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   1381篇
  免费   78篇
  国内免费   10篇
耳鼻咽喉   2篇
儿科学   20篇
妇产科学   14篇
基础医学   167篇
口腔科学   21篇
临床医学   210篇
内科学   295篇
皮肤病学   24篇
神经病学   116篇
特种医学   48篇
外科学   214篇
综合类   4篇
预防医学   129篇
眼科学   16篇
药学   68篇
肿瘤学   121篇
  2023年   13篇
  2022年   11篇
  2021年   55篇
  2020年   39篇
  2019年   44篇
  2018年   58篇
  2017年   46篇
  2016年   43篇
  2015年   53篇
  2014年   62篇
  2013年   93篇
  2012年   111篇
  2011年   110篇
  2010年   61篇
  2009年   57篇
  2008年   89篇
  2007年   81篇
  2006年   69篇
  2005年   89篇
  2004年   82篇
  2003年   43篇
  2002年   60篇
  2001年   14篇
  2000年   10篇
  1999年   13篇
  1998年   6篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1992年   6篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1987年   3篇
  1986年   6篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1969年   1篇
  1963年   1篇
  1960年   1篇
  1959年   3篇
  1923年   1篇
排序方式: 共有1469条查询结果,搜索用时 15 毫秒
1.
2.
3.
Children and adolescents with major depressive disorder (MDD) appear to be more responsive to placebo than adults in randomized placebo-controlled trials (RCTs) of second and newer generation antidepressants (SNG-AD). Previous meta-analyses obtained conflicting results regarding modifiers. We aimed to conduct a meta-analytical evaluation of placebo response rates based on both clinician-rating and self-rating scales. Based on the most recent and comprehensive study on adult data, we tested whether the placebo response rates in children and adolescents with MDD also increase with study duration and number of study sites. We searched systematically for published RCTs of SNG-AD in children and/or adolescents (last update: September 2017) in public domain electronic databases and additionally for documented studies in clinical trial databases. The log-transformed odds of placebo response were meta-analytically analyzed. The primary and secondary outcomes were placebo response rates at the end of treatment based on clinician-rating and self-rating scales, respectively. To examine the impact of study duration and number of study sites on placebo response rates, we performed simple meta-regression analyses. We selected other potential modifiers of placebo response based on significance in at least one previous pediatric meta-analysis and on theoretical considerations to perform explorative analyses. We applied sensitivity analyses with placebo response rates closest to week 8 to compare our data with those reported for adults. We identified 24 placebo-controlled trials (2229 patients in the placebo arms). The clinician-rated placebo response rates ranged from 22 to 62% with a pooled response rate of 45% (95% CI 41–50%). The number of study sites was a significant modifier in the simple meta-regression analysis [odds ratio (OR) 1.01, 95% CI 1.01–1.02, p = 0.0003, k = 24) with more study sites linked to a higher placebo response. Study duration was not significantly associated with the placebo response rate. The explorative simple analyses revealed that publication year may be an additional modifier. However, in the explorative multivariable analysis including the number of study sites and the publication year only the number of study sites reached a p value ≤ 0.05. The self-rated placebo response rates ranged from 1 to 68% with a pooled response rate of 26% (95% CI 10–54%) (k = 6; n = 396). This meta-analysis confirms a high pooled placebo response rate in children and adolescents based on clinician ratings, which exceeds that observed in the most recent meta-analysis of placebo effects in adults (36%; 95% CI 35–37%) published in 2016. However, and similar to findings in adults, the pooled response rates based on self-ratings were substantially lower. In accordance with previous meta-analyses, we corroborated the number of study sites as significant modifier. In comparison to the recent adult meta-analysis, the substantially lower number of pediatric studies entails a reduced power to detect modifiers. Future studies should provide more precise and homogenous information to support discovery of potential modifiers and consider no-treatment—if ethically permissible—to allow differentiation between placebo and spontaneous remission rates. If these differ, practicing clinicians should facilitate placebo effects as an addition to the verum effect to maximize benefits. Further research is required to explain the discrepant response rates between clinician and self-ratings.  相似文献   
4.
The present study aimed to determine whether an i.c.v. administration of allopregnanolone (ALLO) rapidly modifies the hypothalamic and ovarian 3β‐hydroxysteroid dehydrogenase (3β‐HSD) enzymatic activity and gene expression in in vivo and ex vivo systems in pro‐oestrus (PE) and dioestrus I (DI) rats. Animals were injected with vehicle, ALLO, bicuculline or bicuculline plus ALLO and were then killed. In the in vivo experiment, the hypothalamus, ovaries and serum were extracted and analysed. In the ex vivo experiment, the superior mesenteric ganglion ‐ ovarian nerve plexus ‐ ovary system was extracted and incubated during 120 minutes at 37 ºC. The serum and ovarian compartment fluids were used to determine progesterone by radioimmunoanalysis. In the in vivo experiments, ALLO caused a decrease in hypothalamic and ovarian 3β‐HSD enzymatic activity during PE. During DI, ALLO increased hypothalamic and ovarian 3β‐HSD activity and gene expression. The ovarian 3β‐HSD activity increased in both stages in the ex vivo system; gene expression increased only during DI. ALLO induced an increase in serum progesterone only in D1 and in the ovarian incubation liquids in both stages. All findings were reversed by an injection of bicuculline before ALLO. Ovarian steroidogenic changes could be attributed to signals coming from ganglion neurones, which are affected by the acute central neurosteroid stimulation. The i.c.v. administration of ALLO via the GABAergic system altered 3β‐HSD activity and gene expression, modulating the neuroendocrine axis. The present study reveals the action that ALLO exerts on the GABAA receptor in both the central and peripheral nervous system and its relationship with hormonal variations. ALLO is involved in the “fine tuning” of neurosecretory functions as a potent modulator of reproductive processes in female rats.  相似文献   
5.
In an outbreak of shiga toxin-producing Escherichia coli infections and associated hemolytic-uremic syndrome (STEC O104:H4) in Germany in the year 2011 neurological complications in adult patients occurred unexpectedly frequent, ranging between 48% and 100% in different patient groups. Few is known about the long-term effects of such complications and so we performed follow-up exams on 44 of the patients treated for STEC-HUS at Hannover Medical Scool in this observational study. Standardized follow-up exams including neurological and neuropsychological assessments, laboratory testing, magnetic resonance imaging (MRI), and EEG were carried out. Subgroups were examined 2 (n = 34), 7 (n = 22), and 19 (n = 23) months after disease onset. Additionally, at the 19-month follow-up, quality of life, sleep quality, and possible fatigue were assessed.Nineteen months after disease onset 31 patients were reassessed, 22 of whom still suffered from symptoms such as fatigue, headache, and attention deficits. In the neuropsychological assessments only 39% of the patients performed normal, whereas 61% scored borderline pathological or lower. Upon reviewal, the follow-up data most prominently showed a secondary decline of cognitive function in about one-quarter of the patients. Outcome was not related to treatment or laboratory data in the acute phase of the disease nor length of hospitalization. Prognosis of STEC-HUS associated brain dysfunction in adults with regard to severity of symptoms is mostly good; some patients however still have not made a full recovery. Patients’ caretakers have to be aware of possible secondary decline of brain function as was observed in this study.  相似文献   
6.
7.
8.
Porcine reproductive and respiratory syndrome virus (PRRSV) is prevalent in Danish swine herds. In July 2019, PRRSV‐1 was detected in a PRRSV‐negative boar station and subsequently spread to more than 38 herds that had received semen from the boar station. Full genome sequencing revealed a sequence of 15.098 nucleotides. Phylogenetic analyses showed that the strain was a recombination between the Amervac strain (Unistrain PRRS vaccine; Hipra) and the 96V198 strain (Suvaxyn PRRS; Zoetis AH). The major parent was the 96V198 strain that spanned ORFs 1–2 and part of ORF 3 and the minor parent was the Amervac strain, which constituted the remaining part of the genome. The virus seems to be highly transmissible and has caused severe disease in infected herds despite a high level of genetic identity to the attenuated parent strains. The source of infection was presumable a neighbouring farm situated 5.8 km from the boar station.  相似文献   
9.

