全文获取类型
收费全文 | 2021篇 |
免费 | 122篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 196篇 |
妇产科学 | 120篇 |
基础医学 | 151篇 |
口腔科学 | 62篇 |
临床医学 | 228篇 |
内科学 | 375篇 |
皮肤病学 | 48篇 |
神经病学 | 62篇 |
特种医学 | 152篇 |
外科学 | 160篇 |
综合类 | 142篇 |
预防医学 | 175篇 |
眼科学 | 25篇 |
药学 | 111篇 |
1篇 | |
中国医学 | 74篇 |
肿瘤学 | 66篇 |
出版年
2021年 | 22篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 20篇 |
2017年 | 31篇 |
2016年 | 24篇 |
2015年 | 39篇 |
2014年 | 70篇 |
2013年 | 79篇 |
2012年 | 93篇 |
2011年 | 69篇 |
2010年 | 84篇 |
2009年 | 64篇 |
2008年 | 70篇 |
2007年 | 60篇 |
2006年 | 67篇 |
2005年 | 38篇 |
2004年 | 35篇 |
2003年 | 23篇 |
2002年 | 21篇 |
2001年 | 31篇 |
2000年 | 20篇 |
1999年 | 29篇 |
1998年 | 51篇 |
1997年 | 58篇 |
1996年 | 54篇 |
1995年 | 44篇 |
1994年 | 58篇 |
1993年 | 36篇 |
1992年 | 20篇 |
1991年 | 23篇 |
1990年 | 24篇 |
1989年 | 34篇 |
1988年 | 31篇 |
1987年 | 38篇 |
1986年 | 27篇 |
1985年 | 16篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 26篇 |
1980年 | 17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 |
排序方式: 共有2158条查询结果,搜索用时 15 毫秒
51.
Artifon EL Takada J Okawa L Ferreira F Santos M Moura EG Otoch JP Sakai P 《Revista de gastroenterologia de Mexico》2011,76(3):270-274
Biliary endoscopic drainage using metallic self-expanded stents has become a well-established method for palliative treatment of malignant biliary obstruction. However, its occlusion, mainly by tumor overgrowth, is still the main complication without a standard treatment. We here describe a new method of treatment for biliary metallic stent occlusion, through the echo guided biliary drainage. We present a 68-year-old patient with metastatic pancreatic cancer previously treated for jaundice with ERCP and self-expandable metallic stent insertion. Four weeks later, the patient developed jaundice and symptoms of gastric outlet obstruction. A new ERCP confirmed obstruction of the second portion of the duodenum, due to diffuse tumor growth. EUS was performed, and the previous metal biliary stent was seen occluded at the distal portion in the common bile duct. A EUS-guided choledocododenostomy was performed and then, an overlapping self-expanding metal enteral stent was placed through the malignant obstruction. There were no early complications and the procedure was also clinically effective in relieving jaundice and gastric outlet obstruction symptoms. If ERCP fails in the management of occluded biliary metallic stents, EUS biliary drain can provide effective biliary decompression and should be considered an alternative to other endoscopic techniques. 相似文献
52.
53.
54.
Michel Kahaleh Everson LA Artifon Manuel Perez-Miranda Monica Gaidhane Carlos Rondon Takao Itoi Marc Giovannini 《World journal of gastroenterology : WJG》2015,21(3):726-741
Endoscopic retrograde cholangiopancreatography(ERCP) is the preferred procedure for biliary and pancreatic drainage.While ERCP is successful in about 95% of cases,a small subset of cases are unsuccessful due to altered anatomy,peri-ampullary pathology,or malignant obstruction.Endoscopic ultrasound-guided drainage is a promising technique for biliary,pancreatic and recently gallbladder decompression,which provides multiple advantages over percutaneous or surgical biliary drainage.Multiple retrospective and some prospective studies have shown endoscopic ultrasoundguided drainage to be safe and effective.Based on the currently reported literature,regardless of the approach,the cumulative success rate is 84%-93% with an overall complication rate of 16%-35%.endoscopic ultrasoundguided drainage seems a viable therapeutic modality for failed conventional drainage when performed by highly skilled advanced endoscopists at tertiary centers with expertise in both echo-endoscopy and therapeutic endoscopy 相似文献
55.
56.
Global vascular expression of murine CD34, a sialomucin-like endothelial ligand for L-selectin 总被引:19,自引:2,他引:19
Extravasation of leukocytes into organized lymphoid tissues and into sites of inflammation is critical to immune surveillance. Leukocyte migration to peripheral lymph nodes (PLN), mesenteric lymph nodes (MLN) and Peyer's patches (PP) depends on L-selectin, which recognizes carbohydrate-bearing, sialomucin-like endothelial cell surface glycoproteins. Two of these ligands have been identified at the molecular level. One is the potentially soluble mucin, GlyCAM 1, which is almost exclusively produced by high endothelial venules (HEV) of PLN and MLN. The second HEV ligand for L-selectin is the membrane-bound sialomucin CD34. Historically, this molecule has been successfully used to purify human pluripotent bone marrow stem cells, and limited data suggest that human CD34 is present on the vascular endothelium of several organs. Here we describe a comprehensive analysis of the vascular expression of CD34 in murine tissues using a highly specific antimurine CD34 polyclonal antibody. CD34 was detected on vessels in all organs examined and was expressed during pancreatic and skin inflammatory episodes. A subset of HEV-like vessels in the inflamed pancreas of nonobese diabetic (NOD) mice are positive for both CD34 and GlyCAM 1, and bind to an L-selectin/immunoglobulin G (IgG) chimeric probe. Finally, we found that CD34 is present on vessels of deafferentiated PLN, despite the fact that these vessels are no longer able to interact with L-selectin or support lymphocyte binding in vitro or trafficking in vivo. Our data suggest that the regulation of posttranslational carbohydrate modifications of CD34 is critical in determining its capability to act as an L-selectin ligand. Based on its ubiquitous expression, we propose that an appropriately glycosylated form of vascular CD34 may act as a ligand for L-selectin-mediated leukocyte trafficking to both lymphoid and nonlymphoid sites. 相似文献
57.
