全文获取类型
收费全文 | 48338篇 |
免费 | 2944篇 |
国内免费 | 211篇 |
专业分类
耳鼻咽喉 | 686篇 |
儿科学 | 947篇 |
妇产科学 | 906篇 |
基础医学 | 6897篇 |
口腔科学 | 2641篇 |
临床医学 | 3991篇 |
内科学 | 10932篇 |
皮肤病学 | 949篇 |
神经病学 | 4457篇 |
特种医学 | 1410篇 |
外国民族医学 | 3篇 |
外科学 | 7238篇 |
综合类 | 217篇 |
一般理论 | 17篇 |
预防医学 | 3489篇 |
眼科学 | 796篇 |
药学 | 3394篇 |
中国医学 | 303篇 |
肿瘤学 | 2220篇 |
出版年
2023年 | 327篇 |
2022年 | 672篇 |
2021年 | 1246篇 |
2020年 | 790篇 |
2019年 | 1135篇 |
2018年 | 1438篇 |
2017年 | 1025篇 |
2016年 | 1102篇 |
2015年 | 1408篇 |
2014年 | 1813篇 |
2013年 | 2317篇 |
2012年 | 3519篇 |
2011年 | 3874篇 |
2010年 | 2145篇 |
2009年 | 1802篇 |
2008年 | 3007篇 |
2007年 | 3133篇 |
2006年 | 2834篇 |
2005年 | 2714篇 |
2004年 | 2519篇 |
2003年 | 2358篇 |
2002年 | 2219篇 |
2001年 | 703篇 |
2000年 | 623篇 |
1999年 | 639篇 |
1998年 | 484篇 |
1997年 | 406篇 |
1996年 | 324篇 |
1995年 | 333篇 |
1994年 | 285篇 |
1993年 | 276篇 |
1992年 | 380篇 |
1991年 | 310篇 |
1990年 | 270篇 |
1989年 | 281篇 |
1988年 | 228篇 |
1987年 | 229篇 |
1986年 | 223篇 |
1985年 | 182篇 |
1984年 | 177篇 |
1983年 | 167篇 |
1982年 | 151篇 |
1981年 | 121篇 |
1980年 | 131篇 |
1979年 | 127篇 |
1978年 | 91篇 |
1977年 | 95篇 |
1975年 | 88篇 |
1974年 | 70篇 |
1973年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Maria Fernanda Nince Ferreira Verônica Moraes Oliveira Priscila Vieira da Cunha Osmindo Rodrigues Pires Júnior 《Toxicon》2010,55(7):1255-1262
This study evaluated the effects of [D-Leu1]Microcystin-LR variants, by the exposure of Hypophthalmichthys molitrix to Microcystis aeruginosa NPLJ4. Fish was placed in aquariums and exposed to 105 cells mL−1. For 15 days, 05 individuals were removed every 05 days, and tissue samples of liver, skeletal muscle and intestinal tract were collected for histopathologic analyses. Following exposure, those surviving were placed in clean water for 15 days to evaluate their recovery. A control without toxins was maintained in the same conditions and exhibited normal histology and no tissue damage. In exposed fish, samples were characterized by serious damages that similarly affected the different organs, such as dissociation of cells, necrosis and haemorrhage. Samples showed signs of recovery but severe damages were still observed. The results should be valuable to analyze the potency of microcystin toxicity and to help in the diagnosis of fish deaths. 相似文献
102.
Thomas Rosemann Michel Wensing Katharina Joest Matthias Backenstrass Cornelia Mahler Joachim Szecsenyi 《BMC musculoskeletal disorders》2006,7(1):48-9
Background
Osteoarthritis (OA) is highly prevalent and has substantial impact on quality of life as well as on healthcare costs. The general practitioner (GP) often is the first care provider for patients with this chronic disease. The aim of this study was to identify health care needs of patients with OA and to reveal possible obstacles for improvements in primary care management of OA patients. 相似文献103.
