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   58209篇
  免费   4030篇
  国内免费   500篇
耳鼻咽喉   989篇
儿科学   896篇
妇产科学   1050篇
基础医学   9254篇
口腔科学   1773篇
临床医学   5679篇
内科学   11311篇
皮肤病学   2008篇
神经病学   4706篇
特种医学   3121篇
外科学   6919篇
综合类   286篇
现状与发展   3篇
一般理论   24篇
预防医学   3244篇
眼科学   1047篇
药学   5317篇
中国医学   722篇
肿瘤学   4390篇
  2023年   391篇
  2022年   1289篇
  2021年   2133篇
  2020年   1135篇
  2019年   1662篇
  2018年   2057篇
  2017年   1620篇
  2016年   2175篇
  2015年   2903篇
  2014年   3127篇
  2013年   3814篇
  2012年   5602篇
  2011年   5320篇
  2010年   3034篇
  2009年   2399篇
  2008年   3612篇
  2007年   3340篇
  2006年   2991篇
  2005年   2784篇
  2004年   2315篇
  2003年   2059篇
  2002年   1789篇
  2001年   614篇
  2000年   553篇
  1999年   471篇
  1998年   274篇
  1997年   230篇
  1996年   197篇
  1995年   142篇
  1994年   132篇
  1993年   120篇
  1992年   176篇
  1991年   190篇
  1990年   166篇
  1989年   141篇
  1988年   129篇
  1987年   121篇
  1986年   130篇
  1985年   99篇
  1984年   105篇
  1983年   69篇
  1982年   67篇
  1981年   73篇
  1980年   55篇
  1979年   77篇
  1978年   54篇
  1975年   67篇
  1972年   52篇
  1971年   60篇
  1970年   47篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
Immunosuppressive therapy (IST) has provided an alternative treatment option for cure of aplastic anemia patients who cannot receive bone marrow transplantation. Although there have been many recent studies on the efficacy of antithymoglobulin (ATG) combined with cyclosporine A (CsA), there is no data on the correlation between the variability of CsA levels and the response to IST. Therefore, we retrospectively assessed the factors associated with IST efficacy in patients with acquired severe aplastic anemia (SAA). Sixty‐six patients were treated with ATG combined with CsA for 6 months. In the response group, the CsA levels were increased rapidly to more than 200 ng/mL within the first 2 wk after starting the IST. However, the non‐response group had a pattern of slower increase of the CsA levels. The CsA levels, during the first and second week of treatment with IST, were significantly different in the responders and non‐responders. The factors predictive of response to IST and survival were analyzed. The univariate analysis showed that a younger age at the initiation of IST, a high absolute neutrophil count prior to starting IST, a short interval between the diagnosis and initiation of IST, and high CsA levels during the first and second week of IST treatment were positively associated with the response rate and overall survival. The multivariate analysis showed that these four factors were independent factors associated with a longer patient survival. A high response rate was associated with a short interval between diagnosis and initiation of IST as well as high CsA levels during the first and second week of IST. Therefore, early intensification of CsA levels might improve patient outcome.  相似文献   
972.
Nitric oxide (NO) is an important biomolecule for regulating various brain functions, such as the control of neurovascular tone. NO, however, cannot be stored inside cells where NO is produced and immediately diffuses through the cellular membrane and decays rapidly, which makes the detection of NO extremely hard in an in vivo setting. We constructed an amperometric NO nanosensor and utilized it to directly measure NO release in the living brain. The NO nanosensor uses nanopores (pores with an opening radii <500 nm) in which NO is oxidized at the porous platinum surface. The nanopore-based sensor was inserted vertically into the brains of anesthetized mice up to the end of the hippocampal CA 3 region, or to a depth of about 3 mm. The sensor was slowly advanced in the brain in 0.5 μm increments and in 0.05 s temporal steps. Different levels of NO release were monitored by the nanopore NO sensor during the course of the penetration. The hippocampal CA3 region had the highest level of NO release, which was followed by CA2 and CA1 of the hippocampus and the cortex. The levels of NO release were not uniformly distributed within the cortical and hippocampal areas of living brain. In sum, the nanopore-based NO sensor was able to grossly measure NO contents within living brain in real time and with high sensitivity. This study may provide good insights about the relationship between the distributions of NOS-immunoreactive neurons and the directly measured levels of NO release in brain.  相似文献   
973.
974.
975.

