全文获取类型
收费全文 | 589篇 |
免费 | 47篇 |
国内免费 | 105篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 28篇 |
妇产科学 | 4篇 |
基础医学 | 63篇 |
口腔科学 | 32篇 |
临床医学 | 122篇 |
内科学 | 179篇 |
皮肤病学 | 6篇 |
神经病学 | 10篇 |
特种医学 | 70篇 |
外科学 | 69篇 |
综合类 | 38篇 |
预防医学 | 13篇 |
眼科学 | 5篇 |
药学 | 54篇 |
中国医学 | 1篇 |
肿瘤学 | 46篇 |
出版年
2021年 | 4篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 11篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 18篇 |
2009年 | 17篇 |
2008年 | 4篇 |
2007年 | 60篇 |
2006年 | 15篇 |
2005年 | 33篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 18篇 |
1999年 | 7篇 |
1998年 | 46篇 |
1997年 | 37篇 |
1996年 | 41篇 |
1995年 | 20篇 |
1994年 | 24篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 7篇 |
1990年 | 17篇 |
1989年 | 21篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1968年 | 3篇 |
排序方式: 共有741条查询结果,搜索用时 15 毫秒
81.
Bouvet M Nardin SR Burton DW Lee NC Yang M Wang X Baranov E Behling C Moossa AR Hoffman RM Deftos LJ 《Pancreas》2002,24(3):284-290
INTRODUCTION: Parathyroid hormone-related protein (PTHrP) can act as an oncoprotein to regulate the growth and proliferation of many common malignancies, including pancreatic cancer. Previous studies have shown that PTHrP is produced by human pancreatic cancer cell lines, can be shown in the cytoplasm and nucleus of paraffin-embedded pancreatic adenocarcinoma tumor specimens, and is secreted into the media of cultured pancreatic adenocarcinoma cells. We hypothesized that PTHrP could serve as a tumor-marker for growth of pancreatic cancer in vivo. AIM AND METHODOLOGY: To test this hypothesis, we used an orthotopic model developed in our laboratory of the PTHrP-producing human pancreatic cancer line, BxPC-3. This tumor was stably transduced with green fluorescence protein (GFP) to facilitate visualization of tumor growth and metastases. At early (5 weeks) and late (13 weeks) time points after surgical orthotopic implantation, serum PTHrP was measured and primary and metastatic tumor burden was determined for each mouse by assessing GFP expression. RESULTS: By 5 weeks after surgical orthotopic implantation (early group), the mean serum PTHrP level was 33.3 pg/mL. In contrast, by 13 weeks after surgical orthotopic implantation (late group), the mean serum PTHrP level increased to 158.5 pg/mL. These differences were highly significant (p < 0.001, Student t test). Numerous metastatic lesions were readily visualized by GFP in the late group. Serum PTHrP levels measured by immunoassay correlated with primary pancreatic tumor weights and serum calcium levels (p <0.01). PTHrP levels were not detectable (<21 pg/mL) in any of the 10 control mice with no tumor. Western blotting of BxPC-3-GFP tumor lysates confirmed the presence of PTHrP. BxPC-3-GFP tumor tissue stained with antibody to PTHrP. CONCLUSION: These results indicate that PTHrP can serve as a tumor marker in animal models of pancreatic cancer and may be a useful tumor marker for clinical pancreatic adenocarcinoma. 相似文献
82.
Jochim S Terhaar sive Droste Mike E Craanen Rene WM van der Hulst Joep F Bartelsman Dick P Bezemer Kim R Cappendijk Gerrit A Meijer Linde M Morsink Pleun Snel Hans ARE Tuynman Roy LJ van Wanrooy Eric IC Wesdorp Chris JJ Mulder 《World journal of gastroenterology : WJG》2009,15(9):1085-1092
AIM: To assess the prevalence and location of advanced neoplasia in patients undergoing colonoscopy, and to compare the yield per indication. METHODS: In a multicenter colonoscopy survey (n = 18 hospitals) in the Amsterdam area (Northern Holland), data of all colonoscopies performed during a three month period in 2005 were analyzed. The location and the histological features of all colonic neoplasia were recorded. The prevalence and the distribution of advanced colorectal neoplasia and differences in yield between indication clusters were evaluated. Advanced neoplasm was defined as adenoma 〉 10 mm in size, with 〉 25% villous features or with high-grade dysplasia or cancer. RESULTS: A total of 4623 eligible patients underwent a total colonoscopy. The prevalence of advanced neoplasia was 13%, with 281 (6%) adenocarcinomas and 342 (7%) advanced adenomas. Sixty-seven percent and 33% of advanced neoplasia were located in the distal and proximal colon, respectively. Of all patients with right-sided advanced neoplasia (n = 228), 51% had a normal distal colon, whereas 27% had a synchronous distal adenoma. Ten percent of all colonoscopies were performed in asymptomatic patients, 7% of whom had advanced neoplasia. In the respective procedure indication clusters, the prevalence of rightsided advanced neoplasia ranged from 11%-57%. CONCLUSION: One out of every 7-8 colonoscopies yielded an advanced colorectal neoplasm. Colonoscopy is warranted for the evaluation of both symptomatic and asymptomatic patients. 相似文献
83.
