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   1540篇
  免费   112篇
  国内免费   98篇
耳鼻咽喉   37篇
儿科学   97篇
妇产科学   20篇
基础医学   175篇
口腔科学   41篇
临床医学   234篇
内科学   289篇
皮肤病学   30篇
神经病学   102篇
特种医学   123篇
外科学   127篇
综合类   68篇
一般理论   20篇
预防医学   150篇
眼科学   23篇
药学   145篇
肿瘤学   69篇
  2021年   15篇
  2018年   16篇
  2017年   11篇
  2015年   12篇
  2014年   22篇
  2013年   44篇
  2012年   48篇
  2011年   39篇
  2010年   46篇
  2009年   42篇
  2008年   45篇
  2007年   88篇
  2006年   43篇
  2005年   63篇
  2004年   43篇
  2003年   45篇
  2002年   46篇
  2001年   31篇
  2000年   21篇
  1999年   27篇
  1998年   61篇
  1997年   43篇
  1996年   44篇
  1995年   38篇
  1994年   40篇
  1993年   50篇
  1992年   29篇
  1991年   37篇
  1990年   35篇
  1989年   49篇
  1988年   45篇
  1987年   29篇
  1986年   38篇
  1985年   28篇
  1984年   24篇
  1983年   23篇
  1982年   17篇
  1981年   28篇
  1980年   24篇
  1979年   14篇
  1978年   26篇
  1977年   24篇
  1976年   13篇
  1975年   13篇
  1974年   12篇
  1970年   11篇
  1969年   18篇
  1966年   10篇
  1965年   13篇
  1955年   10篇
排序方式: 共有1750条查询结果,搜索用时 15 毫秒
21.
22.
Equine herpesvirus-1 (EHV-1) strains with a single point mutation at the 2254 nucleotide position with a G2254 constitution within the DNA polymerase gene are associated strongly with equine myeloencephalopathies. Infections with non-neuropathogenic EHV-1 strains without the G2254 nucleotide but with an A2254 nucleotide are associated less frequently with equine neurologic disease. A retrospective study utilizing DNA extracted from formalin fixed paraffin embedded tissues was conducted with real time PCR and pyrosequencing, to determine the infecting EHV-1 strains. Infection with EHV-1 A2254 and or G2254 strain was detected with real time PCR, and was confirmed with a rapid pyrosequencing technique. Pyrosequencing was useful in at least 2 cases where real time PCR was equivocal in determining the infecting EHV-1 strain type. The strain with G2254 mutation was detected in 9.4% of 21 studied abortion cases, and in 86.6% of 15 neurologic cases.  相似文献   
23.
This report describes a new method based on roentgen videodensitometry for the measurement of left ventricular ejection fraction in man. The net forward ejection fraction (NFEF) is calculated directly from the formula NFEF = 1-exp (?.693/N), where N is the number of cardiac cycles necessary for half of the injected contrast material to be washed out of the left ventricle. The derivation of this formula is presented, and the technique is validated by comparison with washout curves from a Lucite model of the heart and with simultaneous angiographically determined left ventricular ejection fractions in man. The videodensitometry technique offers the following advantages over the conventional volume technique: (1) only a small amount of contrast material is required; (2) ectopic beats are uncommon during the washout phase when measurements are made; (3) the ejection fraction measured is an average of several cardiac cycles; and (4) dependence upon operator interpretation is minimized. Furthermore, given adequate mixing within the chamber, NFEF should be independent of ventricular geometry. Thus, NFEF of the unusually shaped left ventricle can be readily determined.  相似文献   
24.
25.
26.
Abstract: The prevalence of Parkinson’s disease (PD) is expected to double over the next 20 years owing to the increase in life expectancy. This progressive disease has several implications relating to oral health, and many are manageable with proper awareness and knowledge about the disease. This article reviews the epidemiology, pathophysiology, and characteristics of PD, as well as the treatments and oral health considerations to enable dental hygienists to undertake an informed approach to patient management strategies and provide optimal care.  相似文献   
27.

