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   2445篇
  免费   173篇
  国内免费   8篇
耳鼻咽喉   60篇
儿科学   70篇
妇产科学   124篇
基础医学   289篇
口腔科学   116篇
临床医学   176篇
内科学   488篇
皮肤病学   23篇
神经病学   356篇
特种医学   70篇
外科学   263篇
综合类   18篇
一般理论   2篇
预防医学   178篇
眼科学   43篇
药学   116篇
中国医学   7篇
肿瘤学   227篇
  2023年   16篇
  2022年   16篇
  2021年   62篇
  2020年   41篇
  2019年   61篇
  2018年   106篇
  2017年   75篇
  2016年   92篇
  2015年   82篇
  2014年   111篇
  2013年   113篇
  2012年   173篇
  2011年   168篇
  2010年   112篇
  2009年   74篇
  2008年   130篇
  2007年   137篇
  2006年   157篇
  2005年   122篇
  2004年   116篇
  2003年   108篇
  2002年   93篇
  2001年   55篇
  2000年   49篇
  1999年   52篇
  1998年   14篇
  1997年   6篇
  1996年   11篇
  1995年   12篇
  1994年   9篇
  1992年   13篇
  1991年   26篇
  1990年   28篇
  1989年   23篇
  1988年   9篇
  1987年   12篇
  1986年   11篇
  1985年   14篇
  1984年   9篇
  1983年   5篇
  1982年   6篇
  1980年   8篇
  1979年   7篇
  1978年   9篇
  1977年   4篇
  1974年   4篇
  1973年   7篇
  1972年   4篇
  1971年   6篇
  1927年   4篇
排序方式: 共有2626条查询结果,搜索用时 15 毫秒
91.
IntroductionThe usage of extended-criteria donors (ECD) became a routinely accepted manner in the last decade. ECD is a potential risk factor for antibody-mediated rejection. Analysis of lymphocyte subsets might be a complementary diagnostic toolkit because there is limited knowledge about this term.MethodBetween May 12, 2016, and September 4, 2019, a total of 130 patients who had undergone kidney transplant were investigated. Patients were divided in ECD and standard criteria donor (SCD) groups. Blood samples were collected before the operation, then in the first week and after 30, 60, 180, and 365 days. Besides routine laboratory tests, multicolor flow cytometry was performed for lymphocyte subsets.ResultsECD grafts were transplanted to older recipients. The number of CD4+ cells increased in the SCDs from the first week to until the end of first month, and then decreased. The number of CD4+ cells decreased from the beginning of the study until the end of first year to 66% of its original value in ECDs. At the first month, the number of CD19+ cells was higher in SCD compared with ECD cases; the number then decreased in both groups. T-regulatory cells had a drop at the first week that lasted until the first month. A bigger increase in SCD and a moderate increase in ECD group were then observed. The kinetics of CD19+ and CD19+ naive cells are similar in the ECD and SCD groups. In the SCD group, cell count decreased in both CD19+ (13%) and CD19+ naive (12%) between third and sixth month. The count of CD19+ cells decreased by 9%, but the count of CD19+ naive cells increased by 11% between the sixth month and first year.DiscussionThe prolonged postoperative uremic state caused by the poorer initial function, together with an aging immune system, explains the weaker immune response in ECD patients, which may be the cause of the decreased number of memory and regulatory T cells. Older patients with an ECD graft need a tailored, personalized, and less aggressive immunosuppressive treatment.  相似文献   
92.
OBJECTIVE: This study was designed to evaluate the efficacy and safety of a highly potent and selective serotonergic antidepressant, escitalopram, in the treatment of bipolar depression. METHOD: Twenty outpatients with DSM-IV bipolar depression types I and II were enrolled in a 12-week open trial of escitalopram, 10 mg daily, adjunctive to their ongoing mood stabilizer. Assessments were carried out using the Hamilton Rating Scale for Depression (HAM-D), the Young Mania Rating Scale (YMRS), and the Clinical Global Impressions for Severity (CGI-S) and Improvement (CGI-I) scales. The study was conducted from August 2003 to February 2004. RESULTS: Escitalopram was associated with significant improvement as measured by the HAM-D total score, which showed a mean reduction from baseline (mean = 20.9, SD = 4.2) to endpoint (mean = 8.9, SD = 3.6; p < .001) of 12 points. The mean CGI-S score decreased by 3.3 points (baseline: mean = 4.8, SD = 0.7; week 12: mean = 1.5, SD = 0.6; p < .001). Adverse events emerged in 75% of the patients (N = 15), usually of mild-to-moderate severity. Four dropouts took place due to manic switch (N = 1), hypomanic symptoms (N = 2), and hospitalization due to the emergence of suicidal ideation and psychosis (N = 1). CONCLUSION: These findings suggest that escitalopram in association with mood stabilizers may be an effective and reasonably well-tolerated treatment for patients with moderate-to-severe bipolar depression. The switch rate was similar to what is described in the literature for the selective serotonin reuptake inhibitors. Randomized controlled trials of escitalopram in bipolar depression are warranted.  相似文献   
93.

