全文获取类型
收费全文 | 2767篇 |
免费 | 184篇 |
国内免费 | 1篇 |
专业分类
2952篇 |
出版年
2023年 | 16篇 |
2022年 | 36篇 |
2021年 | 39篇 |
2020年 | 39篇 |
2019年 | 36篇 |
2018年 | 52篇 |
2017年 | 53篇 |
2016年 | 95篇 |
2015年 | 141篇 |
2014年 | 176篇 |
2013年 | 208篇 |
2012年 | 257篇 |
2011年 | 228篇 |
2010年 | 131篇 |
2009年 | 108篇 |
2008年 | 162篇 |
2007年 | 154篇 |
2006年 | 141篇 |
2005年 | 140篇 |
2004年 | 137篇 |
2003年 | 126篇 |
2002年 | 86篇 |
2001年 | 27篇 |
2000年 | 11篇 |
1999年 | 29篇 |
1998年 | 32篇 |
1997年 | 29篇 |
1996年 | 29篇 |
1995年 | 15篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 3篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 9篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 3篇 |
排序方式: 共有2952条查询结果,搜索用时 0 毫秒
31.
32.
33.
Beth Rachlis Violet Naanyu Juddy Wachira Becky Genberg Beatrice Koech Regina Kamene Jackie Akinyi Paula Braitstein 《PloS one》2016,11(2)
Given shortages of health care providers and a rise in the number of people living with both communicable and non-communicable diseases, Community Health Workers (CHWs) are increasingly incorporated into health care programs. We sought to explore community perceptions of CHWs including perceptions of their roles in chronic disease management as part of the Academic Model Providing Access to Healthcare Program (AMPATH) in western Kenya. In depth interviews and focus group discussions were conducted between July 2012 and August 2013. Study participants were purposively sampled from three AMPATH sites: Chulaimbo, Teso and Turbo, and included patients within the AMPATH program receiving HIV, tuberculosis (TB), and hypertension (HTN) care, as well as caregivers of children with HIV, community leaders, and health care workers. Participants were asked to describe their perceptions of AMPATH CHWs, including identifying the various roles they play in engagement in care for chronic diseases including HIV, TB and HTN. Data was coded and various themes were identified. We organized the concepts and themes generated using the Andersen-Newman Framework of Health Services Utilization and considering CHWs as a potential enabling resource. A total of 207 participants including 110 individuals living with HIV (n = 50), TB (n = 39), or HTN (n = 21); 24 caregivers; 10 community leaders; and 34 healthcare providers participated. Participants identified several roles for CHWs including promoting primary care, encouraging testing, providing education and facilitating engagement in care. While various facilitating aspects of CHWs were uncovered, several barriers of CHW care were raised, including issues with training and confidentiality. Suggested resources to help CHWs improve their services were also described. Our findings suggest that CHWs can act as catalysts and role models by empowering members of their communities with increased knowledge and support. 相似文献
34.
35.
Kátia Regina da Silva Roberto Costa Elizabeth Sartori Crevelari Marianna Sobral Lacerda Caio Marcos de Moraes Albertini Martino Martinelli Filho José Eduardo Santana Jo?o Ricardo Nickenig Vissoci Ricardo Pietrobon Jacson V. Barros 《PloS one》2013,8(7)
Background
The ability to apply standard and interoperable solutions for implementing and managing medical registries as well as aggregate, reproduce, and access data sets from legacy formats and platforms to advanced standard formats and operating systems are crucial for both clinical healthcare and biomedical research settings.Purpose
Our study describes a reproducible, highly scalable, standard framework for a device registry implementation addressing both local data quality components and global linking problems.Methods and Results
We developed a device registry framework involving the following steps: (1) Data standards definition and representation of the research workflow, (2) Development of electronic case report forms using REDCap (Research Electronic Data Capture), (3) Data collection according to the clinical research workflow and, (4) Data augmentation by enriching the registry database with local electronic health records, governmental database and linked open data collections, (5) Data quality control and (6) Data dissemination through the registry Web site. Our registry adopted all applicable standardized data elements proposed by American College Cardiology / American Heart Association Clinical Data Standards, as well as variables derived from cardiac devices randomized trials and Clinical Data Interchange Standards Consortium. Local interoperability was performed between REDCap and data derived from Electronic Health Record system. The original data set was also augmented by incorporating the reimbursed values paid by the Brazilian government during a hospitalization for pacemaker implantation. By linking our registry to the open data collection repository Linked Clinical Trials (LinkedCT) we found 130 clinical trials which are potentially correlated with our pacemaker registry.Conclusion
This study demonstrates how standard and reproducible solutions can be applied in the implementation of medical registries to constitute a re-usable framework. Such approach has the potential to facilitate data integration between healthcare and research settings, also being a useful framework to be used in other biomedical registries. 相似文献36.
