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   367篇
  免费   19篇
  国内免费   14篇
儿科学   18篇
妇产科学   7篇
基础医学   33篇
口腔科学   9篇
临床医学   35篇
内科学   83篇
皮肤病学   5篇
神经病学   11篇
特种医学   126篇
外科学   31篇
综合类   7篇
预防医学   7篇
眼科学   8篇
药学   12篇
肿瘤学   8篇
  2021年   1篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   7篇
  2014年   6篇
  2013年   7篇
  2012年   5篇
  2011年   9篇
  2010年   6篇
  2009年   17篇
  2008年   11篇
  2007年   9篇
  2006年   7篇
  2005年   11篇
  2004年   5篇
  2003年   3篇
  2002年   2篇
  2001年   6篇
  2000年   3篇
  1999年   9篇
  1998年   20篇
  1997年   24篇
  1996年   22篇
  1995年   11篇
  1994年   16篇
  1993年   7篇
  1992年   8篇
  1991年   3篇
  1990年   6篇
  1989年   11篇
  1988年   10篇
  1987年   11篇
  1986年   11篇
  1985年   15篇
  1984年   5篇
  1983年   17篇
  1982年   17篇
  1981年   15篇
  1980年   10篇
  1979年   3篇
  1978年   6篇
  1977年   11篇
  1976年   6篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1970年   1篇
排序方式: 共有400条查询结果,搜索用时 15 毫秒
11.
Over the past 15 years, the use of β-agonists has declined worldwide. Following the Royal College of Obstetricians and Gynaecologists guidelines in 2002, clinicians in the UK and beyond were faced with the dilemma of continuing to use β-agonists, desist from using tocolytic therapy completely or choosing to change to atosiban or calcium channel blockers (CCBs). While grade A level 1 evidence exists to show that atosiban is significantly more efficacious than placebo and significantly safer than β-agonists for the treatment of spontaneous preterm labour, the evidence for CCBs, such as nifedipine, is much less robust and no placebo-controlled trials have been performed. Published studies on nifedipine are largely investigator-led studies of small sample size, which lack sufficient power. As a result, most of the evidence has been based on meta-analyses of these studies, which look retrospectively at pooled data and are only as good as the quality of the studies included. In light of this, a tool was developed to produce a systematic review of studies on tocolytic effectiveness, which can and should be applied to all tocolytics and which considered both method- and topic-specific markers of quality. In the process of applying this tool to nifedipine, an extensive literature search identified 31 studies for a systematic review of the quality of nifedipine studies assessed by eight paired reviewers with wide experience in the subject of spontaneous preterm labour and preterm birth. Forty topic- and method-specific items of quality were assessed. The paucity of good quality studies of nifedipine used for the treatment of spontaneous preterm labour should be highlighted in meta-analyses or systematic reviews, which measure efficacy and should limit and influence the degree to which recommendations and guidelines are made on the basis of such studies.  相似文献   
12.
Petrequin  PR; Todd  RF d; Smolen  JE; Boxer  LA 《Blood》1986,67(4):1119-1125
The widespread assumption that cytoplasts generated from human polymorphonuclear leukocytes (PMNs) are vesicles consisting solely of cytoplasm surrounded by plasma membrane and devoid of granule activity remains to be tested. PMN cytoplasts were prepared by centrifugation of intact cells on a Ficoll step gradient in the presence of cytochalasin B. Two granule membrane markers, Mol, a fluorometrically detectable antigen, and cytochrome b, both of which have been shown to translocate to the plasma membrane during granule release, were compared for their activity in cytoplasts and intact PMNs. We found that the amount of Mol detected on the plasma membrane of intact PMNs, as compared with other membrane markers (such as antigens LFA-1 and beta 2m), increased 1.6- fold upon exposure of PMNs to Ficoll plus cytochalasin B prior to centrifugation. Another twofold increase in Mol expression occurred upon cytoplast preparation. Release of the granule enzymes, vitamin B12- binding protein, and lysozyme were also followed and correlated well (r = .78 and .92) with the amount of Mol antigen present on the cell surface. Cytochrome b was also found to be higher (1.4-fold) on plasma membranes isolated from cytoplasts than on plasma membranes isolated from intact control cells. These results indicate that some fusion of granule membranes and plasma membranes occurred during treatment of PMNs with Ficoll plus cytochalasin b and during cytoplast preparation.  相似文献   
13.
Embury  SH; Gholson  MA; Gillette  P; Rieder  RF 《Blood》1985,65(3):769-771
We have identified a black individual with homozygous sickle cell anemia who is the silent carrier of alpha-thalassemia (genotype - alpha/alpha alpha) due to heterozygosity for the leftward deletion alpha-thal-2 haplotype. This deletion has not been described previously in a black subject and is the only leftward deletion that we have found among 255 alpha-thal-2 chromosomes from sickle cell subjects. Its effects on the clinical, hematologic, biosynthetic, and cellular pathology of sickle cell anemia resemble those reported for the common alpha-thalassemia genotypes of the black population.  相似文献   
14.
15.
16.
Blood donations in the United States have been screened for antibody to human T-lymphotropic virus type I (HTLV-I) by HTLV-I enzyme immunoassay (EIA) since November 1988. Specimens repeatedly found to be reactive by EIA undergo confirmation by supplementary serologic tests. We assessed the accuracy of blood center testing of 994 HTLV-I EIA repeat-reactive specimens in five US blood centers between November 1988 and December 1991. Of 410 confirmed HTLV-I/II donations, 407 (99.3%) were infected with HTLV-I/II, as determined by polymerase chain reaction (PCR) (403 cases) and by repeat serologic testing (4 cases). The three false- positive results occurred in the first year of testing. Of 425 HTLV- indeterminate specimens, 6 (1.4%) were found to be infected by PCR (5 with HTLV-II and 1 with HTLV-I). None of 159 confirmatory test-negative donations was PCR positive. Of HTLV-I/II-seropositive specimens, 80.2% to 95.4% could be typed as HTLV-I or HTLV-II by type-specific serologic assays. These results support recommendations that HTLV-I/II- seropositive donors should be advised that they are infected with HTLV- I, HTLV-II, or HTLV-I/II (depending on results of type-specific assays). HTLV-indeterminate donors should be advised that their results only rarely indicate HTLV infection. HTLV confirmatory test-negative donors should be reassured that they are not infected with HTLV-I or HTLV-II.  相似文献   
17.
18.

