全文获取类型
收费全文 | 330805篇 |
免费 | 20261篇 |
国内免费 | 11296篇 |
专业分类
化学 | 193903篇 |
晶体学 | 4413篇 |
力学 | 16441篇 |
综合类 | 593篇 |
数学 | 38697篇 |
物理学 | 108315篇 |
出版年
2022年 | 3879篇 |
2021年 | 5052篇 |
2020年 | 5859篇 |
2019年 | 5878篇 |
2018年 | 6715篇 |
2017年 | 6616篇 |
2016年 | 8970篇 |
2015年 | 7315篇 |
2014年 | 9339篇 |
2013年 | 16421篇 |
2012年 | 17270篇 |
2011年 | 19147篇 |
2010年 | 13062篇 |
2009年 | 12686篇 |
2008年 | 15085篇 |
2007年 | 14640篇 |
2006年 | 13601篇 |
2005年 | 14735篇 |
2004年 | 12685篇 |
2003年 | 10011篇 |
2002年 | 8312篇 |
2001年 | 8497篇 |
2000年 | 6692篇 |
1999年 | 5649篇 |
1998年 | 4824篇 |
1997年 | 4659篇 |
1996年 | 4852篇 |
1995年 | 4080篇 |
1994年 | 4138篇 |
1993年 | 3721篇 |
1992年 | 3868篇 |
1991年 | 3847篇 |
1990年 | 3470篇 |
1989年 | 3161篇 |
1988年 | 3007篇 |
1987年 | 2867篇 |
1986年 | 2886篇 |
1985年 | 3606篇 |
1984年 | 3592篇 |
1983年 | 2937篇 |
1982年 | 3176篇 |
1981年 | 2911篇 |
1980年 | 2677篇 |
1979年 | 2826篇 |
1978年 | 3021篇 |
1977年 | 3058篇 |
1976年 | 3087篇 |
1975年 | 2824篇 |
1974年 | 2945篇 |
1973年 | 2983篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Vysotskii S. L. Kozhevnikov A. V. Filimonov Yu. A. 《Physics of the Solid State》2021,63(10):1579-1583
Physics of the Solid State - The interference of excited and received by current antennae magnetoelastic waves counterpropagating in an yttrium iron garnet film is experimentally studied. It is... 相似文献
23.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献
24.
Dr. Ruijuan Yao Prof. Di Liu Dr. Huihui Wan Dr. Yongqiang Mei Jiahui Wang Dr. Rui Cai Dr. Huimin Zhang Dr. Yuzhen Zhao Dr. Zemin He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(71):e202202269
By linking the carbazole unit to the nitrogen atom of acridone through phenyl or pyridyl, two compounds, named 10-(4-(9H-carbazol-9-yl)phenyl)acridin-9(10H)-one (AC-Ph-Cz) and 10-(5-(9H-carbazol-9-yl)pyridin-2-yl)acridin-9(10H)-one (AC-Py-Cz) were designed and synthesized. These two materials, characterized with highly twisted and rigid structure, good thermal stability, and balanced carrier-transporting properties, were employed as host materials for green phosphorescent and thermally activated delayed fluorescent organic light-emitting diodes (OLEDs). The carbazole group, despite its small contribution to the highest occupied molecular orbitals (HOMOs) of these two materials, plays an essential role as an intramolecular host in energy delivering and improving the hole transporting ability of these two hosts. The incorporation of the electron-deficient pyridyl group as a linking group slightly improves the electron transporting capability of AC-Py-Cz. The green phosphorescent OLED (PhOLED) based on AC-Py-Cz exhibited excellent device performance with a turn-on voltage of 2.5 V, a maximum power efficiency and an external quantum efficiency (ηext) of 89.8 lm W−1 and 25.2 %, respectively, benefitting from the better charge-balancing ability of AC-Py-Cz host due to the presence of the pyridyl bridge. More importantly, all the devices based on these two hosts showed low efficiency roll-off at high brightness due to the suppressed non-radiative transition in the emitting layer. In particular, the AC-Py-Cz-hosted green PhOLED exhibited an efficiency roll-off of 1.6 % from the maximum next at a high brightness of 1000 cd m−2 and a roll-off of 15.9 % at an extremely high brightness of 10000 cd m−2. This study manifests that acridone-based host materials have great potential in fabricating OLEDs with low efficiency roll-off. 相似文献
25.
Physics of the Solid State - Local internal stresses in two natural inhomogeneous materials differing in the structure have been calculated using analysis of pauses between acoustic emission... 相似文献
26.
Daulbaev O. Isaenko L. I. Bogdzel’ A. A. Lobanov S. I. Krinitsyn P. G. Milkov V. M. Belushkin A. V. 《Crystallography Reports》2022,67(3):464-469
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using... 相似文献
27.
Vasile M. Loots H. Vercammen L. Bruggeman M. Verrezen F. 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(8):3349-3357
Journal of Radioanalytical and Nuclear Chemistry - In this paper a study for the selection of an NPE (nonylphenol ethoxylates)—free cocktail is discussed in order to be used for our routine... 相似文献
28.
Hongjin Wang Tengfei Long Hao Zhang Meng Li Qi Sun Xin Zhai Lixin Sun 《Biomedical chromatography : BMC》2022,36(4):e5301
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
29.
Radiophysics and Quantum Electronics - A well-known simplified model of turbulent convection from local sources of buoyancy and/or momentum acting for a short time has been developed and... 相似文献
30.
The molecular geometries and dissociation energies of AnO (An = Bk–Lr) molecules were first obtained at thecoupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] level of theory. Four hybrid functionals,B3LYP, M06-2X, TPSSh, and PBE0, were also employed in the calculations for the sake of comparison. In comparison ofthe CCSD(T) results, B3LYP, TPSSh, and PBE0 functionals can obtain more appropriate results than M06-2X and MP2.The analyses on molecular orbitals show that the 7s, 6d, and 5f atomic orbitals of actinide (An) atoms participate in thebonding of An–O bonds. The partial covalent nature between An and O atoms is revealed by QTAIM analyses. 相似文献