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   1352篇
  免费   108篇
  国内免费   8篇
耳鼻咽喉   3篇
儿科学   37篇
妇产科学   26篇
基础医学   174篇
口腔科学   15篇
临床医学   137篇
内科学   209篇
皮肤病学   6篇
神经病学   196篇
特种医学   9篇
外科学   160篇
综合类   21篇
一般理论   1篇
预防医学   260篇
眼科学   23篇
药学   100篇
中国医学   3篇
肿瘤学   88篇
  2023年   10篇
  2022年   12篇
  2021年   65篇
  2020年   36篇
  2019年   42篇
  2018年   58篇
  2017年   36篇
  2016年   23篇
  2015年   37篇
  2014年   53篇
  2013年   82篇
  2012年   110篇
  2011年   98篇
  2010年   52篇
  2009年   55篇
  2008年   80篇
  2007年   74篇
  2006年   54篇
  2005年   66篇
  2004年   47篇
  2003年   35篇
  2002年   41篇
  2001年   15篇
  2000年   7篇
  1999年   11篇
  1998年   8篇
  1997年   10篇
  1996年   8篇
  1995年   12篇
  1994年   9篇
  1993年   8篇
  1992年   10篇
  1991年   7篇
  1986年   6篇
  1984年   8篇
  1983年   8篇
  1982年   14篇
  1981年   7篇
  1980年   7篇
  1979年   6篇
  1978年   7篇
  1977年   8篇
  1973年   8篇
  1968年   6篇
  1967年   5篇
  1966年   8篇
  1963年   6篇
  1961年   5篇
  1959年   6篇
  1958年   5篇
排序方式: 共有1468条查询结果,搜索用时 46 毫秒
1.
Emergency Radiology - Gallbladder pathology is diverse, and imaging tests are essential tools for its diagnosis. Acute cholecystitis has multiple manifestations or complications, one of which is...  相似文献   
2.

Research question

Previous studies of aromatase inhibitors on male infertility have focused on men with low testosterone–oestradiol ratio of less than 10. Can aromatase inhibitors improve spermatogenesis in men with idiopathic male infertility with normal testosterone–oestradiol ratio?

Design

Prospective study of men with idiopathic severe oligozoospermia (sperm concentration <5 million/ml) carried out between February 2015 and March 2017. The objective was to assess if semen-analysis parameters improved after treatment with letrozole. Secondary objectives were to monitor the safety of letrozole in men, and to measure the alterations in serum FSH, LH, oestradiol and testosterone levels.

Results

Fifteen men with normal testosterone–oestradiol ratio (>10) were treated with letrozole 2.5 mg daily for 4 months. This produced a 5.5-fold increase in sperm concentration (P?=?0.0068). All men had increased total serum testosterone and suppressed oestradiol levels after treatment, thus raising the overall testosterone–oestradiol ratio (P < 0.0001). Adverse effects from letrozole were relatively minor and included loss of libido (54%), headaches (25%), fatigue (21%), weakness (13%), loss of hair (8%) and dry mouth (8%).

Conclusions

Letrozole improves sperm concentration and increases testosterone–oestradiol ratio for men with oligozoospermia who have normal testosterone–oestradiol ratio; its role in the treatment of male infertility may be extended to this group of patients. In addition, it is a relatively well-tolerated drug with no serious adverse effects.  相似文献   
3.
PurposeManagement of head and neck cancers (HNC) in older adults is a common but challenging clinical scenario. We assess the impact of Stereotactic Body Radiation Therapy (SBRT) on survival utilizing the Geriatric-8 (G8) questionnaire.Materials and methods171 HNC patients, deemed medically unfit for definitive treatment, were treated with SBRT ± systemic therapy. G8 questionnaires were collected at baseline, at 4–6 weeks, and at 2–3 months post-treatment. Patients were stratified according to their baseline G8 score: <11 as ‘vulnerable’, 11–14 as ‘intermediate’, and >14 as ‘fit’. Overall survival (OS) was assessed through univariate Kaplan Meier analysis. Repeated measures ANOVA was used to determine if baseline characteristics affected G8 score changes.ResultsMedian follow-up was seventeen months. 60% of patients presented with recurrent HNC, 30% with untreated HNC primaries, and 10% with metastatic non-HNC primaries. Median age was 75 years. Median Charlson Comorbidity Index score was 2. 51% of patients were ‘vulnerable’, 37% were ‘intermediate’, and 12% were ‘fit' at baseline, with median survival of 13.2, 24.3, and 41.0 months, respectively (p = .004). Patients who saw a decrease in their follow-up G8 score (n = 69) had significantly lower survival than patients who had stable or increased follow-up G8 scores (n = 102), with median survival of 8.6 vs 36.0 months (p < .001).ConclusionThe G8 questionnaire may be a useful tool in upfront treatment decision-making to predict prognosis and prevent older patients from receiving inappropriate anti-cancer treatment. Decline in follow-up G8 scores may also predict worse survival and aid in goals of care following treatment.  相似文献   
4.
ABSTRACT

