全文获取类型
收费全文 | 178313篇 |
免费 | 8703篇 |
国内免费 | 533篇 |
专业分类
耳鼻咽喉 | 2473篇 |
儿科学 | 5739篇 |
妇产科学 | 4843篇 |
基础医学 | 24731篇 |
口腔科学 | 4798篇 |
临床医学 | 12155篇 |
内科学 | 40867篇 |
皮肤病学 | 5786篇 |
神经病学 | 14949篇 |
特种医学 | 4111篇 |
外国民族医学 | 31篇 |
外科学 | 22334篇 |
综合类 | 900篇 |
一般理论 | 44篇 |
预防医学 | 18195篇 |
眼科学 | 3639篇 |
药学 | 12873篇 |
中国医学 | 563篇 |
肿瘤学 | 8518篇 |
出版年
2023年 | 1038篇 |
2022年 | 1942篇 |
2021年 | 4286篇 |
2020年 | 2218篇 |
2019年 | 4012篇 |
2018年 | 5362篇 |
2017年 | 3408篇 |
2016年 | 3496篇 |
2015年 | 3886篇 |
2014年 | 5069篇 |
2013年 | 7401篇 |
2012年 | 10999篇 |
2011年 | 11361篇 |
2010年 | 6307篇 |
2009年 | 5369篇 |
2008年 | 9192篇 |
2007年 | 9614篇 |
2006年 | 9314篇 |
2005年 | 9291篇 |
2004年 | 8586篇 |
2003年 | 7954篇 |
2002年 | 7619篇 |
2001年 | 5330篇 |
2000年 | 5472篇 |
1999年 | 4588篇 |
1998年 | 1326篇 |
1997年 | 956篇 |
1996年 | 885篇 |
1995年 | 748篇 |
1994年 | 637篇 |
1992年 | 2280篇 |
1991年 | 2163篇 |
1990年 | 2020篇 |
1989年 | 1765篇 |
1988年 | 1616篇 |
1987年 | 1587篇 |
1986年 | 1473篇 |
1985年 | 1408篇 |
1984年 | 1045篇 |
1983年 | 899篇 |
1979年 | 1014篇 |
1978年 | 674篇 |
1975年 | 684篇 |
1974年 | 895篇 |
1973年 | 865篇 |
1972年 | 748篇 |
1971年 | 699篇 |
1970年 | 749篇 |
1969年 | 709篇 |
1968年 | 673篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Rènée du Toit Katherine Soong Garry Brian Jacqueline Ramke 《Optometry and vision science》2006,83(8):582-588
PURPOSE: The advantages of a focometer (FOCOMETER) over other methods of refraction for use in developing countries are that it is lightweight, compact, relatively inexpensive, fairly quick, and easy to use with minimal training. This clinical trial compared the repeatability, validity, and ease of use of the focometer with an autorefractor. METHODS: The refractive status of the right eye of 80 participants was determined with an autorefractor (Canon RK3). Three measurements were also taken with the focometer. RESULTS: The spherical equivalent (M) of the focometer was 0.25 D more positive than the autorefractor (p < 0.001) and 84% of measurements were within 0.75 D of the autorefractor. The autorefractor detected astigmatism in 91% (73) of the eyes, whereas the focometer identified only 32% (26). The design of the clock target restricts cylinder axis accuracy to the nearest 15 degrees . There was evidence of a learning effect for the focometer: the second and third measurements were more repeatable in the untrained group. There were no differences between the mean (1.03 +/- 2.28) and third focometer (-1.05 +/- 2.32) measurements (p = 0.34). However, using the third focometer measurement, 94% of participants had visual acuities of at least 6/12(-2). CONCLUSIONS: This study highlighted the focometer's restricted power range, inaccuracy of astigmatism and axis determination, and dependence on subject understanding and compliance. Therefore, in most clinical settings, the focometer would not be adequate for quantifying refractive error, but the focometer spherical equivalent was within acceptable limits of the autorefractor, and the visual acuity with lenses determined by the focometer indicates its potential usefulness in public health settings, especially where only spherical ready-made spectacles are dispensed. There may be more cost-effective ways to determine refractive error in these circumstances. A potentially important enhancement in focometer methodology that improves its ease of use was identified: use only the third measurement for each eye. 相似文献
132.