Purpose

To evaluate (1) post-discharge healthcare utilization and estimated costs in ARDS survivors, and (2) the association between patient and intensive care-related variables, and 6-month patient status, with subsequent hospitalization and costs.

Methods

Longitudinal cohort study enrolling from four ARDSNet trials in 44 US hospitals. Healthcare utilization was collected via structured interviews at 6 and 12 months post-ARDS, and hospital costs estimated via the Medical Expenditure Panel Survey. Adjusted odds ratios for hospitalization and adjusted relative medians for hospital costs were calculated using marginal two-part regression models.

Results

Of 859 consenting survivors, 839 (98%) reported healthcare utilization, with 52% female and a mean age of 49 years old. Over 12 months, 339 (40%) patients reported at least one post-discharge hospitalization, with median estimated hospital costs of US$18,756 (interquartile range $7852–46,174; 90th percentile $101,500). Of 16 patient baseline and ICU variables evaluated, only cardiovascular comorbidity and length of stay were associated with hospitalization, and sepsis was associated with hospital costs. At 6-month assessment, better patient-reported physical activity and quality of life status were associated with fewer hospitalizations and lower hospital costs during subsequent follow-up, and worse psychiatric symptoms were associated with increased hospitalizations.

Conclusions

This multicenter longitudinal study found that 40% of ARDS survivors reported at least one post-discharge hospitalization during 12-month follow-up. Few patient- or ICU-related variables were associated with hospitalization; however, physical, psychiatric, and quality of life measures at 6-month follow-up were associated with subsequent hospitalization. Interventions to reduce post-ARDS morbidity may be important to improve patient outcomes and reduce healthcare utilization.
  相似文献   
10.

Background

Celiac trunk encasement by adenocarcinoma of the pancreatic body is generally regarded as a contraindication for surgical resection. Recent studies have suggested that a subset of stage III patients will succumb to their disease in the absence of distant metastases. We hypothesized that patients with stage III tumors invading the celiac trunk, who are free of distant disease following neoadjuvant therapy, may derive prolonged survival benefit from aggressive surgical resection.

Methods

We performed a retrospective review of distal pancreatectomies with en bloc celiac axis resection for pancreatic adenocarcinoma.

Results

Eleven patients underwent a distal pancreatectomy with en bloc celiac axis resection after completing neoadjuvant chemoradiation therapy. Median operative time was 8?h, 14?min, and median estimated blood loss was 700?ml. Median length of stay was 9?days. Five patients (45%) had postoperative complications; three were Clavien grade I. Four patients (35%) had pancreatic leaks; two were ISGPF grade B, and two were grade A. There were two 90-day perioperative deaths. Ten patients had R0 resections (91%). After a median follow-up of 41?weeks, six patients recurred. Four of the five patients with SMAD4 loss recurred, and two of the five patients with intact SMAD4 recurred. Median disease-free and overall survival were 21?weeks and 26?months, respectively.

Conclusions

Resection of pancreatic body adenocarcinoma with celiac axis resection is technically feasible with acceptable perioperative morbidity and mortality.  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