全文获取类型
收费全文 | 228701篇 |
免费 | 17427篇 |
国内免费 | 7821篇 |
专业分类
耳鼻咽喉 | 1257篇 |
儿科学 | 7849篇 |
妇产科学 | 1587篇 |
基础医学 | 19880篇 |
口腔科学 | 3620篇 |
临床医学 | 24396篇 |
内科学 | 58054篇 |
皮肤病学 | 2738篇 |
神经病学 | 26214篇 |
特种医学 | 6780篇 |
外国民族医学 | 4篇 |
外科学 | 18154篇 |
综合类 | 31061篇 |
现状与发展 | 31篇 |
一般理论 | 9篇 |
预防医学 | 19069篇 |
眼科学 | 2390篇 |
药学 | 15895篇 |
198篇 | |
中国医学 | 10326篇 |
肿瘤学 | 4437篇 |
出版年
2024年 | 666篇 |
2023年 | 4817篇 |
2022年 | 8668篇 |
2021年 | 12243篇 |
2020年 | 11433篇 |
2019年 | 8616篇 |
2018年 | 8560篇 |
2017年 | 8445篇 |
2016年 | 8831篇 |
2015年 | 8513篇 |
2014年 | 16268篇 |
2013年 | 17666篇 |
2012年 | 13288篇 |
2011年 | 14367篇 |
2010年 | 11327篇 |
2009年 | 10822篇 |
2008年 | 10896篇 |
2007年 | 10568篇 |
2006年 | 9360篇 |
2005年 | 7700篇 |
2004年 | 6506篇 |
2003年 | 5600篇 |
2002年 | 4700篇 |
2001年 | 4086篇 |
2000年 | 3401篇 |
1999年 | 2909篇 |
1998年 | 2763篇 |
1997年 | 2452篇 |
1996年 | 2182篇 |
1995年 | 1972篇 |
1994年 | 1819篇 |
1993年 | 1549篇 |
1992年 | 1494篇 |
1991年 | 1306篇 |
1990年 | 1058篇 |
1989年 | 891篇 |
1988年 | 825篇 |
1987年 | 748篇 |
1986年 | 659篇 |
1985年 | 759篇 |
1984年 | 638篇 |
1983年 | 388篇 |
1982年 | 476篇 |
1981年 | 394篇 |
1980年 | 297篇 |
1979年 | 264篇 |
1978年 | 202篇 |
1977年 | 180篇 |
1976年 | 141篇 |
1975年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Select types of supporting cell in the inner ear express aquaporin-4 water channel protein 总被引:14,自引:0,他引:14
Yutaka Takumi Erlend Arnulf Nagelhus Jo Eidet Atsushi Matsubara Shin-ichi Usami Hideichi Shinkawa Søren Nielsen Ole Petter Ottersen 《The European journal of neuroscience》1998,10(12):3584-3595
Aquaporins (AQPs) confer a high water permeability on cell membranes and play important parts in secretory and absorptive epithelia in kidney and other organs. Here we investigate whether AQPs are expressed in the sensory epithelia of the inner ear, where a precise volume regulation is crucial. By use of specific antibodies it was found that the inner ear contains AQP1 and 4 while being devoid of detectable levels of AQP2, 3 or 5. Immunofluorescence and postembedding immunogold labelling revealed a strictly non-epithelial distribution of AQP1, confirming previous data. In contrast, AQP4 protein and mRNA (visualized by in situ hybridization) were concentrated in select types of supporting cell, including Hensen's cells and inner sulcus cells. Immunogold particles signalling AQP4 were confined to the basolateral plasma membrane of Hensen's cells and to the basal plasma membrane of Claudius cells and inner sulcus cells. AQP4 was also found in supporting cells of the vestibular end organs, but was absent from transitional epithelial cells and dark cells. Strong labelling for AQP4 and AQP4-mRNA was associated with the central part of the cochlear and vestibular nerves. Hair cells were consistently unlabelled. Our findings indicate that AQP4 may facilitate osmotically driven water fluxes in the sensory epithelia of the inner ear and thus contribute to the volume and ion homeostasis at these sites. 相似文献
992.
