全文获取类型
收费全文 | 12526篇 |
免费 | 798篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 93篇 |
儿科学 | 369篇 |
妇产科学 | 274篇 |
基础医学 | 1421篇 |
口腔科学 | 196篇 |
临床医学 | 1105篇 |
内科学 | 2926篇 |
皮肤病学 | 200篇 |
神经病学 | 1210篇 |
特种医学 | 454篇 |
外科学 | 1558篇 |
综合类 | 222篇 |
一般理论 | 5篇 |
预防医学 | 1440篇 |
眼科学 | 218篇 |
药学 | 909篇 |
中国医学 | 56篇 |
肿瘤学 | 705篇 |
出版年
2024年 | 17篇 |
2023年 | 71篇 |
2022年 | 72篇 |
2021年 | 250篇 |
2020年 | 140篇 |
2019年 | 249篇 |
2018年 | 414篇 |
2017年 | 295篇 |
2016年 | 258篇 |
2015年 | 295篇 |
2014年 | 366篇 |
2013年 | 538篇 |
2012年 | 792篇 |
2011年 | 911篇 |
2010年 | 521篇 |
2009年 | 421篇 |
2008年 | 799篇 |
2007年 | 891篇 |
2006年 | 816篇 |
2005年 | 833篇 |
2004年 | 804篇 |
2003年 | 799篇 |
2002年 | 732篇 |
2001年 | 283篇 |
2000年 | 359篇 |
1999年 | 259篇 |
1998年 | 104篇 |
1997年 | 63篇 |
1996年 | 53篇 |
1995年 | 55篇 |
1994年 | 63篇 |
1993年 | 45篇 |
1992年 | 98篇 |
1991年 | 80篇 |
1990年 | 63篇 |
1989年 | 69篇 |
1988年 | 46篇 |
1987年 | 41篇 |
1986年 | 44篇 |
1985年 | 35篇 |
1984年 | 20篇 |
1982年 | 22篇 |
1981年 | 27篇 |
1979年 | 26篇 |
1978年 | 28篇 |
1977年 | 25篇 |
1976年 | 26篇 |
1975年 | 14篇 |
1974年 | 16篇 |
1972年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
Torabinejad M Anderson P Bader J Brown LJ Chen LH Goodacre CJ Kattadiyil MT Kutsenko D Lozada J Patel R Petersen F Puterman I White SN 《The Journal of prosthetic dentistry》2007,98(4):285-311
STATEMENT OF PROBLEM: Dentists and patients are regularly confronted by a difficult treatment question: should a tooth be saved through root canal treatment and restoration (RCT), be extracted without any tooth replacement, be replaced with a fixed partial denture (FPD) or an implant-supported single crown (ISC)? PURPOSE: The purpose of this systematic review was to compare the outcomes, benefits, and harms of endodontic care and restoration compared to extraction and placement of ISCs, FPDs, or extraction without tooth replacement. MATERIAL AND METHODS: Searches performed in MEDLINE, Cochrane, and EMBASE databases were enriched by hand searches, citation mining, and expert recommendation. Evidence tables were developed following quality and inclusion criteria assessment. Pooled and weighted mean success and survival rates, with associated confidence intervals, were calculated for single implant crowns, fixed partial dentures, and initial nonsurgical root canal treatments. Data related to extraction without tooth replacement and psychosocial outcomes were evaluated by a narrative review due to literature limitations. RESULTS: The 143 selected studies varied considerably in design, success definition, assessment methods, operator type, and sample size. Direct comparison of treatment types was extremely rare. Limited psychosocial data revealed the traumatic effect of loss of visible teeth. Economic data were largely absent. Success rates for ISCs were higher than for RCTs and FPDs, respectively; however, success criteria differed greatly among treatment types, rendering direct comparison of success rates futile. Long-term survival rates for ISCs and RCTs were similar and superior to those for FPDs. CONCLUSIONS: Lack of comparative studies with similar outcomes criteria with comparable time intervals limited comparison of these treatments. ISC and RCT treatments resulted in superior long-term survival, compared to FPDs. Limited data suggested that extraction without replacement resulted in inferior psychosocial outcomes compared to alternatives. Long-term, prospective clinical trials with large sample sizes and clearly defined outcomes criteria are needed. 相似文献
13.
14.
