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   1966篇
  免费   104篇
  国内免费   30篇
耳鼻咽喉   7篇
儿科学   96篇
妇产科学   18篇
基础医学   220篇
口腔科学   29篇
临床医学   181篇
内科学   507篇
皮肤病学   36篇
神经病学   176篇
特种医学   198篇
外科学   209篇
综合类   17篇
预防医学   78篇
眼科学   12篇
药学   100篇
中国医学   2篇
肿瘤学   214篇
  2022年   14篇
  2021年   40篇
  2020年   18篇
  2019年   20篇
  2018年   34篇
  2017年   32篇
  2016年   27篇
  2015年   38篇
  2014年   63篇
  2013年   60篇
  2012年   72篇
  2011年   88篇
  2010年   83篇
  2009年   78篇
  2008年   74篇
  2007年   82篇
  2006年   83篇
  2005年   91篇
  2004年   89篇
  2003年   57篇
  2002年   61篇
  2001年   59篇
  2000年   66篇
  1999年   58篇
  1998年   50篇
  1997年   45篇
  1996年   44篇
  1995年   43篇
  1994年   18篇
  1993年   25篇
  1992年   43篇
  1991年   34篇
  1990年   36篇
  1989年   42篇
  1988年   45篇
  1987年   42篇
  1986年   28篇
  1985年   28篇
  1984年   18篇
  1983年   11篇
  1982年   18篇
  1981年   11篇
  1980年   16篇
  1979年   13篇
  1978年   10篇
  1977年   9篇
  1976年   12篇
  1975年   12篇
  1972年   8篇
  1970年   7篇
排序方式: 共有2100条查询结果,搜索用时 15 毫秒
1.
2.
用混合粘合剂碳糊电极测定丁螺环酮   总被引:6,自引:1,他引:5  
用混合粘合剂碳糊电极测定丁螺环酮张正奇,曾鸽鸣,刘传桂,黎艳飞(湖南大学化学化工系,长沙410082)碳糊电极无毒,制作方便,表面更新容易,应用电位范围广,在药物分析中已有应用[1~5]。我们在液体石腊中加入添加剂,组成混合粘合剂,可显著改善电极的检...  相似文献   
3.
4.
Blink reflex abnormalities in children with Tourette syndrome   总被引:1,自引:0,他引:1  
Tourette syndrome (TS) is a common disorder which typically occurs during childhood or early adolescence. There is no definitive diagnostic test for TS. The objective of this study was to demonstrate whether neurophysiological abnormalities of the blink reflex can be observed in children with TS. We enrolled 15 children with TS, diagnosed according to DSM IV Diagnostic Criteria, and 15 controls. The blink reflex was elicited by stimulating the supraorbital nerve in order to measure the early response (R1), homolateral and contralateral R2 (late) responses, amplitude of R1 and duration of R2. The mean duration of R2 was significantly longer in TS patients than in the controls ( P  < 0.001, Student's t -test). An abnormal pattern of the blink reflex can be, even in childhood, an early neurophysiologic marker of TS, which is not related to the duration of TS or to the age of onset.  相似文献   
5.
BACKGROUND: Sodium removal (NaR) may have a major impact on the survival of peritoneal dialysis patients. The dialysate/plasma sodium concentration ratio (D/P(Na)) is an indirect index of transcellular water transport by aquaporin channels, and thus of ultrafiltration. Sodium concentration can be assessed by means of flame photometry (F), and direct (D-ISE) or indirect ion-selective electrodes (I-ISE), but these methods have different properties. I-ISE is being used increasingly in clinical laboratories. The aim of this study was to evaluate NaR and D/P(Na) using the three different measurement methods. METHODS: We performed peritoneal equilibration tests (PETs) in 44 peritoneal dialysis patients and calculated the NaR. We also calculated D/P(Na) during the test; plasma and dialysate sodium concentrations were measured by F, D-ISE and I-ISE. RESULTS: NaR was lower (P<0.001) with D-ISE (69+/-29 mmol) than with F (81+/-29 mmol) or I-ISE (79+/-28 mmol). D/P(Na) was also lower at baseline (0.92+/-0.02 vs 0.95+/-0.02 and 0.95+/-0.02; P<0.001), after 60 min (0.87+/-0.03 vs 0.90+/-0.03 and 0.90+/-0.03; P<0.001) and at the end of PET (0.88+/-0.04 vs 0.92+/-0.04 and 0.92+/-0.04; P<0.001) when measured by D-ISE in comparison with F and I-ISE, respectively. CONCLUSIONS: NaR and D/P(Na) were lower when measured by the D-ISE method compared with the F and I-ISE methods. NaR and D/P(Na) were similar when measured by F or I-ISE. I-ISE can be used reliably in the evaluation of NaR and D/P(Na) in everyday clinical practice of peritoneal dialysis.  相似文献   
6.
