全文获取类型
收费全文 | 3378991篇 |
免费 | 268800篇 |
国内免费 | 6053篇 |
专业分类
耳鼻咽喉 | 48588篇 |
儿科学 | 107697篇 |
妇产科学 | 93202篇 |
基础医学 | 475913篇 |
口腔科学 | 99516篇 |
临床医学 | 307474篇 |
内科学 | 654193篇 |
皮肤病学 | 70445篇 |
神经病学 | 281181篇 |
特种医学 | 134634篇 |
外国民族医学 | 1247篇 |
外科学 | 507651篇 |
综合类 | 83064篇 |
现状与发展 | 4篇 |
一般理论 | 1431篇 |
预防医学 | 272881篇 |
眼科学 | 79866篇 |
药学 | 252726篇 |
7篇 | |
中国医学 | 6254篇 |
肿瘤学 | 175870篇 |
出版年
2018年 | 33753篇 |
2016年 | 29000篇 |
2015年 | 33135篇 |
2014年 | 47081篇 |
2013年 | 71977篇 |
2012年 | 96763篇 |
2011年 | 102355篇 |
2010年 | 60471篇 |
2009年 | 57699篇 |
2008年 | 97420篇 |
2007年 | 103197篇 |
2006年 | 104339篇 |
2005年 | 101442篇 |
2004年 | 98448篇 |
2003年 | 94765篇 |
2002年 | 93546篇 |
2001年 | 153660篇 |
2000年 | 159101篇 |
1999年 | 135109篇 |
1998年 | 39210篇 |
1997年 | 35554篇 |
1996年 | 35055篇 |
1995年 | 34001篇 |
1994年 | 31990篇 |
1993年 | 29907篇 |
1992年 | 109781篇 |
1991年 | 106153篇 |
1990年 | 103020篇 |
1989年 | 99544篇 |
1988年 | 92519篇 |
1987年 | 91287篇 |
1986年 | 86689篇 |
1985年 | 83124篇 |
1984年 | 63057篇 |
1983年 | 54133篇 |
1982年 | 32714篇 |
1981年 | 29213篇 |
1980年 | 27524篇 |
1979年 | 59874篇 |
1978年 | 42132篇 |
1977年 | 35552篇 |
1976年 | 33340篇 |
1975年 | 35293篇 |
1974年 | 43523篇 |
1973年 | 41572篇 |
1972年 | 38740篇 |
1971年 | 36061篇 |
1970年 | 33676篇 |
1969年 | 31436篇 |
1968年 | 28682篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
C. Oprea P.J. Szalanski M.V. Gustova I.A. Oprea V. Buzguta 《Applied radiation and isotopes》2009,67(12):2142-2145
R-mode factor analysis was applied to characterize the chemical composition of human teeth investigated by particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and X-ray fluorescence (XRF) techniques. The approach developed in this study enabled the separation between essential mineral teeth components and the pollutants deposited in teeth tissues during the human life. The three independent sources of metals incorporated in human teeth were found. The first source, representing about 43% of the variance of the concentration data, was characterized by pollutant elements of power industry emissions. The second factor was loaded with toxic elements of general urban pollution. The third factor represented the tooth source as it contained mainly large fractions of the mineral components of the tooth tissue as Ca and K. 相似文献
994.
995.
Stephen H. Olsen Linglei Ma Bertram Schnitzer Douglas R. Fullen 《Journal of cutaneous pathology》2009,36(3):302-307
Background: Clusterin is a ubiquitous 80 kDa heterodimeric glycoprotein previously shown to be expressed on tumor cells of systemic and, to a lesser extent, primary cutaneous anaplastic large cell lymphoma (PC-ALCL). Lymphomatoid papulosis (LyP), an important differential diagnosis of ALCL, has been studied for clusterin expression in only a small number of cases. The aim of this study was to compare clusterin immunostaining patterns in LyP and other cutaneous histologic simulants with those of PC-ALCL.
Methods: Formalin-fixed, paraffin-embedded sections of PC-ALCL (6), LyP (20), mycosis fungoides with large cell transformation (MF-LCT, 12), pityriasis lichenoides et varioliformis acuta (PLEVA, 12), arthropod bite reaction (ABR, 12) and lymphomatoid reactions (LR, 9) were immunostained for clusterin and evaluated for staining pattern and distribution. All diagnoses were made with clinicopathologic correlation.
Results: Characteristic dot-like Golgi staining was identified in 10/20 LyP (50%), 4/6 PC-ALCL (67%) and 9/12 MF-LCT (75%). Two of 12 PLEVA (17%), 1 of 12 ABR (8%) and 2 of 8 LR (25%) had lymphocytes (< 25%) with diffuse cytoplasmic staining. Dermal dendritic cells stained strongly for clusterin. High background staining occurred in some cases.
