全文获取类型
收费全文 | 1352224篇 |
免费 | 101193篇 |
国内免费 | 1922篇 |
专业分类
耳鼻咽喉 | 17342篇 |
儿科学 | 43200篇 |
妇产科学 | 36364篇 |
基础医学 | 201668篇 |
口腔科学 | 36705篇 |
临床医学 | 126926篇 |
内科学 | 266154篇 |
皮肤病学 | 28883篇 |
神经病学 | 111374篇 |
特种医学 | 50389篇 |
外国民族医学 | 270篇 |
外科学 | 191203篇 |
综合类 | 26804篇 |
现状与发展 | 3篇 |
一般理论 | 639篇 |
预防医学 | 111671篇 |
眼科学 | 29580篇 |
药学 | 98579篇 |
7篇 | |
中国医学 | 2108篇 |
肿瘤学 | 75470篇 |
出版年
2021年 | 11336篇 |
2019年 | 11760篇 |
2018年 | 15664篇 |
2017年 | 11978篇 |
2016年 | 13252篇 |
2015年 | 15249篇 |
2014年 | 20884篇 |
2013年 | 31289篇 |
2012年 | 43357篇 |
2011年 | 45820篇 |
2010年 | 26548篇 |
2009年 | 25417篇 |
2008年 | 42916篇 |
2007年 | 45948篇 |
2006年 | 45179篇 |
2005年 | 44234篇 |
2004年 | 42374篇 |
2003年 | 40287篇 |
2002年 | 39134篇 |
2001年 | 57488篇 |
2000年 | 58413篇 |
1999年 | 49404篇 |
1998年 | 14455篇 |
1997年 | 13070篇 |
1996年 | 13338篇 |
1995年 | 12616篇 |
1994年 | 11688篇 |
1992年 | 39104篇 |
1991年 | 38516篇 |
1990年 | 37219篇 |
1989年 | 36004篇 |
1988年 | 33364篇 |
1987年 | 32674篇 |
1986年 | 31186篇 |
1985年 | 29455篇 |
1984年 | 22476篇 |
1983年 | 19660篇 |
1982年 | 11814篇 |
1979年 | 21343篇 |
1978年 | 15729篇 |
1977年 | 13084篇 |
1976年 | 12083篇 |
1975年 | 13079篇 |
1974年 | 15879篇 |
1973年 | 15638篇 |
1972年 | 14775篇 |
1971年 | 13751篇 |
1970年 | 13011篇 |
1969年 | 12289篇 |
1968年 | 11395篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
summary The aetiology of denture stomatitis is not clear from the literature. Some studies show its aetiology as Candida albicans, while other reports point out the significance of microorganisms. In this study the existence of C. albicans and microorganisms was investigated in subjects with and without denture stomatitis. The results showed that a combination of C. albicans and microorganisms is more likely to be responsible for denture stomatitis. 相似文献
72.
Piecewise constant incidence models were developed to estimate the force of infection in women from age-and time-specific antenatal or neonatal seroprevalence data. Differential inclusion of infected women in sero-surveys compared to uninfected women was taken into account, with respect to both changes in inclusion rate following infection, and changes in relative inclusion rate over calendar time. These models were applied to anonymous HIV seroprevalence data collected from neonates born to black and Hispanic women in New York City 1988-1992, with incidence and fertility parameters estimated by maximum likelihood. Estimates of inclusion rate parameters accorded well with what is known about the natural history of HIV. The data could not distinguish between additive and multiplicative combination of the effects of age and time on incidence. Incidence was strongly dependent on age with the highest incidence in women aged 20-34 years. There was strong evidence that incidence had been falling in Hispanic women since 1982-1984. The results illustrate the extent to which trends in incidence over time may be confounded by changes in the relative inclusion rate of infected and uninfected women. 相似文献
73.
74.
