全文获取类型
收费全文 | 21099篇 |
免费 | 1287篇 |
国内免费 | 118篇 |
专业分类
耳鼻咽喉 | 205篇 |
儿科学 | 441篇 |
妇产科学 | 308篇 |
基础医学 | 3039篇 |
口腔科学 | 310篇 |
临床医学 | 2120篇 |
内科学 | 5116篇 |
皮肤病学 | 471篇 |
神经病学 | 2178篇 |
特种医学 | 1280篇 |
外国民族医学 | 1篇 |
外科学 | 3383篇 |
综合类 | 111篇 |
一般理论 | 10篇 |
预防医学 | 857篇 |
眼科学 | 379篇 |
药学 | 1144篇 |
中国医学 | 16篇 |
肿瘤学 | 1135篇 |
出版年
2023年 | 155篇 |
2022年 | 213篇 |
2021年 | 469篇 |
2020年 | 294篇 |
2019年 | 393篇 |
2018年 | 465篇 |
2017年 | 351篇 |
2016年 | 491篇 |
2015年 | 530篇 |
2014年 | 713篇 |
2013年 | 949篇 |
2012年 | 1491篇 |
2011年 | 1498篇 |
2010年 | 892篇 |
2009年 | 868篇 |
2008年 | 1355篇 |
2007年 | 1369篇 |
2006年 | 1296篇 |
2005年 | 1292篇 |
2004年 | 1127篇 |
2003年 | 1035篇 |
2002年 | 938篇 |
2001年 | 335篇 |
2000年 | 329篇 |
1999年 | 341篇 |
1998年 | 231篇 |
1997年 | 208篇 |
1996年 | 136篇 |
1995年 | 134篇 |
1994年 | 107篇 |
1993年 | 96篇 |
1992年 | 158篇 |
1991年 | 149篇 |
1990年 | 155篇 |
1989年 | 160篇 |
1988年 | 94篇 |
1987年 | 99篇 |
1986年 | 102篇 |
1985年 | 81篇 |
1984年 | 78篇 |
1983年 | 63篇 |
1982年 | 60篇 |
1979年 | 93篇 |
1978年 | 54篇 |
1977年 | 53篇 |
1975年 | 49篇 |
1974年 | 72篇 |
1973年 | 55篇 |
1972年 | 61篇 |
1971年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Jürgen Bohl Hans Steinmetz Stephan Störkel 《Virchows Archiv : an international journal of pathology》1991,419(1):51-58
Summary Intracellular fibrillar congophilic inclusions are well known as neurofibrillary tangles in neurons and as Biondi bodies in choroid plexus epithelial cells. Recently similar amyloid-like inclusions in adrenal cortical cells were described (Eriksson and Westermark 1990). This study on 150 adrenal glands confirms these observations. In our material the age-related accumulation of congophilic inclusions starts earlier (in the sixth decade) and reaches a higher incidence (42.7%). We found similar intracellular inclusions in other endocrine organs, for example in the anterior lobe of the pituitary, in the cells of parathyroid glands and in Sertoli cells. The age-related incidence of these fibrillar inclusions in the pituitary was 68%; the co-incidence with interstitial amyloid deposits was 49.5%. Thus the intracellular accumulation of congophilic fibrils in old age is a widespread phenomenon and occurs not only in neurons but also in endocrine cells (adrenal, pituitary and parathyroid glands) and in active secretory cells (choroid plexus and Sertoli cells). 相似文献
92.
Modulation of Whole-Cell Currents in Plasmodium Falciparum-Infected Human Red Blood Cells by Holding Potential and Serum 总被引:3,自引:0,他引:3
Henry M. Staines Trevor Powell J. Clive Ellory Stéphane Egée Franck Lapaix Gaëtan Decherf Serge L. Y. Thomas Christophe Duranton† Florian Lang† Stephan M. Huber† 《The Journal of physiology》2003,552(1):177-183
Recent electrophysiological studies have identified novel ion channel activity in the host plasma membrane of Plasmodium falciparum -infected human red blood cells (RBCs). However, conflicting data have been published with regard to the characteristics of induced channel activity measured in the whole-cell configuration of the patch-clamp technique. In an effort to establish the reasons for these discrepancies, we demonstrate here two factors that have been found to modulate whole-cell recordings in malaria-infected RBCs. Firstly, negative holding potentials reduced inward currents (i.e. at negative potentials), although this result was highly complex. Secondly, the addition of human serum increased outward currents (i.e. at positive potentials) by approximately 4-fold and inward currents by approximately 2-fold. These two effects may help to resolve the conflicting data in the literature, although further investigation is required to understand the underlying mechanisms and their physiological relevance in detail. 相似文献
93.
