全文获取类型
收费全文 | 5811篇 |
免费 | 690篇 |
国内免费 | 747篇 |
专业分类
化学 | 4380篇 |
晶体学 | 76篇 |
力学 | 274篇 |
综合类 | 77篇 |
数学 | 910篇 |
物理学 | 1531篇 |
出版年
2024年 | 15篇 |
2023年 | 115篇 |
2022年 | 202篇 |
2021年 | 210篇 |
2020年 | 255篇 |
2019年 | 266篇 |
2018年 | 219篇 |
2017年 | 224篇 |
2016年 | 278篇 |
2015年 | 313篇 |
2014年 | 364篇 |
2013年 | 533篇 |
2012年 | 522篇 |
2011年 | 503篇 |
2010年 | 396篇 |
2009年 | 367篇 |
2008年 | 430篇 |
2007年 | 357篇 |
2006年 | 327篇 |
2005年 | 226篇 |
2004年 | 178篇 |
2003年 | 123篇 |
2002年 | 131篇 |
2001年 | 77篇 |
2000年 | 72篇 |
1999年 | 67篇 |
1998年 | 47篇 |
1997年 | 45篇 |
1996年 | 38篇 |
1995年 | 16篇 |
1994年 | 28篇 |
1993年 | 27篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 16篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 16篇 |
1979年 | 10篇 |
1978年 | 18篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1975年 | 9篇 |
排序方式: 共有7248条查询结果,搜索用时 394 毫秒
991.
Simultaneous determination of three major lignans in rat plasma by LC‐MS/MS and its application to a pharmacokinetic study after oral administration of Diphylleia sinensis extract
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)
Weiyan He Rui Li Dan Shi Li Pang Ning Dong Hong Xu Honglei Ji 《Biomedical chromatography : BMC》2014,28(4):463-467
A sensitive and selective liquid chromatography tandem mass spectrometry was developed and validated for the simultaneous determination of three major lignans (podophyllotoxin, epipodophyllotoxin, and 4′‐demethylpodophyllotoxin) in rat plasma using diphenhydramine as the internal standard. The analytes were detected using a triple quadrupole mass spectrometer that was equipped with an electrospray ionization source in the positive ion and selected reaction monitoring modes. The linearity of the calibration curve was good, with coefficients of determination (r2) >0.9914 for all of the analytes. The developed method was successfully applied for the simultaneous determination of the three lignans in rat plasma following oral administration of Diphylleia sinensis extract to rats. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
992.
993.
Fangzhong Hu Xinxin Cheng Zixia Niu Xiaobing Yang Dan Li Lei Wan Junxiao Li Bin Liu Xiaomao Zou Huazheng Yang Bin Li 《Journal of heterocyclic chemistry》2015,52(3):793-801
A series of 3‐phenyl benzo[d][1,2,3]triazin‐4(3H)‐one derivatives were synthesized through the condensation of phenol E and alkyl (alkenyl, alkynyl) chlorides (bromides, iodide) or alkyl chloroacetates or N‐alkyl chloroacetamides using K2CO3 as the acid acceptor in N,N‐dimethylformamide. Phenol E was prepared from starting material, 5‐amino‐2‐chloro‐4‐fluorophenyl ethyl carbonate, in four steps involving in amidation, reduction, diazotization, and deprotecting‐group reaction. The herbicidal activities of the title compounds were tested against two dicotyledonous plants and two monocotyledonous plants, in which some of them exhibited high herbicidal activities against two dicotyledonous plants in preemergence and postemergence treatments. Moreover, when the dosage was decreased to 180 and 90 g/ha, compounds F1 , F8 , and F9 showed highly selective inhibitory activities against amaranth pigweed, alfalfa, asteraceae, field sowthistle, morning glory, purslane, and velvetleaf in postemergence treatment but had no herbicidal efficacy on rape except F1 , suggesting that it be possible to find a kind of herbicides to inhibit dicotyledonous weeds in the field of dicotyledonous crops with the same genus as aforementioned weeds. 相似文献
994.
Han Huiyun Li Xingliang Han Mengmeng Liu Jingmin Yan Dan Yang Zhenjun Shang Ce Feng Yali Zhang Shumin 《Optical Review》2018,25(2):237-243
Optical Review - We have numerically investigated the required minimum cavity dispersion (RMCD) for obtaining stable pulses in net normal dispersion, graphene mode-locked, Yb-doped fiber lasers... 相似文献
995.
996.
The Soreq Applied Research Accelerator Facility (SARAF): Overview,research programs and future plans
Israel Mardor Ofer Aviv Marilena Avrigeanu Dan Berkovits Adi Dahan Timo Dickel Ilan Eliyahu Moshe Gai Inbal Gavish-Segev Shlomi Halfon Michael Hass Tsviki Hirsh Boaz Kaiser Daniel Kijel Arik Kreisel Yonatan Mishnayot Ish Mukul Ben Ohayon Michael Paul Amichay Perry Hitesh Rahangdale Jacob Rodnizki Guy Ron Revital Sasson-Zukran Asher Shor Ido Silverman Moshe Tessler Sergey Vaintraub Leo Weissman 《The European Physical Journal A - Hadrons and Nuclei》2018,54(5):91
997.
Xue Xi Ma Qianli Dong Xiangting Li Dan Yu Wensheng Wang Jinxian Liu Guixia 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2019,93(12):2444-2451
Russian Journal of Physical Chemistry A - A new nanostructure of luminescent-magnetic-electrical trifunctionality Janus nanofibers with [Fe3O4/polyvinyl pyrrolidone... 相似文献
998.
Cheng Jiang Lisha Zhao Chuanwei Xin Yu Dong Jie Shen Zhongni Xia Dan Shou Gonghua Li 《Biomedical chromatography : BMC》2022,36(2):e5255
The allergic reaction (AR) of Chinese herbal injection (CHI) has become one of the most noticeable focuses of public health in China. However, it still remains a considerable controversy as to whether low-molecular-weight components in CHI have potential sensitization. In this study, the relationship between AR and low-molecular-weight component profile of Shenmai injection was explored by an interdisciplinary technology integrating real-world evidence and ultra-performance liquid chromatography–quadrupole time-of-flight mass spectroscopy (UPLC–Q-TOF-MS). The AR information of hospitalized patients was obtained by comprehensively analyzing real-world evidence from January 2015 to June 2019 at two Chinese hospitals. The UPLC–Q-TOF-MS was exploited to systematically investigate the low-molecular-weight component profile with 50–1500 m/z mass range, and 3725 MS1 peaks were detected. The optimized partial least squares discriminant analysis model was established to map the influence of low-molecular-weight components on AR. The results of this study showed that high levels of organic acids administered intravenously might be a potential risk factor for inducing AR. By using this method, Shenmai injection with high AR risk could be recognized precisely with 100% accuracy before clinical use. 相似文献
999.
1000.