全文获取类型
收费全文 | 6138篇 |
免费 | 382篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 31篇 |
儿科学 | 198篇 |
妇产科学 | 132篇 |
基础医学 | 866篇 |
口腔科学 | 267篇 |
临床医学 | 461篇 |
内科学 | 1666篇 |
皮肤病学 | 148篇 |
神经病学 | 618篇 |
特种医学 | 144篇 |
外科学 | 512篇 |
综合类 | 9篇 |
一般理论 | 2篇 |
预防医学 | 323篇 |
眼科学 | 28篇 |
药学 | 412篇 |
中国医学 | 5篇 |
肿瘤学 | 754篇 |
出版年
2024年 | 9篇 |
2023年 | 77篇 |
2022年 | 117篇 |
2021年 | 200篇 |
2020年 | 125篇 |
2019年 | 150篇 |
2018年 | 182篇 |
2017年 | 114篇 |
2016年 | 151篇 |
2015年 | 183篇 |
2014年 | 256篇 |
2013年 | 327篇 |
2012年 | 506篇 |
2011年 | 468篇 |
2010年 | 278篇 |
2009年 | 239篇 |
2008年 | 437篇 |
2007年 | 412篇 |
2006年 | 395篇 |
2005年 | 391篇 |
2004年 | 338篇 |
2003年 | 313篇 |
2002年 | 324篇 |
2001年 | 45篇 |
2000年 | 31篇 |
1999年 | 34篇 |
1998年 | 53篇 |
1997年 | 48篇 |
1996年 | 38篇 |
1995年 | 39篇 |
1994年 | 35篇 |
1993年 | 16篇 |
1992年 | 27篇 |
1991年 | 23篇 |
1990年 | 21篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 6篇 |
1986年 | 20篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有6576条查询结果,搜索用时 593 毫秒
81.
Cerebellar binding of avian pancreatic polypeptide 总被引:2,自引:0,他引:2
Studies were carried out to determine the regional central nervous system and species specificity of the previously observed [125I]iodoavian pancreatic polypeptide ( [125I]iodo-APP) specific binding to chick brain membranes. The avian species examined were chicken, pigeon, duck, quail, chukar, and pheasant. In all species, the vast majority (greater than 90%) of APP binding was localized to the area of the cerebellum; other brain regions specifically bound small amounts of APP. Cerebellar hemisphere (folia) regions may have greater specific binding capacities than deep cerebellar nuclei, although all avian cerebellar preparations exhibited affinities for APP on the order of 10(-10) M and binding capacities from approximately 0.2-1.5 pmol/mg protein for the high affinity sites. The measured affinity for binding of APP to these cerebellar binding sites is consistent with normal plasma concentrations (3-6 ng/ml) of APP in all Aves examined. Mammalian (rat and beef) brain membranes, regardless of topographical region, showed low specific binding of [125I]iodo-APP and [125I]iodobovine PP. Preliminary experiments indicate that APP is neither contained in nor released from avian central nervous system synaptosomal elements. 相似文献
82.
Vinci G Anjot MN Trivin C Lottmann H Brauner R McElreavey K 《The Journal of clinical endocrinology and metabolism》2004,89(12):6282-6285
Anorchia, or the "vanishing testis syndrome," is characterized by the absence of testis in a 46,XY individual with a male phenotype. The etiology is unknown; however, the familial occurrence of the disease and the association of this phenotype with 46,XY gonadal dysgenesis has led to the suggestion that genetic factors, which play a role in testicular determination, may be involved. Alternatively, exploratory laparoscopy has suggested that anorchia may be caused by a prenatal testicular vascular accident associated with torsion during testicular descent. We screened a cohort of 14 boys with bilateral anorchia for mutations in the Y chromosome-linked testis-determining gene SRY (sex-determining region, Y chromosome); in the gene necessary for correct testicular descent, INSL3; and in the gene of its receptor (LGR8). Mutations in the INSL3 gene and the LGR8 T222P mutation are known to cause cryptorchidism. We confirmed previous reports that mutations in the SRY gene are not associated with anorchia. Although a common polymorphism was identified in the INSL3 gene, no mutations were observed. The recurrent T222P mutation in the LGR8 gene was not found in any of the patients. These data show for the first time a lack of association between genetic factors necessary for correct testicular descent and anorchia. 相似文献
83.