Introduction

The high mortality and morbidity associated with resection for oesophagogastric malignancy has resulted in a conservative approach to the postoperative management of this patient group. In August 2009 we introduced an enhanced recovery after surgery (ERAS) pathway tailored to patients undergoing resection for oesophagogastric malignancy. We aimed to assess the impact of this change in practice on standard clinical outcomes.

Methods

Two cohorts were studied of patients undergoing resection for oesophagogastric malignancy before (August 2008 – July 2009) and after (August 2009 – July 2010) the implementation of the ERAS pathway. Data were collected on demographics, interventions, length of stay, morbidity and in-hospital mortality.

Results

There were 53 and 55 oesophagogastric resections undertaken respectively for malignant disease in each of the study periods. The median length of stay for both gastric and oesophageal resection decreased from 15 to 11 days (Mann– Whitney U, p<0.001) following implementation of the ERAS pathway. There was no significant increase in morbidity (gastric resection 23.1% vs 5.3% and oesophageal resection 25.9% vs 16.7%) or mortality (gastric resection no deaths and oesophageal resection 1.8% vs 3.6%) associated with the changes. There was a significant decrease in the number of oral contrast studies used following oesophageal resection, with a reduction from 21 (77.8%) in 2008–2009 to 6 (16.7%) in 2009–2010 (chi-squared test, p<0.0001).

Conclusions

The introduction of an enhanced recovery programme following oesophagogastric surgery resulted in a significant decrease in length of median patient stay in hospital without a significant increase in associated morbidity and mortality.  相似文献   
28.
Small instestinal submucosa (SIS) is an easily produced material that has been used experimentally for tissue engineering. To evaluate the ability of SIS to facilitate bone growth within a long-bone defect, a segment of the radius was surgically removed in adult, female Sprague-Dawley rats. The defect was either left unfilled or implanted with SIS, demineralized cortical bone (DMCB), or ovalbumin. The defect was evaluated radiographically and histologically after 3, 6, 12, and 24 weeks. Tissue remodeling within the defect was evident by week 3 in SIS- and DMCB-treated rats. Filling was characterized initially by infiltration of mononuclear cells and extracellular material in SIS-implanted rats and multifocal remodeling bone particles and cartilage formation in DMCB implanted rats. Cartilage was observed as early as 3 weeks and bone as early as 6 weeks in SIS-implanted rats. Filling of the defect arose from multiple foci in DMCB-implanted rats, but was contiguous with and parallel to the ulnar shaft in SIS-implanted rats, suggesting that defect repair by SIS may be conductive rather than inductive. Rats in which the defect was left unfilled demonstrated slow but progressive filling of the defect, characterized by mononuclear cell infiltrates and fibrous extracellular material. In summary, SIS facilitated rapid filling of a longbone defect. These results suggest that SIS may be useful as a bone repair material.  相似文献   
29.
30.
Among infertile men, a diagnosis of unilateral varicocele is made in 90% of varicocele cases and bilateral in the remaining varicocele cases. However, there are reports of under-diagnosis of bilateral varicocele among infertile men and that its prevalence is greater than 10%. In this prospective study, we aimed to examine the differentially expressed proteins (DEP) extracted from spermatozoa cells of patients with bilateral varicocele and fertile donors. Subjects consisted of 17 men diagnosed with bilateral varicocele and 10 proven fertile men as healthy controls. Using the LTQ-orbitrap elite hybrid mass spectrometry system, proteomic analysis was done on pooled samples from 3 patients with bilateral varicocele and 5 fertile men. From these samples, 73 DEP were identified of which 58 proteins were differentially expressed, with 7 proteins unique to the bilateral varicocele group and 8 proteins to the fertile control group. Majority of the DEPs were observed to be associated with metabolic processes, stress responses, oxidoreductase activity, enzyme regulation, and immune system processes. Seven DEP were involved in sperm function such as capacitation, motility, and sperm-zona binding. Proteins TEKT3 and TCP11 were validated by Western blot analysis and may serve as potential biomarkers for bilateral varicocele. In this study, we have demonstrated for the first time the presence of DEP and identified proteins with distinct reproductive functions which are altered in infertile men with bilateral varicocele. Functional proteomic profiling provides insight into the mechanistic implications of bilateral varicocele-associated male infertility.  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