全文获取类型
收费全文 | 2479篇 |
免费 | 125篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 55篇 |
妇产科学 | 31篇 |
基础医学 | 308篇 |
口腔科学 | 40篇 |
临床医学 | 159篇 |
内科学 | 724篇 |
皮肤病学 | 73篇 |
神经病学 | 258篇 |
特种医学 | 37篇 |
外科学 | 366篇 |
综合类 | 8篇 |
预防医学 | 73篇 |
眼科学 | 38篇 |
药学 | 196篇 |
中国医学 | 2篇 |
肿瘤学 | 223篇 |
出版年
2023年 | 15篇 |
2022年 | 30篇 |
2021年 | 73篇 |
2020年 | 27篇 |
2019年 | 37篇 |
2018年 | 59篇 |
2017年 | 44篇 |
2016年 | 57篇 |
2015年 | 50篇 |
2014年 | 65篇 |
2013年 | 70篇 |
2012年 | 129篇 |
2011年 | 144篇 |
2010年 | 72篇 |
2009年 | 56篇 |
2008年 | 123篇 |
2007年 | 124篇 |
2006年 | 116篇 |
2005年 | 114篇 |
2004年 | 101篇 |
2003年 | 108篇 |
2002年 | 103篇 |
2001年 | 64篇 |
2000年 | 80篇 |
1999年 | 67篇 |
1998年 | 23篇 |
1997年 | 21篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1992年 | 68篇 |
1991年 | 43篇 |
1990年 | 43篇 |
1989年 | 36篇 |
1988年 | 25篇 |
1987年 | 49篇 |
1986年 | 37篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 19篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 34篇 |
1978年 | 17篇 |
1977年 | 12篇 |
1972年 | 13篇 |
1971年 | 11篇 |
1970年 | 14篇 |
1969年 | 16篇 |
1968年 | 18篇 |
1967年 | 11篇 |
排序方式: 共有2617条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
K Tamazawa H Arima T Kojima Y Isomura M Okada S Fujita T Furuya T Takenaka O Inagaki M Terai 《Journal of medicinal chemistry》1986,29(12):2504-2511
Four enantiomers (3a-d) of the title compound, YM-09730 (3), were synthesized by the reaction of (-)- or (+)-5-(methoxycarbonyl)-2, 6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine-3-carboxylic acid (1a or 1b) with (S)- or (R)-1-benzyl-3-pyrrolidinol (2a or 2b). [3H]Nitrendipine binding affinity and coronary vasodilating activity of these compounds were evaluated. The absolute configuration of the most potent enantiomer (3a) with the longest duration was unequivocally determined to be (S)-1,4-dihydropyridine-C4 and (S)-pyrrolidine-C3 (S,S) by X-ray crystallographic study on 3a X HBr as well as 3a X HCl. The configuration of 1a corresponds to R, and the other enantiomers of 3 were respectively determined by chemical correlation. The potency order of the four enantiomers was (S,S)-3a greater than (S,R)-3b greater than (R,R)-3d greater than (R,S)-3c. Latent chiral characters of nifedipine derivatives with the identical ester groups were assigned by comparison of their puckering modes of 1,4-dihydropyridine (DHP) rings with those found in 3a X HCl or 3a X HBr. On the basis of the assignment, it has been revealed that the (S)-DHP nifedipine derivatives possess the synperiplanar carbonyl group at C5. The conformational restriction may be a factor causing stereoselectivity of antagonism. 相似文献
5.
