全文获取类型
收费全文 | 2440872篇 |
免费 | 189237篇 |
国内免费 | 8405篇 |
专业分类
耳鼻咽喉 | 34008篇 |
儿科学 | 76308篇 |
妇产科学 | 68960篇 |
基础医学 | 338075篇 |
口腔科学 | 70570篇 |
临床医学 | 215094篇 |
内科学 | 487913篇 |
皮肤病学 | 57183篇 |
神经病学 | 198440篇 |
特种医学 | 98900篇 |
外国民族医学 | 629篇 |
外科学 | 381478篇 |
综合类 | 57646篇 |
现状与发展 | 8篇 |
一般理论 | 818篇 |
预防医学 | 183700篇 |
眼科学 | 55127篇 |
药学 | 178061篇 |
8篇 | |
中国医学 | 4765篇 |
肿瘤学 | 130823篇 |
出版年
2018年 | 23121篇 |
2016年 | 21365篇 |
2015年 | 23953篇 |
2014年 | 33503篇 |
2013年 | 50632篇 |
2012年 | 63923篇 |
2011年 | 68274篇 |
2010年 | 41783篇 |
2009年 | 40663篇 |
2008年 | 64699篇 |
2007年 | 69853篇 |
2006年 | 71222篇 |
2005年 | 68875篇 |
2004年 | 66384篇 |
2003年 | 64596篇 |
2002年 | 62320篇 |
2001年 | 115596篇 |
2000年 | 119203篇 |
1999年 | 100301篇 |
1998年 | 28764篇 |
1997年 | 25945篇 |
1996年 | 26276篇 |
1995年 | 25803篇 |
1994年 | 24036篇 |
1993年 | 22513篇 |
1992年 | 80867篇 |
1991年 | 78480篇 |
1990年 | 76184篇 |
1989年 | 73568篇 |
1988年 | 68379篇 |
1987年 | 67346篇 |
1986年 | 63922篇 |
1985年 | 61171篇 |
1984年 | 46458篇 |
1983年 | 39171篇 |
1982年 | 24058篇 |
1981年 | 21831篇 |
1980年 | 20473篇 |
1979年 | 43091篇 |
1978年 | 31068篇 |
1977年 | 26622篇 |
1976年 | 24253篇 |
1975年 | 26408篇 |
1974年 | 31280篇 |
1973年 | 30158篇 |
1972年 | 28436篇 |
1971年 | 26514篇 |
1970年 | 24707篇 |
1969年 | 23485篇 |
1968年 | 21993篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
971.
H. Nilsson J. Johansson K. Svanberg S. Svanberg G. Jori E. Reddi A. Segalla D. Gust A. L. Moore T. A. Moore 《British journal of cancer》1997,76(3):355-364
The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated. 相似文献
972.
Changes on serial assessments of brain MRI lesion load are used for monitoring therapeutic efficacy in patients with multiple
sclerosis (MS). We assessed the accuracy and reliability of conventional spin-echo (CSE) and fast spin-echo (FSE) sequences
for measurement of lesion volume using a semiautomated contour technique. Cranial CSE and FSE examinations of 18 patients
with secondary progressive MS were studied. The mean lesion load was slightly higher with the CSE sequence (p = 0.002). Intraobserver
variability was significantly higher for FSE than for CSE, according to both the coefficient of variation between two measurements
(mean 2.48 % and 1.35 % respectively, p < 0.05) and back-transformed 95 % limits of agreement (1.005–1.060 for FSE; 0.988–1.019
for CSE). Although FSE sequences are quicker and the total lesion volume measurements are similar to those obtained with CSE,
the poorer reproducibility raises doubts about the use of FSE to replace CSE in clinical trials.
Received: 26 March 1996 Accepted: 4 April 1996 相似文献
973.