Christelle Maillart Marie-Anne Schelstraete Michel Hupet 《J. Speech Lang. Hear. Res.》2004,47(1):187-198
The present research examined the quality of the phonological representations of French children with specific language impairment (SLI) and those with normal language development (NLD). Twenty-five children with SLI and 50 children with NLD matched on lexical age level participated in an auditory lexical decision task. The observations gathered in our study can be summarized as follows. First, children with a higher receptive lexical level performed better, and this was true both for children with NLD and children with SLI. Second, both children with NLD and those with SLI were more likely to reject pseudowords resulting from a modification affecting the number of syllables of a word than pseudowords resulting from a slight modification with the number of syllables unchanged. This difference, however, was greater for the children with SLI, who appeared to have much difficulty rejecting pseudowords resulting from slight modifications. Finally, the performance of children with SLI was particularly poor when presented with pseudowords resulting from a slight modification at the beginning or the end of a word. These findings are interpreted as supporting the hypothesis of an under-specification of phonological representations in children with SLI. 相似文献
104.
David M Spiegel Beverly Farmer Gerard Smits Michel Chonchol 《Journal of renal nutrition》2007,17(6):416-422
OBJECTIVE: This study was designed to evaluate the efficacy of magnesium carbonate as a phosphate binder in hemodialysis patients. DESIGN: This study was a prospective, randomized, open-label trial comparing magnesium carbonate/calcium carbonate versus calcium acetate as a sole phosphate binder. SETTING: This study involved outpatient hemodialysis. PARTICIPANTS: We recruited 30 stable hemodialysis patients without a history of frequent diarrhea. INTERVENTION: After receiving informed consent, we randomized patients 2:1 to magnesium carbonate versus calcium acetate. The dose of each binder was titrated to achieve the Kidney Disease Outcomes Quality Initiative (K/DOQI) phosphate target of <5.5 mg/dL. MAIN OUTCOME MEASURE: The efficacy-phase serum phosphorus concentration and the percentage of patients meeting K-DOQI targets for phosphorus, along with the daily elemental calcium intake, were the primary outcome measures. RESULTS: Magnesium carbonate provided equal control of serum phosphorus (70.6% of the magnebind group and 62.5% of the calcium acetate group had their average serum phosphorus within the K-DOQI target during the efficacy phase), while significantly reducing daily elemental calcium ingestion from phosphate binders (908 +/- 24 vs. 1743 +/- 37 mg/day, P < .0001). CONCLUSION: Magnesium carbonate was generally well-tolerated in this selected patient population, and was effective in controlling serum phosphorus while reducing elemental calcium ingestion. 相似文献
105.
Bertrand Marcheix Yoan Lamarche Pierre Perrault Raymond Cartier Denis Bouchard Michel Carrier Louis P. Perrault Philippe Demers 《European journal of cardio-thoracic surgery》2007,31(6):1004-1007
Objective: Whatever the surgical technique used, false aneurysm formation is one of the long-term complications of repair of aortic coarctation. Conservative management is associated with a 100% rate of rupture. The conventional surgical approach is complex and associated with high morbidity and mortality rates. We report our experience of endovascular management of pseudo-aneurysms after previous surgical repair of congenital aortic coarctation. Methods: Between October 2005 and 2006, stent-grafting of pseudo-aneurysms after previous surgical repair of congenital aortic coarctation was performed in four patients. Median age was 31.5 years (range: 24–38). Two patients had undergone two previous interventions. The last previous surgery consisted of graft interposition (N = 2), subclavian flap aortoplasty (N = 1) and aorto-aortic bypass (N = 1). Median size of the pseudo-aneurysm was 31.5 mm (range: 20–58). Mean time between the last surgery and endovascular treatment was 24 years (range: 3–32). One patient was treated emergently because of hemoptysis in relation with an aorto-bronchial fistula, the three other patients were treated electively. A transfemoral approach was used in all patients. The Zenith TX2® (Cook) thoracic stent-graft was used in all the patients, one patient underwent previous dilatation at the coarctation level. When present, the ostium of the left subclavian artery was always covered (N = 3). Results: No major complication occurred during the procedure and no patient died during the follow-up. One patient presented a type II endoleak which spontaneously healed during the first month. Another patient with his left subclavian artery covered presented claudication of the left arm requiring a carotid-subclavian bypass. After a median follow-up of 7.5 months (range: 1–12.9), the patients were asymptomatic and CT scans demonstrated complete exclusion of all treated postcoarctation aneurysms without recoarctation and without any stent-graft-related complication. Conclusions: The endovascular management of pseudo-aneurysms after previous surgical repair of congenital aortic coarctation is feasible. This approach was safe and effective. Long-term clinic and imaging follow-up is mandatory. 相似文献
106.
