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   3370篇
  免费   266篇
  国内免费   77篇
耳鼻咽喉   3篇
儿科学   36篇
妇产科学   166篇
基础医学   328篇
口腔科学   12篇
临床医学   150篇
内科学   420篇
皮肤病学   36篇
神经病学   291篇
特种医学   57篇
外科学   1107篇
综合类   329篇
预防医学   181篇
眼科学   12篇
药学   372篇
中国医学   133篇
肿瘤学   80篇
  2024年   8篇
  2023年   23篇
  2022年   57篇
  2021年   71篇
  2020年   77篇
  2019年   81篇
  2018年   96篇
  2017年   95篇
  2016年   103篇
  2015年   106篇
  2014年   179篇
  2013年   259篇
  2012年   141篇
  2011年   154篇
  2010年   126篇
  2009年   144篇
  2008年   158篇
  2007年   145篇
  2006年   142篇
  2005年   119篇
  2004年   97篇
  2003年   92篇
  2002年   97篇
  2001年   68篇
  2000年   70篇
  1999年   69篇
  1998年   59篇
  1997年   47篇
  1996年   56篇
  1995年   43篇
  1994年   35篇
  1993年   50篇
  1992年   45篇
  1991年   27篇
  1990年   32篇
  1989年   39篇
  1988年   48篇
  1987年   35篇
  1986年   32篇
  1985年   34篇
  1984年   38篇
  1983年   40篇
  1982年   67篇
  1981年   35篇
  1980年   41篇
  1979年   39篇
  1978年   39篇
  1977年   19篇
  1976年   13篇
  1975年   14篇
排序方式: 共有3713条查询结果,搜索用时 15 毫秒
31.
Activity of oxidative enzymes in the epithelium lining the uterine cavity and in the glandular epithelium of ovariectomized rats in the period of climacteric disorders was investigated by a comparative microphotometric method. An increase in lactate dehydrogenase (LD) and glucose-6-phosphate dehydrogenase (G6PD) activity and a decrease in succinate dehydrogenase (SD) and NAD- and NADP-diaphorase activity were found in the epithelial cells lining the uterine cavity. LD activity was increased in the glandular epithelium but SD, and NAD- and NADP-diaphorase activity was sharply reduced. Injection of testosterone propionate caused a marked increase in the activity of the oxidative enzymes studied in the endometrial epithelium of the rats compared with their activity in control rats and in rats not receiving the hormone.Research Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. Department of Obstetrics and Gynecology, Daghestan Medical Institute, Makhachkala. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 209–212, February, 1978.  相似文献   
32.
The androgens testosterone and dihydrotestosterone (DHT) are essential for a variety of systemic functions in mature males. Alteration of these hormones results in late-onset hypogonadism (LOH) and benign prostate hyperplasia (BPH). The fruit bodies of fungi of the genus Cordyceps have been regarded as folk medicine or health food with tonic and antifatigue effects. The extract from the fruit body of Cordyceps militaris parasitizing Samia cynthia ricini (CM) was evaluated as a novel-candidate natural product for ameliorating male andropause symptoms. To explore the effects of CM on LOH and BPH, CM was applied to rat models and cultured testicular cells and prostate cells. The concentrations of androgens in the serum and culture media were determined by ELISA. Expression of steroidogenic enzymes and androgen-related genes was evaluated by qPCR, and prostatic cell proliferation was assessed with the cell-viability assay. CM maintained the serum levels of testosterone and DHT, but inhibited testosterone-induced prostate hypertrophy. CM also increased the secretion of testosterone and DHT by primary testicular cells, with no changes in the mRNA expression of steroidogenic enzymes, but decreased the growth of prostatic cell lines. Our data suggest that CM could improve both LOH and BPH in males.  相似文献   
33.
The study was designed and conducted to evaluate the plant-based diet status and its association with erectile function (EF) in Chinese young healthy men. From July 2018 to May 2020, 116 objectively proved physically and psychologically healthy men were selected. Clinical questionnaires, detailed physical examinations and blood tests were all assessed. An overall plant-based diet index (PDI) and a healthful plant-based diet index (hPDI) were developed from each participant to measure plant-based diet quantitatively. The EF was measured by both the International Index of Erectile Function-5 (IIEF-5) and the surrogated measures of endothelial function, peripheral levels of nitric oxide (NO) and E-selectin. In subjects, the mean PDI and hPDI were 53.8 ± 8.2 and 54.7 ± 8.9 respectively. Results of multivariate analysis showed that both PDI and hPDI were negatively associated with BMI (all p < .05), but had no relationships with NO, E-selectin, TT levels and IIEF-5 scores (all p > .05). In a subgroup of male population, Chinese young healthy men, the plant-based diet, measured by PDI and hPDI, was not related to erectile function. The population can adhere to plant-based diet to keep healthy without concerns of negative influence on erectile function.  相似文献   
34.
BackgroundPrevious studies have suggested that the possible relationship between serum uric acid (SUA) and testosterone. However, the results of previous studies are controversial and there is limited evidence examining the relationship between SUA and testosterone in a general US population of men. The objective of this study is to explore the correlation of SUA and testosterone among adult males from the US.MethodsData from the National Health and Nutrition Examination Survey 2011–2016 were used, including a total of 7,796 male participants aged 18 years or older and excluding those lacking serum testosterone and uric acid data. Clinical characteristics of the participants among different SUA groups and testosterone groups are compared. Univariate and multivariate linear regression analyses were applied to evaluate the association between SUA and testosterone.ResultsWe found an inverse association between SUA and testosterone after fully adjusted the potential confounding factors in general US adult males. In the multivariate linear regression analysis, we found that increasing age (estimate testosterone percent difference: −0.20% per year, P<0.01), uric acid (estimate testosterone percent difference: −4.40% per md/dL, P<0.01) and BMI (estimate testosterone percent difference: −2.86% per kg/m2, P<0.01) were associated with declining serum testosterone. This association remained significant in sensitivity analysis, while in the stratified analysis, above association was not significant in men with diabetes or aged 65 and over.ConclusionsSUA levels might be negatively associated with serum testosterone in adult males.  相似文献   
35.
