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   973篇
  免费   168篇
  国内免费   17篇
耳鼻咽喉   12篇
儿科学   51篇
妇产科学   14篇
基础医学   49篇
口腔科学   14篇
临床医学   157篇
内科学   249篇
皮肤病学   29篇
神经病学   54篇
特种医学   77篇
外科学   206篇
综合类   48篇
现状与发展   20篇
预防医学   62篇
眼科学   27篇
药学   28篇
中国医学   2篇
肿瘤学   59篇
  2024年   6篇
  2023年   44篇
  2021年   23篇
  2020年   24篇
  2019年   12篇
  2018年   52篇
  2017年   47篇
  2016年   34篇
  2015年   46篇
  2014年   44篇
  2013年   57篇
  2012年   27篇
  2011年   41篇
  2010年   51篇
  2009年   64篇
  2008年   37篇
  2007年   27篇
  2006年   33篇
  2005年   18篇
  2004年   18篇
  2003年   16篇
  2002年   16篇
  2001年   17篇
  2000年   15篇
  1999年   21篇
  1998年   30篇
  1997年   32篇
  1996年   44篇
  1995年   31篇
  1994年   17篇
  1993年   22篇
  1992年   8篇
  1991年   10篇
  1990年   11篇
  1989年   12篇
  1988年   18篇
  1987年   14篇
  1986年   11篇
  1985年   12篇
  1984年   4篇
  1983年   7篇
  1982年   11篇
  1981年   4篇
  1980年   5篇
  1978年   12篇
  1977年   8篇
  1976年   7篇
  1975年   5篇
  1964年   5篇
  1963年   4篇
排序方式: 共有1158条查询结果,搜索用时 140 毫秒
991.
992.
993.
Previous reports have established that the telomeric copy of the survival motor neuron (SMNT) gene and the intact copy of the neuronal apoptosis inhibitory protein (NAIP) gene are preferentially deleted in patients with spinal muscular atrophy (SMA). Although deletions or mutations in the SMNT gene are most highly correlated with SMA, it is not clear to what extent NAIP or other genes influence the SMA phenotype, or whether a small fraction of SMA patients actually have functional copies of both SMNT and NAIP. To evaluate further the part of SMNT in the development of SMA, we analyzed 280 asymptomatic SMA family members for the presence or absence of SMNT exons 7 and 8. We report the following observations: (i) 4% of the sample harbored a polymorphic variant of SMNT exon 7 that looks like a homozygous deletion; (ii) approximately 1% of the parents are homozygously deleted for both exons 7 and 8; (iii) one asymptomatic parent lacking both copies of SMNT exons 7 and 8 displays a 'subclinical phenotype' characterized by mild neurogenic pathology; (iv) another asymptomatic parent lacking both SMNT exons showed no signs of motor neuron disorder by clinical and neurodiagnostic analyses. The demonstration of polymorphic variants of exon 7 that masquerade as homozygous nulls, and the identification of SMA parents who harbor two disease alleles, serve as a caution to those conducting prenatal tests with these markers.   相似文献   
994.
995.
Background  Kaposi sarcoma (KS), a malignancy of dermal endothelial cells that is caused by human herpesvirus 8 (HHV8) infection, is sensitive to perturbations of immunity. Nicotine might be effective against KS because of its immunologic and vascular effects and because smoking is associated with a low risk of KS.
Objective and study design  We conducted a masked, randomized phase 2 clinical trial of transdermal nicotine and placebo patches to assess the safety and efficacy of nicotine against classic KS (cKS).
Subjects and methods  Three cKS lesions, predominantly nodules, in each of 24 non-smoking patients were randomly assigned to 15 weeks continuous treatment with nicotine patch (escalated to 7 mg), identical masked placebo patch or no patch. Changes in lesion area and elevation from baseline through six follow-up visits, by direct measurement and by two independent readers using digital photographs of the lesions, were compared using non-parametric and regression methods. Changes in longitudinal levels of HHV8 antibodies and DNA in blood cells were similarly assessed.
Results  There were no systemic or serious adverse events, and compliance was good. One patient resumed smoking and discontinued patches, and two patients withdrew at week 12 for unrelated indications. Six (29%) of the remaining 21 suspended use of patches to relieve local skin irritation; four of these six completed the trial at reduced dose. Treatment assignment was not associated with significant or consistent changes in cKS lesion area or elevation, HHV8 viral load or antibodies.
Conclusion  Transdermal nicotine and placebo patches caused no serious toxicities but had no demonstrable effect on nodular cKS lesions or HHV8 levels.  相似文献   
996.
997.
Human urethral glands were reacted histochemically and immunohistochemically to identify glycoproteins, some androgen metabolic enzymes, and VIP-like immunoreactivity. Neutral/acid mucosubstances were detected mainly in the apical cytoplasm of the principal cells. 3 beta-, 17 beta-, and 3 alpha-hydroxysteroid dehydrogenase, G6PD, and 6PGD reactivity were intense in all the glandular epithelium. Small amounts of VIP-positive fibers were noted around the secretory elements.  相似文献   
998.
Purpose: Although it is generally thought that lymphatics do not exist in the choroid, there is mounting evidence that lymphatic-like structures do exist in primates and fowl. Methods/Results: Our comparison of the ultrastructure of chick and rabbit outer choroid indicates that major differences exist in the non-vascular areas of the choroid: notably, the chick has large lymphatic sinusoids, whereas the rabbit only has a system of large vacuoles contained within the processes of individual fibroblasts. Conclusions: These results raise questions regarding the similarities or otherwise between species of the management of retinal metabolites, excess tissue fluid and choroidal homeostasis, especially during conditions of overload.  相似文献   
999.
SUMMARY Flecainide acetate is a potent class 1C antiarrhythmic agent, overdosage with which is rare. An overdose is reported in a patient on long-term therapy, resulting in life-threatening arrhythmias and prolonged electrocardiographic abnormalities.  相似文献   
1000.
Quality indicators in clinical nursing: a review of the literature   总被引:5,自引:0,他引:5  
The purpose of the present study was, by means of a literature review, to describe and analyse the characteristics of clinical indicators used to assess and promote quality improvement in nursing care.
It was found that a generally accepted definition of a clinical indicator is a 'quantitative measure that can be used as a guide to monitor and evaluate the quality of important patient care and support service activities'. By the seriousness of the event and the degree to which it can be avoided, clinical indicators are described as sentinel event or rate-based indicators. They can measure structure, process or outcome of care. Authors have had different approaches in focus when selecting and developing indicators viz. specific aspects of care/nursing diagnosis, medical diagnosis, generic aspects of care and clinical areas. These different points of departure were influenced by research knowledge, theories/frameworks, or by the opinions of patients or staff.
The threshold of an indicator is essential when measuring the quality of care as it describes a critical level between what is considered good or not.
Thresholds should be dynamic, realistic, and improve over time. However, the literature on how to establish specific thresholds is limited.
The review has also revealed that there is an uncertainty regarding the use of terms such as indicators, standards, norm, criteria and aspects of care.  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