全文获取类型
收费全文 | 185926篇 |
免费 | 8002篇 |
国内免费 | 395篇 |
专业分类
耳鼻咽喉 | 2482篇 |
儿科学 | 5632篇 |
妇产科学 | 4154篇 |
基础医学 | 26534篇 |
口腔科学 | 6012篇 |
临床医学 | 10796篇 |
内科学 | 41253篇 |
皮肤病学 | 5154篇 |
神经病学 | 15092篇 |
特种医学 | 4905篇 |
外国民族医学 | 1篇 |
外科学 | 21878篇 |
综合类 | 899篇 |
一般理论 | 36篇 |
预防医学 | 21670篇 |
眼科学 | 5055篇 |
药学 | 14241篇 |
1篇 | |
中国医学 | 777篇 |
肿瘤学 | 7751篇 |
出版年
2023年 | 948篇 |
2021年 | 2875篇 |
2020年 | 1588篇 |
2019年 | 3315篇 |
2018年 | 5878篇 |
2017年 | 3606篇 |
2016年 | 3551篇 |
2015年 | 3833篇 |
2014年 | 4233篇 |
2013年 | 6679篇 |
2012年 | 11581篇 |
2011年 | 12399篇 |
2010年 | 6101篇 |
2009年 | 4321篇 |
2008年 | 10136篇 |
2007年 | 10852篇 |
2006年 | 10321篇 |
2005年 | 9982篇 |
2004年 | 9225篇 |
2003年 | 8704篇 |
2002年 | 8225篇 |
2001年 | 5726篇 |
2000年 | 6579篇 |
1999年 | 4713篇 |
1998年 | 939篇 |
1996年 | 652篇 |
1992年 | 2286篇 |
1991年 | 2055篇 |
1990年 | 2042篇 |
1989年 | 1761篇 |
1988年 | 1683篇 |
1987年 | 1557篇 |
1986年 | 1596篇 |
1985年 | 1513篇 |
1984年 | 1092篇 |
1983年 | 945篇 |
1979年 | 1222篇 |
1978年 | 836篇 |
1977年 | 818篇 |
1976年 | 777篇 |
1975年 | 898篇 |
1974年 | 1128篇 |
1973年 | 1179篇 |
1972年 | 1110篇 |
1971年 | 1082篇 |
1970年 | 1011篇 |
1969年 | 1085篇 |
1968年 | 1111篇 |
1967年 | 983篇 |
1966年 | 881篇 |
排序方式: 共有10000条查询结果,搜索用时 301 毫秒
991.
A 51-year-old woman was admitted for a painless enlargement of the thyroid lasting over 6 months. Hashimoto's thyreoiditis was diagnosed and three tumors were found: oncocytic carcinoma, malignant lymphoma and papillary carcinoma. In the right lobe, oncocytic carcinoma and high grade malignant lymphoma composed of cells with irregular, lobulated nuclei were found. The lymphoma was confined to the thyroid gland. The oncocytic carcinoma invaded the capsule and the surrounding tissues. In the left lobe, there was a papillary carcinoma. 相似文献
992.
Transmission of Pneumocystis carinii DNA from a patient with P. carinii pneumonia to immunocompetent contact health care workers 总被引:1,自引:0,他引:1
Vargas SL Ponce CA Gigliotti F Ulloa AV Prieto S Muñoz MP Hughes WT 《Journal of clinical microbiology》2000,38(4):1536-1538
The transmission of Pneumocystis carinii from person to person was studied by detecting P. carinii-specific DNA in prospectively obtained noninvasive deep-nasal-swab samples from a child with a documented P. carinii pneumonia (PCP), his mother, two contact health care workers, and 30 hospital staff members who did not enter the patient's room (controls). Nested-DNA amplification was done by using oligonucleotide primers designed for the gene encoding the mitochondrial large subunit rRNA of rat P. carinii (P. carinii f. sp. carinii) that amplifies all forms of P. carinii and internal primers specific for human P. carinii (f. sp. hominis). P. carinii f. sp. hominis DNA was detected in samples from the patient and all of his contacts versus none of the 30 hospital staff members. The results, as previously shown in murine models of P. carinii pneumonia, document that person-to-person transmission of P. carinii is possible. This observation suggests that immunocompromised patients not on PCP prophylaxis should not enter the room of a patient with PCP, and it also raises the question as to whether healthy contacts can transmit the disease to immunocompromised patients at risk. 相似文献
993.
