全文获取类型
收费全文 | 15471篇 |
免费 | 2564篇 |
国内免费 | 1865篇 |
专业分类
化学 | 11584篇 |
晶体学 | 184篇 |
力学 | 787篇 |
综合类 | 97篇 |
数学 | 1382篇 |
物理学 | 5866篇 |
出版年
2024年 | 53篇 |
2023年 | 277篇 |
2022年 | 519篇 |
2021年 | 575篇 |
2020年 | 653篇 |
2019年 | 646篇 |
2018年 | 572篇 |
2017年 | 477篇 |
2016年 | 768篇 |
2015年 | 721篇 |
2014年 | 865篇 |
2013年 | 1208篇 |
2012年 | 1380篇 |
2011年 | 1350篇 |
2010年 | 932篇 |
2009年 | 935篇 |
2008年 | 1045篇 |
2007年 | 944篇 |
2006年 | 849篇 |
2005年 | 757篇 |
2004年 | 616篇 |
2003年 | 523篇 |
2002年 | 570篇 |
2001年 | 396篇 |
2000年 | 291篇 |
1999年 | 303篇 |
1998年 | 250篇 |
1997年 | 221篇 |
1996年 | 200篇 |
1995年 | 164篇 |
1994年 | 140篇 |
1993年 | 109篇 |
1992年 | 107篇 |
1991年 | 102篇 |
1990年 | 69篇 |
1989年 | 57篇 |
1988年 | 39篇 |
1987年 | 30篇 |
1986年 | 34篇 |
1985年 | 35篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 9篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1936年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Jinkun Sun Yingjian Liu Jiayi Huang Jiatian Li Mengmeng Chen Xiaoyu Hu Yatao Liu Run Wang Yanan Shen Jingjing Li Xuecheng Chen Dong Qian Baigang An Zunfeng Liu 《Journal of Energy Chemistry》2021,(12):594-603
Increasing mechanical flexibility without sacrificing electrochemical performance of the electrode mate-rial is highly desired in the design of flexible electro... 相似文献
53.
54.
55.
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
56.
Xinzhi Chen Shaodong Zhou Yuehan Chen Zehan Dong Yeyu Gao Chao Qian Chaohong He 《Research on Chemical Intermediates》2012,38(9):2255-2269
Alcoholate was utilized in catalytic transfer hydrogenation of unsaturated nitrogen compounds. In the reduction of nitro compounds, oximes and imines, alkoxide was used as the promoter, with alcohol as the hydrogen source, while in the reduction of nitriles, alkoxide was used as the hydrogen source. 相似文献
57.
D形光纤Bragg光栅弯曲灵敏度的理论和实验研究 总被引:1,自引:1,他引:1
用材料力学理论分析了D形光纤Bragg光栅(D-shaped fiber Bragg grating,D-FBG)以及常规光纤Bragg光栅由弯曲引起的轴向应变,得到了光栅Bragg波长漂移的弯曲敏感特性.实验结果和理论计算结果基本相符.与常规FBG相比,该D-FBG的弯曲灵敏度要高近80倍.因此D-FBG可以直接应用于弯曲形变的测量,以及间接应用于压力、加速度等物理量的测量.理论分析和实验结果对采用该类型光纤光栅的器件和传感系统的设计具有参考意义. 相似文献
58.
59.
The temperature dependence of the quadrupole interaction of111Cd in the In0.95 Ag0.045 Ga0.005 alloy is determined by the time differential perturbed angular correlation method from 77 to 422 K. The electric field gradients
produced by the lattice are derived. The temperature dependence of the electric field gradient is found to follow theT
3/2 law observed in In between 77 K and room temperature and to deviate from it at higher temperatures. The widths of the electric
field gradient distribution are 0.1147(259), 0.0924(340), 0.4954(601) and 1.344(175) at 77, 298, 373 and 422 K, respectively.
This illustrates that the alloy is well ordered at 77 and 298 K and that it becomes less ordered at 373 and 422 K. 相似文献
60.
研究了二氯三烯丙基硫脲合镉(ATCC),二氯三烯丙基硫脲合汞(ATMC)和二溴三烯丙基硫脲合镉(ATCB)三种晶体的结构特点.首次报道了ATMC和ATCB晶体的非线性光学系数及倍频性能;文中分析比较了三种晶体的非线性光学性能;讨论了晶体结构与性能的关系,为探索高效非线性光学新材料提供依据. 相似文献