Magdalena Cortes Alessandro Lambiase Marta Sacchetti Silvia Aronni Stefano Bonini 陈旭 《美国医学会眼科杂志(中文版)》2006,18(1):30-32
泪管-耳-牙-指(趾)(LADD)综合征是一种具有多种表现的常染色体显性遗传疾病。最初在1967年由Levy报道。1例双侧泪液系统缺失、杯状耳、干嘴,以及牙、手臂和指(趾)异常的单发病例。之后一些新发现的临床表现,如肾脏异常、唾液腺缺乏、先天性髋脱位、先天性裂孔疝和横膈疝、感觉性耳聋和传导性耳聋、牙发育不全、四肢异常、口腔干燥和眼干都被报道与此综合征有关。 相似文献
133.
Benedita Sampaio-Maia Mónica Moreira-Rodrigues Paula Serr?o Manuel Pestana 《Nephrology, dialysis, transplantation》2006,21(2):314-323
BACKGROUND: A primary tubular sodium handling abnormality has been implicated in the edema formation of nephrotic syndrome. Dopamine synthesized by renal proximal tubules behaves as an endogenous natriuretic hormone by activating D(1)-like receptors as a paracrine/autocrine substance. METHODS: We examined the time courses of the urinary excretion of sodium, protein and dopamine in puromycin aminonucleoside (PAN)-treated and control rats. The rats were sacrificed during greatest sodium retention (day 7) as well as during negative sodium balance (day 14) for the evaluation of renal aromatic l-amino acid decarboxylase (AADC) activity, the enzyme responsible for the synthesis of renal dopamine. Also, the influence of volume expansion (VE) and the effects of the D(1)-like agonist fenoldopam (10 microg/kg bw/min) on natriuresis and on proximal tubular Na(+),K(+)-ATPase activity were examined on day 7. RESULTS: The daily urinary excretion of dopamine was decreased in PAN-treated rats, from day 5 and beyond. This was accompanied by a marked decrease in the renal AADC activity, on days 7 and 14. During VE, the fenoldopam-induced decrease in proximal tubular Na(+),K(+)-ATPase activity was more pronounced in PAN-treated rats than in controls. However, the urinary sodium excretion during fenoldopam infusion was markedly increased in control rats but was not altered in PAN-treated animals. CONCLUSION: PAN nephrosis is associated with a blunted renal dopaminergic system activity which may contribute to enhance the proximal tubular Na(+),K(+)-ATPase activity. However, the lack of renal dopamine appears not to be related with the overall renal sodium retention in a state of proteinuria. 相似文献
134.
Successful efforts in improving breastfeeding initiation rates at an urban teaching hospital prompted the hospital to create a lactation consultant (LC) position in the outpatient setting to focus on breastfeeding duration. This article reviews the complexity of the clinic setting, with the challenges and benefits of the consultant's first year in one of the hospital's outpatient clinics. Preliminary data collected by the consultant suggest that patients counseled by the LC in the outpatient clinic setting have longer breastfeeding duration rates. 相似文献
135.
A. G. G. Lødeng C. Ahlén H. Lysvand L. H. Mandal O. J. Iversen 《Clinical microbiology and infection》2006,12(8):761-768
This report describes a new PCR-based assay for the detection of Pseudomonas aeruginosa genotype D in occupational saturation diving systems in the North Sea. This genotype has persisted in these systems for 11 years (1993-2003) and represents 18% of isolates from infections analysed during this period. The new PCR assay was based on sequences obtained after randomly amplified polymorphic DNA (RAPD)-PCR analysis of a group of isolates related to diving that had been identified previously by pulsed-field gel electrophoresis (PFGE). The primer set for the D genotype targets a gene that codes for a hypothetical class 4 protein in the P. aeruginosa PAO1 genome. A primer set able to detect P. aeruginosa at the species level was also designed, based on the 23S-5S rDNA spacer region. The two assays produced 382-bp and 192-bp amplicons, respectively. The PCR assay was evaluated by analysing 100 P. aeruginosa isolates related to diving, representing 28 PFGE genotypes, and 38 clinical and community P. aeruginosa isolates and strains from other species. The assay identified all of the genotype D isolates tested. Two additional diving-relevant genotypes (TP2 and TP27) were also identified, as well as three isolates of non-diving origin. It was concluded that the new PCR assay is a useful tool for early detection and prevention of infections with the D genotype. 相似文献
136.
