全文获取类型
收费全文 | 2982篇 |
免费 | 50篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 57篇 |
妇产科学 | 86篇 |
基础医学 | 159篇 |
口腔科学 | 73篇 |
临床医学 | 532篇 |
内科学 | 801篇 |
皮肤病学 | 197篇 |
神经病学 | 89篇 |
特种医学 | 16篇 |
外科学 | 305篇 |
综合类 | 30篇 |
一般理论 | 54篇 |
预防医学 | 215篇 |
眼科学 | 45篇 |
药学 | 312篇 |
肿瘤学 | 49篇 |
出版年
2014年 | 24篇 |
2013年 | 62篇 |
2012年 | 28篇 |
2010年 | 80篇 |
2009年 | 80篇 |
2008年 | 28篇 |
2006年 | 22篇 |
2001年 | 37篇 |
1999年 | 72篇 |
1998年 | 98篇 |
1997年 | 154篇 |
1996年 | 143篇 |
1995年 | 103篇 |
1994年 | 101篇 |
1993年 | 96篇 |
1992年 | 76篇 |
1991年 | 80篇 |
1990年 | 81篇 |
1989年 | 61篇 |
1988年 | 90篇 |
1987年 | 65篇 |
1986年 | 77篇 |
1985年 | 51篇 |
1984年 | 73篇 |
1983年 | 66篇 |
1982年 | 62篇 |
1981年 | 66篇 |
1980年 | 46篇 |
1979年 | 56篇 |
1978年 | 50篇 |
1977年 | 52篇 |
1976年 | 27篇 |
1975年 | 31篇 |
1974年 | 28篇 |
1971年 | 35篇 |
1970年 | 20篇 |
1969年 | 26篇 |
1968年 | 27篇 |
1967年 | 20篇 |
1965年 | 20篇 |
1963年 | 22篇 |
1962年 | 27篇 |
1961年 | 22篇 |
1959年 | 28篇 |
1958年 | 47篇 |
1957年 | 42篇 |
1956年 | 50篇 |
1955年 | 43篇 |
1954年 | 43篇 |
1948年 | 26篇 |
排序方式: 共有3034条查询结果,搜索用时 15 毫秒
91.
92.
93.
Gender differences in relapse situations 总被引:1,自引:0,他引:1
94.
95.
M.-C. D. N. J. M. HUYSMANS M. C. R. B. PETERS P. G. T. VAN DER VARST A. J. M. PLASSCHAERT 《International endodontic journal》1993,26(5):294-300
Evaluation of die long-term behaviour of restorations in clinical trials can be time-consuming. A partial alternative to the clinical trial can be found in mechanical fatigue testing. The aim of this study was to evaluate the failure behaviour of post and core restored teeth when subjected to cyclic mechanical loading and to compare it with quasistatic failure. Eighty seven premolar teeth were restored with a titanium alloy post and an amalgam or composite core. Five to 21 days after restoration, the specimens were subjected to cyclic loading (frequency 5 Hz), at an angle of 45° to the long axis of the tooth. The load levels were 50,60,65 and 70% of mean quasistatic failure loads. The specimens were divided into three groups according to their survival time: short (S) (>104 cycles), intermediate (I) (104≥life>105 cycles) and long (L) (≥ 105 cycles). For both core materials failure behaviour changed after approximately 105 cycles, and the change was most marked for the composite group. Catastrophic fatigue failure consisted of core fracture in the amalgam group (three times) and of post fracture in the composite L group (four times). Three post fractures occurred at a site theoretically predisposed to fatigue failure. It was concluded that fatigue failure characteristics of post and core restorations may be very different from those of quasistatic failure. Therefore, in addition to quasistatic tests, fatigue tests are necessary, covering at least 105 load cycles. 相似文献
96.
GABRIELE MARGOS KLAUS KURTENBACH † ELSA POSNETT GUY C. BARKER HIROYUKI MATSUOKA MICHAEL G. PATON ROBERT E. SINDEN 《Parasite immunology》1995,17(4):167-176
A surface protein of Plasmodium berghei ookinetes, Pbs21, was expressed in a baculovirus-insect cell system in cell culture and in Heliothis virescens larvae. Groups of BALB/c mice received two intraperitoneal inoculations of either i) Tris-buffer or homogenized H. virescens larvae infected with wild-type baculovirus; ii) enriched, homogenized ookinetes, or Hi) homogenizedH. virescens larvae expressing recombinant Pbs21 (rPbs21). All animals immunized with ookinetes or with rPbs21 had high litres of antibodies (IgG isotype) that bound to native Pbs21. The large majority of antibodies in immune sera of both groups recognized the antigen under non-reducing but not under reducing conditions. The predominant IgG-sub-classes in mice immunized with ookinetes was IgGl and in mice immunized with rPbs21, the subclasses were IgGl and IgG2a. Immunization with rPbs21 reduced the infec-tivity of P. berghei to mosquitoes by 91% compared to a 99% reduction following immunization with ookinetes. This preliminary data indicate that rPbs21 expressed in this eukaryotic system induces a transmission-blocking immunity which is more effective than that achieved using rPbsll expressed in Escherichia coli (Matsuoka et al. 1994). 相似文献
97.
98.
ZHENPING TIAN CHING GU ROGER W. ROESKE MINGMING ZHOU ROBERT L. VAN ETTEN 《Chemical biology & drug design》1993,42(2):155-158
A practical and convenient procedure for making phosphotyrosine-containing peptides by the solid-phase method was developed. Phosphotyrosine was incorporated via Boc-Tyr(PO3Bzl2)-OH. The completed peptide was cleaved from the solid support by treatment with 1 M TMSBr-thioanisole-TFA. By gel-phase 31P-NMR spectroscopy we found that one of the benzyl protecting groups on phosphate was completely removed by two consecutive runs of Boc deprotection with 50% TFA-DCM. However, the other benzyl group remained intact throughout the synthesis (35 cycles). 相似文献
99.
ROBERT W. SHAW HAMISH M. ERASER 《BJOG : an international journal of obstetrics and gynaecology》1984,91(9):913-916
Summary. A luteinizing hormone releasing hormone agonist, d-Ser(But)6 des Gly10 -LHRH ethylamide, was administered intranasally to four women with unexplained ovulatory menorrhagia. Dramatic reductions in excessive menstrual blood losses were induced without significant side-effects, although the pattern of loss returned to pretreatment levels within 2 months of ceasing therapy. 相似文献
100.