全文获取类型
收费全文 | 3453147篇 |
免费 | 287775篇 |
国内免费 | 13631篇 |
专业分类
耳鼻咽喉 | 48367篇 |
儿科学 | 111896篇 |
妇产科学 | 89303篇 |
基础医学 | 546922篇 |
口腔科学 | 90890篇 |
临床医学 | 307566篇 |
内科学 | 617124篇 |
皮肤病学 | 91146篇 |
神经病学 | 293932篇 |
特种医学 | 137314篇 |
外国民族医学 | 686篇 |
外科学 | 536457篇 |
综合类 | 102690篇 |
现状与发展 | 23篇 |
一般理论 | 2270篇 |
预防医学 | 289166篇 |
眼科学 | 78844篇 |
药学 | 237809篇 |
23篇 | |
中国医学 | 9658篇 |
肿瘤学 | 162467篇 |
出版年
2021年 | 55007篇 |
2020年 | 35043篇 |
2019年 | 58091篇 |
2018年 | 71203篇 |
2017年 | 54226篇 |
2016年 | 59822篇 |
2015年 | 73980篇 |
2014年 | 108147篇 |
2013年 | 173309篇 |
2012年 | 91895篇 |
2011年 | 91807篇 |
2010年 | 116604篇 |
2009年 | 121171篇 |
2008年 | 79755篇 |
2007年 | 83147篇 |
2006年 | 93806篇 |
2005年 | 89359篇 |
2004年 | 91488篇 |
2003年 | 82646篇 |
2002年 | 72846篇 |
2001年 | 110055篇 |
2000年 | 104119篇 |
1999年 | 102912篇 |
1998年 | 66077篇 |
1997年 | 63497篇 |
1996年 | 61443篇 |
1995年 | 56888篇 |
1994年 | 51146篇 |
1993年 | 47677篇 |
1992年 | 72826篇 |
1991年 | 69884篇 |
1990年 | 66385篇 |
1989年 | 64850篇 |
1988年 | 60014篇 |
1987年 | 58807篇 |
1986年 | 55207篇 |
1985年 | 55212篇 |
1984年 | 49835篇 |
1983年 | 45401篇 |
1982年 | 41903篇 |
1981年 | 39670篇 |
1980年 | 37190篇 |
1979年 | 40814篇 |
1978年 | 35729篇 |
1977年 | 32697篇 |
1976年 | 30039篇 |
1975年 | 28948篇 |
1974年 | 29663篇 |
1973年 | 28570篇 |
1972年 | 26525篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Spectral analysis of the electroencephalogram in neonatal rats chronically treated with the NMDA antagonist MK-801. 总被引:1,自引:0,他引:1
J A Gorter M Veerman M Mirmiran N P Bos M A Corner 《Brain research. Developmental brain research》1991,64(1-2):37-41
In order to study the involvement of NMDA-receptor activation in brain development, rat pups were chronically treated with the non-competitive NMDA antagonist MK-801 during the neonatal period. We recorded the cortical EEG at various vigilance states throughout the treatment period. Spectral analysis of the EEG showed reduced power in the delta (delta) frequency range (1.5-4 Hz) during quiet sleep and less power in the theta (theta) range (4-7 Hz) during REM-sleep in MK-801 animals than in controls. No significant differences were found for the total time spent in each of the different vigilance states. We conclude that chronic MK-801 treatment probably causes a developmental retardation in state-related brain activities. 相似文献
992.
A total of 102 patients were examined, 32 of these with true eczema, 38 with exudative mycosis of the soles, and 32 with eczema etiologically related to a fungal infection. Analysis of the immune and biochemical reactions in the examinees has shown a marked reduction of adenyl nucleotides in the leukocytic suspension and neutrophils of patients with a mycotic infection as against those with true eczema. The lowest creatine phosphate levels were detected in the leukocytic suspension and neutrophils of the patients suffering from eczema etiologically related to mycosis and exudative mycosis of the soles. These results give grounds to search for effective corrective therapy. 相似文献
993.
994.
