全文获取类型
收费全文 | 2038864篇 |
免费 | 150245篇 |
国内免费 | 6059篇 |
专业分类
耳鼻咽喉 | 27245篇 |
儿科学 | 66344篇 |
妇产科学 | 57378篇 |
基础医学 | 296075篇 |
口腔科学 | 56345篇 |
临床医学 | 188663篇 |
内科学 | 397593篇 |
皮肤病学 | 41545篇 |
神经病学 | 167526篇 |
特种医学 | 76937篇 |
外国民族医学 | 669篇 |
外科学 | 297592篇 |
综合类 | 44575篇 |
现状与发展 | 1篇 |
一般理论 | 686篇 |
预防医学 | 165485篇 |
眼科学 | 45785篇 |
药学 | 148628篇 |
6篇 | |
中国医学 | 4519篇 |
肿瘤学 | 111571篇 |
出版年
2019年 | 16356篇 |
2018年 | 22945篇 |
2017年 | 17601篇 |
2016年 | 19104篇 |
2015年 | 21710篇 |
2014年 | 30229篇 |
2013年 | 46845篇 |
2012年 | 63791篇 |
2011年 | 67931篇 |
2010年 | 40035篇 |
2009年 | 37265篇 |
2008年 | 62937篇 |
2007年 | 66623篇 |
2006年 | 66849篇 |
2005年 | 64983篇 |
2004年 | 61966篇 |
2003年 | 59371篇 |
2002年 | 58060篇 |
2001年 | 91027篇 |
2000年 | 93728篇 |
1999年 | 79118篇 |
1998年 | 22444篇 |
1997年 | 20435篇 |
1996年 | 20154篇 |
1995年 | 19033篇 |
1994年 | 17937篇 |
1993年 | 16933篇 |
1992年 | 62912篇 |
1991年 | 61266篇 |
1990年 | 59573篇 |
1989年 | 56885篇 |
1988年 | 52780篇 |
1987年 | 51670篇 |
1986年 | 49313篇 |
1985年 | 47217篇 |
1984年 | 35624篇 |
1983年 | 30299篇 |
1982年 | 18317篇 |
1979年 | 32545篇 |
1978年 | 23062篇 |
1977年 | 19164篇 |
1976年 | 18606篇 |
1975年 | 19515篇 |
1974年 | 23666篇 |
1973年 | 22954篇 |
1972年 | 21450篇 |
1971年 | 19910篇 |
1970年 | 18704篇 |
1969年 | 17271篇 |
1968年 | 16484篇 |
排序方式: 共有10000条查询结果,搜索用时 31 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.
In a previous study, we described a new method [3] to measure Na reabsorption by each segment of the human nephron independently. Reabsorption was expressed as equivalent volumes of solute-free water (CH2O) generated by the loop of Henle (CH2O-HL) and by the distal tubule (CH2O-DT), and dissipated by back diffusion (BD) across collecting ducts (CH2O-BD). These data were obtained during maximal water diuresis (MWD). The present study was undertaken to calculate CH2O-HL by experiments performed during maximal antidiuresis (MA). For this purpose, a new theoretical approach was devised, described by algebraic equations which allowed calculations of segmental transport during MA alone, where only CH2O-HL could be calculated independently. The study was performed on 14 normal volunteers who were studied twice by clearance measurements, firstly during MWD and again during MA. In each experiment, clearance periods were performed during baseline conditions and during the administration of furosemide (0.7 mg/kg bolus injection followed by 0.06 mg/kg/min maintenance infusion). From the values measured during either condition, segmental reabsorption was calculated. During MWD, CH2O-HL averaged 19.4 + 10.4, during MA 20.4 + 8.0 ml/min/GFR X 100; p greater than 0.05. The paired measurements were significantly correlated (r = 0.80; p less than 0.01). These data demonstrate that CH2O-HL obtained with the original theory is a reproducible result that can be confirmed with independent measurements obtained during different experimental conditions. Thus, measurements of segmental Na transport in the human nephron are feasible and can contribute important informations on disease states. 相似文献
999.
F Brown 《British medical journal》1987,295(6594):347-348
1000.
S Bengtson A Carlsson M Relander K Knutson L Lidgren 《Acta orthopaedica Scandinavica》1987,58(6):662-665
Ten knees with early tissue breakdown after knee arthroplasty resulting in exposed prostheses were treated with different plastic surgical techniques. Six knees were successfully covered: four using a gastrocnemius musculocutaneous flap, one using a fasciocutaneous flap, and one using split-skin grafts. Four knees failed: two using local skin flaps and two using split-skin grafts. A gastrocnemius musculocutaneous flap seems to provide a reliable coverage of the exposed knee joint. 相似文献