Purpose

Toll-like receptors (TLRs) have an important role in the activation of both innate and adaptive immunity in response to pathogens and endogenous danger signals from damaged or dying cells. The aim of this study was to determine the relationship between urothelial carcinoma (UC) and TLR expression.

Basic procedures

Real-time polymerase chain reaction evaluation was made of the messenger RNA expression of TLRs 1–10 in 24 UC samples and 46 nontumoral bladder tissue samples. The levels of proinflammatory cytokines (IL-1β, IL-6, and IL-8) in the urine samples were also determined with enzyme-linked immunosorbent assay.

Main findings

TLR2–7 and TLR10 expressions were significantly higher in UC than in the control group (P<0.05 for all comparisons). No concordance was found between matched tumor tissue and urine samples in terms of TLR expression. IL-1β, IL-6, and IL-8 levels were significantly higher in urine specimens of patients with UC (P = 0.033, P = 0.001, and P = 0.008, respectively).

Principal conclusions

The results of this study demonstrated that the TLR gene expression profiles reflect the heterogeneity within UC. These results might also prompt further investigation to better understand the role of the TLR gene family expression in the tumor progression of UC.  相似文献   
94.
We aimed to correlate the predisposing demographic and clinical factors for erectile dysfunction (ED) in young men and treatment response in these men with data from older men. The patients were divided into two groups: <40 years (group I, n = 58) and ≥40 years (group II, n = 73). ED was evaluated with the International Index of Erectile Function-5 (IIEF-5) questionnaire, and Beck's Depression Inventory (BDI) questionnaire was used to evaluate mood status. The number of patients with morning rigidity and normal libido was higher in group I (70.7% vs. 16.4%, p = .039 and 72% vs. 37%, p = .047). The increase in scores other than IIEF-Orgasmic Function and Sexual Desire domain scores after treatment was higher in the first group (p = .029, p = .035 and p < .001 respectively). In multivariate analysis, the factors predicting the low IIEF-Erectile Function domain score in young men were testosterone level and BDI score (p = .026 and p = .034). Although psychogenic factors contribute significantly to the aetiology of ED, hormone profile is more preserved in young men than in older men.  相似文献   
95.
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   
96.
Objective To investigate whether abnormal eating behaviors in young women could predict eating disorders after 4 years. Method 56 women were identified as presenting abnormal eating behaviors in a cross-sectional study (Eating Attitudes Test-26 and Edinburgh Bulimic Investigation Test). They were matched for age and neighborhood to two controls (n = 112). Four years later, they were re-assessed with the two screening questionnaires plus the Composite International Diagnostic Interview (CIDI 2.1). Results Women with abnormal eating behaviors at baseline showed a high probability of presenting abnormal eating behaviors but it was not associated with eating disorders 4 years later. They were also at higher risk for obsessive–compulsive disorder, post-traumatic stress disorder, and specific phobia. Discussion Abnormal eating behaviors were related to the maintenance of the disturbed behavior over the years, and were associated with increased probability for psychiatric diagnoses.  相似文献   
97.
Purpose

It was expected that using a comprehensive scale like the Thought and Language Disorder Scale (TALD) for measurement of FTD would enable assessing its heterogeneity and its associations with cognitive impairment and functionality. This study has aimed to analyze the relationship between formal thought disorder (FTD) and cognitive functions, functionality, and quality of life in schizophrenia.