Joaquim Ferreira MD João Maia Silva MD Rita Freire BS João Pignatelli MD Leonor Correia Guedes MD Alexandra Feijó MD Mário Miguel Rosa MD Miguel Coelho MD João Costa MD Ana Noronha BS Russell Hewett MD A. Marques Gomes PhD J.L. Cirne de Castro MD Olivier Rascol PhD Cristina Sampaio PhD 《Movement disorders》2007,22(10):1471-1475
Our objective was to evaluate the frequency of neoplastic and preneoplastic skin lesions in Parkinson's disease (PD) patients when compared with an aged-matched population. We performed a cross-sectional survey in PD patients and in an age-matched control group. Patients and controls were examined by a movement disorder specialist and a dermatologist. 150 PD patients and 146 controls were included. Thirty-five PD patients (23.3%) presented skin lesions that could be classified as neoplastic or preneoplastic vs. 20 subjects in the control group (13.7%) (OR 95%, CI 1.92 [1.05, 3.51]). However, this difference lost statistical significance when adjusted for gender (recruitment of controls was matched just for age with an over representation of males in the PD group). Twenty-nine PD patients (19%) presented actinic keratosis and basal cell carcinoma was diagnosed in 4 patients (3%). Although nonconclusive, our results are in agreement with previous studies suggesting an increased risk of skin cancer in PD patients. The frequency of actinic keratosis in PD patients and the associated risk to develop melanoma recommends its screening in future epidemiological studies. 相似文献
107.
Marcos Barbosa-Ferreira Maria Lúcia Zaidan Dagli Paulo César Maiorka Silvana Lima Górniak 《Food and chemical toxicology》2005,43(4):497-503
Senna occidentalis (So) is a weed that grows in pastures along fences and in fields cultivated with cereals such as corn and soybean, and many reports have been showing intoxication with this plant in different animal species. It is also used in many medicinal purposes. The objective of the present study was to better evaluate the toxic effects of prolonged administration of So seeds to rats. Forty male Wistar rats were divided into four groups of 10 animals each, three of them respectively fed rations containing 1%, 2% and 4% So seeds, and the last one (control) fed commercial ration for a period of 2 weeks. Fourteen rats were also used in a pair-feeding (PF) experiment. The rats of the experimental groups showed lethargy, weakness, recumbency, depression and emaciation. Two rats of the 4% group and two of the PF group died during the experiment. Histopathological study showed fiber degenerations in the skeletal (Tibial, pectoral and diaphragm) and cardiac muscles. In the liver parenchyma, was observed vacuolar degeneration and, in the kidney, mild nefrosis in the proximal convoluted tubules. All of these alterations occurred in a dose-dependent fashion. Moderate to severe degeneration and spongiosis in the central nervous system, especially in cerebellum. Electron microscopy revealed mitochondrial lesions in all analyzed tissues. 相似文献
108.
