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   498篇
  免费   20篇
  国内免费   32篇
耳鼻咽喉   10篇
儿科学   24篇
妇产科学   8篇
基础医学   41篇
口腔科学   24篇
临床医学   39篇
内科学   172篇
皮肤病学   3篇
神经病学   13篇
特种医学   5篇
外科学   82篇
综合类   13篇
预防医学   26篇
眼科学   41篇
药学   20篇
中国医学   3篇
肿瘤学   26篇
  2024年   1篇
  2023年   4篇
  2022年   8篇
  2021年   6篇
  2020年   9篇
  2019年   9篇
  2018年   15篇
  2017年   12篇
  2016年   17篇
  2015年   14篇
  2014年   16篇
  2013年   26篇
  2012年   38篇
  2011年   45篇
  2010年   28篇
  2009年   25篇
  2008年   39篇
  2007年   44篇
  2006年   40篇
  2005年   33篇
  2004年   20篇
  2003年   19篇
  2002年   15篇
  2001年   11篇
  2000年   14篇
  1999年   8篇
  1998年   3篇
  1997年   5篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   5篇
  1989年   1篇
  1987年   3篇
  1986年   2篇
  1967年   1篇
  1956年   2篇
  1940年   1篇
排序方式: 共有550条查询结果,搜索用时 15 毫秒
21.
22.

Background  

The recurrence of hepatitis C virus (HCV) after liver transplantation (OLT) leads to recurrent cirrhosis in up to 40% of patients.  相似文献   
23.
PURPOSE: To compare the rates of lens epithelial cell (LEC) migration and posterior capsule opacification (PCO) 1 and 3 years after sutureless small incision phacoemulsification and in-the-bag implantation of 2 acrylic polymer intraocular lenses (IOLs)-the AcrySof and MemoryLens-in fellow eyes of patients. SETTING: Eye Clinic, Beyo?lu Education and Research Hospital, Istanbul, Turkey. METHODS: Fifty patients with no systemic or ocular problems that would interfere with postoperative visual acuity were included in this prospective study. Each patient had in-the-bag implantation of an AcrySof IOL in 1 eye and a MemoryLens in the fellow eye in a randomized fashion after uneventful phacoemulsification through a sutureless clear corneal incision. RESULTS: At 1 year (n = 32 patients), there was no significant difference between fellow eyes in postoperative best corrected visual acuity (BCVA) and contrast sensitivity. In the MemoryLens group, 10 eyes (31.3%) had PCO and 9 (28.1%), LEC migration. In the AcrySof group, no eye had PCO and 2 eyes (6.3%) had LEC migration (P <.001). At 3 years (n = 21 patients), 1 eye (4.7%) in the AcrySof group had PCO and 3 eyes (14.4%) had LEC migration without PCO. In the MemoryLens group, 1 eye (4.7%) had a clear posterior capsule, 11 eyes (52.4%) had LEC migration, and 9 eyes (42.9%) had PCO (P <.001). A neodymium:YAG capsulotomy was required in 4 eyes (19.0%) in the MemoryLens group but no eye in the AcrySof group. At 3 years, BCVA was lower in the MemoryLens group than in the AcrySof group (P <.05). CONCLUSION: The 3 year clinical data of fellow eyes indicate that the AcrySof IOL causes less PCO than the MemoryLens.  相似文献   
24.
BACKGROUND: Reduced salivary flow has been reported in patients undergoing hemodialysis (HD) treatment. Our aim was to investigate the most important factors associated with stimulated salivary flow rate (ssfr) in chronic HD patients. METHODS: Fifty HD patients (27 F, 23 M, mean age 46. 7 +/- 13.2 years) were divided into two groups according to the duration of HD treatment as those receiving HD therapy less than or equal to (group I) or those more than (group II) 24 months. Fasting blood samples were obtained to determine hepatitis B and C serology, and biochemical and hematological parameters before a HD session. After prestimulation with a standard weight paraffin wax, stimulated saliva was collected in the HD patients and control group (23 F, 25 M, mean age 45.7 +/- 19.1 years) and the flow rate was expressed as ml/min. RESULTS: Both HD groups consisted of 25 patients. There was no significant difference between the two HD groups other than serum alkaline phosphatase (ALP) levels and presence of HCV. The ssfr was decreased than controls in both groups (0.8 +/- 0.6 and 0.7 +/- 0.4, respectively, vs. 1.5 +/- 0.5 ml/min) and it did not correlate with any parameter. Smoking had a positive effect on ssfr in all groups. CONCLUSION: Although the salivary flow rate decreased significantly in chronic HD patients, the duration of therapy displayed no effect on the salivary changes in HD patients, but smoking increased ssfr.  相似文献   
25.