Sarvpreet Singh Frank R. Kloss Regina Brunauer Magdalena Schimke Angelika Jamnig Brigitte Greiderer‐Kleinlercher Günter Klima Julia Rentenberger Thomas Auberger Oliver Hächl Michael Rasse Robert Gassner Günter Lepperdinger 《Journal of cellular and molecular medicine》2012,16(4):877-887
Irradiation impacts on the viability and differentiation capacity of tissue‐borne mesenchymal stem cells (MSC), which play a pivotal role in bone regeneration. As a consequence of radiotherapy, bones may develop osteoradionecrosis. When irradiating human bone‐derived MSC in vitro with increasing doses, the cells’ self‐renewal capabilities were greatly reduced. Mitotically stalled cells were still capable of differentiating into osteoblasts and pre‐adipocytes. As a large animal model comparable to the clinical situation, pig mandibles were subjected to fractionized radiation of 2 χ 9 Gy within 1 week. This treatment mimics that of a standardized clinical treatment regimen of head and neck cancer patients irradiated 30 χ 2 Gy. In the pig model, fractures which had been irradiated, showed delayed osseous healing. When isolating MSC at different time points post‐irradiation, no significant changes regarding proliferation capacity and osteogenic differentiation potential became apparent. Therefore, pig mandibles were irradiated with a single dose of either 9 or 18 Gy in vivo, and MSC were isolated immediately afterwards. No significant differences between the untreated and 9 Gy irradiated bone with respect to proliferation and osteogenic differentiation were unveiled. Yet, cells isolated from 18 Gy irradiated specimens exhibited a reduced osteogenic differentiation capacity, and during the first 2 weeks proliferation rates were greatly diminished. Thereafter, cells recovered and showed normal proliferation behaviour. These findings imply that MSC can effectively cope with irradiation up to high doses in vivo. This finding should thus be implemented in future therapeutic concepts to protect regenerating tissue from radiation consequences. 相似文献
37.
Anna CC Aguiar Ananda C Cunha Isabela Penna Ceravolo Regina A Correia Gon?alves Arildo JB Oliveira Antoniana Ursine Krettli 《Memórias do Instituto Oswaldo Cruz》2015,110(7):906-913
Several species of Aspidosperma plants are used to treat diseases in
the tropics, including Aspidosperma ramiflorum, which acts against
leishmaniasis, an activity that is experimentally confirmed. The species, known as
guatambu-yellow, yellow peroba,
coffee-peroba andmatiambu, grows in the Atlantic
Forest of Brazil in the South to the Southeast regions. Through a guided
biofractionation of A. ramiflorum extracts, the plant activity
against Plasmodium falciparum was evaluated in vitro for toxicity
towards human hepatoma G2 cells, normal monkey kidney cells and nonimmortalised human
monocytes isolated from peripheral blood. Six of the seven extracts tested were
active at low doses (half-maximal drug inhibitory concentration < 3.8 µg/mL); the
aqueous extract was inactive. Overall, the plant extracts and the purified compounds
displayed low toxicity in vitro. A nonsoluble extract fraction and one purified
alkaloid isositsirikine (compound 5) displayed high selectivity indexes (SI) (= 56
and 113, respectively), whereas compounds 2 and 3 were toxic (SI < 10). The
structure, activity and low toxicity of isositsirikine in vitro are described here
for the first time in A. ramiflorum, but only the neutral and
precipitate plant fractions were tested for activity, which caused up to 53%
parasitaemia inhibition of Plasmodium berghei in mice with
blood-induced malaria. This plant species is likely to be useful in the further
development of an antimalarial drug, but its pharmacological evaluation is still
required. 相似文献
38.
