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   2135篇
  免费   182篇
  国内免费   5篇
耳鼻咽喉   23篇
儿科学   42篇
妇产科学   53篇
基础医学   253篇
口腔科学   10篇
临床医学   279篇
内科学   425篇
皮肤病学   35篇
神经病学   115篇
特种医学   45篇
外科学   401篇
综合类   13篇
一般理论   1篇
预防医学   212篇
眼科学   28篇
药学   157篇
中国医学   13篇
肿瘤学   217篇
  2023年   31篇
  2022年   73篇
  2021年   133篇
  2020年   59篇
  2019年   94篇
  2018年   90篇
  2017年   60篇
  2016年   71篇
  2015年   82篇
  2014年   104篇
  2013年   125篇
  2012年   155篇
  2011年   150篇
  2010年   73篇
  2009年   68篇
  2008年   108篇
  2007年   129篇
  2006年   83篇
  2005年   77篇
  2004年   83篇
  2003年   76篇
  2002年   70篇
  2001年   36篇
  2000年   35篇
  1999年   25篇
  1998年   13篇
  1997年   4篇
  1996年   9篇
  1995年   4篇
  1994年   8篇
  1993年   5篇
  1992年   17篇
  1991年   20篇
  1990年   31篇
  1989年   14篇
  1988年   14篇
  1987年   8篇
  1986年   17篇
  1985年   12篇
  1984年   11篇
  1983年   5篇
  1982年   3篇
  1981年   4篇
  1979年   2篇
  1976年   4篇
  1975年   3篇
  1974年   5篇
  1973年   4篇
  1968年   2篇
  1966年   2篇
排序方式: 共有2322条查询结果,搜索用时 381 毫秒
1.
Congenital rubella syndrome (CRS) results from maternal rubella virus infection in early pregnancy. Abnormal neuroimaging findings have been analyzed in a small number of CRS patients in the past; however, their clinical significance has been poorly addressed. Therefore, we have investigated the neuroimaging findings of 31 patients with CRS from previous studies. The most common finding was parenchymal calcification, which was observed in 18 of 31 patients (58.1%). A multivariable logistic regression model showed that it was associated with psychomotor or mental retardation (p = 0.018), suggesting that parenchymal calcification in CRS could be a prognostic factor.  相似文献   
2.

Objective

A rapid and worrying emergence of vancomycin-resistant enterococci (VRE) gut colonization is occurring worldwide and may be responsible for outbreaks, especially in healthcare facilities. While no efficient decolonization strategies are recommended, we assessed fecal microbiota transplantation (FMT) to eradicate VRE colonization.

Patients and method

Our main objective was to measure the impact of FMT on decolonization of VRE carriers, confirmed by at least two consecutive negative rectal swabs at one-week interval during a 3-month follow-up period. Patients received no antibiotic prior to the FMT.

Results

After a month only three patients remained colonized with VRE. Decolonization was associated with 87.5% (n = 7) of success after three months as only one patient remained colonized.

