全文获取类型
收费全文 | 22891篇 |
免费 | 3579篇 |
国内免费 | 3424篇 |
专业分类
化学 | 17076篇 |
晶体学 | 404篇 |
力学 | 1358篇 |
综合类 | 324篇 |
数学 | 2834篇 |
物理学 | 7898篇 |
出版年
2024年 | 30篇 |
2023年 | 331篇 |
2022年 | 591篇 |
2021年 | 696篇 |
2020年 | 767篇 |
2019年 | 841篇 |
2018年 | 708篇 |
2017年 | 769篇 |
2016年 | 1084篇 |
2015年 | 1089篇 |
2014年 | 1332篇 |
2013年 | 1727篇 |
2012年 | 2044篇 |
2011年 | 2099篇 |
2010年 | 1533篇 |
2009年 | 1524篇 |
2008年 | 1663篇 |
2007年 | 1487篇 |
2006年 | 1394篇 |
2005年 | 1108篇 |
2004年 | 1023篇 |
2003年 | 889篇 |
2002年 | 1013篇 |
2001年 | 859篇 |
2000年 | 572篇 |
1999年 | 524篇 |
1998年 | 346篇 |
1997年 | 241篇 |
1996年 | 250篇 |
1995年 | 198篇 |
1994年 | 185篇 |
1993年 | 175篇 |
1992年 | 122篇 |
1991年 | 119篇 |
1990年 | 86篇 |
1989年 | 91篇 |
1988年 | 56篇 |
1987年 | 53篇 |
1986年 | 52篇 |
1985年 | 48篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 16篇 |
1956年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
Journal of Thermal Analysis and Calorimetry - The fire behavior of one flame-retardant PVC cable used as building wire is investigated in this work. Bench scale tests were performed using a cone... 相似文献
14.
Nováková Kateřina Hrdlička Vojtěch Navrátil Tomáš Vyskočil Vlastimil Barek Jiří 《Monatshefte für Chemie / Chemical Monthly》2015,146(5):761-769
Monatshefte für Chemie - Chemical Monthly - The voltammetric behavior of 5-nitroindazole was investigated at polished (p-AgSAE) and at mercury meniscus-modified (m-AgSAE) silver solid amalgam... 相似文献
15.
Ionics - This study aims to explore the potential merits of palladium oxide sensing electrode. PdO is applied on a solid-state potentiometric sensor on an yttria-stabilized zirconia (YSZ)... 相似文献
16.
An N. Le Ruiqi Liang Xiaoyu Ji Xiaowei Fu Mingjiang Zhong 《Journal of polymer science. Part A, Polymer chemistry》2021,59(21):2571-2580
The random copolymerization of norbornene-functionalized macromonomers was explored as a method of synthesizing mixed-graft block copolymers (mGBCPs). The copolymerization kinetics of a model system of polystyrene (PS) and poly(lactic acid) (PLA) macromonomers was first analyzed, revealing a gradient composition of side chains along the mGBCP backbone. The phase separation behavior of mGBCPs with PS and PLA side chains of various backbone lengths and side chain molar ratios was investigated, and increasing the backbone length was found to stabilize the phase-separated nanostructures. The graft architecture was also demonstrated to improve the processability of the mGBCP, compared to a linear counterpart. Investigations of mGBCPs comprised of polydimethylsiloxane and poly(ethylene oxide) side chains exemplified the diverse self-assembled morphologies, including a Frank-Kasper A15 phase, that can be obtained with mGBCPs synthesized by random copolymerization of macromonomers. Lastly, a ternary mGBCP was synthesized by the copolymerization of three macromonomers. 相似文献
17.
18.
19.
Numerical Algorithms - A singularly perturbed Volterra integro-differential equation with an integrable singularity in the integral term is considered. The upwind difference method is used to... 相似文献
20.
Metabolic profiles of dioscin in rats revealed by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry
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)
He Zhu Jin‐Di Xu Qian Mao Hong Shen Ming Kong Jian‐Ping Chen Song‐Lin Li 《Biomedical chromatography : BMC》2015,29(9):1415-1421
Dioscin (DIS), one of the most abundant bioactive steroidal saponins in Dioscorea sp., is used as a complementary medicine to treat coronary disease and angina pectoris in China. Although the pharmacological activities and pharmacokinetics of DIS have been well demonstrated, information regarding the final metabolic fates is very limited. This study investigated the in vivo metabolic profiles of DIS after oral administration by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry method. The structures of the metabolites were identified and tentatively characterized by means of comparing the molecular mass, retention time and fragmentation pattern of the analytes with those of the parent compound. A total of eight metabolites, including seven phase I and one phase II metabolites, were detected and tentatively identified for the first time. Oxidation, deglycosylation and glucuronidation were found to be the major metabolic processes of the compound in rats. In addition, a possible metabolic pathway on the biotransformation of DIS in vivo was proposed. This study provides valuable and new information on the metabolism of DIS, which will be helpful for further understanding its mechanism of action. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献