P G Crosignani A M Mattei C Scarduelli V Cavioni P Boracchi 《Human reproduction (Oxford, England)》1989,4(8):910-912
This paper reports the changes in prolactin levels after 12 spontaneous and 52 induced pregnancies in 54 women with unambiguous hyperprolactinaemia (median plasma prolactin levels 67.5 ng/ml, range 40-400). Twenty-three of the patients showed radiological evidence of prolactinoma. The pregnancies were induced in 37 patients by bromocriptine, in nine by metergoline, in two by lisuride and in four by other treatments. Of the 64 pregnancies, 16 ended in spontaneous abortion, while 48 went to term. Follow-up was continued for at least 6 months after delivery or until the end of lactation. In a control group of 32 hyperprolactinaemic women (median prolactin 70 ng/ml, range 40-400) not wishing to become pregnant, prolactin changes were similarly registered over a mean period of 15 months without any treatment (range 6-38 months). After pregnancy, a significant downward trend of plasma prolactin was observed in the puerperal women with a 'normalization' rate of 17%. No changes were observed in the 32 controls who did not become pregnant. 相似文献
995.
J M Debets R Kampmeijer M P van der Linden W A Buurman C J van der Linden 《Critical care medicine》1989,17(6):489-494
Tumor necrosis factor (TNF) cachectin has been implicated as an important host mediator responsible for shock and multiple organ failure (MOF) observed during sepsis. Using a sensitive enzyme-linked immunosorbent assay, we measured plasma TNF levels in 43 septic patients suffering from a broad range of diseases. Measurements were taken on the day that sepsis was diagnosed. Eleven patients had detectable TNF plasma levels ranging from 10 to 100 pg/ml (TNF-positive group); in 32 patients circulating TNF could not be detected (TNF-negative group). The groups did not differ significantly as to age, underlying disease, percentage positive bacteremia and bacteriologic profile, sepsis score, and extent of MOF. Eight (73%) of 11 TNF-positive patients died from sepsis during ICU stay, vs. 11 (34%) of 32 TNF-negative patients (p less than .05). This study demonstrates that sepsis is accompanied by detectable circulating TNF in 25% of the cases, and for these patients mortality is twice that for comparable TNF-negative patients. 相似文献
996.
997.
P Brunel A Seigneuric G Leguay 《Archives des maladies du coeur et des vaisseaux》1989,82(11):1819-1823
The authors analysed the prevalence of atrioventricular conduction defects and sinus node dysfunction by Holter monitoring in three population groups with similar clinical characteristics: 50 controls (Group I), 17 physically fit subjects with an atrioventricular conduction defect on the resting ECG which was usually asymptomatic (Group II), and 48 professional pilots who were also physically fit but who had no conduction defects on resting ECG (Group III). The 24 hour recordings showed: --a similar incidence of sinus dysrhythmias and atrioventricular conduction defects in the three groups although the frequency of low degree block was a little higher in sportsmen; --a preponderance of the association of first degree block and nocturnal Luciani-Wenckebach periods, sometimes with episodes of Mobitz II block; --the absence of progression to high-degree atrioventricular block. Holter monitoring would therefore seem to be a good method of detecting and following up abnormalities of sinus node function and atrioventricular conduction defects in asymptomatic patients. In addition, it gives a qualitative and quantitative assessment of the recorded changes and provides a means of monitoring their evolution. 相似文献
998.
The aqueous, organic, and volatile oil extracts of leaves of Eugenia uniflora Linn. Family Myrtaceae were investigated for antibacterial properties using agar dilution techniques. The aqueous extract was the most active against the organisms compared to the organic and volatile oil extracts. The extracts were found to inhibit Gram positive Staphylococcus aureus and Bacillus subtilis and Gram negative Escherichia coli and Shigella dysentcriae. Pseudomonas aeruginosa, Klebsiella pneumoniac, and Salmonella typhi were not inhibited. 相似文献
999.
Thiarubrine A, a dithiacyclohexadiene polyine from the roots of Chaenactis douglasii, and a related dithiacyclohexadiene from Rudbeckia hirta exhibit strong light-independent antibacterial and antifungal activity. This activity is enhanced by exposure to visible light. Visible light also converts the compounds to the corresponding thiophenes. These are antibiotic only when irradiated with UV-A. Dithiacyclohexadienes are the first polyines to exhibit such complex mechanisms of toxicity towards microorganisms. 相似文献
1000.
Summary Split or full thickness eyelid defects resulting from tumor destruction or surgical excision present a dilemma for plastic and reconstructive surgeons. Full thickness eyelid replacement requires composite grafting of the skin, together with tarsal support of its substitute and mucosa. The flap described by Fricke in 1829 was used for reconstruction of anterior lamella in six lower eyelid defects. In three of our cases chondromucosal grafts taken from nasal septum were utilized for posterior lamella repair. The results have been satisfactory from a functional and cosmetic standpoint. 相似文献