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   1939篇
  免费   106篇
  国内免费   10篇
耳鼻咽喉   53篇
儿科学   80篇
妇产科学   33篇
基础医学   331篇
口腔科学   18篇
临床医学   145篇
内科学   292篇
皮肤病学   133篇
神经病学   244篇
特种医学   33篇
外科学   119篇
综合类   8篇
一般理论   1篇
预防医学   220篇
眼科学   22篇
药学   167篇
中国医学   4篇
肿瘤学   152篇
  2024年   3篇
  2023年   16篇
  2022年   43篇
  2021年   61篇
  2020年   34篇
  2019年   51篇
  2018年   54篇
  2017年   40篇
  2016年   57篇
  2015年   55篇
  2014年   63篇
  2013年   106篇
  2012年   162篇
  2011年   134篇
  2010年   79篇
  2009年   68篇
  2008年   121篇
  2007年   128篇
  2006年   124篇
  2005年   131篇
  2004年   115篇
  2003年   93篇
  2002年   123篇
  2001年   19篇
  2000年   12篇
  1999年   12篇
  1998年   17篇
  1997年   10篇
  1996年   16篇
  1995年   12篇
  1994年   7篇
  1993年   4篇
  1992年   9篇
  1991年   5篇
  1990年   6篇
  1989年   4篇
  1987年   4篇
  1986年   6篇
  1984年   3篇
  1983年   5篇
  1982年   7篇
  1981年   2篇
  1980年   3篇
  1978年   4篇
  1976年   4篇
  1975年   2篇
  1971年   3篇
  1970年   2篇
  1962年   2篇
  1960年   2篇
排序方式: 共有2055条查询结果,搜索用时 15 毫秒
81.
Invasive tumor or ductal carcinoma in situ occur in radial sclerosing lesions in one third of the cases therefore, surgical excision is mandatory. Forty-five patients with radial scar morphology were examined. Ultrasound guided fine-needle aspiration biopsy (FNAB) and core biopsy (CB) were performed in all cases. The postoperative pathological findings were compared to the results of preoperative biopsies. Sensitivity of preoperative percutaneous biopsies (FNAB and CB) was 17.6% and 70.6%, false-negative rate was 82.4% with FNAB and 29.4% with CB. The negative predictive value was 48.1% and 84.8% respectively. Had we done preoperative cytology only, we would have had to perform a two-step procedure (sentinel lymph node biopsy) in 7 patients (15.6%), while with preoperative core biopsy it has decreased to 2 patients (4.4%). Preoperative CB in small radial stellate lesions is recommended to achieve accurate diagnosis in order to avoid a two-step surgical procedures.  相似文献   
82.
83.
Aim The aim of this study was to investigate the influence of haemodialysis on plasma chromogranin A (CgA) concentration and to assess the relationship between CgA, blood pressure, occurrence of intradialytic hypotension episodes and residual renal function, respectively. Methods The study included 38 chronic haemodialysis patients (24 M, 14 F; mean age 56.2 ± 13.6 years). Plasma CgA and blood pressure were measured before and after a mid-week dialysis. Control group included 10 age- and sex-matched healthy subjects. Results Plasma CgA levels were on average 50-fold higher in HD patients than in the controls (699 ± 138 vs. 14 ± 6 U/L). In HD patients plasma CgA corrected for ultrafiltration rates significantly increased (to 836 ± 214 U/L, P < 0.001) at the end of dialysis procedure. In patients with (n = 8) and without frequent symptomatic intradialytic hypotension episodes predialysis values of CgA were similar (701 ± 169 vs. 698 ± 132 U/L) but post-dialysis were significantly lower in the former group (746 ± 312 vs. 860 ± 177 U/L; P = 0.03) despite a similar rate of ultrafiltration (2675 ± 1009 and 2583 ± 1311 ml, respectively). Accordingly, in patients with intradialytic hypotension an increase of plasma CgA during dialysis was also much lower than in patients without hypotension (45 ± 81 vs. 163 ± 144 U/L; P = 0.001). Conclusions CgA undergoes marked accumulation in renal failure. The increase of plasma CgA during dialysis is impaired in subjects with intradialytic hypotension episodes, which confirms the role of autonomic dysfunction in the pathogenesis of this complication.  相似文献   
84.
Chondrocytes are the main cells in the extracellular matrix (ECM) of articular cartilage and possess a highly differentiated phenotype that is the hallmark of the unique physiological functions of this specialised load-bearing connective tissue. The plasma membrane of articular chondrocytes contains a rich and diverse complement of membrane proteins, known as the membranome, which defines the cell surface phenotype of the cells. The membranome is a key target of pharmacological agents and is important for chondrocyte function. It includes channels, transporters, enzymes, receptors, and anchors for intracellular, cytoskeletal and ECM proteins and other macromolecular complexes. The chondrocyte channelome is a sub-compartment of the membranome and includes a complete set of ion channels and porins expressed in these cells. Many of these are multi-functional proteins with “moonlighting” roles, serving as channels, receptors and signalling components of larger molecular assemblies. The aim of this review is to summarise our current knowledge of the fundamental aspects of the chondrocyte channelome, discuss its relevance to cartilage biology and highlight its possible role in the pathogenesis of osteoarthritis (OA). Excessive and inappropriate mechanical loads, an inflammatory micro-environment, alternative splicing of channel components or accumulation of basic calcium phosphate crystals can result in an altered chondrocyte channelome impairing its function. Alterations in Ca2+ signalling may lead to defective synthesis of ECM macromolecules and aggravated catabolic responses in chondrocytes, which is an important and relatively unexplored aspect of the complex and poorly understood mechanism of OA development.  相似文献   
85.
