全文获取类型
收费全文 | 7337篇 |
免费 | 541篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 232篇 |
妇产科学 | 143篇 |
基础医学 | 867篇 |
口腔科学 | 204篇 |
临床医学 | 838篇 |
内科学 | 1559篇 |
皮肤病学 | 95篇 |
神经病学 | 363篇 |
特种医学 | 318篇 |
外科学 | 1018篇 |
综合类 | 234篇 |
预防医学 | 472篇 |
眼科学 | 101篇 |
药学 | 594篇 |
中国医学 | 16篇 |
肿瘤学 | 789篇 |
出版年
2023年 | 32篇 |
2022年 | 51篇 |
2021年 | 153篇 |
2020年 | 85篇 |
2019年 | 124篇 |
2018年 | 159篇 |
2017年 | 103篇 |
2016年 | 132篇 |
2015年 | 141篇 |
2014年 | 205篇 |
2013年 | 305篇 |
2012年 | 426篇 |
2011年 | 423篇 |
2010年 | 259篇 |
2009年 | 230篇 |
2008年 | 375篇 |
2007年 | 440篇 |
2006年 | 426篇 |
2005年 | 367篇 |
2004年 | 345篇 |
2003年 | 334篇 |
2002年 | 301篇 |
2001年 | 275篇 |
2000年 | 247篇 |
1999年 | 201篇 |
1998年 | 124篇 |
1997年 | 92篇 |
1996年 | 106篇 |
1995年 | 71篇 |
1994年 | 64篇 |
1993年 | 66篇 |
1992年 | 126篇 |
1991年 | 93篇 |
1990年 | 110篇 |
1989年 | 105篇 |
1988年 | 110篇 |
1987年 | 84篇 |
1986年 | 72篇 |
1985年 | 78篇 |
1984年 | 50篇 |
1983年 | 53篇 |
1982年 | 28篇 |
1981年 | 31篇 |
1980年 | 24篇 |
1979年 | 38篇 |
1978年 | 28篇 |
1977年 | 24篇 |
1976年 | 20篇 |
1975年 | 24篇 |
1974年 | 28篇 |
排序方式: 共有7918条查询结果,搜索用时 15 毫秒
61.
Prevention of immune dysfunction and vitamin E loss by dehydroepiandrosterone and melatonin supplementation during murine retrovirus infection
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhang Z Araghi-Niknam M Liang B Inserra P Ardestani SK Jiang S Chow S Watson RR 《Immunology》1999,96(2):291-297
Female C57BL/6 mice infected with the LP-BM5 leukaemia retrovirus developed murine acquired immune-deficiency syndrome (AIDS). Dehydroepiandrosterone (DHEA) and melatonin (MLT) modify immune dysfunction and prevent lipid peroxidation. We investigated whether DHEA and MLT could prevent immune dysfunction, excessive lipid peroxidation, and tissue vitamin E loss induced by retrovirus infection. Retrovirus infection inhibited the release of T helper 1 (Th1) cytokines, stimulated secretion of Th2 cytokines, increased hepatic lipid peroxidation, and induced vitamin E deficiency. Treatment with DHEA or MLT alone, as well as together, largely prevented the reduction of B- and T-cell proliferation as well as of Th1 cytokine secretion caused by retrovirus infection. Supplementation also suppressed the elevated production of Th2 cytokines stimulated by retrovirus infection. DHEA and MLT simultaneously reduced hepatic lipid peroxidation and prevented vitamin E loss. The use of DHEA plus MLT was more effective in preventing retrovirus-induced immune dysfunction than either DHEA or MLT alone. These results suggest that supplementation with DHEA and MLT may prevent cytokine dysregulation, lipid oxidation and tissue vitamin E loss induced by retrovirus infection. Similarly, hormone supplementation also modified immune function and increased tissue vitamin E levels in uninfected mice. 相似文献
62.
