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   1052篇
  免费   57篇
  国内免费   99篇
耳鼻咽喉   6篇
儿科学   42篇
妇产科学   21篇
基础医学   143篇
口腔科学   20篇
临床医学   147篇
内科学   312篇
皮肤病学   8篇
神经病学   25篇
特种医学   128篇
外科学   50篇
综合类   43篇
一般理论   10篇
预防医学   101篇
眼科学   5篇
药学   100篇
肿瘤学   47篇
  2023年   9篇
  2022年   6篇
  2021年   10篇
  2020年   7篇
  2019年   15篇
  2018年   17篇
  2017年   14篇
  2016年   15篇
  2015年   19篇
  2014年   31篇
  2013年   42篇
  2012年   47篇
  2011年   36篇
  2010年   48篇
  2009年   41篇
  2008年   49篇
  2007年   104篇
  2006年   44篇
  2005年   46篇
  2004年   23篇
  2003年   33篇
  2002年   24篇
  2001年   34篇
  2000年   19篇
  1999年   27篇
  1998年   43篇
  1997年   38篇
  1996年   34篇
  1995年   35篇
  1994年   29篇
  1993年   39篇
  1992年   18篇
  1991年   16篇
  1990年   23篇
  1989年   31篇
  1988年   27篇
  1987年   20篇
  1986年   20篇
  1985年   14篇
  1984年   10篇
  1983年   3篇
  1982年   7篇
  1981年   4篇
  1980年   10篇
  1979年   3篇
  1978年   4篇
  1977年   10篇
  1976年   2篇
  1973年   4篇
  1956年   2篇
排序方式: 共有1208条查询结果,搜索用时 15 毫秒
41.
A high prevalence of asthma and airway hyperresponsiveness (AHR) has been reported in the athlete population. Factors potentially predisposing athletes to these conditions have not been clearly identified. Although moderate exercise has been shown to be beneficial in patients with asthma, repeated high-intensity exercise could possibly contribute to the development of asthma and AHR. This report provides an overview of the prevalence and possible mechanisms of development of asthma and AHR in the athlete population. The prevalence of asthma and AHR are higher in athletes than in the general population, particularly in swimmers and athletes performing sports in cold air environments. Possible mechanisms involved in the development of asthma in athletes are still uncertain; however, the content and physical characteristics of the inhaled air seem to be important factors, while immune and neurohumoral influences could play a modulatory role. This report stresses the need for further studies to better define the aetiologic factors and mechanisms involved in the development of asthma and AHR in athletes, and proposes relevant preventive and therapeutic measures.  相似文献   
42.
43.
The renal insulin-like growth factor-I (IGF-I) system has been implicated in the pathogenesis of renal hypertrophy, altered hemodynamics, and extracellular matrix expansion associated with early diabetes. The relative abundance of IGF binding proteins (IGFBPs) in the renal microenvironment may modulate IGF-I actions. However, the precise IGFBPs expressed in the glomerular and tubulointerstitial compartments during diabetic renal growth have not been characterized. In the present study, in situ hybridization studies were performed to examine the expression of IGFBP-1 to -6 messenger RNAs (mRNAs) 3, 7, and 14 days after streptozotocin (STZ) injection in rats. In control, nondiabetic kidneys, all six IGFBP mRNAs were differentially expressed with a predominance of IGFBP-5. The onset of renal hypertrophy in STZ-induced diabetes was associated with a rapid and site-specific induction of IGFBP-1, -3, and -5 mRNAs. In contrast, basal expression of IGFBP-2, -4, and -6 mRNAs was not altered in diabetic rats. IGFBP-5 mRNA expression increased in diabetic glomeruli, cortical, and inner medullary peritubular interstitial cells at days 3, 7, and 14. Although normal glomeruli failed to express IGFBP-3, it was induced concomitantly with IGFBP-5 in diabetic glomeruli and cortical peritubular interstitial cells. IGFBP-1 mRNA levels also increased in cortical tubular cells at each time point tested. Peak induction of IGFBP-3 and -5 was observed at day 3, whereas IGFBP-1 was delayed until day 7. IGFBP-1, -3, and -5 mRNA levels declined by day 14, but remained persistently elevated above control. By immunoperoxidase staining, similar alterations in the pattern of IGFBP-3 and -5 protein expression were observed at each time point. The preferential and site-specific increase in IGFBP-1, -3, and -5 suggest that these IGFBPs may regulate the local autocrine and/or paracrine actions of IGF-I and contribute to the pathogenesis of the early manifestations of diabetic nephropathy.  相似文献   
44.
