首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3236篇
  免费   165篇
  国内免费   32篇
耳鼻咽喉   18篇
儿科学   115篇
妇产科学   79篇
基础医学   517篇
口腔科学   37篇
临床医学   252篇
内科学   904篇
皮肤病学   41篇
神经病学   403篇
特种医学   84篇
外科学   227篇
综合类   9篇
预防医学   165篇
眼科学   35篇
药学   218篇
中国医学   10篇
肿瘤学   319篇
  2024年   10篇
  2023年   29篇
  2022年   62篇
  2021年   104篇
  2020年   58篇
  2019年   60篇
  2018年   108篇
  2017年   80篇
  2016年   72篇
  2015年   101篇
  2014年   118篇
  2013年   175篇
  2012年   259篇
  2011年   242篇
  2010年   135篇
  2009年   145篇
  2008年   241篇
  2007年   226篇
  2006年   218篇
  2005年   194篇
  2004年   207篇
  2003年   156篇
  2002年   146篇
  2001年   30篇
  2000年   25篇
  1999年   38篇
  1998年   34篇
  1997年   28篇
  1996年   21篇
  1995年   10篇
  1994年   20篇
  1993年   18篇
  1992年   8篇
  1991年   4篇
  1990年   5篇
  1989年   4篇
  1988年   5篇
  1987年   4篇
  1986年   7篇
  1984年   4篇
  1983年   4篇
  1980年   1篇
  1978年   2篇
  1977年   2篇
  1974年   1篇
  1972年   1篇
  1971年   2篇
  1969年   2篇
  1967年   2篇
  1966年   3篇
排序方式: 共有3433条查询结果,搜索用时 15 毫秒
21.
22.
An exceptional case of tracheal agenesis with no communication with the esophagus is described. This malformation needs surgical airway approach and is hardly classifiable. We analyzed the literature and our institutional data: this resulted to be the first case of such anatomical variant. Genetic and pathological issues are reviewed: recent genetic data seem to explain this malformation. We also reviewed the available literature about prenatal presentation. Because prenatal diagnosis is difficult to achieve and current guidelines for neonatal resuscitation do not provide any recommendation, the resuscitative team may not be prepared for managing such a case. Usefulness of uncommon resuscitative maneuvers is discussed: a promptly performed surgical tracheotomy is the only mean to ventilate such a baby.  相似文献   
23.

Background

Phosphodiesterase 5 inhibitors (PDE5-Is) are a mainstay in the therapy of erectile dysfunction (ED). The primary end point of clinical efficacy, both in clinical studies and normal practice, is represented by the International Index of Erectile Function (IIEF).

Objective

To evaluate if platelet cyclic guanosine monophosphate (cGMP) could represent a valuable marker for PDE5-I activity in ED.

Design, setting, and participants

The study enrolled 46 patients with psychogenic, organic, and mixed ED (20–71 yr of age; IIEF score <26). Patients were randomized to 6 wk of vardenafil, 5 mg/d at bedtime, or placebo.

Intervention

All patients donated two blood samples, one before starting the protocol and the second after 6 wk of treatment.

Measurements

Platelet cGMP was measured in both placebo and vardenafil groups. All the patients completed the IIEF-Erectile Function (EF) domain and the sexual encounter profile (SEP) and underwent visual sexual stimulation (VSS) coupled with Rigiscan. All the measurements were performed prior to starting the protocol and after the 6 wk of treatment.

Results and limitations

Platelet cGMP production was significantly (p < 0.05) elevated in patients taking 5 mg vardenafil versus placebo. Vardenafil was not superior to placebo in improving IIEF-EF and SEP scores. Conversely, VSS-Rigiscan revealed a significant amelioration (p < 0.028) in the vardenafil group versus placebo. The changes in platelet cGMP level correlated well with VSS-Rigiscan (p = 0.0037) but not with IIEF-EF and SEP.