Methods

This cross-sectional exploratory study included 46 clinical participants meeting the DSM-5 diagnostic criteria for schizophrenia and 35 healthy individuals as the control groups. Data were acquired by means of the Turkish language version of the TALD, the Positive and Negative Syndrome Scale, the Clinical Global Impression Scale, the Functioning Assessment Short Test, the Social Functioning Scale, the World Health Organization Quality of Life Instrument-Short Form, and a neuropsychological test battery on executive functions, working memory, verbal fluency, abstract thinking, and response inhibition. Correlation analyses were conducted to detect significant relationships.

Results

The clinical group scored failures in all cognitive tests. The objective positive FTD was associated with deficits in executive functions and social functioning. The objective negative FTD was associated with poor performance in all cognitive domains, physical quality of life, and social and global functioning. The subjective negative FTD was negatively correlated with psychological quality of life.

Conclusion

This study demonstrated that objective FTD factors reflect different underlying cognitive deficits and correlate with different functioning domains. Significant correlation was determined between subjective negative FTD and psychological quality of life. Given the close relationship of FTD with functioning and quality of life, the FTD-related cognitive deficits should be the key treatment goal in schizophrenia.

  相似文献   
98.
Objectives:  Systematic parsing of executive function processes is critical for the development of more specific models of neurobiological processes mediating disturbed cognition in youth with bipolar disorder (BPD).
Methods:  A sample of 33 children and adolescents with bipolar I disorder (BPD I) (mean age 12.1 ± 3.0 years, 39% female) and 44 demographically matched healthy participants (mean age 12.9 ± 2.8 years, 50% female) completed a neurocognitive battery including measures aimed at detection of disruption in prefrontal cortical circuitry (i.e., working memory, set shifting, and rule attainment).
Results:  Compared to healthy controls, BPD I children exhibited significant deficits in spatial working memory, visual sequencing and scanning, verbal fluency and abstract problem solving, particularly when a memory component was involved. In our spatial delayed response task, memory set size was parametrically varied; the performance pattern in BPD I children suggested deficits in short-term memory encoding and/or storage, rather than capacity limitations in spatial working memory. Earlier age at onset of illness and antipsychotic medication usage were associated with poorer performance on speeded information-processing tasks; however, severity of mood symptomatology and comorbidity with disruptive behavior disorders were not associated with task performance.
Conclusions:  These results suggest impairment in measures of prefrontal cortical function in juvenile BPD I that are similar to those seen in the adult form of the illness, and implicate both the ventral and dorsolateral prefrontal cortex as loci of pathology in juvenile BPD. As these deficits were not associated with clinical state or comorbidity with other disorders, they may reflect trait-related impairments, a hypothesis that will be pursued further in longitudinal studies.  相似文献   
99.
Some authors have reported an association of BDNF Val66Met polymorphism with suicidal behavior and/or clinical aspects of suicidal attempts. We evaluated, here, the impact of BDNF Val66Met polymorphism on the clinical characteristics of suicide attempts. The study was conducted on a cohort of 120 consecutive patients who were admitted to the Emergency Hospital of Porto Alegre, Brazil, due to a suicide attempt. Variables of univariate analyses were included in a logistic regression model to test whether the risk factors had independent effect. In univariate analyses, sex, BDNF genotype, intent and method of suicide attempt were all risk factors for high lethality in suicide attempts. After logistic regression analysis, male sex (O.R. = 3.03; 95% C.I = 1.34–6.84; 0.008) and the presence of BDNF 66Met allele (O.R. = 2.62; 95% C.I = 1.04–6.57; 0.04) were significantly and independently associated with the high lethality in suicide attempts. The present study showed that BDNF 66Met allele is an independent predictor of high lethality in suicide attempts of depressed patients. This finding is important because it might allow earlier identification of patients at high risk for suicide, perhaps providing better tools for clinical care of these patients in the future.  相似文献   
100.

Background  

Guillain–Barre syndrome (GBS) is a well known entity that has many infectious agents reported as antecedent events. The spectrum of GBS includes acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), acute motor sensory axonal neuropathy (AMSAN), and some other variants like Miller-Fisher syndrome (MFS).  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