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   1496篇
  免费   71篇
  国内免费   8篇
耳鼻咽喉   26篇
儿科学   37篇
妇产科学   31篇
基础医学   144篇
口腔科学   29篇
临床医学   158篇
内科学   311篇
皮肤病学   17篇
神经病学   114篇
特种医学   101篇
外科学   292篇
综合类   15篇
预防医学   61篇
眼科学   41篇
药学   148篇
中国医学   6篇
肿瘤学   44篇
  2024年   3篇
  2023年   21篇
  2022年   71篇
  2021年   105篇
  2020年   38篇
  2019年   44篇
  2018年   63篇
  2017年   50篇
  2016年   41篇
  2015年   45篇
  2014年   68篇
  2013年   89篇
  2012年   97篇
  2011年   100篇
  2010年   61篇
  2009年   54篇
  2008年   65篇
  2007年   94篇
  2006年   115篇
  2005年   72篇
  2004年   76篇
  2003年   54篇
  2002年   72篇
  2001年   5篇
  2000年   15篇
  1999年   6篇
  1998年   11篇
  1997年   2篇
  1996年   2篇
  1995年   4篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1991年   8篇
  1990年   3篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1970年   1篇
  1969年   1篇
  1965年   1篇
  1960年   1篇
排序方式: 共有1575条查询结果,搜索用时 15 毫秒
991.
INTRODUCTION: This is a retrospective study to determine the effects of vertebroplasty and kyphoplasty on quality of life in multiple myeloma patients with spinal compression fractures. MATERIAL AND METHODS: Thirty-four patients with primary multiple myeloma were treated for symptomatic compression fractures between June 2003 and June 2005. Kyphoplasty was applied to 22 levels in 18 and vertebroplasty to 28 levels in 16 patients. The pain-related disability was evaluated for every single daily living activity using visual analog scale (VAS) over 10 points. (pain at rest, walking, sitting-standing, taking a shower and wearing clothes). (This evaluation is performed to every patient with degenerative disorders of the spine upon admission to our clinic.) Overall VAS scores were evaluated over 50 points (0 minimum, 50 maximum) preoperatively, at postoperative six weeks, six months and at one year prior to taking analgesics. The amount of analgesic use was recorded. Data was analyzed statistically using variance analysis, Friedman's multiple comparison test and Student's t test. RESULTS: The mean overall pain score in the kyphoplasty group decreased from a preoperative value of 36 to 12.13 at the sixth postoperative week, to 8.63 at the sixth month and to 9.72 at one year. (p<0.001). The mean overall pain score in the vertebroplasty group decreased from a preoperative value of 37.83 to 15.33 at the sixth postoperative week, to 12.17 at sixth months and to 13.47 at one year. (p<0.001). Student's t test was used to analyze the percentage of differences in overall pain score. Difference between groups was not statistically significant at the sixth week (p=0.106) but was statistically significant both at the sixth month (p=0.024) and at one year (p=0.027) in favor of kyphoplasty group. No secondary collapse was observed in adjacent levels in both groups. There were no intrapostoperative neurologic/pulmonary complications in both groups. Analgesics usage significantly decreased in both groups. CONCLUSION: In multiple myeloma, when pathological spinal compression fractures cause intractable pain and are unresponsive to conservative treatment, both vertebroplasty and kyphoplasty are effective in increasing quality of life and decreasing pain.  相似文献   
992.