Sex difference in verbal ability was reconsidered in relation to body size. The perceptual-verbal ability (PVA) was assessed using the A's Test. For the raw data, women excelled men, as expected. PVA positively correlated with height and weight of the subjects, but only for women. As a covariate of height, sex difference increased by increasing the women's score; men's score did not change. Tall women had much higher scores than short men. It was concluded that sex difference in PVA is stable despite the smaller body size of females than males, and body height may be predictive for this ability, but only in women.  相似文献   
26.
This explorative study was designed to identify the usage of body mechanics in clinical settings and the occurrence of low back pain in nurses. The sample was composed of 56 nurses who work on the medical, surgical, emergency and intensive care units of a state hospital in Bolu, Turkey. Data collected through observation and interviews were evaluated using percentages, Chi-square and Mann-Whitney U tests. Results of the study showed that the majority of the nurses (87.5%) experienced low back pain at some time in their lives. Among the contributing factors for back pain, the relationship between wearing high heels, heavy lifting and back pain was significant statistically. According to the observations, the majority of the nurses used body mechanics correctly while sitting (53.6%), standing (58.7%), carrying (64.3%), pulling or pushing (79.4%), moving the patient to the side of the bed without an assistant (53.4%), moving the patient to a sitting position in bed (71.4%) and assisting the patient to a standing position (66.6%). However 57.1% of the nurses lifted and 82% extended incorrectly. The conclusion from this research was that some of the nurses do not use body mechanics correctly and the majority have low back pain.  相似文献   
27.
OBJECTIVE: The purpose of this study is to test the association between joint hypermobility syndrome (JHS) and panic disorder (PD) and to determine whether mitral valve prolapse (MVP) modifies or accounts in part for the association. METHOD: A total of 115 subjects are included in this study in three groups. Group I (n = 42): panic disorder patients with MVP. Group II (n = 35): panic disorder patients without mitral valve prolapse. Group III (n = 38): control subjects who had mitral valve prolapse without any psychiatric illness. Beighton criteria were used to assess joint hypermobility syndrome. Two-dimensional and M-mode echocardiography was performed on each subject to detect mitral valve prolapse. RESULTS: Joint hypermobility syndrome was found in 59.5% of panic disorder patients with mitral valve prolapse, in 42.9% of patients without mitral valve prolapse and in 52.6% of control subjects. Beighton scores was 4.93 +/- 2.97 in group I, 4.09 +/- 2.33 in group II, and 4.08 +/- 2.34 in group III. There was no significant difference between groups according to Beighton scores. CONCLUSION: We did not detect a statistically significant relationship between panic disorder and joint hypermobility syndrome. Mitral valve prolapse and joint hypermobility syndrome are known to be etiologically related and we suggest that mitral valve prolapse affects the prevalence of joint hypermobility syndrome in the panic disorder patients.  相似文献   
28.
