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   1143篇
  免费   29篇
  国内免费   7篇
耳鼻咽喉   64篇
儿科学   64篇
妇产科学   55篇
基础医学   124篇
口腔科学   14篇
临床医学   67篇
内科学   231篇
皮肤病学   18篇
神经病学   146篇
特种医学   10篇
外科学   54篇
综合类   6篇
预防医学   77篇
眼科学   47篇
药学   137篇
中国医学   3篇
肿瘤学   62篇
  2023年   2篇
  2022年   4篇
  2021年   16篇
  2020年   6篇
  2019年   11篇
  2018年   12篇
  2017年   8篇
  2016年   17篇
  2015年   26篇
  2014年   21篇
  2013年   32篇
  2012年   69篇
  2011年   78篇
  2010年   29篇
  2009年   31篇
  2008年   83篇
  2007年   109篇
  2006年   136篇
  2005年   125篇
  2004年   106篇
  2003年   92篇
  2002年   113篇
  2001年   4篇
  2000年   1篇
  1999年   3篇
  1998年   7篇
  1997年   5篇
  1996年   4篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1992年   2篇
  1991年   5篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
排序方式: 共有1179条查询结果,搜索用时 15 毫秒
31.
Mitochondrial defects have been shown to be associated with the pathogenesis of Parkinson’s disease (PD). Yet, experience in PD research linking mitochondrial dysfunction, e.g., deregulation of oxidative phosphorylation, with neuronal degeneration and behavioral changes is rather limited. Using the 6-hydroxydopamine (6-OHDA) rat model of PD, we have investigated the potential role of mitochondria in dopaminergic neuronal cell death in the substantia nigra pars compacta by high-resolution respirometry. Mitochondrial function was correlated with the time course of disease-related motor behavior asymmetry and dopaminergic neuronal cell loss, respectively. Unilateral 6-OHDA injections (>2.5 μg/2 μl) into the median forebrain bundle induced an impairment of oxidative phosphorylation due to a decrease in complex I activity. This was indicated by increased flux control coefficient. During the period of days 2–21, a progressive decrease in respiratory control ratio of up to ?58 % was observed in the lesioned compared to the non-lesioned substantia nigra of the same animals. This decrease was associated with a marked uncoupling of oxidative phosphorylation. Mitochondrial dysfunction, motor behavior asymmetry, and dopaminergic neuronal cell loss correlated with dosage (1.25–5 μg/2 μl). We conclude that high-resolution respirometry may allow the detection of distinct mitochondrial dysfunction as a suitable surrogate marker for the preclinical assessment of potential neuroprotective strategies in the 6-OHDA model of PD.  相似文献   
32.
33.
Objectives: The 2nd to 4th digit ratio (2D:4D) is thought to reflect exposure to androgens during foetal development. This study examined the relationship between low (more masculine) and high (more feminine) 2D:4D and body size at different stages of the life course, adult testosterone levels and number of children among males.

Methods: Five hundred and fifty-eight men from rural Poland at the Mogielica Human Ecology Study Site participated in this study. Life history data and anthropometric measurements were collected. Salivary morning and evening testosterone levels among 110 men from the same population were measured.

Results: Low 2D:4D was related to higher birth weight (p?=?0.04), higher birth length (p?=?0.01), higher body mass during childhood and adolescence (p?=?0.01), higher BMI (borderline significance, p?=?0.06), higher number of children among fathers (p?=?0.04) and higher testosterone levels during adulthood (p?=?0.04).

