全文获取类型
收费全文 | 192443篇 |
免费 | 11157篇 |
国内免费 | 7088篇 |
专业分类
化学 | 114370篇 |
晶体学 | 2640篇 |
力学 | 9405篇 |
综合类 | 520篇 |
数学 | 20418篇 |
物理学 | 63335篇 |
出版年
2022年 | 2653篇 |
2021年 | 2861篇 |
2020年 | 3118篇 |
2019年 | 3009篇 |
2018年 | 2782篇 |
2017年 | 2488篇 |
2016年 | 4189篇 |
2015年 | 4035篇 |
2014年 | 4919篇 |
2013年 | 9529篇 |
2012年 | 9091篇 |
2011年 | 10198篇 |
2010年 | 6641篇 |
2009年 | 6390篇 |
2008年 | 7956篇 |
2007年 | 7606篇 |
2006年 | 7404篇 |
2005年 | 6847篇 |
2004年 | 5771篇 |
2003年 | 4947篇 |
2002年 | 4644篇 |
2001年 | 4931篇 |
2000年 | 4020篇 |
1999年 | 3709篇 |
1998年 | 3168篇 |
1997年 | 2989篇 |
1996年 | 2974篇 |
1995年 | 2824篇 |
1994年 | 2522篇 |
1993年 | 2379篇 |
1992年 | 2504篇 |
1991年 | 2377篇 |
1990年 | 2218篇 |
1989年 | 2148篇 |
1988年 | 2040篇 |
1987年 | 2014篇 |
1986年 | 1874篇 |
1985年 | 2428篇 |
1984年 | 2456篇 |
1983年 | 2056篇 |
1982年 | 2341篇 |
1981年 | 2133篇 |
1980年 | 2145篇 |
1979年 | 2102篇 |
1978年 | 2234篇 |
1977年 | 2141篇 |
1976年 | 2160篇 |
1975年 | 2100篇 |
1974年 | 1935篇 |
1973年 | 2148篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
33.
34.
35.
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
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
36.
37.
38.
在氢化丁苯共聚物13C-NMR谱脂肪碳部分谱带归属的基础上,根据各谱带的主要来源,推导出六个二单元浓度的计算公式。计算出二单元、一单元的相对含量,各结构单元的数均序列长度、嵌段含量和其它结构参数。加氢前后的1H-和13C-NMR谱的组成计算结果基本一致。初步探讨了作为粘度指数改进剂的氢化丁苯共聚物微观结构与性能的关系,为合成提供了依据。 相似文献
39.
The interaction of isotactic polypropylene with ethylene propylene diene terpolymer in their blends has been investigated by use of differential scanning calorimetry, dynamic mechanical analysis, wide- and small-angle x-ray scattering, and by investigating the nucleation and kinetics of crystallization of the iPP component under the polarization microscope. It is found, that the dispersion of the EPDM component in the iPP matrix is dependent on blend composition and is maximal at 10% EPDM content. An interface layer between the two components is formed by migration of iPP molecules into the EPDM phase. A model for this interface is proposed. 相似文献
40.