全文获取类型
收费全文 | 8672篇 |
免费 | 1705篇 |
国内免费 | 1046篇 |
专业分类
化学 | 6542篇 |
晶体学 | 96篇 |
力学 | 420篇 |
综合类 | 96篇 |
数学 | 864篇 |
物理学 | 3405篇 |
出版年
2024年 | 24篇 |
2023年 | 185篇 |
2022年 | 276篇 |
2021年 | 338篇 |
2020年 | 418篇 |
2019年 | 464篇 |
2018年 | 368篇 |
2017年 | 331篇 |
2016年 | 493篇 |
2015年 | 479篇 |
2014年 | 564篇 |
2013年 | 685篇 |
2012年 | 867篇 |
2011年 | 831篇 |
2010年 | 614篇 |
2009年 | 513篇 |
2008年 | 582篇 |
2007年 | 548篇 |
2006年 | 435篇 |
2005年 | 343篇 |
2004年 | 248篇 |
2003年 | 228篇 |
2002年 | 269篇 |
2001年 | 249篇 |
2000年 | 140篇 |
1999年 | 181篇 |
1998年 | 125篇 |
1997年 | 88篇 |
1996年 | 84篇 |
1995年 | 61篇 |
1994年 | 62篇 |
1993年 | 63篇 |
1992年 | 50篇 |
1991年 | 50篇 |
1990年 | 41篇 |
1989年 | 35篇 |
1988年 | 23篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1959年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
Dr. Hong Wang Jia Jia Prof. Pengfei Song Dr. Qiang Wang Dr. Debao Li Prof. Shixiong Min Dr. Chenxi Qian Dr. Lu Wang Young Feng Li Chun Ma Prof. Tom Wu Prof. Jiayin Yuan Prof. Markus Antonietti Prof. Geoffrey A. Ozin 《Angewandte Chemie (International ed. in English)》2017,56(27):7847-7852
Herein we introduce a straightforward, low cost, scalable, and technologically relevant method to manufacture an all-carbon, electroactive, nitrogen-doped nanoporous-carbon/carbon-nanotube composite membrane, dubbed “HNCM/CNT”. The membrane is demonstrated to function as a binder-free, high-performance gas diffusion electrode for the electrocatalytic reduction of CO2 to formate. The Faradaic efficiency (FE) for the production of formate is 81 %. Furthermore, the robust structural and electrochemical properties of the membrane endow it with excellent long-term stability. 相似文献
932.
Wei Hu Bin Xie Ying Wang Jia‐qing Xie Xiang‐guang Meng Juan Du 《Journal of Dispersion Science and Technology》2013,34(6):860-868
Two transitional metal ion macrocyclic Schiff base complexes, NiL and CuL were synthesized and characterized, and the metallomicelles made up of the nickel(II) and copper(II) complexes and surfactants(LSS, Brij35, CTAB), as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP). The analysis of specific absorption spectrums of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Ni(II) or Cu(II) complexes, have formed in the reaction processes of the PNPP catalytic hydrolysis. In this, based on the analytic result of specific absorption spectrum, the mechanism of PNPP catalytic hydrolysis has been proposed; a kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis has been established on the foundation of the mechanism proposed; the acid effect of reaction system, structure effect of the complexes, effect of temperature and effects of micelle on the rate of PNPP hydrolysis catalyzed by the complexes also have been discussed. 相似文献
933.
Uniformity nanosheets of CuO were prepared by a mild hydrothermal synthesis method. Phase analysis was carried out using x-ray diffraction (XRD) and the result confirmed the CuO nanosheets as a single phase. The field-emission scanning electron microscopy (FE-SEM) was used to observe the morphology of CuO nanosheets while the gas sensing properties of these unique CuO nanosheets were tested at a static state system. The results show that the CuO has uniformity nanosheets, and the gas sensing property show that the CuO nanosheets gas sensor has a stable gas response and the same gas sensitivity trend to tested gases. This method may be suitable for larger-scale production of these CuO nanosheets for practical applications. 相似文献
934.
935.
Xiaodong Jia Chang Qing Congde Huo Fangfang Peng Xicun Wang 《Tetrahedron letters》2012,53(52):7140-7142
A domino process between iminoethyl glyoxylate and N-vinylamides was achieved under the catalytic radical cation salt induced conditions, producing a series of quinoline-2-carboxylates. N-Vinylamides were involved as an acetylene equivalent. A possible mechanism was proposed to rationalize the formation of the products. 相似文献
936.
937.
Yue‐Feng Bi Lu Jia She‐Po Shi Xiao‐Li Sun Yuan‐Yuan Chen Yang‐Bing Zhang 《Helvetica chimica acta》2010,93(10):1953-1959
Two new guaianolides (=guaianolactones), chrysanthguaianolactone A and B ( 1 and 2 , resp.), and one new eudesmane sesquiterpene, chrysanthemdiol A ( 6 ), together with seven known sesquiterpenes were isolated from the flowers of Chrysanthemum indicum L. Their structures were elucidated on the basis of spectroscopic evidence. 相似文献
938.
In the paper,an experiment investigation was conducted for one-and two-degree of freedom vortex-induced vibration(VIV) of a horizontally-oriented cylinder with diameter of 11 cm and length of 120 cm.In the experiment,the spring constants in the cross-flow and in-line flow directions were regulated to change the natural vibration frequency of the model system.It was found that,in the one-degree of freedom VIV experiment,a "double peak" phenomenon was observed in its amplitude within the range of the reduced velocities tested,moreover,a "2T" wake appeared in the vicinity of the second peak.In the two-degree of freedom VIV experiment,the trajectory of cylinder exhibited a reverse "C" shape,i.e.,a "new moon" shape.Through analysis of these data,it appears that,besides the non-dimensional in-line and cross-flow natural vibration frequency ratios,the absolute value of the natural vibration frequency of cylinder is also one of the important parameters affecting its VIV behavior. 相似文献
939.
940.