全文获取类型
收费全文 | 586篇 |
免费 | 53篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 22篇 |
妇产科学 | 2篇 |
基础医学 | 107篇 |
口腔科学 | 11篇 |
临床医学 | 56篇 |
内科学 | 140篇 |
皮肤病学 | 10篇 |
神经病学 | 69篇 |
特种医学 | 7篇 |
外科学 | 68篇 |
综合类 | 3篇 |
预防医学 | 52篇 |
眼科学 | 4篇 |
药学 | 38篇 |
肿瘤学 | 43篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 30篇 |
2020年 | 19篇 |
2019年 | 25篇 |
2018年 | 29篇 |
2017年 | 14篇 |
2016年 | 22篇 |
2015年 | 33篇 |
2014年 | 22篇 |
2013年 | 45篇 |
2012年 | 66篇 |
2011年 | 57篇 |
2010年 | 25篇 |
2009年 | 27篇 |
2008年 | 43篇 |
2007年 | 34篇 |
2006年 | 30篇 |
2005年 | 31篇 |
2004年 | 20篇 |
2003年 | 20篇 |
2002年 | 14篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有641条查询结果,搜索用时 31 毫秒
91.
92.
Ashley V. Hill Natacha M. De Genna Maria J. Perez-Patron Tamika D. Gilreath Carmen Tekwe Brandie DePaoli Taylor 《The Journal of adolescent health》2019,64(3):319-326
Purpose
Syndemic theory suggests that the convergence of social, environmental, and ecological factors can interact to exacerbate behavioral health problems and are often intensified by social conditions and disparities. This study used latent class analysis (LCA) to determine gender and racial/ethnic specific classes for sexually transmitted infection (STI) risk.Methods
LCA included 18 measured socioeconomic, depression, substance use, and sexual behavioral variables from 1,664 young adults ages 18–25 in the NHANES. Models were stratified by gender and then by race/ethnicity. Logistic regression determined associations between latent class membership and testing positive for one or more STIs (Chlamydia trachomatis, HIV or herpes simplex virus-II). For each stratified analysis, classes with the lowest probability of reported risk factors in the LCA were the reference groups.Results
Class 3 in females (highest probability of reporting both socioeconomic and behavioral factors) and class 3 in males (majority behavioral factors) had increased odds of STI (females: OR?=?2.7, 95% CI 1.6–4.5; males: OR 2.5, 95% CI 1.3–4.6). By race for females, depression (highest in Hispanics), poverty, and less educated households (highest in blacks and Hispanics) were evident in classes associated with STI. Class 1 black males (majority behavioral factors) had a higher odds of STI compared with low risk white males (OR?=?16.4 95% CI 3.7–72.0) However, no other associations were observed among males.Conclusions
Risk patterns for STI differed by gender and race/ethnicity. Consistent with syndemic theory, effective STI interventions need to address socioeconomic factors and mental health rather than individual behaviors, particularly for minority women. 相似文献93.
Sara Pereira Peter T. Katzmarzyk Thayse Natacha Gomes Alessandra Borges Daniel Santos Michele Souza Fernanda K. dos Santos Raquel N. Chaves Catherine M. Champagne Tiago V. Barreira José A.R. Maia 《Nutrients》2015,7(6):4345-4362
Obesity in children is partly due to unhealthy lifestyle behaviours, e.g., sedentary activity and poor dietary choices. This trend has been seen globally. To determine the extent of these behaviours in a Portuguese population of children, 686 children 9.5 to 10.5 years of age were studied. Our aims were to: (1) describe profiles of children’s lifestyle behaviours; (2) identify behaviour pattern classes; and (3) estimate combined effects of individual/socio-demographic characteristics in predicting class membership. Physical activity and sleep time were estimated by 24-h accelerometry. Nutritional habits, screen time and socio-demographics were obtained. Latent Class Analysis was used to determine unhealthy lifestyle behaviours. Logistic regression analysis predicted class membership. About 78% of children had three or more unhealthy lifestyle behaviours, while 0.2% presented no risk. Two classes were identified: Class 1-Sedentary, poorer diet quality; and Class 2-Insufficiently active, better diet quality, 35% and 65% of the population, respectively. More mature children (Odds Ratio (OR) = 6.75; 95%CI = 4.74–10.41), and boys (OR = 3.06; 95% CI = 1.98–4.72) were more likely to be overweight/obese. However, those belonging to Class 2 were less likely to be overweight/obese (OR = 0.60; 95% CI = 0.43–0.84). Maternal education level and household income did not significantly predict weight status (p ≥ 0.05). 相似文献
94.
