全文获取类型
收费全文 | 2096853篇 |
免费 | 154182篇 |
国内免费 | 5283篇 |
专业分类
耳鼻咽喉 | 28104篇 |
儿科学 | 63050篇 |
妇产科学 | 55453篇 |
基础医学 | 304200篇 |
口腔科学 | 60436篇 |
临床医学 | 195394篇 |
内科学 | 405753篇 |
皮肤病学 | 42310篇 |
神经病学 | 170001篇 |
特种医学 | 78701篇 |
外国民族医学 | 432篇 |
外科学 | 311969篇 |
综合类 | 43791篇 |
现状与发展 | 2篇 |
一般理论 | 668篇 |
预防医学 | 164013篇 |
眼科学 | 46853篇 |
药学 | 158490篇 |
9篇 | |
中国医学 | 4933篇 |
肿瘤学 | 121756篇 |
出版年
2019年 | 16119篇 |
2018年 | 23021篇 |
2017年 | 17548篇 |
2016年 | 19213篇 |
2015年 | 21936篇 |
2014年 | 30035篇 |
2013年 | 45869篇 |
2012年 | 62881篇 |
2011年 | 66373篇 |
2010年 | 38870篇 |
2009年 | 36246篇 |
2008年 | 62317篇 |
2007年 | 65572篇 |
2006年 | 66425篇 |
2005年 | 63983篇 |
2004年 | 61359篇 |
2003年 | 58588篇 |
2002年 | 56992篇 |
2001年 | 104474篇 |
2000年 | 107888篇 |
1999年 | 90250篇 |
1998年 | 23435篇 |
1997年 | 21047篇 |
1996年 | 20884篇 |
1995年 | 19671篇 |
1994年 | 18331篇 |
1993年 | 17073篇 |
1992年 | 70502篇 |
1991年 | 68445篇 |
1990年 | 66288篇 |
1989年 | 63737篇 |
1988年 | 58698篇 |
1987年 | 57160篇 |
1986年 | 54002篇 |
1985年 | 51656篇 |
1984年 | 37995篇 |
1983年 | 32264篇 |
1982年 | 18202篇 |
1979年 | 34230篇 |
1978年 | 23685篇 |
1977年 | 19785篇 |
1976年 | 18497篇 |
1975年 | 19520篇 |
1974年 | 23821篇 |
1973年 | 22891篇 |
1972年 | 21436篇 |
1971年 | 20185篇 |
1970年 | 18931篇 |
1969年 | 17493篇 |
1968年 | 16360篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors. 相似文献
992.
The effect of some tricyclic antidepressants on the inhibition of mouse brain monoamine oxidase in-vivo by phenelzine 总被引:1,自引:0,他引:1
Four tricyclic antidepressants, amitriptyline, imipramine, desipramine and iprindole have been shown to partially protect mouse brain monoamine oxidase in-vivo from the irreversible enzyme inhibition produced by subsequent injection of phenelzine. Levels of protection were similar when the enzyme was assayed with selective substrates (5-hydroxytryptamine and phenethylamine) for both the A and B forms of the enzyme. Although other explanations cannot at this stage be ruled out, these observations are consistent with the tricyclic antidepressants acting as reversible inhibitors of brain monoamine oxidase in-vivo. 相似文献
993.
994.
995.
Addison's disease is rarely caused by metastatic cancer. We report a unique case of hypoadrenalism owing to metastatic transitional cell carcinoma of the bladder. The relevant literature is reviewed. 相似文献
996.
997.
We undertook a prospective study using arthroscopy to determine the intraarticular derangement caused by initial anterior shoulder dislocations. Of our 32 patients, 15 (47%) had a grade I, grade II, or grade III Hill-Sachs lesion. The patients were 29 men and 3 women whose ages ranged from 15 to 28 years (mean 22 years). All of the patients studied were United States military personnel or members of their families. None of the patients had had prior injuries of the affected shoulder, and all underwent arthroscopy within 72 h of injury. Few reports describe a Hill-Sachs lesion in a patient following a single anterior dislocation. Early reports of this lesion were based on indirect (radiographic) evidence. Our arthroscopic findings indicate that the incidence of this lesion after one anterior dislocation is higher than previously thought. 相似文献
998.
Uptake of iodine-123 MIBG by pheochromocytomas, paragangliomas, and neuroblastomas: a histopathological comparison 总被引:2,自引:0,他引:2
J Bomanji D A Levison W D Flatman T Horne P M Bouloux G Ross K E Britton G M Besser 《Journal of nuclear medicine》1987,28(6):973-978
The percentage uptake of [123I]metaiodobenzylguanidine (MIBG) by tumors of the paraganglion system is compared with the number of neurosecretory granules (assessed by both light and electron microscopy) in the subsequently resected tumors in six patients. Iodine-123 MIBG was injected intravenously; the tumor uptake of [123I]MIBG varied between 0.001% and 0.14% of the injected dose per gram of tumor tissue at 22 hr. The number of neurosecretory granules in tissue sections was scored on a scale of I-III. A direct proportional correlation was found between the percentage uptake of [123I]MIBG by the tumor and the number of neurosecretory granules in the tissue sections but not with plasma or urinary catecholamines. This technique for imaging reflects the storage status of the tumor better than plasma and urinary catecholamine measurements. 相似文献
999.
Up to now two abnormal nephrographic patterns have been described as a result of arterial hypotension as an adverse response to urographic contrast material. We would like to describe a third pattern. 相似文献
1000.
(E)-5-(2-Bromovinyl)-2'-deoxyuridine (1; BrVUdR) inhibits the replication of herpes simplex virus type 1 (HSV-1) and of varicella-zoster virus (VZV) in vitro at concentrations of 0.01 to 0.23 mumol/l, whereas herpes simplex virus type 2 (HSV-2) is influenced only at 5.5 to 27 mumol/l. In comparison to some classical and newly developed antiherpetics, i. e. 5-iodo-2'-desoxyuridine (2; idoxuridine, IDU), 9-beta-D-arabinofuranosyladenine (4; vidarabine Ara-A), 9-(2-hydroxyethoxymethyl) guanine (5; acyclovir, ACV) and 2'-fluoro-5-iodo-1-beta-D-aracytosine (6;FIAC) the following order of decreasing activity was found:1 greater than 6 greater than 5 greater than 2 greater than 4 (against HSV-1) and 6 greater than 2 greater than 5 greater than 1 greater than 4 (against HSV-2). The high selectivity of the antiviral effect of BrVUdR towards HSV-1 and TZV is based on the fact, that proliferation of different mammalian cell lines is inhibited by 50% only at concentrations as high as 90 to 170 mumol/l, resulting in a therapeutical index of 1000 to 10,000. Successful treatment of an HSV-1 encephalitis in mice as well as an HSV-1 keratitis of rabbits confirmed the efficiency of 1 in experimental animal infections. No toxic side effects in both local and systemic applications were observed. Promising data from cell culture and animal experiments recommend 1 as a potential candidate for the local and systemic treatment of HSV-1 and VZV infections in man. 相似文献