全文获取类型
收费全文 | 5960篇 |
免费 | 485篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 252篇 |
妇产科学 | 130篇 |
基础医学 | 759篇 |
口腔科学 | 62篇 |
临床医学 | 1101篇 |
内科学 | 1039篇 |
皮肤病学 | 87篇 |
神经病学 | 439篇 |
特种医学 | 176篇 |
外科学 | 529篇 |
综合类 | 189篇 |
一般理论 | 4篇 |
预防医学 | 768篇 |
眼科学 | 50篇 |
药学 | 507篇 |
中国医学 | 4篇 |
肿瘤学 | 331篇 |
出版年
2023年 | 26篇 |
2022年 | 45篇 |
2021年 | 115篇 |
2020年 | 71篇 |
2019年 | 125篇 |
2018年 | 120篇 |
2017年 | 105篇 |
2016年 | 113篇 |
2015年 | 128篇 |
2014年 | 167篇 |
2013年 | 312篇 |
2012年 | 433篇 |
2011年 | 415篇 |
2010年 | 247篇 |
2009年 | 207篇 |
2008年 | 413篇 |
2007年 | 414篇 |
2006年 | 408篇 |
2005年 | 418篇 |
2004年 | 409篇 |
2003年 | 384篇 |
2002年 | 380篇 |
2001年 | 58篇 |
2000年 | 61篇 |
1999年 | 66篇 |
1998年 | 76篇 |
1997年 | 49篇 |
1996年 | 50篇 |
1995年 | 44篇 |
1994年 | 31篇 |
1993年 | 28篇 |
1992年 | 33篇 |
1991年 | 33篇 |
1990年 | 47篇 |
1989年 | 37篇 |
1988年 | 24篇 |
1987年 | 31篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 22篇 |
1983年 | 24篇 |
1982年 | 16篇 |
1981年 | 23篇 |
1979年 | 15篇 |
1978年 | 21篇 |
1977年 | 15篇 |
1976年 | 17篇 |
1975年 | 18篇 |
1973年 | 15篇 |
1972年 | 15篇 |
排序方式: 共有6469条查询结果,搜索用时 15 毫秒
31.
Dr. Alphonse E. Sirica PhD Lynne W. Elmore BA Nobuya Sano MD 《Digestive diseases and sciences》1991,36(4):494-501
A novel intrahepatic biliary cell culture/in vivo transplantation system has been developed with an essentially pure population of bile ductular epithelial cells isolated from rat liver 6–12 weeks after bile duct ligation. In primary culture, these cells retain staining strongly for -glutamyltranspeptidase and glutathione S-transferase P. The cytoplasm of cultured bile ductular cells reacts with an anti-laminin antibody, but loses immunoreactivity with a monoclonal anti-cytokeratin 19 antibody. Semiconservative DNA synthesis in the cultured cells was dependent upon the continued presence of 10% fetal calf serum in the medium. Replicating bile ductular cells could be subcultured for a finite number of passages. In addition, freshly isolated bile ductular epithelial cells gave rise to well differentiated bile ductular structures when transplanted into the interscapular fat pads of syngeneic recipient rats.Presented at the Proceedings of the International Meeting on Normal and Neoplastic Growth in Hepatology, Bari, Italy, June 1989.This work was supported by USPHS Grant RO1 CA39225 to Dr. Sirica by the National Cancer Institute, Department of Health and Human Services. 相似文献
32.
A free exploration test was used to examine the effects of LSD on investigatory responding and locomotor activity in a novel environment. Rats were injected with 20–30 g/kg LSD or saline prior to being placed in a home cage. After 10 min, a door was opened permitting entry into a larger holeboard chamber where crossovers, rearings, hole pokes, and routes of locomotion were monitored. When administered either 10 or 30 min prior to testing, LSD reduced the time spent in the holeboard chamber only during the first half of a 1-h session, resulting in a corresponding reduction in all holeboard activity measures. In the subsequent 30 min, LSD-treated rats maintained a steady level of responding, in contrast to the continual derement exhibited by controls. Despite their initial avoidance of the holeboard, LSD-treated rats made consistently longer hole pokes into floor holes and showed a more diversified pattern of locomotion than did controls throughout the 1-h session. Most striking was the failure of LSD-treated rats to establish the stereotyped excursion routes, characteristic of controls, from the home cage to various parts of the holeboard. It is suggested that LSD potentiates both neophobic (avoidance) and investigatory responses to a novel environment by retarding the rate of behavioral habituation. 相似文献
33.