BACKGROUND: To analyze the trends in legally induced abortions among women younger than 30 years in the five Nordic countries, Denmark, Finland, Iceland, Norway and Sweden, since the liberalized abortion laws came into force. METHODS: Data stem from national registrations of vital events. Some have been published in the national vital statistics while others have been retrieved for this study. General and age-specific abortion rates are used to analyze the trends. Further, an index has been calculated by dividing the age-specific abortion rates by the Nordic average. RESULTS: The analysis reveals an overall reduction in the general abortion rates in the Nordic countries, apart from Iceland. The rates have been highest in Denmark and Sweden and lowest in Finland since the early 1980s. In the mid-1980s, the abortion rates increased among 15-19-year-old women in Sweden and among 20-24-year-old women in Denmark, Norway and Sweden, followed by a reduction. In Iceland the very low age-specific abortion rates for all age groups under 30 years at the beginning of the study period increased and Iceland had the highest rate for 15-19-year-old women in the late-1990s. CONCLUSIONS: The relatively low abortion rates in Finland demonstrate effective preventive efforts, although the recent increase challenges further studies on the relationship between abortion rates and counseling activities. The rise in abortion rates in Iceland indicate a need for improved sex education, contraceptive services and availability of contraceptive methods for young people.  相似文献   
29.
Recent studies documented that estrogen have antioxidant properties in-vitro, there are conflicting results on the effect of estrogen in vivo. We aimed to investigate the effects of estradiol and Raloxifene on the antioxidant enzyme [superoxide dismutase (SOD) and catalase (CAT)] activities and MDA levels in brain and liver homogenates of ovariectomized female rats. Twelve weeks after ovariectomy, female Sprague-Dawley rats (n = 26) were divided into three groups: (1) Ovariectomized placebo group (n = 6) was given physiologic saline. (2) Estrogen group (n = 10) was given Ethynyl estradiol, 0.1 mg/kg sc. (3) Raloxifene group (n = 10) was given raloxifene, 1 mg/kg sc during 8 weeks. Ten rats were used as naive controls without any treatment (Sham operated group, n = 10). Ovariectomy lead to an increase in the CAT activities in liver tissue samples compared to the sham group (p = 0.056, Mann-Whitney test). While estrogen treatment reversed to normal levels of CAT activities, raloxifene remained as ineffective. Superoxide dismutase activities and MDA levels in liver were remained unchanged in all groups. There was no significant change in the brain tissue SOD and CAT activities between the control ovariectomy, estrogen treated, and raloxifen treated groups. We determined an increase in MDA levels in brain of ovariectmised rat (p = 0.02). While raloxifene treatment reversed to normal levels of MDA (p = estrogen treatment failed. Our data showed that estrogen may play a role in regulation of CAT and SOD activities in liver due to its antioxidative effects. We can suggest estrogen and raloxifene exert their antioxidative effects in brain rather than liver. Since Raloxifene's effect is more clear than estradiol, raloxifene may be suggested primarily for treatment and/or prevention of diseases which can be resulted from oxidative stress in postmenopausal women.  相似文献   
30.
To explore whether microangiopathy is associated with disturbed glucose tolerance and peripheral neuropathy, we assessed endoneurial capillary morphology in sural nerve biopsies from men with diabetes, impaired glucose tolerance (IGT), and normal glucose tolerance (NGT). Baseline morphology was related to glucose tolerance and neuropathy at baseline and at follow-up 6 years later. Capillary density (in number per millimeters squared) at baseline was higher in subjects with diabetes (n = 10) compared with those with NGT (n = 5) at follow-up (median [interquartile range]) (86.0 [24.3] vs. 54.9 [17.1]; P = 0.0200) and in those progressing from IGT to diabetes (n = 4) compared with those with persistent IGT (n = 4) (86.7 [25.2] vs. 54.1 [14.6]; P = 0.0433). The capillary luminal area (in micrometers squared) was lower in subjects with NGT progressing to IGT (n = 2) or subjects with IGT progressing to diabetes (n = 3) compared with subjects with constant NGT (n = 6) or constant IGT (n = 4) (11.9 [2.4] vs. 20.8 [7.8]; P = 0.0201). The capillary basement membrane area (in micrometers squared) was increased in patients with peripheral neuropathy (n = 10) compared with those without (n = 7) (114.6 [68.8] vs. 75.3 [28.7]; P = 0.0084). In conclusion, increased capillary density was associated with current or future diabetes, decreased capillary luminal area with future deterioration in glucose tolerance, and increased basement membrane area with peripheral neuropathy.  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