全文获取类型
收费全文 | 15937篇 |
免费 | 1006篇 |
国内免费 | 260篇 |
专业分类
耳鼻咽喉 | 395篇 |
儿科学 | 212篇 |
妇产科学 | 326篇 |
基础医学 | 2625篇 |
口腔科学 | 237篇 |
临床医学 | 1191篇 |
内科学 | 3477篇 |
皮肤病学 | 406篇 |
神经病学 | 1030篇 |
特种医学 | 1318篇 |
外科学 | 2186篇 |
综合类 | 38篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 451篇 |
眼科学 | 519篇 |
药学 | 1251篇 |
中国医学 | 193篇 |
肿瘤学 | 1345篇 |
出版年
2024年 | 9篇 |
2023年 | 109篇 |
2022年 | 419篇 |
2021年 | 660篇 |
2020年 | 306篇 |
2019年 | 447篇 |
2018年 | 532篇 |
2017年 | 401篇 |
2016年 | 641篇 |
2015年 | 830篇 |
2014年 | 989篇 |
2013年 | 1142篇 |
2012年 | 1612篇 |
2011年 | 1451篇 |
2010年 | 979篇 |
2009年 | 817篇 |
2008年 | 1070篇 |
2007年 | 961篇 |
2006年 | 818篇 |
2005年 | 722篇 |
2004年 | 585篇 |
2003年 | 482篇 |
2002年 | 451篇 |
2001年 | 145篇 |
2000年 | 126篇 |
1999年 | 79篇 |
1998年 | 53篇 |
1997年 | 48篇 |
1996年 | 32篇 |
1995年 | 21篇 |
1994年 | 27篇 |
1993年 | 24篇 |
1992年 | 29篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 23篇 |
1988年 | 15篇 |
1987年 | 20篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1968年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
51.
Yuji Ohtsuki Bruce Mackay Jae Y. Ro Alberto G. Ayala 《Medical Electron Microscopy》1998,31(4):222-225
We report ribosome-lamella complexes (RLC) in cancer cells of transitional cell carcinoma (TCC) of the prostate in a 52-year-old Caucasian man. Histopathologically, cancer cells were proliferated in various-sized nests, mostly associated with central necrosis. Some invaded into the surrounding normal glandular space and the stroma, with occasional lymphatic invasion. Fine structural study of cancer cells revealed that cross-sectioned RLC as well as densely aggregated ribosomes were detected in their cytoplasm, situated close to, but not directly connected with, dilated rough endoplasmic reticulum. These were composed of a concentric alternative arrangement of both lamellae and ribosomes. In the central and surrounding parts of the RLC, ribosomes were observed, revealing a smooth transition to the ribosomal component of RLC in size and shape. The presence of both RLC and dense aggregation of ribosomes close to the rough endoplasmic reticulum suggests that their functions might be related to specific or aberrant protein synthesis under unknown conditions. Although RLC have been often reported in hematopoietic malignancies, their occurrence in the malignant epithelial component has been only reported in a case of pulmonary adenocarcinoma. This is the first report of RLC in TCC in the literature. 相似文献
52.
Min K Hong SM Kim KR Ro JY Park MJ Kim JS Kim JM Jung HC Yu E 《Pathology, research and practice》2003,199(1):1-8
Intramucosal Helicobacter pylori (H. pylori) has been described in biopsy tissues and culture systems. However, the association of intramucosal H. pylori with histopathologic features has not been evaluated. The purpose of this study is to investigate the relationship between intramucosal H. pylori and inflammatory reactions in H. pylori infection. In 113 randomly selected human gastric biopsies and 20 murine stomachs, which were inoculated with SSI every day for a week, immunohistochemical analysis for intramucosal H. pylori was done and correlated with histologic parameters. Electron microscopic examination was done on murine stomachs. H. pylori infection was present in 104 gastric biopsies and 17 murine stomachs. Intraepithelial immunopositivity for H. pylori was detected in 27 of 104 (26%) biopsies and in 11 of 17 (65%) murine stomachs. Lamina proprial immunopositivity for H. pylori was present in 51 of 104 (48%) biopsies. Neutrophil-associated immunopositivity for H. pylori was observed in 22 of 90 (24%) biopsies with H. pylori chronic active gastritis. Lamina proprial and neutrophil-associated immunopositivity for H. pylori correlated significantly with the density of H. pylori and the grade of acute inflammatory reaction in H. pylori gastritis. Intramucosal location of H. pylori itself or its antigen is closely associated with acute inflammatory reactions and may play an important role in establishing a persistent infection in chronic H. pylori gastritis. Furthermore, lamina proprial and/or neutrophil-associated H. pylori appears to be more important than intraepithelial H. pylori in acute inflammatory reactions of H. pylori gastritis. 相似文献
53.
