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   1960篇
  免费   72篇
  国内免费   26篇
耳鼻咽喉   54篇
儿科学   117篇
妇产科学   66篇
基础医学   149篇
口腔科学   121篇
临床医学   141篇
内科学   376篇
皮肤病学   43篇
神经病学   176篇
特种医学   51篇
外科学   451篇
综合类   27篇
预防医学   28篇
眼科学   55篇
药学   118篇
中国医学   1篇
肿瘤学   84篇
  2023年   16篇
  2022年   21篇
  2021年   38篇
  2020年   27篇
  2019年   20篇
  2018年   25篇
  2017年   27篇
  2016年   51篇
  2015年   85篇
  2014年   95篇
  2013年   108篇
  2012年   151篇
  2011年   161篇
  2010年   76篇
  2009年   66篇
  2008年   103篇
  2007年   132篇
  2006年   111篇
  2005年   157篇
  2004年   117篇
  2003年   105篇
  2002年   91篇
  2001年   42篇
  2000年   42篇
  1999年   46篇
  1998年   12篇
  1997年   16篇
  1996年   13篇
  1995年   13篇
  1994年   8篇
  1993年   11篇
  1992年   12篇
  1991年   16篇
  1990年   5篇
  1989年   7篇
  1988年   8篇
  1987年   6篇
  1986年   4篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1974年   2篇
  1972年   2篇
  1970年   1篇
  1967年   1篇
排序方式: 共有2058条查询结果,搜索用时 15 毫秒
31.
Intravenous ganciclovir is the standard treatment for cytomegalovirus disease in solid organ transplant recipients. Oral valganciclovir is a more convenient alternative. In a randomized, international trial, recipients with cytomegalovirus disease were treated with either 900 mg oral valganciclovir or 5 mg/kg i.v. ganciclovir twice daily for 21 days, followed by 900 mg daily valganciclovir for 28 days. A total of 321 patients were evaluated (valganciclovir [n = 164]; i.v. ganciclovir [n = 157]). The success rate of viremia eradication at Day 21 was 45.1% for valganciclovir and 48.4% for ganciclovir (95% CI -14.0% to +8.0%), and at Day 49; 67.1% and 70.1%, respectively (p = NS). Treatment success, as assessed by investigators, was 77.4% versus 80.3% at Day 21 and 85.4% versus 84.1% at Day 49 (p = NS). Baseline viral loads were not different between groups and decreased exponentially with similar half-lives and median time to eradication (21 vs. 19 days, p = 0.076). Side-effects and discontinuations of assigned treatment (18 of 321 patients) were comparable. Oral valganciclovir shows comparable safety and is not inferior to i.v. ganciclovir for treatment of cytomegalovirus disease in organ transplant recipients and provides a simpler treatment strategy, but care should be taken in extrapolating to organ transplant recipients not properly represented in the present study.  相似文献   
32.
The treatment of unstable trochanteric femoral fractures is still challenging, and the proximal femoral nails are becoming more commonly used. The proximal femoral nailing is usually performed on a fracture table under traction which is associated with some possible complications. In our study, we tried to present the results of proximal nailing surgery performed in the lateral decubitus position and manual traction on a radiolucent table without the fracture table traction.  相似文献   
33.
The aim of this study was to compare the effectiveness of antioxidants including cysteamine (2.5, 7.5 mm ), hyaluronan (0.25, 1 mg ml?1) and fetuin (5, 10 mg ml?1) in the freezing of Brown Swiss bull semen. The best percentages of CASA motilities were achieved with 10 mg ml?1 of fetuin and 2.5 mm of cysteamine. For sperm morphology, 10 mg ml?1 of fetuin and 2.5 mm of cysteamine had better protective effects (P < 0.001). The results of hypo‐osmotic swelling test showed that the percentage values of membrane integrity in all the groups, excluding that supplemented with 5 mg ml?1 of fetuin, were higher than those of the control group (P < 0.001). Results obtained for the DNA damage of sperm cells demonstrated that 0.25 mg ml?1 of hyaluronan, and 2.5 and 7.5 mm of cysteamine led to lower rates of spermatozoa with damaged DNA, compared with the control group (P < 0.001). The maintenance of superoxide dismutase and glutathione peroxidase antioxidant activities following freeze‐thawing with 2.5 and 7.5 mm of cysteamine and 10 mg ml?1 of fetuin was demonstrated to be at a higher level in comparison with the control group (P < 0.001). Malondialdehyde formation was found to be lower in the groups supplemented with 0.25 mg ml?1 of hyaluronan and 7.5 mm of cysteamine after the freeze‐thawing process (P < 0.001).  相似文献   
34.
35.
