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   10477篇
  免费   688篇
  国内免费   46篇
耳鼻咽喉   188篇
儿科学   309篇
妇产科学   226篇
基础医学   1432篇
口腔科学   556篇
临床医学   864篇
内科学   2210篇
皮肤病学   300篇
神经病学   935篇
特种医学   200篇
外科学   1332篇
综合类   65篇
一般理论   1篇
预防医学   997篇
眼科学   298篇
药学   745篇
中国医学   63篇
肿瘤学   490篇
  2023年   99篇
  2022年   207篇
  2021年   392篇
  2020年   249篇
  2019年   365篇
  2018年   435篇
  2017年   290篇
  2016年   287篇
  2015年   362篇
  2014年   449篇
  2013年   565篇
  2012年   796篇
  2011年   827篇
  2010年   473篇
  2009年   367篇
  2008年   539篇
  2007年   576篇
  2006年   475篇
  2005年   446篇
  2004年   378篇
  2003年   356篇
  2002年   294篇
  2001年   201篇
  2000年   231篇
  1999年   181篇
  1998年   64篇
  1997年   52篇
  1996年   29篇
  1995年   28篇
  1994年   41篇
  1993年   34篇
  1992年   128篇
  1991年   110篇
  1990年   100篇
  1989年   80篇
  1988年   77篇
  1987年   54篇
  1986年   67篇
  1985年   67篇
  1984年   38篇
  1983年   35篇
  1982年   27篇
  1981年   21篇
  1980年   18篇
  1979年   33篇
  1978年   34篇
  1976年   18篇
  1974年   21篇
  1969年   17篇
  1967年   21篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
81.
Conflicting data concerning the association between obesity and differentiated thyroid cancer (DTC) may be attributed to the lack of records showing dietary intake and inadequate evaluation of nutrient composition. We evaluated 115 DTC patients carefully paired with 103 healthy control individuals by using a structured questionnaire, including a 24-h recordatory during 3 days, to investigate calorie intake and macronutrient (proteins, carbohydrates, and lipids) composition of the diet. We observed that excess weight (body mass index > 25 kg/m2) increased individual susceptibility to DTC [odds ratio (OR) = 3.787; 95% confidence interval (CI) = 1.115–6.814; P < 0.0001). This augmented risk was evident in women (OR = 1.925; 95% CI = 1.110–3.338; P = 0.0259) but not in men (P = 0.3498). Excess calorie intake was more frequent in patients with DTC than in controls (OR = 5.890; 95% CI = 3.124–11.103; P < 0.0001), and both excess protein (OR = 4.601; 95% CI = 1.634–12.954; P = 0.0039) and carbohydrate (OR = 4.905; 95% CI = 2.593–9.278; P < 0.0001) consumption were associated with an increased risk of DTC, contrarily to lipid/fiber intake and physical activity (P = 0.894 and 0.5932, respectively). In conclusion, our data indicate that overweight and risk of DTC are associated with higher protein and carbohydrate consumption than the rates recommended by the World Health Organization. The nutritional orientation should be part of preventive strategy targets designed to combat the increasing incidence of both obesity and DTC.  相似文献   
82.
83.
84.
85.
OBJECTIVES: Diagnostic accuracy of the ThinPrep process (Cytyc, Boxborough, MA) was compared with that of conventional (smear) cytopreparation for fine-needle aspiration (FNA) of head and neck masses. METHODS: In a prospective, randomized, single-blinded study, 209 patients served as their own controls and underwent 236 FNAs using ThinPrep and conventional (smear) cytopreparatory techniques. RESULTS: ThinPrep produced less air-drying artifact and less mechanical distortion than the conventional method. The conventional technique was diagnostic in 63% of samples; the ThinPrep technique was diagnostic in 55% of samples. When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cytopreparatory technique for most head and neck masses. CONCLUSIONS: For adequately experienced cytopathologists, ThinPrep is acceptable for FNA of salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions. Conventional smear technique should be used for FNA of nonmetastatic lymphoid lesions. Use of ThinPrep can complement use of the conventional (smear) cytopreparatory technique when aspirate is nondiagnostic or bloody, when the patient has a blood-borne infectious disease, when the clinician is inexperienced, or when aspirate has entered the syringe.  相似文献   
86.

Background

Renal failure is the most important comorbidity in patients with heart transplantation, it is associated with increased mortality. The major cause of renal dysfunction is the toxic effects of calcineurin inhibitors (CNI). Sirolimus, a proliferation signal inhibitor, is an imunossupressant recently introduced in cardiac transplantation. Its nonnephrotoxic properties make it an attractive immunosuppressive agent for patients with renal dysfunction. In this study, we evaluated the improvement in renal function after switching the CNI to sirolimus among patients with new-onset kidney dysfunction after heart transplantation.