Xiao Y Zhang Wing Y Chan Bruce M Whitney Dai M Fan John H S Chow Yong Liu Enders K W Ng Sheung C S Chung 《Diagnostic molecular pathology》2002,11(3):135-139
Helicobacter pylori (HP) infection induces expression of IL-8 and IL-10 in benign gastric epithelium. This study compared the expression of cytokines in CD4+ and CD8+ lymphocyte subsets of peripheral blood lymphocytes (PBL), benign mucosal lymphocytes (ML), and tumor infiltrative lymphocytes (TIL) as well as in the benign and malignant epithelial cells of the same patient, with respect to the presence of HP infection, lymph node metastases, and tumor histologic type. The mRNA of the cytokines was measured by a semiquantitative RT-PCR method. The levels were ranked and compared using the Wilcoxon sign-ranked test. Compared with CD8+ ML, the CD8+ TIL expresses higher levels of IL-6 and IL-8 but lower level of IL-4 in patients with lymph node metastases. In patients with HP infection, expression of IL-8 and IL-10 was higher in the gastric carcinoma cells than in the benign epithelial cells while expression of IL-6 and IL-8 were higher in CD8+ TIL than CD8+ ML. Overexpression of IL-8 in HP associated gastric carcinomas suggested that they might have arisen from HP-infected epithelial cells. 相似文献
63.
64.
The CTLA-4 gene region of chromosome 2q33 is linked to, and associated with, type 1 diabetes. Belgian Diabetes Registry 总被引:8,自引:1,他引:8
Nistico L; Buzzetti R; Pritchard LE; Van der Auwera B; Giovannini C; Bosi E; Larrad MT; Rios MS; Chow CC; Cockram CS; Jacobs K; Mijovic C; Bain SC; Barnett AH; Vandewalle CL; Schuit F; Gorus FK; Tosi R; Pozzilli P; Todd JA 《Human molecular genetics》1996,5(7):1075-1080
Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus
is determined by a combination of environmental and genetic factors, which
include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin
gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2
cannot explain the clustering of type 1 diabetes in families, and a role
for other genes is inferred. In the present report we describe linkage and
association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte
associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong
candidate gene for T cell- mediated autoimmune disease because it encodes a
T cell receptor that mediates T cell apoptosis and is a vital negative
regulator of T cell activation. In addition, we provide supporting evidence
that CTLA-4 is associated with susceptibility to Graves' disease, another
organ- specific autoimmune disease.
相似文献
65.
A case of clear cell chondrosarcoma in a Chinese patient is described. The clear cells showed strongly positive S-100 protein immunoreactivity. Ultrastructurally 2 types of chondroid cells were demonstrated. One type appeared more primitive with abundant electron-lucent cytoplasm and sparse organelles. The other type of cell was more differentiated with presence of microvilli and numerous dilated cisternae of endoplasmic reticulum. Previous ultrastructural studies on these lesions were reviewed and compared with the present findings. 相似文献
66.
67.
Allelic loss of chromosome 6q in gastric carcinoma. 总被引:1,自引:0,他引:1
Brenda C Y Li Wing Y Chan Christine Y S Li Chit Chow Enders K W Ng S C Sydney Chung 《Diagnostic molecular pathology》2003,12(4):193-200
Loss of the long arm of chromosome 6 (6q) has frequently been reported in gastric carcinoma, and most gastric cancer patients have evidence of intestinal metaplasia in the stomach. However, the relationship between loss of chromosome 6q and intestinal metaplasia has not been studied. In the first part of the study, we define the critical deletion region of chromosome 6q using loss of heterozygosity technique (LOH). Seventeen microsatellite markers were used to detect loss of heterozygosity (LOH) in 37 microdissected gastric tumors. We also examined intestinal metaplasia (IM) foci of the stomach in the same cancer patient (17 cases). Losses on chromosome 6q were detected in high frequency (51%) by LOH. Two distinct regions of common allelic loss were identified: one centered on the marker D6S300 (at 6q16.1) and the second on D6S446 (at 6q27), with LOH frequency of 36% and 31.3%, respectively. The deletions fall into 2 discrete regions, suggesting the existence of at least 2 tumor suppressor genes in 6q. The losses at 6q27 were confirmed by fluorescence in situ hybridization study (FISH). In the cases with LOH in the tumor, no LOH were detected in the autologous IM areas, but losses were detected by FISH. In some cases, these genetic changes may be acquired in the transition from normal gastric mucosa to intestinal metaplasia. 相似文献
68.
