全文获取类型
收费全文 | 626篇 |
免费 | 31篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 33篇 |
妇产科学 | 7篇 |
基础医学 | 70篇 |
口腔科学 | 18篇 |
临床医学 | 83篇 |
内科学 | 117篇 |
皮肤病学 | 69篇 |
神经病学 | 13篇 |
特种医学 | 126篇 |
外科学 | 25篇 |
综合类 | 22篇 |
预防医学 | 23篇 |
眼科学 | 4篇 |
药学 | 15篇 |
1篇 | |
肿瘤学 | 33篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 14篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 29篇 |
2009年 | 29篇 |
2008年 | 15篇 |
2007年 | 23篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 37篇 |
1997年 | 46篇 |
1996年 | 40篇 |
1995年 | 21篇 |
1994年 | 30篇 |
1993年 | 22篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 25篇 |
1988年 | 21篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有662条查询结果,搜索用时 15 毫秒
581.
Cutaneous lymphoblastic lymphoma with pre-B markers 总被引:2,自引:0,他引:2
Two children with cutaneous convoluted lymphoblastic lymphoma are reported. Malignant cells from both patients contained cytoplasmic Mu heavy chains characteristic of pre-B-cells and expressed CALLA and la antigens as well. Most cases of convoluted lymphoblastic lymphoma are T- cell-derived neoplasms. The non-T, non-B phenotype found in these two children demonstrates that histology does not necessarily predict immunophenotype. The association of the pre-B phenotype with cutaneous lymphoma has not been previously reported, but may represent a unique clinical-histopathologic-immunologic entity that occurs in young children. 相似文献
582.
583.
Bladder cancer: staging with CT and MR imaging 总被引:10,自引:0,他引:10
Magnetic resonance (MR) imaging and computed tomography (CT) were compared in 30 patients with histologically proved bladder cancer. MR imaging was accurate in depicting the presence or absence of extravesical spread in 22 patients (accuracy, 73%; sensitivity, 82%; specificity, 62%), and CT was accurate in 24 patients (accuracy, 80%; sensitivity, 94%; specificity, 62%). The MR examinations of two patients were of undiagnostic quality and therefore considered to be technical failures. Each technique resulted in five false-positive and one false-negative examination for the diagnosis of extravesical tumor spread. In 28 patients the integrity of the bladder wall was assessed with MR imaging. In 22 patients the bladder wall was disrupted, and 18 of these patients had deep muscle invasion. In six patients the bladder wall was intact, and none of these patients had evidence of deep muscle invasion at pathologic examination. In this study MR imaging was slightly inferior to CT in the delineation of invasive tumors beyond the bladder wall. However, if one excludes from analysis the two patients with undiagnostic studies, there is no significant difference in accuracy between the two techniques. 相似文献
584.
Melissa Pulitzer Olakunle Ogunrinade Oscar Lin Peter Steinherz 《Journal of cutaneous pathology》2015,42(3):182-187
Anaplastic large cell lymphoma (ALCL) either as primary cutaneous or nodal disease is rare in children and difficult to distinguish, which is important both prognostically and for treatment purposes. We present a case of anaplastic lymphoma kinase (ALK)+ skin‐limited ALCL that highlights this challenge and draws attention to pitfalls in assessing ALK status. The patient was an 11‐year old girl with a twice recurrent nodule on her right shoulder. Each biopsy revealed a deep infiltrate of atypical lymphocytes that expressed CD3, CD4, CD43, CD45RO and CD30. The initial biopsy was epithelial membrane antigen (EMA)+ with vague cytoplasmic ALK‐1 positivity by immunohistochemistry, while the second biopsy was EMA+ and nuclear ALK‐1+. Fluorescence in situ hybridization analysis for an ALK (2p23) rearrangement of the first specimen was negative, while an ALK gene rearrangement was present in the second specimen. Therefore, this case was treated as nodal ALCL, despite negative bone marrow and radiographic imaging studies. The patient was treated with combination chemotherapy and remains disease‐free. Demonstration of nuclear ALK‐positivity, ALK (2p23) gene rearrangement is suggestive of systemic ALCL. Without evidence of systemic disease, this case highlights challenges of skin‐limited ALCL, whose clinical behavior as either cutaneous ALCL systemic ALCL may not be immediately apparent. 相似文献
585.
