全文获取类型
收费全文 | 47553篇 |
免费 | 4481篇 |
国内免费 | 74篇 |
学科分类
医药卫生 | 52108篇 |
出版年
2021年 | 651篇 |
2019年 | 641篇 |
2018年 | 757篇 |
2017年 | 635篇 |
2016年 | 616篇 |
2015年 | 710篇 |
2014年 | 960篇 |
2013年 | 1507篇 |
2012年 | 2174篇 |
2011年 | 2250篇 |
2010年 | 1227篇 |
2009年 | 1012篇 |
2008年 | 1890篇 |
2007年 | 2056篇 |
2006年 | 2016篇 |
2005年 | 2010篇 |
2004年 | 1825篇 |
2003年 | 1667篇 |
2002年 | 1702篇 |
2001年 | 1605篇 |
2000年 | 1708篇 |
1999年 | 1449篇 |
1998年 | 672篇 |
1997年 | 534篇 |
1996年 | 529篇 |
1995年 | 531篇 |
1994年 | 450篇 |
1993年 | 458篇 |
1992年 | 1257篇 |
1991年 | 1165篇 |
1990年 | 1149篇 |
1989年 | 1083篇 |
1988年 | 1003篇 |
1987年 | 1005篇 |
1986年 | 920篇 |
1985年 | 924篇 |
1984年 | 715篇 |
1983年 | 630篇 |
1982年 | 444篇 |
1981年 | 392篇 |
1980年 | 407篇 |
1979年 | 656篇 |
1978年 | 524篇 |
1977年 | 407篇 |
1976年 | 403篇 |
1975年 | 376篇 |
1974年 | 450篇 |
1973年 | 437篇 |
1972年 | 450篇 |
1971年 | 422篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
A number of vitamin D3 metabolites inhibit benzodiazepine- and dimethyl sulfoxide-induced differentiation of Friend erythroleukemia cells. The inhibition is dose dependent and occurs at nM concentrations. The order of potency of these compounds is 1,25-dihydroxycholecalciferol greater than 1,25,26-trihydroxycholecalciferol greater than 1,24R,25-trihydroxycholecalciferol greater than 1 alpha-hydroxycholecalciferol greater than 24R,25-dihydroxycholecalciferol greater than 25S,26-dihydroxycholecalciferol. The inhibition is maximal when the vitamin D3 analogs are added together with the inducer, and becomes progressively decreased with delayed addition. These results suggest that the vitamin D3 metabolites may play a regulatory role in erythropoiesis. 相似文献
53.
54.
55.
Sanjay Sisodiya J Helen Cross Ingmar Blümcke David Chadwick John Craig Peter B Crino Paul Debenham Norman Delanty Frances Elmslie Mark Gardiner Jeffrey Golden David Goldstein David A Greenberg Renzo Guerrini Michael Hanna John Harris Paul Harrison Michael R Johnson George Kirov Dimitri M Kullman Andrew Makoff Carla Marini Rima Nabbout Lina Nashef Jeffrey L Noebels Ruth Ottman Munir Pirmohamed Asla Pitk?nen Ingrid Scheffer Simon Shorvon Graeme Sills Nicholas Wood Sameer Zuberi 《Epileptic Disord》2007,9(2):194-236
The Sixth Epilepsy Research Foundation workshop, held in Oxford in March 2006, brought together basic scientists, geneticists, epidemiologists, statisticians, pharmacologists and clinicians to consider progress, issues and strategies for harnessing genetics to improve the understanding and treatment of the epilepsies. General principles were considered, including the fundamental importance of clear study design, adequate patient numbers, defi ned phenotypes, robust statistical data handling, and follow-up of genetic discoveries. Topics where some progress had been made were considered including chromosomal abnormalities, neurodevelopment, hippocampal sclerosis, juvenile myoclonic epilepsy, focal cortical dysplasia and pharmacogenetics. The ethical aspects of epilepsy genetics were reviewed. Principles and limitations of collaboration were discussed. Presentations and their matched discussions are produced here. There was optimism that further genetic research in epilepsy was not only feasible, but might lead to improvements in the lives of people with epilepsy. 相似文献
56.
