全文获取类型
收费全文 | 25077篇 |
免费 | 1752篇 |
国内免费 | 148篇 |
专业分类
耳鼻咽喉 | 201篇 |
儿科学 | 886篇 |
妇产科学 | 710篇 |
基础医学 | 3448篇 |
口腔科学 | 390篇 |
临床医学 | 2620篇 |
内科学 | 5021篇 |
皮肤病学 | 509篇 |
神经病学 | 3092篇 |
特种医学 | 560篇 |
外科学 | 2252篇 |
综合类 | 166篇 |
一般理论 | 38篇 |
预防医学 | 3195篇 |
眼科学 | 304篇 |
药学 | 1525篇 |
1篇 | |
中国医学 | 39篇 |
肿瘤学 | 2020篇 |
出版年
2024年 | 33篇 |
2023年 | 382篇 |
2022年 | 694篇 |
2021年 | 1225篇 |
2020年 | 770篇 |
2019年 | 1013篇 |
2018年 | 1099篇 |
2017年 | 829篇 |
2016年 | 900篇 |
2015年 | 945篇 |
2014年 | 1237篇 |
2013年 | 1505篇 |
2012年 | 2199篇 |
2011年 | 2211篇 |
2010年 | 1166篇 |
2009年 | 964篇 |
2008年 | 1469篇 |
2007年 | 1394篇 |
2006年 | 1323篇 |
2005年 | 1138篇 |
2004年 | 974篇 |
2003年 | 861篇 |
2002年 | 742篇 |
2001年 | 167篇 |
2000年 | 163篇 |
1999年 | 140篇 |
1998年 | 127篇 |
1997年 | 111篇 |
1996年 | 95篇 |
1995年 | 90篇 |
1994年 | 66篇 |
1993年 | 70篇 |
1992年 | 77篇 |
1991年 | 66篇 |
1990年 | 58篇 |
1989年 | 63篇 |
1988年 | 87篇 |
1987年 | 56篇 |
1986年 | 45篇 |
1985年 | 35篇 |
1984年 | 52篇 |
1983年 | 27篇 |
1982年 | 33篇 |
1981年 | 35篇 |
1980年 | 26篇 |
1979年 | 16篇 |
1975年 | 14篇 |
1974年 | 19篇 |
1973年 | 18篇 |
1972年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Aspects of social and emotional competence in adult attention-deficit/hyperactivity disorder 总被引:4,自引:0,他引:4
Friedman SR Rapport LJ Lumley M Tzelepis A VanVoorhis A Stettner L Kakaati L 《Neuropsychology》2003,17(1):50-58
Social and emotional competence were evaluated using self-report and behavioral measures in adults with attention-deficit/hyperactivity disorder (ADHD) and controls. Adults with ADHD viewed themselves as less socially competent but more sensitive toward violations of social norms than controls. Films depicting emotional interactions were used to assess linguistic properties of free recall and perceived emotional intensity. Although adults with ADHD used more words to describe the scenes, they used fewer emotion-related words, despite rating the emotions depicted as more intense than did controls. In contrast, no group differences for words depicting social or cognitive processes were observed. Overall, adults with ADHD appear more aware of their problems in social versus emotional skills. Findings may have implications for improving the psychosocial functioning of these adults. 相似文献
72.
Background
Physicians' awareness of their important role in defusing the obesity epidemic has increased. However, the number of family practitioners who treat obesity problems continues to be low. Self-efficacy refers to the belief in one's ability to organize and execute the courses of action required to produce given attainments. Thus, practitioners who judge themselves incapable of managing obesity do not even try. We hypothesized that practitioners' self-efficacy and motivation would be enhanced as a result of participating in an interactive course designed to enrich their knowledge of obesity management. 相似文献73.