Limited red blood cell (RBC) regeneration often prevents collection of sufficient blood from autologous donors. We studied the effects of subcutaneous recombinant erythropoietin (rEPO) in subjects making frequent blood donations. Six healthy iron-replete male subjects took rEPO (200 U/kg) subcutaneously daily, and donated blood (450 mL) twice a week for 3 weeks. During a control study, these subjects also attempted twice-weekly blood donations without rEPO. Four other males given rEPO, including one with idiopathic hemochromatosis, waited until day 8 to begin blood donations. All healthy subjects took oral ferrous sulfate. Subcutaneous rEPO given with blood donations resulted in a marked reticulocytosis (mean peak value 568 +/- 159 x 10(9)/L v 235 +/- 77 x 10(9)/L, control study; P < .05), and enhanced RBC production at 28 days (1,208 +/- 227 mL v 719 +/- 161 mL, P < .05). rEPO in advance of blood donations was slightly less effective in normal subjects (941 +/- 139 mL, P < .05); however, the subject with hemochromatosis produced substantially more RBCs (1,764 mL) than any normal subject. rEPO-treated normal subjects (but not the rEPO-treated patient with hemochromatosis or untreated controls) produced iron-deficient RBCs with elevated zinc protoporphyrin levels and low hemoglobin content. These cells appeared within 1 week of rEPO administration and before laboratory confirmation of depleted iron stores. Thus, subcutaneous rEPO is an effective stimulant of erythropoiesis in nonanemic blood donors. However, in addition to eventual depletion of iron stores, early functional iron deficiency affects response to the drug. 相似文献
58.
We have recently found that antibodies to L-selectin, the homing receptor on neutrophils, are as effective as those to beta 2-integrin at blocking formyl peptide-stimulated aggregation. Therefore, we investigated the requirements for expression of L-selectin and beta 2- integrin on adjacent cells during aggregation. Fluorescence flow cytometry allowed characterization of aggregates on the basis of size and color, as well as antibody binding to these two adhesive molecules. Formyl peptide-stimulated aggregate formation was measured for individual populations fluorescently labeled red (LDS-751) or green (CD44-FITC), and interpopulation red-green cell conjugates. Blocking either the beta 2-integrin or L-selectin adhesive epitope with monoclonal antibody on individual cell populations resulted in an approximately 50% reduction in two-color aggregation as compared with that in unblocked samples. Shedding the L-selectin on a cell population by preincubation with complexes of lipopolysaccharide and its plasma membrane binding protein also decreased aggregation to a control population by approximately 50%. We examined the aggregation of neutrophils from patients genetically deficient in beta 2-integrin and clinically leukocyte adhesion deficient (LAD). LAD adhesion to normal neutrophils was dependent on the expression of L-selectin on LAD cells and beta 2-integrin on normal cells. Thus, the minimum requirement for adhesion between two mixed populations of neutrophils was that one population expressed the beta 2-integrin and the other expressed the L- selectin adhesive epitope. 相似文献
59.
60.
The widespread assumption that cytoplasts generated from human polymorphonuclear leukocytes (PMNs) are vesicles consisting solely of cytoplasm surrounded by plasma membrane and devoid of granule activity remains to be tested. PMN cytoplasts were prepared by centrifugation of intact cells on a Ficoll step gradient in the presence of cytochalasin B. Two granule membrane markers, Mol, a fluorometrically detectable antigen, and cytochrome b, both of which have been shown to translocate to the plasma membrane during granule release, were compared for their activity in cytoplasts and intact PMNs. We found that the amount of Mol detected on the plasma membrane of intact PMNs, as compared with other membrane markers (such as antigens LFA-1 and beta 2m), increased 1.6- fold upon exposure of PMNs to Ficoll plus cytochalasin B prior to centrifugation. Another twofold increase in Mol expression occurred upon cytoplast preparation. Release of the granule enzymes, vitamin B12- binding protein, and lysozyme were also followed and correlated well (r = .78 and .92) with the amount of Mol antigen present on the cell surface. Cytochrome b was also found to be higher (1.4-fold) on plasma membranes isolated from cytoplasts than on plasma membranes isolated from intact control cells. These results indicate that some fusion of granule membranes and plasma membranes occurred during treatment of PMNs with Ficoll plus cytochalasin b and during cytoplast preparation. 相似文献