Methods

The study included orthotopic cardiac transplant (OHT) patients who required discontinuation of CNI due to worsening renal function (creatinine clearance < 50 mL/min). We excluded subjects who had another indication for initiation of sirolimus, that is, rejection, malignancy, or allograft vasculopathy. The patients were followed for 6 months. The creatinine clearance (CrCl) was estimated according to the Cockcroft-Gault equation using the baseline weight and the serum creatinine at the time of introduction of sirolimus and 6 months there after. Nine patients were included, 7 (78%) were males and the overall mean age was 60.1 ± 12.3 years and time since transplantation 8.7 ± 6.1 years. The allograft was beyond 1 year in all patients. There was a significant improvement in the serum creatinine (2.98 ± 0.9 to 1.69 ± 0.5 mg/dL, P = .01) and CrCl (24.9 ± 6.5 to 45.7 ± 17.2 mL/min, P = .005) at 6 months follow-up.

Conclusion

The replacement of CNI by sirolimus for imunosuppressive therapy for patients with renal failure after OHT was associated with a significant improvement in renal function after 6 months.  相似文献   
87.
Histoplasmosis is a rarely reported deep mycotic infection in the Indian context. Oral or oropharyngeal manifestation can occur as an isolated symptom or as part of a disseminated process associated with immunosuppression especially with HIV and diabetes. Five cases of head and neck histoplasmosis accrued over 6 years in a tertiary referral cancer institute were reviewed. All these patients presented clinically as cancer. In three patients, the marked pseudoepitheliomatous hyperplasia led to a mistaken biopsy diagnosis of malignancy following which definitive surgical treatment was performed. The subsequent excision revealed typical features of histoplasmosis. Isolated oral presentation of histoplasmosis can mimic malignancy both clinically as well as pathologically, leading to potentially disastrous consequences. A high index of suspicion in those with overt or hidden immunosuppression and a deep wedge biopsy to demonstrate the organisms in the subepithelial tissue is recommended. This work has been presented in the “Slide seminar on Infections and Infestations” in the IAP-ID pre conference CME in APCON 2006.  相似文献   
88.
Conditional mouse knock-outs provide an informative approach to drug target validation where no pharmacological blockers exist or global knock-outs are lethal. Here, we used the Cre-loxP system to delete BDNF in most nociceptive sensory neurons. Conditional null animals were healthy with no sensory neuron loss. However, pain-related behavior was substantially altered. Baseline thermal thresholds were reduced. Carrageenan-induced thermal hyperalgesia was inhibited. Formalin-induced pain behavior was attenuated in the second phase, and this correlated with abolition of NMDA receptor NR1 Ser896/897 phosphorylation and ERK1 and ERK2 activation in the dorsal horn; AMPA receptor phosphorylation (GluR1/Ser831) was unaffected. NGF-induced thermal hyperalgesia was halved, and mechanical secondary hyperalgesia caused by intramuscular NGF was abolished. By contrast, neuropathic pain behavior developed normally. Nociceptor-derived BDNF thus plays an important role in regulating inflammatory pain thresholds and secondary hyperalgesia, but BDNF released only from nociceptors plays no role in the development of neuropathic pain.  相似文献   
89.

Background

Neurogenic detrusor overactivity (NDO) frequently results in urinary incontinence (UI) which impairs quality of life (QOL) and puts the upper urinary tract at risk.

Objective

To assess the effects of onabotulinumtoxinA (BOTOX®, Allergan, Inc.) on UI, urodynamic variables, and QOL in incontinent patients with NDO.

Design, setting, and participants

This multicentre, randomised, double-blind, placebo-controlled study enrolled patients with multiple sclerosis (MS; n = 154) or spinal cord injury (SCI; n = 121) with UI due to NDO (≥14 UI episodes per week).

Intervention

Patients received 30 intradetrusor injections of onabotulinumtoxinA 200 U (n = 92), 300 U (n = 91), or placebo (n = 92), avoiding the trigone.

Measurements

Primary end point was change from baseline in UI episodes per week (week 6). Secondary end points included urodynamics (maximum cystometric capacity [MCC], maximum detrusor pressure during first involuntary detrusor contraction [PdetmaxIDC]), and Incontinence Quality of Life (I-QOL) total score. Adverse events (AEs) were assessed.

