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   414篇
  免费   18篇
  国内免费   4篇
耳鼻咽喉   5篇
儿科学   10篇
妇产科学   12篇
基础医学   40篇
口腔科学   9篇
临床医学   39篇
内科学   128篇
皮肤病学   1篇
神经病学   22篇
特种医学   15篇
外科学   90篇
预防医学   30篇
眼科学   4篇
药学   9篇
肿瘤学   22篇
  2023年   3篇
  2022年   6篇
  2021年   21篇
  2020年   8篇
  2019年   12篇
  2018年   11篇
  2017年   13篇
  2016年   7篇
  2015年   6篇
  2014年   11篇
  2013年   22篇
  2012年   32篇
  2011年   17篇
  2010年   10篇
  2009年   8篇
  2008年   12篇
  2007年   24篇
  2006年   19篇
  2005年   19篇
  2004年   18篇
  2003年   16篇
  2002年   16篇
  2001年   10篇
  2000年   11篇
  1999年   14篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1994年   5篇
  1992年   3篇
  1991年   12篇
  1990年   17篇
  1989年   8篇
  1988年   8篇
  1987年   10篇
  1986年   3篇
  1985年   3篇
  1984年   1篇
  1979年   2篇
  1973年   5篇
  1970年   1篇
  1968年   3篇
  1967年   2篇
  1966年   2篇
  1965年   1篇
排序方式: 共有436条查询结果,搜索用时 15 毫秒
71.
Chinchilloidea are a clade of caviomorph rodents that includes seven living species, the Dinomyidae Dinomys branickii, the Chinchillidae Lagostomus maximus, two species of Chinchilla and three species of Lagidium. In addition, two extinct families are traditionally considered chinchilloids – Neoepiblemidae and Cephalomyidae. The phylogeny of the Chinchilloidea has so far not been well established and is based on partial analyses. Studying the anatomy and ontogeny of extinct and extant taxa, we propose homologies for the upper molars of Chinchilloidea for which these homologies have not been previously proposed: that is the Chinchillidae Prolagostomus, Lagostomus, Lagidium and Chinchilla, and the Neoepiblemidae Neoepiblema and Phoberomys. We identify patterns of occlusal simplification within Chinchilloidea and evaluate its importance in an evolutionary context. A phylogenetic analysis recovered Dinomyidae, Chinchillidae and Neoepiblemidae as clades. ‘Cephalomyidae’ have not been not recovered as a monophyletic group and ‘cephalomyids’ are closely related to Neoepiblemidae. Branisamys is not included within the Dinomyidae and appears to be a basal chinchilloid.  相似文献   
72.
73.
Some renal transplant patients show cognitive, emotional, and behavioral changes as part of possible neurotoxic effects associated with immunosuppressive medication, especially tacrolimus. This study evaluated effects of immunosuppressive drugs on some cognitive tasks. Patients treated with sirolimus and cyclosporine reported some of the noncognitive side effects related to immunosuppressive treatment. We observed attention and working memory impairment in patients treated with sirolimus or tacrolimus. Performance of cyclosporine-treated subjects was similar to that of healthy volunteer controls. Since the mood, anxiety, and sleep patterns measured were unaffected, it could be concluded that the cognitive deficit found was partly related to treatment.  相似文献   
74.
75.
An emerging central concept in evolutionary biology suggests that symbiosis is a universal characteristic of living organisms that can help in understanding complex traits and phenotypes. During evolution, an integrative circuitry fundamental for survival has been established between commensal gut microbiota and host. On the basis of recent knowledge in worms, flies, and humans, an important role of the gut microbiota in aging and longevity is emerging. The complex bacterial community that populates the gut and that represents an evolutionary adapted ecosystem correlated with nutrition appears to limit the accumulation of pathobionts and infections in all taxa, being able of affecting the efficiency of the host immune system and exerting systemic metabolic effects. There is an urgent need to disentangle the underpinning molecular mechanisms, which could shed light on the basic mechanisms of aging in an ecological perspective. Thus, it appears possible to extend healthy aging and lifespan by targeting the host as a metaorganism by manipulating the complex symbiotic ecosystem of gut microbiota, as well as other possible ecosystems of the body.  相似文献   
76.

