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   2420篇
  免费   131篇
  国内免费   19篇
耳鼻咽喉   27篇
儿科学   81篇
妇产科学   98篇
基础医学   254篇
口腔科学   47篇
临床医学   186篇
内科学   541篇
皮肤病学   31篇
神经病学   79篇
特种医学   134篇
外国民族医学   1篇
外科学   528篇
综合类   49篇
预防医学   111篇
眼科学   69篇
药学   164篇
中国医学   7篇
肿瘤学   163篇
  2023年   20篇
  2022年   55篇
  2021年   76篇
  2020年   69篇
  2019年   92篇
  2018年   141篇
  2017年   92篇
  2016年   60篇
  2015年   74篇
  2014年   113篇
  2013年   116篇
  2012年   173篇
  2011年   169篇
  2010年   110篇
  2009年   95篇
  2008年   123篇
  2007年   135篇
  2006年   132篇
  2005年   128篇
  2004年   101篇
  2003年   86篇
  2002年   83篇
  2001年   32篇
  2000年   22篇
  1999年   20篇
  1998年   13篇
  1997年   6篇
  1996年   13篇
  1995年   13篇
  1994年   8篇
  1993年   13篇
  1992年   16篇
  1991年   15篇
  1990年   17篇
  1989年   20篇
  1988年   12篇
  1987年   16篇
  1986年   8篇
  1985年   4篇
  1984年   4篇
  1983年   6篇
  1981年   5篇
  1980年   7篇
  1978年   4篇
  1976年   6篇
  1975年   5篇
  1974年   7篇
  1972年   5篇
  1969年   3篇
  1965年   6篇
排序方式: 共有2570条查询结果,搜索用时 139 毫秒
41.
Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer and remains the deadliest form of cancer in the United States and worldwide. New therapies are highly sought after to improve outcome. The effect of sodium-R-alpha lipoate on camptothecin- and paclitaxel-induced cytotoxicity was evaluated on A549 NSCLC and BEAS-2B “normal” lung epithelial cells. Combination indices (CI) and dose reduction indices (DRI) were investigated by studying the cytotoxicity of sodium-R-alpha lipoate (0–16 mM), camptothecin (0–25 nM) and paclitaxel (0–0.06 nM) alone and in combination. 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium-bromide (MTT) was used to assess cytotoxicity. The combinational cytotoxic effects of sodium-R-alpha lipoate with camptothecin or paclitaxel were analyzed using a simulation of dose effects (CompuSyn® 3.01). The effects of sodium-R-alpha lipoate on camptothecin- and paclitaxel-induced cytotoxicity varied based on concentrations and treatment times. It was found that sodium-R-alpha lipoate wasn't cytotoxic toward BEAS-2B cells at any of the concentrations tested. For A549 cells, CIs [(additive (CI = 1); synergistic (CI < 1); antagonistic (CI < 1)] were lower and DRIs were higher for the camptothecin/sodium-R-alpha-lipoate combination (CI = ~0.17–1.5; DRI = ~2.2–22.6) than the paclitaxel/sodium-R-alpha-lipoate combination (CI = ~0.8–9.9; DRI = ~0.10–5.8) suggesting that the camptothecin regimen was synergistic and that the addition of sodium-R-alpha lipoate was important for reducing the camptothecin dose and potential for adverse effects.  相似文献   
42.

Background

Hydroxyurea reduces complications and improves health-related quality of life (HRQOL) in sickle cell disease (SCD) patients, however adherence remains suboptimal. Understanding patients’ views of hydroxyurea is critical to optimize adherence, particularly in adolescents and young adults (AYA). Study objectives were to assess beliefs about hydroxyurea using the Beliefs about Medicines Questionnaire (BMQ), and to examine the relationship of patients’ beliefs to their hydroxyurea adherence and HRQOL.

Methods

Thirty-four AYA with SCD participated in a cross-sectional study January–December 2015. Study assessments included BMQ to examine beliefs about hydroxyurea; Visual Analogue Scale (VAS) to assess hydroxyurea adherence; and Patient Reported Outcomes Measurement Information System (PROMIS®) to evaluate HRQOL.

Results

Participants (41% female, 91% Black) had median age of 13.5 (IQR 12–18) years. Participants’ concerns about overuse of medications correlated with concerns about hydroxyurea (rs?=?0.36, p?=?0.04) and overall harm of medications (rs?=?0.5, p?=?0.003). Participants’ age positively correlated with the necessity of hydroxyurea (rs?=?0.45, p?=?0.007). Participants’ concerns about hydroxyurea and overuse of medications positively correlated with anxiety (rs?=?0.41, p?=?0.02; rs?=?0.44, p?=?0.01) and depression (rs?=?0.37, p?=?0.04; rs?=?0.54, p?=?0.001), but inversely correlated with peer relationships (rs?=??0.45, p?=?0.03; rs?=??0.44, p?=?0.03), respectively, suggesting better HRQOL with concerns. Fifty percent of participants reported low hydroxyurea adherence (VAS?<?80%), which was more seen in patients with higher concerns about hydroxyurea (p?=?0.02).