A comparative study of the expression of cytotoxic proteins in allergic contact dermatitis and psoriasis: spongiotic skin lesions in allergic contact dermatitis are highly infiltrated by T cells expressing perforin and granzyme B 总被引:1,自引:0,他引:1 下载免费PDF全文
Yawalkar N Hunger RE Buri C Schmid S Egli F Brand CU Mueller C Pichler WJ Braathen LR 《The American journal of pathology》2001,159(3):803-808
Recent reports indicate that cytotoxic T cells are critically involved in contact hypersensitivity reactions in animals. In this study we sought to investigate the in vivo expression of cytotoxic granule proteins in the elicitation phase of allergic contact dermatitis in humans. Skin biopsy specimens were obtained from patients with allergic contact dermatitis (n = 8) and psoriasis (n = 6) and from controls with normal skin (n = 6). Expression of perforin and granzyme B was investigated by in situ hybridization and immunohistochemistry. In contrast to normal skin and psoriasis, a significant enhancement of perforin and granzyme B gene expression and immunoreactivity was observed in the mononuclear cell infiltrate of allergic contact dermatitis. Immunoreactivity for perforin and granzyme B was mainly found in the cytoplasm of lymphocytic cells, which were located in the dense perivascular infiltrate as well as at sites of marked spongiosis in the epidermis. Double immunostaining revealed that both CD4+ and CD8+ T cells are capable of expressing perforin and granzyme B. In conclusion, our data suggest that T-cell-mediated mechanisms involving cytotoxic granule proteins may elicit epidermal cell injury in vivo and thereby strongly contribute to the development of allergic contact dermatitis in humans. 相似文献
94.
We report two families selected from 124 genotyped Caucasian insulin-dependent diabetes mellitus (IDDM) families because of unusual features. In both families, all offspring are affected and four out of six bear the allele HLA-DR2 which is an uncommon phenotype among diabetic patients. Onset before the age of 1 year in all the patients of one family, association with optic atrophy in the other, and the existence of pairs of affected sibs of different HLA types in both, are infrequent findings and support the evidence of heterogeneity in IDDM. 相似文献
95.
We investigated a possible cause-and-effect relationship between sensitization against Actinomyces viscosus Nyl and destructive periodontal disease in RIC-Sprague-Dawley rats. Germfree rats (66) were either immunized with A. viscosus Nyl (day 20) or orally infected with A. viscosus Nyl (days 38 and 39) or both. We measured alveolar bone loss in maxillary and mandibular molars, in vitro T-lymphocyte responsiveness, and serum antibody titers. In immunized and monoassociated rats bone loss in both jaws progressed rapidly between days 37 and 72, whereas the rate of further resorption decreased until day 100. In monoassociated rats, development of bone loss was much slower, and the maximum resorption measured was, at best, half of the bone loss compared with the former group. However, no amplification of bone loss by immunization was observed in a second experiment using 63 conventional rats kept in relative gnotobiosis. Antibody titers to A. viscosus Nyl in gnotobiotic monoassociated rats were higher in immunized animals, whereas no difference was found in the respective groups of the relative gnotobiotic experiment. The fact that immunization more than doubled alveolar bone loss in gnotobiotic monoassociated rats confirms the allergic nature of the disease. The lack of such an effect under conventional conditions points to suppressor mechanisms whose decrease might convert stable periodontal lesions into progressive ones. 相似文献
96.
Lena Möbus Elke Rodriguez Inken Harder Agatha Schwarz Ulrike Wehkamp Dora Stölzl Nicole Boraczynski Sascha Gerdes Thomas Litman Andreas Kleinheinz Susanne Abraham Annice Heratizadeh Christiane Handrick Eva Haufe Jochen Schmitt Thomas Werfel Stephan Weidinger 《The Journal of allergy and clinical immunology》2021,147(5):1959-1965.e2
97.
van den Engel NK an Haack M Martin S Kolb H 《Journal of molecular medicine (Berlin, Germany)》2002,80(5):301-308
Adhesion molecules are important for leukocyte extravasation and for the delivery of costimulatory signals in T cell activation. We therefore interfered in the immune process leading to islet inflammation in diabetes prone NOD mice by oral vaccination with plasmid DNA encoding soluble ICAM-1. Female NOD mice were treated orally with ICAM-1, TGF-beta, or control plasmid DNA and received a single injection of cyclophosphamide for synchronization and acceleration of the disease process in the pancreas. Quantitative RT-PCR analysis of pancreatic mRNA showed that cyclophosphamide induced the expression of Th1 cytokines (IFN-gamma and IL-12p40) in vehicle- or control plasmid-treated mice. Treatment with ICAM-1 and TGF-beta DNA resulted in increased levels of IL-10 mRNA in the pancreas, indicating an anti-inflammatory regulatory immune response. Histological analysis of pancreatic islets showed that the DNA treatment did not alter islet infiltration in response to cyclophosphamide. Hence vaccination with the ICAM-1 plasmid had not suppressed leukocyte migration but rather modulated lymphocyte activity, similarly as seen for the TGF-beta-encoding plasmid. Neither of the three plasmids caused recognizable changes in cytokine expression in the small intestine, Peyer's patches, or mesenteric lymph nodes. We conclude that oral vaccination with DNA encoding immunoregulatory molecules such as ICAM-1 and TGF-beta represents an approach for modulating the ongoing inflammatory process in the pancreas of diabetes prone NOD mice. 相似文献
98.