Background: Although angiotensin-converting enzyme inhibitors (ACEIs) have been shown to prolong life in patients with congestive heart failure (CHF), the prognosis of these patients remains poor.Objective: The purpose of the study was to reevaluate a cohort of patients with CHF after 7 years of follow-up with cilazapril therapy to assess the renin-angiotensin system (RAS), anatomic and functional capacity of the heart, and aldosterone escape.Methods: Surviving patients from a cohort hospitalized for CHF between January 1994 and December 1994 who were treated with cilazapril in our center were included in this study. Exercise testing was carried out using the Kattus protocol, and breath-by-breath oxygen analysis, echocardiography, and hormonal analysis were done.Results: Seven patients (5 men, 2 women; mean [SD] age, 70.6 [4.4]) were included in the study. Compared with the early effects (at 15 days) of cilazapril therapy, only mean (SD) peak exercise time decreased significantly at the 7-year follow-up (8.9 [2.4] minutes vs 5.1 [1.9] minutes; P = 0.02). Mean (SD) anaerobic threshold (AT) oxygen consumption and AT ratio increased slightly from 15 days, although these changes were not statistically significant (12.86 [3.5] mL/kg·min vs 13.57 [2.6] mL/kg·min; 70.3% [7.7%] vs 78.9% [9.8%], respectively). Compared with the early effect of therapy, patients had slightly lower mean (SD) ejection fractions (EFs), but the decrease did not reach statistical significance (52% [4%] vs 48% [4%]). Aldosterone levels were within normal limits in all patients, and 2 patients had increased RAS activity.Conclusions: In this study, the observed lack of aldosterone escape, as well as patient survival during ACEI therapy, may be due to selection bias of the surviving patients, who had better EFs and lack of aldosterone escape. Therefore, the remaining issue seems to be the selection of patients who will not show aldosterone escape during chronic ACEI treatment.  相似文献   
993.
994.
The objective of this study was to evaluate the utility and sensitivity of routine pelvic radiographs (PXR) in the initial evaluation of blunt trauma patients. A retrospective review was performed. One hundred seventy-four patients with a pelvic fracture who had computed tomography (CT) and PXR were included (average age, 36.1; average Injury Severity Score, 16.3). Nine (5%) patients died. Five hundred twenty-one fractures were identified on CT. One hundred sixteen (22%) of these fractures were missed by PXR. Eighty-eight (51%) patients were underdiagnosed by PXR alone. The most common fractures missed by PXR were sacral and iliac fractures. Eight patients required angiograms, with four undergoing therapeutic pelvic embolization. Forty-seven (27%) patients were hypotensive or required a transfusion in the emergency department. These patients were more likely to require an angiogram (17% vs 0%, P < 0.0001) and were more likely to require embolization (9% vs 0%, P < 0.001). This study demonstrates that CT scan is highly sensitive in identifying and classifying pelvic fractures. PXR has a sensitivity of only 78 per cent for identification of pelvic fractures in the acute trauma patient. In hemodynamically stable patients who are going to undergo diagnostic CT scan, PXR is of little value. The greatest use of PXR may be as a screening tool in hemodynamically unstable patients and/or those that require transfusion to allow for early notification of the interventional radiology team.  相似文献   
995.
Oxime reactivators HI‐6, obidoxime, trimedoxime, K347 and K628 were investigated as drugs designed for treatment of tabun intoxication. The experiments were performed on rats in order to simulate real conditions. Rats were intoxicated with one LD50 of tabun and treated with atropine and mentioned reactivators. Activities of erythrocyte acetylcholinesterase (AChE), plasma butyrylcholinesterase (BChE) and brain AChE were measured as markers of reactivation efficacy. An estimation of low molecular weight antioxidant levels using cyclic voltammetry was the second examination parameter. The evaluation of cholinesterases activity showed good reactivation potency of blood AChE and plasma BChE by commercially available obidoxime and newly synthesized K347. The potency of oximes to reactivate brain AChE was lower due to the poor blood–brain barrier penetration of used compounds. Commercially available reactivator HI‐6 and newly synthesized K628 caused oxidative stress measured by cyclic voltammetry as antioxidant level. The oxidative stress provoked by HI‐6 and K628 was found to be significant on probability level P = 0.05. The others reactivators did not affect antioxidant levels. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
996.
