全文获取类型
收费全文 | 2533篇 |
免费 | 133篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 40篇 |
妇产科学 | 39篇 |
基础医学 | 371篇 |
口腔科学 | 26篇 |
临床医学 | 291篇 |
内科学 | 610篇 |
皮肤病学 | 56篇 |
神经病学 | 298篇 |
特种医学 | 29篇 |
外科学 | 179篇 |
综合类 | 5篇 |
一般理论 | 1篇 |
预防医学 | 268篇 |
眼科学 | 45篇 |
药学 | 208篇 |
中国医学 | 9篇 |
肿瘤学 | 184篇 |
出版年
2024年 | 16篇 |
2023年 | 31篇 |
2022年 | 109篇 |
2021年 | 114篇 |
2020年 | 82篇 |
2019年 | 94篇 |
2018年 | 81篇 |
2017年 | 76篇 |
2016年 | 66篇 |
2015年 | 77篇 |
2014年 | 124篇 |
2013年 | 124篇 |
2012年 | 184篇 |
2011年 | 203篇 |
2010年 | 83篇 |
2009年 | 104篇 |
2008年 | 124篇 |
2007年 | 145篇 |
2006年 | 123篇 |
2005年 | 126篇 |
2004年 | 112篇 |
2003年 | 128篇 |
2002年 | 118篇 |
2001年 | 20篇 |
2000年 | 27篇 |
1999年 | 23篇 |
1998年 | 23篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 16篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1974年 | 5篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1966年 | 3篇 |
1949年 | 1篇 |
排序方式: 共有2679条查询结果,搜索用时 15 毫秒
21.
Iori AP Torelli GF De Propris MS Milano F Pupella S Gozzer M Mancini F Milani ML Intoppa S Cerretti R Lucarelli B Valle V Malandruccolo L Iannella E Arleo E Guarini A Foà R 《Transplantation》2008,85(3):386-390
BACKGROUND: The influence of the graft composition on the clinical outcome after allogeneic peripheral blood stem cell (PBSC) transplantation is not well established. METHODS: The cellular composition of the apheretic products obtained from 63 human leukocyte antigen-identical siblings was prospectively correlated with the outcome of patients with hematological malignancies undergoing an allogeneic PBSC transplant after myeloablative conditioning. The concentration of nuclear, mononuclear, CD34+, T-cell subsets, B cells, and natural killer cells in the graft has been analyzed. RESULTS: In univariate analysis, acute graft-versus-host disease (GVHD) correlated with the disease (P=0.002), with the phase of disease at transplant (P=0.01), and with the number of CD20+ cells infused (P=0.05). In multivariate analysis, a dose of CD20+ cells in the graft higher than the median dose remained the only factor negatively affecting the incidence of acute GVHD (P=0.01; 95% confidence interval [CI]: 0.12-0.78). In univariate analysis, treatment-related mortality (TRM) correlated with the disease (P=0.04) and was negatively affected by a dose of infused B cells greater than the median value (28% versus 50%; P=0.02). In multivariate analysis, TRM was close to statistical correlation with the dose of CD20+ cells (P=0.06; 95% CI: 0.02-1.05). No other clinical parameter was influenced by the composition of the graft. CONCLUSIONS: Our results suggest that the concentration of B cells in the apheretic product may predict the incidence of acute GVHD and TRM in patients undergoing an allogeneic PBSC transplantation and open the way to the new preventive and therapeutic strategies for the management of GVHD. 相似文献
22.
