首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11331篇
  免费   1855篇
  国内免费   1999篇
化学   8608篇
晶体学   117篇
力学   666篇
综合类   137篇
数学   1468篇
物理学   4189篇
  2024年   7篇
  2023年   272篇
  2022年   330篇
  2021年   401篇
  2020年   559篇
  2019年   526篇
  2018年   409篇
  2017年   441篇
  2016年   577篇
  2015年   588篇
  2014年   673篇
  2013年   921篇
  2012年   911篇
  2011年   1040篇
  2010年   758篇
  2009年   702篇
  2008年   795篇
  2007年   666篇
  2006年   618篇
  2005年   558篇
  2004年   466篇
  2003年   374篇
  2002年   406篇
  2001年   303篇
  2000年   284篇
  1999年   245篇
  1998年   198篇
  1997年   140篇
  1996年   167篇
  1995年   126篇
  1994年   143篇
  1993年   102篇
  1992年   74篇
  1991年   96篇
  1990年   96篇
  1989年   41篇
  1988年   39篇
  1987年   23篇
  1986年   25篇
  1985年   31篇
  1984年   9篇
  1983年   16篇
  1982年   8篇
  1981年   7篇
  1980年   4篇
  1979年   2篇
  1971年   1篇
  1957年   3篇
  1936年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Zhai  Shidong  Gao  Hui  Luo  Guoqiang  Tao  Junli 《Nonlinear dynamics》2021,106(2):1133-1147
Nonlinear Dynamics - This paper introduces a multigroup COVID-19 model with immunity, in which the total population of each group is partitioned into five compartments, that is, susceptible,...  相似文献   
2.
Song  Zi-Long  Zhu  Yun  Liu  Jing-Rui  Guo  Shu-Ke  Gu  Yu-Cheng  Han  Xinya  Dong  Hong-Qiang  Sun  Qi  Zhang  Wei-Hua  Zhang  Ming-Zhi 《Molecular diversity》2021,25(1):205-221
Molecular Diversity - Based on the strategy of diversity-oriented synthesis and the structures of natural product pimprinine and streptochlorin, two series of novel pimprinine derivatives...  相似文献   
3.
Guo  Jiayun  Ma  Dongge  Sun  Fulin  Zhuang  Guilin  Wang  Qi  Al-Enizi  Abdullah M.  Nafady  Ayman  Ma  Shengqian 《中国科学:化学(英文版)》2022,65(9):1704-1709
Science China Chemistry - The heterojunction constructed of covalent organic frameworks (COFs) with adjustable structure and other photocatalysts has great potential in the field of photocatalysis....  相似文献   
4.
3,4-Difluorobenzyl(1-ethyl-5-(4-((4-hydroxypiperidin-1-yl)-methyl)thiazol-2-yl)-1H-indol-3-yl)carbamate (NAI59), a small molecule with outstanding therapeutic effectiveness to anti-pulmonary fibrosis, was developed as an autotaxin inhibitor candidate compound. To evaluate the pharmacokinetics and plasma protein binding of NAI59, a UPLC–MS/MS method was developed to quantify NAI59 in plasma and phosphate-buffered saline. The calibration curve linearity ranged from 9.95 to 1990.00 ng/mL in plasma. The accuracy was −6.8 to 5.9%, and the intra- and inter-day precision was within 15%. The matrix effect and recovery, as well as dilution integrity, were within the criteria. The chromatographic and mass spectrometric conditions were also feasible to determine phosphate-buffered saline samples, and it has been proved that this method exhibits good precision and accuracy in the range of 9.95–497.50 ng/mL in phosphate-buffered saline. This study is the first to determine the pharmacokinetics, absolute bioavailability, and plasma protein binding of NAI59 in rats using this established method. Therefore, the pharmacokinetic profiles of NAI59 showed a dose-dependent relationship after oral administration, and the absolute bioavailability in rats was 6.3%. In addition, the results of protein binding showed that the combining capacity of NAI59 with plasma protein attained 90% and increased with the increase in drug concentration.  相似文献   
5.
Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived...  相似文献   
6.
Refractory wounds have always been an important issue to healthcare systems, whose healing process is always delayed by multiple factors, including bacterial infections, chronic inflammation, and excessive exudates, etc. Employing multifunctional wound dressings is recognized as an effective strategy to deal with refractory wounds, which has yielded promising outcomes in recent years. Among these advanced wound dressings, fibrous dressings have gained growing attention due to their unique merits. Such wound dressings have demonstrated great potential in delivering theranostic agents, such as antibacterial agents, anti-inflammatory drugs, growth factors, and diagnostic probes, etc., for the purposes of accelerating wound healing. This paper reviews the development of multifunctional fibrous dressings and their applications in treating refractory wounds. The construction approaches of novel fibrous dressing with capabilities of antibacterial, anti-inflammation, exudate management and diagnosis were also introduced. Furthermore, the existing problems and challenges are also discussed briefly.  相似文献   
7.
Journal of Applied Mechanics and Technical Physics - A self-equilibrated stress field for an incompressible sphere is constructed based on a non-Euclidean continuum model. The...  相似文献   
8.
随着供热计量系统的普及,系统可以根据负荷的变化进行调整,管网的阻力系数随即发生变化。对变动阻力系数进行优化辨识是了解供热管网实时运行状况的有效手段。提出一种基于流量监测数据的供热管网变动阻力系数优化辨识方法,并利用遗传算法进行求解。对洛阳市某小区供暖季管网实际运行数据进行验证,辨识结果的相对误差在5%以内。结果表明:该方法可以在只有流量观测数据时得到精度较高的供热管网变动阻力系数,为供热系统的运行调节提供指导。  相似文献   
9.
10.
Zhang  Jian  Qi  Naiming  Jiang  Jihai 《Fluid Dynamics》2021,56(3):371-382
Fluid Dynamics - The collapse of cavitation bubbles in a hydraulic system generates localized zones of high temperature and pressure and, under certain conditions, luminescence. In this study, we...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号