Inogés S Merino J Bandrés E De Castro P Subirá ML Sánchez-Ibarrola A 《Clinical and experimental immunology》1999,115(3):521-525
In this study we have examined intracellular cytokines in peripheral blood mononuclear cells (PBMC) of MS patients by flow cytometry (cytokine flow cytometry). MS progressive patients showed an increased number of cells producing interferon-gamma (IFN-gamma) after activation with phorbol 12-myristate 13-acetate and ionomycin, compared with patients with clinically inactive forms (P < 0001) and with healthy controls (P = 0001). These cells belonged to the CD4+ and CD8+ subsets in similar proportions. Clinically inactive patients showed a lower level of cells producing IL-2 than controls (P = 0.03) and active MS patients (P = 0.03). Most IL-2-producing cells were CD4+ lymphocytes, although a small part of the IL-2 was also produced by CD8+ cells. The percentage of cells producing simultaneously IL-2 and IFN-gamma was increased in active MS and they were mainly CD4+ lymphocytes. No differences in the production of IL-4 were observed between groups. However, we found an increased IL-10 production in clinically active MS patients (P = 0.03). Treatment with IFN-beta of active MS patients showed lower levels of cytokines when compared with untreated MS patients. This methodological approach could help in the follow up and therapeutic monitoring of MS patients. 相似文献
994.
Péter Várnai Gábor L. Petheö Judit K. Makara András Spät 《Pflügers Archiv : European journal of physiology》1998,435(3):429-431
Elevation of extracellular potassium concentration by as little as some tenth of mM activates rat adrenal glomerulosa cells.
In the present study some factors responsible for this high K+ sensitivity were examined. Using whole-cell voltage-clamp technique we found that both T-type and L-type voltage-dependent
Ca2+ channels have very low threshold potential (–71 and –58 mV, resp.). By means of patch-clamp technique combined with single-cell
fluorimetry we also provided evidence that the activation of Igl, a K+-activated inward rectifying current is associated with Ca2+ influx. Both the low activation threshold of voltage-dependent Ca2+ channels and the function of Igl contribute to the exceptional K+ sensitivity of the glomerulosa cells.
Received: 30 September 1997 / Accepted: 4 November 1997 相似文献
995.
Summary For the investigation of epitope composition of different adenovirus hexon types sixty-one mouse ascitic fluids containing monoclonal antibodies (MAbs) developed in three different panels were used. The distinction and marking of the different epitopes recognized by the MAbs were carried out by the determination of the composite cross-reactivity pattern, the titer and the correlation coefficient of all the 61 MAbs with 21 different hexon types representing all the six human subgenera, as well as different bovine and simian adenoviruses. The distinct epitopes were marked by two numbers refering the homologous hexon type to which the MAbs were directed and the serial number of the epitope specified by the different members of the given panel of the MAbs. The three panels of MAbs recognized 22 epitopes on the 21 hexon types among them a genus and three type specific ones and 18 different bi- and multilateral intertype (IT) specific epitopes that grouped adenoviruses within the genus, independently from the subgenus they belong to. Considering that the type specific epitope could be present only on the homologous hexon type, the largest number of the different epitopes distinguishable by the MAbs used could be 20 on the homologous hexon and 19 on the heterologous ones. It was found that the total number of IT specific epitopes on the hexons varied between 2 and 18. The distribution of the distinct specific epitopes on the different hexon types was different, as expected. The antigenic structure of the individual hexon types were characterized by the determination of their IT specific epitope spectrum. By pairwise analysis ten human hexon types formed three epitope clusters (types 4 and 19; types 8, 9, 9/13 and 10; as well as all types of subgenus C) showing identical epitope spectra. No clustering was found with human type 7, 12, 13, 18, 26, 27, 35 and 41, as well as with bovine and simian adenovirus hexons studied. However, they displayed a closer or looser antigenic relationship among each other and to members of the epitope clusters. The degree of antigenic relationship could be expressed by the similarity/dissimilarity percentage calculated from the number of the identical and different epitopes present on any two given hexon types. 相似文献
996.