Salvage cryotherapy using an argon based system for locally recurrent prostate cancer after radiation therapy: the Columbia experience 总被引:7,自引:0,他引:7
Ghafar MA Johnson CW De La Taille A Benson MC Bagiella E Fatal M Olsson CA Katz AE 《The Journal of urology》2001,166(4):1333-7; discussion 1337-8
PURPOSE: Cryosurgical ablation of the prostate has been reported as potential treatment for radioresistant clinically localized prostate cancer. We report our experience with the safety and efficacy of salvage cryosurgery using the argon based CRYOCare system (Endocare, Inc, Irvine, California). MATERIALS AND METHODS: Between October 1997 and September 2000, 38 men with a mean age of 71.9 years underwent salvage cryosurgery for recurrent prostate cancer after radiation therapy failed. All patients had biochemical disease recurrence, defined as an increase in prostate specific antigen (PSA) of greater than 0.3 ng./ml. above the post-radiation PSA nadir. Subsequently prostate biopsy was positive for cancer. Pre-cryosurgery bone scan demonstrated no evidence of metastatic disease. In addition, these patients received 3 months of neoadjuvant androgen deprivation therapy before cryotherapy. RESULTS: The PSA nadir was 0.1 or less, 1 or less and greater than 1 ng./ml. in 31 (81.5%), 5 (13.2%) and 2 (5.3%) patients, respectively. Biochemical recurrence-free survival calculated from Kaplan-Meier curves was 86% at 1 year and 74% at 2 years. Reported complications included rectal pain in 39.5% of cases, urinary tract infection in 2.6%, incontinence in 7.9%, hematuria in 7.9% and scrotal edema in 10.5%. The rate of rectourethral fistula, urethral sloughing and urinary retention was 0%. CONCLUSIONS: Our study supports cryosurgery of the prostate as safe and effective treatment in patients in whom radiation therapy fails. Using the CRYOCare machine resulted in a marked decrease in complications. 相似文献
23.
24.
Marco Monticone Emilia Ambrosini Barbara Rocca Silvia Magni Flavia Brivio Simona Ferrante 《European spine journal》2014,23(10):2105-2113
Purpose
To evaluate the effect of a multidisciplinary rehabilitation programme on disability, kinesiophobia, catastrophizing, pain, quality of life and gait disturbances in patients with chronic low back pain (CLBP).Methods
This was a parallel-group, randomised, superiority-controlled pilot study in which 20 patients were randomly assigned to a programme consisting of motor training (spinal stabilising exercises plus usual-care) and cognitive–behavioural therapy (experimental group, 10 subjects) or usual-care alone (control group, 10 subjects). Before treatment, 8 weeks later (post-treatment), and 3 months after the end of treatment, the Oswestry Disability Index, the Tampa Scale for Kinesiophobia, the Pain Catastrophizing Scale, a pain numerical rating scale, and the Short-Form Health Survey were assessed. Spatio-temporal gait parameters were also measured by means of an electronic walking mat. A linear mixed model for repeated measures was used for each outcome measure.Results
The programme had significant group (p = 0.027), time (p < 0.001), and time-by-group interaction (p < 0.001) effects on disability, with the experimental group showing an improvement after training of about 61 % (25 % in the control group). The analyses of kinesiophobia, catastrophizing, and the quality of life also revealed significant time, group, and time-by-group interaction effects in favour of the experimental group, and there was a significant effect of time on pain. Both groups showed a general improvement in gait parameters, with the experimental group increasing cadence significantly more.Conclusion
The multidisciplinary rehabilitation programme including cognitive–behavioural therapy was superior to the exercise programme in reducing disability, kinesiophobia, catastrophizing, and enhancing the quality of life and gait cadence of patients with CLBP. 相似文献25.
Sessa A Battini G Meroni M Pitingolo F Righetti M Ciotti P Di Maria E Bellone E Ajmar F Mandich P 《Journal of nephrology》2005,18(2):209-212
Von Hippel-Lindau (VHL) disease is a rare autosomal dominant disorder characterized by multifocal and bilateral renal cell carcinoma and cysts, retinal angiomas, hemangioblastoma of the central nervous system, pheochromocytoma, epididymis cystoadenoma, pancreatic cysts and/or islet cell tumors. However, phenotypic manifestations and clinical outcome are wide ranging including inter and intra-familial patterns. The VHL gene has been localized on chromosome 3 p 25-26 and more than 250 germline mutations have been described. The sensitivity of analytic techniques of VHL gene is close to 100%. It is well known that about 25% of VHL patients present de novo mutations, and first cases function as possible founders of new VHL kindreds. Herein, we report the clinical case of a 45-year-old Caucasian female patient affected by bilateral polycystic kidney disease with two renal carcinomas in both kidneys without lynphoadenopathies. She underwent ophthalmologic surgery at 19 years old because of retinal detachment due to bilateral retinal angiomatosis. Direct gene sequencing showed a deletion-insertion in exon 3, starting from nucleotide 499 of the coding sequence (c.499-504 delinstT) in a heterozygous status; it causes a frame-shift and creates a premature stop at codon 170. The genetic study of the unaffected parents and of the unaffected brother confirmed the diagnosis of de novo VHL disease with the dentification of a new germline mutation, never reported in the literature. The patient showed normal kidney function and she did not show other organ lesions or clinical manifestations of VHL disease. She was successfully submitted to renal parenchymal sparing-surgery. In conclusion, it is important to test for germline mutations in VHL patients with the involvement of one organ or a pair of organs. Once the mutation is found in the proband, all family members can be easily tested for the documented mutation. The early identification of VHL patients is very important for clinical and genetic reasons. 相似文献
26.
