全文获取类型
收费全文 | 255817篇 |
免费 | 18118篇 |
国内免费 | 1138篇 |
专业分类
耳鼻咽喉 | 2862篇 |
儿科学 | 6592篇 |
妇产科学 | 4658篇 |
基础医学 | 33517篇 |
口腔科学 | 4636篇 |
临床医学 | 25820篇 |
内科学 | 54490篇 |
皮肤病学 | 3408篇 |
神经病学 | 24621篇 |
特种医学 | 8694篇 |
外国民族医学 | 11篇 |
外科学 | 38819篇 |
综合类 | 3507篇 |
一般理论 | 319篇 |
预防医学 | 21709篇 |
眼科学 | 6613篇 |
药学 | 17192篇 |
6篇 | |
中国医学 | 366篇 |
肿瘤学 | 17233篇 |
出版年
2023年 | 1356篇 |
2022年 | 2436篇 |
2021年 | 5477篇 |
2020年 | 3289篇 |
2019年 | 5352篇 |
2018年 | 6012篇 |
2017年 | 4522篇 |
2016年 | 5007篇 |
2015年 | 5900篇 |
2014年 | 8691篇 |
2013年 | 11899篇 |
2012年 | 18152篇 |
2011年 | 19065篇 |
2010年 | 10669篇 |
2009年 | 9531篇 |
2008年 | 16772篇 |
2007年 | 17617篇 |
2006年 | 17484篇 |
2005年 | 17456篇 |
2004年 | 16364篇 |
2003年 | 15190篇 |
2002年 | 14176篇 |
2001年 | 2278篇 |
2000年 | 1735篇 |
1999年 | 2437篇 |
1998年 | 3122篇 |
1997年 | 2597篇 |
1996年 | 2235篇 |
1995年 | 2130篇 |
1994年 | 1777篇 |
1993年 | 1601篇 |
1992年 | 1334篇 |
1991年 | 1243篇 |
1990年 | 1092篇 |
1989年 | 1050篇 |
1988年 | 1032篇 |
1987年 | 1021篇 |
1986年 | 1005篇 |
1985年 | 1035篇 |
1984年 | 1260篇 |
1983年 | 1166篇 |
1982年 | 1392篇 |
1981年 | 1332篇 |
1980年 | 1164篇 |
1979年 | 730篇 |
1978年 | 777篇 |
1977年 | 662篇 |
1976年 | 608篇 |
1975年 | 494篇 |
1974年 | 513篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Douglas N. Johnson Herbert J. Weingartner Paul Andreason David T. George 《Psychopharmacology》1995,121(2):145-149
This study explored whether benzodiazepines selectively affect aspects of attention and/or visual information processing, as they do memory. A cued visual-search paradigm was employed, using normal volunteers and a single dose of triazolam. This paradigm provided for a detailed examination of two aspects of visual attention and information processing: 1) controlled versus automatic attention allocation (via central and peripheral cues), and 2) the extent to which processing an item in a non-cued location affects performance (via cue-validity). Triazolam, compared to placebo, significantly increased response time, and Drug Condition interacted with Cue-Validity but not Cue-Type. Based on these data, we argue that triazolam doesnot affect attention allocation butdoes affect attentional disengagement and/or attention switching mechanisms. 相似文献
942.
Interobserver variability in neonatal cranial ultrasonography 总被引:1,自引:0,他引:1
Jennifer Pinto Nigel Paneth Elias Kazam Ram Kairam Sylvan Wallenstein Walter Rose David Rosenfeld Steven Schonfeld Irving Stein Thomas Witomski 《Paediatric and perinatal epidemiology》1988,2(1):43-58
The reliability of cranial ultrasound diagnosis in the premature neonate was examined using data from an ongoing multicentre study of the epidemiology and long-term consequences of neonatal brain haemorrhage. First week ultrasound films (obtained at 4 hours, 24 hours and 7 days) from 60 study subjects were randomly selected for independent review by two groups of experienced interpreters, and results were recorded separately for observations (i.e. presence or absence of an abnormal echodense area on a film) and interpretations (i.e. presence or absence of haemorrhage or ventricular dilatation) in each hemisphere. Because of deaths in the first week of life, the total number of films examined was 138. Concordance on the presence or absence of an abnormal echodensity was examined for each individual film for three areas of interest: the germinal matrix, the ventricles and the parenchyma. Concordance on the presence or absence of haemorrhage or ventricular dilatation was examined only for the seventh-day film, or the final film prior to death. Finally, concordance was analysed with the diagnostic interpretations grouped into categories thought to differ prognostically for long-term outcome. In general, concordance was poorest for germinal matrix lesions and best for parenchymal lesions. Concordance was lower for observations made on each individual film than it was for interpretation of the final film in each case. Fifty-five of 60 cases (92%) were assigned to the same major prognostic category by both readers. Ultrasound review conferences were held periodically and there was evidence that concordance in ultrasound reading and interpretation improved during the course of the study. 相似文献
943.
