全文获取类型
收费全文 | 1890篇 |
免费 | 130篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 31篇 |
儿科学 | 101篇 |
妇产科学 | 109篇 |
基础医学 | 219篇 |
口腔科学 | 57篇 |
临床医学 | 181篇 |
内科学 | 366篇 |
皮肤病学 | 47篇 |
神经病学 | 40篇 |
特种医学 | 153篇 |
外科学 | 133篇 |
综合类 | 136篇 |
预防医学 | 105篇 |
眼科学 | 15篇 |
药学 | 132篇 |
1篇 | |
中国医学 | 74篇 |
肿瘤学 | 133篇 |
出版年
2021年 | 19篇 |
2020年 | 13篇 |
2018年 | 21篇 |
2017年 | 26篇 |
2016年 | 22篇 |
2015年 | 40篇 |
2014年 | 55篇 |
2013年 | 57篇 |
2012年 | 67篇 |
2011年 | 62篇 |
2010年 | 64篇 |
2009年 | 61篇 |
2008年 | 64篇 |
2007年 | 75篇 |
2006年 | 58篇 |
2005年 | 47篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 28篇 |
2001年 | 44篇 |
2000年 | 31篇 |
1999年 | 36篇 |
1998年 | 50篇 |
1997年 | 58篇 |
1996年 | 50篇 |
1995年 | 43篇 |
1994年 | 56篇 |
1993年 | 35篇 |
1992年 | 16篇 |
1991年 | 20篇 |
1990年 | 18篇 |
1989年 | 29篇 |
1988年 | 29篇 |
1987年 | 34篇 |
1986年 | 29篇 |
1985年 | 17篇 |
1984年 | 21篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1959年 | 35篇 |
1958年 | 58篇 |
1957年 | 87篇 |
1956年 | 45篇 |
1955年 | 75篇 |
1954年 | 67篇 |
1953年 | 17篇 |
1952年 | 14篇 |
1949年 | 10篇 |
排序方式: 共有2033条查询结果,搜索用时 0 毫秒
1.
Abstract: This paper dicusses the use of esophageal dilatation with a Rigiflex TTS balloon. This method was used 45 times on 11 patients affected by anastomotic or a severe grade peptic esophageal stenosis. Fluoroscopic guidance was used in 36 procedures (80%) without effecting the mean duration of the treatment (12 minutes). The results were considered satisfactory when these goals had been achieved: a) dilatation of the stenosis over 15 mm; b) a dysphagia free-time of more than 6 months. A satisfactory result was achieved in 10 patients (90.9%), without deaths and major complications. 5 patients received 1 dilatation and the other 5 needed, 3-3-4-7–11 procedures respectively to obtain a satisfactory result. On these basis we consider that its great efficacy, security and tolerability depend on the following characteristics of the Rigiflex TTS balloon: 1) “radial” dilatation; 2) the possibility of introducing the balloon through the operative channel of the fiberscope; 3) direct visualization of the stenosis during dilatation. The following disadvantages with this method are: the absence of a tactile sensation of dilatation and the elevated cost of the instrument. We conclude that the Rigiflex TTS balloon is an important alternative to guide-wire techniques, especially for the treatment of severe esophageal strictures. 相似文献
2.
3.
Anulus fibrosus in bulging intervertebral disks 总被引:1,自引:0,他引:1
In this investigation the association of radial tears of the anulus fibrosus and bulging of the intervertebral disk was studied. An index of disk bulging was measured in sagittal anatomic sections in 149 lumbar disks from 31 cadavers. The indexes of disk bulging were correlated with stages of disk development and the presence of an annular tear. The largest disk-bulging indexes were always associated with radial tears of the anulus. Eighty-four percent of the disks with radial tears had disk-bulging indexes greater than 2.5 mm. Most normal adult disks had an index of less than 2.5 mm. The results challenge the concept that the anulus fibrosus is intact in bulging disks, although ruptured in herniated disks. 相似文献
4.
5.
6.
Policosanol is a new cholesterol-lowering drug isolated and purified from sugar-cane wax. which prevents the development of lipofundin-induced lesions and foam-cell formation in New Zealand rabbits and Wistar rats. This study was conducted to examine the effects of policosanol on foam-cell formation in carrageenan-induced granulomas in rats. Eighteen Wistar rats were randomly distributed in three experimental groups which received orally for 20 days Tween 20 H2O as vehicle (control group) or policosanol at 2.5 or 25 mg kg?1. At the 11th day. lipofundin was injected intrapcritoneally for 8 days to induce formation of foam cells in the granuloma. At day 13, carrageenan was injected subcutaneously for granuloma induction and seven days later animals were killed. A significant reduction of the foam-cell formation in granulomas of policosanol-treated rats was observed. It is concluded that policosanol prevents the development of foam cells in carrageenan-induced granulomas (extravascular medium) in rats. 相似文献
7.
Twelve Sardinian patients affected by histologically defined classic Kaposi's sarcoma (KS) were HLA-A, B, C and DR typed. Compared to 220 age and ethnically matched healthy controls, KS patients showed a significant increase in HLA-DR5 (66.6 vs 23.1%, P less than 0.001) and a considerable decrease in HLA-DR3 (8.3 vs 53.6%, P = 0.0055). No definite association was observed for other HLA antigens. These results confirm the existence of an HLA associated genetic control of KS susceptibility and support the hypothesis that HLA-DR5 plays the role of a predisposition marker while HLA-DR3 bears a genetic resistance to the disease. 相似文献
8.