Yaprak Engin-Ustün Yusuf Ustün M Mutlu Meydanli Ay?e Kafkasli 《Gynecological endocrinology》2006,22(12):676-679
AIM: To compare the effects of 17beta-estradiol given intranasally (intranasal E2) and raloxifene on serum lipid profile and fibrinogen in hypercholesterolemic postmenopausal women. METHODS: The study population consisted of 46 women after menopause. The placebo group (n = 11) was given calcium, while the intervention groups were given intranasal E2 (Aerodiol; Servier, Chambray-les-Tours, France) (n = 16) or raloxifene (Evista; Lilly SA, Madrid, Spain) (n = 19). Blood lipids and fibrinogen were compared between groups at baseline and after 3 months of treatment. RESULTS: The group receiving intranasal E2 showed a significant decrease in triglyceride levels (p<0.05) and a marked increase in high-density lipoprotein cholesterol levels (p<0.05). No changes in lipid profile were observed in the raloxifene and placebo groups. Raloxifene caused a significant decrease in fibrinogen levels (p<0.05). CONCLUSION: Intranasal E2 exerts significant effects on lipid profile in hypercholesterolemic postmenopausal women. Raloxifene has a greater impact on fibrinogen than intranasal E2 application. 相似文献
137.
Gábor Márk Somfai Kata Miháltz Eszter Tulassay János Rigó 《Hypertension in pregnancy》2006,25(1):11-20
OBJECTIVE: Visual symptoms are common in patients with preeclampsia, and are caused by various underlying pathological changes in the retina. Blurred vision may be one of these symptoms. We describe three cases in which the underlying retinal pathology of blurred vision was clarified using optical coherence tomography (OCT), a novel, non-invasive ophthalmic imaging technique that provides micrometer-scale resolution images of the human retina. METHODS: Three patients with preeclampsia complained of blurred vision postpartum. In all cases, ophthalmoscopy was performed at the bedside, followed by the assessment of best corrected visual acuity, slit-lamp biomicroscopy, fluorescein angiography (FLA), and OCT. In all cases, the presence of central visual defects was examined by an Amsler-grid. RESULTS: In one case, the symptoms were bilateral. In all affected eyes, the patients complained of a relative central scotoma. Ophthalmoscopy showed edema in the affected maculae, while OCT examination clarified a serous neurosensory detachment of the macula. In one case, a neurosensory detachment was also detected in the papillomacular region of a fellow eye with no symptoms. In two cases, FLA was performed, but only in one case could we detect late leakage and subretinal exudates. The serous detachments observed showed total resolution in all cases within 5 to 10 weeks, with restoration of visual acuity. CONCLUSION: In patients with preeclampsia, OCT may provide a useful method for the precise assessment of retinal changes, distinguishing retinal edema from serous neurosensory detachments. This finding may help to clarify the pathophysiological circulatory changes seen in preeclampsia. 相似文献
138.