Conclusions: This study shows, for the first time in a single population, that digit ratio is related to sub-adult body size at different stages of the life course, adult testosterone levels and number of children. The observed results suggest that digit ratio might be a valuable predictor of male body size and reproductive characteristics.  相似文献   
34.
INTRODUCTION: The body mass gain is conditioned by lifestyle, as well as many environmental and genetic factors. Recent studies suggest that renin-angiotensin system (RAS) plays a fundamental role in process of growth and differentiation of adipocytes through the acting of angiotensin II and seems to be a significant factor in excessive weight gain development. The purpose of this study was to determine the frequency and significance of insertion/deletion polymorphism (I/D) of the ACE gene in pregnant women with excessive weight gain. MATERIALS AND METHODS: The examined group consisted of 212 pregnant women, including 107 women with normal (DeltaBMI< or =5) and 105 women with excessive weight gain (DeltaBMI>5). Genomic DNA was extracted from venous blood. The I/D polymorphism of ACE gene was determined by polymerase chain reaction (PCR). RESULTS: During the course of the study we did not observe the statistically significant higher frequency of ACE genotypes in any of the two investigated groups of women with normal and excessive weight gain. Nevertheless, an overrepresentation of II genotype frequency in group with excessive weight gain has been observed (33.3 vs 21.5%, p=ns). The same findings were visible as far as the frequency of I allele in group with excessive weight gain was concerned (55.2 vs 45.8%, p=ns). The frequency of observed genotypes was in agreement with Hardy-Weinberg equilibrium. CONCLUSIONS: Although overrepresentation of II genotype and I allele in the group of pregnant women with excessive weight gain (DeltaBMI>5) has been observed, a close correlation between II genotype and higher risk of overweight could be not indicated (due to the lack of significant difference). The results should be confirmed in a more numerous group of pregnant women. At this stage the results of the study did not suggested the presence of association of I/D polymorphism of ACE gene with weight gain in investigated group of pregnant women.  相似文献   
35.
Naloxone benzoylhydrazone (NalBzoH) has proved a valuable tool in the investigation of opioid receptor subtypes. In the present study, we have examined a series of derivatives of NalBzoH in which substitutions have been made on the benzoyl ring. Overall, we see dramatic effects on the binding affinities of derivatives against the various opioid receptor subtypes. Although the range of affinities against the mu receptors is quite modest, ranges of the others vary almost 30-fold for kappa3, 50-fold for kappa1 and 100-fold for delta and kappa2 binding. Few substituted derivatives display greater affinity than NalBzoH for any of the receptors, except for delta sites where several derivatives have affinities almost tenfold greater than NalBzoH. Along with the wide variations in affinity, the compounds also appear to exhibit widely divergent activities in traditional biosasays. © 1996 Wiley-Liss, Inc.  相似文献   
36.
目的 以往关于心力衰竭患者自我照顾的研究强调了其重要性,特别对移民患者而言.护士在为慢性病(如心力衰竭)患者提供相关信息并促进他们积极进行自我照顾方面发挥着重要作用.本研究旨在加强研究者及护士的认识,为患有心力衰竭的移民的自我照顾提供最佳支持.方法 采用质性研究方法.2020年10-12月,对瑞典西部不同类型机构心力衰...  相似文献   
37.
Senescence of vascular smooth muscle cells (VSMCs) contributes to aging as well as age-related diseases of the cardiovascular system. Senescent VSMCs have been shown to be present in atherosclerotic plaques. Both replicative (RS) and stress-induced premature senescence (SIPS) accompany cardiovascular diseases. We aimed to establish the signature of RS and SIPS of VSMCs, induced by a common anticancer drug, doxorubicin, and to discover the so far undisclosed features of senescent cells that are potentially harmful to the organism. Most of the senescence hallmarks were common for both RS and SIPS; however, some differences were observed. 32 % of doxorubicin-treated cells were arrested in the G2/M phase of the cell cycle, while 73 % of replicatively senescing cells were arrested in the G1 phase. Moreover, on the basis of alkaline phosphatase activity measurements, we show that a 7-day treatment with doxorubicin (dox), does not cause precocious cell calcification, which is a characteristic feature of RS. We did not observe calcification even though after 7 days of dox-treatment many other markers characteristic for senescent cells were present. It can suggest that dox-induced SIPS does not accelerate the mineralization of vessels. We consider that detailed characterization of the two types of cellular senescence can be useful in in vitro studies of potential anti-aging factors.  相似文献   
38.
THE AIM: The aim of the study was a retrospective analysis of operative procedures, laparoscopy or laparotomy, carried out in cases of benign adolescent ovarian tumours. MATERIAL AND METHODS: A retrospective review of 709 patient charts with ovarian tumours, who had undergone surgical interventions at The Department of Surgical Gynaecology and Endoscopy of The Polish Mother's Memorial Hospital--Research Institute in ?ód?--has been conducted. Among groups of girls treated either with laparoscopy or laparotomy, the following parameters were analysed: age of the patients, character of the tumour (based on the pathological result), size of the lesion, type of the surgical procedure, duration of the hospitalisation and postoperative complications. RESULTS: 109 girls had ovarian tumours operated--54 times laparoscopy and 55 laparotomy times were performed. An average age of patients who underwent laparoscopy was 16.2 years, in case of laparotomy: 15.3 years (p > 0.05). An average size of tumours excised in laparotomy was 82 mm (60-190 mm), whereas in laparoscopy 64 mm (30-80 mm) (p > 0.05). The most common laparotomic procedure was the ovarian cystectomy (63%) and cystovariectomy (32%), while during laparoscopy the cystectomy was performed in 92% (p > 0.05). Duration of the laparoscopy was shorter, average was 46.7 min, whereas mean time of laparotomy was 49.2 min (p > 0.05). Also duration of postoperative hospitalisation was longer in case of laparotomy, its average time was 5.4 days in comparison with laparoscopy--2.8 days (p < 0.05). CONCLUSIONS: Laparoscopy performed in adolescents due to benign ovarian tumours seems to be a very safe way of the surgical treatment. Moreover, laparoscopy reduces duration of hospitalisation and convalescence, also giving a nice cosmetic effect.  相似文献   
39.
40.
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