Mast cell tryptase and proteinase-activated receptor 2 induce hyperexcitability of guinea-pig submucosal neurons 总被引:5,自引:2,他引:5
David E. Reed Carlos Barajas-Lopez Graeme Cottrell Sara Velazquez-Rocha Olivier Dery Eileen F. Grady Nigel W. Bunnett Stephen J. Vanner 《The Journal of physiology》2003,547(2):531-542
Mast cells that are in close proximity to autonomic and enteric nerves release several mediators that cause neuronal hyperexcitability. This study examined whether mast cell tryptase evokes acute and long-term hyperexcitability in submucosal neurons from the guinea-pig ileum by activating proteinase-activated receptor 2 (PAR2) on these neurons. We detected the expression of PAR2 in the submucosal plexus using RT-PCR. Most submucosal neurons displayed PAR2 immunoreactivity, including those colocalizing VIP. Brief (minutes) application of selective PAR2 agonists, including trypsin, the activating peptide SL-NH2 and mast cell tryptase, evoked depolarizations of the submucosal neurons, as measured with intracellular recording techniques. The membrane potential returned to resting values following washout of agonists, but most neurons were hyperexcitable for the duration of recordings (> 30 min–hours) and exhibited an increased input resistance and amplitude of fast EPSPs. Trypsin, in the presence of soybean trypsin inhibitor, and the reverse sequence of the activating peptide (LR-NH2 ) had no effect on neuronal membrane potential or long-term excitability. Degranulation of mast cells in the presence of antagonists of established excitatory mast cell mediators (histamine, 5-HT, prostaglandins) also caused depolarization, and following washout of antigen, long-term excitation was observed. Mast cell degranulation resulted in the release of proteases, which desensitized neurons to other agonists of PAR2. Our results suggest that proteases from degranulated mast cells cleave PAR2 on submucosal neurons to cause acute and long-term hyperexcitability. This signalling pathway between immune cells and neurons is a previously unrecognized mechanism that could contribute to chronic alterations in visceral function. 相似文献
74.
Effects of prednisolone treatment on cytokine expression in patients with leprosy type 1 reactions 下载免费PDF全文
Andersson AK Chaduvula M Atkinson SE Khanolkar-Young S Jain S Suneetha L Suneetha S Lockwood DN 《Infection and immunity》2005,73(6):3725-3733
Leprosy type 1 reactions (T1R) are due to increased cell-mediated immunity and result in localized tissue damage. The anti-inflammatory drug prednisolone is used for treatment, but there is little good in vivo data on the molecular actions of prednisolone. We investigated the effect of prednisolone treatment on tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-10, and transforming growth factor beta1 (TGF-beta1) mRNA and protein expression in blood and skin biopsies from 30 patients with T1R in India. After 1 month of prednisolone treatment the sizes of the skin granulomas were reduced, as were the grades of cells positive for TNF-alpha and IL-10 in skin lesions. Increased production of TGF-beta1 was seen in skin lesions after 6 months of prednisolone treatment. Expression of mRNA for TNF-alpha, IL-1beta, and TGF-beta1 was reduced, whereas no change in IL-10 mRNA expression was detected during treatment. The circulating cytokine profiles were similar in patients with and without T1R, and prednisolone treatment had no detectable effects on cytokine expression in the blood. The data emphasize the compartmentalization of pathology in T1R and the importance of the immune response in the skin. Clinical improvement and cytokine expression were compared. Surprisingly, patients with improved skin and nerve function and patients with nonimproved skin and nerve function had similar cytokine profiles, suggesting that clinical improvement is not directly mediated by the cytokines studied here. This in vivo well-controlled study of the immunosuppressive effects of prednisolone showed that the drug does not switch off cytokine responses effectively. 相似文献
75.
Identification of novel virulence-associated genes via genome analysis of hypothetical genes 下载免费PDF全文
The sequencing of bacterial genomes has opened new perspectives for identification of targets for treatment of infectious diseases. We have identified a set of novel virulence-associated genes (vag genes) by comparing the genome sequences of six human pathogens that are known to cause persistent or chronic infections in humans: Yersinia pestis, Neisseria gonorrhoeae, Helicobacter pylori, Borrelia burgdorferi, Streptococcus pneumoniae, and Treponema pallidum. This comparison was limited to genes annotated as hypothetical in the T. pallidum genome project. Seventeen genes with unknown functions were found to be conserved among these pathogens. Insertional inactivation of 14 of these genes generated nine mutants that were attenuated for virulence in a mouse infection model. Out of these nine genes, five were found to be specifically associated with virulence in mice as demonstrated by infection with Yersinia pseudotuberculosis in-frame deletion mutants. In addition, these five vag genes were essential only in vivo, since all the mutants were able to grow in vitro. These genes are broadly conserved among bacteria. Therefore, we propose that the corresponding vag gene products may constitute novel targets for antimicrobial therapy and that some vag mutants could serve as carrier strains for live vaccines. 相似文献
76.
