全文获取类型
收费全文 | 4708篇 |
免费 | 202篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 172篇 |
儿科学 | 218篇 |
妇产科学 | 208篇 |
基础医学 | 670篇 |
口腔科学 | 43篇 |
临床医学 | 286篇 |
内科学 | 1115篇 |
皮肤病学 | 63篇 |
神经病学 | 435篇 |
特种医学 | 95篇 |
外科学 | 286篇 |
综合类 | 34篇 |
一般理论 | 1篇 |
预防医学 | 395篇 |
眼科学 | 86篇 |
药学 | 564篇 |
中国医学 | 12篇 |
肿瘤学 | 247篇 |
出版年
2024年 | 6篇 |
2023年 | 39篇 |
2022年 | 245篇 |
2021年 | 364篇 |
2020年 | 128篇 |
2019年 | 142篇 |
2018年 | 178篇 |
2017年 | 140篇 |
2016年 | 143篇 |
2015年 | 181篇 |
2014年 | 206篇 |
2013年 | 257篇 |
2012年 | 402篇 |
2011年 | 436篇 |
2010年 | 195篇 |
2009年 | 131篇 |
2008年 | 259篇 |
2007年 | 293篇 |
2006年 | 265篇 |
2005年 | 261篇 |
2004年 | 249篇 |
2003年 | 211篇 |
2002年 | 136篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 2篇 |
排序方式: 共有4930条查询结果,搜索用时 12 毫秒
81.
82.
ObjectiveThe objective of the study was to assess dental and periodontal status in relation to bone mineral density (BMD), and to study cytological changes in oral epithelium.MethodsThirty-seven postmenopausal women aged 50–70 were given a dental examination and a BMD assessment.ResultsThere was a relationship between the femoral neck BMD and teeth state, a negative correlation between the lumbar BMD and the periodontal disease index (PDI) and between the radius BMD and the papillary bleeding index (PBI). PDI correlated positively with the number of superficial cells in the marginal gingiva smears. Correlation between PDI and parabasal cells and the number of teeth was negative.ConclusionsIn observed postmenopausal women, there is a negative association between bone mineral density and teeth state and periodontal indices. Oral epithelium revealed atrophic changes resulting in low keratinization. The study suggests an association between decreasing in bone mineral density, alveolar bone loss and the numbers of various cell types in epithelial smears. 相似文献
83.
Katarzyna Matusiak Agnieszka Skoczen Zuzanna Setkowicz Aldona Kubala-Kukus Ilona Stabrawa Małgorzata Ciarach 《Nanotoxicology》2017,11(9-10):1225-1236
The main goal of this study was to evaluate in vivo effects of low dose of PEG-coated magnetic iron oxide nanoparticles (IONPs) on the rat liver. The IONPs was intravenously injected into rats at a dose equaled to 0.03?mg of Fe per 1?kg of an animal body weight. The elemental composition of liver tissue in rats subjected to IONPs action and controls were compared. Moreover, in order to determine the dynamics of nanoparticles (NPs) induced elemental changes, the tissues taken from animals 2?hours, 24?hours, and 7?days from IONPs injection were examined. The analysis of subtle elemental anomalies occurring as a result of IONPs action required application of highly sensitive analytical method. The total reflection X-ray fluorescence spectroscopy perfectly meets such requirements and therefore it was used in this study. The obtained results showed increasing trend of Fe level within liver occurring 2?hours from IONPs injection. One day after NPs administration, the liver Fe content presented the baseline level what suggests only the short-term accumulation of nanoparticles in the organ. The Ca, Cu, and Zn levels changed significantly as a result of NPs action. Moreover, the anomalies in their accumulation were still observed 7?days after IONPs injection. The level of Cu decreased while those of Ca and Zn increased in the liver of NPs-treated animals. The reduced liver Cu, followed by elevated serum level of this element, might be related in triggering the mechanisms responsible for Fe metabolism in the organism. 相似文献
84.
Balloon Dilatation for Removal of an Irretrievable Permanent Hemodialysis Catheter: The Safest Approach 下载免费PDF全文
Krzysztof Letachowicz Mariusz Kusztal Maciej Szymczak Katarzyna Madziarska Katarzyna Jakuszko Sławomir Zmonarski Maciej Guziński Wacław Weyde Marian Klinger 《Artificial organs》2016,40(5):E84-E88
Long‐term hemodialysis catheter dwell time in the central vein predisposes to fibrin sheath development, which subsequently causes catheter malfunction or occlusion. In very rare cases, the catheter can be overgrown with fibrin and rigidly connected with the vein or heart structures. This makes its removal almost impossible and dangerous because of the possibility of serious complications, namely vein and heart wall perforation, bleeding, or catheter abruption in deep tissues. We describe two cases in which standard retrieval of long‐term catheters was not possible. Balloon dilatation of catheter lumens was successfully used to increase the catheter diameter with simultaneous tearing of the fibrin sheath surrounding it. This allowed the catheter to be set free safely. Based on this experience, we present recent literature and our point of view. 相似文献
85.