Chlorpropamide-induced pure white cell aplasia 总被引:2,自引:0,他引:2
We investigated the mechanism for isolated agranulocytosis and marrow pure white cell aplasia in an elderly man receiving 0.5 to 1.0 g per day of chlorpropamide (Chl) without other toxic drug exposure or overt systemic illness. Patient marrow revealed an absence of recognizable granulocytic precursors; megakaryocytes and erythroid precursors were normal. The WBC count was 1800/mm3 on admission with only 2% neutrophils; the absolute neutrophil count first exceeded 500/mm3 on the 17th day following cessation of Chl. A serum Chl level on admission was 100 micrograms/mL (acute phase, AP); no Chl was detected in serum (convalescent phase, CP) assessed on the 22nd hospital day. Antineutrophil antibodies were not detected, and T cell depletion failed to augment patient in vitro granulopoiesis. Patient AP serum produced potent complement-mediated inhibition (87% +/- 7%) of autologous granulocyte progenitors (CFU-GM) with minimal inhibition of erythroid (11% +/- 5%) or multipotent (5% +/- 4%) progenitor cells. Selective inhibition by patient AP serum of CFU-GM (74% +/- 11%) was also seen against two allogeneic marrows. Patient CP serum no longer inhibited (6% +/- 4%) autologous CFU-GM. Addition of Chl (5 to 120 micrograms/mL) to CP serum but not to control serum resulted in potent drug concentration-dependent complement-mediated inhibition of autologous and allogeneic CFU-GM. Inhibition of CFU-GM in the presence of Chl was no longer demonstrable following immunoabsorbent removal of IgG from patient serum. Patient serum in the presence of Chl had limited activity against morphologically recognizable marrow granulocytic precursors in a microimmunofluorescence assay. These results are most consistent with the development of Chl-dependent, selective antibody-mediated immune inhibition of granulopoiesis. 相似文献
84.
Using behavioural insights to increase HIV self‐sampling kit returns: a randomized controlled text message trial to improve England's HIV self‐sampling service 下载免费PDF全文
Objectives
The aim of the study was to determine whether behaviourally informed short message service (SMS) primer and reminder messages could increase the return rate of HIV self‐sampling kits ordered online.Methods
The study was a 2 × 2 factorial design randomized control trial. A total of 9585 individuals who ordered a self‐sampling kit from www.freetesting.hiv different SMS combinations: 1) standard reminders sent days 3 and 7 after dispatch (control); 2) primer sent 1 day after dispatch plus standard reminders; 3) behavioural insights (BI) reminders (no primer); or 4) primer plus BI reminders. The analysis was restricted to individuals who received all messages (n = 8999). We used logistic regression to investigate independent effects of the primer and BI reminders and their interaction. We explored the impact of sociodemographic characteristics on kit return as a secondary analysis.Results
Those who received the primer and BI reminders had a return rate 4% higher than that of those who received the standard messages. We found strong evidence of a positive effect of the BI reminders (odds ratio 1.13; 95% confidence interval 1.04–1.23; P = 0.003) but no evidence for an effect of the primer, or for an interaction between the two interventions. Odds of kit return increased with age, with those aged ≥ 65 years being almost 2.5 times more likely to return the kit than those aged 25–34 years. Men who have sex with men were 1.5–4.5 times more likely to return the kit compared with other sexual behaviour and gender identity groups. Non‐African black clients were 25% less likely to return the kit compared with other ethnicities.Conclusions
Adding BI to reminder messages was successful in improving return rates at no additional cost. 相似文献85.
Oral cyclophosphamide versus chlorambucil in the treatment of patients with membranous nephropathy and renal insufficiency 总被引:4,自引:1,他引:4
Branten AJ; Reichert LJ; Koene RA; Wetzels JF 《QJM : monthly journal of the Association of Physicians》1998,91(5):359-366
We treated patients with idiopathic membranous nephropathy (iMGN) and renal
insufficiency, using: (i) (n = 15) monthly cycles of steroids (1 g
methyl-prednisolone i.v. on three consecutive days, followed by oral
prednisone 0.5 mg/kg/day months 1, 3 and 5) and chlorambucil (0.15
mg/kg/day months 2, 4 and 6); or (ii) (n = 17) oral cyclophosphamide
(1.5-2.0 mg/kg/day for 1 year) and steroids in a comparable dose. The
groups were comparable in age, renal function and levels of proteinuria.
During the 6 months preceding treatment, serum creatinine levels increased
from 148 +/- 50 to 219 +/- 73 mumol/l in the chlorambucil group and from
164 +/- 86 to 274 +/- 126 mumol/l in the cyclophosphamide group. Median
(range) follow-ups were: chlorambucil 38 months (8-71); cyclophosphamide 26
months (5-68) (NS). Renal function improved in both groups, but the
improvement was short-lived in the chlorambucil group; 12 months after
starting treatment, mean serum creatinine was 6.3 mumol/l lower in the
chlorambucil group and 121 mumol/l lower in the cyclophosphamide group (p
< 0.01). Four chlorambucil-treated patients developed ESRD, and five
needed a second course of therapy, whereas only one
cyclophosphamide-treated patient developed ESRD (p < 0.05). Remissions
of proteinuria occurred more frequently after cyclophosphamide treatment
(15/17 vs. 5/15; p < 0.01). Side-effects necessitated interruption of
treatment in six patients on cyclophosphamide and in 11 on chlorambucil (p
< 0.05). In our patients, oral cyclophosphamide was better tolerated
than oral chlorambucil. The suggested greater efficacy of the oral
cyclophosphamide regimen needs to be ascertained by longer follow-up.