Brahma.S. Sharma Supryia Mhaskar Louisa Balazs Martin Siaw 《Immunopharmacology and immunotoxicology》1992,14(1):1-19
We reported recently that a novel immunomodulator, 7-thia-8-oxoguanosine (7T80G)2 inhibited formation of pulmonary melanoma metastases (1), prevented against viral infection in mice (2) and potentiated the efficacy of a weakly immunogenic leukemia vaccine (3). Since certain tumor metastases and virus infected cells are targets to natural killer cells (NK cells), we now investigated whether 7T80G is capable of activating NK cells in mice using NK cell sensitive YAC-1 and B16 and NK cell insensitive P815 targets. CBA/CaJ spleen cells incubated in vitro with 7T80G at concentrations ranging from 0.005 to 0.5 mM responded with increased NK cell activity (32-62 %) compared to controls (4-8%) to YAC-1 targets. Similar levels of augmentation in NK cell activity were observed when 40-168 mg/kg of 7T80G was administered in vivo. In addition to the spleen, 7T80G activated NK cells in the bone marrow (BM), the lungs, the liver, and in peritoneal exudate cells (PE). Although 7T80G elicited activation of NK cells was observed as early as three hours after treatment, the maximal activity was observed after 24 h in the spleen; 12 h in the BM; 48 h in the lungs, and 72 h in PE. Administration of the drug by s.c, i.v., and i.p. routes all induced activition of NK cells in spleen, BM and PE. 7T80G was found to activate NK cells in seven inbred and an outbred mouse strain, suggesting that the induced cytotoxicity against allogeneic and syngeneic tumor cells is not strain specific as well as independent of MHC restriction. C3H/He, CBA/CaJ and BDF/1 displayed higher levels of increased NK cell activity, whereas AKR mice were low responders. Low concentrations of IL-2 (0.25-5 U/ml) that induce little or no NK cell activity, when used in combination with 7T80G, elicited significant enhancement of NK cell cytotoxicity. In contrast, IFN and 7T80G showed no such synergism. 相似文献
75.
Although malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of adult life, it is fairly rare in the head and neck region (3-6%). Between 1983 and 1991 8 patients with MFH in the head and neck region have been observed and treated at the ENT-department of the University of Tübingen. 5 patients have been operated (laryngopharyngeal localization), 2 patients underwent irradiation (unresectable fast growing T4-tumors of the pharynx and thyroid) and one female patient refused further therapy after two resections elsewhere. Operated patients showed no evidence of disease 2-8 years after resection (all margins have been controlled histologically). Both irradiated patients died 4 respectively 2 months after full (70 Gy) and incomplete (17 Gy) radiotherapy without visible positive effects. Both patients developed pulmonary metastasis. Since MFH can grow in thin layers along musculaoponeurotic structures the exact size is not always demonstrable by ultrasound, CT or MR scans. Metastasis occur in up to 40%, preferentially in regionary lymph nodes, in lung, liver and skeletal system. These phenomenon requires a full pretherapeutic staging. Histologically MFH is sometimes hard to distinguish from other tumors as for example various sarcomas and pleomorphic carcinoma. Therefore, immunohistochemical (mesenchymal markers) and electron microscopical investigations are advised. Resection with exact histological controll of all margins is the therapy of choice. We experienced that laryngeal MFH (n = 3) can be resected without laryngectomy under certain circumstances. Although unsuccessfull in our two cases, according to the literature, radiotherapy should be administered in unresectable cases. Depending on localization and size of MFH long survival, in single cases healing, of this disease is possible by surgical treatment. 相似文献
76.
Of 431 patients with gastric cancer observed in our institution, 23 (5.3%) had early gastric cancer (EGC). Macroscopic presentation, histology, depth of invasion, and lymph node involvement were evaluated in all the cases. All patients underwent surgery and an intensive follow-up was performed. Five of the 23 patients progressed, and the risk factors were examined. Histology seemed to be the main prognostic factor in our study, since intestinal type of EGC was associated to a significantly better prognosis. Total gastrectomy is indicated in the proximal localization of EGC, and should perhaps be performed also in cases presenting undifferentiated histology. 相似文献
77.
Premalignant lesions and nonsquamous malignancy of the penis and carcinoma of the scrotum. 总被引:2,自引:0,他引:2
P F Schellhammer G H Jordan E L Robey J T Spaulding 《The Urologic clinics of North America》1992,19(1):131-142
Premalignant lesions of the penis include cutaneous horn, balanitis xerotica obliterans, and leukoplakia. The true incidence of progression of each of these to squamous-cell carcinoma is unknown. Bowenoid papulosis, erythroplasia of Queyrat, and Bowen's disease are histologically identical to in situ carcinoma. Although the first is consistently benign, the latter two regularly evolve into invasive cancer. Malignant scrotal lesions include squamous-cell carcinoma, liposarcoma, leiomyosarcoma, basal-cell carcinoma, extramammary Paget's disease, erythroplasia of Queyrat, malignant melanoma, and metastases. Hemangioma can be confused with carcinoma. 相似文献
78.
79.
80.
Three hundred and twenty samples of subgingival plaque were obtained from 80 caucasian girls, ranging from 10 to 13 years of age. The samples were analyzed to verify the influence of age upon colonization of the gingival sulcus by microorganisms potentially pathogenic to the periodontal tissues. The gingival and plaque status were evaluated through the gingival index (GI) and plaque index (PlI) and the microflora was assessed by the enzymatic method benzoyl-arginine-naphthylamide (BANA). The results of the BANA test were positive for 62.50% of the tested individuals and 40% of the examined sites. The influence of age was statistically significant on BANA reactivity, and the number of positive sites was greater at 11 (57.5%) than at 12 years (28.8%). 相似文献