86.
87.
88.
Luszczki JJ Swiader MJ Swiader K Paruszewski R Turski WA Czuczwar SJ 《Neuroscience letters》2007,421(1):87-90
This study focused on the evaluation of anticonvulsant properties of isonicotinic acid benzylamide (iso-Nic-BZA) in numerous experimental seizure models (maximal electroshock [MES]-, bicuculline [BIC]-, pentylenetetrazole [PTZ]-, pilocarpine [PILO]-, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA]-, kainic acid [KA]- and N-methyl-d-aspartic acid [NMDA]-induced seizures). Moreover, acute adverse-effect profile of the agent with respect to impairment of motor coordination was assessed in animals subjected to the chimney test. The evaluation of time-course and dose-response relationships for iso-Nic-BZA provided evidence that the compound produced the peak to maximum antielectroshock action and acute adverse effects at 5min after its systemic (i.p.) administration. Iso-Nic-BZA exerted a clear-cut anticonvulsant action against maximal electroshock-induced seizures in mice and its ED(50) value was 70.6 (56.4-88.4)mg/kg. The assessment of acute adverse effects in the chimney test revealed that the agent produced acute neurotoxic effects and its TD(50) value was 135.6 (108.8-169.0)mg/kg. Additionally, iso-Nic-BZA showed the anticonvulsant activity in numerous chemically-induced seizures (AMPA-, BIC-, KA-, and PTZ-evoked clonic convulsions), remaining virtually ineffective (at doses up to 200mg/kg) in PILO- and NMDA-induced seizures in mice. Based on this study, one can conclude that iso-Nic-BZA due to the short time to peak of its maximum anticonvulsant effects (5min after its i.p. administration), deserves more attention as a potential antiepileptic drug for patients in status epilepticus. 相似文献
89.
The present study tested a hypothesis, whether plant-derived genistein influences the secretion of growth hormone (GH) in ewes, acting directly within the central nervous system (CNS). Starting six weeks after ovariectomy, ewes were infused intracerebroventricularly with genistein (n = 5) or 17beta-estradiol (n = 5), both in a total dose of 40 microg/400 microl/4 h, or with a vehicle (control, n = 5). All infusions were performed from 10:00 AM to 2:00 PM and blood samples were collected from 8:00 AM to 8:00 PM at 10-min intervals. Five genistein- and three vehicle-infused ewes were slaughtered the following morning. The plasma GH concentration was assayed by the radioimmunoassay method, and immunoreactivity of GH in the adenohypophysis was determined by immunohistochemistry. In genistein-infused ewes, mean plasma GH concentration was significantly higher during the whole period of infusion than the concomitant concentration in vehicle-infused ewes. However, examining data within group, GH secretion rose gradually, reaching a significant value during the second phase of genistein infusion. In 17beta-estradiol-infused animals, a significant increase in GH concentration was noted during the first two hours of the infusion, in comparison with vehicle-infused and also in comparison with genistein-infused ewes. Although a gradual increase in basic GH secretion continued in all treated groups during the afternoon and evening, mean plasma GH concentrations in genistein- and 17beta-estradiol-infused ewes were still significantly higher than in the vehicle-infused. The percentage of GH-positive cells in the adenohypophysis and the density of immunoreactive material in these cells decreased significantly in genistein-infused ewes, compared to the control, indicating diminished hormone storage. In conclusion, genistein as 17beta-estradiol, is an effective stimulator of GH secretion in ewes and may exert its effect at the level of the CNS. 相似文献
90.
Effects of JC virus infection on anti-apoptotic protein survivin in progressive multifocal leukoencephalopathy 下载免费PDF全文
Piña-Oviedo S Urbanska K Radhakrishnan S Sweet T Reiss K Khalili K Del Valle L 《The American journal of pathology》2007,170(4):1291-1304
Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease of the central nervous system resulting from the productive infection of oligodendrocytes by the opportunistic polyomavirus JC virus (JCV). Apoptosis is a host defense mechanism to dispose of damaged cells; however, certain viruses have the ability to deregulate apoptotic pathways to complete their life cycles. One such pathway involves survivin, a member of the inhibitor of apoptosis family, which is abundantly expressed during development in proliferating tissues but should be absent in normal, terminally differentiated cells. Immunohistochemistry performed in 20 cases of PML revealed the presence of survivin in JCV-infected oligodendrocytes and bizarre astrocytes within demyelinated plaques. Survivin up-regulation was also found in oligodendroglial and astrocytic cultures infected with JCV. Cell cycle analysis and DNA laddering demonstrated a significantly lower number of cells undergoing apoptosis on JCV infection compared with noninfected cultures; small interfering RNA inhibition of survivin resulted in a dramatic increase in apoptotic cells in JCV-infected cultures. This is the first report describing the activation of survivin by JCV infection in vitro and in PML clinical cases. These observations provide new insights into the anti-apoptotic mechanisms used by JCV to complete its lytic cycle and may suggest new therapeutic targets for PML. 相似文献