Imbrogno S Angelone T Corti A Adamo C Helle KB Tota B 《General and comparative endocrinology》2004,139(1):20-28
We have studied the effects of exogenous human recombinant Vasostatin-1 (VS-1), Vasostatin-2 (VS-2) and the human Chromogranin A (CGA) 7-57 synthetic peptides on the mechanical performance of the isolated and perfused working eel (Anguilla anguilla) heart. Under basal conditions, the three peptides decreased stroke volume (SV) and stroke work (SW), thus exerting negative inotropism. The VS-1-mediated negative inotropism was abolished by exposure to inhibitors of either Gi/o protein (pertussis toxin; PTx) or M1 muscarinic receptors (Pirenzepine) or calcium (Lantanum and Diltiazem) and potassium (Ba2+, 4-aminopyridine, tetraethylammonium, glibenclamide) channels, while it required an intact endocardial endothelium (EE). Using NG-monomethyl-L-arginine (L-NMMA) as an inhibitor of nitric oxide (NO) synthase (NOS), and hemoglobin as a NO scavenger, we demonstrated the obligatory role of NO signaling in mediating the vasostatin response. Pretreatment with either a specific inhibitor of soluble guanylate cyclase (GC) 1H-(1,2,4)oxadiazolo-(4,3-a)quinoxalin-1-one (ODQ), or the inhibitor of the cGMP-activated protein kinase (PKG) KT5823, abolished the VS-1-mediated inotropism, indicating the cGMP-PKG component as a crucial target of NO signaling. Of note, VS-1 was effective in counteracting the adrenergic (Isoproterenol and Phenylephrine)-mediated positive inotropism. These findings provide the first evidence that vasostatins exert cardiotropic action in fish, thus suggesting their long evolutionary history as well as their species-specific mechanisms of action. 相似文献
84.
Giebel S Locatelli F Wojnar J Velardi A Mina T Giorgiani G Krawczyk-Kulis M Markiewicz M Wylezol I Holowiecki J 《British journal of haematology》2005,131(4):483-486
Human leucocyte antigen (HLA)-C molecules regulate the function of natural killer cells and may be subdivided into two groups, C(1) and C(2), based on their specificity for inhibitory killer immunoglobulin-like receptors. We analysed the impact of the HLA-C genotype on outcome of HLA-C-matched unrelated donor haematopoietic stem cell transplantation (URD-HSCT) recipients. HLA-C(2) homozygous patients (n = 18) had lower probability of overall survival (P = 0.01) and disease-free survival (P = 0.02), resulting from increased relapse rate (P = 0.02) when compared with both HLA-C(1) homozygous (n = 43) and HLA-C(1),C(2) heterozygous (n = 50) subgroups. Patients lacking HLA-C(1) should, therefore, be considered at increased risk of relapse following HLA-C-matched URD-HSCT. 相似文献
85.
Luna Gargani Cosimo Bruni Tatiana Barskova Valentina Hartwig Martina Marinelli Maria Giovanna Trivella Marco Matucci-Cerinic Antonio LAbbate 《Seminars in arthritis and rheumatism》2019,48(5):867-873
Objectives
Systemic sclerosis (SSc) causes functional and structural microcirculatory dysfunction, affecting also distal extremities. Optical Near-InfraRed Spectroscopy (NIRS) of blood HbO2 saturation (stO2) is able to evaluate O2 delivery/consumption balance in the explored tissue. The NIRS-sensitive camera non-invasively detects stO2 values in superficial tissues, automatically generating 2D-imaging maps in real time. We aimed at testing whether NIRS hand imaging may evaluate peripheral microcirculatory dysfunction and its spatial heterogeneity in SSc patients compared to controls.Methods
Forty SSc patients (aged 55.1?±?15.6 years) and twenty-one healthy controls (aged 54.3?±?14.5years, p?=?0.89) were studied by palmar hand NIRS-2D imaging. A blood pressure cuff was applied to the forearm and 3 min ischemia was induced. Images were acquired at basal conditions and every 10 seconds during 3 minutes of ischemia and 5 minutes of reperfusion. Five regions of interest were positioned on each fingertip, from the second to the fifth finger and one on the thenar eminence.Results
A significant difference was found between controls and SSc patients in basal stO2 (84.3?±?7.5?vs. 75.4?±?10.9%, p?<?0.001), minimum stO2 (65.2?±?8.0?vs. 53.4?±?10.1%, p?<?0.001) and time to maximum stO2 during hyperemia (63?±?38?vs. 85?±?49?s, p?<?0.05). Among clinical characteristics, anti-Scl70 antibody positivity, digital ulcers history and smoke exposure affected NIRS parameters, as well as sildenafil and statins therapy. Conversely, no significant differences were found in NIRS-2D values between different nailfold-videocapillaroscopy patterns.Conclusion
NIRS-2D imaging is a simple, automated tool to non-invasively detect regional microcirculatory impairment in SSc, which seems to add significant functional information to the morphological picture of nailfold-videocapillaroscopy. 相似文献86.