相似文献
86.
87.
Background.?Hypercalcemia is an uncommon complication of disseminated granulomatous infections. The pathogenesis of hypercalcemia associated with infection is not clear. Methods.?We investigated a case of disseminated coccidioidomycosis with hypercalcemia. We used a sensitive radioimmunoassay to measure serum parathyroid hormone-related peptide (PTHrP) and a mouse monoclonal antibody to PTHrP to immunostain biopsies. Results.?We found elevated serum levels of PTHrP while the patient was hypercalcemic that became undetectable when serum calcium normalized. We also found that the inflammatory cells and some surrounding tissues in skin biopsies expressed PTHrP. PTHrP was expressed by all biopsied lesions of patients with coccidioidomycosis that we examined, whether localized to the lung or disseminated, but no other cases were hypercalcemic. PTHrP was also expressed by the 3 mycobacterial granulomas we examined, and in a lymph node from a patient with sarcoidosis. Conclusions.?The expression of PTHrP is a property of infectious granulomas regardless of etiology or the tissue involved, suggesting that PTHrP expression is part of the normal granulomatous immune response. Hypercalcemia may result if there is disseminated infection and multiple granulomas. We propose that excess production of PTHrP is the cause of hypercalcemia in granulomatous infections. 相似文献
88.
Abruzzo LV; Schmidt K; Weiss LM; Jaffe ES; Medeiros LJ; Sander CA; Raffeld M 《Blood》1993,82(1):241-246
We describe a patient with angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), who subsequently developed large-cell immunoblastic lymphoma of B-cell immunophenotype. At the time of the initial diagnosis, histologic examination of an inguinal lymph node showed typical features of AILD, and there was no evidence of a monoclonal B-cell population by immunohistochemical analysis. In situ hybridization and Southern blot analysis for Epstein-Barr virus (EBV) were negative. At autopsy 2 years later, the patient had widespread lymph node and organ involvement by large-cell immunoblastic lymphoma of B-cell immunophenotype. Southern blot analysis performed on DNA extracted from lymph nodes, liver, and spleen showed two patterns of Ig heavy chain and kappa light chain gene rearrangements. The T-cell receptor beta chain gene was in the germline configuration. Analysis with an EBV terminal repeat region probe showed two clonal populations that paralleled the Ig gene rearrangement studies. Double-labeling immunohistochemistry and in situ hybridization confirmed the presence of EBV within the neoplastic B cells. The data support the hypothesis that EBV was not etiologically related to AILD in this case, and that EBV proliferation may occur after the onset of the disease. Further, the data suggest that some B-cell lymphomas that arise in the setting of AILD resemble EBV-associated B-cell lymphomas that arise in other immunodeficiency states. 相似文献
89.
Transfected leukocyte integrin CD11b/CD18 (Mac-1) mediates phorbol ester-activated, homotypic cell:cell adherence in the K562 cell line 总被引:1,自引:0,他引:1
Hickstein DD; Grunvald E; Shumaker G; Baker DM; Back AL; Embree LJ; Yee E; Gollahon KA 《Blood》1993,82(8):2537-2545
The CD11b/CD18 leukocyte integrin molecule mediates diverse neutrophil adherence-related functions, including cell:cell and cell:extracellular matrix attachments. To study the individual role of this leukocyte integrin in cell adherence in hematopoietic cells, we expressed the CD11b/CD18 complex on the surface of K562 cells, a cell line derived from an individual with chronic myelogenous leukemia in blast crisis. We used an amphotrophic retroviral vector designated LCD18SN, harboring the complete coding sequence for the CD18 subunit, to transfer the CD18 cDNA into K562 cells and select stable cell lines. The CD11b subunit in the expression plasmid pREP4 was transfected into these K562/CD18 cells by electroporation and stable cell clones were selected. These K562 cells possessed RNA and intracellular protein for each subunit, and they expressed the CD11b/CD18 heterodimer on the cell surface. When CD11b/CD18 expressing K562 cells were stimulated with phorbol myristate acetate (50 ng/mL) for 24 to 48 hours, these K562 cells formed dense cell:cell aggregates. This homotypic aggregation required both activation of the CD11b/CD18 complex and the induction of the counter- receptor for CD11b/CD18 on the conjugate cell. This cell line will (1) enable the structure-function relationships between cell activation and homotypic adherence to be assessed, (2) provide the opportunity to identify accessory molecules required for activation of the CD11b/CD18 complex, and (3) facilitate the identification of novel ligands for the CD11b/CD18 complex. 相似文献