Conclusions

Beliefs about hydroxyurea correlated with HRQOL scores and adherence levels. Addressing patients’ concern about hydroxyurea and medications overall as well as routine assessment of adherence and beliefs could help to overcome adherence barriers.  相似文献   
43.
We measured serum interleukin-2 receptor (sIL-2R), tumor necrosis factor-a (TNF-a), Fas receptor (sFas), nitric oxide (NO), and angiotensin converting enzyme (ACE) activity in 45 patients with congestive heart failure (CHF) of different etiologies. The relatioship between these bioindices and the severity of heart failure was analysed. Patients were classified according to the etiology of heart failure into: 15 patients with rheumatic valvular heart disease (RHD), 17 with ischemic heart disease (IHD) and 13 with idiopathic dilated cardiomyopathy (DCM). Patients were further classified according to severity of CHF following the New York Heart Association classification (NYHA) into: NYHA class II (n= 7), NYHA class III (n=20) and NYHA class IV (n=18). Eighteen healthy subjects were included as controls. Serum sIL-2R, TNF-alpha and sFas levels were determined by ELISA while serum NO and ACE levels were measured by colorimetric methods. Doppler Echocardiography was performed for all participants. Levels of sIL-2R, TNF-alpha, sFas, NO, and ACE were significantly higher in CHF patients than controls. Levels of the bioindices varied according to the CHF etiology. TNF-a level was the only one that had significant differences among different subgroups (RHD, IHD and DCM). The levels of sIL-2R, TNF-alpha, NO and sFas in patients with NYHA class IV were significantly higher than class II or III. Moreover, sIL-2R, TNF-alpha and NO levels were significantly higher in patients with diastolic dysfunction than patients with normal diastolic function. A significant positive correlations were found between sFas and both TNF-alpha and sIL-2R and between TNF-alpha and both NO and diastolic function. In addition, significant positive correlations were found between TNF-alpha and sIL-2R in both IHD and RHD patients and between sIL-2R and both ACE in IHD patients and diastolic function in DCM patients. It is concluded that a relationship exists between immune system activation, apoptosis and renin- angiotensin system in CHF and this may play a significant role in the pathophysiology and prognosis of the disease.  相似文献   
44.
Nineteen patients with Fanconi anemia (FA) and bone marrow failure underwent bone marrow transplantation (BMT) from matched siblings. Median age at BMT was 8.7 years. Conditioning consisted of low-dose cyclophosphamide (CY 5 mg/kg x 4 days) and thoracoabdominal irradiation (TAI 400 cGy). Graft-versus-host disease (GVHD) prophylaxis was cyclosporin A (CsA) in 13 patients and CsA plus methotrexate in 6 patients. Antithymocyte globulin (ATG) was added in the pretransplant as well as the post-transplant period. All patients received high-dose acyclovir from day 2 pre-BMT to day 28 post BMT, and intravenous immunoglobulins (IVIG), 500 mg/kg weekly from day 7 pre-BMT to day 90 post BMT. No fungal prophylaxis was given. All patients engrafted, (median, 14 days for an absolute neutrophil count > or =0.5 x 10(9)/l; median, 37 days for platelet count > or =20 x 10(9)/l). Fourteen (74%) patients are alive with sustained engraftment and are transfusion independent. Three (16.6%) patients developed acute GVHD; none developed chronic GVHD. Five (26%) patients developed invasive fungal infections, and two (10%) developed fatal CMV disease. We believe the addition of ATG may have contributed to the increased incidence of severe life-threatening fungal and viral infections in our series.  相似文献   
45.
OBJECTIVES: Eosinophilic esophagitis, previously confused with esophageal inflammation due to gastroesophageal reflux, has recently begun to be distinguished from it. We undertook this analysis of our large series of children with the condition to clarify its spectrum: its presenting symptoms; its relation to allergy, respiratory disease, and reflux; its endoscopic and histological findings; and its diagnosis and therapy. METHODS: We analyzed the details of our clinical series of 30 children with eosinophilic esophagitis, defining it as > or =5 eosinophils per high power field in the distal esophageal epithelium. Retrospective chart review was supplemented by prospective, blinded, duplicate quantitative evaluation of histology specimens, and by telephone contact with some families to clarify subsequent course. Presentation and analysis of the series as a whole is preceded by a case illustrating a typical presentation with dysphagia and recurrent esophageal food impactions. RESULTS: Presenting symptoms encompass vomiting, pain, and dysphagia (some with impactions or strictures). Allergy, particularly food allergy, is an associated finding in most patients, and many have concomitant asthma or other chronic respiratory disease. A subtle granularity with furrows or rings is newly identified as the endoscopic herald of histological eosinophilic esophagitis. Histological characteristics include peripapillary or juxtaluminal eosinophil clustering in certain cases. Association with eosinophilic gastroenteritis occurs, but is not common. Differentiation from gastroesophageal reflux disease is approached by analyzing eosinophil density and response to therapeutic trials. Therapy encompasses dietary elimination and anti-inflammatory pharmacotherapy. CONCLUSION: Awareness of the spectrum of eosinophilic esophagitis should promote optimal diagnosis and treatment of this elusive entity, both in children and in adults.  相似文献   
46.
47.
48.
49.
Purpose