Conversion from cyclosporin A to tacrolimus as a non-surgical alternative to reduce gingival enlargement: a preliminary case series 总被引:4,自引:0,他引:4
Hernández G Arriba L Frías MC de la Macorra JC de Vicente JC Jiménez C de Andrés A Moreno E 《Journal of periodontology》2003,74(12):1816-1823
BACKGROUND: Gingival enlargement (GE) is a frequent side effect that occurs in organ transplant recipients (OTR) after the administration of cyclosporin A (CsA). The availability of new drugs used to suppress graft rejection in OTR offers an opportunity to manage GE non-surgically. This preliminary case series aimed to analyze the effect of CsA withdrawal and its substitution by another immunosuppressant in OTR with severe GE. METHODS: Four organ transplant recipients who had received a liver or renal allograft were recruited for this study. All OTR had developed clinically severe CsA-induced GE. GE scores were assessed for each patient at baseline and at weeks 2, 4, 8, 12, 16, and 54 following conversion to tacrolimus. Scaling and root planing were initially performed and repeated monthly during the first 6 months. Careful polishing of the teeth was carried out once every 2 weeks until month 6 and then monthly until month 12. Hygiene instructions and reinforcement to optimize oral hygiene were maintained throughout the study. RESULTS: The four patients showed a rapid decrease in their gingival symptoms and in the size of the gingivae. This change was clinically evident 8 weeks after conversion to tacrolimus. One year later, all the patients experienced GE regression, although some anatomic irregularities persisted in the interdental papillae of one of the patients. No adverse effects from tacrolimus were observed during the study except in one patient who presented headaches. CONCLUSION: It seems that CsA withdrawal and its conversion to tacrolimus in organ transplant recipients who develop severe gingival enlargement, together with an extensive plaque control program, provide an effective means to control/eliminate gingival hyperplasia, with minimal risk of graft dysfunction. 相似文献
15.
I D Jiménez 《American journal of orthodontics and dentofacial orthopedics》1989,95(4):282-288
The purpose of this study was to investigate whether anteroposterior changes in mandibular position affect masticatory muscle activity. The electromyographic (EMG) activity of masticatory muscles during full and partial (10%) clenching in three mandibular bite registration positions--retruded contact position (RCP), intercuspal position (IP), and muscular position (MP)--was studied. Three groups of subjects with different ranges of anteroposterior positioning of the condyles were evaluated (normal occlusion, Class II, Division 2 malocclusion, and dual bite malocclusion). A posterior stabilizing splint for each registration position was made. EMG data were obtained from three bilateral muscles (masseter, anterior temporal, and posterior temporal). Clenching in the RCP elicited the lowest masseter muscle activity during full clenching, and the highest anterior temporal and posterior temporal muscle activity during partial clenching. If the relationships of the masticatory muscles are analyzed through a ratio that represents the interaction between biting and positioning muscles (masseter/posterior temporal muscle ratio), the RCP as compared with other positions had the lowest ratio. The RCP required more positioning muscle activity and permitted less biting muscle activity. There was no significant difference in the muscle activity between the IP and MP registrations. Small changes in jaw position (anterior to RCP) are not critical for the masticatory apparatus provided there is good intercuspation. The results of this investigation suggest that intercuspation in RCP is not the optimal position. 相似文献
16.
Andrea Orosa Andrada José Miguel Gómez De Vicente Miguel Ángel Jiménez Cidre 《International urogynecology journal》2014,25(3):429-431
Acute urinary retention (AUR) in women is an uncommon occurrence described by the International Continence Society (ICS) as a painful, palpable, or perceptible bladder when the patient is unable to pass urine. Contrarily to men, AUR in women is not usually due to any obstructive process. Neurologic causes are the most common reason for AUR in reproductive-age women. A few case reports have been published concerning women suffering from gynecological pathology and AUR, and they propose extrinsic compression of the urinary tract. In the case we report, AUR pathophysiology was compression of the pelvic plexus by a giant uterine leiomyoma. An electromyogram displayed motor polyradiculopathy of S1 and S2 nerve roots, and the patient was unable to urinate due to an uncontractible bladder. 相似文献
17.