OBJECTIVE: To examine the effects of different suture materials and suturation techniques on cartilage reshaping in a rabbit model. METHODS: Twenty-two rabbits were used. Posterior skin flaps were elevated, and 4 cartilage struts were prepared on each auricula. Each strut was bent at its midpoint, and the skin under the bent area was elevated only in 1 side. The strut was sutured either with catgut, polyglactin 910, polydioxanone, or polypropylene sutures. Anteriorly, the suture was passed subcutaneously on 1 side, while transcutaneously on the other. Animals were killed at the first and fourth months. The shape of the struts was macroscopically evaluated. Inflammation and foreign body reaction around the suture were examined under light microscopy. RESULTS: Maintenance of shape with all suture materials was significantly lower in the transcutaneously sutured group than in the subcutaneously sutured group. Because of high rates of suture loss in the transcutaneously sutured group, further evaluations on cartilage tissue were made only in subcutaneously sutured group. Success rate in maintenance of shape was similarly high in the polydioxanone, polyglactin 910, and polypropylene suture groups; however, it was significantly lower in the catgut suture group. CONCLUSION: Long-lasting absorbable suture materials are as effective as nonabsorbable ones, and the subcutaneous technique is more effective than the transcutaneous technique.  相似文献   
36.
Although, one out of every eight women has a risk of developing breast cancer, the reported incidence of breast carcinoma detection in reduction mammaplasty materials is rather low. To our knowledge, specimen radiography, which is used for breast biopsies has not been used for the assessment of breast reduction materials. We investigated the applicability of specimen radiography and its potential benefits in detection of the breast pathologies, especially malignancies in reduction mammaplasty materials. Forty patients scheduled for reduction mammaplasty operation were included. In all cases an inferior pedicle reduction technique was preferred and the radiographs of the resected breast tissues were taken immediately. The radiographs were evaluated for any possible pathologic appearance and all abnormal findings were marked. For the histopathologic evaluation, in addition to the random sampling of the pathologist, any marked areas were also microscopically examined. In two cases fibrocystic changes were found in radiographs and the same results were obtained in the histological examination. No false negative mammogram was seen. Specimen radiography, which is applicable for breast reduction materials is an easy and cheap method and does not cause any patient discomfort. It seems that the radiographs of reduction mammaplasty materials are useful to provide guidance to the pathologist during tissue sampling for microscopic examination especially when large amounts of breast tissue is excised.  相似文献   
37.
Background. Chronic kidney disease (CKD) and hemodialysis (HD) patients who cannot restrict sodium consumption in their diets sometimes develop significant saline excess and hypertension between dialyses. This study assessed the effect of relatively low sodium dialysate dialysis on changes of echocardiography in hemodialysis patients. Methods and Results. Eighteen patients with end stage renal failure on chronic HD were studied (8 females, 10 males) with a mean age 48.3 ± 14.6 (24–70) years. The mean time on HD was 30.8 ± 14.0 (12–60) months. Patients with hematocrit levels under 24% were excluded from the study. In all patients, echocardiography was performed thrice weekly before and after eight-week HD treatment with low sodium dialysate hemodialysis by the same operator (135 mEq/L for patients with sodium levels less than 137, 137 for patients with sodium levels over 137). Left atrium (LA) and left ventricle (LV) volumes and ejection fractions were measured, specifically: LV systolic diameter (LVSD), LV diastolic diameter (LVDD), interventricular septum (IVS), tricuspid regurgitation (TR), mitral regurgitation (MR), pulmonary artery pressure (PAP), and inferior vein cava diameter (IVCD). Results. In terms of echocardiographic parameters, LVSD, TR, PAP, and IVCD were statistically decreased after low-sodium dialysate treatments (p?=?0.002, 0.04, 0.013, and 0.00, respectively). Predialysis systolic and diastolic blood pressure (BP), post-dialysis systolic blood pressure, and interdialytic weight gain was statistically decreased when compared to basal levels (p?=?0.00, p?=?0.011, p?=?0.022, p?=?0.001, respectively). Conclusion A reduction of the dialysate sodium concentration based on the predialysis sodium levels of the patients could reduce the systolic BP and decrease the volume load on the heart as assessed by echocardiography. Within this short period, postdialysis diastolic BP could not be lowered. The effect of this approach should be studied in broad and lengthy series.  相似文献   
38.