Chronic persistent Epstein-Barr virus infection of natural killer cells and B cells associated with granular lymphocytes expansion 总被引:1,自引:0,他引:1
Hirokazu Kanegane Taizo Wado Koji Nunogami Hidetoshi Seki Noboru Taniguchi & Giovanna Tosato 《British journal of haematology》1996,95(1):116-122
B lymphocytes and epithelial cells are the only cell types known to be infected with Epstein-Barr virus (EBV) in normal individuals. Rarely, EBV also infects other cells, including natural killer (NK) cells, almost always in the context of fatal leukaemias or lymphoproliferative disorders. We report on a 6-year-old previously healthy girl who developed fevers and liver function abnormalities for 3 months. The peripheral blood revealed an abnormal expansion of large granular lymphocytes, comprising 24% of the white blood cells. Flow cytometric analysis of the peripheral blood mononuclear cells showed an abnormal increase of CD16-positive NK cells, 62% of which were EBV-infected by in situ EBER-1 hybridization. The circulating B cells were normal in number, but 18% were infected with EBV by in situ EBER-1 hybridization. Approximately 2 years after resolution of all symptoms and continued good health, 35% of the circulating mononuclear cells were EBV-infected, indicative of persistent expansion of EBV-infected cells. We conclude that abnormal expansions of EBV-infected NK and B cells can be associated with a chronic benign course. 相似文献
87.
HIV-1 Tat enhances Kaposi sarcoma-associated herpesvirus (KSHV) infectivity 总被引:8,自引:1,他引:8 下载免费PDF全文
The high frequency of Kaposi sarcoma (KS) in immunodeficiency states, particularly in patients with AIDS, has been attributed to increased replication of KS-associated herpesvirus (KSHV), a necessary cofactor for KS development. However, experimental KSHV infection of endothelial lineage cells that compose KS lesions has been difficult even in the absence of immune cells. Here we show that HIV-1 Tat protein can directly promote KSHV transmission. Full-length HIV-1 Tat and a 13-amino-acid peptide corresponding to the basic region of Tat specifically enhances the entry of KSHV into endothelial and other cells, presenting evidence for an active role of HIV-1 in the development of KSHV-associated diseases. These results can explain why AIDS-KS is more frequent and clinically more aggressive than KS in other immunodeficiency states. 相似文献
88.
Monica Terenziani MD Paolo D'Angelo MD Alessandro Inserra MD Renata Boldrini MD Gianni Bisogno MD Gian Luca Babbo MD Massimo Conte MD Patrizia Dall' Igna MD Maria Debora De Pasquale MD Paolo Indolfi MD Luigi Piva MD Giovanna Riccipetitoni MD Fortunato Siracusa MD Filippo Spreafico MD Paolo Tamaro MD Giovanni Cecchetto MD 《Pediatric blood & cancer》2015,62(7):1202-1208
89.
Arianna Aprile Giovanna Palermo Antonio De Luca Roberta Pinalli Enrico Dalcanale Pasquale Pagliusi 《RSC advances》2018,8(29):16314
Reliable chemical sensors with high selectivity and sensitivity toward specific target molecules require rational synthesis of receptors, in-depth characterization of their complexation abilities and highly efficient transduction of the molecular recognition event. Here we report a steady-state and time-resolved fluorescence investigation of EtQxBox, a fluorescent conformationally blocked quinoxaline-based cavitand, aimed at assessing its selectivity toward aromatic versus non-aromatic analytes in solution. Fluorescence quenching of the EtQxBox in acetone is observed at increasing concentration of both aromatic (i.e. benzonitrile) and aliphatic (i.e. acetonitrile) compounds. The combination with fluorescence lifetime measurements permits to discriminate the predominantly static quenching of the aromatic analyte, due to non-fluorescent host–guest complex formation, from the mostly dynamic quenching of the non-aromatic compound, resulting from aspecific diffusive collisions between the fluorophore and the quencher. The equilibrium association constants for both the complexes have been estimated using Stern–Volmer model.We investigate the role of combined static and dynamic quenching in fluorescence transduction of benzonitrile and acetonitrile complexation by a rigid quinoxaline-based cavitand. 相似文献
90.
Ames Paul R. J. D’Andrea Giovanna Marottoli Vincenzo Arcaro Alessia Iannaccone Luigi Gentile Fabrizio Maraglione Maurizio 《Journal of thrombosis and thrombolysis》2022,54(2):330-338
Journal of Thrombosis and Thrombolysis - To compare age at 1st ischaemic stroke (IS) in a cohort of juvenile (<?46 years of age) IS patients evaluated for the rs1801133... 相似文献