Introduction

Soft tissue reactions following metal-on-metal (MoM) arthroplasty of the hip have been under considerable discussion. These reactions are seen following both hip resurfacing and MoM total hip arthroplasty (THA). The phenomenon may arise owing to shedding of metal particles in high wear states, hypersensitivity with normal metal wear rates or a combination of the two.

Methods

Three patients were identified who had developed a soft tissue reaction (pseudotumour) following MoM hip resurfacing procedures. The prostheses were revised to ceramic-on-ceramic (CoC) THA with only minimal debridement of the pseudotumour. Pre and postoperative magnetic resonance imaging was performed to assess the size of the lesions.

Results

Progressive and satisfactory resolution of the associated pseudotumours was identified following revision of the prostheses to CoC THA.

Conclusions

In the early stages of pseudotumour formation following MoM hip resurfacing, this potentially devastating condition can be managed adequately with revision to a CoC bearing THA with minimal soft tissue excision.  相似文献   
19.
ABSTRACT: BACKGROUND: A thorough understanding of the literature generated from research in care homes is required to support evidence-based commissioning and delivery of healthcare. So far this research has not been compiled or described. We set out to describe the extent of the evidence base derived from randomized controlled trials conducted in care homes. METHODS: A systematic mapping review was conducted of the randomized controlled trials (RCTs) conducted in care homes. Medline was searched for "Nursing Home", "Residential Facilities" and "Homes for the Aged"; CINAHL for "nursing homes", "residential facilities" and "skilled nursing facilities"; AMED for "Nursing homes", "Long term care", "Residential facilities" and "Randomized controlled trial"; and BNI for "Nursing Homes", "Residential Care" and "Long-term care". Articles were classified against a keywording strategy describing: year and country of publication; randomization, stratification and blinding methodology; target of intervention; intervention and control treatments; number of subjects and/or clusters; outcome measures; and results. RESULTS: 3226 abstracts were identified and 291 articles reviewed in full. Most were recent (median age 6 years) and from the United States. A wide range of targets and interventions were identified. Studies were mostly functional (44 behaviour, 20 prescribing and 20 malnutrition studies) rather than disease-based. Over a quarter focussed on mental health. CONCLUSIONS: This study is the first to collate data from all RCTs conducted in care homes and represents an important resource for those providing and commissioning healthcare for this sector. The evidence-base is rapidly developing. Several areas - influenza, falls, mobility, fractures, osteoporosis - are appropriate for systematic review. For other topics, researchers need to focus on outcome measures that can be compared and collated.  相似文献   
20.
As treatments of the extra-cardiac complications of muscular dystrophy (MD) improve, males with MD are more likely to develop cardiac disease. The impact of cardiomyopathy or heart failure (HF) and ventricular tachycardia (VT) on hospitalizations and in hospital mortality are not known. We performed an analysis of inpatient admission data for patients with MD using the Pediatric Health Information System database. We selected males who were 6 years or older with diagnosis codes of MD and cardiac disease including cardiomyopathy/HF and VT between 2003 and 2013. We created a logistic regression model to identify predictors of subsequent cardiac arrest or death in MD patients. We also compared hospital charges, lengths of stay and ages among MD patients with or without cardiac disease. Our logistic regression model showed that VT (OR 5.41, 95 % CI 2.83, 10.34) and cardiomyopathy/HF (OR 1.79, 95 % CI 1.05, 3.04) were risk factors for cardiac arrest or death. Of the 84 cardiac arrests or deaths in 3363 MD patients, 49 (58 %) were related to cardiac disease. Nineteen (39 %) of these events occurred in MD patients with VT. The mean hospital charges and the mean length of stay were greater and longer in MD patients with VT compared to those without cardiac disease and those with only cardiomyopathy/HF (p < 0.05). Cardiac disease is a significant burden in hospitalized MD patients. Our results suggest that VT and cardiomyopathy/HF are associated with an increased risk of cardiac arrest or death in MD patients.  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