全文获取类型
收费全文 | 196934篇 |
免费 | 2376篇 |
国内免费 | 661篇 |
专业分类
化学 | 109653篇 |
晶体学 | 2419篇 |
力学 | 8040篇 |
综合类 | 5篇 |
数学 | 18925篇 |
物理学 | 60929篇 |
出版年
2016年 | 2522篇 |
2015年 | 1821篇 |
2014年 | 2583篇 |
2013年 | 8204篇 |
2012年 | 5530篇 |
2011年 | 6895篇 |
2010年 | 4609篇 |
2009年 | 4512篇 |
2008年 | 6177篇 |
2007年 | 6357篇 |
2006年 | 6069篇 |
2005年 | 5521篇 |
2004年 | 5060篇 |
2003年 | 4524篇 |
2002年 | 4423篇 |
2001年 | 5821篇 |
2000年 | 4422篇 |
1999年 | 3546篇 |
1998年 | 2771篇 |
1997年 | 2800篇 |
1996年 | 2754篇 |
1995年 | 2545篇 |
1994年 | 2421篇 |
1993年 | 2304篇 |
1992年 | 2702篇 |
1991年 | 2570篇 |
1990年 | 2519篇 |
1989年 | 2563篇 |
1988年 | 2501篇 |
1987年 | 2496篇 |
1986年 | 2317篇 |
1985年 | 3206篇 |
1984年 | 3239篇 |
1983年 | 2633篇 |
1982年 | 2827篇 |
1981年 | 2785篇 |
1980年 | 2668篇 |
1979年 | 2837篇 |
1978年 | 3100篇 |
1977年 | 2911篇 |
1976年 | 2859篇 |
1975年 | 2707篇 |
1974年 | 2655篇 |
1973年 | 2685篇 |
1972年 | 1724篇 |
1969年 | 1455篇 |
1968年 | 1927篇 |
1967年 | 2126篇 |
1966年 | 1921篇 |
1965年 | 1497篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
31.
32.
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
33.
Ahmed Waqar Chowdhury Z. Z. Kazi S. N. Johan MR. Akram Naveed Oon C. S. Abdelrazek Ali H. 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1517-1534
Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers... 相似文献
34.
Journal of Thermal Analysis and Calorimetry - Low productivity of single-slope solar still is the main barrier for its worldwide usability. An attempt has been conducted to enhance the distillate... 相似文献
35.
Multi-sensor data fusion is an evolving technology whereby data from multiple sensor inputs are processed and combined. The data derived from multiple sensors can, however, be uncertain, imperfect, and conflicting. The present study is undertaken to help contribute to the continuous search for viable approaches to overcome the problems associated with data conflict and imperfection. Sensor readings, represented by belief functions, have to be fused according to their corresponding weights. Previous studies have often estimated the weights of sensor readings based on a single criterion. Mono-criteria approaches for the assessment of sensor reading weights are, however, often unreliable and inadequate for the reflection of reality. Accordingly, this work opts for the use of a multi-criteria decision aid. A modified Analytical Hierarchy Process (AHP) that incorporates several criteria is proposed to determine the weights of a sensor reading set. The approach relies on the automation of pairwise comparisons to eliminate subjectivity and reduce inconsistency. It assesses the weight of each sensor reading, and fuses the weighed readings obtained using a modified average combination rule. The efficiency of this approach is evaluated in a target recognition context. Several tests, sensitivity analysis, and comparisons with other approaches available in the literature are described. 相似文献
36.
Indermeet Kohli Taylor L. Braunberger Amanda F. Nahhas Fatima N. Mirza Mohsen Mokhtari Alexis B. Lyons Nikiforos Kollias Eduardo Ruvolo Henry W. Lim Iltefat H. Hamzavi 《Photochemistry and photobiology》2020,96(1):208-214
Human skin is exposed to visible light (VL; 400–700 nm) and long-wavelength ultraviolet A1 (UVA1) radiation (370–400 nm) after the application of organic broad-spectrum sunscreens. The biologic effects of these wavelengths have been demonstrated; however, a dose–response has not been investigated. Ten subjects with Fitzpatrick skin phototype IV-VI were enrolled. Subjects were irradiated with 2 light sources (80–480 J cm−2): one comprising VL with less than 0.5% UVA1 (VL+UVA1) and the other pure VL. Skin responses were evaluated for 2 weeks using clinical and spectroscopic assessments. 4-mm punch biopsies were obtained from nonirradiated skin and sites irradiated with 480 J cm−2 of VL+UVA1 and pure VL 24 h after irradiation. Clinical and spectroscopic assessments demonstrated a robust response at VL+UVA1 sites compared with pure VL. Histology findings demonstrated a statistically significant increase in the marker of inflammation (P < 0.05) and proliferation (P < 0.05) at the irradiated sites compared with nonirradiated control. Threshold doses of VL+UVA1 resulting in biologic responses were calculated. Results indicate that approximately 2 h of sun exposure, which equates to VL+UVA1 dose (~400 J cm−2), is capable of inducing inflammation, immediate erythema and delayed tanning. These findings reinforce the need of photoprotection beyond the UV range. 相似文献
37.
38.
39.
40.