Background

Hepatic osteodystrophy has been reported in patients with various chronic liver diseases, including liver cirrhosis. However, it has not been well investigated in patients with hepatitis B virus infection. The aim of this study was to investigate the association between hepatitis B surface antigen (HBsAg) seropositivity and bone mineral density (BMD) in a population representative of normal Koreans.

Methods

Subjects with both HBsAg and BMD levels examined during the 2008–2010 Korea National Health and Nutrition Examination Surveys were included. HBsAg-seropositive (+) subjects were compared with those who were HBsAg-seronegative (?). BMD was measured at the lumbar spine and femur by dual-energy X-ray absorptiometry. Multivariable logistic regression was performed for BMD.

Results

In total, 11,306 participants were included in this study, among which 423 (3.7 %) were HBsAg(+): 153 premenopausal female (3.4 %), 83 postmenopausal female (3.5 %), and 187 male (4.2 %). Multivariable logistic regression analysis adjusted for age and body mass index showed that HBsAg(+) male had significantly lower BMD of the femoral neck than HBsAg(?) male (0.810 ± 0.009 vs. 0.827 ± 0.002 g/cm2, p = 0.035). Further adjustment for waist circumference, smoking, drinking, exercise, income, occupation, and vitamin D levels showed that HBsAg(+) male had significantly lower BMD of the femur neck (0.810 ± 0.010 vs. 0.831 ± 0.002 g/cm2, p = 0.032) and lumbar spine (0.953 ± 0.011 vs. 0.974 ± 0.003 g/cm2, p = 0.049) than HBsAg(?) male.

