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   11366篇
  免费   775篇
  国内免费   42篇
耳鼻咽喉   77篇
儿科学   298篇
妇产科学   246篇
基础医学   1928篇
口腔科学   96篇
临床医学   1040篇
内科学   2532篇
皮肤病学   186篇
神经病学   1270篇
特种医学   295篇
外科学   1133篇
综合类   50篇
一般理论   1篇
预防医学   887篇
眼科学   215篇
药学   750篇
中国医学   20篇
肿瘤学   1159篇
  2024年   10篇
  2023年   100篇
  2022年   158篇
  2021年   331篇
  2020年   213篇
  2019年   308篇
  2018年   401篇
  2017年   246篇
  2016年   245篇
  2015年   313篇
  2014年   447篇
  2013年   571篇
  2012年   978篇
  2011年   967篇
  2010年   514篇
  2009年   543篇
  2008年   831篇
  2007年   853篇
  2006年   748篇
  2005年   753篇
  2004年   666篇
  2003年   651篇
  2002年   624篇
  2001年   61篇
  2000年   53篇
  1999年   63篇
  1998年   94篇
  1997年   94篇
  1996年   69篇
  1995年   51篇
  1994年   46篇
  1993年   39篇
  1992年   21篇
  1991年   15篇
  1990年   11篇
  1989年   8篇
  1988年   10篇
  1987年   7篇
  1986年   9篇
  1985年   3篇
  1984年   4篇
  1983年   4篇
  1982年   5篇
  1981年   3篇
  1979年   4篇
  1978年   4篇
  1968年   3篇
  1966年   3篇
  1964年   3篇
  1942年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Amniotic membrane (AM), the most internal placental membrane, has unique properties including antiadhesive effects, bacteriostatic, wound protection and pain-reduction properties, as well as epithelialization initialization capacities. Furthermore, AM is widely available and less costly than other bioengineered skin substitutes. In a prospective pilot study, we evaluated the safety, feasibility, and the effects on healing of AM graft in 15 patients with chronic venous leg ulcers. AM grafts were prepared from placentas harvested during cesarean section. All grafted AM had adhered to the wound bed 7 days after being applied with a 100% engraftment rate. The percentage of granulation tissue increased significantly (from 17% on day 0 to 69% on day 14, p<0.0001), along with a significant decrease of fibrinous slough (from 36% at day 0 to 16% at day 14, p<0.001). A significant clinical response occurred in 12 patients (80%) including complete healing (20%) in three during the 3-month follow-up period. The ulcer surface area decreased significantly from a mean value (+/- standard deviation) of 4.59 +/- 2.49 cm(2) at baseline to 2.91+/-2.01 cm(2) on day 30 (p<0.001). All patients experienced a significant reduction of ulcer-related pain rapidly after AM transplantation. No adverse events were recorded. AM transplantation seems to function as a safe substrate, promoting proper epithelialization while suppressing excessive fibrosis. Further advantages of biotherapy with AM are its easy and low-cost production, and that it can be applied as an ambulatory treatment without immobilization. AM transplantation may thus be considered to be an alternative method for treating chronic leg ulcers.  相似文献   
102.
Protein deficiency is associated with impaired titanium osseointegration. We studied whether systemic treatment with PTH or pamidronate could influence the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. PTH or pamidronate prevented the deleterious effects of protein undernutrition on bone microarchitecture close to the implant and on mechanical fixation. PTH even significantly improved implant osseointegration. INTRODUCTION: Protein deficiency is highly prevalent among elderly patients hospitalized in orthopedic wards. Reduced protein intake impairs titanium osseointegration in rats. Whether stimulator of bone formation or inhibitor of bone resorption could improve implant osseointegration under protein deprivation is not known. We studied the effects of systemic treatment with PTH or pamidronate on the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. MATERIALS AND METHODS: We measured the resistance to pull-out 1-mm-diameter titanium rods implanted into the proximal tibias of 49 adult female rats receiving a normal or an isocaloric low protein diet. After 2 wk on either diet, the implants were inserted, and the rats received PTH(1-34), pamidronate or saline vehicle for 8 wk. The tibias were removed for microCT morphometry, followed by the evaluation of pull-out strength. RESULTS: Pull-out strength was lower in rats fed an isocaloric low protein diet compared with rats fed a normal protein intake (-29%). PTH and pamidronate significantly increased pull-out strength in animals fed a normal or a low protein diet, the effect of PTH being of higher magnitude. The PTH- or pamidronate-mediated increase in pull-out strength was associated with significant increases of relative bone volume, bone-to-implant contact, and trabecular thickness, whereas trabecular spacing was reduced, in the vicinity of the implants. CONCLUSIONS: We confirmed that isocaloric low protein intake impairs titanium implant osseointegration. PTH or pamidronate prevented the deleterious effects of protein undernutrition and even significantly improved the implant osseointegration. These results indicate that systemic administration of PTH or pamidronate could be considered for preventing uncemented arthroplasty loosening in protein undernourished patients.  相似文献   
103.
BACKGROUND: An imbalance in the ratio of arachidonic acid and docosahexaenoic acid (DHA) was found in cystic fibrosis (CF) affected tissues and was suggested to promote inflammation. Several studies have shown that the long chain n-3 fatty acids reduced inflammatory activity while others have highlighted prooxidant activity of DHA at high concentrations. The aim of our study was to evaluate the effects of an intravenous fish-oil emulsion enriched with n-3 FA in patients with CF on plasma and platelet FA composition and peroxidation markers. METHODS: 13 patients with CF received one IV emulsion per week of 2 mL/kg fish-oil n-3 emulsion for 12 weeks. RESULTS: There was a significant increase in 20:5 n-3 and 22:6 n-3 platelet FA composition, no variation in 20:4 n-6, a decrease in n-9. There was no variation in plasma FA composition. Specific urinary markers of lipid peroxidation derived from n-3 and n-6 showed a very high level before infusion compared with usual values in healthy subjects which was not affected by treatment. A significant weight loss and a decrease in reduced glutathione were observed in adult patients. CONCLUSIONS: The intravenous administration of n-3 FA in CF patients induced a significant modification in platelet FA composition but no modification of oxidative markers. However, the weight loss and the decreased level in reduced glutathione observed in adult patients may suggest a potential deleterious activity for some patients. Further studies are necessary to determine the optimal dose and route for long chain FA administration required to reach a potential beneficial effect.  相似文献   
104.
Sir, We report the occurrence of thrombotic microangiopathy (TMA)that may be directly related to vascular endothelial growthfactor (VEGF) Trap treatment, a fully humanized recombinantfusion protein containing extracellular portions of the extracellulardomains of two different VEGF receptors, VEGFR-1 and VEGFR-2.VEGF Trap is currently under evaluation in combination withLV5FU2-CPT11 in a  相似文献   
105.