Transcriptional regulation of vascular bone morphogenetic protein by endothelin receptors in early autoimmune diabetes mellitus 总被引:2,自引:0,他引:2
Nett PC Ortmann J Celeiro J Haas E Hofmann-Lehmann R Tornillo L Terraciano LM Barton M 《Life sciences》2006,78(19):2213-2218
Endothelin (ET) and bone morphogenic proteins (BMP) have been implicated in the development of micro- and macrovascular complications of type 2 diabetes mellitus due to atherosclerosis. This study investigated vascular BMP-expression during early development of experimental autoimmune diabetes mellitus and whether ET(A) receptors are involved in its regulation, using the selective ET(A) receptor antagonist BSF461314. Specificity of BSF461314 was confirmed through ET-mediated p44/42 mitogen-activated protein kinase (ERK1/2) phosphorylation experiments. For animal studies, non-obese diabetic (NOD) and control mice at 16 weeks of age were treated with BSF461314 for 6 weeks. Plasma glucose levels were measured before and after treatment and vascular gene expression of BMP-2, BMP-7, and BMP-type II receptor was determined in the aorta by quantitative real-time polymerase chain reaction analysis. At the beginning of the study in all animals, plasma glucose levels were within the normal range. After 6 weeks gene expression of vascular BMP-2, BMP-7 and BMP-type II receptor was almost doubled in NOD mice compared with non-diabetic controls (p < 0.05). Concomitant treatment with BSF461314 significantly reduced expression of all BMPs and lowered plasma glucose levels in NOD mice close to controls (all p < 0.05 versus untreated). In conclusion, vascular BMP-2, BMP-7, and BMP-type II receptor expression is upregulated in early stages of autoimmune diabetes mellitus. The data further indicate that ET(A) receptors inhibit diabetes-associated activation of vascular BMPs and regulate plasma glucose levels suggesting that ET(A) receptors might provide a new therapeutic target to interfere with the early development of atherosclerosis in patients with type 1 diabetes mellitus. 相似文献
39.
Fuster A Picó C Sánchez J Oliver P Zingaretti MC Murano I Morroni M Hoeller U Goralczyk R Cinti S Palou A 《The Journal of nutritional biochemistry》2008,19(5):295-304
Epidemiological studies have demonstrated that people who eat more fruits and vegetables (rich in carotenoids) and people who have higher serum beta-carotene (BC) levels have a lower risk of cancer, particularly lung cancer. However, the two main human intervention studies of BC supplementation (the ATBC and the CARET trials) revealed an increased risk of lung cancer among smokers and asbestos workers. Previous studies carried out in the ferret have reported that BC effects are related to dose. Here, we treated ferrets with two concentrations of oral BC (0.8 and 3.2 mg/kg body weight per day) for 6 months, using BC in a formulation also containing dl-alpha-tocopherol and ascorbyl palmitate. The effect of the smoke-derived carcinogenic agent benzo[a]pyrene (BP), with or without low-dose BC, was also analysed. We determined the protein levels and mRNA expression levels of activator protein 1 (c-Jun and c-Fos), c-Myc, cyclin D1, proliferating cellular nuclear antigen and retinoic acid receptor beta. We did not find higher levels of cell proliferation markers in the lung of ferrets treated with BC or signals of squamous metaplasia lesions either. On the other hand, although no evident signals of pulmonary carcinogenesis were observed in animals exposed to BP, BC supplementation in these animals may prevent against excess cell proliferation, since this reestablishes Jun protein and cyclin D1 mRNA levels in the lung of BP-exposed animals. In summary, these results show that the combination of BC with alpha-tocopherol and ascorbyl palmitate does not induce pro-oxidant effects in the lung of ferrets. 相似文献
40.
Sergio Luiz Montego Ferreira Junior Elis Regina Dalla Costa Paula Gon?alves dos Santos Harrison Magdinier Gomes Marcia Susana Nunes Silva Leonardo Souza Esteves Martha Maria Oliveira Raquel de Abreu Maschmann Afranio Lineu Kritski Philip Noel Suffys Maria Lucia Rosa Rossetti 《Memórias do Instituto Oswaldo Cruz》2014,109(3):307-314
Drug-resistant tuberculosis (TB) threatens global TB control and is a major public
health concern in several countries. We therefore developed a multiplex assay
(LINE-TB/MDR) that is able to identify the most frequent mutations related to
rifampicin (RMP) and isoniazid (INH) resistance. The assay is based on multiplex
polymerase chain reaction, membrane hybridisation and colorimetric detection
targeting of rpoB and katG genes, as well as the
inhA promoter, which are all known to carry specific mutations
associated with multidrug-resistant TB (MDR-TB). The assay was validated on a
reference panel of 108 M. tuberculosis isolates that were characterised by the
proportion method and by DNA sequencing of the targets. When comparing the
performance of LINE-TB/MDR with DNA sequencing, the sensitivity, specificity and
agreement were 100%, 100% and 100%, respectively, for RMP and 77.6%, 90.6% and 88.9%,
respectively, for INH. Using drug sensibility testing as a reference standard, the
performance of LINE-TB/MDR regarding sensitivity, specificity and agreement was 100%,
100% and 100% (95%), respectively, for RMP and 77%, 100% and 88.7% (82.2-95.1),
respectively, for INH. LINE-TB/MDR was compared with GenoType MTBDRplus for 65
isolates, resulting in an agreement of 93.6% (86.7-97.5) for RIF and 87.4%
(84.3-96.2) for INH. LINE-TB/MDR warrants further clinical validation and may be an
affordable alternative for MDR-TB diagnosis. 相似文献