137篇 |
1998年 | 121篇 |
1997年 | 117篇 |
1996年 | 111篇 |
1995年 | 110篇 |
1994年 | 90篇 |
1993年 | 45篇 |
1992年 | 55篇 |
1991年 | 48篇 |
1990年 | 38篇 |
1989年 | 35篇 |
1988年 | 34篇 |
1987年 | 27篇 |
1986年 | 23篇 |
1985年 | 28篇 |
1984年 | 27篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 23篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 11篇 |
排序方式: 共有7260条查询结果,搜索用时 46 毫秒
961.
Fang Tao Chen Xiuting Wang Miao Wang Yanan Liao Lixia Li Bin 《Research on Chemical Intermediates》2020,46(12):5459-5477
Research on Chemical Intermediates - In recent years, how to improve photocatalytic performance under visible light has become one of the research hot topics. The nano-TiO2 particles were... 相似文献
962.
Gang Li Libo Liao Xinchou Lou Peixun Shen Weimin Song Shudong Wang Zhaoling Zhang 《中国物理C(英文版)》2022,46(11):113001-113001-8
Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a model- independent way. In this study, the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories, and the ultimate goal is to realize an "end-to-end" analysis. A Monte Carlo simulation study is performed to demonstrate the feasibility, and the performance looks rather promising. This result could be the basis of a "one-stop" analysis to measure all the branching fractions of the Higgs decays simultaneously. 相似文献
963.
Brandon C. Presley Marisol S. Castaneto Barry K. Logan Susan A. Jansen-Varnum 《Biomedical chromatography : BMC》2020,34(9):e4884
FUB-AMB, an indazole carboxamide synthetic cannabinoid recreational drug, was one of the compounds most frequently reported to governmental agencies worldwide between 2016 and 2019. It has been implicated in intoxications and fatalities, posing a risk to public health. In the current study, FUB-AMB was incubated with human liver microsomes (HLM) to assess its metabolic fate and stability and to determine if its major ester hydrolysis metabolite (M1) was present in 12 authentic forensic human blood samples from driving under the influence of drug cases and postmortem investigations using UHPLC–MS/MS. FUB-AMB was rapidly metabolized in HLM, generating M1 that was stable through a 120-min incubation period, a finding that indicates a potential long detection window in human biological samples. M1 was identified in all blood samples, and no parent drug was detected. The authors propose that M1 is a reliable marker for inclusion in laboratory blood screens for FUB-AMB; this metabolite may be pharmacologically active like its precursor FUB-AMB. M1 frequently appears in samples in which the parent drug is undetectable and can point to the causative agent. The results suggest that it is imperative that synthetic cannabinoid laboratory assay panels include metabolites, especially known or potential pharmacologically active metabolites, particularly for compounds with short half-lives. 相似文献
964.
965.
Nonlinear Dynamics - The continuation and stability analysis methods for quasi-periodic solutions of nonlinear systems are proposed. The proposed continuation method advances the... 相似文献
966.
967.
968.
Herein we report a novel visible-light-mediated external reductant-free reductive cross coupling for the construction of C sp~2–C sp~3 bonds. A variety of benzylammonium salts underwent selective coupling with(hetero)aryl nitriles to deliver important diarylmethanes under mild reaction conditions. Importantly, photocatalysts can be omitted for many cases, which might involve the electron donor acceptor(EDA) complex. Mechanistic studies indicated benzylic radicals might be involved as the key intermediates. Moreover, the in situ generated NMe_3 via cleavage of C–N bond in ammonium salts acts as the electron donor,thus avoiding the use of external-reductant. 相似文献
969.
Gong Hengfeng Xiao Hong Wu Hailong Meng Fanliang Ren Qisen Liao Yehong Zhang Guoliang 《The European Physical Journal B - Condensed Matter and Complex Systems》2022,95(8):1-7
The European Physical Journal B - Molecular dynamics and Monte Carlo methods are common measurements to study the diffusion coefficients of the fluid particles under restricted conditions. Here,... 相似文献
970.