Direct molecular diagnosis of myotonic dystrophy 总被引:2,自引:0,他引:2
B. K. Hecht A. Donnelly A. K. Gedeon R. W. Byard E. A. Haan J. G. Mulley 《Clinical genetics》1993,43(6):276-285
Hecht BK, Donnelly A, Gedeon AK, Byard RW, Haan EA, Mulley JC. Direct molecular diagnosis of myotonic dystrophy. Clin Genet 1993: 43: 276–285. © Munksgaard, 1993 Myotonic dystrophy (DM) arises from an unstable trinucleotide (CTGn) repeat sequence within the DM locus at 19q13.3. Twenty-three myotonic dystrophy families containing 205 persons with no symptoms, minimal manifestations, classic DM or congenital DM were investigated to validate the application of the pM10M6 probe to direct molecular diagnosis. Affected family members had been diagnosed clinically and the unaffected family members had been assigned carrier probabilities close to either zero or 100%, using closely linked flanking markers. Southern analysis identified all 89 DM gene carriers as having expansions of the unstable element. PstI detected all small expansions of the repeat sequence as easily seen discrete bands; but large expansions were usually seen as diffuse smears, sometimes difficult to distinguish from lane background. EcoRI concentrated these diffuse smears, associated with somatic instability, into discrete bands which were easy to detect; but it did not resolve the smaller expansions present in 9 (10%) of the DM carriers. It is essential that PstI and EcoRI gels are run in parallel to detect all DM gene carriers. The extent of expansion of CTG correlated with age of onset and disease severity. Biopsies of various fetal tissues from two terminated pregnancies confirmed the diagnosis obtained by CVS and revealed no heterogeneity between tissues at this developmental stage. Further expansion occurred during the culture of CVS cells, indicating that direct prenatal diagnosis needs to be carried out on CVS tissue rather than on cultured cells. The intergenerational change of the repeat sequence from DM parent to DM offspring showed a significant parental sex difference for those parents with large expansions. Contraction of the unstable element was observed in the three males carrying the largest expansions and could explain why congenital DM is exclusively of maternal origin. 相似文献
77.
Sara Boulaïch Annie Daszuta Michel Geffard Olivier Bosler 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,101(3):353-364
We have previously reported that a cell suspension from the rostral part of the embryonic raphe grafted to the basal hypothalamus of 5,7-dihydroxytryptamine-denervated rats produced incomplete serotonin (5-HT) re-innervation of the suprachiasmatic nucleus (SCN) as opposed to hyper-innervation of the supraoptic nucleus (SON). We took advantage of this experimental model to investigate whether the graft-derived, 5-HT fibres retained normal ultrastructural features, and, particularly, a normal density of synaptic junctions, irrespective of the extent of target re-innervation. The intrinsic features of immunostained, graft-derived 5-HT axonal varicosities in both the SCN (ventral portion) and the SON were essentially similar to those exhibited by the respective endogenous innervation. Analysis of well-preserved varicosities in uninterrupted series of thin sections allowed us to evaluate directly the proportions of junctional to non-junctional 5-HT varicosities in both regions. Synaptic incidences were also remarkably conserved after grafting (45.5% in the SCN versus 38.5% in the SON; 48% and 38% in normal rats, respectively). Synapses were primarily reestablished on dendritic shafts, which also were identified as the major post-synaptic targets of the normal 5-HT innervations. We noted, however, a tendency toward increased numbers of symmetrical versus asymmetrical synapses in both the SCN and SON of grafted rats. Thus, irrespective of whether hypo-or hyper-innervation patterns developed post-grafting, the transplanted 5-HT neurons essentially retained normal ultrastructural features in their target territories, with a normal incidence of synaptic junctions. The data provide further support to the hypothesis that the innervation territory is the major determinant of the frequency with which ingrowing 5-HT fibres make synaptic junctions. 相似文献
78.
79.
80.
Somite stages were employed as units of intrinsic developmental time to measure cell doubling rate and other cell cycle parameters of chick forelimb level somites. Somite cell nuclei doubled over an interval corresponding to approximately 7+ somite stages (7+ ss; approximately 11 hr) and approximately 24 new primary myotome cells are born per somite stage ( approximately 16/hr). FACS analysis of DNA content in dissociated paraxial mesoderm cells indicated that slightly more than half are in G1/G0 phase of the cell cycle and that the average combined length of the S phase and G2 phase intervals is approximately 3 ss ( approximately 4.5 hr). A wavefront of increased mitotic nuclei per segment coincident with somite budding potentially reflects a surge in the number of cells entering S phase 3 ss earlier as each PSM segment becomes unresponsive to FGF signaling as it passes through the determination front. 相似文献