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   
7.
Y Niv  C Turani  E Kahan  GM Fraser 《Gastroenterology》1997,112(6):2104-2107
Polycystic kidney disease is an autosomal dominant disease that may be associated with cystic disease of the liver. In women, the cysts may develop early and be more troublesome than in men. Cystadenocarcinoma of the pancreas is uncommon, comprising 1% of primary pancreatic malignancies. This case report is the first to describe a familial association between polycystic kidney disease and cystadenocarcinoma of the pancreas and liver in the English medical literature. A patient with autosomal dominant polycystic kidney disease (ADPKD) and multiple hepatic cysts developed cystadenocarcinoma of the pancreas with multiple malignant liver cysts. The patient's mother, sister, and niece had ADPKD, and the patient's sister also died of pancreatic cystadenocarcinoma. We believe that the development of these two disease entities in which the primary pathology is cyst formation has a genetic association. (Gastroenterology 1997 Jun;112(6):2104-7)  相似文献   
8.
We have developed an electrical method to study endothelial cell shape changes in real time in order to examine the mechanisms of alterations in the endothelial barrier function. Endothelial shape changes were quantified by using a monolayer of endothelial cells grown on a small (10(-3) cm2) evaporated gold electrode and measuring the changes in electrical impedance. Bovine pulmonary microvessel endothelial cells and bovine pulmonary artery endothelial cells were used to study the effects of alpha-thrombin on cell-shape dynamics by the impedance measurement. alpha-Thrombin produced a dose-dependent decrease in impedance that occurred within 0.5 min in both cell types, indicative of retraction of endothelial cells and widening of interendothelial junctions because of "rounding up" of the cells. The alpha-thrombin-induced decrease in impedance persisted for approximately 2 hr, after which the value recovered to basal levels. Pretreatment of endothelial cells with the protein kinase C inhibitor, calphostin C, or with 8-bromoadenosine 3',5'-cyclic monophosphate prevented the decreased impedance, suggesting that the endothelial cell change is modulated by activation of second-messenger pathways. The alpha-thrombin-induced decrease in impedance was in agreement with the previously observed increases in transendothelial albumin permeability and evidence of formation of intercellular gaps after alpha-thrombin challenge. The impedance measurement may be a valuable in vitro method for the assessment of mechanisms of decreased endothelial barrier function occurring with inflammatory mediators. Since the rapidly occurring changes in endothelial cell shape in response to mediators such as thrombin are mediated activation of second-messenger pathways, the ability to monitor endothelial cell dynamics in real time may provide insights into the signal-transduction events mediating the increased endothelial permeability.  相似文献   
9.
10.
The diagnosis of orbital rhabdomyosarcoma (RMS) in childhood gives rise to several clinical and anatomo-pathological problems. Antibodies recognizing structural proteins and cytoskeletal components have been shown to increase the diagnostic accuracy of different neoplastic lesions. In this study we examined anatomo-clinically and, where possible, by means of immunohistochemistry and electron microscopy, a series of 14 cases of orbital RMS in childhood. In the 12 cases studied by immunohistochemistry, desmin was always present, although showing variable patterns, and alpha-sarcomeric actin was found in 10 cases. alpha-Smooth muscle actin was always absent. The other markers tested (myoglobin, polyclonal actin, vimentin and enolase) proved unreliable for several reasons. We conclude that antibodies against desmin and alpha-sarcomeric actin are useful for the diagnostic definition of RMS. In addition, immunohistochemical analysis supplies data regarding the degree of tumor differentiation and may be applied to monitor radio- and chemotherapy.  相似文献   
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