Background

We have previously reported on the benefits of Pre-Surgical Exercise Training (PreSET) on physical fitness and social interactions in subjects awaiting bariatric surgery (BS). However, data are needed to know whether these benefits are maintained post-BS.

Objectives

The purpose of this paper was to evaluate the effect of PreSET on physical activity (PA) level, physical fitness, PA barriers, and quality of life (QoL) 1 year (1-Y) after BS.

Methods

Of the 30 participants randomized into two groups (PreSET and usual care), 25 were included in the final analysis. One year after BS, time spent in different PA intensities and number of steps were assessed with an accelerometer. Before BS and until 1-Y after BS, physical fitness was assessed with symptom-limited cardiac exercise test, 6-min walk test (6MWT), and sit-to-stand, half-squat, and arm curl tests. QoL, PA barriers, and PA level were evaluated with questionnaires.

Results

The number of steps (7460 vs 4287) and time spent in light (3.2 vs 2.2 h/day) and moderate (0.6 vs 0.3 h/day) PA were higher in the PreSET group 1-Y after BS. The changes in 6MWT heart cost (1.3 vs 0.6 m/beats/min), half-squat test (38.8 vs 10.3 s), and BMI (? 16.8 vs ? 13.5 kg/m2) were significantly greater in the PreSET group compared to those in the usual care group. No other significant difference between groups was observed.