Z. H. Li L. A. Aaltonen Q. Shu S. Srivastava W. E. Grizzle D. Shibata 《The American journal of pathology》1996,148(6):1757-1761
The detection of somatic microsatellite (MS) alterations in tumors is often interpreted as a sign of underlying genomic instability. However, it is unclear why the proportions of altered MS loci vary between different mutator phenotype tumors. We present a simple mathematical analysis that can account for some of these differences, recognizing that the mutations accumulated in a tumor reflect both its mutation rate and number of cell divisions. Only a small proportion of mutated MS loci are expected in tumors with normal or low mutation rates. In contrast, tumors with high mutation rates may or may not acquire mutations depending on the numbers of divisions that proceed the onset of the mutator phenotype. The majority of MS loci should accumulate mutations if high mutation rates are acquired early in tumor progression. Somatic MS mutations provide clues to both the mode and tempo of tumori-genesis. 相似文献
9.
PTEN mutational spectra,expression levels,and subcellular localization in microsatellite stable and unstable colorectal cancers 总被引:9,自引:0,他引:9 下载免费PDF全文
Zhou XP Loukola A Salovaara R Nystrom-Lahti M Peltomäki P de la Chapelle A Aaltonen LA Eng C 《The American journal of pathology》2002,161(2):439-447
PTEN on 10q23.3 encodes a dual-specificity phosphatase that negatively regulates the phosphoinositol-3-kinase/Akt pathway and mediates cell-cycle arrest and apoptosis. Germline PTEN mutations cause Cowden syndrome and a range of several different hamartoma-tumor syndromes. Hereditary nonpolyposis colon cancer (HNPCC) syndrome is characterized by germline mutations in the mismatch repair (MMR) genes and by microsatellite instability (MSI) in component tumors. Although both colorectal carcinoma and endometrial carcinoma are the most frequent component cancers in HNPCC, only endometrial cancer has been shown to be a minor component of Cowden syndrome. We have demonstrated that somatic inactivation of PTEN is involved in both sporadic endometrial cancers and HNPCC-related endometrial cancers but with different mutational spectra and different relationships to MSI. In the current study, we sought to determine the relationship of PTEN mutation, 10q23 loss of heterozygosity, PTEN expression, and MSI status in colorectal cancers (CRCs). Among 11 HNPCC CRCs, 32 MSI+ sporadic cancers, and 39 MSI- tumors, loss of heterozygosity at 10q23.3 was found in 0%, 8%, and 19%, respectively. Somatic mutations were found in 18% (2 of 11) of the HNPCC CRCs and 13% (4 of 32) of the MSI+ sporadic tumors, but not in MSI- cancers (P = 0.015). All somatic mutations occurred in the two 6(A) coding mononucleotide tracts in PTEN, suggestive of the etiological role of the deficient MMR. Immunohistochemical analysis revealed 31% (14 of 45) of the HNPCC CRCs and 41% (9 of 22) of the MSI+ sporadic tumors with absent or depressed PTEN expression. Approximately 17% (4 of 23) of the MSI- CRCs had decreased PTEN expression, and no MSI- tumor had complete loss of PTEN expression. Among the five HNPCC or MSI+ sporadic CRCs carrying frameshift somatic mutations with immunohistochemistry data, three had lost all PTEN expression, one showed weak PTEN expression levels, and one had mixed tumor cell populations with weak and moderate expression levels. These results suggest that PTEN frameshift mutations in HNPCC and sporadic MSI+ tumors are a consequence of mismatch repair deficiency. Further, hemizygous deletions in MSI- CRCs lead to loss or reduction of PTEN protein levels and contribute to tumor progression. Finally, our data also suggest that epigenetic inactivation of PTEN, including differential subcellular compartmentalization, occurs in CRCs. 相似文献
10.
Astrid LA. Kuijpers Rolph Pfundt Patrick LJM Zeeuwen Henri OF. Molhuizen Edwin CM. Mariman Peter CM. van de Kerkhof Joost Schalkwijk 《Clinical genetics》1998,54(1):96-101
Psoriasis is a multifactorial skin disease characterised by epidermal abnormalities and infiltration by lymphocytes and polymorphonuclear leukocytes (PMN). Skin-derived antileukoproteinase (SKALP), also known as elafin, is a potent inhibitor of human leukocyte elastase and proteinase 3, two PMN-derived proteinases implicated in tissue destruction and leukocyte migration. We have shown that, at least at the protein level, SKALP is significantly decreased in lesional skin of patients with pustular psoriasis compared with plaque-type psoriasis. This finding raised the possibility that SKALP could be one of the candidate genes for pustular forms of psoriasis. We therefore performed single strand conformation polymorphism (SSCP) analysis on the SKALP gene to screen for mutations/polymorphisms in the exons of 30 patients with plaque-type psoriasis, 15 patients with pustular psoriasis and 48 healthy controls. In exon 1 a polymorphism was detected at position + 43 relative to the translation start site, resulting in a substitution of threonine for alanine in the signal peptide. In the promoter region a dinucleotide repeat polymorphism was identified. Both polymorphisms were not associated with pustular psoriasis, or psoriasis in general. Our data indicate that the decrease in SKALP activity in pustular psoriasis is not caused by mutations in the coding region of the gene, and that there is no allelic association between pustular psoriasis and SKALP gene polymorphisms. 相似文献