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   380篇
  免费   32篇
耳鼻咽喉   5篇
儿科学   6篇
妇产科学   1篇
基础医学   68篇
口腔科学   4篇
临床医学   41篇
内科学   55篇
皮肤病学   5篇
神经病学   56篇
特种医学   22篇
外科学   73篇
预防医学   14篇
眼科学   1篇
药学   39篇
肿瘤学   22篇
  2023年   8篇
  2022年   9篇
  2021年   15篇
  2020年   16篇
  2019年   12篇
  2018年   17篇
  2017年   9篇
  2016年   14篇
  2015年   14篇
  2014年   16篇
  2013年   31篇
  2012年   39篇
  2011年   30篇
  2010年   8篇
  2009年   15篇
  2008年   20篇
  2007年   19篇
  2006年   16篇
  2005年   11篇
  2004年   11篇
  2003年   4篇
  2002年   12篇
  2001年   6篇
  2000年   17篇
  1999年   6篇
  1998年   5篇
  1997年   1篇
  1996年   1篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1989年   2篇
  1987年   3篇
  1985年   1篇
  1984年   1篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1974年   1篇
  1971年   2篇
  1970年   1篇
  1967年   2篇
  1964年   2篇
  1963年   1篇
  1942年   1篇
  1929年   1篇
排序方式: 共有412条查询结果,搜索用时 0 毫秒
11.
Progression of kidney damage was studied in 18 patients with Balkan endemic nephropathy (BEN), with a mean 15-year follow-up after renal biopsy. According to kidney function, estimated by 99mTc-DTPA clearance, patients were divided into three groups: with apparently normal kidney function (clearance 103.5 ± 21.3 mL/min/1.73 m2), with incipient renal failure (clearance 65.5 ± 11.3), and with advanced renal failure (clearance 28.0 ± 6.2). The mean yearly decrease of glomerular filtration rate was 2.74 mL/min. In two patients, an increase of kidney function was recorded. Six patients become dialysis dependent, two from the group with incipient renal failure, but all four from the group with advanced renal failure. Three patients died after 8 to 12 years of follow-up, one from causes unrelated to kidney disease and two from end-stage renal failure. This study has shown that BEN is characterized by a slow course and prolonged evolution, modified by medical supervision and treatment.  相似文献   
12.
The increasing importance of preventive measures in the field of orthopedics and trauma surgery becomes apparent because of the demographic changes and the high risk for secondary fractures following osteoporotic fractures. Within the fracture treatment chain, orthopedics and trauma surgery are in the “pole position” to initiate these measures in geriatric patients. In the past orthopedists and trauma surgeons have constantly accused of neglecting secondary fracture prevention in fragility fracture patients. There are several reasons that speak in favor of us undertaking a role in secondary fracture prevention: osteoporosis medication is highly effective in fracture prevention when correctly indicated, the positive effects of osteoporosis therapy on fracture healing and legal issues. Arguments that have been used to justify neglect of secondary fracture prevention are undesired side effects related to osteoporosis medications, such as atypical femoral fractures and osteonecrosis of the jaws, interference of some specific drugs with fracture healing and the working conditions in emergency departments. These run contrary to the consideration of chronic diseases such as osteoporosis, secondary osteoporosis and the underlying disease could be overlooked and the increasing complexity of medicinal osteoporosis therapy.  相似文献   
13.
14.
Background

Vaccination prevents severe morbidity and mortality from COVID-19 in the general population. The immunogenicity and efficacy of SARS-CoV-2 vaccines in patients with antibody deficiency is poorly understood.

Objectives

COVID-19 in patients with antibody deficiency (COV-AD) is a multi-site UK study that aims to determine the immune response to SARS-CoV-2 infection and vaccination in patients with primary or secondary antibody deficiency, a population that suffers from severe and recurrent infection and does not respond well to vaccination.

Methods

Individuals on immunoglobulin replacement therapy or with an IgG less than 4 g/L receiving antibiotic prophylaxis were recruited from April 2021. Serological and cellular responses were determined using ELISA, live-virus neutralisation and interferon gamma release assays. SARS-CoV-2 infection and clearance were determined by PCR from serial nasopharyngeal swabs.

Results

A total of 5.6% (n?=?320) of the cohort reported prior SARS-CoV-2 infection, but only 0.3% remained PCR positive on study entry. Seropositivity, following two doses of SARS-CoV-2 vaccination, was 54.8% (n?=?168) compared with 100% of healthy controls (n?=?205). The magnitude of the antibody response and its neutralising capacity were both significantly reduced compared to controls. Participants vaccinated with the Pfizer/BioNTech vaccine were more likely to be seropositive (65.7% vs. 48.0%, p?=?0.03) and have higher antibody levels compared with the AstraZeneca vaccine (IgGAM ratio 3.73 vs. 2.39, p?=?0.0003). T cell responses post vaccination was demonstrable in 46.2% of participants and were associated with better antibody responses but there was no difference between the two vaccines. Eleven vaccine-breakthrough infections have occurred to date, 10 of them in recipients of the AstraZeneca vaccine.

