全文获取类型
收费全文 | 101708篇 |
免费 | 2287篇 |
国内免费 | 2069篇 |
专业分类
化学 | 31806篇 |
晶体学 | 923篇 |
力学 | 7523篇 |
综合类 | 95篇 |
数学 | 33214篇 |
物理学 | 19271篇 |
无线电 | 13232篇 |
出版年
2023年 | 292篇 |
2022年 | 294篇 |
2021年 | 435篇 |
2020年 | 485篇 |
2019年 | 411篇 |
2018年 | 12095篇 |
2017年 | 11723篇 |
2016年 | 7403篇 |
2015年 | 1425篇 |
2014年 | 1045篇 |
2013年 | 1282篇 |
2012年 | 5202篇 |
2011年 | 12674篇 |
2010年 | 7573篇 |
2009年 | 7590篇 |
2008年 | 8069篇 |
2007年 | 10465篇 |
2006年 | 1086篇 |
2005年 | 2337篇 |
2004年 | 2318篇 |
2003年 | 2658篇 |
2002年 | 1519篇 |
2001年 | 663篇 |
2000年 | 658篇 |
1999年 | 566篇 |
1998年 | 631篇 |
1997年 | 507篇 |
1996年 | 564篇 |
1995年 | 434篇 |
1994年 | 393篇 |
1993年 | 305篇 |
1992年 | 268篇 |
1991年 | 230篇 |
1990年 | 225篇 |
1989年 | 158篇 |
1988年 | 153篇 |
1987年 | 160篇 |
1986年 | 151篇 |
1985年 | 125篇 |
1984年 | 101篇 |
1983年 | 74篇 |
1982年 | 79篇 |
1981年 | 69篇 |
1980年 | 68篇 |
1979年 | 60篇 |
1978年 | 50篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
Development of an LC‐MS/MS method for determining the pharmacokinetics of clonidine following oral administration of Zhenju antihypertensive compound
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jing Qin Limin Wang Lihong Wu Jun Chen Teng Shen Yongji Li Limei Han Jianxin Wang 《Biomedical chromatography : BMC》2015,29(7):1068-1075
Zhenju antihypertensive compound (ZJAHC) is a combined Chinese–Western medicine formula including clonidine (CLO), hydrochlorothiazide (HCT), rutin, Chrysanthemum indicum extract and pearl powder. Compared with CLO preparations, ZJAHC shows improved activities and decreased adverse effects. It is believed that the side effects of CLO are caused by its high peak plasma concentration. Hence, study of the influence of ZJAHC on the pharmacokinetic behaviors of clonidine seems essential. In present study, the plasma concentrations of CLO were determined with a liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method. The MS/MS transitions monitored for clonidine and internal standard were 230.2 → 213.1 and 152.2 → 110.2, respectively. The analyte was quantified in a single run within 3 min. The pharmacokinetic study showed that the area under the plasma concentration–time curve of CLO in ZJAHC (60 µg/kg CLO) was similar to that of CLO‐HCT‐high (120 µg/kg CLO) but the peak concentration was much lower than that in CLO‐HCT‐high. ZJAHC could enhance the bioavailability without greatly increasing peak concentration of clonidine. This comprehensive effect of enhancing the bioavailability and avoiding the high peak plasma concentration for CLO might mainly result from the co‐contribution of Western medicine and traditional Chinese medicine (TCM), while the effect of TCM was stronger than that of Western medicine. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
34.
Journal of Global Optimization - In this paper, we propose a novel algorithm that is based on quadratic-piecewise-linear approximations of DC functions to solve nonnegative sparsity-constrained... 相似文献
35.
36.
Yang Aiying Wang Ziyu Zhang Zhaoyi Chen Zhangyuan Wu Deming 《电子科学学刊(英文版)》2003,20(6):461-466
A 10Gbit/s recirculating system is configured with Chirped Fiber Bragg Grating (CFBG) for the dispersion compensation. For the first time, the transmission distance in the loop reaches 1000km with bit error rate of 10-9. The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4×167.1km ) in the loop with the power penalty fluctuation below 1.0dB. Thus the group delay ripple should be reduced to allow for the wavelength drift of±5GHz. At the end of this letter, the principles are given for designing long haul recirculating systems with dispersion compensation CFBG. 相似文献
37.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
38.
39.
40.