首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1203篇
  免费   66篇
  国内免费   7篇
耳鼻咽喉   19篇
儿科学   52篇
妇产科学   19篇
基础医学   148篇
口腔科学   32篇
临床医学   88篇
内科学   316篇
皮肤病学   15篇
神经病学   123篇
特种医学   37篇
外科学   185篇
综合类   5篇
预防医学   93篇
眼科学   11篇
药学   50篇
肿瘤学   83篇
  2023年   9篇
  2022年   11篇
  2021年   31篇
  2020年   15篇
  2019年   25篇
  2018年   38篇
  2017年   24篇
  2016年   28篇
  2015年   28篇
  2014年   43篇
  2013年   46篇
  2012年   68篇
  2011年   66篇
  2010年   50篇
  2009年   40篇
  2008年   73篇
  2007年   76篇
  2006年   49篇
  2005年   66篇
  2004年   48篇
  2003年   53篇
  2002年   49篇
  2001年   45篇
  2000年   29篇
  1999年   24篇
  1998年   11篇
  1997年   9篇
  1996年   6篇
  1995年   6篇
  1994年   6篇
  1992年   17篇
  1991年   14篇
  1990年   16篇
  1989年   9篇
  1987年   10篇
  1986年   13篇
  1985年   9篇
  1984年   13篇
  1981年   6篇
  1979年   10篇
  1977年   4篇
  1975年   7篇
  1974年   4篇
  1973年   7篇
  1972年   5篇
  1971年   6篇
  1969年   5篇
  1968年   8篇
  1967年   6篇
  1966年   4篇
排序方式: 共有1276条查询结果,搜索用时 24 毫秒
1.
This is a qualitative study of clinicians' use of partial information disclosure and its consequences for adolescents' ability to participate in the management of their cancer treatment. A total of 17 pediatric cancer patients, their families, and clinicians were observed during 15 months of ethnographic fieldwork in a hospital in Barcelona, Spain. Eighty-six hours of videotaped medical and social activities were analyzed micro-interactionally and longitudinally. Clinicians used 4 strategies to evade direct answers to adolescents' questions: contingent answers, narrow answers, non-answer responses, and question forestalling. Information withholding by clinicians was shown to greatly limit adolescents' ability to participate in the management of their treatment and to be ineffective in its implicit goals of protecting the patient and containing uncertainty and anxiety. The author concludes that if clinicians were to integrate adolescents' individual information needs into their communicative practices they would be able to better assess what information to disclose as well as how and when to disclose it.  相似文献   
2.
PURPOSE: A laboratory investigation was undertaken to assess the effects of propofol on renal function, through modulation of the systemic inflammatory response, in an in vivo experimental model of aortic surgery in comparison with sevoflurane. METHODS: Twenty young male piglets were anesthetized with either propofol 4 mg.kg(-1).hr(-1) (n = 10) or sevoflurane 1.5% end-tidal concentration (n = 10). Animals were subjected to aorta-aortic bypass with suprarenal aortic clamping for 30 min. At specific intervals (basal -before the start of surgery; reperfusion 15 min after unclamping the aorta; at 24, 48 and 72 hr after surgery, and on the seventh day after surgery) the levels of the following were determined: plasma creatinine, renal myeloperoxidase, tumour necrosis factor-alpha, interleukin 1-ss, and interferon-gamma; kidney superoxide anion and its detoxifying enzyme superoxidase dismutase, kidney malondialdehyde and the activity of inducible nitric oxide synthase. Seven days after surgery, the animals were anesthetized using the described techniques, and after blood withdrawal and kidney sampling they were sacrificed. RESULTS: In comparison with sevoflurane, propofol was associated with a lower concentration of plasma creatinine (P < 0.05) together with lower concentrations of myeloperoxidase, tumour necrosis factor-alpha, interleukin 1-ss, interferon-gamma, superoxide anion and superoxidase dismutase, malondialdehyde and inducible nitric oxide synthase (P < 0.05). CONCLUSION: In an experimental model of aortic reconstructive surgery, and compared with sevoflurane, propofol anesthesia is associated with less neutrophil infiltration, lower plasma proinflammatory cytokine levels, lower production of oxygen free radicals, less lipid peroxidation, and reduced inducible nitric oxide synthase activity. These observations suggest a possible renal protective effect of propofol in this surgical setting.  相似文献   
3.