Kang YS Yamazaki S Iyoda T Pack M Bruening SA Kim JY Takahara K Inaba K Steinman RM Park CG 《International immunology》2003,15(2):177-186
The marginal zone macrophages of the spleen are implicated in the clearance of polysaccharides, but underlying mechanisms need to be pinpointed. SIGN-R1 is one of five recently identified mouse genes that are homologous to human DC-SIGN and encode a single, external, C-terminal C-type lectin domain. We find that a polyclonal antibody to a specific SIGN-R1 peptide reacts primarily and strongly with a subset of macrophages in the marginal zone of spleen and lymph node medulla. In both sites, SIGN-R1 exists primarily in an aggregated form, resistant to dissociation into monomers upon boiling in SDS under reducing conditions. Upon transfection into three different cell lines, high-mol.-wt forms bearing SIGN-R1 are expressed, as well as reactivity with ER-TR9, a mAb previously described to react selectively with marginal zone macrophages. SIGN-R1-expressing macrophages preferentially sequester dextrans following i.v. injection. Likewise, when phagocytic cells are enriched from spleen and tested in culture, dextran is selectively endocytosed by a subset of very large SIGN-R1(+) cells representing approximately 5% of total released macrophages. Uptake of FITC-dextran by these macrophages in vivo and in vitro is blocked by ER-TR9 and polyclonal anti-SIGN-R1 antibodies. Following transfection with SIGN-R1, cell lines become competent to endocytose dextrans. The dextran localizes primarily to compartments lacking transferrin receptor and the LAMP-1 CD107a panlysosomal antigen. Therefore, SIGN-R1 mediates the uptake of dextran polysaccharides, and it is predominantly expressed in the macrophages of the splenic marginal zone and lymph node medulla. 相似文献
54.
Microsatellite alterations in hepatocellular carcinoma and intrahepatic cholangiocarcinoma 总被引:1,自引:0,他引:1
A series of 20 hepatocellular carcinomas and 8 intrahepatic cholangiocarcinomas was screened from the Korean population for microsatellite alterations, including a loss of heterozygosity and replication errors using nine microsatellite markers containing several genes. The microsatellite results and our previous comparative genomic hybridization results of two tumors were compared at each locus, and the correlations between these and clinicopathologic variables were examined. The most characteristic findings were found at 13q. Replication errors were prevalent at D13S160 (13q21.2 approximately q31) and D13S292(13q12). The incidence of loss of heterozygosity, however, was higher at D13S153 (13q14.1 approximately q14.3) and D13S265(13q31 approximately q32). In contrast, there were higher deletion frequencies observed in hepatocellular carcinoma (HCC) and higher amplification frequencies observed in intrahepatic cholangiocarcinoma at 13q in our previous comparative genomic hybridization (CGH) study. Higher frequencies of replication errors were observed at D16S408 (13q12 approximately q21) and D16S504(13q23 approximately q24) in the HCC. This study found that significant differences in the patterns of genetic instability of microsatellites were dependent on the chromosomal loci. It is believed that certain genes at altered CGH regions, which are relevant to the development and/or progression of these cancers, are activated by different mutation mechanisms. 相似文献
55.
Systemic Administration of Immunostimulatory DNA Sequences Mediates Reversible Inhibition of Th2 Responses in a Mouse Model of Asthma 总被引:10,自引:0,他引:10
Broide DH Stachnick G Castaneda D Nayar J Miller M Cho JY Roman M Zubeldia J Hayashi T Raz E Hyashi T 《Journal of clinical immunology》2001,21(3):175-182
This study investigated whether immunostimulatory DNA sequences (ISS) induce a transient or sustained inhibition of Th2 responses to inhaled antigen. We sensitized mice with subcutaneous injections to develop a Th2 response to ovalbumin (ova) and then administered a dose of ISS prior to ova inhalation challenge. Mice were then rechallenged with ova by inhalation a second time at varying time points after the first ova inhalation (1 to 8 weeks later) to determine whether the ISS dose administered prior to the first ova inhalation protected against a subsequent second ova inhalation challenge. A single dose of ISS inhibited the Th2 response to the first inhalation of ova antigen, as well as 4 weeks later to the second inhalation of ova. However, ISS did not inhibit a Th2 response to the second inhalation of ova 8 weeks later. The reversible inhibition of Th2 responses at 8 weeks suggests the need for repeated ISS administration at monthly intervals. 相似文献
56.
