全文获取类型
收费全文 | 1410853篇 |
免费 | 113535篇 |
国内免费 | 3332篇 |
专业分类
耳鼻咽喉 | 18374篇 |
儿科学 | 46548篇 |
妇产科学 | 41044篇 |
基础医学 | 200735篇 |
口腔科学 | 37694篇 |
临床医学 | 125998篇 |
内科学 | 284394篇 |
皮肤病学 | 33353篇 |
神经病学 | 116875篇 |
特种医学 | 53989篇 |
外国民族医学 | 464篇 |
外科学 | 210496篇 |
综合类 | 32761篇 |
现状与发展 | 3篇 |
一般理论 | 487篇 |
预防医学 | 110000篇 |
眼科学 | 31497篇 |
药学 | 98499篇 |
1篇 | |
中国医学 | 3348篇 |
肿瘤学 | 81160篇 |
出版年
2021年 | 10843篇 |
2019年 | 11663篇 |
2018年 | 16569篇 |
2017年 | 12667篇 |
2016年 | 14257篇 |
2015年 | 16004篇 |
2014年 | 22556篇 |
2013年 | 33390篇 |
2012年 | 45377篇 |
2011年 | 47922篇 |
2010年 | 28157篇 |
2009年 | 27050篇 |
2008年 | 44319篇 |
2007年 | 46826篇 |
2006年 | 47399篇 |
2005年 | 45867篇 |
2004年 | 43753篇 |
2003年 | 41697篇 |
2002年 | 40194篇 |
2001年 | 73003篇 |
2000年 | 74534篇 |
1999年 | 61575篇 |
1998年 | 16990篇 |
1997年 | 15435篇 |
1996年 | 15590篇 |
1995年 | 14795篇 |
1994年 | 13402篇 |
1993年 | 12588篇 |
1992年 | 45854篇 |
1991年 | 43494篇 |
1990年 | 41510篇 |
1989年 | 39562篇 |
1988年 | 36184篇 |
1987年 | 35356篇 |
1986年 | 32862篇 |
1985年 | 31288篇 |
1984年 | 23829篇 |
1983年 | 20027篇 |
1982年 | 12212篇 |
1981年 | 10786篇 |
1979年 | 20701篇 |
1978年 | 14582篇 |
1977年 | 12086篇 |
1976年 | 11367篇 |
1975年 | 11622篇 |
1974年 | 13989篇 |
1973年 | 13533篇 |
1972年 | 12634篇 |
1971年 | 11469篇 |
1970年 | 10910篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Geir Håland Kai-Håkon Carlsen Chandra Sekhar Devulapalli Morten Pettersen Petter Mowinckel Karin C. Lødrup Carlsen 《Pediatric allergy and immunology》2007,18(6):528-534
The aim of the study was to assess if lung function at birth predicts lung function at 2 yr and secondly, if lung function development was influenced by the common phenotypes of recurrent bronchial obstruction (rBO) or atopic eczema (AE) by 2 yr. Lung function was assessed at birth (n = 802) and at 2 yr within the prospective birth cohort study 'the Environment and Childhood Asthma Study' in Oslo. The 135 children with lung function measured at birth by tidal flow volume (TFV) loops and passive respiratory mechanics, who were included in a nested case-control study were reinvestigated at 2 yr with clinical examination, TFV loops (n = 90) (mean age 26.6 (3.7 s.d.) months), skin prick test and parental interview. Children were categorized into quartiles (lower, middle two, upper) according to time to peak tidal expiratory flow/total expiratory time (t(PTEF)/t(E)) at birth as well as clinical phenotype based on the presence of rBO and/or AE (ever) by 2 yr. The observed reduction in mean t(PTEF)/t(E) from birth to 2 yr within the quartiles, were not significantly different after controlling for 'regression to the mean'. t(PTEF)/t(E) at birth correlated significantly with t(PTEF)/t(E) at 2 yr, (r = 0.475, p < 0.001). Children with both rBO and AE by 2 yr had significantly lower t(PTEF)/t(E) at 2 yr (p = 0.002) and at birth (p = 0.027), compared with children with no rBO or AE. Clinical phenotype at 2 yr did not influence the change in t(PTEF)/t(E) from birth to 2 yr. This study demonstrates a clear tracking of lung function from birth, not influenced by rBO or AE by 2 yr. 相似文献
992.
