全文获取类型
收费全文 | 38452篇 |
免费 | 2081篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 400篇 |
儿科学 | 1180篇 |
妇产科学 | 824篇 |
基础医学 | 5911篇 |
口腔科学 | 283篇 |
临床医学 | 3434篇 |
内科学 | 9197篇 |
皮肤病学 | 882篇 |
神经病学 | 3603篇 |
特种医学 | 1128篇 |
外国民族医学 | 31篇 |
外科学 | 4687篇 |
综合类 | 81篇 |
一般理论 | 6篇 |
预防医学 | 2742篇 |
眼科学 | 626篇 |
药学 | 2557篇 |
中国医学 | 74篇 |
肿瘤学 | 2944篇 |
出版年
2023年 | 202篇 |
2022年 | 131篇 |
2021年 | 524篇 |
2020年 | 314篇 |
2019年 | 587篇 |
2018年 | 1082篇 |
2017年 | 769篇 |
2016年 | 732篇 |
2015年 | 911篇 |
2014年 | 923篇 |
2013年 | 1491篇 |
2012年 | 2622篇 |
2011年 | 2585篇 |
2010年 | 1220篇 |
2009年 | 967篇 |
2008年 | 2383篇 |
2007年 | 2457篇 |
2006年 | 2322篇 |
2005年 | 2386篇 |
2004年 | 2320篇 |
2003年 | 2112篇 |
2002年 | 2058篇 |
2001年 | 1056篇 |
2000年 | 1131篇 |
1999年 | 896篇 |
1998年 | 187篇 |
1997年 | 131篇 |
1996年 | 137篇 |
1995年 | 133篇 |
1994年 | 110篇 |
1992年 | 522篇 |
1991年 | 464篇 |
1990年 | 461篇 |
1989年 | 431篇 |
1988年 | 390篇 |
1987年 | 378篇 |
1986年 | 339篇 |
1985年 | 319篇 |
1984年 | 232篇 |
1983年 | 179篇 |
1982年 | 104篇 |
1979年 | 157篇 |
1974年 | 118篇 |
1973年 | 106篇 |
1972年 | 109篇 |
1971年 | 114篇 |
1970年 | 106篇 |
1969年 | 129篇 |
1968年 | 110篇 |
1967年 | 103篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Véronique Strijckmans Michel Bottlaender Humin Luo Michèle Ottavianil Daniel W. McPherson Christian Loc'h Chantal Fuseau Furn F. Knapp Bernard Mazière 《European journal of nuclear medicine and molecular imaging》1997,24(5):475-482
We studied the potential of three radiobrominated isomers of BrQNP, (Z(-,-)-[76Br]BrQNP,E(-,-)-[76Br]BrQNP andE(-,+)-[76Br]BrQNP), as suitable radioligands for imaging of central muscarinic cholinergic receptors in the human brain. These radioligands were stereospecifically prepared by electrophilic radiobromodestannylation of the respective tributylstannyl precursors using no-carrier-added [76Br]BrNH4 and peracetic acid. Preliminary pharmacological characterizations were determined by biodistribution, autoradiography, competition, displacement and metabolite studies in rats. The (-,-)-configuration presented important specific uptakes in brain muscarinic cholinergic receptor (mAChR)-rich structures and in heart, low metabolization rates and an apparent M2 selectivity. The (-,+)-configuration revealed more rapid clearance, lower uptake, a higher metabolization rate and an apparent M1 selectivity. Reversibility of the binding was confirmed for the three radiotracers. Positron emission tomography in the living baboon brain revealed high and rapid uptake in the brain and accumulation in the mAChR-rich structures studied. At 30 min p.i., theE(-,-)-radiotracer reached a plateau in cortex, pons and thalamus with concentrations of 29%, 24% and 19% ID/l, respectively.Z(-,-)-[76Br]BrQNP also accumulated in these structures, reaching a maximal uptake (27% ID/l) in the cortex 2 h p.i. At 5 min p.i. a plateau (17% ID/l) was only observed in the cortex for theE(-,+)-[76Br]BrQNP; by contrast, the other structures showed slow washout. After 3 weeks, the (-,-)-radiotracers were studied in the same baboon pretreated with dexetimide (1 mg/kg), a well-known muscarinic antagonist. In all the mAChR structures, the highly reduced uptake observed after this preloading step indicates that these radiotracers specifically bind to muscarinic receptors.Z(-,-)-[76Br]BrQNP, which is displaced in higher amounts from M2 mAChR-enriched structures, reveals an M2 affinity. The two isomers having the (-,-)-configuration are potential probes for investigating central muscarinic receptors. The absolute configuration on the acetate chiral centre influences their muscarinic subtype selectivity and thecis-trans isomerism of the vinyl moiety affects their specific fixation. 相似文献
72.
C. H. van der Meyden J. F. K. de Villiers B. D. Middlecote J. Terblanchè 《Neuroradiology》1994,36(3):221-223
A 9-year-old boy presented with a subacute history of optic neuritis followed by brainstem involvement, with fever and a lymphocytic pleocytosis in the cerebrospinal fluid. Gadolinium-enhancing ring lesions were demonstrate in the white matter of the cerebrum, brainstem and cerebellum on day 17 of the illness, all appearing simultaneously as part of a monophasic illness. A parietal lesion exerted mass effect. Needling and biopsy yielded no evidence of a pyogenic lesion, tumour or tuberculosis and showed vasculitis. There was insufficient material for myelin staining. Dexamethasone therapy lead to rapid improvement of the radiological lesions: MRI and CT on day 34 of the illness showed complete clearing of the lesions except for residual abnormality at the biopsy site. 相似文献
73.
