全文获取类型
收费全文 | 513篇 |
免费 | 36篇 |
国内免费 | 8篇 |
专业分类
儿科学 | 51篇 |
妇产科学 | 3篇 |
基础医学 | 52篇 |
口腔科学 | 11篇 |
临床医学 | 71篇 |
内科学 | 97篇 |
皮肤病学 | 2篇 |
神经病学 | 8篇 |
特种医学 | 136篇 |
外科学 | 21篇 |
综合类 | 8篇 |
预防医学 | 20篇 |
眼科学 | 5篇 |
药学 | 35篇 |
中国医学 | 2篇 |
肿瘤学 | 35篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 38篇 |
1997年 | 60篇 |
1996年 | 42篇 |
1995年 | 32篇 |
1994年 | 34篇 |
1993年 | 25篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 17篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 5篇 |
排序方式: 共有557条查询结果,搜索用时 15 毫秒
1.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
2.
K K Valu T A Gourdie T J Boritzki G L Gravatt B C Baguley W R Wilson L P Wakelin P D Woodgate W A Denny 《Journal of medicinal chemistry》1990,33(11):3014-3019
Four series of acridine-linked aniline mustards have been prepared and evaluated for in vitro cytotoxicity, in vivo antitumor activity, and DNA cross-linking ability. The anilines were attached to the DNA-intercalating acridine chromophores by link groups (-O-, -CH2-, -S-, and -SO2-) of widely varying electronic properties, providing four series of widely differing mustard reactivity where the alkyl chain linking the acridine and mustard moieties was varied from two to five carbons. Relationships were sought between chain length and biological properties. Within each series, increasing the chain length did not alter the reactivity of the alkylating moiety but did appear to position it differently on the DNA, since cross-linking ability (measured by agarose gel assay) altered with chain length, being maximal with the C4 analogue. The in vivo antitumor activities of the compounds depended to some extent on the reactivity of the mustard, with the least reactive SO2 compounds being inactive. However, DNA-targeting did appear to allow the use of less reactive mustards, since the S-linked acridine mustards showed significant activity whereas the parent S-mustard did not. Within each active series, the most active compound was the C4 homologue, suggesting some relationship between activity and extent of DNA alkylation. 相似文献
3.
Paediatric dacryocystorhinostomy 总被引:1,自引:0,他引:1
KN Hakin FRCS FRCOphth TJ Sullivan FRACO FRACS A Sharma FCOphth † RAN Welham FRCS FCOphth † 《Clinical & experimental ophthalmology》1994,22(4):231-235
Of 258 cases of dacryocystorhinostomy performed on children in the period September 1981 to September 1991, 130 were for simple, unresolved congenital nasolacrimal duct obstruction. Other indications for surgery included punctal agenesis, lacrimal fistula, post-traumatic and post-inflammatory canalicular obstruction. Of 177 children without canalicular pathology, 171 (96%) were relieved of symptoms with one operation, without canalicular intubation. Of 81 cases with canalicular disease, 55 of 70 (79%) who underwent DCR plus canalicular intubation, and 10 of 11 who underwent DCR plus Lester-Jones tube, were substantially improved with one operation. No child required peroperative or postoperative blood transfusion. Dacryocystorhinostomy in childhood, in experienced surgical hands, is a safe procedure, achieving relief of symptoms in most cases, particularly in the absence of canalicular disease. 相似文献
4.
5.
6.
Factors influencing women to undergo screening mammography 总被引:2,自引:0,他引:2
7.
8.
9.
10.