Conclusions

Platelet cGMP could represent a relatively simple, reliable, and objective biomarker of PDE5-I activity in ED clinical studies. Larger clinical studies are needed to further validate the use, utility, and limits of this assay.  相似文献   
24.
Background  The complexity of pain from laparoscopic cholecystectomy and the need for treating incident pain provide rationale for multipharmacological analgesia. We investigated the preoperative administration of controlled-release (CR) oxycodone as transition opioid from remifentanil infusion for pain after laparoscopic cholecystectomy. Methods  Fifty consecutive patients undergoing laparoscopic cholecystectomy were randomly, double-blindly assigned to treatment group (n = 25, CR oxycodone: 1 h before surgery and 12 h after the first administration) or to the control group (n = 25, placebo: administered at the same intervals). General anaesthesia was maintained with propofol and remifentanil target-controlled infusions (TCIs). All patients received ketorolac 30 mg i.v. Tramadol i.v. was administered for patient-controlled analgesia (PCA) postoperatively. Numerical rating scale for pain at rest and at movement (NRSr and NRSi), tramadol consumption, times to readiness to surgery and awakening, times to modified Aldrete’s and modified Post-Anesthetic Discharge Scoring System (PADSS) >9 and side effects were evaluated. Results  All NRSr and NRSi and tramadol consumption were significantly lower in the treatment group. The oxycodone group showed higher modified Aldrete’s scores at each time and reached a PADSS >9 faster. Side effects and postoperative nausea and vomiting episodes were comparable. Conclusions  We demonstrated the success of a multipharmacological treatment including opioid premedication with CR oxycodone used as transition opioid for TCI remifentanil infusion; the treatment group showed lower pain scores and rescue analgesic consumption, shorter time to discharge from recovery room and from surgical ward, and the same incidence of side effects, comparably to controls. Sources of financial support for the work: University of Parma, viale Gramsci 14, 43100 Parma PR, Italy.  相似文献   
25.
OBJECTIVES: To describe our experience concerning sudden sensorineural hearing loss (SSNHL) in a large single-institution series of SSNHL patients and to discuss the results. METHOD: This was a retrospective study, and the charts of 156 consecutive inpatients (65 males, mean age 44 years, range 10-74 years; 91 females, mean age 46 years, range 15-75 years) with the diagnosis of SSNHL from 1987 to 2000 were reviewed. One hundred forty-three of 156 patients received multidrug therapy (plasma expanders, antiaggregants, steroids), whereas only 13 SSNHL patients received hyperbaric oxygen therapy. RESULTS: Old age, vascular and metabolic risk factors, and cigarette smoking do not a have a high prevalence in the SSNHL population. An etiologic factor was detected in 23 of 156 (15%) cases (16 cases of acute infection, 4 cases of neurovascular conflicts, 2 cases of cerebellar angiomas, 1 case of cochleovestibular schwannoma). The outcome was not related to the laterality, age, or hearing loss type. On the contrary, a statistically significant association between poor recovery and male sex, both tinnitus and vertigo, and the initial severity of the hearing loss was observed. CONCLUSIONS: Mostly, SSNHL results in idiopathic disease. At present, diagnostic and therapeutic efforts appear to be inadequate to improve the prognosis of SSNHL. Further studies are needed to obtain better knowledge about the etiopathogenesis of SSNHL so that new therapeutic strategies can be considered in the treatment of this challenging ear disease.  相似文献   
26.
PURPOSE: To review systematically the sensitivity and specificity of optical coherence tomography (OCT) for diagnosing macular edema attributable to diabetic retinopathy compared with well-established gold standard tests such as fundus stereophotography or contact and noncontact fundus biomicroscopy. METHODS: Medline and Embase were searched electronically and six major ophthalmic journals from 1998 to 2006 were hand searched. Two reviewers independently assessed trial searches, studied quality with the QUADAS (Quality Assessment of Diagnostic Accuracy Studies) checklist, and extracted data. The target disease was clinically significant macular edema (CSME) according to Early Treatment of Diabetic Retinopathy Study (ETDRS) criteria. A bivariate model was used to obtain summary estimates of sensitivity and specificity and fit a summary receiver operating characteristic (ROC) curve. RESULTS: Fifteen studies were considered eligible. These studies were of good quality for most items of the QUADAS checklist, but most studies did not report masking of examiners and did not describe how withdrawals and undetermined results were treated. Seven studies included healthy control subjects, which could have artificially enhanced OCT diagnostic performance. All but one study included both eyes of the patients without taking into account the within-subject correlation in statistical analyses. Sensitivity and specificity data could be extracted from only 6 of 15 studies, because appropriate cross tabulations of index and reference tests were not reported by the others. In five of these studies, central retinal thickness cutoffs between 230 and 300 microm were adopted to define abnormal OCT results and considered the central type of CSME only, whereas in one study a complex algorithm accounting for extrafoveal CSME was used. The design of one study was case-control and was excluded from the meta-analysis. The expected operating point on the summary ROC, a pooled estimate of all studies, corresponded to a sensitivity of 0.79 (95% CI: 0.71-0.86), a specificity of 0.88 (95% CI: 0.80-0.93), a positive likelihood ratio of 6.5 (95% CI: 4.0-10.7), and a negative likelihood ratio of 0.24 (95% CI: 0.17-0.32). These values suggest a good overall performance of OCT for diagnosing CSME. CONCLUSIONS: OCT performs well compared with fundus stereophotography or biomicroscopy to diagnose diabetic macular edema. The quality of reporting of such studies should be improved, and authors should present cross tabulations of index and reference test results. Data adjusted for within-subject correlation should also be provided, although this issue represents a challenge for systematic reviewers.  相似文献   
27.
    