36.
Summary In this randomized, open-label trial, 24 subjects were studied. There were 12 subjects with essential hypertension and 12 normotensive controls who received, after an initial control period, 48 h of treatment with a transdermal estradiol patch or ketoconazole tablets every 8 h for six doses, or in combination. LHRH (100 g) and ACTH (250 g) were given at 48 h of each treatment. Each treatment was one week apart.In both normotensive and hypertensive men ketoconazole reduced adrenal and gonadal androgens, raised 11-deoxycortisol and 17 -hydroxyprogesterone levels; blunted the rise of cortisol to ACTH and had no effect on the response of LH to LHRH. Transdermal estradiol raised serum estradiol levels, blunted the time to peak plasma concentration of LH to LHRH and produced a normal response to ACTH. Although baseline level of total and free testosterone and DHEA-S were lower in hypertensive men, the response of the pituitary (LH) to LHRH and adrenal axis with ACTH were similar in both normotensive and hypertensive men. Blood pressure was unaffacted by any of the treatment interventions in either normotensive or hypertensive men.Although ketoconazole or transdermal estradiol reduce androgens, there was no evidence that this reduction in androgens was involved with the short term regulation of blood pressure in hypertensive men.  相似文献   
37.
目的 :为研究胃癌与激素之间的关系 ,本研究探讨了胃癌病人血清睾酮变化及其机理。方法 :应用放免法测定正常人、胃良性疾病和胃癌病人的血清睾酮、促间质细胞激素 (ICSH)。结果 :男性胃癌及胃良性疾病组血清睾酮、ICSH水平明显降低 ,但胃癌病人伴有出血和梗阻者血清睾酮、ICSH水平较同样胃良性疾病组病人降低更为明显。胃癌病人有出血和梗阻者血清睾酮、ICSH水平较不伴有并发症者降低更为明显。 期胃癌病人血清睾酮、ICSH水平与正常对照组对比显著降低。胃癌及胃良性疾病组血清睾酮、ISCH变化有显著相关性。结论 :1血清睾酮、ICSH水平可作为胃癌诊断的一个参考指标。 2胃癌及良性疾病血清睾酮、ICSH水平明显降低是由性腺轴抑制所引起。  相似文献   
38.
目的 研究贵州产名酒董酒、珍酒的保健作用。方法 采用氢化可的松 (以下简称氢可 )肌注 (每日 1次 ,连续 3d)复制小鼠阳虚症模型 ,用放免法测血清睾酮、皮质醇水平及心、肝、肾、睾丸组织形态学的变化 ,并比较董酒、珍酒对其的影响。结果 肌注氢可的各组血清皮质醇浓度明显增加 ,与正常组比较 ,差异具显著性 (P <0 .0 5 ) ;单纯阳虚组血清睾酮浓度虽不降低 ,但睾丸组织中生精状况差 ;而在阳虚 饮酒组 (董酒或珍酒组 ) ,血清睾酮浓度明显降低 (P <0 .0 5或P <0 .0 1) ,但睾丸组织中生精活跃 ,可见较多的精母细胞、精子细胞等精子发育良好。结论 董酒、珍酒可降低阳虚小鼠血清睾酮水平 ,但对其睾丸生精功能似有一定促进作用 ,其机制有待阐明。  相似文献   
39.
Aim: To demonstrate the role of the 8 kDa peptide in regulation of testosterone production by mt Leydig cells. Meth-ods: A peptide similar to 8 kDa peptide purified from immature rat Leydig cells was isolated and purified from rat lungcytosol. Immunological and structural similarity between the peptides purified from lung and Leydig cells was estab-lished by Western blot and tryptic map comparison respectively. Results: Addition of the 8 kDa peptide 10, 50, 100;and 150 ug decreased the production of testosterone in Leydig cells dose-dependently. But the addition of the peptide150 ug along with hCG had no effect on hCG-stimulated increase in testosterone production. Conclusion: In vitro ad-dition of the peptide purified from lung cytosol to adult rat Leydig cells resulted in a concentration-dependent decrease inbasal testosterone production although it had no effect on hCG-stimulated testosterone production. (Asian J Androl1999 Dec; 1: 191-194)  相似文献   
40.
Bone Mineral Density and Androgen Levels in Elderly Males   总被引:4,自引:0,他引:4  
To clarify the relationship of sex male hormones and bone in men, we studied in 140 healthy elderly men (aged 55–90 years) the relation between serum levels of androgens and related sex hormones, bone mineral density (BMD) at different sites, and other parameters related to bone metabolism. Our results show a slight decrease of serum-free testosterone with age, with an increase of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in a third of the elderly subjects studied. BMD decreased significantly with age in all regions studied, except in the lumbar spine. We found a positive correlation between body mass index (BMI) and BMD at the lumbar spine and femoral neck (P < 0.001). No relationship was found (uni- and multivariate regression analysis) between serum androgens or sex hormone-binding globulin (SHBG) and BMD. We found a positive correlation of vitamin D binding protein (DBP) and osteocalcin with lumbar spine BMD and with BMI, DBP, IGF-1, and PTH with femoral neck BMD. In conclusion, there is a slight decline in free testosterone and BMD in the healthy elderly males. However, sex male hormones are not correlated to the decrease in hip BMD. Other age-related factors must be associated with bone loss in elderly males. Received: 29 April 1997 / Accepted: 9 November 1997  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