全文获取类型
收费全文 | 38346篇 |
免费 | 1165篇 |
国内免费 | 105篇 |
专业分类
化学 | 23489篇 |
晶体学 | 222篇 |
力学 | 981篇 |
综合类 | 9篇 |
数学 | 5623篇 |
物理学 | 9292篇 |
出版年
2023年 | 228篇 |
2022年 | 309篇 |
2021年 | 514篇 |
2020年 | 564篇 |
2019年 | 528篇 |
2018年 | 579篇 |
2017年 | 536篇 |
2016年 | 1051篇 |
2015年 | 967篇 |
2014年 | 1074篇 |
2013年 | 1919篇 |
2012年 | 2336篇 |
2011年 | 2456篇 |
2010年 | 1398篇 |
2009年 | 1209篇 |
2008年 | 2122篇 |
2007年 | 2075篇 |
2006年 | 1952篇 |
2005年 | 2300篇 |
2004年 | 2183篇 |
2003年 | 1621篇 |
2002年 | 1223篇 |
2001年 | 807篇 |
2000年 | 749篇 |
1999年 | 467篇 |
1998年 | 383篇 |
1997年 | 376篇 |
1996年 | 483篇 |
1995年 | 394篇 |
1994年 | 374篇 |
1993年 | 412篇 |
1992年 | 392篇 |
1991年 | 325篇 |
1990年 | 274篇 |
1989年 | 246篇 |
1988年 | 226篇 |
1987年 | 223篇 |
1986年 | 236篇 |
1985年 | 313篇 |
1984年 | 291篇 |
1983年 | 229篇 |
1982年 | 254篇 |
1981年 | 254篇 |
1980年 | 236篇 |
1979年 | 205篇 |
1978年 | 233篇 |
1977年 | 189篇 |
1976年 | 183篇 |
1975年 | 161篇 |
1974年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
Mathieu Boiret Anna de Juan Nathalie Gorretta Yves-Michel Ginot Jean-Michel Roger 《Analytica chimica acta》2015
Raman chemical imaging provides chemical and spatial information about pharmaceutical drug product. By using resolution methods on acquired spectra, the objective is to calculate pure spectra and distribution maps of image compounds. With multivariate curve resolution-alternating least squares, constraints are used to improve the performance of the resolution and to decrease the ambiguity linked to the final solution. Non negativity and spatial local rank constraints have been identified as the most powerful constraints to be used. 相似文献
14.
The Effect of the Spacer of Bis(biurea) Ligands on the Structure of A2L3‐type (A=anion) Phosphate Complexes 下载免费PDF全文
Prof. Biao Wu Dr. Shaoguang Li Prof. Yibo Lei Prof. Huaiming Hu Dr. Nader de Sousa Amadeu Prof. Dr. Christoph Janiak Dr. Jennifer S. Mathieson Dr. De‐Liang Long Prof. Leroy Cronin Prof. Xiao‐Juan Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2588-2593
By tuning the length and rigidity of the spacer of bis(biurea) ligands L, three structural motifs of the A2L3 complexes (A represents anion, here orthophosphate PO43?), namely helicate, mesocate, and mono‐bridged motif, have been assembled by coordination of the ligand to phosphate anion. Crystal structure analysis indicated that in the three complexes, each of the phosphate ions is coordinated by twelve hydrogen bonds from six surrounding urea groups. The anion coordination properties in solution have also been studied. The results further demonstrate the coordination behavior of phosphate ion, which shows strong tendency for coordination saturation and geometrical preference, thus allowing for the assembly of novel anion coordination‐based structures as in transition‐metal complexes. 相似文献
15.
Vsevolod Khikhlovskyi Albert J. J. M. van Breemen Jasper J. Michels René A. J. Janssen Gerwin H. Gelinck Martijn Kemerink 《Journal of Polymer Science.Polymer Physics》2015,53(17):1231-1237
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237 相似文献
16.
17.
18.
19.
José Luis Olloqui-Sariego Juan José Calvente Rafael Andreu 《Current Opinion in Electrochemistry》2021
Three key challenges are stimulating intensive research in the development of productive direct electron transfer mode enzyme electrodes: proper enzyme orientation, high enzyme loading, and full retention of enzyme activity. In this review, we summarize some significant advances that have been reported in the last years on the design of mesoporous and nanostructured electrodes as enzyme scaffolds and of innovative methodologies for wiring enzymes to electrodes. Particular attention is given to investigations on physical factors that determine a favorable enzyme immobilization, to provide rational guidelines for the design of productive enzymatic electrodes. Finally, some emerging trends focused on the spatial organization of either single enzymes or enzyme cascades are also briefly addressed. 相似文献
20.
Active anodes, especially those consisting of metal mixed oxides (MMOs) containing Ru and/or Ir oxides, have been applied in the treatment of wastewater, especially when chloride ions are present. Their characteristics continuously drive the study of applications of these materials, be they in the degradation of different organic molecules, the preparation of new electrode materials and in the association of various processes to increase pollutant removal. Thus, this brief review aims to present some of the recent advances in the application of active anode materials in environmental electrochemistry. Focussing on the 2018–2020 period, it is possible to note many applied studies, using commercially available materials, covering a wide range of target pollutants. Still other studies aim to modify the catalyst surfaces to increase the mineralization capacity, and the use of these anodes in the production of free chlorine species to mediate indirect organic reduction is observed. 相似文献