全文获取类型
收费全文 | 83584篇 |
免费 | 1421篇 |
国内免费 | 1170篇 |
专业分类
化学 | 28413篇 |
晶体学 | 891篇 |
力学 | 7082篇 |
综合类 | 44篇 |
数学 | 32592篇 |
物理学 | 17153篇 |
出版年
2023年 | 135篇 |
2022年 | 191篇 |
2021年 | 244篇 |
2020年 | 343篇 |
2019年 | 298篇 |
2018年 | 10651篇 |
2017年 | 10495篇 |
2016年 | 6375篇 |
2015年 | 1205篇 |
2014年 | 637篇 |
2013年 | 798篇 |
2012年 | 4329篇 |
2011年 | 11026篇 |
2010年 | 6004篇 |
2009年 | 6398篇 |
2008年 | 6960篇 |
2007年 | 9061篇 |
2006年 | 528篇 |
2005年 | 1573篇 |
2004年 | 1738篇 |
2003年 | 2122篇 |
2002年 | 1186篇 |
2001年 | 351篇 |
2000年 | 392篇 |
1999年 | 254篇 |
1998年 | 229篇 |
1997年 | 190篇 |
1996年 | 237篇 |
1995年 | 150篇 |
1994年 | 85篇 |
1993年 | 122篇 |
1992年 | 74篇 |
1991年 | 78篇 |
1990年 | 62篇 |
1989年 | 71篇 |
1988年 | 77篇 |
1987年 | 64篇 |
1986年 | 74篇 |
1985年 | 65篇 |
1984年 | 54篇 |
1983年 | 44篇 |
1982年 | 55篇 |
1981年 | 46篇 |
1980年 | 54篇 |
1979年 | 58篇 |
1978年 | 44篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 42篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
Kai Cheng Xiao-Shuai Zhang Jie An Cheng Li Ruo-Yun Zhang Run Ye Prof. Dr. Bang-Jiao Ye Prof. Dr. Bo Liu Prof. Dr. Yuan-Di Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(31):7553-7560
Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag2S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag2S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag2S had more opportunities to react with surrounding O2, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag2S and PDA-Ag2S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag2S showed distinctly better therapeutic effects than Ag2S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag2S quantum dots, which extended and enhanced the regulatory effect originating from PDA. 相似文献
2.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
3.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
4.
5.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
6.
7.
8.
9.
采用粉末冶金法向铜基金属结合剂中引入玻璃料,结合材料电子万能试验机、洛氏硬度仪、SEM等检测方法,研究了玻璃料加入对铜基金属结合剂及金刚石磨具的影响.结果表明,随着玻璃料含量的增加,铜基结合剂的抗折强度和抗冲击强度呈下降的趋势,其硬度呈逐渐上升趋势,硬脆相的引入提高了铜基金属结合剂的自锐性;玻璃相和金属相之间结合紧密,两相之间化学元素在界面处发生相互扩散;玻璃料的加入使结合剂对磨料的包裹更加紧密,大大提高了结合剂对金刚石的把持力,有利于增加金刚石磨具寿命及加工效率. 相似文献
10.
Journal of Thermal Analysis and Calorimetry - A complete analysis of the thermal process about melamine was presented, in which different methods were applied to determine the characteristic of the... 相似文献