全文获取类型
收费全文 | 12357篇 |
免费 | 609篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 177篇 |
儿科学 | 358篇 |
妇产科学 | 332篇 |
基础医学 | 1332篇 |
口腔科学 | 241篇 |
临床医学 | 975篇 |
内科学 | 3326篇 |
皮肤病学 | 102篇 |
神经病学 | 1192篇 |
特种医学 | 555篇 |
外国民族医学 | 4篇 |
外科学 | 1778篇 |
综合类 | 38篇 |
一般理论 | 3篇 |
预防医学 | 578篇 |
眼科学 | 171篇 |
药学 | 832篇 |
中国医学 | 26篇 |
肿瘤学 | 1035篇 |
出版年
2023年 | 73篇 |
2022年 | 191篇 |
2021年 | 337篇 |
2020年 | 185篇 |
2019年 | 295篇 |
2018年 | 364篇 |
2017年 | 278篇 |
2016年 | 290篇 |
2015年 | 346篇 |
2014年 | 441篇 |
2013年 | 551篇 |
2012年 | 885篇 |
2011年 | 872篇 |
2010年 | 466篇 |
2009年 | 473篇 |
2008年 | 730篇 |
2007年 | 720篇 |
2006年 | 700篇 |
2005年 | 702篇 |
2004年 | 631篇 |
2003年 | 588篇 |
2002年 | 541篇 |
2001年 | 195篇 |
2000年 | 162篇 |
1999年 | 174篇 |
1998年 | 112篇 |
1997年 | 114篇 |
1996年 | 95篇 |
1995年 | 82篇 |
1994年 | 72篇 |
1993年 | 52篇 |
1992年 | 110篇 |
1991年 | 92篇 |
1990年 | 90篇 |
1989年 | 76篇 |
1988年 | 90篇 |
1987年 | 81篇 |
1986年 | 74篇 |
1985年 | 63篇 |
1984年 | 46篇 |
1983年 | 49篇 |
1982年 | 39篇 |
1981年 | 44篇 |
1980年 | 32篇 |
1979年 | 45篇 |
1978年 | 27篇 |
1977年 | 23篇 |
1974年 | 29篇 |
1973年 | 23篇 |
1968年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The present experiments were performed to study the binding characteristics of delta opioid receptors in membrane preparations obtained from the brain of adult male rats, and to analyze whether aging modifies these binding parameters. The binding characteristics of delta opioid receptors were evaluated on membrane preparations derived from dissected brain regions (hypothalamus, amygdala, mesencephalon, corpus striatum, hippocampus, thalamus, frontal poles, anterior and posterior cortex) collected from male rats of 3 and 24 months of age; the highly selective ligand 3H-[D-Pen2-D-Pen5] enkephalin (3H-DPDPE) was used. The results obtained in young rats show that the distribution of delta opioid receptors is different in the various brain areas examined; these receptors appear to be maximally concentrated in the frontal poles, anterior and posterior cortex; lower concentrations were found in the other structures considered. Kd (dissociation constant) for the delta sites was found very similar in all areas. The distribution of delta opioid receptors in the brain of 24-month-old rats was similar to that observed in young animals; this result was surprising in view of the fact that aging modifies the number of other types of brain opioid receptors (mu and kappa). 相似文献
32.
R Vettor C Martini L Calò S Cantaro C Macor C De Palo N Sicolo C Scandellari G Federspil 《Diabète & métabolisme》1992,18(3):213-217
Anomalies in prostaglandin (PG) synthesis have been suggested in both experimental and human diabetes mellitus; increased levels of plasma and tissue eicosanoids has been recently reported by several investigators. One step in prostaglandin synthesis is the enzymatic hydrolysis of membrane phospholipids by Phospholipase A2 (PLA2). Nevertheless the alternative pathway involving Phospholipase C must be considered. An evaluation of PLA2 activity is therefore a useful method for studying prostaglandin synthesis in the peripheral target tissues of insulin activity. We studied PLA2 activity in normal and diabetic rat muscle. Streptozotocin-induced diabetic rats showed significantly higher muscular PLA2 activity when compared with controls (3.04 x 10(-2) +/- 0.50 x 10(-2) versus 1.34 x 10(-2) +/- 0.35 x 10(-2) arachidonic acid pMol.mg protein-1.min-1 (p less than 0.01). This effect was not observed in diabetic animals successfully treated with insulin (1.78 x 10(-2) +/- 0.5 x 10(-2) versus 1.34 x 10(-2) +/- 0.35 x 10(-2) arachidonic acid pMol.mg protein-1.min-1), and a significant correlation was found between blood glucose and muscular PLA2 activity (r = 0.42; p less than 0.05). Our results clearly show that in streptozotocin-induced diabetic rats muscular PLA2 activity is significantly higher. The relationship between blood glucose levels and muscular PLA2 activity and the decrease of PLA2 activity after insulin treatment suggest that these changes may be related to a defect in insulin effect. 相似文献
33.