Scalp electrical recording during paralysis: quantitative evidence that EEG frequencies above 20 Hz are contaminated by EMG. 总被引:2,自引:0,他引:2
Emma M Whitham Kenneth J Pope Sean P Fitzgibbon Trent Lewis C Richard Clark Stephen Loveless Marita Broberg Angus Wallace Dylan DeLosAngeles Peter Lillie Andrew Hardy Rik Fronsko Alyson Pulbrook John O Willoughby 《Clinical neurophysiology》2007,118(8):1877-1888
OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation. 相似文献
993.
994.
Presented in this work is a rare injury of a blunt abdominal trauma in a child. Besides a partial rupture of the kidney and a retro-/intraperitoneal haematoma, a further injury occurred from the accident: an initially clinically indetectable tear of the A. iliaca communis which was found intraoperatively and with systematic CT analysis. Traumatic blood vessel lesions of the abdominal aorta and in particular the iliac blood vessels are very rare in children. By such violent impact injuries, it is therefore vital to perform a clinical examination of the foot pulse, systematic analysis of radiology diagnostics, and intraoperative exploration. The growth phase should be considered for therapy of the blood vessels depending on the child's age group. As the long-term results of graft implants are practically unknown, if possible a primary suture or vein patch should be performed. 相似文献
995.
996.
E Gadelha Figueiredo M Castillo De la Cruz N Theodore P Deshmukh M C Preul 《Minimally invasive neurosurgery》2006,49(1):37-42
We describe a modified keyhole laminoforaminotomy (LF) using anatomic landmarks on the posterior aspect of the cervical vertebral body to decompress the intervertebral foramen with minimal bone removal. Twenty-four procedures were performed at C3-4, C4-5, and C5-6; 12 at C6-7; and 3 at C7-Tl. Facets and laminae structures were identified based on relative surgical perspectives. Bony resection was limited as follows: 1) inferior limit; inferior border of the superior facet; 2) superior limit, superior border of the superior facet; 3) lateral limit, a vertical line linking the junction of the lamina-facet to the lateral end of the superior limit; and 4) lateral aspect of the dural sac. Fluoroscopy was used to confirm that the intervertebral space was reached. The amount of bony removal was quantified for the superior and inferior laminae and facets. The length of the exposed nerve root was measured. The intervertebral foramen was exposed and the intervertebral disc reached in all specimens. Fluoroscopy showed that the center of the exposure remained at the same height with the intervertebral space. The mean length of the nerve root was 4.6 mm; the mean percentage of bony resection was 21.8%, 7.5%, 11.3%, and 11.5% for the superior and inferior laminae and facets, respectively. Opening the intervertebral foramen posteriorly consistently exposed sufficient nerve root length and allowed access to the intervertebral disc. The technique offers the most direct and safest method of decompressing the intervertebral foramen while minimizing bony resection. This simple surgical procedure may help reduce postoperative morbidity. 相似文献
997.
Structure-activity relationship (SAR) between some natural flavonoids and ocular blood flow in the rabbit. 总被引:1,自引:0,他引:1
PURPOSE: Flavonoids with two to five hydroxy groups, with or without sugar, and/or methoxy groups were studied on their effects to affect ocular blood flow. METHODS: Colored microsphere technique was used to determine the ocular blood flow in rabbit eyes. RESULTS: Flavonoids with three free hydroxy (OH) groups seemed to produce the optimal effects in increasing ocular blood flow (naringenin and hesperitin, Pfalts and Bauer, Waterbury, CT). Whether the OH groups are below three (naringenin, hesperitin, Pfalts and Bauer, Waterbury, CT) or above four (Quercetin, Pfalts and Bauer, Waterbury, CT), they produced no effects on the ocular blood flow. When OH groups are four (rutin, Aldrich, Milwaukee, WI), it produced mixed effects on ocular blood flow. The attachment of rutinose and/or methoxy group in the structure did not affect the ocular blood flow one way or the other. CONCLUSION: The ocular blood flow is increased significantly by the number of OH group in the molecule, with three the best to increase the ocular blood flow. 相似文献
998.
999.
1000.