Krustrup P Söderlund K Mohr M González-Alonso J Bangsbo J 《Pflügers Archiv : European journal of physiology》2004,449(1):56-65
To investigate recruitment of slow-twitch (ST) and fast-twitch (FT) muscle fibres, as well as the involvement of the various quadriceps femoris muscle portions during repeated, intense, one-legged knee-extensor exercise, 12 healthy male subjects performed two 3-min exercise bouts at ~110% maximum thigh O2 consumption (EX1 and EX2) separated by 6 min rest. Single-fibre metabolites were determined in successive muscle biopsies obtained from the vastus lateralis muscle (n=6) and intra-muscular temperatures were continuously measured at six quadriceps muscle sites (n=6). Creatine phosphate (CP) had decreased (P<0.05) by 27, 73 and 88% in ST fibres and 25, 71 and 89% in FT fibres after 15 and 180 s of EX1 and after 180 s of EX2, respectively. CP was below resting mean–1 SD in 15, 46, 84 and 100% of the ST fibres and 9, 48, 85 and 100% of the FT fibres at rest, after 15 and 180 s of EX1 and after 180 s of EX2, respectively. A significant muscle temperature increase (Tm) occurred within 2–4 s at all quadriceps muscle sites. Tm varied less than 10% between sites during EX1, but was 23% higher (P<0.05) in the vastus lateralis than in the rectus femoris muscle during EX2. Tm in the vastus lateralis was 101 and 109% of the mean quadriceps value during EX1 and EX2, respectively. We conclude that both fibre types and all quadriceps muscle portions are recruited at the onset of intense knee-extensor exercise, that essentially all quadriceps muscle fibres are activated during repeated intense exercise and that metabolic measurements in the vastus lateralis muscle provide a good indication of the whole-quadriceps muscle metabolism during repeated, intense, one-legged knee-extensor exercise. 相似文献
997.
de Astorza B Cortés G Crespí C Saus C Rojo JM Albertí S 《Infection and immunity》2004,72(3):1767-1774
The airway epithelium represents a primary site for contact between microbes and their hosts. To assess the role of complement in this event, we studied the interaction between the A549 cell line derived from human alveolar epithelial cells and a major nosocomial pathogen, Klebsiella pneumoniae, in the presence of serum. In vitro, we found that C3 opsonization of poorly encapsulated K. pneumoniae clinical isolates and an unencapsulated mutant enhanced dramatically bacterial internalization by A549 epithelial cells compared to highly encapsulated clinical isolates. Local complement components (either present in the human bronchoalveolar lavage or produced by A549 epithelial cells) were sufficient to opsonize K. pneumoniae. CD46 could competitively inhibit the internalization of K. pneumoniae by the epithelial cells, suggesting that CD46 is a receptor for the binding of complement-opsonized K. pneumoniae to these cells. We observed that poorly encapsulated strains appeared into the alveolar epithelial cells in vivo but that (by contrast) they were completely avirulent in a mouse model of pneumonia compared to the highly encapsulated strains. Our results show that bacterial opsonization by complement enhances the internalization of the avirulent microorganisms by nonphagocytic cells such as A549 epithelial cells and allows an efficient innate defense. 相似文献
998.
Development and comparison of enzyme immunoassays for diagnosis of Chagas' disease using fixed forms of Trypanosoma cruzi (Epimastigotes, Amastigotes, and Trypomastigotes) and assessment of antigen stability for the three assays 下载免费PDF全文
Berrizbietia M Ndao M Gottschalk M Aché A Vásquez F Lacouture S Medina M Ward BJ 《Journal of clinical microbiology》2004,42(4):1766-1769
Three enzyme immunoassays (EIAs) for diagnosis of Chagas' disease were developed with fixed forms of Trypanosoma cruzi using a panel of 435 sera from the following groups: Venezuelan subjects positive by immunofluorescence (n = 70), Venezuelan healthy controls (n = 85), healthy Canadians (n = 166), and subjects with other parasitic diseases (n = 114). All assays achieved 100% sensitivity and reasonable specificity for amastigotes (97.6%), epimastigotes (98.3%), and trypomastigotes (99.3%). The fixed-trypomastigote assay was stable over 4 months at 4 degrees C and room temperature. These data suggest that a fixed-trypomastigote EIA may be a suitable candidate for blood bank screening. 相似文献
999.
1000.
Guzmán-Cornejo C Morales-Malacara JB López-Ortega G 《Journal of medical entomology》2004,41(4):587-592
Eudutsbabekia choeronycteris new species was found on the phyllostomid bat, Choeronycteris mexicana Tschudi, in the central part of Mexico. The female, male, and larva are described and illustrated. 相似文献