The intensity dependence of the auditory-evoked potentials (IDAP) is inversely related to serotonergic tone. Depression is frequently observed after stroke, associated with cognitive impairment and increased mortality. Aim of this study was to investigate the serotonergic tone in acute stroke patients by IDAP. Consecutive patients with an acute stroke admitted in our stroke unit were evaluated using clinical and instrumental examinations and compared with healthy controls. The IDAP was calculated as the linear amplitude/stimulus intensity function (ASF) slope, by measuring the peak-to-peak amplitude of Nl-P2 on four blocks of different stimulus intensities. Twenty patients were enrolled; 11 had a right brain infarction; nine had depressive symptoms (DS). The ASF slope of the auditory-evoked potentials was markedly increased in stroke patients compared with controls ( P  = 0.021). Stroke patients with DS had a significant steeper ASF slope than controls ( P  = 0.017). There was no statistical difference in ASF slope between stroke patients without DS and controls. Post-stroke depression pathophysiology is still debated. Our study suggests that in acute stroke patients with DS, there is a direct involvement of the serotonergic system, regardless the degree of disability and the site of the lesion.  相似文献   
4.
Basic fibroblast growth factor (bFGF or FGF-2) is present in the basal membrane of pancreatic cells during the pancreatic embryonic development. The expression of bFGF receptors has been described in normal pancreatic cells. By contrast, pancreatic cancer cells express not only the bFGF receptors but also the bFGF itself. With the aim of understanding the effects induced by the production of bFGF by pancreatic cancer cells, the pancreatic acinar cell line (AR4-2J) was used. AR4-2J cells do not produce bFGF but express bFGF receptors. These cells were transfected with a vector containing the bFGF cDNA encoding the three different forms of bFGF characterized in tumor cells. Results showed that the bFGF expression induced important phenotypic and enzymatic modifications. The transfected cells lost some morphological features of the acinar cells and expressed amylase and lipase at low levels (a 90% decrease for amylase activity, whereas lipase activity was barely detectable). These results suggest that bFGF could be involved in maintaining pancreatic cells in a slightly differentiated state.  相似文献   
5.
Background Benign esophageal pseudoachalasia is a rare condition. Discussion We report the case of a 70-year-old man who complained of severe dysphagia after laparoscopic Nissen fundoplication and crural mesh repair performed for long-standing gastroesophageal reflux disease. Severe dysphagia and nocturnal aspiration developed soon after the operation. A marked dilatation of the esophageal body and a manometric pattern resembling achalasia was documented. Results Endoscopic balloon dilatation was ineffective. Five months after the initial operation, the patient underwent revisional laparoscopic surgery that consisted of Nissen’s wrap takedown, enlargement of the hiatus with partial resection of the mesh, Heller myotomy, and Dor fundoplication. After a 2-year follow-up, the patient is doing well and is free of symptoms.  相似文献   
6.
BACKGROUND: Equilibration of hemoglobin concentration after transfusion has been estimated to take about 24 hours, but some studies have shown that earlier measurements reflect steady-state values in persons who have not bled recently. This study was aimed at assessing the changes over time in hemoglobin concentration after transfusion in acutely anemic patients because of recent bleeding. STUDY DESIGN AND METHODS: Thirty-two normovolemic patients recovering from an acute bleeding episode who were no longer thought to be bleeding and who received a 2- unit red cell transfusion were studied. At baseline and 15, 30, 60, and 120 minutes and 24 hours after transfusion, hemoglobin concentration and hematocrit values were measured. RESULTS: The administration of 2 units of packed red cells elicited a 24-hour increase of 22.4 +/− 6.8 g per L in hemoglobin concentration. Hemoglobin values were not different at any of the defined posttransfusion times. Hematocrit levels experienced similar changes over time. Agreement between 15-minute and 24-hour values was excellent, as only 6 percent of patients exhibited a clinically significant difference (> 6 g/L) between the hemoglobin measurements. CONCLUSION: Hemoglobin and hematocrit values rapidly equilibrate after transfusion in normovolemic patients who are recovering from an acute bleeding episode. This fact would allow a rapid assessment of the effects of transfusion and of the recurrence of bleeding in patients remaining at risk.  相似文献   
7.
