全文获取类型
收费全文 | 7764篇 |
免费 | 886篇 |
国内免费 | 758篇 |
专业分类
化学 | 5474篇 |
晶体学 | 86篇 |
力学 | 371篇 |
综合类 | 74篇 |
数学 | 1017篇 |
物理学 | 2386篇 |
出版年
2023年 | 106篇 |
2022年 | 178篇 |
2021年 | 190篇 |
2020年 | 241篇 |
2019年 | 245篇 |
2018年 | 206篇 |
2017年 | 186篇 |
2016年 | 366篇 |
2015年 | 350篇 |
2014年 | 383篇 |
2013年 | 592篇 |
2012年 | 522篇 |
2011年 | 486篇 |
2010年 | 453篇 |
2009年 | 389篇 |
2008年 | 507篇 |
2007年 | 447篇 |
2006年 | 376篇 |
2005年 | 361篇 |
2004年 | 296篇 |
2003年 | 250篇 |
2002年 | 220篇 |
2001年 | 209篇 |
2000年 | 161篇 |
1999年 | 128篇 |
1998年 | 101篇 |
1997年 | 82篇 |
1996年 | 86篇 |
1995年 | 71篇 |
1994年 | 59篇 |
1993年 | 67篇 |
1992年 | 63篇 |
1991年 | 77篇 |
1990年 | 49篇 |
1989年 | 38篇 |
1988年 | 32篇 |
1987年 | 42篇 |
1986年 | 39篇 |
1985年 | 39篇 |
1984年 | 27篇 |
1983年 | 29篇 |
1982年 | 24篇 |
1981年 | 26篇 |
1980年 | 30篇 |
1979年 | 29篇 |
1978年 | 22篇 |
1977年 | 37篇 |
1976年 | 19篇 |
1974年 | 19篇 |
1934年 | 18篇 |
排序方式: 共有9408条查询结果,搜索用时 15 毫秒
161.
We study an application of the Jacobi last multiplier to a generalized Hamilton system. A partial differential equation on the last multiplier of the system is established. The last multiplier can be found by the equation. If the quantity of integrals of the system is sufficient, the solution of the system can be found by the last multiplier. 相似文献
162.
163.
164.
Simon Graßl Clémence Hamze Thaddäus J. Koller Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3752-3755
(Hetero)aryl, benzylic, and alkyl zinc halides were thiolated with N-thiophthalimides at 25 °C within 1 h in the presence of 5–10 % Cu(OAc)2 ⋅ H2O to furnish the corresponding polyfunctionalized thioethers in good yields. This electrophilic thiolation was extended to the introduction of trifluoromethylthio (SCF3), thiocyanate (SCN), and selenophenyl (SePh) groups. The utility of this method was shown in a seven-step synthesis of a potent cathepsin D inhibitor in 34 % overall yield. 相似文献
165.
Journal of Solid State Electrochemistry - The effects of chemisorbed sulfate on the spatiotemporal dynamics of Na2S in strongly alkaline solutions were investigated via electrochemical measurements... 相似文献
166.
Zhang Yi Huang Peng Long Mei Liu Song Yang Huaming Yuan Shuwen Chang Shi 《中国科学:化学(英文版)》2019,62(1):58-61
An innovative cancer therapy strategy regarding the interface engineering of kaolinite has been designed. The exposed silanol group facilitates more guest species with high dispersion on the supports. Mn_3O_4 magnetic nanoparticles are uniformly distributed on external surfaces of the Kaolin_(C12N)with the Al–O–Mn bond for the detection of the tumor microenvironment by T1-MRI; Doxorubicin(DOX) are loaded in the interlayer space with the electrostatic interaction for chemo-treating; and KI is coated on the outer layer of the nanocomposites based on the electrostatic interaction for thyroid cancer targeting. The synergetic effects and the treatment mechanism enhanced by the interface engineering, KI@DOX-Mn_3O_4-Kaolin_(C12N)can cause remarkably low cell viability(57%, 200 μg/mL), tumor shrinking(75%, 20 μg/kg), and accumulation into the tumor tissues. The novel kaolinite based drug delivery system is expected to incorporate imaging diagnosis, targeted therapy and drug delivery into one single system for postoperative residual thyroid cancer treatment and observation for metastasis of focal area. 相似文献
167.
Fei Zhang GaoShan Huang XiaoFei Nie Xin Cao Zhe Ma Fei Ding ZengFeng Di HongLou Zhen YongFeng Mei 《Physics letters. A》2019,383(24):2938-2942
In this study, we investigate the modulation of energy band in 3D self-assembled nanomembranes containing GaAs/Al0.26Ga0.74As quantum wells (QWs). Photoluminescence (PL) characterizations demonstrate that the self-assembled structures have different optical transition properties and the modulation of the energy band is thus realized. Detailed spectral analyses disclose that the small strain change in structures with different curvatures cannot cause remarkable change in energy bands in Al0.26Ga0.74As layer. On the other hand, the optical transitions of GaAs QW layer is influenced by the strain evolution in term of light emission intensity. We also find the first order Stark effect in rolled-up nanomembrane with diameter of 150 μm, which is closely connected with the coupling effect between the deformation potential and the piezoelectric potential. Our work may pave a way for the fabrication of high performance rolled-QW infrared photo-detectors. 相似文献
168.
169.
170.