David B. Sanford M. D. Anita Yeomans-Kinney R. N. Peter W. McLaughlin M. D. Gabriel N. Hortobagyi M. D. Kapil Dhingra M. D. 《The breast journal》1996,2(5):312-319
Abstract: We performed a retrospective analysis of clinical course of 91 patients who developed both breast cancer and a chronic lymphoproliferative neoplasm and were seen at the M. D. Anderson Cancer Center between January 1, 1970 and December 30, 1991. The sample included 24 individuals who developed lymphoproliferative neoplasm first (Group A), 22 individuals with concurrent diagnosis of both malignancies (Group B), and 45 individuals who developed breast cancer first (Group C). The median time to diagnosis of secondary breast cancer and lymphoproliferative neoplasm was 66 months (range, 7–459) and 65 months (range, 0–334), respectively. A higher proportion of Group B lymphomas were low-grade (77% vs. 47% [Group A] vs. 37% [Group C] p = 0.009). Prior occurrence of either one of these malignancies did not affect the disease-specific survival from the second malignancy. However, continuing mortality from the first malignancy appeared to contribute to a poor overall survival following second malignancy. Group A included 8 patients who developed breast cancer following radiation therapy for Hodgkin's disease after a mean interval of 18 (± 4.3) years. Three of these individuals had coexisting ductal and lobular histology (vs. none of the individuals in Groups B and C, p = 0.02). Another interesting finding was the high incidence of multiple additional malignancies in this patient population. A total of 29 additional neoplasms occurred in 21 (23%) of the 91 study subjects. These malignancies involved a wide variety of organ sites and could not be attributed to the therapy for either the breast cancer or the lymphoma in most cases. The data suggest that individuals who develop both breast cancer and a lymphoproliferative neoplasm are at a high risk for multiple malignancies. Close surveillance of such individuals for additional malignancies and further studies to understand the molecular basis of this predisposition are warranted.? 相似文献
944.
Harold B. Canning DDS David E. Frost DDS MS Daniel K. McDonald DDS Robert W. Joyner MD 《Journal of oral and maxillofacial surgery》1988,46(12):1048-1050
In a double-blind, randomized plan of drug administration, nalbuphine, fentanyl, and a placebo were compared for efficacy in sedation and analgesia during third molar removal. Fifty-eight patients participated in this study. Using accepted intravenous sedation and surgical techniques, fentanyl and nalbuphine were found to be better than placebo for anxiety and pain control in third molar surgery. Fentanyl had a longer duration of pain relief postoperatively than did nalbuphine. The study confirmed the need for a narcotic supplement to sedation techniques for third molar surgery. 相似文献
945.
Outcomes of 829 neonates with complete transposition of the great arteries 12-17 years after repair. 总被引:6,自引:0,他引:6
William G Williams Brian W McCrindle David A Ashburn Richard A Jonas Constantine Mavroudis Eugene H Blackstone 《European journal of cardio-thoracic surgery》2003,24(1):1-9; discussion 9-10
OBJECTIVE: Between 1985 and 1989, the surgical management of neonates with complete transposition (TGA) underwent a transition from atrial to arterial repair. We sought to examine the intermediate outcomes and their associated risk factors in neonates repaired during the era of transition. PATIENTS AND METHODS: Twenty-four institutions entered 829 neonates age less than 15 days in a prospective study. Diagnosis was simple TGA (n=631), TGA with ventricular septal defect (VSD) (n=167), TGA with VSD and pulmonary stenosis (TGA/VSD/PS) (n=30), or TGA with PS (n=1). Repair was by arterial switch (n=516), atrial repair (Senning=175, Mustard=110) or Rastelli (n=28). Time-related events were analysed by parametric hazard function modeling and incremental risk factors for mortality, re-intervention, and late functional assessment were sought. RESULTS: Survival estimates at 6 months, 5, 10, and 15 years are 85, 83, 83, and 81%, respectively. The hazard function for death after repair has two phases: an early rapidly declining phase and an ongoing constant one. Constant phase mortality is less likely after the arterial switch operation and in children with simple TGA. During follow up, at least one re-intervention was required in 167 children (pacemaker, n=35; percutaneous intervention, n=32; baffle re-intervention, n=27; re-operation, n=125). Freedom from re-intervention at 6 months, 5, 10 and 15 years is 93, 82, 77, and 76%, respectively. Of survivors, 87% have been followed up to the last 3 years, including an assessment of functional ability of 562 children (83%). Functional class 15 years after repair is class I in 76%, II in 22%, III in 2%. The proportion in functional class I decreased over time. Psychosocial deficits, especially learning disorders are prevalent. CONCLUSIONS: Survival 15 years after TGA repair is good with most children functioning well, and results are best after an arterial switch operation. There is an ongoing risk of death that is less after the arterial switch operation. With the exception of Rastelli patients, the likelihood of survivors needing re-intervention after 5 years is low. There is need for improved neurodevelopmental outcomes. 相似文献
946.