Conclusion

The addition of the PreSET to individual lifestyle counseling seems effective to improve PA level and submaximal physical fitness 1-Y after BS. Studies with larger cohorts are now required to confirm these results.The trial was registered at clinicaltrials.gov (NCT01452230).
  相似文献   
106.
107.
Implant wear and corrosion have been associated with adverse tissue reactions that can lead to implant failure. Wear and corrosion products are therefore of great clinical concern. For example, Co2+ and Cr3+ originating from CoCrMo‐based implants have been shown to induce a proinflammatory response in macrophages in vitro. Previous studies have also shown that the polarization of macrophages by some proinflammatory stimuli is associated with a hypoxia‐inducible factor‐1α (HIF‐1α)‐dependent metabolic shift from oxidative phosphorylation (OXPHOS) towards glycolysis. However, the potential of Co2+ and Cr3+ to induce this metabolic shift, which plays a determining role in the proinflammatory response of macrophages, remains largely unexplored. We recently demonstrated that Co2+, but not Cr3+, increased oxidative stress and decreased OXPHOS in RAW 264.7 murine macrophages. In the present study, we analyzed the effects of Co2+ and Cr3+ on glycolytic flux and HIF‐1α stabilization in the same experimental model. Cells were exposed to 6 to 24 ppm Co2+ or 50 to 250 ppm Cr3+. Glycolytic flux was determined by analyzing extracellular flux and lactate production, while HIF‐1α stabilization was analyzed by immunoblotting. Results showed that Co2+, and to a lesser extent Cr3+, increased glycolytic flux; however, only Co2+ acted through HIF‐1α stabilization. Overall, these results, together with our previous results showing that Co2+ increases oxidative stress and decreases OXPHOS, suggest that Co2+ (but not Cr3+) can induce a HIF‐1α‐dependent metabolic shift from OXPHOS towards glycolysis in macrophages. This metabolic shift may play an early and pivotal role in the inflammatory response induced by Co2+ in the periprosthetic environment.  相似文献   
108.
PurposeThe purpose of this study was to identify in the EPIRMEX cohort the correlations between MRI brain metrics, including diffuse excessive high signal intensities (DEHSI) obtained with an automated quantitative method and neurodevelopmental outcomes at 2 years.Materials and methodsA total of 390 very preterm infants (gestational age at birth  32 weeks) who underwent brain MRI at term equivalent age at 1.5T (n = 338) or 3T (n = 52) were prospectively included. Using a validated algorithm, automated metrics of the main brain surfaces (cortical and deep gray matter, white matter, cerebrospinal fluid) and DEHSI with three thresholds were obtained. Linear adjust regressions were performed to assess the correlation between brain metrics with the ages and stages questionnaire (ASQ) score at 2 years.ResultsBasal ganglia and thalami, cortex and white matter surfaces positively and significantly correlated with the global ASQ score. For all ASQ sub-domains, basal ganglia and thalami surfaces significantly correlated with the scores. DEHSI was present in 289 premature newborns (74%) without any correlation with the ASQ score. Metrics of DEHSI were greater at 3T than at 1.5T.ConclusionBrain MRI metrics obtained in our multicentric cohort correlate with the neurodevelopmental outcome at 2 years of age. The quantitative detection of DEHSI is not predictive of adverse outcomes. Our automated algorithm might easily provide useful predictive information in daily practice.  相似文献   
109.
IntroductionFibroepithelial polyps (FEP) of the lower urinary tract are relatively common in adults but rare in children, with fewer than 250 cases reported in the literature to date.ObjectiveThe aim of this study was to address the experience of FEP management in children.Study designA retrospective multicenter review was undertaken in children with defined FEP of the lower urinary tract managed between 2008 and 2018. The data at 18 pediatric surgery centers were collected. Their demographic, radiological, surgical, and pathological information were reviewed.ResultsA total of 33 children (26 boys; 7 girls) were treated for FEP of the lower urinary tract at 13 centers. The most common presentation was urinary outflow as hematuria (41%), acute urinary retention (25%), dysuria (19%), or urinary infections (28%). A prenatal diagnosis was made for three patients with hydronephrosis. Almost all of the children (94%) underwent ultrasound imaging of the urinary tract as the first diagnostic examination, 23 (70%) of them also either had an MRI (15%), cystourethrography (25%), computerized tomography (6%), or cystoscopy (45%). Two of these children (6%) had a biopsy prior to the surgery. The median preoperative delay was 7.52 (range: 1–48) months. Most of the patients were treated endoscopically, although four (12.1%) had open surgery and two (6.1%) had an additional incision for specimen extraction. The median hospital stay was 1.5 (range: 1–10) days. There were no recurrences and no complications after a median follow-up of 13 (range: 1–34) months.DiscussionThe main limitation of our study is the retrospective design, although it is the largest one for this pathology.ConclusionThis series supports sonography as the most suitable diagnosis tool before endoscopy to confirm the diagnosis and to perform the resection for most FEP in children. This report confirms the recognized benign nature in the absence of recurrences.Level of EvidenceLevel V.  相似文献   
110.
BACKGROUND: Breast-conservation therapy (BCT), including wide local excision and postoperative irradiation, is considered standard treatment for early-stage invasive ductal carcinoma (IDC). The use of BCT in patients with invasive lobular carcinoma (ILC) has been questioned because of concerns regarding ipsilateral breast recurrence and risk of bilateral breast cancer. We evaluated our institutional experience with BCT and compared treatment outcomes for ILC with those for IDC. METHODS: A review of our BCT database revealed 84 patients with ILC and 1,126 with IDC with stage I or II disease treated with BCT and radiation between 1976 and 1999. We evaluated local-regional recurrence, disease-specific survival, and contralateral breast cancer rates in both groups. RESULTS: The 5- and 10-year local-regional recurrence rates for the ILC group were 1% and 7%, respectively, and 4% and 9%, respectively, for the IDC group (P = .70). There were no significant differences in the 5- and 10-year disease-specific survival rates between the groups. Contralateral breast cancer occurred in 11.3% of patients with IDC and 11.9% of patients with ILC. CONCLUSIONS: BCT achieves similar local-regional control and survival outcomes in selected patients with ILC or IDC. Breast-conservation therapy is an appropriate treatment strategy for patients with early-stage invasive lobular carcinoma.  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