Indices of surgical site infection risk and prediction of other adverse outcomes during hospitalization. 总被引:2,自引:0,他引:2
Miguel Delgado-Rodríguez Silvia Palma Antonio Gómez-Ortega Gabriel Martínez-Gallego Marcelino Medina-Cuadros 《Infection control and hospital epidemiology》2006,27(8):825-828
OBJECTIVE: To assess which adverse postsurgical outcomes are best predicted by the Study on the Efficacy of Nosocomial Infection Control (SENIC) index and the National Nosocomial Infection Surveillance system (NNIS) index. DESIGN: Prospective cohort study. SETTING: The service of general surgery at a tertiary care hospital. PATIENTS: A consecutive series of patients hospitalized for more than 1 day (n=2,989). RESULTS: The outcome best predicted by the SENIC and NNIS indices was assessed by estimating the area under the receiver operating characteristic (ROC) curve. The areas under the ROC curves for nosocomial infection and in-hospital death were higher for the NNIS index than they were for the SENIC index (P<.05). The NNIS index predicted in-hospital death better than it predicted surgical site infection (area under the ROC curve+/-SE, 0.836+/-0.022 vs 0.689+/-0.017; P=.001). CONCLUSIONS: The NNIS index is superior to the SENIC index for all adverse postsurgical outcomes. Its ability to predict in-hospital mortality is clearly better than its ability to predict surgical site infection. 相似文献
139.
The differences between the postprandial mixing or propulsion and the interdigestive motility of the gastrointestinal (GI)
tract are already known. Earlier studies showed dose-dependent differences in the effects of erythromycin on interdigestive
motility. The various GI side-effects (vomiting, diarrhoea) also suggest that there are different effects of erythromycin
on the GI motility. The aim of our study was to examine postprandially the propulsive effects of different doses of erythromycin
on the movement of intraluminal contents in the upper GI tract of the rat. The animals were fasted for 24 h before the experiments
but water was given freely. The rats received 1.5 ml 1.5% methylcellulose painted with 0.05% phenol-red intragastrically (test
solution). Erythromycin(E. lactobionate) was given intravenously at doses of 0.05, 0.1, 0.25, 0.5, 1.0 and 5.0 mg/kg 15 min before the administration of a test solution.
The animals were sacrificed 20,60 and 120 min after administration of methylcellulose, when the distance between the front
of the painted intraluminal contents and the pylorus was measured and expressed as a percentage of the total length of small
intestine. The phenol-red content in the stomach and small intestine was measured spectrophotometrically and the gastric emptying
was calculated from the ratio of the measured total and intestinal phenol-red content. Our results showed that the small doses
of erythromycin (0.1 and 0.25 mg/kg) accelerated gastric emptying after 20 min but did not change significantly the propulsive
motility of upper small intestine; however, large doses of erythromycin (1.0 and 5.0 mg/kg) decreased gastric emptying and
upper GI motility after 20 and 60 min. In summary, the prokinetic action of small doses of erythromycin was demonstrated,
but its effecttime on GI motility is short and the ratio of the stimulating and inhibitory doses is 1:10.
This paper was presented at the Section of IUPHAR GI Pharmacology Symposium on ’Biochemical pharmacology as an approach to
gastrointestinal disorders (basic science to clinical perspectives)‘, October 12-14, 1995, Pécs, Hungary. 相似文献
140.
K. Sjölund S. Fasth R. Ekman L. Hultén H. Jiborn S. Nordgren & F. Sundler 《Neurogastroenterology and motility》1997,9(3):143-150
Tissue specimens from the large bowel of 18 patients with long-standing slow transit constipation were investigated to determine the distribution and density of several neuropeptides and amines in the enteric nerve system, and also of endocrine cells in comparison to normal individuals. CGRP (calcitonin gene-related peptide), galanin, glucagon, GRP (gastrin-releasing peptide), metenkephalin, motilin, neuropeptide Y (NPY), PACAP, peptide YY (PYY), serotonin, somatostatin, substance P and VIP were studied by immunohistochemistry. Tissue concentrations of VIP, substance P and galanin were also measured by radioimmunoassay. Significantly increased VIP, SP and galanin contents were found in specimens from the ascending colon. Levels of VIP and galanin were also increased in the transverse colon. Immunohistochemistry revealed only marginal changes with an increased density of PACAP nerve fibres in the smooth muscle and of VIP and PACAP nerves in the myenteric plexus of the transverse colon. In the descending colon substance P and NPY immunoreactivity were also increased in the myenteric plexus while the density of VIP nerve fibres was reduced in the mucosa/submucosa. The frequency of PYY-containing cells and the 5-HT-containing cells in the ascending colon was significantly increased in the constipated patients. 相似文献