Results and limitations

At baseline, mean UI episodes per week (33.5) were similar across groups. At week 6, onabotulinumtoxinA 200 U and 300 U significantly reduced UI episodes per week (−21.8 and −19.4, respectively) compared with placebo (−13.2; p < 0.01); onabotulinumtoxinA benefit was observed by the first posttreatment study visit at week 2. Improvements in MCC, PdetmaxIDC, and I-QOL at week 6 were significantly greater with both onabotulinumtoxinA doses than with placebo (p < 0.001). Benefits were observed in both the MS and SCI populations. The median time to patient request for retreatment was the same for both onabotulinumtoxinA doses (42.1 wk) and greater than placebo (13.1 wk; p < 0.001). Most frequent AEs were localised urologic events (urinary tract infections and urinary retention, which were dose related in patients not using clean intermittent catheterisation [CIC] at baseline). Significant increases in postvoid residual were observed in patients not using CIC prior to treatment, and 12%, 30%, and 42% of patients in the placebo, 200-U, and 300-U groups, respectively, initiated CIC posttreatment.

Conclusions

OnabotulinumtoxinA significantly reduced UI and improved urodynamics and QOL in MS and SCI patients with NDO. Both doses were well tolerated with no clinically relevant differences in efficacy or duration of effect between the two doses (http://www.clinicaltrials.gov; NCT00461292).  相似文献   
90.
Acute kidney injury (AKI) is an independent risk factor for mortality in critically ill patients whose epidemiology has been made unclear in the past by the use of different definitions across various studies. The RIFLE consensus definition has provided a unifying definition for AKI leading to large retrospective studies in different countries. The present study is a prospective observational multicenter study designed to prospectively evaluate all incident admissions in 10 Intensive Care Units (ICUs) in Italy and the relevant epidemiology of AKI. A simple user-friendly web-based data collection tool was created with the scope to serve for this study and to facilitate future multicenter collaborative efforts. We enrolled 601 consecutive patients into the study; 25 patients with End-Stage Renal Disease were excluded leaving 576 patients for analysis. The median age was 66 (IQR 53-76) years, 59.4% were male, while median SAPS II and APACHE II scores were 43 (IQR 35-54) and 18 (IQR 13-24), respectively. The most common diagnostic categories for ICU admission were: respiratory (27.4%), followed by neurologic (17%), trauma (14.4%), and cardiovascular (12.1%). Crude ICU and hospital mortality were 21.7% and median ICU length of stay was 5 days (IQR 3, 14). Of 576 patients, 246 patients (42.7%) had AKI within 24 hours of ICU admission while 133 developed new AKI later during their ICU stay. RIFLE-initial class was Risk in 205 patients (54.1%), Injury in 99 (26.1%) and Failure in 75 (19.8%). Progression of AKI to a worse RIFLE class was seen in 114 patients (30.8% of AKI patients). AKI patients were older, with higher frequency of common risk factors. 116 AKI patients (30.6%) fulfilled criteria for sepsis during their ICU stay, compared to 33 (16.7%) of non-AKI patients (P<0.001). 48 patients (8.3%) were treated with renal replacement therapy (RRT) in the ICU. Patients were started on RRT a median of 2 (IQR 0-6) days after ICU admission. Among AKI patients, they were started on RRT a median of 1 (IQR 0-4) days after fulfilling criteria for AKI. Median duration of RRT was 5 (IQR 2-10) day. AKI patients had a higher crude ICU mortality (28.8% vs. non-AKI 8.1%, P<0.001) and longer ICU length of stay (median 7 days vs. 3 days [non-AKI], P<0.001). Crude ICU mortality and ICU length of stay increased with greater severity of AKI. Two hundred twenty five patients (59.4% of AKI patients) had complete recovery of renal function, with a SCr at time of ICU discharge which was ≤120% of baseline; an additional 51 AKI patients (13.5%) had partial renal recovery, while 103 (27.2%) had not recovered renal function at the time of death or ICU discharge. Septic patients had more severe AKI, and were more likely to receive RRT with less frequency of renal function recovery. Patients with sepsis had higher ICU mortality and longer ICU stay. The study confirms previous analyses describing RIFLE as an optimal classification system to stage AKI severity. AKI is indeed a deadly complication for ICU patients where the level of severity correlated with mortality and length of stay. The tool developed for data collection resulted user friendly and easy to implement. Some of its features including a RIFLE class alert system, may help the treating physician to collect systematically AKI data in the ICU and possibly may guide specific decision on the institution of renal replacement therapy.  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