P. Spieler D. Kradolfer U. Schmid 《Virchows Archiv : an international journal of pathology》1986,409(2):211-221
Summary The cytological diagnosis of malignant Lymphoma in serous effusions can be difficult because reactive lymphocytes may be morphologically indistinguishable from malignant cells in lymphocytic and other low grade Non-Hodgkin's lymphomas. As a result of the present study, diagnostic accuracy can be improved by means of B- and T-cell enumeration using an immunoalkaline-phosphatase method (IAP). 30 cytological specimens, including 28 pleural, 1 pericardial and 1 ascitic fluids, were studied with a panel of monoclonal anti B- and anti T-cell antibodies (PAN B, kappa, lambda, T1, T2, OKT4, T8). Reactive lymphocytic effusions were characterized by a predominance of T cells constituting 80% of all lymphocytes with an excess of helper/inducer cells (mean helper to suppressor ratio 3.0) and by a surface kappa to surface lambda ratio of 1.6 on B-cells. Tuberculous effusions showed a similar distribution of lymphocyte-subpopulations whilst most of the carcinomatous fluids showed a lower percentage of T cells (lowest value 67%) and lower Th:Ts ratio (mean 2.0). Lymphoid cells in samples of five B-cell lymphomas were characterized by T-cell depression ( 70%). B-cells in three cases expressed clear cut light chain monoclonality which was at least suggested in the other two cases.Lymphoid cells from two cases of Hodgkin's disease expressed an indistinct immunological pattern. Labelling of cytoplasmic immunoglobulins (heavy and light chains) using the peroxidase antiperoxidase method (PAP) may be important to characterize neoplasms of the plasma cell series.It is concluded that the chosen panel of antibodies in combination with IAP labelling method may be of great value in identifying B-cell lymphomas. The technique can be used in the routine laboratory and storage of unlabelled and labelled slides over long periods is possible.Dedicated to Professor K. Lennert, Kiel, on the occasion of his 65th birthdayThis study was supported by the Krebsliga St. Gallen/Appenzell 相似文献
99.
Jan Schmeller Michael Wessolly Elena Mairinger Sabrina Borchert Thomas Hager Thomas Mairinger Kurt Werner Schmid Jeremias Wohlschlaeger Robert F.H. Walter Fabian D. Mairinger 《Pathology, research and practice》2019,215(2):381-386
Introduction
The usage of formalin-fixed paraffin embedded (FFPE) tissue is characterized by its long shelf-life and simple handling. Therefore it is the most commonly available tissue specimen in routine diagnostics and histological studies. Formaldehyde fixation may result in RNA degradation and cross linking with proteins, while storage conditions also affect RNA integrity. The present study was designed to investigate the influence of these factors on RNA analysis.Design
FFPE-derived RNA from sections of 23 patients with spontaneous pneumothoraxes was used. Unstained sections of FFPE tissue were stored at various temperatures (?80?°C, ?20?°C, 4?°C, 24?°C) prior to RNA extraction. The potential impact on RNA quality of semi-automatic and manual RNA isolation and three different deparaffinization agents (mineral oil, xylene and d-limonene) were compared.Results
The storage temperature of FFPE sections affects RNA concentration and fragmentation, with the optimal storage temperature below -20?°C. The RNA extracted with d-limonene shows equivalent quality to the RNA extracted using more toxic standard agents. The manual isolation provides a higher RNA yield compared to the semi-automatic isolation. However, no differences in the amount of longer RNA fragments were observed. Furthermore, the semi-automatic isolation showed an enhanced RNA quality.Conclusion
FFPE sections not directly used for RNA extraction should be stored below -20?°C to increase quality and yield of the RNA. Usage of semi-automatic isolation produces superior results and simplifies routine processes by having less hands-on-time. Replacement of toxic xylene by d-limonene may contribute to improved occupational safety while not influencing analytical results. 相似文献100.
A microassay for assessing two functions of polymorphonuclear leukocytes in the presence or absence of complement is presented. Requiring only minute amounts of blood (0.1 ml) and a minimum of laboratory equipment (microscope, incubator, and centrifuge), it allows the quantitation of phagocytosis and intracellular killing of microorganisms by leukocytes. To demonstrate the value of this assay, the phagocytic and microbicidal activity of leukocytes from healthy subjects and patients against Candida albicans was investigated. Apart from individual cases, no differences in the phagocytic activity between groups of healthy subjects and patients with candida vaginitis or different types of cancer could be found. However, the killing capacity of the leukocytes from women with recurrent candida vaginitis was reduced. The leukocytes of one patient showing a very low killing capacity lacked myeloperoxidase. Also, low values of killing were seen with leukocytes from three patients suffering from osteosarcoma, chronic lymphatic leukemia, or Hodgkins disease. 相似文献