Conclusion: Clusterin immunostaining does not reliably distinguish between LyP, PC-ALCL or MF-LCT, but could distinguish LyP from its reactive histologic simulants. 相似文献
Methods: Formalin-fixed, paraffin-embedded sections of PC-ALCL (6), LyP (20), mycosis fungoides with large cell transformation (MF-LCT, 12), pityriasis lichenoides et varioliformis acuta (PLEVA, 12), arthropod bite reaction (ABR, 12) and lymphomatoid reactions (LR, 9) were immunostained for clusterin and evaluated for staining pattern and distribution. All diagnoses were made with clinicopathologic correlation.
Results: Characteristic dot-like Golgi staining was identified in 10/20 LyP (50%), 4/6 PC-ALCL (67%) and 9/12 MF-LCT (75%). Two of 12 PLEVA (17%), 1 of 12 ABR (8%) and 2 of 8 LR (25%) had lymphocytes (< 25%) with diffuse cytoplasmic staining. Dermal dendritic cells stained strongly for clusterin. High background staining occurred in some cases.
Conclusion: Clusterin immunostaining does not reliably distinguish between LyP, PC-ALCL or MF-LCT, but could distinguish LyP from its reactive histologic simulants. 相似文献
996.
E. González-Guerra M. R. Haro M. C. Fariña L. Martín L. Manzarbeitia L. Requena 《Clinical and experimental dermatology》2009,34(7):800-803
Glomeruloid haemangioma is considered a specific marker of POEMS ( p olyneuropathy, o rganomegaly, e ndocrinopathy, M -protein and s kin changes) syndrome and it is usually but not always associated with multicentric Castleman's disease. We report a 78-year-old man who presented with a single, red-violet soft nodule with superficial telangiectases on the scalp. Histopathologically, the lesion consisted of lobules of coiled aggregated capillaries that involved the lumina of dilated vascular structures, mimicking renal glomeruli. A collagenous stroma separated the capillary lobules, and eosinophilic, periodic-acid–Schiff positive globules of varying sizes and shapes were seen within the cytoplasm of endothelial cells. Immunohistochemical studies with antibodies against IgA and IgG, and against the kappa and lambda light chains of immunoglobulins showed immunoreactivity within the eosinophilic globules. Results of complete blood count, liver, renal and thyroid function tests, fasting blood sugar measurement, serum levels of oestradiol, testosterone, prolactin and cortisol, serum protein electrophoresis, immunoelectrophoresis and immunofixation yielded normal or negative results. No Bence–Jones proteinuria was found in a sample from a 24-h urine collection. To our knowledge, only two cases of glomeruloid haemangioma have been previously reported in patients without POEMS syndrome. We describe the third case of glomeruloid haemangioma in a patient without features of POEMS syndrome. 相似文献
997.
L.J. Mackintosh† M.N.C. de Koning‡ W.G.V. Quint‡ J. ter Schegget‡ I.M. Morgan R.M. Herd† M.S. Campo 《The British journal of dermatology》2009,161(1):56-62
Background Nonmelanoma skin cancer (NMSC) has been linked to cutaneous human papillomaviruses of the genus beta (betaPV).
Objectives We sought to assess the presence of betaPV in NMSC biopsies from a group of Scottish skin cancer patients, both immunocompetent (IC) patients and immunosuppressed (IS) organ transplant recipients.
Methods One hundred and twenty-one paraffin-embedded skin tumours (27 actinic keratosis, 41 intraepidermal carcinoma, 53 squamous cell carcinoma) and 11 normal skin samples were analysed for the presence of betaPV by a polymerase chain reaction–reverse hybridization assay designed to detect the presence of the 25 known betaPV genotypes.
Results In IC patients, betaPV was detected in 30 of 59 (51%) tumours and two of 11 (18%) normal skin samples ( P = 0·046). In IS patients, betaPV was found in 27 of 62 (44%) tumours; no normal skin samples were available for comparison. The most frequently found genotypes were HPV-24, HPV-15 and HPV-38. Of those tumours infected with betaPV, 28 of 57 (49%) were infected with more than one genotype (range 2–8). Tumours from IS patients were from a younger age group (mean age 57·4 years) than IC patients (mean age 73·8 years). Multiple infections were more common in tumours from IC patients (21 of 30; 70%) compared with those from IS patients (seven of 27; 26%) ( P < 0·001). In the IC group, age did not appear to influence the distribution of single and multiple infections whereas in IS patients the proportion of multiple infections to single infections increased with age. There were no multiple infections in normal skin.