The purpose of the study was to determine if the ≥ 15 mm threshold currently used to define PIRADS 5 lesions is the optimal size threshold for predicting high likelihood of clinically significant (CS) cancers.

Materials

Three hundred and fifty-eight lesions that may be changed from category 4 to 5 or vice versa on the basis of the size criterion (category 4: n = 288, category 5: n = 70) from 255 patients were evaluated. Kendall’s tau-b statistic accounting for inter-lesion correlation, generalized estimation equation logistic regression, and receiver operating curve analysis evaluated two lesion size-metrics (lesion diameter and relative lesion diameter—defined as lesion diameter/prostate volume) for ability to identify CS (Gleason grade ≥ 3 + 4) cancer at targeted biopsy. Optimal cut-points were identified using the Youden index. Analyses were performed for the whole prostate (WP) and zone-specific sub-cohorts of lesions in the peripheral and transition zones (PZ and TZ).

Results

Lesion diameter showed a modest correlation with Gleason grade (WP: τB = 0.21, p < 0.0001; PZ: τB = 0.13, p = 0.02; TZ: τB = 0.32, p = 0.001), and association with CS cancer detection (WP: AUC = 0.63, PZ: AUC = 0.59, TZ: AUC = 0.74). Empirically derived thresholds (WP: 14 mm, PZ: 13 mm, TZ: 16 mm) performed similarly to the current ≥ 15 mm standard. Lesion relative lesion diameter improved identification of CS cancers compared to lesion diameter alone (WP: τB = 0.30, PZ: τB = 0.24, TZ: τB = 0.42, all p < 0.0001). AUC also improved for WP and PZ lesions (WP: AUC = 0.70, PZ: AUC = 0.68, and TZ: AUC = 0.74).

Conclusions

The current ≥ 15 mm diameter threshold is a reasonable delineator of PI-RADS category 4 and category 5 lesions in the absence of extraprostatic extension to predict CS cancers. Additionally, relative lesion diameter can improve identification of CS cancers and may serve as another option for distinguishing category 4 and 5 lesions.

  相似文献   
50.

Purpose

“Endometriosis” is defined such as the presence of endometrial glands and stroma outside the uterine cavity. This ectopic condition may develop as deeply infiltrating endometriosis (DIE) when a solid mass is located deeper than 5 mm underneath the peritoneum including the intestinal wall. The ideal surgical treatment is still under search, and treatment may range from simple shaving to rectal resection. The aim of the present systematic review is to report and analyze the postoperative outcomes after rectosigmoid resection for endometriosis.

Methods

We performed a systematic review according to Meta-analysis of Observational Studies in Epidemiology guidelines. The search was carried out in the PubMed database, using the keywords: “rectal resection” AND “endometriosis” and “rectosigmoid resection” AND “endometriosis.” The search revealed 380 papers of which 78 were fully analyzed.

Results

Thirty-eight articles published between 1998 and 2017 were included. Three thousand seventy-nine patients (mean age 34.28?±?2.46) were included. Laparoscopic approach was the most employed (90.3%) followed by the open one (7.9%) and the robotic one (1.7%). Overall operative time was 238.47?±?66.82. Conversion rate was 2.7%. In more than 80% of cases, associated procedures were performed. Intraoperative complications were observed in 1% of cases. The overall postoperative complications rate was 18.5% (571 patients), and the most frequent complication was recto-vaginal fistula (74 patients, 2.4%). Postoperative mortality rate was 0.03% and mean hospital stay was 8.88?±?3.71 days.

Conclusions

Despite the large and extremely various number of associated procedures, rectosigmoid resection is a feasible and safe technique to treat endometriosis.
  相似文献   
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