Purpose  

Cranial nerve microvascular decompression is a habitual neurosurgical procedure. Authors describe a new application of the Dextroscope? (Volume Interactions, Ltd.), a virtual reality environment, to plan and properly simulate this kind of procedures.  相似文献   
77.
78.
To determine if increased lead absorption was associated with sperm count suppression or perterbation of the hypothalamopituitary system, we compared battery workers (N=18), who were exposed to high airborne lead levels, with cement workers (N=18), who were exposed to ambient lead levels. Blood lead, urinary lead, semen lead, and zinc protoporphyrin concentrations were markedly elevated (p<.001) in battery workers. Battery workers had a significantly shifted (p<.025) frequency distribution of sperm count (median count, 45 vs. 73 × 106 cells/cc, respectively). There were no significant differences between the two groups in mean follicle-stimulating hormone, testosterone, prolactin, luteinizing hormone, or total neutral 17-ketosteroid levels. Potential confounding factors (alcohol, cigarette, and coffee consumption, frequency of intercourse, and days of abstinence prior to semen donation) were not significantly different between the two groups. These results suggest a direct toxic effect of increased lead absorption on sperm production or transport in man.  相似文献   
79.
Background and purpose — Long-term alcohol intake is associated with various negative effects on capillary microcirculation and tissue perfusion. We hypothesized that alcohol consumption might be a risk factor for both the occurrence and the severity of rotator cuff tears (RCTs).Patients and methods — A case-control study was performed. We studied 249 consecutive patients (139 men and 110 women; mean age 64 (54–78) years) who underwent arthroscopic rotator cuff repair. Tear size was determined intraoperatively. The control group had 356 subjects (186 men and 170 women; mean age 66 (58–82) years) with no RCT. All participants were questioned about their alcohol intake. Participants were divided into: (1) non-drinkers if they consumed less than 0.01 g of ethanol per day, and (2) moderate drinkers and (3) excessive drinkers if women (men) consumed > 24 g (36 g) per day for at least 2 years.Results — Total alcohol consumption, wine consumption, and duration of alcohol intake were higher in both men and women with RCT than in both men and women in the control group. Excessive alcohol consumption was found to be a risk factor for the occurrence of RCT in both sexes (men: OR = 1.7, 95% CI: 1.2–3.9; women: OR = 1.9, 95% CI: 0.94–4.1). Massive tears were associated with a higher intake of alcohol (especially wine) than smaller lesions.Interpretation — Long-term alcohol intake is a significant risk factor for the occurrence and severity of rotator cuff tear in both sexes.The supraspinatus and infraspinatus tendons have a hypovascularized portion approximately 15 mm in length at their insertion on the great tuberosity (Rothman et al. 1965, Blevins et al. 1997). Any systemic or local disease or life habit that can negatively influence the capillary microcirculation, such as arterial hypertension (Gumina et al. 2013), cardiopulmonary disease (Harryman et al. 2003), obesity (Gumina et al. 2014), smoking (Carbone et al. 2012), and hypercholesterolemia (Kim et al. 2000), can—from local hypoxia—lead to tendon degeneration and rupture (Benson et al. 2010).Many studies on humans and animals have shown that habitual high-dose intake of ethanol-containing beverages has various negative effects on capillary microcirculation and tissue perfusion (Liu et al. 2002, Fuchs 2005, Zilkens et al. 2005, Beilin and Puddey 2006, Costanzo et al. 2010, Wakabayashi 2011, Shirpoor et al. 2012).We therefore hypothesized that long-term intake of high doses of alcohol might be a risk factor for both the occurrence and the severity of rotator cuff tears (RCTs).  相似文献   
80.
Erratum     
Results — Total alcohol consumption, wine consumption, and duration of alcohol intake were higher in both men and women with RCT than in both men and women in the control group. Excessive alcohol consumption was found to be a risk factor for the occurrence of RCT in both sexes (men: OR =3.0, CI: 1.5–6.0, p < 0.001; women: OR =3.6, CI: 1.7–7.8, p < 0.001). Massive tears were associated with a higher intake of alcohol (especially wine) than smaller lesions.  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