全文获取类型
收费全文 | 58127篇 |
免费 | 5824篇 |
国内免费 | 9302篇 |
专业分类
化学 | 18673篇 |
晶体学 | 851篇 |
力学 | 1574篇 |
综合类 | 579篇 |
数学 | 3136篇 |
物理学 | 11196篇 |
综合类 | 37244篇 |
出版年
2024年 | 204篇 |
2023年 | 651篇 |
2022年 | 1523篇 |
2021年 | 1768篇 |
2020年 | 1650篇 |
2019年 | 1471篇 |
2018年 | 1357篇 |
2017年 | 1700篇 |
2016年 | 1798篇 |
2015年 | 2546篇 |
2014年 | 3434篇 |
2013年 | 4034篇 |
2012年 | 4356篇 |
2011年 | 4571篇 |
2010年 | 4454篇 |
2009年 | 4619篇 |
2008年 | 4902篇 |
2007年 | 4906篇 |
2006年 | 4403篇 |
2005年 | 3640篇 |
2004年 | 2827篇 |
2003年 | 2019篇 |
2002年 | 2169篇 |
2001年 | 1948篇 |
2000年 | 1869篇 |
1999年 | 1053篇 |
1998年 | 507篇 |
1997年 | 387篇 |
1996年 | 388篇 |
1995年 | 296篇 |
1994年 | 280篇 |
1993年 | 270篇 |
1992年 | 230篇 |
1991年 | 174篇 |
1990年 | 176篇 |
1989年 | 155篇 |
1988年 | 131篇 |
1987年 | 80篇 |
1986年 | 64篇 |
1985年 | 40篇 |
1984年 | 30篇 |
1983年 | 28篇 |
1982年 | 25篇 |
1981年 | 26篇 |
1980年 | 21篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1965年 | 11篇 |
1959年 | 7篇 |
1955年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Recently, thioredoxin reductase as a target for treatment of tumors has attracted the attention of scientists. 1,2‐[Bis(1,2‐benzisoselenazolone‐3(2 H)‐ketone)]ethane (ethaselen, BBSKE, PCT: CN02/00412), designed and synthesized previously, is an effective thioredoxin reductase inhibitor; presently it is in phase II clinical trials, targeting gastric cancer, lung cancer and colon cancer. To seek more novel and effective anticancer drugs, we have developed many selenazole‐based compounds. Evaluation of the thioredoxin reductase inhibitory effect and investigation of the mechanism of anticancer drugs require abundant thioredoxin reductase, but since commercial thioredoxin reductase is expensive its use is often limited. Therefore, the preparation of thioredoxin reductase is necessary. Base on the above investigation, in this work we have prepared thioredoxin reductase and evaluated selenazole‐based compounds, and found that 44 compounds have high inhibitory effect on thioredoxin reductase with IC50 < 10 µ m , of which 16 compounds have IC50 values below 1 µ m . This is helpful in investigating and elucidating the mechanism of this kind of compound. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
122.
Zhimei Wei Quanchao Zhang Lihua Wang Minle Peng Xiaojun Wang Shengru long Jie Yang 《Journal of Polymer Science.Polymer Physics》2012,50(20):1414-1420
The focus of this work is the preparation of aramid nanofibers via electrospinning technology and the study of their adsorption properties. In this article, aramid nanofibers were prepared by electrospinning aramid fibers solution with the addition of lithium chloride (LiCl). It showed a good adsorption capacity when methylene blue (MB) was used as the model target. There were much larger adsorption amounts and faster kinetics of uptaking target species of electrospun aramid nanofibers to MB than that of electrospun polyethersulfone (PES) nanofibers. Compared with activated carbon, aramid nanofibers also have a much faster adsorption rate to MB. Aramid nanofibers were subsequently used to effectively remove endocrine disruptors such as bisphenol A (BPA), phenol (Phe), and p‐hydroquinone (BPhe) from their aqueous solutions. Additionally, molecule imprinted technology enhances aramid nanofibers with much higher adsorption amounts and special adsorption property for endocrine disruptors. These results showed that aramid nanofibers have the potential to be used in environmental applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
123.
本文通过对菏泽学院、潍坊学院、德州学院、滨州学院等高校部分学生参加体育锻炼运动损伤进行调查分析,目的是为了更好的使大学生身心健康得到全面发展,强调科学体育锻炼的重要性。 相似文献
124.
125.
126.
127.
A state space model is described, the time response of ferrite loaded cavity is proposed and a new digital measuring method devised.
Results of actual measurement on model cavity are given. On these bases the stability of stationary state of bias autotuning system to fast external perturbation is discussed. 相似文献
Results of actual measurement on model cavity are given. On these bases the stability of stationary state of bias autotuning system to fast external perturbation is discussed. 相似文献
128.
129.
本文利用密度泛函理论,研究剪切形变下掺杂改性及不同类型缺陷对MoS2电子结构的影响。发现:剪切形变下,MoS2+P体系为相对最稳定的结构,掺杂改性相较于缺陷对模型稳定性影响更小;模型MoS2+P+Se中P-Mo键易形成共价键,而其中的Se-Mo键和MoS2+P-Mo-S模型中的P-Mo键,易形成离子键;掺杂使MoS2模型能隙变大,而缺陷使能隙减小,且S和Mo原子共缺陷的模型带隙为0;缺陷相较于掺杂改性模型,更能使Mo原子周围增加电荷聚集度,带隙值更低,更能影响或调控模型的电子结构。 相似文献
130.