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   51821篇
  免费   3208篇
  国内免费   246篇
耳鼻咽喉   650篇
儿科学   1187篇
妇产科学   1232篇
基础医学   7182篇
口腔科学   1505篇
临床医学   5697篇
内科学   11130篇
皮肤病学   815篇
神经病学   5095篇
特种医学   1816篇
外科学   6581篇
综合类   334篇
一般理论   44篇
预防医学   3669篇
眼科学   842篇
药学   3510篇
  1篇
中国医学   60篇
肿瘤学   3925篇
  2023年   325篇
  2022年   636篇
  2021年   1157篇
  2020年   757篇
  2019年   993篇
  2018年   1219篇
  2017年   1079篇
  2016年   1267篇
  2015年   1326篇
  2014年   1760篇
  2013年   2532篇
  2012年   3844篇
  2011年   4045篇
  2010年   2393篇
  2009年   2187篇
  2008年   3351篇
  2007年   3640篇
  2006年   3255篇
  2005年   3323篇
  2004年   3051篇
  2003年   2847篇
  2002年   2600篇
  2001年   474篇
  2000年   404篇
  1999年   525篇
  1998年   579篇
  1997年   470篇
  1996年   421篇
  1995年   362篇
  1994年   313篇
  1993年   320篇
  1992年   265篇
  1991年   244篇
  1990年   222篇
  1989年   243篇
  1988年   216篇
  1987年   180篇
  1986年   188篇
  1985年   218篇
  1984年   189篇
  1983年   173篇
  1982年   193篇
  1981年   162篇
  1980年   139篇
  1979年   120篇
  1978年   126篇
  1977年   133篇
  1976年   98篇
  1975年   112篇
  1974年   89篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
PURPOSE: A role for estrogens in determining lung cancer risk and prognosis is suggested by reported sex differences in susceptibility and survival. Archival lung tissue was evaluated for the presence of nuclear estrogen receptor (ER)-alpha and ER-beta and the relationship between ER status, subject characteristics, and survival. EXPERIMENTAL DESIGN: Paraffin-embedded lung tumor samples were obtained from 214 women and 64 men from two population-based, case-control studies as were 10 normal lung autopsy samples from patients without cancer. Nuclear ER-alpha and ER-beta expression was determined by immunohistochemistry. Logistic regression was used to identify factors associated with ER positivity and Cox proportional hazards models were used to measure survival differences by ER status. RESULTS: Neither tumor (0 of 94) nor normal (0 of 10) lung tissue stained positive for ER-alpha. Nuclear ER-beta positivity was present in 61% of tumor tissue samples (170 of 278; 70.3% in men and 58.3% in women) and 20% of normal tissue samples (2 of 10; P = 0.01). In multivariate analyses, females were 46% less likely to have ER-beta-positive tumors than males (odds ratio, 0.54; 95% confidence interval, 0.27-1.08). This relationship was stronger and statistically significant in adenocarcinomas (odds ratio, 0.40; 95% confidence interval, 0.18-0.89). Women with ER-beta-positive tumors had a nonsignificant 73% (P = 0.1) increase in mortality, whereas men with ER-beta-positive tumors had a significant 55% (P = 0.04) reduction in mortality compared with those with ER-beta-negative tumors. CONCLUSIONS: This study suggests differential expression by sex and influence on survival in men of nuclear ER-beta in lung cancer, particularly in adenocarcinomas.  相似文献   
42.
OBJECTIVES: CD62L was evaluated as a determinant of human pre-effector T cells. STUDY DESIGN AND SETTING: Phenotype and cytokine secretion profiles of CD62L cells were determined based on activation status. RESULTS: CD62L(Low) T cells demonstrated significantly higher secretion of interleukin (IL)-10 and interferon (IFN)-gamma than did CD62L(High) T cells. After activation, the majority of cells expressed high levels of the CD62L surface marker. Postactivation levels of IL-10 production remained elevated or unchanged. In a murine B16 melanoma model, freshly isolated CD62L(Low) tumor draining lymph nodes (TDLN) T cells showed increased secretion of IL-2 and IL-4 but not of IL-10 or IFN-gamma. The surface expression of CD62L and cytokine secretion patterns were maintained after activation with concomitant increases in IL-10. CONCLUSION: Our results provide evidence that CD62L(Low) T cells in TDLNs of progressively growing squamous cell carcinoma of the head and neck differ phenotypically and functionally from those of mouse origin. SIGNIFICANCE: Characterization of this human CD62L(Low) T cell population provides initial insight regarding novel surface markers in TDLN T cells that might correlate with antitumor reactivity.  相似文献   
43.