Greg Guest Laura Johnson Holly Burke Reathe Rain-Taljaard Lawrence Severy Claire von Mollendorf Lut Van Damme 《AIDS education and prevention》2007,19(4):310-320
If proven effective, vaginal microbicides and diaphragms will likely be part of a larger HIV prevention model that includes condoms and other prevention strategies. It is, therefore, important to understand how introducing new prevention methods may affect overall patterns of sexual risk behavior. Data presented were collected as part of a safety and feasibility study of ACIDFORM gel with a diaphragm among 120 women in South Africa. Interviews were administered at enrollment and months 1, 3, 5, and 6 of the trial. Focus groups were conducted at trial exit. Frequency of sex increased significantly after enrollment. This increase appears to be owing to perceived protection from HIV and greater sexual pleasure afforded by the gel. Male condom use was high overall but increased significantly from enrollment. Data suggest this is because of increased partner involvement, increased negotiating power afforded by study participation, and provision of free condoms perceived to be of high quality. 相似文献
57.
R D Alarcon B R Johnson J P Lucas 《Journal of the American Academy of Child and Adolescent Psychiatry》1991,30(6):999-1002
Obsessive-compulsive disorder is increasingly recognized in patients of different age groups. Serotonergic agents, such as clomipramine, have been recently found to be useful in the management of this condition. However, unexpected side effects, such as dysphoria, aggressiveness, and paranoid ideation, may occur with therapeutic doses of this compound, as evidenced in the cases of two male adolescents presented here. Possible pathogenetic factors, involving serotonin and serotonin-receptor abnormalities are discussed. Management of these side effects is based on adequate dose reduction and monitorization. 相似文献
58.
59.
J.D. Schold T.R. Srinivas G. Guerra A.I. Reed R.J. Johnson I.D. Weiner R. Oberbauer J.S. Harman A.W. Hemming H.U. Meier-Kriesche 《American journal of transplantation》2007,7(3):550-559
Research suggests that end-stage renal disease patients with elevated body mass index (BMI) have superior outcomes on dialysis. In contrast, low and high BMI patients represent the highest risk cohorts for kidney transplant recipients. The important question remains concerning how to manage transplant candidates given the potentially incommensurate impact of BMI by treatment modality. We conducted a retrospective analysis of waitlisted and transplanted patients in the United States from 1990 to 2003. We constructed Cox models to evaluate the effect of BMI on mortality of waitlisted candidates and identified risk factors for rapid weight change. We then assessed the impact of weight change during waitlisting on transplant outcomes. Decline in BMI on the waiting list was not protective for posttransplant mortality or graft loss across BMI strata. Substantial weight loss pretransplantation was associated with rapid gain posttransplantation. The highest risk for death was among listed patients with low BMI (13-20 kg/m(2), adjusted hazard ratio = 1.47, p < 0.01). Approximately one-third of candidates had a change in BMI category prior to transplantation. While observed declines in BMI may be volitional or markers of disease processes, there is no evidence that candidates have improved transplant outcomes attributable to weight loss. Prospective trials are needed to evaluate the efficacy of weight loss protocols for candidates of kidney transplantation. 相似文献
60.
Ruth W Johnson Joan S Tilghman Lorrie R Davis-Dick Barbara Hamilton-Faison 《The ABNF journal》2006,17(2):60-62
The following article is an attempt to encapsulate an historical overview of spirituality in nursing. Despite a plethora of information relative to spirituality in nursing, the decision was to do an eclectic overview that was not reflective of any one spiritual/religious group. The authors at times found this goal difficult when writing about the Pre-Christian and Christian eras. Most of the major religions have their own perspective on the concept of spirituality, and historical personalities recorded maybe reflective of that particular religion. Another factor that impacted on the writing of this article was the concept that spirituality was not always linked specifically to religion. Spirituality was an experiential component of the wonders of nature and life, a domain that the authors took into account but did not expound upon. Finally the authors realized that spirituality has almost always been an aspect of African-American life and certainly of those in nursing. To this end the authors realize that there is a need for more research in this area. 相似文献