目的测定甘肃产五加中剌五加苷B、苷E的含量。方法高效液相色谱法,ODSKromasal柱。水乙晴(955)为流动相,检测波长222nm,柱温度25℃。结果本文可同时测定剌五加苷B、苷E的含量。剌五加苷B、苷E分别在0.064~0.320μg/ml;0.074~0.370μg/ml范围内峰面积与浓度呈线性关系,平均回收率分别为102.5%,RSD=4.2%,95.5%,RSD=4.6%。结论剌五加苷B、苷E在红毛五加中含量最高;茎皮中含量最高;剌五加苷E的含量高于苷B。  相似文献   
45.
High‐frequency stimulation (HFS) of the subthalamic nucleus (STN) is recognized as an effective treatment for the motor symptoms of Parkinson's disease (PD), but its mechanisms, particularly as concern dopaminergic transmission, remain unclear. The aim of this study was to evaluate changes in the expression of dopaminergic receptors (D1, D2, and D3 receptors) after prolonged (4 h) unilateral STN‐HFS in anesthetized intact rats and rats with total dopaminergic denervation. We used [3H]SCH 23390, [125I]iodosulpride, and [125I]OH‐PIPAT to assess the densities of D1R, D2R, and D3R, respectively, within different areas of the striatum—a major input structure of the basal ganglia—including the nucleus accumbens. We found that STN‐HFS increased D1R levels in almost all of the striatal areas examined, in both intact and denervated rats. By contrast, STN‐HFS led to a large decrease in D2R and D3R levels, limited to the nucleus accumbens and independent of the dopaminergic state of the animals. These data suggest that the influence of STN‐HFS on striatal D1R expression may contribute to its therapeutic effects on motor symptoms, whereas its impact on D2R/D3R levels in the nucleus accumbens may account for the neuropsychiatric side effects often observed in stimulated PD patients, such as postoperative apathy. © 2015 International Parkinson and Movement Disorder Society  相似文献   
46.
47.
Goldberg JF, McLeod LD, Fehnel SE, Williams VSL, Hamm LR, Gilchrist K. Development and psychometric evaluation of the Bipolar Functional Status Questionnaire (BFSQ). Bipolar Disord 2010: 12: 32–44. © 2010 The Authors.
Journal compilation © 2010 John Wiley & Sons A/S. Objectives: Persistently impaired psychosocial functioning has been recognized in many individuals with bipolar disorder. However, existing measures of functional disability have been adapted for use in bipolar disorder based mainly on those developed for use in other conditions. The present study involved the development and validation of a new patient self‐report measure specific to bipolar disorder, the Bipolar Functional Status Questionnaire (BFSQ). Methods: Relevant constructs were identified, evaluated, and refined through an expert advisory panel in conjunction with patient interviews. Questionnaire items were vetted through iterative patient interviews. Psychometric properties were determined based on patient responses from implementation of the proposed 33‐item questionnaire in an 11‐site study of 596 patients with bipolar disorder across varied phases of illness. Results: Eight constructs were identified as fundamental to functional status in bipolar disorder: cognitive function, sleep, role functioning, emotional functioning, energy/vitality, social functioning, personal management, and sexual functioning. Psychometric validation supported item reduction to a 24‐item unidimensional scale, with high internal consistency (coefficient α’s = 0.93–0.95), high test‐retest reliability (intraclass correlation coefficient = 0.86, 95% confidence interval = 0.82–0.89), strong convergent validity with other functional disability measures (r’s > 0.70), and highly significant discriminant validity across illness phases, with large effect sizes (Cohen’s d > 0.70). Conclusions: The BFSQ is a psychometrically sound self‐report measure that can be used to effectively quantify functional status across different clinical states in patients with bipolar disorder.  相似文献   
48.
叶表面角质层对草珊瑚生药鉴定的意义   总被引:4,自引:0,他引:4  
本文用扫描电镜对草珊瑚Sarcandra glabra(Thunb.)Nakai叶表角质层进行了研究,发现不同产地和同株不同发育程度草珊瑚叶表角质层雕纹型式均有一些差异。  相似文献   
49.
安宫牛黄丸中小檗碱的HPLC法测定   总被引:4,自引:0,他引:4  
本文报道用HPLC法测定黄连及含黄连中成药安宫牛黄丸中小檗碱型生物碱。实验结果表明选用硅胶柱为固定相,以醋酸乙酯—甲酸—乙醇(15:3:2)为流动相,能使样品中四种小檗碱型的生物碱获得最佳分离。用此法测得不同厂家生产的安宫牛黄丸中盐酸小檗碱的含量为0.331~0.456%,平均回收率为97.23%,变异系数为1.2%。  相似文献   
50.
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