Conclusions

HBsAg seropositivity was significantly associated with lower BMD in male. Future long-term prospective studies investigating bone turnover markers and hormones are needed to better understand the pathophysiology and clinical significance of chronic hepatitis B virus-related hepatic osteodystrophy.
  相似文献   
976.
BACKGROUND: Fragmented QRS (FQRS) complexes, not typical of a bundle branch block, are a marker of regional myocardial injury. The extent of stress myocardial perfusion imaging (MPI) abnormalities with FQRS patterns is not known. METHODS AND RESULTS: Twelve-lead electrocardiograms (ECGs) in 501 patients undergoing stress MPI were studied. FQRS was defined as a QRS duration of 120 milliseconds or less, with notches or slurs of QRS complexes, on 2 contiguous leads of a coronary artery territory. Abnormal MPI was defined as a regional summed stress score (SSS) and summed rest score (SRS) of 3 or greater based on a 17-segment model. Patients with a typical bundle (n = 26), paced rhythm (n = 2), and Q waves (n = 64) were excluded. Of the remaining 409 patients (mean age, 58 +/- 13 years; 52% male), 155 (38%) had FQRS on the ECG. FQRS patients had a higher mean SSS, SRS, and global summed difference score and a lower left ventricular ejection fraction (all P < .001), as well as greater regional stress MPI scar (69% vs 11%, P < .001). FQRS pattern sensitivity was 75% and specificity was 94% for a corresponding regional MPI scar. On logistic regression, SSS, SRS, summed difference score, left ventricular ejection fraction, and regional scar were univariate predictors of the FQRS pattern on the ECG (all P < .01), and any regional scar (odds ratio, 32; P < .001) was a multivariate predictor. CONCLUSIONS: FQRS complexes on an ECG are a marker of higher stress MPI perfusion and functional abnormalities. Regional FQRS patterns denote the presence of a greater corresponding focal regional myocardial scar on stress MPI.  相似文献   
977.
978.
979.
BACKGROUND/AIMS: Antibiotic resistance and poor compliance are the main causes of Helicobacter pylori (H. pylori) eradication failure. This study evaluated the eradication rate, tolerability, and compliance of levofloxacin- azithromycin combined triple therapy for H. pylori eradication. METHODS: 1) First-line eradication: A total of 78 H. pylori-positive patients were enrolled. Seventeen military men in Armed Forces Capital Hospital were treated with 7 days of levofloxacin-azithromycin combined triple therapy (omeprazole 20 mg bid, levofloxacin 500 mg od, and azithromycin 500 mg od), and 61 patients in Kangbuk Samsung Hospital were treated with standard PPI-based triple therapy (omeprazole 20 mg bid, amoxicillin 1.0 g bid, and clarithromycin 500 mg bid) for 7 days. 2) Second-line eradication: A consecutive series of 59 patients who failed H. pylori eradication with standard PPI-based triple therapy in Kangbuk Samsung Hospital were randomized to two groups. Thirty patients were retreated with 7 days of bismuth-based quadruple therapy (omeprazole 20 mg bid, bismuth 120 mg qid, metronidazole 500 mg tid, and tetracycline 500 mg qid), and remaining 29 patients were retreated with levofloxacin-azithromycin combined triple therapy. Patient's compliance and tolerability were evaluated at the end of treatment. The status of H. pylori infection was assessed 8 weeks later then. The successful eradication of H. pylori was defined as negative results from histology and CLO test, or 13C-urea breath test. RESULTS: First-line eradication rate of levofloxacin-azithromycin triple therapy was lower than that of standard PPI-based triple therapy, but there was no statistically significant difference (70.6% vs. 80.3%, p=0.390). Second-line eradication rate of levofloxacin-azithromycin combined triple therapy was significantly lower than that of bismuth-based quadruple therapy (ITT/PP 65.5%/73.1% vs. 90%/90%, p<0.0001). The compliances of all patients were more than 85%. Two of patients with levofloxacin-azithromycin combined triple therapy complained self-limiting side effects (mild dizziness; mild insomnia with general weakness). CONCLUSIONS: Levofloxacin-azithromycin combined triple therapy should not be recommended as the first-line or second-line H. pylori eradication regimen in Korea.  相似文献   
980.
Resistin is a protein secreted from adipose tissue that is thought to play a role in insulin sensitivity. We examined the effects of rosiglitazone and metformin on the plasma resistin levels in individuals with type 2 diabetes mellitus. Patients with type 2 diabetes mellitus who showed poor glycemic control with glimepiride (4 mg/d) were randomized to rosiglitazone (4 mg/d) and metformin (500 mg bid) treatment groups. All subjects continued glimepiride treatment as well. The plasma concentrations of resistin were measured at baseline and at 6 months of treatment for both groups. The anthropometric parameters, fasting plasma glucose, HbA1c, total cholesterol, triglyceride, high-density lipoprotein cholesterol, free fatty acids, and adiponectin concentrations were also measured. After 6 months of treatment, the reduction in plasma glucose levels was similar between the 2 groups. There were no significant changes in the lipid profiles of either group during the study period. The plasma resistin levels decreased in the rosiglitazone group (2.49 +/- 1.93 vs 1.95 +/- 1.59 ng/ml; P < .05) but increased in the metformin group (2.61 +/- 1.69 vs 5.13 +/- 2.81 ng/ml; P < .05). The plasma adiponectin concentrations were increased in the rosiglitazone group (2.91 +/- 1.46 vs 4.23 +/- 1.77 microg/ml; P < .05) but were unchanged in the metformin group. In summary, rosiglitazone treatment decreased the plasma resistin levels whereas metformin treatment increased them in patients with type 2 diabetes mellitus showing poor glycemic control with sulfonylurea therapy. These results suggest that the observed changes in plasma resistin levels are not the consequences of improved insulin resistance, nor are they consequences of glycemic control. Considering the potential role of resistin in insulin resistance, decrease in resistin levels may contribute to improving insulin action with rosiglitazone treatment.  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