Conclusion

SARS-CoV-2 vaccines demonstrate reduced immunogenicity in patients with antibody deficiency with evidence of vaccine breakthrough infection.

  相似文献   
15.

Purpose  

Although grafts can be made from the same materials, the final weave of the product may play a role in the ultimate outcomes or complications. The aim of this experimental study is to evaluate and compare the mechanical properties of the meshes and their influence on biological characteristics as well.  相似文献   
16.
Fetal growth is considered a multifactorially-influenced characteristic. Genetic factors were found to play the main role in fetal growth determination, and it is the polygenic inheritance. The paper reviews the birthweights of 360 unlike-sexed two-egg twins, born at the Clinic of Gynecology and Obstetrics, Faculty of Medicine in Beograd, from January 1, 1970 through June 30, 1984. The mean birthweight differences between the male (2954.94 +/- 704.28 g) and female (2313.19 +/- 651.32 g) fetuses, amounted to 141.75 g. The difference is highly significant (P less than 0.01); variation coefficient shows that the examined groups were homogenous (VC was below 30%). The results were discussed from the genetic point of view, and particularly from the point of view of sex constitution, with special respect to the effect of Y chromosome on fetal growth. It has been known that human somatic development, body weight, bone maturation and teeth development are influenced by variety of factors. In addition to nutritional and other factors of the external environment, genetic and humoral factors are leading. The fact that fetuses with XY male constitution are heavier at birth than female fetuses with XX constitution, made us consider the correlation between genotype-phenotype, and the mentioned characteristics. This study was aimed at finding out the role of genetic factors in fetal growth, with respect to sex constitution, particularly to chromosome effect on fetal growth in unlike-sexed two-egg twins.  相似文献   
17.
18.
Polyamines were found to modulate the activity of several membrane-bound enzymes, participating in cell growth and differentiation. We have studied the effect of polyamines (spermidine, spermine and putrescine) on rat mesangial cell ectoenzymes: 5'-nucleotidase, Mg(2+)-ATPase and Ca(2+)-ATPase. Ecto-5'-nucleotidase activity was significantly increased after 48 h treatment with spermine and spermidine. Mg(2+)-ATPase was increased only after treatment with spermidine; however, Ca(2+)-ATPase was significantly increased after both spermine and spermidine treatment of mesangial cells. Culture of mesangial cells with putrescine did not change the activity of these ectoenzymes. Increased expression of mesangial cell ecto-ATPase and ecto-5'-nucleotidase after spermine and spermidine treatment could result in an increased production of adenosine, a powerful autacoid interesting with respect to a role of mesangial cells in inflammatory processes.  相似文献   
19.
Whether different odorous compounds (odorants) are processed by different cerebral circuits is presently unknown. A first step to address this complicated issue is to investigate how the cerebral regions mediating signals from olfactory (i.e., unimodal) odorants, differ from those mediating the olfactory + trigeminal (i.e., bimodal) odorants. [15O]-H2O-PET scans were conducted in 12 healthy females during three separate conditions: birhinal, passive smelling of: 1) the unimodal odorant vanillin; 2) the bimodal odorant acetone; and 3) odorless air. Significant activations were calculated contrasting vanillin to air, acetone to air, and deactivations, running these contrasts in the opposite direction. Smelling of vanillin activated bilaterally the amygdala and piriform cortex. These regions were only engaged slightly by acetone. Instead, strong activations were found in the anterior and central insula and claustrum, the posterior portion of anterior cingulate, the somatosensory cortex (SI for face), cerebellum, ventral medial (VMPo) and dorsal medial (MDvc) thalamus, the lateral hypothalamus, and pons/medulla. In parallel, the somatosensory (SI, below central representation of face), secondary visual and auditory cortices, as well as the supplementary motor area and the parahippocampal gyri were deactivated. No deactivations were observed with vanillin, although the odor components of acetone and vanillin were rated similarly intense (75 +/- 17 mm vs. 61 +/- 22 mm, NS). The differentiated pattern of cerebral activation during odorant perception seems to be dependent on the signal transducing cranial nerves involved. In contrast to vanillin, which solely activates the olfactory cortex, acetone engages predominantly trigeminal projections from the nasal mucosa. Acetone's limited activation of the olfactory cortex may result from a cross-modal interaction, with inhibition of acetone's odor component by its trigeminal component.  相似文献   
20.
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