A number of systemic abnormalities associated with cholestasis have been reported in the literature. This paper describes two unrelated patients with cholestasis and an unusual constellation of abnormalities including cleft palate/lip, hydronephrosis/hydroureter, retinal pigmentation, and intestinal septum. 相似文献
69.
A thermally responsive amphiphilic grafted copolymer comprised of hydroxyl-containing random poly(N-isopropylacrylamide-co-N-hydroxylmethylacrylamide) as the hydrophilic chain and cholesteryl groups as hydrophobic side arms was developed for the controlled release of hydrophobic drugs. The polymer was temperature-sensitive with a lower critical solution temperature of 40.5 degrees C and a critical micelle concentration of 4 mg/l. Dynamic light-scattering studies showed that the amphiphilic polymer self-assembled into micelles in aqueous media with their mean sizes in the range of 25-34 nm. Transmission electron microscope studies showed that the nanoparticles prepared from the micelle solutions exhibited multiple morphologies including unusual cubic and cuboids-like shapes, and normal spherical shapes, which could be controlled by the formation conditions. Wide-angle X-ray scattering studies showed that these nanoparticles were amorphous in nature but a small crystalline phase existed and the crystallinity of particles increased with the decrease of initial formation concentration. Pyrene was employed as a model hydrophobic agent to examine the encapsulation ability of the polymer with respect to hydrophobic agents in aqueous media. The loading level of the polymer with respect to pyrene was 4.4 mg/g, indicating that the thermally responsive amphiphilic polymer would be able to be used for the encapsulation of hydrophobic drugs. 相似文献
70.
L.E. Scutt E.W.C. Chow R. Weksberg W.G. Honer Anne S. Bassett 《American journal of medical genetics. Part A》2001,105(8):713-723
Congenital dysmorphic features are prevalent in schizophrenia and may reflect underlying neurodevelopmental abnormalities. A cluster analysis approach delineating patterns of dysmorphic features has been used in genetics to classify individuals into more etiologically homogeneous subgroups. In the present study, this approach was applied to schizophrenia, using a sample with a suspected genetic syndrome as a testable model. Subjects (n = 159) with schizophrenia or schizoaffective disorder were ascertained from chronic patient populations (random, n = 123) or referred with possible 22q11 deletion syndrome (referred, n = 36). All subjects were evaluated for presence or absence of 70 reliably assessed dysmorphic features, which were used in a three‐step cluster analysis. The analysis produced four major clusters with different patterns of dysmorphic features. Significant between–cluster differences were found for rates of 37 dysmorphic features (P < 0.05), median number of dysmorphic features (P = 0.0001), and validating features not used in the cluster analysis: mild mental retardation (P = 0.001) and congenital heart defects (P = 0.002). Two clusters (1 and 4) appeared to represent more developmental subgroups of schizophrenia with elevated rates of dysmorphic features and validating features. Cluster 1 (n = 27) comprised mostly referred subjects. Cluster 4 (n = 18) had a different pattern of dysmorphic features; one subject had a mosaic Turner syndrome variant. Two other clusters had lower rates and patterns of features consistent with those found in previous studies of schizophrenia. Delineating patterns of dysmorphic features may help identify subgroups that could represent neurodevelopmental forms of schizophrenia with more homogeneous origins. © 2001 Wiley‐Liss, Inc. 相似文献