Ana Teresa Timóteo Andreia Mamede Maria de Lurdes Ferreira José Serra José Alberto Oliveira Rui Cruz Ferreira Jorge Quininha 《Revista portuguesa de cardiologia》2007,26(2):135-143
BACKGROUND: Nitrate therapy can induce ischemic preconditioning with a consequent increase in tolerance to ischemia. In the context of acute coronary syndromes (ACS), nitrates may result in a different presentation. with greater protection. OBJECTIVES: To investigate in a population of patients with ACS whether previous chronic use of nitrates results in a different presentation of ACS. METHODS: We studied 287 patients (65 +/- 13 years, 66% male) admitted to our department in the first six months of 2005 with ACS (with and without ST-segment elevation). Of these, 8% were under nitrate therapy at the time of admission. In this group, 27% presented ACS without ST-segment elevation, while in the group without nitrates this value was 58% (p = 0.005). By univariate analysis, the use of nitrates was a predictor of the preferential occurrence of non-ST-segment elevation ACS (OR 0.27, 95% CI 0.10-0.71). After correction for the potential influence of variables (age, gender, previous revascularization and smoking) by multivariate logistic regression, nitrate therapy remained a borderline predictor of clinical presentation as non-ST-segment elevation ACS (OR 0.37, 95% CI 0.13-1.04, p = 0.059). CONCLUSIONS: Previous use of nitrates was associated with a tendency to present as non-ST-segment elevation ACS. This finding may be explained by the hypothesis that nitrates induce pharmacological preconditioning, reducing the transmural extent of myocardial infarction. 相似文献
109.
Luzitano Brando Ferreira Celso Teixeira Mendes Cludia Emília Vieira Wiezel Marcelo Rizzatti Luizon Aguinaldo Luiz Simes 《American journal of human biology》2006,18(5):702-705
Allelic frequencies of eight autosomal short‐tandem repeat (STR) loci (TH01, TPOx, CSF1PO, vWA, FES/FPS, F13A1, F13B, and CD4) were determined in 400 individuals born in the State of São Paulo. No significant deviations from Hardy‐Weinberg equilibrium were found in any loci analyzed. The Unweighted Pair‐Group Method with Arithmetic Mean (UPGMA) tree constructed based on genetic distances revealed that the present population was grouped with Europeans, and separated from African and Amerindian populations. Estimates of admixture components based on the gene identity method revealed 79% European, 14% African, and 7% Amerindian contributions to this Brazilian population sample. Am. J. Hum. Biol. 18:702–705, 2006. © 2006 Wiley‐Liss, Inc. 相似文献
110.
M Ferreira L Lanziotti M Monteiro G Abuhadba L F Capotorto L Nolte N Fearnot 《European journal of vascular and endovascular surgery》2007,34(6):702-708
PURPOSE: Since long-term patency and device integrity of nitinol stents in SFA lesions are not well studied, we examined clinical outcome, patency and device integrity after stenting long lesions using a standardized implantation technique. METHODS: Between 2001 and 2006, 59 patients (74 lesions) were treated with the same nitinol self-expandable stent (Zilver, Cook, USA) and technique for SFA recanalization. Clinical charts and imaging were retrospectively reviewed for patency (primary and assisted-primary), and device integrity. RESULTS: Patients were 74.5 (10.9) years old (range 49 to 93), 64% male, 42% diabetic, 62% hypertensive and 67% current or former smokers. Lesions were 23% TASC B, 16% TASC C, or 61% TASC D. Mean recanalization length was 19 cm (range 3 to 53). Mean number of stents per patient was 2.8 (total 210). Mean follow-up time was 2.4 years (range 3 days to 4.8 years). Kaplan-Meier estimates for primary patency rates were 90%, 78%, 74%, 69%, and 69% at 1, 2, 3, 4 and 4.8 years, respectively. Ten restenoses at a mean of 500 (388) days (1-1251 days) were successfully recanalized. The assisted primary patency rates were 96%, 90%, 90%, 90% and 90% at 1, 2, 3, 4 and 5 years, respectively. Six complete occlusions could not be reverted by a second recanalization procedure, and were treated by surgical bypass (1 case), amputation (3 cases), or medical management (2 cases). One (1.04%) Class II stent fracture was noted. CONCLUSIONS: SFA recanalization with a standardized implantation technique and nitinol stents provides good long-term primary and assisted-primary patency. 相似文献