全文获取类型
收费全文 | 2146篇 |
免费 | 134篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 66篇 |
妇产科学 | 75篇 |
基础医学 | 291篇 |
口腔科学 | 26篇 |
临床医学 | 321篇 |
内科学 | 359篇 |
皮肤病学 | 11篇 |
神经病学 | 174篇 |
特种医学 | 256篇 |
外科学 | 211篇 |
综合类 | 18篇 |
一般理论 | 5篇 |
预防医学 | 222篇 |
眼科学 | 10篇 |
药学 | 117篇 |
中国医学 | 4篇 |
肿瘤学 | 105篇 |
出版年
2021年 | 25篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 43篇 |
2017年 | 31篇 |
2016年 | 46篇 |
2015年 | 48篇 |
2014年 | 46篇 |
2013年 | 66篇 |
2012年 | 85篇 |
2011年 | 87篇 |
2010年 | 53篇 |
2009年 | 68篇 |
2008年 | 85篇 |
2007年 | 121篇 |
2006年 | 78篇 |
2005年 | 121篇 |
2004年 | 93篇 |
2003年 | 69篇 |
2002年 | 80篇 |
2001年 | 70篇 |
2000年 | 73篇 |
1999年 | 60篇 |
1998年 | 39篇 |
1997年 | 40篇 |
1996年 | 37篇 |
1995年 | 19篇 |
1994年 | 26篇 |
1993年 | 23篇 |
1992年 | 32篇 |
1991年 | 35篇 |
1990年 | 36篇 |
1989年 | 34篇 |
1988年 | 35篇 |
1987年 | 41篇 |
1986年 | 33篇 |
1985年 | 43篇 |
1984年 | 19篇 |
1983年 | 31篇 |
1982年 | 26篇 |
1981年 | 25篇 |
1980年 | 19篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 25篇 |
1976年 | 16篇 |
1973年 | 10篇 |
1972年 | 10篇 |
1971年 | 13篇 |
1970年 | 12篇 |
排序方式: 共有2294条查询结果,搜索用时 15 毫秒
1.
2.
H. Maas 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1878,10(1-2):185-188
Ohne Zusammenfassung 相似文献
3.
Carmine Zoccali Renke Maas Sebastiano Cutrupi Patrizia Pizzini Piero Finocchiaro Francesco Cambareri Vincenzo Panuccio Carmela Martorano Friedrich Schulze Giuseppe Enia Giovanni Tripepi Rainer Boger 《Nephrology, dialysis, transplantation》2007,22(3):801-806
BACKGROUND AND METHODS: The endogenous inhibitor of nitric oxide synthase (NOs) asymmetrical dimethyl-arginine (ADMA) has been implicated as a possible modulator of inducible NOs during acute inflammation. We examined the evolution in the plasma concentration of ADMA measured at the clinical outset of acute inflammation and after its resolution in a series of 17 patients with acute bacterial infections. RESULTS: During the acute phase of inflammation/infection, patients displayed very high levels of C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin and nitrotyrosine. Simultaneous plasma ADMA concentration was similar to that in healthy subjects while symmetric dimethyl-arginine (SDMA) levels were substantially increased and directly related with creatinine. When infection resolved, ADMA rose from 0.62 +/- 0.23 to 0.80 +/- 0.18 micromol/l (+29%, P = 0.01) while SDMA remained unmodified. ADMA changes were independent on concomitant risk factor changes and inversely related with baseline systolic and diastolic pressure. Changes in the ADMA/SDMA ratio were compatible with the hypothesis that inflammatory cytokines activate ADMA degradation. CONCLUSIONS: Resolution of acute inflammation is characterized by an increase in the plasma concentration of ADMA. The results imply that ADMA suppression may actually serve to stimulate NO synthesis or that in this situation plasma ADMA levels may not reflect the inhibitory potential of this methylarginine at the cellular level. 相似文献
4.
Possible relevance of pigeons as an indicator species for monitoring air pollution. 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Environmental health perspectives》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P A Schilderman J A Hoogewerff F J van Schooten L M Maas E J Moonen B J van Os J H van Wijnen J C Kleinjans 《Environmental health perspectives》1997,105(3):322-330
Wild city pigeons were caught at four different locations in the Netherlands to represent areas of high (Amsterdam-high), moderate (Amsterdam-medium), and low (Maastricht and Assen) traffic density. It is assumed that local ambient air pollution decreases as a function of traffic density. In these pigeons levels of polycyclic aromatic hydrocarbon (PAH)-DNA adducts, oxidative DNA damage, and heavy metal residues were determined in kidney, lung, liver, and blood (no adduct analysis in blood). The contribution of leaded gasoline to total body lead content was estimated by measuring concentrations of Pb and its isotopes in blood. We also analyzed samples of ambient air particulate matter for PAH and heavy metal concentrations at the four different locations. Interregional differences in heavy metals in ambient air particulate matter were reflected relatively well by pigeon body loads. The higher lead and cadmium concentrations in blood, kidney, liver, and lung were found in the Amsterdam high traffic density area, followed by Amsterdam medium, Assen, and Maastricht. A high Pb concentration in blood coincided with relatively low 206Pb/207Pb values, indicating a high contribution of leaded gasoline to total blood Pb concentrations in pigeons from the Amsterdam high traffic density area. Significantly enhanced blood zinc values were found in pigeons from both locations in Amsterdam compared to pigeons from the other two areas. However, no differences in Zn tissue levels between the four different groups were found. Oxidative DNA damage, determined as the ratio of 7-Hydro-8-oxo-2'-deoxyguanosine/ deoxyguanosine, in pigeon liver was highest in Amsterdam-high, followed by Assen (low traffic density). Pb content, but not the Cd content, was positively associated with oxidative DNA damage in liver tissue. In lung tissue, a negative correlation was found between oxidative DNA damage and Zn content. These results indicate that the carcinogenic potential of Pb might be ascribed to oxygen radical formation, whereas Zn plays a protective role against oxidative DNA damage. Places with high and medium traffic density could be clearly discriminated on the basis of PAH levels in the ambient air. The PAH content in particulate air samples was not, however, reflected in total PAH-related DNA adduct levels because no differences could be observed in tissue adduct levels in pigeons from the four different locations. Our results indicate that wild city pigeons can be used as biological indicators of exposure to heavy metal pollution in outdoor air. 相似文献
5.
6.
7.
Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results 总被引:3,自引:0,他引:3
Mattrey RF; Strich G; Shelton RE; Gosink BB; Leopold GR; Lee T; Forsythe J 《Radiology》1987,163(2):339-343
In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients. 相似文献
8.
9.
10.
Cindy A. Scherb Carla Gene Rapp Marion Johnson Meridean Maas 《Rehabilitation nursing》1998,23(4):174-191
Measuring patient outcomes is important to rehabilitation nurses and the patients they serve. This article describes research conducted at the University of Iowa College of Nursing to develop the Nursing Outcomes Classification (NOC) and the validation of this research by surveys conducted through specialty nursing organizations, particularly the Association of Rehabilitation Nurses. Nurses responded to surveys designed to validate (a) the importance of outcome indicators to the achievement of an outcome and (b) nursing's contribution to the achievement of the indicators. The results of the surveys indicated that rehabilitation nurses believe that nursing makes a substantial contribution to most outcomes and indicators. 相似文献