Five hundred six consecutive cases of ductal infiltrating carcinoma of the breast (T1-T2,N0,M0) were evaluated to define the frequency of peritumoral lymphatic invasion (PLI) and verify its possible prognostic significance. Histologically, PLI was characterized by the presence of neoplastic emboli within vascular lumina lined by recognizable endothelial cells, adjacent to but outside the margins of the carcinoma. In routine histopathologic assessment the frequency of PLI was 68% whereas in a randomly selected group of 234 reviewed cases the frequency rose to 20%. Patients with routinely evaluated PLI had a worse prognosis than those without PLI with reference both to disease-free survival (P = 0.0001) and total survival rates (P = 0.0001). The difference for local recurrences was prognostically highly significant (P = 0.0001) and also significant for the development of metastases (P = 0.0576). In the reviewed material the difference in prognosis between PLI-positive and PLI-negative cases was not confirmed for total survival whereas the significance for the disease-free interval persisted. The assessment of PLI, carried out following strict histopathologic criteria, appears to select a group of node-negative breast cancer patients who have an increased risk of recurrences and might benefit from a treatment different from that reserved for node-negative and PLI-negative patients.  相似文献   
8.
The reactions of a monoclonal antibody to the MCF7 breast cancer cell line were immunohistochemically studied on a variety of breast tumors, primary and metastatic, on mammary epithelium and on nonneoplastic breast lesions. A high proportion of positive reactions was observed in ductal, lobular, and tubular carcinomas as well as in mammary Paget's disease. Mucinous, medullary, and papillary carcinomas showed a low incidence of reactivity. Carcinomas with metaplasia, carcinoids, and nonepithelial breast tumors were unreactive with the antibody. Positive immunostaining was documented also in nodal and extranodal metastatic lesions. The staining of nodal metastases was correlated with the positive reaction of the primary tumor. Reactivity was widely distributed in normal breast epithelial cells and in benign breast lesions. Staining of nonneoplastic mammary epithelial was associated with reactivity of adjacent neoplastic tissues. Staining differences between nonneoplastic and neoplastic mammary tissues were related to the intensity and cytologic distribution of the labeling. Heterogeneous reactivity of morphologically similar cells was documented in nonneoplastic and neoplastic breast epithelial cells as well as in nodal and extranodal breast carcinoma metastases. Immunohistologically detectable antigen was not correlated with prognostic factors such as histologic grade or nodal status. A retrospective study of T1NO cases failed to substantiate any prognostic value for the reactivity of primary breast tumors with this monoclonal antibody.  相似文献   
9.
Increased HLA-DR homozygosity associated with pre-eclampsia   总被引:5,自引:0,他引:5  
It is generally accepted that maternal recognition of paternally derived fetal antigens occurs during normal pregnancy and may be beneficial for implantation and maintenance of gestation. Thus, we have investigated the human leukocyte class II DR antigens (HLA-DR), whose role in self and non-self recognition is well known, in women with pre-eclampsia, their partners and in control couples. The HLA-DR antigens were tested in 70 pre-eclamptic primigravidae women and their partners and 70 healthy control couples using the serological Terasaki technique. Our results did not show any particular HLA-DR antigen to be correlated with pre-eclampsia, but a statistically significant increase of only one identifiable HLA-DR antigen, which was presumed to express homozygosity at the HLA-DR locus, in the pre-eclamptic women and their partners: 67.1 versus 7. 9% in the control couples (P < 0.000001). The analysis of HLA-DR compatibility between pre-eclamptic women and their partners showed a statistically highly significant increase of the female-to-male compatibility (P = 0.0003) and a lower but significant male-to-female compatibility in comparison with controls (P = 0.014). From our results, it emerges that HLA-DR homozygosity and reduced antigenic disparity seem to be associated to a major risk for pre-eclampsia, which consequently appears to be a 'couple's disease'.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号