Koziol-McLain J Giddings L Rameka M Fyfe E 《Journal of Midwifery & Women's Health》2008,53(6):504-510
The identification of intimate partner violence (IPV) against women as a public health problem has led to routine health care site– based screening and brief intervention policies. However, there is a lack of evidence supporting the usefulness and safety of such policies. Our objective was to ascertain the acceptability, usefulness, and harm of a brief health care site– based screening intervention. In this qualitative study, semistructured interviews were conducted with 36 women several weeks after a standardized screening intervention in either an emergency department (adult and paediatric) or primary health care setting. The majority of women (97%) welcomed the IPV screening intervention and perceived it as nonthreatening and safe. The women reported no increased risk of harm because of the screening. The responses showed that the intervention had a therapeutic and educational quality, and the attitude and approach of the person asking the intervention questions was critical to a positive outcome. Women without a history of violence cautioned that IPV screening may be offensive to those who are abused, whereas those who reported abuse thought IPV screening was essential “to stop it [from] happening.” Our findings challenge concerns that IPV screening is offensive to women and increases their potential for danger. Participants were appreciative of the opportunity to tell their abuse stories in a safe and supportive context, and challenged the health care system to implement IPV screening, asking “What took you so long?” 相似文献
34.
Richard A. Oram Seth A. Sharp Catherine Pihoker Lauric Ferrat Giuseppina Imperatore Adrienne Williams Maria J. Redondo Lynne Wagenknecht Lawrence M. Dolan Jean M. Lawrence Michael N. Weedon Ralph DAgostino Jr. William A. Hagopian Jasmin Divers Dana Dabelea 《Diabetes care》2022,45(5):1124
OBJECTIVEGenetic risk scores (GRS) aid classification of diabetes type in White European adult populations. We aimed to assess the utility of GRS in the classification of diabetes type among racially/ethnically diverse youth in the U.S.RESEARCH DESIGN AND METHODSWe generated type 1 diabetes (T1D)- and type 2 diabetes (T2D)-specific GRS in 2,045 individuals from the SEARCH for Diabetes in Youth study. We assessed the distribution of genetic risk stratified by diabetes autoantibody positive or negative (DAA+/−) and insulin sensitivity (IS) or insulin resistance (IR) and self-reported race/ethnicity (White, Black, Hispanic, and other).RESULTST1D and T2D GRS were strong independent predictors of etiologic type. The T1D GRS was highest in the DAA+/IS group and lowest in the DAA−/IR group, with the inverse relationship observed with the T2D GRS. Discrimination was similar across all racial/ethnic groups but showed differences in score distribution. Clustering by combined genetic risk showed DAA+/IR and DAA−/IS individuals had a greater probability of T1D than T2D. In DAA− individuals, genetic probability of T1D identified individuals most likely to progress to absolute insulin deficiency.CONCLUSIONSDiabetes type–specific GRS are consistent predictors of diabetes type across racial/ethnic groups in a U.S. youth cohort, but future work needs to account for differences in GRS distribution by ancestry. T1D and T2D GRS may have particular utility for classification of DAA− children. 相似文献
35.
36.
The determinants that underlie a healthy or unhealthy pregnancy are complex and not well understood. We assess the relationship between the built environment and maternal psychosocial status using directly observed residential neighborhood characteristics (housing damage, property disorder, tenure status, vacancy, security measures, violent crime, and nuisances) and a wide range of psychosocial attributes (interpersonal support evaluation list, self-efficacy, John Henryism active coping, negative partner support, Perceived Stress Scale, perceived racism, Center for Epidemiologic Studies—Depression) on a pregnant cohort of women living in the urban core of Durham, NC, USA. We found some associations between built environment characteristic and psychosocial health varied by exposure categorization approach, while others (residence in environments with more rental property is associated with higher reported active coping and negative partner support) were consistent across exposure categorizations. This study outlines specific neighborhood characteristics that are modifiable risk markers and therefore important targets for increased research and public health intervention. 相似文献
37.