Sonographic and Doppler imaging in the diagnosis and treatment of gestational trophoblastic disease: a 12-year experience. 总被引:5,自引:0,他引:5
OBJECTIVE: To evaluate the clinical utility of sonography with Doppler examination in the diagnosis and treatment of gestational trophoblastic disease (GTD). METHODS: A retrospective analysis of 355 cases of GTD seen over a 12-year period in 2 large university referral hospitals in China was performed. Clinical appearances, sonographic findings, Doppler waveforms, and patient outcomes were reviewed. Sonographic and Doppler examinations were performed to diagnose the presence of molar tissue, detect invasive disease, assess disease recurrence, and monitor the efficacy of chemotherapy. Doppler waveforms of 13 patients with normal early pregnancies were also examined for comparison. RESULTS: Of the 355 patients with GTD, 106 had a classic hydatidiform mole (CHM), 33 had a partial hydatidiform mole (PHM), 184 had an invasive hydatidiform mole (IHM), and 32 had choriocarcinoma. Sonography showed abnormal molar tissue confined to the endometrial cavity in all cases of CHM. In cases of IHM and choriocarcinoma, soft tissue invasion and cystic vascular spaces within the myometrium were shown. Cases of PHM had a thickened, hydropic placenta with a concomitant fetus. Doppler waveforms showed resistive indices of 0.55 (SD, 0.06) for CHM, 0.56 (SD, 0.04) for PHM, 0.28 (SD, 0.06) for IHM, 0.25 (SD, 0.05) for choriocarcinoma, and 0.66 (SD, 0.04) for normal pregnancies. The abnormal sonographic and Doppler findings in invasive disease resolved when chemotherapy was successful. CONCLUSIONS: Sonography and Doppler imaging were helpful in diagnosing GTD, in determining whether invasive disease was present, in detecting recurrence of disease, and in following the effectiveness of chemotherapy. 相似文献
18.
Johan Lataster Dina Collip Jenny Ceccarini Dennis Hernaus David Haas Linda Booij Jim van Os Jens Pruessner Koen Van Laere Inez Myin-Germeys 《Schizophrenia bulletin》2014,40(1):66-77
Objective: Patients diagnosed with a psychotic disorder and their first-degree relatives display increased reactivity to stress. Theory predicts that experience of psychosocial stress is associated both with ventromedial prefrontal and mesolimbic dopamine neurotransmission. However, while there is evidence of aberrant striatal dopamine processing in psychotic disorder, the role of the prefrontal cortex remains under-researched. This study aimed at investigating stress-induced in vivo dopamine release in ventromedial prefrontal cortex (vmPFC) of individuals at familial risk for psychosis. Method: Fourteen healthy first-degree relatives of patients with a diagnosis of psychotic disorder and 10 control subjects underwent a single dynamic positron emission tomography (PET) scanning session after intravenous administration of 183.2 (SD = 7.6) MBq [18F]fallypride. Psychosocial stress was initiated at 100min postinjection using a computerized mental arithmetic task with social evaluative threat components. PET data were analyzed using the linearized simplified reference region model. Regression analyses were performed to compare the spatial extent of task-related ligand displacement between control subjects and relatives and to find how it related to self-rated experiences of psychosocial stress and psychosis. Results: First-degree relatives displayed hyporeactive dopamine signaling in the vmPFC in response to stress. Increased levels of subjectively rated stress were associated with increased intensity of psychotic experiences. This effect was particularly pronounced in first-degree relatives. Conclusion: Although previous studies have hypothesized a role for prefrontal dopamine dysfunction in psychosis, this study, to our knowledge, is the first in vivo human imaging study showing attenuated (ie, hyporeactive) dopamine stress neuromodulation in vmPFC of individuals at familial risk for psychosis.Key words: schizophrenia, positron emission tomography, neuromodulation, relatives, mesolimbic, salience 相似文献
19.
20.
Luis Jiménez María José Lorda Cástor Méndez 《Journal of autism and developmental disorders》2014,44(7):1597-1608
Two samples of participants with typical development (TD) and high functioning autism performed an imitation task where the goal was of high or low salience, and where the modeled action complied with or was contrary to the end-state comfort (ESC) effect. Imitation was affected by the ESC effect in both groups, and participants with autism reproduced high salient goals as frequently as did participants with TD, but they reproduced less of the low salient goals. Participants with autism showed a reduced tendency to reproduce those actions which were relatively inefficient to reach the goals. The results are discussed in terms of either a relative imbalance between emulation and mimicry in autism, or a reduced tendency to overimitate. 相似文献