Improvement in implant technology and the fact that children with cochlear implants have surpassed all expectations have led the field to believe that open-set speech understanding is a common and expected outcome. The available literature suggests this to be the case in open-set word understanding. This study shows the results of 41 pre-lingually deafened children with a minimum of 3 years' cochlear implant experience assessed on the EARS test battery, which includes open-set phoneme, word and sentence tests. Results show that some open-set skills emerge by 6 months after implantation. There was significant improvement over time, even after 3 years of cochlear implant experience. A significant effect of age at implantation was also demonstrated. Results suggest that cochlear-implanted children develop open-set speech recognition soon after implantation, and these skills develop over a long period of time, highlighting the need for continued therapy to maximize listening and learning.  相似文献   
86.
Alzheimer's disease (AD) in younger patients is associated with a higher prevalence of atypical symptoms. We examined neuropsychological performance according to age-at-onset. We assessed cognition in 172 patients with AD (81 early and 91 late onset) in five cognitive domains (memory, language, visuo-spatial functioning, executive functioning, attention). Dementia severity was assessed using the Mini-Mental State Examination (MMSE) and global cognitive decline using Cambridge Cognitive Examination (CAMCOG). Analyses of variance were performed with age-at-onset as between-subjects factor, and gender and education as covariates. Analysis was repeated after stratification for dementia severity (based on median MMSE). In early onset AD, age (mean ± SD) was 60 ± 4 years; 44 (54%) were female. In late onset AD, age was 72 ± 5 years; 47 (52%) were female. Dementia severity and global cognitive decline did not differ between groups (early onset: MMSE: 20 ± 5, CAMCOG: 69 ± 15, late onset: MMSE: 21 ± 5, CAMCOG: 70 ± 15; p > 0.05). Early onset patients performed worse than late onset patients on visuo-spatial functioning (p < 0.01), executive functioning (p < 0.001), and attention (p < 0.01). Late onset patients performed worse on memory, although not significantly (p = 0.11). Stratification for dementia severity showed that in mildly demented early onset patients, memory function was remarkably preserved compared to late onset patients (p < 0.01). In moderate AD, differences in memory function disappeared, but early onset patients performed worse on visuo-spatial functioning (p < 0.01), executive functioning (p < 0.001), and attention (p < 0.01) than late onset patients. Adjustment for APOE left results unchanged. In conclusion, early onset AD presents with a different cognitive profile and the disease course seems different. Relative sparing of memory function in early stages stresses the need to adequately test other cognitive domains.  相似文献   
87.
Our previous work demonstrated that the hormone response to stress and the negative feedback inhibition to these hormones are sex-dependently altered by prenatal morphine exposure in adult rats. An alteration in the glucocorticoid negative feedback inhibition is mediated by glucocorticoid receptors (GR) that are distributed throughout the brain, and mineralocorticoid receptors (MR) localized mainly in the hippocampus and involved in a tonic influence of brain functions. Therefore, the present study examined the binding characteristics of MR and GR in young adult male and female rats exposed prenatally (E11-E18) to morphine (10 mg/kg/2 x /day), saline or no treatment at all (controls). At 60-90 days of age, animals were adrenalectomized (ADX) 24 h prior to decapitation. The hippocampus and hypothalamus were dissected for saturation binding assays. The data demonstrate that prenatal stress due to maternal saline injections up-regulates MR and GR binding in the hippocampus of adult male rats and this effect is prevented by prenatal morphine exposure. There is no effect of prenatal morphine exposure on GR binding in the hypothalamus of males. In female rats, prenatal morphine exposure does not affect the binding of MR and GR in the hippocampus or GR in the hypothalamus relative to controls; however, they are affected by ovarian hormone fluctuation. Moreover, prenatal stress decreases MR binding in the hippocampus of diestrous females and GR binding in the hypothalamus of estrous females. Both decreases are prevented by prenatal morphine exposure. Thus, the present study demonstrates that: (1) prenatal stress due to maternal saline injections alters MR and GR binding of adult male and female rats and is prevented by prenatal morphine exposure; (2) the MR and GR binding in adult female rats are affected by ovarian hormone fluctuations.  相似文献   
88.
The study examines the psychometric properties of the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A) based on 717 (438 females and 279 males) healthy subjects in a Hungarian normative sample. The questionnaire is a self-report 110-item tool that postulates five affective temperaments: depressive, cyclothymic, irritable, hyperthymic, and anxious. Most of the TEMPS-A scales have excellent internal consistencies (0.78-0.84), except for the Depressive Temperament Scale, which had a Cronbach's alfa coefficient of 0.63. The item-analyses have identified a few deficient items which do not fit into the scale. In line with the literary data, women had higher mean scores on the depressive, cyclothymic, and anxious subscales, whereas men scored higher on the cyclothymic subscale. Cut-offs for each temperament were based on z-scores higher than + 2S.D. Dominant nervous-anxious (4.3%), depressive (3.8%), cyclothymic (3.2%), and irritable (3.2%) temperaments were the most common in this normative population, whereas dominant hyperthymic (1.8%) temperament was relatively uncommon. Factor analyses of the TEMPS-A items yielded considerable overlap between depressive and cognitive anxiety traits. The strongest correlation was observed between the anxious and the depressive temperament subscales in line with some international findings (r=0.62**). To test construct validity, we administered the Beck Depression Inventory, Profile of Mood States (shortened version) and the Cloninger Temperaments and Character Inventory, which all supported the validity of TEMPS-A subscales. Based on the results obtained with the Hungarian normative sample, the TEMPS-A is a reliable and valid instrument in personality psychology, and further refinement on clinical samples opens new and interesting research avenues.  相似文献   
89.
90.
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