The choice of an antiretroviral regimen can often impact on adherence, treatment satisfaction and therefore influence on clinical outcome. These concerns are particularly true in adolescents. In this setting, adherence is usually affected by multifactor events and biopsychosocial factors, which connect and changeover time. We evaluated the effect of a switch to a single-pill fixed-dose regimen on patient-reported outcomes, virologic and immunologic outcomes, and safety in a cohort of adolescents with perinatal HIV-1 infection. In addition, we evaluated the effect on low-level residual HIV-RNA. An open-label, non-randomised study was performed: 12 adolescents with a confirmed viremia <50 copies/mL treated with lamivudine or emtricitabine, tenofovir and efavirenz were switched to one-pill fixed-dose regimen of emtricitabine/tenofovir/efavirenz. At the end of follow-up, the new regimen was associated with improvements in treatment satisfaction, HIV-symptoms, whereas adherence remained high. No immunological or virological significative changes were observed. No side-effects were registered. Moreover, the low-level residual HIV-RNA was <3 copie/mL in all patients. One-pill fixed-dose regimen is an added value that favours adherence, reduces HIV-symptoms, improves patients' satisfaction and could better control of HIV-RNA in adolescents, too.  相似文献   
28.
In β-thalassemia, the mechanism driving ineffective erythropoiesis (IE) is insufficiently understood. We analyzed mice affected by β-thalassemia and observed, unexpectedly, a relatively small increase in apoptosis of their erythroid cells compared with healthy mice. Therefore, we sought to determine whether IE could also be characterized by limited erythroid cell differentiation. In thalassemic mice, we observed that a greater than normal percentage of erythroid cells was in S-phase, exhibiting an erythroblast-like morphology. Thalassemic cells were associated with expression of cell cycle–promoting genes such as EpoR, Jak2, Cyclin-A, Cdk2, and Ki-67 and the antiapoptotic protein Bcl-XL. The cells also differentiated less than normal erythroid ones in vitro. To investigate whether Jak2 could be responsible for the limited cell differentiation, we administered a Jak2 inhibitor, TG101209, to healthy and thalassemic mice. Exposure to TG101209 dramatically decreased the spleen size but also affected anemia. Although our data do not exclude a role for apoptosis in IE, we propose that expansion of the erythroid pool followed by limited cell differentiation exacerbates IE in thalassemia. In addition, these results suggest that use of Jak2 inhibitors has the potential to profoundly change the management of this disorder.  相似文献   
29.

Purpose

Granular cell tumors of the neurohypophysis are rare, solitary lesions, mostly presenting in the adult age. They rarely grow to a sufficient size to cause mass effect related symptoms and they may be found in most cases incidentally at autopsy. Because of their rarity as of now they have been described only as case reports or included in small clinical series.

Methods

We report a series of 11 patients, who underwent surgery for granular cell tumors of the neurohypophysis between 1996 and 2013 in a single center.

Results

Mean follow-up time after treatment was 92.2 months (range 9–231 months). Mean age at surgery was 40.7 years (range 12–66 years). There were 7 males (63.6 %) and 4 females (36.4 %). Main symptoms at presentation were: hyperprolactinemia (72.7 %), visual impairment (45.5 %) and headache (36 %). Except for 2 patients, all the others underwent surgery as primary treatment at our Institution, through a transsphenoidal (54.5 %) or a transcranial approach (45.5 %). Overall- and progression-free survival times for the entire series (calculated from the time of diagnosis) were 112.9 and 100.5 months respectively. There was one case of perioperative death in a patient who had undergone repeat transcranial surgery for residual tumor.

Conclusions

Although extremely rare, granular cell tumors of the neurohypophysis have to be considered in the differential diagnosis of suprasellar masses, to avoid misleading interpretation and consequent wrong therapeutic management. Early diagnosis, extensive tumor removal, opportune indication of adjuvant radiotherapy are the keys to manage these cases.
  相似文献   
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号