Conclusions A wide spectrum of betaPV types was detected in our samples. Further characterization of betaPV in vivo is needed in order to determine the mechanisms by which the virus contributes to cutaneous carcinogenesis. 相似文献
Objectives We sought to assess the presence of betaPV in NMSC biopsies from a group of Scottish skin cancer patients, both immunocompetent (IC) patients and immunosuppressed (IS) organ transplant recipients.
Methods One hundred and twenty-one paraffin-embedded skin tumours (27 actinic keratosis, 41 intraepidermal carcinoma, 53 squamous cell carcinoma) and 11 normal skin samples were analysed for the presence of betaPV by a polymerase chain reaction–reverse hybridization assay designed to detect the presence of the 25 known betaPV genotypes.
Results In IC patients, betaPV was detected in 30 of 59 (51%) tumours and two of 11 (18%) normal skin samples ( P = 0·046). In IS patients, betaPV was found in 27 of 62 (44%) tumours; no normal skin samples were available for comparison. The most frequently found genotypes were HPV-24, HPV-15 and HPV-38. Of those tumours infected with betaPV, 28 of 57 (49%) were infected with more than one genotype (range 2–8). Tumours from IS patients were from a younger age group (mean age 57·4 years) than IC patients (mean age 73·8 years). Multiple infections were more common in tumours from IC patients (21 of 30; 70%) compared with those from IS patients (seven of 27; 26%) ( P < 0·001). In the IC group, age did not appear to influence the distribution of single and multiple infections whereas in IS patients the proportion of multiple infections to single infections increased with age. There were no multiple infections in normal skin.
Conclusions A wide spectrum of betaPV types was detected in our samples. Further characterization of betaPV in vivo is needed in order to determine the mechanisms by which the virus contributes to cutaneous carcinogenesis. 相似文献
998.
Abstract: Background: The identification of an autoimmune mechanism for many patients with chronic idiopathic urticaria (CIU) was used as a rational for a controlled clinical trial of cyclosporine for adults with CIU not responsive to usual measures. That randomized placebo controlled clinical trial demonstrated clinical efficacy, acceptable safety, and a suggestion of inducing remission in such patients. Objective: To report our experience with cyclosporine in pediatric patients with CIU. Methods: Fifty‐four patients with CIU were referred to us during the period from 2000 through June of 2005. Seven of those, aged 9–16, failed therapy with high dose antihistamines even with the addition of alternate morning prednisone. Neoral brand of cyclosporine, 3 mg/kg/day divided b.i.d., was initiated in these patients. Cyclosporine serum concentrations, blood urea nitrogen (BUN), creatinine, and blood pressure were routinely monitored. Results: All had cessation of hives. This occurred after 1–4 weeks for six of the seven and 8 weeks for one. While some experienced relapses, all were eventually off of all medications and free of hives. None of the seven experienced any adverse effects. Conclusions: Our experience in children is consistent with a previous controlled clinical trial in adults and supports the efficacy and safety of cyclosporine for CIU. However, we recommend that it be reserved for those whose CIU that is resistant to conventional measures and that patients be carefully monitored with cyclosporine serum concentrations and measures of renal function. 相似文献
999.
Anthony P. Belanger John F. Byrne Justin M. Paolino Timothy R. DeGrado 《Nuclear medicine and biology》2009,36(8):955-959
The bubble point test is the de facto standard for postproduction filter membrane integrity test in the radiopharmaceutical community. However, the bubble point test depends on a subjective visual assessment of bubbling rate that can be obscured by significant diffusive gas flows below the manufacturer's prescribed bubble point. To provide a more objective means to assess filter membrane integrity, this study evaluates the pressure-hold test as an alternative to the bubble point test. In our application of the pressure-hold test, the nonsterile side of the sterilizing filter is pressurized to 85% of the predetermined bubble point with nitrogen, the filter system is closed off from the pressurizing gas and the pressure is monitored over a prescribed time interval. The drop in pressure, which has a known relationship with diffusive gas flow, is used as a quantitative measure of membrane integrity. Characterization of the gas flow vs. pressure relationship of each filter/solution combination provides an objective and quantitative means for defining a critical value of pressure drop over which the membrane is indicated to be nonintegral. The method is applied to sterilizing filter integrity testing associated with the commonly produced radiopharmaceuticals, [18F]FDG and [11C]PIB. The method is shown to be robust, practical and amenable to automation in radiopharmaceutical manufacturing environments (e.g., hot cells). 相似文献
1000.