38.
The Rosenberg Self-Esteem (RSE) Scale is a commonly used measure of global self-esteem, an important element of mental health. The purpose of this cross sectional secondary analysis was to examine the psychometric properties of the scale in a sample of 98 African American single mothers. The RSE Scale showed adequate internal consistency with an alpha coefficient of .83. Two factors that accounted for a total of 54.7% of the variance were extracted. Self-esteem showed a strong negative relationship with both depressive symptoms and negative thinking. This study provides support for the internal consistency of the RSE Scale and partial support for its construct validity in this population. The RSE appears to represent a bidimensional construct of self-esteem for African American women, with the cultural influences of racial esteem and the rejection of negative stereotypes forming a separate and distinct aspect of this concept. The RSE Scale should be used and interpreted with caution in this population given these findings. 相似文献
39.
Microgravity culture condition reduces immunogenicity and improves function of pancreatic islets1 总被引:3,自引:0,他引:3
BACKGROUND: The failure of pancreatic islet allotransplants observed in almost all clinical attempts is related to poor initial islet function and allograft rejection. To remedy these problems we cultured islets in microgravity conditions to improve their function and to reduce their immunogenicity. METHODS: Fresh mouse islets or mouse islets cultured in stationary dishes or microgravity bioreactors were transplanted to streptozotocin-induced diabetic mouse recipients. RESULTS: Both allogeneic dish- or bioreactor-cultured islets survived more than 100 days compared with fresh allogeneic islets, which were rejected in less than 15 days. Islet titration studies revealed that 250 fresh or dish-cultured, but only 30 to 120 bioreactor-cultured, islets were necessary to produce euglycemia. Furthermore, glucose tolerance tests showed that bioreactor-cultured islets functioned better compared with fresh and dish-cultured islets on day 30 postgrafting. Immunostaining and transmission electron microscopy (TEM) analyses showed the gradual disappearance of dendritic cells in cultured islets compared with fresh islets. TEM revealed that the ultrastructure of islets from bioreactor, but not dish, appeared healthy and closely resembled fresh islets. Interestingly, TEM and scanning electron microscopy showed that only bioreactor-cultured islets developed unique and multiple nutritional channels between arrays of islet cells. TEM with colloidal lanthanum tracer revealed that only bioreactor islet cell cultures were devoid of tight junctional complexes, which may facilitate channel formation. CONCLUSION: Microgravity condition decreases immunogenicity and significantly improves the function of secretory cells. 相似文献
40.
Varus and valgus flexion laxity of total knee alignment methods in loaded cadaveric knees. 总被引:2,自引:0,他引:2
José Romero James F Duronio Afshin Sohrabi Nicolas Alexander Bruce A MacWilliams Lynne C Jones David S Hungerford 《Clinical orthopaedics and related research》2002,(394):243-253
Both total knee alignment methods, the anatomic and classic, seek to achieve stability in flexion and extension. However, posterior femoral condyle referencing (anatomic alignment) combined with perpendicular tibial resection (classic alignment) results in a 3 degree relative internal rotation of the femoral component with lateral joint opening. The current cadaver study investigated the influence of total knee alignment methods and femoral component malrotation (3 degrees and 6 degrees internal and external malrotation) on femorotibial laxity. Varus and valgus excursion tests were done at 0 degrees, 30 degrees, 60 degrees, and 90 degrees knee flexion under vertical loading conditions of 150 N. None of the alignments produced increased laxity in extension. The largest laxity was found on the varus test at 60 degrees flexion with the femoral component at 6 degrees internal rotation. A 3 degree internal rotation of the femoral component showed increased varus laxity only for the combined alignment method. This finding shows that the femoral component position of the combined alignment method is a 3 degree relative internal malrotation and that an additional internal malrotation may compromise varus stability. Posterior femoral condyle referencing did not provide proper femoral component rotation. A ligament tensor may be helpful in determining femoral component rotation after soft tissue release in extension is performed. 相似文献