Conclusion

Our first results confirm that the FMT seems to be safe, with an impact on VRE colonization over time that may help control outbreaks.  相似文献   
3.
BACKGROUND: The aim of this study was to evaluate long-term results of laparoscopic anterior semifundoplication in patients with nonerosive (NERD) and erosive (ERD) gastroesophageal reflux disease.PATIENTS AND METHODS: The study includes the period from May 1997 to July 2005. Upper gastrointestinal endoscopy was performed in all 190 patients. The severity of reflux esophagitis was classified according to Savary and Miller (grades I-IV). A standardized questionnaire was used for follow-up, and the modified symptomatic DeMeester score was assessed.RESULTS: 58.5 years of age (range 27-80), patients with nonerosive reflux disease (n=83) were significantly older than those with erosive reflux disease (n=107) (48 years range 15-84) (p=0.0001). Patients with NERD had a lower modified symptomatic DeMeester score postoperatively of 0 (range 0-4) than patients with ERD, of 1 (range 0-5), though without statistical significance (p=0.151).CONCLUSION: Laparoscopic anterior semifundoplication leads to comparable symptomatic long-term results in both NERD and ERD. Anterior semifundoplication is a good therapeutic option for selected patients with persistent reflux-associated symptoms and endoscopically negative esophagitis.  相似文献   
4.
Abstract. Twenty-one patients were studied at rest and during exercise after heart transplantation to compare cardiac output measured by thermodilution and impedance cardiography. Exercise was performed on a bicycle ergometer over a limited range of work load (25 and 50 watt) whilst metabolic gas exchange was recorded. One patient was studied at rest whilst his circulation was maintained by a Jarvik-7 artificial heart. The values of cardiac output measured by impedance cardiography corresponded closely with the flow rate from the artificial heart. There was also close agreement between the impedance and thermodilution measurements of cardiac output at rest and during exercise. Both measurements followed the changes in heart rate and oxygen consumption. Both thermodilution and impedance cardiography methods elicited good reproducibility of cardiac output measurements at rest and during exercise. These observations suggest that the noninvasive and continuous record of cardiac output obtained by impedance cardiography can be used for the postoperative monitoring of heart transplant recipients.  相似文献   
5.
The species diversity and genetic structure of mosquitoes belonging to the Anopheles maculatus group in Southeast Asia were investigated using the internal transcribed spacer 2 (ITS2) of ribosomal DNA (rDNA). A molecular phylogeny indicates the presence of at least one hitherto unrecognised species. Mosquitoes of chromosomal form K from eastern Thailand have a unique ITS2 sequence that is 3.7% divergent from the next most closely related taxon (An. sawadwongporni) in the group. In the context of negligible intraspecific variation at ITS2, this suggests that chromosomal form K is most probably a distinct species. Although An. maculatus sensu stricto from northern Thailand and southern Thailand/peninsular Malaysia differ from each other in chromosomal banding pattern and vectorial capacity, no intraspecific variation was observed in the ITS2 sequences of this species over this entire geographic area despite an extensive survey. A PCR-based identification method was developed to distinguish five species of the group (An. maculatus, An. dravidicus, An. pseudowillmori, An. sawadwongporni and chromosomal form K) to assist field-based studies in northwestern Thailand. Sequences from 187 mosquitoes (mostly An. maculatus and An. sawadwongporni) revealed no intraspecific variation in specimens from Thailand, Cambodia, mainland China, Malaysia, Taiwan and Vietnam, suggesting that this identification method will be widely applicable in Southeast Asia. The lack of detectable genetic structure also suggests that populations of these species are either connected by gene flow and/or share a recent common history.  相似文献   
6.
A case of placenta membranacea, previa and accreta was managed conservatively and resulted in delivery of a mature fetus. The diagnosis of placenta membranacea and previa was obtained with ultrasound. The placenta previa and accreta necessitated a cesarean delivery and hysterectomy.  相似文献   
7.
BACKGROUND: The traditional neurotransmitter catecholamine and the neuropeptide tyrosine in sympathetic airway nerves have been proposed to be involved in the pathogenesis of airway diseases. OBJECTIVE: The aim of the present study was to investigate the effect of allergic airway inflammation on the expression of catecholamine enzyme tyrosine hydroxylase (TH), neuropeptide tyrosine (NPY) and tachykinins in mouse sympathetic airway ganglia. METHODS: Using neuronal tracing in combination with immunohistochemistry, the present study was designed to characterize TH, NPY and tachykinin profiles of superior cervical (SCG) and stellate ganglia after allergen challenge. RESULTS: The vast majority of fast blue-labelled SCG neurons (allergen: 97.5+/-1.22% (mean+/-SEM) vs. controls: 94.5+/-1.48%, P=0.18) and stellate neurons (allergen: 95.3+/-1.01% vs. controls: 93.6+/-1.33%, P=0.34) were immunoreactive for TH. Of the TH immunoreactive and fast blue-labelled SCG neurons, 52.0+/-1.01% allergen vs. 51.2+/-3.58% controls (P=0.83) and stellate neurons, 57.3%+/-0.97 allergen vs. 56.4+/-1.65% controls (P=0.64) were positive for TH only but not NPY, whereas 45.3+/-1.05% allergen vs. 43.3+/-1.18% controls (P=0.47) of fast blue-labelled SCG neurons and 37.9+/-0.86% allergen vs. 37.1+/-1.24% controls (P=0.62) of fast blue-labelled stellate neurons were immunoreactive for both TH and NPY immunoreactivities. There was a trend of an increase, but not significant one, in the percentage of TH-/NPY-immunoreactive and fast blue-labelled neurons in allergen-treated animals in comparison with the controls. Tachykinins, however, were not expressed by sympathetic neurons and were also not induced in sympathetic neurons after allergen challenge. CONCLUSION: The present study indicates that allergic airway inflammation does not alter the expression of noradrenalin and NPY in sympathetic ganglia and also shows that sympathetic neurons do not respond to allergic airway inflammation with tachykinins induction. However, a participation of catecholamine and NPY in the pathogenesis of allergic airway inflammation cannot be excluded in the present study as a higher neurotransmitter output per neuron following allergen challenge could be possible.  相似文献   
8.
9.
Follicular lymphomas (FLs) are a heterogeneous group of tumors, but prognostic factors are evaluated insufficiently in this common hematologic neoplasm. While bcl-6 and CD10 are expressed characteristically in FLs, their significance for biologic behavior of FL has not been studied previously. Samples from 73 patients with FL and clinical follow-up from 7 to 231 months were evaluated by immunohistochemical analysis. Patients with high levels of bcl-6 expression had favorable overall survival (OS) (P = .003), disease-specific survival (DSS) (P = .033), and time to treatment failure (P = .003) compared with patients with low levels of bcl-6 expression. Multivariate analysis showed that the results for OS, DSS, and time to treatment failure were independent of the international prognostic index. Patients with CD10+ FLs also had longer OS (P = .001), DSS (P = .007), and time to treatment failure (P = .004), and grade 1 FL was associated with better OS (P = .01) and a statistical trend for longer DSS (P = .05) and time to treatment failure (P = .05), but these results were not independent of bcl-6 expression or the international prognostic index in multivariate analysis.  相似文献   
10.
The variable regions of the heavy and light chains of the protective murine monoclonal antibody (MAb) 2H1 (m2H1) were expressed with the human constant region genes for immunoglobulin G2 (IgG2) and kappa, respectively, to construct a chimeric antibody (ch2H1). ch2H1 retains the specificity of the parent MAb, exhibits biological activity, and lacks the toxicity of the parent murine IgG1 in chronically infected mice.  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