Varying proliferative and clonogenic potential in NRAS‐mutated congenital melanocytic nevi according to size
下载免费PDF全文
![点击此处可从《Experimental dermatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sarah Guégan Natacha Kadlub Arnaud Picard Thomas Rouillé Christelle Charbel Aurore Coulomb‐L'Hermine Alexandre How‐Kit Sylvie Fraitag Selim Aractingi Romain H. Fontaine 《Experimental dermatology》2016,25(10):789-796
Congenital melanocytic nevi (CMN) are benign proliferations that may be associated with various consequences depending on their size. They are characterized by a specific molecular signature, namely a postzygotic somatic NRAS or BRAF mutation. We have recently reported that large CMN (lCMN), which are classically associated with an increased melanoma risk, harbour cell subpopulations with specific clonogenic and tumorigenic potential. We wished to ascertain whether cells displaying similar properties persisted postnatally in medium CMN (mCMN). Eighteen medium M1, nine large and one giant NRAS‐mutated CMN were prospectively included in the study. Subpopulations of mCMN cells expressed stem cell/progenitor lineage markers such as Sox10, nestin and Oct4, as was the case in lCMN. Nevertheless, conversely to lCMN, mCMN cells with clonogenic properties were rarer. In vitro, approximatively one in 1500 cells isolated from fresh mCMN formed colonies that could be passaged. In vivo, mCMN seemed to harbour cells with less proliferative potential than the larger lesions as lCMN biopsies displayed a threefold expansion compared to mCMN when xenografted in Rag2?/? mice. Thus, our data revealed variations in clonogenicity and tumorigenic properties in NRAS‐mutated CMN according to size. 相似文献
95.
Comparison of the Bordetella pertussis and Bordetella parapertussis isolates circulating in Saint Petersburg between 1998 and 2000 with Russian vaccine strains
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kourova N Caro V Weber C Thiberge S Chuprinina R Tseneva G Guiso N 《Journal of clinical microbiology》2003,41(8):3706-3711
We analyzed the Bordetella pertussis and Bordetella parapertussis isolates circulating in Saint Petersburg that were collected between 1998 and 2000 and compared them with isolates collected 40 years ago and Russian vaccine strains. The analysis involved serotyping, pulsed-field gel electrophoresis of chromosomal DNA after digestion with XbaI and SpeI, and sequencing of the ptxS1 and prn genes, which encode the S1 subunit of the pertussis toxin and the major adhesin pertactin, respectively. The Russian isolates were classified in five of the six pulsed-field gel electrophoresis groups identified in other European countries. The B. pertussis isolates currently circulating in Saint Petersburg differed from the Russian whole-cell vaccine strains and the isolates collected in the prevaccine era. However, their repartition in the major pulsed-field gel electrophoresis groups was slightly different from that of isolates collected in countries that have had a high level of vaccine coverage for a long time, probably because the level of vaccine coverage in Saint Petersburg has increased only recently, after decreasing until the early 1990s. Most of the B. parapertussis isolates studied were similar to those circulating in France. However, some variants were observed, perhaps because B. parapertussis infections are more common in children in this area. 相似文献
96.
97.
98.
Rossio Motta-Ochoa Karine Bertrand Jorge Flores-Aranda Catherine Patenaude Natacha Brunelle Michel Landry Serge Brochu 《International journal of mental health and addiction》2017,15(4):883-899
People with mental disorders (MD) have high rates of substance use problems (SUP) that are undertreated and understudied despite their adverse outcomes. The objective of this study is to examine barriers and facilitators that influence help-seeking to addiction treatment from the perspective of people with co-occurring MD and SUP. Forty-three individuals with MD and SUP were selected from the sample (n = 127) of a larger research project. This sub-group participated in semi-structured interviews and completed questionnaires. Interview contents were thematically analyzed using a trajectory approach. Based on participants’ addiction trajectories, two mental health experiences were identified: the “multiple disorders experience” and the “anxiety disorder experience.” The analysis highlighted how participants relate to barriers and facilitators to addiction help-seeking at the individual level (denial/minimization of problematic drug use, fear of being labeled an addict, influence of social networks, and knowledge of addiction services) and health system level (waiting time, costs, relationships with health providers, therapeutic approaches, and availability of psychological support). Interventions should be sensitive to the different experiences of people with MD and SUP. Integrated addiction services and a “no wrong door” approach are suggested. 相似文献
99.
100.
Muppidi JR Arnon TI Bronevetsky Y Veerapen N Tanaka M Besra GS Cyster JG 《The Journal of experimental medicine》2011,208(10):1941-1948
Specialized B cells residing in the splenic marginal zone (MZ) continuously survey the blood for antigens and are important for immunity to systemic infections. However, the cues that uniquely attract cells to the MZ have not been defined. Previous work demonstrated that mice deficient in cannabinoid receptor 2 (CB2) have decreased numbers of MZ B cells but it has been unclear whether CB2 regulates MZ B cell development or positioning. We show that MZ B cells are highly responsive to the CB2 ligand 2-arachidonylglycerol (2-AG) and that CB2 antagonism rapidly displaces small numbers of MZ B cells to the blood. Antagonism for longer durations depletes MZ B cells from the spleen. In mice deficient in sphingosine-1-phosphate receptor function, CB2 antagonism causes MZ B cell displacement into follicles. Moreover, CB2 overexpression is sufficient to position B cells to the splenic MZ. These findings establish a role for CB2 in guiding B cells to the MZ and in preventing their loss to the blood. As a consequence of their MZ B cell deficiency, CB2-deficient mice have reduced numbers of CD1d-high B cells. We show that CB2 deficiency results in diminished humoral responses to a CD1d-restricted systemic antigen. 相似文献