Aversa F; Tabilio A; Terenzi A; Velardi A; Falzetti F; Giannoni C; Iacucci R; Zei T; Martelli MP; Gambelunghe C 《Blood》1994,84(11):3948-3955
Patients who undergo transplantation with haploidentical "three-loci" mismatched T-cell-depleted bone marrow (BM) are at high risk for graft failure. To overcome the host-versus-graft barrier, we increased the size of the graft inoculum, which has been shown to be a major factor in controlling both immune rejection and stem cell competition in murine models. Seventeen patients (mean age, 23.2 years; range, 6 to 51 years) with end-stage chemoresistant leukemia were received transplants of a combination of BM with recombinant human granulocyte colony- stimulating factor-mobilized peripheral blood progenitor cells from HLA- haploidentical "three-loci" incompatible family members. The average concentration of colony-forming unit-granulocyte-macrophage in the final inoculum was sevenfold to 10-fold greater than that found in BM alone. The sole graft-versus-host disease (GVHD) prophylaxis consisted of T-cell depletion of the graft by the soybean agglutination and E- rosetting technique. The conditioning regimen included total body irradiation in a single fraction at a fast dose rate, antithymocyte globulin, cyclophosphamide and thiotepa to provide both immunosuppression and myeloablation. One patient rejected the graft and the other 16 had early and sustained full donor-type engraftment. One patient who received a much greater quantity of T lymphocytes than any other patient died from grade IV acute GVHD. There were no other cases of GVHD > or = grade II. Nine patients died from transplant-related toxicity, 2 relapsed, and 6 patients are alive and event-free at a median follow-up of 230 days (range, 100 to 485 days). Our results show that a highly immunosuppressive and myeloablative conditioning followed by transplantation of a large number of stem cells depleted of T lymphocytes by soybean agglutination and E-rosetting technique has made transplantation of three HLA-antigen disparate grafts possible, with only rare cases of GVHD. 相似文献
586.
Polymorphonuclear neutrophils (PMNs) were isolated from 24 healthy adults 20 to 61 years of age and the proportion of cells that demonstrated depolarization responses to the synthetic chemotaxin N- formyl-methionyl-leucyl-phenylalanine (FMLP) were enumerated using the lipophilic fluorescent cyanine dye 3,3'-di-pentyl-oxacarbocyanine [di-O- C(5)(3)] and flow cytometry. The membrane potential responses were correlated to the cells' respiratory burst capabilities as measured by nitroblue tetrazolium (NBT) reduction and/or superoxide production in response to FMLP; 40.2% +/- 15.1% (mean +/- SD) of cells depolarized to FMLP. The mean SE for duplicate determinations 1 hour apart was 3.8% (range 0.4% to 13.6%, n = 15). There was no correlation between the percentage of depolarizing PMNs and the yield of cells, the percentage of immature cells, or the circulating WBC count. There was no difference in the average age of men (34.9 +/- 9.9 years, n = 11) v women (33.8 +/- 8.5, n = 13) (mean +/- SD) studied, or in the percentage of depolarizing PMNs when men and women were compared (42.2 +/- 10.6% v 43.1 +/- 13.3%, respectively). However, there was a significant increase in the percentage of depolarizing PMNs with increasing age of women (r = .61, P less than .025) but not men (r = .03, P greater than .05). Analysis of variance revealed significantly greater person-to-person variability in the membrane potential response than in day-to-day variability in the same person (P less than .0005). The percentage of depolarizing PMNs in response to FMLP was significantly correlated with the percentage of NBT-positive cells from both purified PMNs and from whole blood (r = .849, P less than .0005, r = .857, P less than .05, respectively), and with the amount of superoxide produced, expressed as a percentage of that amount produced by cytochalasin B (cyto-B)-pretreated cells (r = .565, P less than .01). The data indicate that PMNs from healthy adults demonstrate a heterogeneous membrane potential response to the chemotaxin FMLP that correlates with the cells' oxidative responsiveness and that intersubject differences can be detected. In addition, the proportion of responsive PMNs increases with increasing age in women. 相似文献
587.