Macrophage infiltration is frequent in the early stages of various proliferative eye disorders, including subretinal neovascularization. In this study, we set out to establish the origin of macrophages found in an animal model of laser-induced subretinal neovascularization. One primate received several intravenous injections of a colloidal carbon suspension. We then applied standard argon laser lesions to the retina of both eyes, which were enucleated eight days later and sectioned serially for histological examination. A quantitative estimate of carbon-laden and non-laden leukocytes was made based on morphological criteria. Mononuclear leukocytes accumulated in the laser lesions and the percentage of carbon-laden mononuclear leukocytes in relation to the total leukocyte number was higher in the extravascular area of the laser sites than in the systemic circulation. These findings indicate that the majority of mononuclear leukocytes that accumulate at the sites of laser lesions are derived from the systemic circulation. 相似文献
34.
Mitchel A Kling Salvatore Alesci Gyorgy Csako Rene Costello David A Luckenbaugh Omer Bonne Roman Duncko Wayne C Drevets Husseini K Manji Dennis S Charney Philip W Gold Alexander Neumeister 《Neuropsychopharmacology》2007,62(4):309-313
BACKGROUND: Major depressive disorder (MDD) shows increased coronary artery disease (CAD) risk of unknown mechanism(s). MDD is more common in women than men; CAD diagnosis can be difficult in women. Elevations of the inflammatory markers C-reactive protein (CRP) and serum amyloid A (SAA) predict increased CAD risk in populations; few data on these markers exist in MDD, particularly in remitted patients. METHODS: We measured fasting am serum CRP (high sensitivity, CRP(hs)) and SAA in 18 unmedicated, remitted women with MDD (mean age 41 +/- (SD)12, body mass index (BMI) 25.2 +/- 4.1 kg/m(2)) and 18 BMI-matched healthy control subjects (age 36 +/- 10, BMI 25.3 +/- 3.8 kg/m(2)) on 2 separate occasions, > or = 6 days apart. RESULTS: Repeat SAA and CRP(hs) measurements strongly correlated across study days (SAA: r = .83, p < .001; CRP(hs): r = .94, p < .001). Both SAA (5.30 +/- 3.39 vs. 2.84 +/- 1.87 mg/L, p < .005) and CRP(hs) (3.23 +/- 3.17 vs. 1.12 +/- 1.45 mg/L; p < .01) were significantly elevated in MDD women versus controls. CONCLUSIONS: Elevated SAA and CRP(hs) in remitted, unmedicated women with MDD indicate a pro-inflammatory state unrelated to current depressive symptoms or pharmacotherapy. These findings suggest that inflammatory mechanisms may in part underlie findings of increased CAD risk in MDD. 相似文献
35.
36.
Non-specific bronchial hyper-responsiveness in children with allergic rhinitis: Relationship with the atopic status 总被引:1,自引:0,他引:1
Giuseppina Cuttitta Fabio Cibella Stefania La Grutta Maria R. Hopps Salvatore Bucchieri Giovanni Passalacqua Giovanni Bonsignore 《Pediatric allergy and immunology》2003,14(6):458-463
An increased prevalence of bronchial hyper-responsiveness (BHR) has been demonstrated in children from a general population, and in non-asthmatic adults with allergic rhinitis. Thus, also children with allergic rhinitis are expected to be at higher risk of BHR. We evaluated the prevalence of BHR in a sample of non-asthmatic children with allergic rhinitis by means of the methacholine (Mch) bronchial challenge, and by monitorizing the airway patency using the daily peak expiratory flow variability (PEFv). Fifty-one children (ranged 6–15 years of age) with allergic rhinitis, ascertained by skin prick test to inhalant allergens, underwent a 14-day peak expiratory flow monitoring, and a Mch bronchial provocation challenge. Thirty healthy children matched for age, and sex served as control group. Thirty-one children in the rhinitis group (61%), and six (20%) in the control group were Mch+ (Mch provocative dose causing a 20% fall of forced expiratory volume in 1 s respect to baseline <2250 μ g, equivalent to 11.50 μ mol). In rhinitic children the PEFv did not significantly differ between Mch+ and Mch− subjects, but the total serum immunoglobulin E (IgE) were higher among Mch+. The persistent form of rhinitis was significantly associated to Mch positivity. Non-asthmatic children with allergic rhinitis displayed a high prevalence of BHR. The BHR was significantly associated with persistent rhinitis and with higher total IgE levels. Nevertheless, the spontaneous changes in airway patency, as expressed by PEFv, were within normal limits both in Mch+ and Mch− children. 相似文献
37.