Pierrotti LC Etzel A Sumita LM Braga PE Eluf-Neto J de Souza VA Segurado AA 《Sexually transmitted diseases》2005,32(1):57-63
GOAL: The goal of this study was to evaluate the seroprevalence of human herpesvirus 8 (HHV-8) infection among HIV-infected individuals from Brazil and the associated risk factors. STUDY: A cross-sectional survey was carried out with 497 HIV/AIDS outpatients attending the local AIDS Reference Center in Santos (southeastern Brazil) between February 1997 and January 1998 had serum samples screened for anti-HHV-8 antibodies. Patients were considered seropositive whenever reactivity was observed in at least 1 of 3 tests (immunofluorescence assays for latent nuclear and lytic antigens and orf65 recombinant antigen enzyme-linked immunosorbent assay). RESULTS: Overall HHV-8 seroprevalence was 13.9% (95% confidence interval [CI], 10.9-17.6). HHV-8 coinfection was significantly more frequent in men (18.7%; 95% CI, 14.1-23.4) than in women (7.8%; 95% CI, 4.2-11.3) (P < 0.001). According to the mode of HIV acquisition among males, seroprevalence of HHV-8 infection was significantly higher in men who have sex with men when compared with the other groups (32.4% vs. 10.0%, P < 0.001). Multivariate logistic regression revealed HHV-8 infection among men to be independently associated with sexual orientation (adjusted odds ratio [AOR], 5.5 for homosexuals; AOR, 2.8 for bisexuals). No significant risk factor for HHV-8 infection could be demonstrated for HIV-infected women in this cohort, CONCLUSIONS: This study provides further evidence that men who have sex with men are at higher risk of HHV-8 infection and shows that the epidemiologic pattern of this infection among HIV/AIDS patients from Santos, Brazil, is similar to that described in other countries with a low incidence of Kaposi's sarcoma. 相似文献
27.
28.
29.
Galdiero Emilia Siciliano Antonietta Lombardi Lucia Falanga Annarita Galdiero Stefania Martucci Francesca Guida Marco 《Ecotoxicology (London, England)》2020,29(2):156-162
Ecotoxicology - Nanomaterials have revolutionized many scientific fields and are widely applied to address environmental problems and to develop novel health care strategies. However, their... 相似文献
30.
