全文获取类型
收费全文 | 5429篇 |
免费 | 550篇 |
国内免费 | 4篇 |
出版年
2023年 | 47篇 |
2022年 | 101篇 |
2021年 | 183篇 |
2020年 | 117篇 |
2019年 | 121篇 |
2018年 | 141篇 |
2017年 | 132篇 |
2016年 | 186篇 |
2015年 | 308篇 |
2014年 | 322篇 |
2013年 | 318篇 |
2012年 | 470篇 |
2011年 | 455篇 |
2010年 | 238篇 |
2009年 | 228篇 |
2008年 | 318篇 |
2007年 | 280篇 |
2006年 | 266篇 |
2005年 | 236篇 |
2004年 | 214篇 |
2003年 | 171篇 |
2002年 | 141篇 |
2001年 | 58篇 |
2000年 | 49篇 |
1999年 | 39篇 |
1998年 | 43篇 |
1997年 | 34篇 |
1996年 | 27篇 |
1995年 | 23篇 |
1994年 | 27篇 |
1993年 | 25篇 |
1992年 | 38篇 |
1991年 | 31篇 |
1990年 | 26篇 |
1989年 | 38篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 28篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 17篇 |
1979年 | 37篇 |
1978年 | 22篇 |
1977年 | 23篇 |
1976年 | 25篇 |
1975年 | 19篇 |
1974年 | 22篇 |
排序方式: 共有5983条查询结果,搜索用时 15 毫秒
1.
2.
This study aimed to identify influences, attitudes and actions of nursing staff in relation to oral care for people with disabilities. Individual in-depth interviews of twenty two nursing staff were conducted. Enabling and inhibiting factors in the reported attitudes, approaches and practices were identified. The main enabling factors were that nursing staff saw mouth care as part of their role and took an empathic and caring approach to its delivery. They aimed to make the residents socially acceptable, improve their self-esteem and make their mouths clean and breath fresher. Inhibiting factors were: a lack of training, time constraints associated with workload, and poor understanding of the processes causing dental disease. The study concludes that improvements in oral care by nursing staff can be encouraged by working with nurses'attitudes, values and beliefs. Once the desired behaviour change has occurred then the lack of knowledge can be addressed. 相似文献
3.
4.
Emily Olfson Catherine E. Cottrell Nicholas O. Davidson Christina A. Gurnett Jonathan W. Heusel Nathan O. Stitziel Li-Shiun Chen Sarah Hartz Rakesh Nagarajan Nancy L. Saccone Laura J. Bierut 《PloS one》2015,10(9)
The American College of Medical Genetics and Genomics (ACMG) recommends that clinical sequencing laboratories return secondary findings in 56 genes associated with medically actionable conditions. Our goal was to apply a systematic, stringent approach consistent with clinical standards to estimate the prevalence of pathogenic variants associated with such conditions using a diverse sequencing reference sample. Candidate variants in the 56 ACMG genes were selected from Phase 1 of the 1000 Genomes dataset, which contains sequencing information on 1,092 unrelated individuals from across the world. These variants were filtered using the Human Gene Mutation Database (HGMD) Professional version and defined parameters, appraised through literature review, and examined by a clinical laboratory specialist and expert physician. Over 70,000 genetic variants were extracted from the 56 genes, and filtering identified 237 variants annotated as disease causing by HGMD Professional. Literature review and expert evaluation determined that 7 of these variants were pathogenic or likely pathogenic. Furthermore, 5 additional truncating variants not listed as disease causing in HGMD Professional were identified as likely pathogenic. These 12 secondary findings are associated with diseases that could inform medical follow-up, including cancer predisposition syndromes, cardiac conditions, and familial hypercholesterolemia. The majority of the identified medically actionable findings were in individuals from the European (5/379) and Americas (4/181) ancestry groups, with fewer findings in Asian (2/286) and African (1/246) ancestry groups. Our results suggest that medically relevant secondary findings can be identified in approximately 1% (12/1092) of individuals in a diverse reference sample. As clinical sequencing laboratories continue to implement the ACMG recommendations, our results highlight that at least a small number of potentially important secondary findings can be selected for return. Our results also confirm that understudied populations will not reap proportionate benefits of genomic medicine, highlighting the need for continued research efforts on genetic diseases in these populations. 相似文献
5.
6.
Ernest I. Onyishi Piotr Sorokowski Agnieszka Sorokowska R. Nathan Pipitone 《Evolution and human behavior》2012,33(6):771-774
Previous research has demonstrated that having more children decreases marital satisfaction among parents. However, the universality of these findings is limited since the vast majority of the studies have been conducted in Western countries. In the present study, 374 people from the Igbo ethnic group (Nigeria) were assessed for levels of marital satisfaction and the number of children. In contrast to almost all previous findings, we found a positive relationship between the number of children and marital satisfaction among parents. Number of children was the strongest predictor of marital satisfaction even when compared to other variables like wealth and education. Our results suggest that the negative relationship between the number of children and marital satisfaction is not culturally universal and probably only characterizes developed, individualistic Western countries. We discuss our findings from a sociocultural and evolutionary perspective. 相似文献
7.
8.
9.
Eva Decru Nathan Vranken Pedro H. N. Bragança Jos Snoeks Maarten Van Steenberge 《Journal of fish biology》2020,96(5):1186-1201
Based on literature, museum collections and three recent expeditions, an annotated species list of the Lake Edward, East Africa, drainage system is presented, excluding the endemic haplochromines. A total of 34 non-Haplochromis species belonging to 10 families and 21 genera are recorded from the system. Three of these are endemic and two others have been introduced in the region. Six species are new records for the Lake Edward system. A species accumulation curve indicates that we probably covered most of the non-Haplochromis species in the area sampled during the recent expeditions, but undetected species might still be present in the Congolese part of the system, which is poorly sampled. A comparison of the species list with those of neighbouring basins confirmed the placement of the Lake Edward system within the east-coast ichthyofaunal province. 相似文献
10.
At present there is little knowledge about how density regulates population growth rate and to what extent this is determined by life-history patterns. We compared density dependent population consequences in the Nicholsonian sense based on experimental observations and life-history modeling for the earthworms Lumbricus terrestris and Eisenia fetida . Both species differ in their life-histories, L. terrestris being a relatively long-lived species with slow reproduction and occurring at low densities compared to E. fetida which has a more opportunistic strategy with a high reproductive output. E. fetida is able to colonise new habitats rapidly and may occur at relatively high population densities. Density dependency of population growth rate was estimated by incorporating density dependent effects on reproduction and growth using a modified Euler equation. The results point out that E. fetida was not as strongly impacted by density as compared to L. terrestris . Population growth rate in E. fetida was hardly affected at low and moderate density, being reduced only at high level, this compares to L. terrestris where even relatively small density effects resulted in a strong negative effect on population growth rate. Our findings indicate that density-dependent regulation in earthworms can be quantified using life-history analysis. The outcomes are in agreement with empirical field observations for populations (i.e. L. terrestris occurs ar low density, E. fetida at high density). Consideration of the potential importance of Nicholsonian density dependence for field populations of these two species in light of their known biology however produces counterintuitive conclusions. In E. fetida , although density tolerant, rapid population growth may mean this species may be subject to density dependeny regulation. In L. terrestris , although density sensitive, complex behavioural ecology (surface activity, territoriality) may limit of feedback influence on population size. 相似文献