A. Heinig S. H. Heywang-Köbrunner P. Viehweg D. Lampe J. Buchmann R. P. Spielmann 《Der Radiologe》1997,37(9):710-717
Summary
Early recognition of recurrence and work-up of clinically indeterminate lesions may be impaired after reconstruction with
silicone implants due to superimposition of the implant or to scarring. This study was undertaken to evaluate the use of contrast-enhanced
MRI in patients with silicone implant after breast cancer. Contrast-enhanded MRI was offered to 169 patients. Comparative
two- to three-view mammography was also performed in 169 patients, as well as comparative sonography in 144 patients. Conventional
imaging and clinical examination detected only 8/13 recurrences, whereas 12/13 were detected by MRI. One recurrence had been
visible as a strongly enhancing 2-mm dot in a previous examination (2 years before), but was not called. It was therefore
counted as false negative. In addition, multicentricity was detected by MRI alone in two of three cases. MRI correctly diagnosed
scar tissue in all cases with indeterminate findings. However, due to false-positive calls caused by enhancing granulomas
specificity could not be improved. Contrast-enhanded MRI allowed decisive additional information in our study group and improved
the sensitivity significantly (concerning all diagnoses). Contrast-enhanded MRI is recommended in patients with diagnostic
problems or high risk of recurrence after silicone implants.
相似文献
974.
975.
976.
David A. Rothenberger M.D. 《Diseases of the colon and rectum》1997,40(5):632-635
977.
降糖饮降糖作用的实验研究 总被引:2,自引:0,他引:2
降糖饮以8.1,15.0,30。0g.kg^-1灌胃予鼠,连续10天。结果表明降饮对正常小鼠大鼠血糖血脂无明显影响,但对四氧嘧啶或链脲霉素引起的大鼠高血糖及蛋黄引起的小鼠高脂血症,高胆固醇饲料引起的大鼠高脂血症均有显著降低作用。本研究为降糖饮的应用提供了可靠的药理学依据。 相似文献
978.
Is colonic electrical activity a similar phenomena to small-bowel electrical activity? 总被引:4,自引:0,他引:4
Dr. José A. S. Medeiros M.D. Ph.D. Fausto A. Pontes M.D. Ph.D. Octávio A. R. O. Mesquita 《Diseases of the colon and rectum》1997,40(1):93-99
PURPOSE: This study was designed to investigate colonic spike bursts regarding 1) their migration behavior, 2) their pressure correlates, and 3) comparing colonic short spike bursts with spike bursts from migrating myoelectric complex from the small bowel. METHODS: Rectosigmoid electromyography and manometry were recorded simultaneously in seven normal volunteers and electromyography alone in five others during two hours of fasting and for two hours after one 2,100-kJ meal. One patient with an ileostomy was also studied by the same method to record the migrating myoelectric complex from the terminal ileum during fasting. RESULTS: Three kinds of spike bursts were observed in the pelvic colon: rhythmic short spike bursts, migrating long spike bursts, and nonmigrating long spike bursts. The meal significantly increased the number of migrating and nonmigrating long spike bursts (from 25 to 38.7 percent of the recording time;
P
<0.01). These bursts of potentials showed a peak 15 minutes after the meal, which may be caused by the gastrocolic reflex. Migrating long spike bursts started anywhere along the rectosigmoid and migrated from there aborad 82 percent of the time and orad or in both directions in 10 or 7 percent of the time, respectively. They originated pressure waves 99 percent of the time. Short spike bursts were more frequent before the meal (15.1 percent before and 9.6 percent after the meal), but the difference was not significant; they neither propagated nor initiated pressure waves detected by the miniballoon. CONCLUSIONS: Migrating long spike bursts were the only potentials that migrated, sometimes for short distances. Short spike bursts are a different phenomenon from the small-bowel migrating myoelectric complex because they do not migrate; they can occur during the postprandial period and never originated intraluminal pressure waves.Supported by a grant from the Instituto Nacional de Investigação Científica, Proc. DBI-22086.Presented at the meeting of the Portuguese Congress of Gastrenterology, Vila Moura, Portugal, June 2 to 5, 1993. 相似文献
979.
980.
Oral allergy syndrome induced by spinach 总被引:1,自引:1,他引:0
I. Sanchez F. Rodriguez J. L. Garcia-Abujeta L. Fernandez D. Quiñones D. Martin-Gil 《Allergy》1997,52(12):1245-1246