Background: Scleroderma/morphea is characterized by expansion of the dermis with thickened collagen bundles and loss of CD34+ dermal dendrocytes. Variable elastic fiber changes have been described, but to our knowledge, no systematic study of the elastic fiber pattern correlated with CD34 expression has been reported.
Methods: To better define the typical elastic fiber morphology, we examined seven cases of normal skin and 28 cases of scleroderma/morphea ranging from inflammatory to sclerosing stages. All but four biopsies were submitted with a clinical impression of either scleroderma or morphea. CD34 immunohistochemistry was performed on 26 biopsies with available tissue.
Results: Elastic van Gieson stain showed preservation of elastic fibers in all cases. In addition, straightening with parallel orientation and compression between thickened collagen bundles was frequently present and was graded as limited in 46% and diffuse in 54% of cases. The extent of elastic fiber alteration correlated with the degree of sclerosis. A variable loss of CD34+ dermal dendritic cells was seen in all cases.
Conclusion: This study confirms the preservation and frequent presence of parallel, straightened and compressed elastic fibers in scleroderma/morphea and suggests that the elastic fiber pattern, in addition to CD34 immunohistochemistry, may serve as a useful diagnostic adjunct. 相似文献
Methods: To better define the typical elastic fiber morphology, we examined seven cases of normal skin and 28 cases of scleroderma/morphea ranging from inflammatory to sclerosing stages. All but four biopsies were submitted with a clinical impression of either scleroderma or morphea. CD34 immunohistochemistry was performed on 26 biopsies with available tissue.
Results: Elastic van Gieson stain showed preservation of elastic fibers in all cases. In addition, straightening with parallel orientation and compression between thickened collagen bundles was frequently present and was graded as limited in 46% and diffuse in 54% of cases. The extent of elastic fiber alteration correlated with the degree of sclerosis. A variable loss of CD34
Conclusion: This study confirms the preservation and frequent presence of parallel, straightened and compressed elastic fibers in scleroderma/morphea and suggests that the elastic fiber pattern, in addition to CD34 immunohistochemistry, may serve as a useful diagnostic adjunct. 相似文献
588.
589.
590.
Much of what is known about activity-dependent plasticity comes from studies of the primary visual cortex and its inputs in higher mammals, but the molecular bases remain largely unknown. Similar functional plasticity takes place during a critical period in the visual cortex of the mouse, an animal in which genetic experiments can readily be performed to investigate the underlying molecular and cellular events. The experiments of this paper were directed toward understanding whether anatomical changes accompany functional plasticity in the developing visual cortex of the mouse, as they do in higher mammals. In normal mice, transneuronal label after an eye injection clearly delineated the monocular and binocular zones of area 17. Intrinsic signal optical imaging also showed monocular and binocular zones of area 17 but revealed no finer organization of ocular dominance or orientation selectivity. In normal animals, single geniculocortical afferents serving the contralateral eye showed great heterogeneity and no clustering consistent with the presence of ocular dominance patches. Growth and elaboration of terminal arbor continues beyond postnatal day 40 (P40), after the peak of the critical period. After prolonged monocular deprivation (MD) from P20 to P60, transneuronal labeling showed that the projection serving the ipsilateral eye was severely affected, whereas the effect on the contralateral eye's pathway was inconsistent. Optical imaging also showed profound effects of deprivation, particularly in the ipsilateral pathway, and microelectrode studies confirmed continued functional plasticity past P40. Reconstruction of single afferents showed that MD from P20 to P40 promoted the growth of the open eye's geniculocortical connections without causing the closed eye's contralateral projection to shrink, whereas MD from P20 to P60 caused an arrest of growth of deprived arbors. Our findings reveal numerous similarities between mouse and higher mammals in development and plasticity, along with some differences. We discuss the factors that may be responsible for these differences. 相似文献