Hiroshi Morita MD Douglas P. Zipes MD Shiho T. Morita MD Jiashin Wu PhD 《Heart rhythm》2007,4(1):66-74
BACKGROUND: The Brugada syndrome is characterized by ST-segment elevation on the ECG, especially in the right precordial leads sensitive to the right ventricular outflow tract (RVOT). OBJECTIVES: The purpose of this study was to evaluate the hypothesis that right ventricular electrophysiologic heterogeneity caused arrhythmogenicity in the Brugada syndrome. METHODS: Action potentials (APs) were mapped on the epicardium of 14 RVOT preparations and on the transmural surfaces of 15 pairs of RVOT and right ventricular anteroinferior (RVAI) preparations isolated from canine hearts. Brugada ECG and arrhythmias were induced with pilsicainide (2.5-12.5 micromol/L), pinacidil (1.25-12.5 micromol/L), and terfenadine (2.0 micromol/L). RESULTS: Low doses of drugs elevated the J-ST segment and induced APs with both short and long action potential durations (APDs) in contiguous RVOT epicardial regions. In addition, APs in the RVOT had a larger phase 1 notch and longer APD than in RVAI. The longest APDs were in the epicardium in RVOT but in the endocardium in RVAI regions. High doses of drugs eliminated the phase 2 dome of the AP and abbreviated APDs in the epicardium but not in endocardium and reduced the epicardial heterogeneity of APs but increased the transmural gradient of APD in 14 (93%) of the RVOT preparations. In contrast, abbreviations of epicardial APDs occurred in only 4 (27%) of the RVAI preparations. Ventricular tachycardia occurred more frequently in the RVOT (47%) than in paired RVAI preparations (7%). Blocking the transient outward current reduced the heterogeneity of APs and eliminated arrhythmogenicity in all preparations. CONCLUSION: Compared with the RVAI region, the RVOT has greater electrophysiologic heterogeneity that contributes to arrhythmogenicity in this model of Brugada syndrome. 相似文献
6.
7.
K. Arima Minako Nakamura Nobuhiko Sunohara Masafumi Ogawa Midori Anno Yoko Izumiyama Shigeo Hirai Kazuhiko Ikeda 《Acta neuropathologica》1997,93(6):558-566
Coiled bodies and interfascicular threads are conspicuous white matter abnormalities of brains of patients with progressive
supranuclear palsy (PSP). Both structures are argyrophilic and immunoreactive for the microtubule-binding protein tau. This
report concerns the ultrastructural localization of interfascicular threads and their relationship to coiled bodies in five
PSP patients. We showed for the first time that abnormal tubules with a 13- to 15-nm diameter and fuzzy outer contours were
the common structures of coiled bodies in the oligodendroglial perikarya and of interfascicular threads. Moreover, the tubules
were immunolabeled by anti-tau antibodies. The abnormal tau-positive tubules of interfascicular threads were located in the
inner loop of the myelin sheath. Our study further indicated that the thread-like structures in the white matter comprised,
at least in part, oligodendroglial processes, and that they were also present in gray matter. We consider that the formation
of coiled bodies in the perikarya and of interfascicular threads represents a common cytoskeletal abnormality of the oligodendroglia
of PSP patients. Moreover, even though the white matter alterations of PSP resemble those of corticobasal degeneration, there
are certain ultrastructural differences in the abnormal oligodendroglial tubules of the two diseases.
Received: 4 October 1996 / Accepted: 6 December 1996 相似文献
8.
9.
Kunihiro Ichinose Mitsuru Nakamura Kenji Takezawa Ichiro Masutomi Yoichi Shima Yoko Hirayama Kahoko Sorimachi Teruhiko Shimizu Hiroyo Ishikawa Namiko Kaji Sayaka Nakajima Michiko Wataru Shiho Nishigaki Hiroshi Suwa Yosuke Toyama Masaki Okumura Yoshikazu Ishitsuka Ken Shimizu Kazuya Kokubo Kenji Sasaki Shodai Saito 《Seishin shinkeigaku zasshi》2006,108(9):945-954
10.
Photoaging and oxidative stress 总被引:5,自引:0,他引:5
Chikako Nishigori† Yukari Hattori Yaeno Arima Yoshiki Miyachi 《Experimental dermatology》2003,12(S2):18-21