Emilia C. Arturo Kushol Gupta Annie Héroux Linda Stith Penelope J. Cross Emily J. Parker Patrick J. Loll Eileen K. Jaffe 《Proceedings of the National Academy of Sciences of the United States of America》2016,113(9):2394-2399
Improved understanding of the relationship among structure, dynamics, and function for the enzyme phenylalanine hydroxylase (PAH) can lead to needed new therapies for phenylketonuria, the most common inborn error of amino acid metabolism. PAH is a multidomain homo-multimeric protein whose conformation and multimerization properties respond to allosteric activation by the substrate phenylalanine (Phe); the allosteric regulation is necessary to maintain Phe below neurotoxic levels. A recently introduced model for allosteric regulation of PAH involves major domain motions and architecturally distinct PAH tetramers [Jaffe EK, Stith L, Lawrence SH, Andrake M, Dunbrack RL, Jr (2013) Arch Biochem Biophys 530(2):73–82]. Herein, we present, to our knowledge, the first X-ray crystal structure for a full-length mammalian (rat) PAH in an autoinhibited conformation. Chromatographic isolation of a monodisperse tetrameric PAH, in the absence of Phe, facilitated determination of the 2.9 Å crystal structure. The structure of full-length PAH supersedes a composite homology model that had been used extensively to rationalize phenylketonuria genotype–phenotype relationships. Small-angle X-ray scattering (SAXS) confirms that this tetramer, which dominates in the absence of Phe, is different from a Phe-stabilized allosterically activated PAH tetramer. The lack of structural detail for activated PAH remains a barrier to complete understanding of phenylketonuria genotype–phenotype relationships. Nevertheless, the use of SAXS and X-ray crystallography together to inspect PAH structure provides, to our knowledge, the first complete view of the enzyme in a tetrameric form that was not possible with prior partial crystal structures, and facilitates interpretation of a wealth of biochemical and structural data that was hitherto impossible to evaluate.Mammalian phenylalanine hydroxylase (PAH) (EC 1.14.16.1) is a multidomain homo-multimeric protein whose dysfunction causes the most common inborn error in amino acid metabolism, phenylketonuria (PKU), and milder forms of hyperphenylalaninemia (OMIM 261600) (1). PAH catalyzes the hydroxylation of phenylalanine (Phe) to tyrosine, using nonheme iron and the cosubstrates tetrahydrobiopterin and molecular oxygen (2, 3). A detailed kinetic mechanism has recently been derived from elegant single-turnover studies (4). PAH activity must be carefully regulated, because although Phe is an essential amino acid, high Phe levels are neurotoxic. Thus, Phe allosterically activates PAH by binding to a regulatory domain. Phosphorylation at Ser16 potentiates the effects of Phe, with phosphorylated PAH achieving full activation at lower Phe concentrations than the unphosphorylated protein (5, 6). Allosteric activation by Phe is accompanied by a major conformational change, as evidenced by changes in protein fluorescence and proteolytic susceptibility, and by stabilization of a tetrameric conformer (3).There are >500 disease-associated missense variants of human PAH; the amino acid substitutions are distributed throughout the 452-residue protein and among all its domains (Fig. 1A) (7–9). Of those disease-associated variants that have been studied in vitro (e.g., ref. 10), some confound the allosteric response, and some are interpreted as structurally unstable. We also suggest that the activities of some disease-associated variants may be dysregulated by an altered equilibrium among conformers having different intrinsic levels of activity, arguing by analogy to the enzyme porphobilinogen synthase (PBGS) and its porphyria-associated variants (11). Consistent with this notion, we have recently established that PAH can assemble into architecturally distinct tetrameric conformers (12), and propose that these conformers differ in activity due to differences in active-site access. This idea has important implications for drug discovery, as it implies that small molecules could potentially modulate the conformational equilibrium of PAH, as has already been demonstrated for PBGS (e.g., ref. 13). Deciphering the relationship among PAH structure, dynamics, and function is a necessary first step in testing this hypothesis.Open in a separate windowFig. 1.The structure of PAH. (A) The annotated domain structure of mammalian PAH. (B) The 2.9 Å PAH crystal structure in orthogonal views, colored as in part A, subunit A is shown in ribbons; subunit B is as a Cα trace; subunit C is in sticks; and subunit D is in transparent spheres. In cyan, the subunits are labeled near the catalytic domain (Top); in red, they are labeled near the regulatory domain (Bottom). The dotted black circle illustrates the autoregulatory domain partially occluding the enzyme active site (iron, in orange sphere). (C) Comparison of the subunit structures of full-length PAH and those of the composite homology model; the subunit overlay aligns residues 144–410. The four subunits of the full-length PAH structure (the diagonal pairs of subunits are illustrated using either black or white) are aligned with the two subunits of 2PAH (cyan) and the one subunit of 1PHZ (orange). The catalytic domain is in spheres, the regulatory domain is in ribbons, and the multimerization domain is as a Cα trace. The arrow denotes where the ACT domain and one helix of 2PAH conflict.Numerous crystal structures are known for one- and two-domain constructs of mammalian PAH (14).
Open in a separate windowEntries are colored by configuration of the active-site lid (approximately residues 130–150): “open,” “closed,” and “disordered.”*C, catalytic domain, M, multimerization domain; R, regulatory domain.†wwPDB Chemical Component Dictionary (49).‡Disease-associated single-residue substituted variant (A313T).§Phosphorylated at Ser16. 相似文献