The lack of stable housing can impair access and continuity of care for patients living with human immunodeficiency virus (HIV). This study investigated the relationship between housing status assessed at multiple time points and several core HIV-related outcomes within the same group of HIV patients experiencing homelessness. Patients with consistently stable housing (CSH) during the year were compared to patients who lacked CSH (non-CSH group). The study outcomes included HIV viral load (VL), CD4 counts, and health care utilization. Multivariable and propensity weighted analyses were used to assess outcomes adjusting for potential group differences. Of 208 patients, 88 (42%) had CSH and 120 (58%) were non-CSH. Patients with CSH had significantly higher proportion of VL suppression and higher mean CD4 counts. The frequency of nurse visits in the CSH group was less than a half of that in the non-CSH group. Patients with CSH were less likely to be admitted to the medical respite facility, and if admitted, their length of stay was about a half of that for the non-CSH group. Our study findings show that patients with CSH had significantly better HIV virologic control and immune status as well as improved health care utilization.  相似文献   
5.
International Journal of Paediatric Dentistry 2011; Background. Physiological root resorption differentiates primary from permanent teeth. The understanding of what protects and regulates root resorption might help to develop therapies to its control. Aim. To verify the presence and distribution of ECRM and the expression of CK14, OPG, TRAP and COX‐2 in the periodontal ligament (PDL) of human primary and permanent teeth. Design. Eight primary teeth undergoing physiological or pathological root resorption and 4 permanent teeth were immunohistochemically processed for CK14, TRAP, COX‐2 and OPG expression. Results. PDL from primary and permanent teeth showed similar morphological features; however, fewer ECRM clusters and higher immunoreactivity to CK14 were found in primary PDL. In permanent teeth, ECRM were distributed along the entire PDL tissue. Howship′s lacunae were found only in primary teeth, associated with the presence of TRAP‐positive cells and increase in COX‐2 expression. OPG expression in primary PDL was detected in nonresorptive cervical areas and in lacunae showing reparative tissue. It was observed higher expression of OPG in all permanent teeth when compared to primary specimens. Conclusions. It may be concluded that PDL from primary teeth shows less ECRM clusters and lower expression of OPG. These features may be associated with lower protection against root resorption in primary teeth.  相似文献   
6.

Introduction

Mineral trioxide aggregate (MTA) and calcium hydroxide [Ca(OH)2] are promising biomaterials for stimulating dentinogenesis and cementogenesis. This research was undertaken to understand how MTA and CA(OH)2 participate in the inflammatory, healing, and biomineralization processes. In this part of the study, we evaluated inflammatory signaling molecules promoted by in vivo host interaction with MTA and Ca(OH)2.

Methods

Human dentin tubes were filled with ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), Ca(OH)2, or kept empty. After 12 hours and 1, 3, 7, 15, 30, and 60 days of implantation in subcutaneous tissues in the backs of mice, the tubes and surrounding tissues were retrieved for cytokine level quantification and histological and immunohistochemical analysis.

Results

MTA and Ca(OH)2 induced proinflammatory cytokine up-regulation for up to 3 days. Moreover, interleukin-10 overexpression was noted on the tissue in contact with the biomaterials during the acute phase of the inflammatory reaction. Immunohistochemical analyses showed an increased expression of myeloperoxidase, nuclear factor kappa B (NF-κB), cyclooxygenase-2, inducible nitric oxide synthase enzymes, and vascular endothelial growth factor on day 1 for all groups.