Ayala Stabholz Anne A. Nicholas Grenith J. Zimmerman Ulf M. E. Wikesjö 《Journal of clinical periodontology》1998,25(10):794-800
Abstract. 15 adults, each providing 4 non-adjacent untreated periodontal pockets with a probing depth (PD) exceeding 6 mm. volunteered for a randomized, split-mouth, double-blind, clinical study evaluating subgingival irrigation with chlorhexidine (CHX) or tetracycline HCl (TTC). The study protocol included oral hygiene instructions followed by scaling and root planing. Experimental and immediately adjacent teeth did not receive instrumentation. The 4 deep periodontal pockets in each patient were assigned to be irrigated with 150 ml CHX (0.12%). TTC (10 or 50 mg/ml; TTC10, TTC50), or sterile saline (control) in a single episode. Post-irrigation mechanical plaque control was supported by 2× daily CHX rinses throughout the 12-week observation interval. Recordings of oral hygiene (PlI), gingival health (GI). bleeding on probing (BoP). probing depth (PD), clinical attachment level (CAL), and microbial morphotypes from subgingival paper point samples were performed pre-irrigation. and at 1, 2, 4, 6, 8, 10, and 12 weeks post-irrigation. Mean post-irrigation PlI was low, fluctuating between 0.0 and 0.4, without significant differences between experimental groups. Mean pre-irrigation GI approximated 1.4 and reached 0.8 at the exit of study without significant differences between experimental groups. All experimental sites exhibited BoP pre-irrigation. BoP was significantly reduced in TTC50 compared to TTC10, CHX and control sites from week 8 post-irrigation. PDs were reduced for the experimental groups with TTC50 exhibiting the strongest reduction. CALs remained unaltered from pre-irrigation for TTC10. CHX and control sites over the 12-week observation interval, whereas TTC50 sites consistently improved to significantly differ from all other groups at week 10 and 12 post-irrigation. The distribution of bacterial morphotypes was significantly altered towards one of periodontal health for all experimental groups with a profound effect for TTC50 sites. Our results suggest that subgingival irrigation with TTC solutions at high concentrations may have a rôle in the management of adult periodontitis. 相似文献
993.
In two patients with Crohn's disease, strictureplasties had been marked operatively by a metal clip, so that definitive location on subsequent small bowel examination was possible. Each stricture-plasty presented radiologically as a short annular constriction with apparently shouldered edges and parallel lumen. Similar radiological features were found in five other patients with strictureplasties, suggesting that a pseudotumoral appearance is characteristic of strictureplasty. Attention is drawn to this finding to avoid confusion with malignancy. 相似文献
994.
Wagner Jurgen; Madry Henning; Reszka Regina 《Nephrology, dialysis, transplantation》1995,10(10):1801-1807
Renal gene transfer techniques are being developed as a novelexperimental approach to understand the pathogenesis of renaldisease and to potentially develop new therapeutic tools. Wereview the currently available technology to introduce foreigngenetic material into renal tissue, i.e., retroviral, adenoviral,and liposomal transfer systems with their respective advantagesand caveats. Today, the transfer efficiency of these methodsappears to be sufficiently high to study the effects of transducedgenes on renal function and morphology in rat kidney. This willallow (i) the elucidation of the function of genes on the courseof renal disease in experimental animal models and (ii) themodulation of local expression of endogenous genes which presumptivelycontribute to renal pathology in these models. One strategyto accomplish this aim is the use of recombinant DNA technologyto design antisense DNA constructs or oligonucleotides, whichinterfere with the renal expression of target genes. We willalso discuss some of the shortcomings of the currently usedtechniques with respect to potential therapeutic use of genetransfer systems and gene modulation. 相似文献
995.
急性心肌梗塞患者血清唾液酸含量测定 总被引:2,自引:0,他引:2
本文测定了50例正常人,32例急性心肌梗塞,54例冠心病无梗塞者血清SA水平,结果表明,急性心肌梗塞组血清SA水平与冠心病无梗塞组及正常人相比,具显著性差异,可能与心肌梗塞造成心肌细胞受损所致使细胞表面成份释放入血有关,所以血清SA测定可提供一新的心肌梗塞诊断依据。 相似文献
996.