The objective of this review is to identify and review publications describing the impact of reduced somatosensation on balance. Based on knowledge of the association between specific somatosensory loss and deterioration of balance, conclusions can be made about role of somatosensation in standing balance.A systematic literature review is presented in which publications from the years 1993 through 2007 were searched in Medline and Embase. Medical Subject Headings (MESH) terms and free text words (related to balance, somatosensory loss, and lower limb) were used to perform the searches. Fifteen articles were selected for detailed review based on predetermined inclusion criteria, and three of the included articles described the effect of experimentally reduced somatosensation on balance in healthy subjects. Ten of the articles described balance in diabetic neuropathy (DN). The last two included articles described balance in Charcot-Marie-Tooth (CMT) disease type 1A (CMT1A) or type 2 (CMT2).The literature indicates that the tactile sensation is reduced in DN, CMT1A, and CMT2 and when the plantar surface of the feet was hypothermically anesthetized. Joint motion sensation seems to be impaired in patients with DN, and passive joint position sensation appears to be reduced in healthy subjects with anesthesia of ankle and foot from prolonged ischemia. This reduced somatosensation seems to have a negative effect on balance in patients with DN and CMT2; however, this appeared not to be the case in patients with CMT1A and in healthy subjects.  相似文献   
44.
The Eating Disorder Inventory, Version 2 (EDI‐2) is a questionnaire used clinically and in research all over the world. EDI‐2 is cross‐culturally valid, yet normative values may depend on culture. Norms and reliability of the Danish version have to date been lacking, and will be presented in this article, comparing patients (N = 575) and controls (N = 881). Also, internal reliability of scales is tested for both groups. Differences between norms of the Danish and the North American version of EDI were small but significant for all scales except asceticism (eating disorder patients) and ineffectiveness, interpersonal distrust and maturity fears (normal controls). For both groups the internal consistency was >0.70 for all subscales except asceticism. Although differences across the eating disorder diagnostic groups were dubious, the EDI‐2 is useful to screen for eating problems in the general population as well as to rate progress and outcome among eating disorder patients. Copyright © 2009 John Wiley & Sons, Ltd and Eating Disorders Association.  相似文献   
45.
Iron deficiency may exacerbate symptoms in the Restless Legs Syndrome (RLS). We investigated the effect of intravenous iron sucrose or placebo on symptoms in patients with RLS and mild to moderate iron deficit. Sixty patients with primary RLS (seven males, age 46 (9) years, S‐ferritin ≤45 μg/L) recruited from a cohort of 231 patients were randomly assigned in a 12‐months double‐blind, multi‐centre study of iron sucrose 1000 mg (n = 29) or saline (n = 31). The primary efficacy variable was the RLS severity scale (IRLS) score at week 11. Median IRLS score decreased from 24 to 7 (week 11) after iron sucrose and from 26 to 17 after placebo (P = 0.123, N.S. for between treatment comparison). The corresponding scores at week 7 were 12 and 20 in the two groups (P = 0.017). Drop out rate because of lack of efficacy at 12 months was 19/31 after placebo and 5/29 patients after iron sucrose (Kaplan–Meier estimate, log rank test P = 0.0006) suggesting an iron induced superior long term RLS symptom control. Iron sucrose was well tolerated. This study showed a lack of superiority of iron sucrose at 11 weeks but found evidence that iron sucrose reduced RLS symptoms both in the acute phase (7 weeks) and during long‐term follow up in patients with variable degree of iron deficiency. Further studies on target patient groups, dosing and dosing intervals are warranted before iron sucrose could be considered for treatment of iron deficient patients with RLS. © 2009 Movement Disorder Society  相似文献   
46.
The goal of this longitudinal study was to investigate the precursors of early reading development in 52 children with cerebral palsy at kindergarten level in comparison to 65 children without disabilities. Word Decoding was measured to investigate early reading skills, while Phonological Awareness, Phonological Short-term Memory (STM), Speech Perception, Speech Production and Nonverbal Reasoning were considered reading precursors. Children with cerebral palsy lag behind on all reading precursors at the beginning of the second year of kindergarten. For the children without disabilities, early reading skills in Grade 1 were best predicted by Phonological Awareness and Phonological STM while Speech Production was the most important predictor of early reading success for the children with cerebral palsy, followed by Phonological Awareness and Speech Perception. Furthermore, for children with cerebral palsy, Speech Production appears to dominate reading development, as Speech Production measured at the beginning of the second year of kindergarten was strongly predictive of all other reading precursors measured at the end of the second year of kindergarten. The results of this study reveal that children with cerebral palsy with additional speech impairments are at risk for limited literacy development. Clinical implications are discussed.  相似文献   
47.
48.
49.
50.
Summary The aim of the present study was to investigate the discriminative power of a series of variables (including determination of depressive symptomatology by means of a visual analogue scale, determination of personality traits by means of the Karolinska Scales of Personality, determination of monoamine metabolites in CSF, platelet MAO activities, serum cortisol before and after dexamethasone suppression and urinary melatonin) in differentiating (a) chronic pain patients from healthy subjects, and (b) patients with idiopathic pain syndromes from patients with neurogenic pain syndromes. Separately each of the measures gave a significant but often low contribution to the discrimination, while a combination of several measures gave a complete discrimination both between healthy subjects and patients with chronic pain syndromes and between patients with idiopathic and neurogenic pain syndromes, respectively.Supported in part by grants from the Swedish Medical Research Council (grants no. 3371, 4145 and 5740) and by a grant from Stiftelsen Söderström-Königska Sjukhemmet  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