David A Warrell 《British medical journal》2005,331(7527):1244-1247
947.
948.
David G Biron Cécile Joly Laurent Marché Nathalie Galéotti Vincent Calcagno Andreas Schmidt-Rhaesa Lionnel Renault Frédéric Thomas 《Infection, genetics and evolution》2005,5(2):167-175
The proteome of most parasite species is currently unknown. Hairworms (Nematomorpha), 300 species distributed around the world, are parasitic in arthropods (mainly terrestrial species) when juveniles, but they are free-living in aquatic environments when adult. Most aspects of their systematics and biology are currently unknown. The aim of this paper was (i) to report a novel and reproducible protocol for the analysis of the proteome of hairworms using two-dimensional gel electrophoresis (2-DGE) and mass spectrometry (matrix laser desorption ionization-time of flight mass spectrometry (MALDI-TOF)) and (ii) to determine the level of proteomic divergence between two sympatric but taxonomically unrelated nematomorph species in the adult stage, Paragordius tricuspidatus Dufour (Nematomorpha, Gordiidae) and Spinochordodes tellinii Camerano (Nematomorpha, Gordiidae). In total, 689 protein spots were observed for P. tricuspidatus, 575 for S. tellinii. Only 36.2% spots were shared between the two species. Quantitative analysis of the proteins which are common to both parasite species reveals substantial differences in the pattern of protein expression. These results suggest a rapid evolutionary divergence between these two nematomorph families. Also, to test the value of our MALDI-TOF protocol, we used Actin-2 (Act-2), a protein highly conserved in the course of evolution. Peptide mass fingerprint (PMF) data obtained for Act-2 of P. tricuspidatus and S. tellinii suggest a very high homology with Act-2 of different worms species belonging to the Bilateria phylum (Annelida and Nematoda) and more specifically to Lumbricus terrestris (Annelida, Lumbricidae) and Caenorhabditis elegans (Nematoda, Rhabditidae). We discuss our results in relationship with current ideas concerning the use of proteomics in systematics. 相似文献
949.
950.
Michael H Duong Todd A MacKenzie David J Malenka 《Catheterization and cardiovascular interventions》2005,64(4):471-479
The objectives of this study was to assess the overall effect of N-acetylcysteine (NAC) in preventing radiocontrast-induced nephropathy (RCIN) using all available data in the literature. RCIN is associated with increased morbidity and mortality. Existing randomized trials of NAC are small and show inconsistent results. Prior meta-analyses do not include data from the most current studies. We used standard search protocols to identify all published articles and abstracts of prospective trials using NAC with fluid hydration compared to hydration alone in patients with chronic renal insufficiency undergoing contrast procedures. A rise in serum creatinine by 0.5 mg/dl or 25% above baseline at 48-72 hr after contrast exposure was used as the primary outcome. We identified 14 trials of NAC with 1,584 patients published as full-text articles. Using a random-effects model, the use of oral NAC resulted in a significant reduction in the risk for developing RCIN (RR = 0.57; 95% CI = 0.37-0.84; P = 0.01). This finding did not significantly change in a fixed-effect model (RR = 0.55; 95% CI = 0.42-0.73) or when the data were reanalyzed using only randomized trials in all forms (i.e., articles and abstracts; RR = 0.67; 95% CI = 0.47-0.95). We identified only one important difference between the positive and the negative studies: the cumulative exposure to contrast media (174 vs. 152 ml). Metaregression did not show a significant relationship between contrast volume and the RR of developing RCIN (P > 0.10). In the trials showing benefit for NAC, the treated patients' postprocedure creatinine unexpectedly decreased by 0.21 mg/dl (95% CI = 0.33-0.08). Prophylaxis with NAC significantly reduces the risk for RCIN. The reasons for improvement in serum creatinine in patients treated with NAC are unclear, but may include improved renal blood flow due to NAC and/or vigorous hydration. 相似文献