Vito Briganti Lucia Oriolo Vitaliano Buffa Salvatore Garofalo Sebastiano Cavallaro Alessandro Calisti 《European journal of cardio-thoracic surgery》2005,28(1):11-15
OBJECTIVE: A Tracheomalacia complicates 11-33% of cases of Oesophageal Atresia with distal Tracheo-Oesophageal Fistula. The lesion generally involves only the thoracic segment of the trachea, and it has close anatomical relationships with the mediastinal structures, specially with the aortic arch. We therefore tried to define the most important morphotypes of tracheobronchial malacia by using dynamic fiberoptic bronchoscopy (DFB) and spiral multilayer computed tomography (CT). METHODS: Between 1999 and 2003 we studied 40 children from two different institutions who had been operated on at birth for oesophageal atresia. All patients were been submitted to DFB, and the positive cases underwent examination by CT with an iodinated contrast medium. CT angiographic images of great vessels and multiplanar and three-dimensional images of the airways (virtual broncoscopy and broncography) were obtained for morphological evaluation. RESULTS: Twenty-five patients (62%) tested positive for malacia using DBF and all were also confirmed by CT study. In 11 cases (46%), the malacia was located at the thoracic section of the trachea, which was occluded by compression of the aorto-innominate complex. A simple intrinsic tracheomalacia without any vascular compression was present in eight cases (33%), while in five cases (21%), the malacia was complex. CONCLUSIONS: A correct morphological analysis of the malformed segment permitted 'tailored surgery' for each individual patient, allowing us to take account of the type of malacia, its length, and the compressive action exercised by the mediastinal great vessels. 相似文献
38.
Giovanni Scambia MD Elvira Foti MD Gabriella Ferrrandina MD Francesco P. Leone MD Angiolo Gadducci MD Pierluigi Benedetti-Panici MD Salvatore Mancuso MD 《American journal of obstetrics and gynecology》1996,175(6):1606-1610
OBJECTIVE: Our purpose was to investigate immunosuppressive acidic protein in the prognostic characterization of advanced ovarian cancer. STUDY DESIGN: Serum levels of immunosuppressive protein were prospectively measured in 80 patients with untreated ovarian carcinoma. To evaluate the prognostic significance of immunosuppressive acidic protein levels, cutoff points were studied every 50 μg/ml between 450 and 1350 μg/ml. RESULTS: Pretreatment immunosuppressive acidic protein levels were not significantly associated with stage, histotype, grade of differentiation, postoperative residual tumor, and response to chemotherapy. The most significant association with survival was observed at a cutoff value of 1100 μg/ml (p = 0.0089). In the univariate analysis for overall survival, International Federation of Gynecology and Obstetrics stage and immunosuppressive acidic protein status were found to have a role in predicting ovarian cancer prognosis. In the multivariate analysis only immunosuppressive acidic protein status was significantly associated with survival. A statistical correlation was found between serum levels and overall survival (p = 0.0104, χ2 6.56), including immunosuppressive acidic protein as a continuous variable. CONCLUSION: Our data suggest that immunosuppressive acidic protein assay is a potentially useful tool in the prognostic characterization of advanced ovarian cancer. (Am J Obstet Gynecol 1996;175:1606-10.) 相似文献
39.
Giovanni Manfredi Tuan Vu Eduardo Bonilla Eric A. Schon Salvatore DiMauro Enrica Arnaudo Lee Zhang Lewis P. Rowland Michio Hirano 《Annals of neurology》1997,42(2):180-188
We identified large-scale heteroplasmic mitochondrial DNA (mtDNA) rearrangements in a 50–year-old woman with an adult-onset progressive myopathy. The predominant mtDNA abnormality was a 21.2–kb duplicated molecule. In addition, a small population of the corresponding partially deleted 4.6–kb molecule was detected. Skeletal muscle histology revealed fibers that were negative for cytochrome c oxidase (COX) activity and had reduced mtDNA-encoded COX subunits. By single-fiber polymerase chain reaction analysis, COX-negative fibers contained a low number of wild-type or duplicated mtDNA molecules (ie, nondeleted). In situ hybridization demonstrated that the abnormal fibers contained increased amounts of mtDNA compared with normal fibers and that most of the genomes were deleted. We concluded that deleted mtDNA molecules were primarily responsible for the phenotype in this patient. 相似文献