Complete congenital heart block (CCHB) affects 1:20,000–25,000 live births and is usually an atrioventricular block; 30–50% of fetuses with CCHB will have a structural anomaly, though recently attention has focused on the etiological influence of autoimmune disease, such as systemic lupus erythematosus. The diagnosis is established by detailed two-dimensional ultrasound scanning of the heart to exclude anomaly coupled with M-mode echocardiography and Doppler blood velocity patterns in the major vessels to detect the uncoupling of atrial and ventricular rhythms. Risk factors for an affected child are discussed. A previously affected child, high titers of anti-Ro antibodies, the presence of anti-Ro (SS-A) and anti-La (SS-B), and maternal HLA DR3 confer high risk. Antibody mediated CCHB is irreversible. Plasmapheresis and immunosuppression have been attempted in affected mothers, with limited success, to reduce the likelihood of the fetus being affected, and steroids have been used to reduce the inflammatory reaction in the heart. In many cases the underlying pathology of the immune system adversely affects utero-placental function requiring careful monitoring of fetal well-being. CCHB renders fetal heart rate monitoring virtually useless, in the antenatal and intrapartum periods. Alternatives are explored. 相似文献
997.
Langerhans cell histiocytosis includes three clinical forms of histocytosis X. We describe a disseminated form of Langerhans cell histiocytosis (Letterer-Siwe disease) in monozygotic twins. The twins showed simultaneous onset of disease, almost identical clinical follow-up and findings on cranial CT. The cause of this phenomenon remains unknown. 相似文献
998.
Steffen Roiner Nikolas Bakinde Ulrike Zeitschel Reinhard Schliebs Volker Bigl 《International journal of developmental neuroscience》1998,16(7-8):669-673
The present study was conducted to test the hypothesis that cholinergic basalforebrain neurons are a major source of cerebrospinal fluid (CSF) cholinesterases. To address thisquestion enzyme activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inboth CSF and parietal cortex were assayed following selective lesion of basal forebrain cholinergicneurons by a single intracerebroventricular application of the cholinergic immunotoxin192IgG-saporin. Cholinergic immunolesions led to a dramatic decrease in total AChE activity inparietal cortex, which was due to the specific loss of the G4 molecular form while the activity ofthe G1 form was increased as compared to nonlesioned animals. In contrast, the total enzymeactivity of BChE and its molecular forms were not affected by cholinergic lesion in both parietalcortex and CSF. The data suggest, that cholinergic basal forebrain neurons are seemingly not amajor source of cholinesterases in the CSF, and do not provide any evidence for using CSFcholinesterases as a diagnostic marker of basal forebrain cholinergic cell loss in humans. 相似文献
999.
冠心病中血糖与血清微量元素间的关系分析 总被引:1,自引:0,他引:1
对75例冠心病患者依血糖水平分两组,进行12种血清微量元素测定,旨在探讨微量元素与冠心病及糖尿病间的相互关系。结果发现锌、铬、锰、硒、钴元素高血糖组较对照组血清水平为低,呈非常显著差异(P<0.0l);铜、镍元素增高,差异显著(P<0.05);而锶、铁、砷、铅、铝元素两组间无显著差异(P>0.1)。表明部分微量元素与冠心病及血糖间存在着密切联系。 相似文献
1000.
A cerebral type of Lewy body disease (LBD) is proposed. Lewy body disease was split formerly into three types: brainstem type, transitional type and diffuse type. The diffuse type is now called diffuse Lewy body disease (DLBD). These three types are characterized pathologically by the presence of a large number of Lewy bodies in the CNS. In the brainstem type, Lewy bodies are numerous in the brainstem and diencephalon nuclei, and in DLBD, a vast number are present not only in these nuclei but also in the cerebral cortex and amygdala. In the cerebral type of LBD, as many Lewy bodies are found in the cerebral cortex and in the amygdala as there are in DLBD, but only rarely are they present in the brainstem and diencephalon nuclei. Thus, this type of LBD is different from other types in that it has no parkinson pathology. Therefore, parkinsonism fails to occur throughout the whole clinical course of this disease. The existence of a cerebral type of LBD suggests that Lewy bodies occur in the cerebral cortex earlier than in the brainstem nuclei and that cortical Lewy bodies appear even when the mesocortical dopaminergic system is intact. In addition, this might explain why dementia frequently precedes parkinsonism in DLBD. 相似文献