D Labbé E Kaluzinski J Y Ferrand A Dompmartin J F Compère 《Revue de stomatologie et de chirurgie maxillo-faciale》1991,92(6):402-405
After briefly summing up the nosology of rhinophyma, the authors report their experience with the surgical correction of this nasal disease, on the basis of eight cases. They explain their reasons for giving up dermasection and preferring dermabrasion. 相似文献
74.
75.
76.
77.
Luciano Baresi Fabrizio Consorti Manuele Di Paola Antonio Gargiulo Mauro Pezzè 《Journal of medical systems》1997,21(6):369-388
The quality of health care systems and processes is becoming a prominent problem and more and more efforts are devoted to define methodologies and tools to measure and assure quality of care. New methods are required to optimize health care processes to guarantee high quality standards within (limited) available resources. Resource optimizations able to preserve the quality of treatments require good models of medical processes. This paper presents LEMMA, a new notation to model medical processes. LEMMA provides physicians with intuitive graphical elements to design their models. At the same time a high level timed Petri net corresponding to the designed model is built automatically. In this way, LEMMA models are ascribed formal semantics and can be executed and analyzed automatically. The dual language approach followed in this paper allows physicians to gain all the benefits of formal methods without being proficient in them. Medical users manage simple graphical elements, while Petri nets ensure formality and validation capabilities. In this way LEMMA mixes formal and informal notations, overcoming the problems of both the approaches. The definition of the notation has been supported by the development of an environment to design LEMMA models. The environment, besides letting us experiment with the notation, has been employed to define and analyze real case studies. 相似文献
78.
79.
Francoise Mouchet Valérie Hansen Inge Van Herreweghe Olivier Vandenberg Régine Van Hesse Michèle Gérard Michèle Toppet Maryse Wanlin Véronique Toppet Georges Casimir Dominique Haumont Jack Levy 《Infection control and hospital epidemiology》2004,25(12):1062-1066
OBJECTIVE: To assess the extent of nosocomial transmission of tuberculosis among infants, family members, and healthcare workers (HCWs) who were exposed to a 29-week-old premature infant with congenital tuberculosis, diagnosed at 102 days of age. DESIGN: A prospective exposure investigation using tuberculin skin test (IST conversion was conducted. Contacts underwent two skin tests 10 to 12 weeks apart. Clinical examination and chest radiographs were performed to rule out disease. Isoniazid prophylaxis was administered to exposed infants at higher risk. SETTING: A neonatal intensive care unit in an urban hospital in Brussels, Belgium. PARTICIPANTS: Ninety-seven infants, 139 HCWs, and 180 visitors. RESULTS: Newly positive TST results occurred in HCWs who had been in close contact with the infant. Six (19%) of 32 primary care nurses and physicians had TST conversions and received treatment. Among the 97 exposed infants, 85 were screened and 34 were identified as at higher risk of infection. Of these, 27 received preventive isoniazid. None of the infants and none of the 93 other infants' family members evaluated were infected. CONCLUSIONS: Congenital tuberculosis in an infant poses a risk for nosocomial transmission to HCWs. Delayed diagnosis of this rare disease and close proximity are the most important factors related to transmission. 相似文献
80.
A. Jouvet E. Derrington J. Pialat C. Lapras M. Fèvre-Montange R. Besançon M. F. Belin G. Saint-Pierre 《Acta neuropathologica》1994,88(4):334-348
We have studied 20 pineal parenchymal tumors (PPT) and 4 normal or cystic pineal glands both by light and electron microscopy and immunohistochemistry with antibodies against glial markers [glial fibrillary acidic protein (GFAP) and protein S-100] or neural/neuroendocrine markers [neurofilaments (NF), synaptophysin and chromogranin A]. Light microscopy revealed the cellular organization of pinealocytes in the normal gland and in different morphological types of pineal tumors (typical pineocytomas, PPT with intermediate differentiation, mixed PPT exhibiting elements of both pineocytoma and pineoblastoma and pineoblastomas). Immunohistochemistry showed the presence of GFAP and protein S-100 in interstitial cells in nonneoplastic pineal gland. Cell processes were labeled with anti-synaptophysin and anti-NF antibodies. No immunoreactivity was found for chromogranin A in non-neoplastic pineal gland. In pineocytomas, GFAP and protein S-100 were observed in interstitial cells. Synaptophysin and NF were present in the large rosettes of pineocytomas. Synaptophysin, NF and chromogranin A were present in pineocytomas with a lobular arrangement of cells. Anti-chromogranin A immuno-reactivity was also seen in lobular areas of some PPT with intermediate differentiation. Analysis of normal human pineal gland by electron microscopy showed the presence of vesicle-crowned rodlets (VCR or synaptic ribbons), fibrous filaments (F), paired twisted filaments but few dense-core vesicles (DCV) in normal pinealocytes. Tumoral pineal cells appeared to differentiate either towards a neurosensory pathway characterized by the presence of sensory cells elements (VCR and F), or towards a neuroendocrine pathway, with the occurrence of many DCV. Immunogold labeling demonstrated the presence of chromogranin A in neurosecretory granules.Supported by grants from the Région Rhône Alpes and from INSERM (CJF 90-10) 相似文献