Diffuse optical tomography of breast cancer during neoadjuvant chemotherapy: a case study with comparison to MRI 总被引:1,自引:0,他引:1
Choe R Corlu A Lee K Durduran T Konecky SD Grosicka-Koptyra M Arridge SR Czerniecki BJ Fraker DL DeMichele A Chance B Rosen MA Yodh AG 《Medical physics》2005,32(4):1128-1139
We employ diffuse optical tomography (DOT) to track treatment progress in a female subject presenting with locally advanced invasive carcinoma of the breast during neoadjuvant chemotherapy. Three-dimensional images of total hemoglobin concentration and scattering identified the tumor. Our measurements reveal tumor shrinkage during the course of chemotherapy, in reasonable agreement with magnetic resonance images of the same subject. A decrease in total hemoglobin concentration contrast between tumor and normal tissue was also observed over time. The results demonstrate the potential of DOT for measuring physiological parameters of breast lesions during chemotherapy. 相似文献
57.
58.
Hybrid cell lines producing monoclonal antibodies against human prostatic acid phosphatase (E. C. 3.1.3.2) were prepared by the fusion of mouse myeloma cells with the spleen cells of BALB/c mice and Lewis rats immunized with prostatic acid phosphatase (PAP). Approximately 14% of the hybrid cell microcultures which produced specific antibodies were cloned, and 6 eventually yielded stable cell lines. The monoclonal antibodies produced by these 6 hybridomas were characterized for their isotypes, isoelectric points, concentrations and affinities. The specificity of these monoclonal antibodies was further investigated by radioimmunoassay and immunohistochemical methods. All of the 6 monoclonal antibodies exhibited strict specificity for prostatic acid phosphatase. 相似文献
59.
Three cases of microcystic adenomas of the pancreas with special reference to multicentric origin are described. The gross features and light microscopic findings were consistent with those described as being microcystic adenomas, but in two cases the gross examination and gelatin-embedded giant slices revealed multiple, isolated development of tumors ranging from submacroscopic nodules to tumors 4.5 cm in diameter. The larger tumors often showed ragged margins with small satellite nodules around the masses. A central fibrolamellar stellate core with centrifugally radiating septation was found in most of the tumor masses, even in the smaller ones. Ultrastructural and immunohistochemical findings revealed a single row of glycogen-rich epithelial cells, but participation of myoepithelial cells was not confirmed. Instead, vimentin-positive cells (pericytes) within the interstitial space incorporated closely with the basal lamina of the cyst wall. This study suggests that a small percentage of microcystic adenomas of the pancreas develop in multiple tumors, and some appear as a single tumor by their confluence. 相似文献
60.
Kim D Hur DY Kim YS Lee K Lee Y Cho D Kang JS Kim YI Hahm E Yang Y Yoon S Kim S Lee WB Park HY Kim YB Hwang YI Chang KY Lee WJ 《Human immunology》2002,63(7):576-587
Burkitt lymphoma (BL) is a tumor with the characteristics of germinal center B cells. We previously reported that the CM1 (centrocyte/-blast marker 1) molecule is expressed only in germinal center B cells, specifically, in a subpopulation of centroblasts and centrocytes. In the present study, we investigated the apoptosis induced by anti-CM1 in the Ramos and Raji human BL cell lines. The Ramos is protected from apoptosis by the crosslinking of sIgM and the calcium ionophore by the ligation of CD40 with anti-CD40 monoclonal antibodies (mAb) or soluble CD40 ligand (sCD40L). In this investigation on the effect of CM1 on apoptosis in BL cell lines, we found that cellular signaling by CM1 induces apoptosis and decreases cell viability, in BL cell lines cultured for 24 hours with protein-G agarose beads conjugated anti-CM1 mAb. Stimulation by CD40 ligated with sCD40L protected Raji cells from CM1-induced apoptosis, but did not protect Ramos cells. Furthermore, after anti-CM1 mAb stimulation, CD95 expression was upregulated and CD40 expression was unaltered or slightly decreased in Ramos cells, whereas CD95 was downregulated and CD40 was slightly upregulated in Raji cells. The engagement of CD40 by sCD40L enhanced CD95 expression, but the level of CM1 expression was unchanged in Ramos. However, sCD40L downregulated both CD95 and CM1 expression in Raji. In addition, the caspase-8 specific inhibitor blocked CM1-induced apoptosis in Ramos cells, but not in Raji cells. Increased mitochondrial membrane permeabilization was observed only in Raji cells. Moreover, the effector caspase inhibitor, z-DEVD, blocked CM1-mediated apoptosis in both cell lines. We found that CM1-induced apoptosis is achieved via different initiation pathways, which are cell-type dependent. 相似文献