Conclusions

MTA and Ca(OH)2 increased the activation of the NF-κB signaling system on day 1 for all groups. This finding can be associated with a proinflammatory and pro-wound healing environment, which was promoted earlier by MTA.  相似文献   
7.
Efforts to understand nervous system structure and function have received new impetus from the federal Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Comparative analyses can contribute to this effort by leading to the discovery of general principles of neural circuit design, information processing, and gene‐structure‐function relationships that are not apparent from studies on single species. We here propose to extend the comparative approach to nervous system ‘maps' comprising molecular, anatomical, and physiological data. This research will identify which neural features are likely to generalize across species, and which are unlikely to be broadly conserved. It will also suggest causal relationships between genes, development, adult anatomy, physiology, and, ultimately, behavior. These causal hypotheses can then be tested experimentally. Finally, insights from comparative research can inspire and guide technological development. To promote this research agenda, we recommend that teams of investigators coalesce around specific research questions and select a set of ‘reference species' to anchor their comparative analyses. These reference species should be chosen not just for practical advantages, but also with regard for their phylogenetic position, behavioral repertoire, well‐annotated genome, or other strategic reasons. We envision that the nervous systems of these reference species will be mapped in more detail than those of other species. The collected data may range from the molecular to the behavioral, depending on the research question. To integrate across levels of analysis and across species, standards for data collection, annotation, archiving, and distribution must be developed and respected. To that end, it will help to form networks or consortia of researchers and centers for science, technology, and education that focus on organized data collection, distribution, and training. These activities could be supported, at least in part, through existing mechanisms at NSF, NIH, and other agencies. It will also be important to develop new integrated software and database systems for cross‐species data analyses. Multidisciplinary efforts to develop such analytical tools should be supported financially. Finally, training opportunities should be created to stimulate multidisciplinary, integrative research into brain structure, function, and evolution. J. Comp. Neurol. 522:1445–1453, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
8.

Background

Relapses upon corticosteroids tapering and immunosuppressive agents are frequent in Takayasu arteritis (TA). Interleukin-6 is highly involved in physiopathology of TA. Many reports showed efficacy of tocilizumab (TCZ) in refractory TA cases. We report four cases and an updated literature review on the TCZ efficacy and safety in patients with TA.

Methods

Patients with TA defined by ACR 1990 criteria were included. Clinical, biological and imaging data were retrospectively reported. Disease activity was analyzed before TCZ and during the follow-up. Medline database was searched for systematic literature review.

Results

One hundred and five patients (median age 28 years [22–38]) were included, mostly refractory cases (76 patients, 72%). Median TCZ duration was 12 months [6–20]. Among 105 patients, 90 patients (85.7%) had an initial clinical response within three months [3–6] and 43/66 patients (65.2%) had a radiological improvement. Only seven patients (9%) showed relapse on therapy. Corticosteroid dose reduction was obtained in 75/83 patients (90.4%). Relapse after TCZ discontinuation was observed in six patients (46%), with a median time of five months [2–9]. Twenty-four side-effects were noted in 18 patients (18%), with TCZ interruption in seven cases (7%): 10 infections, five cytopenia, six hepatitis, one pancreatitis, one cutaneous rash and one breast cancer.

Conclusions

This review confirms that TCZ is safe and effective in refractory cases of TA and TCZ is a corticosteroid-sparing therapy in patients with or without previous TNFα blockers therapy. However relapses after TCZ discontinuation are frequent.  相似文献   
9.

Background

The Joint Trauma System has demonstrated improved outcomes through coordinated research and process improvement programs. With fewer combat trauma patients, our military American College of Surgeons level 2 trauma center’s ability to maintain a strong trauma Process Improvement (PI) program has become difficult. As emergency general surgery (EGS) patients are similar to trauma patients, our Trauma and Acute Care Surgery (TACS) service developed an EGS PI program analogous to what is done in trauma. We describe the implementation of our novel EGS PI program and its effect on institutional PI proficiency.

Methods

An EGS registry was developed in 2013. Inclusion criteria were based on AAST published literature. In 2015, EGS registrar and PI coordinator positions were developed and filled with existing trauma staff. A formal EGS PI program began January 1, 2016. Pre- and post-program data was compared to determine the effect including EGS PI events had on increasing yield into our trauma PI program.

Results

In 2016, TACS saw 1001 EGS consults. Four hundred forty-four met criteria for registry inclusion. Eighty-two patients had 131 PI events; re-admission within 30 days, unplanned therapeutic intervention, and unplanned ICU admission were the most common events. Capture of EGS PI events yielded a 49% increase compared with 2015.

Conclusion

Overall patient volume and PI events post EGS PI program initiation exceeded those prior to implementation. These data suggest that extending trauma PI principles to EGS may be beneficial in maintaining inter-war military and/or lower volume trauma center readiness.
  相似文献   
10.
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