Objectives

The influence of dentin adhesive systems (Scotchbond Multi-Purpose, XP Bond, Xeno V, Clearfil Protect Bond, AdheSE) on cell survival, viability and proliferation was characterized after direct and indirect exposure using different cell culture techniques.

Materials and methods

The primers and cured bonding parts were directly exposed to cells using cell culture inserts, and complete materials were analyzed in a dentin barrier test. Cell responses were examined in 3T3 mouse fibroblasts after 24- and 72-h exposure periods by the estimation of total cell numbers (survival), apoptosis (viability) and cell proliferation.

Results

Cell numbers were effectively reduced by the primers of AdheSE, Protect Bond, and Scotchbond Multi-Purpose as well as XP bond after direct exposure in a cell culture insert test device. Likewise, Scotchbond Multi-Purpose primer induced a rate of apoptosis (93.9%) even higher than detected with Protect Bond primer (91.6%). Cell proliferation was entirely inhibited by primers and by Xp Bond as well. The Scotchbond Multi-Purpose was most cytotoxic in a dentin barrier test device after a 24-h indirect exposure. It also increased the percentage of cells in apoptosis to 15.4% compared to untreated controls.

Conclusion

Unpolymerized primers of dentin adhesives were more cytotoxic than polymerized bonding counterparts. Moreover, total etch dentin adhesives were more cytotoxic than self-etch adhesives.

Clinical relevance

When dentin adhesives are used in deep cavities without a protective dentin barrier the leachable hydrophobic and hydrophilic component of dentin adhesive systems can penetrate to the pulp and may induce cytotoxic responses in pulp tissues.  相似文献   
39.
40.
Objectives:It is suggested that excessive calcium entry into neurons is the main triggering event in the initiation of epileptic discharges. We aimed to investigate the role of T and N type calcium channels in absence epilepsy experimental model.Results:Beta and delta recording ratios in 1 μM/5 μl mibefradil group was significantly different from basal and other dose-injected groups. Beta, alpha, and theta recordings in 0.2 μM/5 μl w-Conotoxin MVIIA group was significantly different from basal and other dose-injected groups. In w-Conotoxin MVIIA after mibefradil group, beta, alpha, and theta recording ratios were significantly different from basal and mibefradil group. Mibefradil and w-Conotoxin MVIIA significantly decreased the frequency and duration of SWDs. The decrease of frequency and duration of SWDs in mibefradil group was significantly different from w-Conotoxin MVIIA group. The frequency and duration of SWDs significantly decreased in w-Conotoxin MVIIA after mibefradil group compared with basal, mibefradil, and w-Conotoxin MVIIA groups.Conclusions:We concluded that both T and L type calcium channels play activator roles in SWDs and have positive effects on frequency and duration of these discharges. These results are related with their central effects more than peripheral effects.KEY WORDS: Epilepsy, mibefradil, T and N type calcium channels, Wistar Albino Glaxo/Rij rats, w-Conotoxin MVIIA  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