The continuous increase in the consumption of aluminium and its alloys has led to an increase in the amount of aluminium scrap. Due to environmental protection, and to reduce the costs of manufacturing aluminum in recent years, a lot of research is devoted to recycling of aluminum alloys. The paper presents the results of research concerning the possibility of manufacturing standardized alloy 2017A from commercial and post-production scrap by continuous casting. Obtained from recycling process ingots were subjected to analysis of chemical composition and intermetallic phase composition. Based on the results of light microscopy (LM), scanning electron microscopy + electron dispersive spectroscopy (SEM + EDS), and X-ray diffraction (XRD) the following phases in the as-cast state were identified: θ-Al2Cu, β-Mg2Si, Al7Cu2Fe, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3(SiCu)2. During solution heat treatment most of the primary precipitates of intermetallic phases, like θ-Al2Cu, β-Mg2Si, and Q-Al4Cu2Mg8Si7, were dissolved in the solid solution α-Al, and during natural and artificial aging they precipitate as strengthening phases θ-Al2Cu and Q-Al4Cu2Mg8Si7 with high dispersion. The highest hardness—150.3 HB—of 2017A alloy was obtained after solution heat treatment from 510 °C and aging at 175 °C. In the static tensile test the mechanical (Rm and Rp0.2) and plastic (A5) properties were determined for 2017A alloy in the cast state and after T4 heat treatment. The highest strength properties—tensile strength Rm = 450.5 MPa and yield strength R0.2 = 268.7 MPa with good relative elongation A5 = 14.65%, were obtained after solution heat treatment at 510 °C/6 h/water quenching and natural aging at 25 °C for 70 h. The alloy manufactured from recycled scrap is characterized by relatively high mechanical properties.  相似文献   
997.
998.
Fasciola hepatica is a liver fluke that infects 2.4 million of people and causes great economical loss in animal production. To date a 100% effective vaccine has not been developed and the disease is controlled by drug therapy. Great efforts are put into development of effective vaccine against parasite what is difficult since Fasciola spp. (like other helmints) during evolutionary process has developed sophisticated and efficient methods to evade immune response. During preliminary experiments it is convenient to use cell lines which are relatively cheap and allow for reproducible comparison of results between laboratories. We stimulated BOMA (bovine monocyte/macrophage cell line) and BOMAC (bovine macrophage cell line) with native or recombinant antigens of Fasciola hepatica and assessed IFN-γ, IL-4 and TNF-α level upon stimulation. We observed diminished secretion of proinflammatory TNF-α in LPS activated BOMA cells stimulated with Excretory/Secretory products of adult fluke (Fh-ES). We also observed greater changes in gene expression in LPS activated BOMA cells than in non activated BOMA cells upon stimulation using Fh-ES. The results show possibility of using cell lines for in vitro research of bovine immune response against liver fluke, although this model still requires validation and further characterization.  相似文献   
999.
The liver fluke Fasciola hepatica infects a wide range of hosts, and has a considerable impact on the agriculture industry, mainly through infections of sheep and cattle. Further, human infection is now considered of public health importance and is hyperendemic in some regions. The fluke infection causes considerable damage to the hosts’ liver. However, the mechanisms of liver destruction have not yet been completely elucidated. In the present report we incubated a human liver cell line in the presence of either F. hepatica excretory/secretory material (FhES) or recombinant phosphoglycerate kinase (FhPGK). Dosedependent cytotoxicity in the presence of FhES was observed, indicating that FhES is capable of killing human hepatocytes, supporting a role for FhES in damaging host liver cells during infection; while treatment with a recombinant intracellular protein — FhPGK, had no impact on cell survival.  相似文献   
1000.
The potency of bispyridinium acetylcholinesterase reactivator KR-22934 in reactivating tabun-inhibited acetylcholinesterase and reducing tabun-induced lethal toxic effects was compared with the oxime K203 and commonly used oximes. Studies determining percentage of reactivation of tabun-inhibited blood and tissue acetylcholinesterase in rats showed that the reactivating efficacy of KR-22934 was slightly higher than the reactivating efficacy of K203 and roughly corresponded to the reactivating efficacy of obidoxime and trimedoxime in blood and diaphragm. On the other hand, the oxime KR-22934 was not able to reactivate tabun-inhibited acetylcholinesterase in the brain. The therapeutic efficacy of all oximes studied approximately corresponded to their reactivating efficacy. Based on the results, one can conclude that the oxime KR-22934 is not suitable for the replacement of commonly used oximes for the antidotal treatment of tabun poisoning in spite of its potency to reactivate tabun-inhibited acetylcholinesterase in the peripheral compartment (blood, diaphragm).  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