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   4097篇
  免费   295篇
  国内免费   43篇
耳鼻咽喉   26篇
儿科学   107篇
妇产科学   93篇
基础医学   604篇
口腔科学   38篇
临床医学   315篇
内科学   1142篇
皮肤病学   292篇
神经病学   530篇
特种医学   76篇
外科学   296篇
综合类   4篇
预防医学   217篇
眼科学   31篇
药学   250篇
中国医学   6篇
肿瘤学   408篇
  2024年   12篇
  2023年   55篇
  2022年   97篇
  2021年   178篇
  2020年   121篇
  2019年   132篇
  2018年   135篇
  2017年   116篇
  2016年   140篇
  2015年   170篇
  2014年   215篇
  2013年   243篇
  2012年   337篇
  2011年   332篇
  2010年   158篇
  2009年   185篇
  2008年   255篇
  2007年   255篇
  2006年   231篇
  2005年   220篇
  2004年   198篇
  2003年   197篇
  2002年   157篇
  2001年   33篇
  2000年   24篇
  1999年   27篇
  1998年   38篇
  1997年   17篇
  1996年   15篇
  1995年   21篇
  1994年   21篇
  1993年   11篇
  1992年   9篇
  1991年   9篇
  1990年   9篇
  1989年   7篇
  1988年   6篇
  1987年   9篇
  1986年   6篇
  1985年   12篇
  1984年   6篇
  1983年   4篇
  1982年   3篇
  1981年   2篇
  1980年   4篇
  1979年   1篇
  1977年   1篇
  1969年   1篇
排序方式: 共有4435条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
High mobility group box ‐1 (HMGB1) represents a common causal agent for various types of diseases, including infective pathologies. This study aimed to investigate the role of HMGB1 in β‐thalassemia major (TM) by evaluating its diagnostic and prognostic role. Fifty‐one TM patients and 30 healthy subjects (HS) were enrolled. Receiver operating characteristics (ROC) analysis was employed to calculate the area under the curve (AUC) for HMGB1 to determine the best cut‐off values capable of identifying infectious episodes. Adjusted risk estimates for infective events were calculated using univariate followed by multivariate Cox proportional hazard regression analysis. Serum HMGB1 levels were higher in TM patients than in HS (14·6 ± 8·7 vs. 2·08 ± 0·9 ng/ml, P < 0·0001). Patients who underwent splenectomy were characterized by lower levels of HMGB1, when compared with patients with an intact spleen (10·2 ± 8 vs. 19·1 ± 7 ng/ml, P = 0·004). ROC analyses revealed an AUC for serum HMGB1 of 0·801, with a sensitivity and specificity of 92·3% and 68·2% to detect an infectious episode. Low HMGB1 levels predicted high risk of infective events (HR: 0·81; P = 0·006). HMGB1 represents a prognostic marker for TM patients and a predictive factor for infectious events.  相似文献   
45.
46.
AIMS: To evaluate possible modifications in the manganese superoxide dismutase (MnSOD) activity during neoplastic transformation of a cirrhotic liver and to find out whether its assessment may have predictive value to identify cirrhotic patients at a higher risk of hepatocellular carcinoma (HCC). METHODS: Seventy-one consecutive subjects with Child-Pugh class A liver cirrhosis were recruited. At the time of enrolment, HCC was diagnosed in 20 cirrhotic patients. The 51 cirrhotic patients without HCC were followed up for the occurrence of tumour by 6-monthly screening for 7 years. During follow-up, 16 patients developed HCC. Seventy healthy subjects formed the control group. MnSOD activity was assayed spectrophotometrically. RESULTS: Serum MnSOD activity was significantly lower in 70 healthy subjects compared with 51 cirrhotic patients and 20 cirrhotic patients with HCC. Cirrhotic patients who developed HCC during follow-up showed significantly higher values of MnSOD activity than HCC-free patients. The best cut-off of MnSOD activity was 0.40 U/ml. At this cut-off, chi2 analysis revealed that MnSOD activity was significantly different between the HCC-free cirrhotic patients and cirrhotic patients who developed HCC. CONCLUSION: The present findings suggest that during neoplastic transformation of cirrhotic liver, an increase in MnSOD activity may occur already during the precancerous phase, making this enzyme a probable malignancy-associated parameter.  相似文献   
47.
Vgamma9/Vdelta2 T cells can contribute to protective immune response against Mycobacterium tuberculosis, although the extent to which and mechanisms by which they could actually protect against human tuberculosis remain unclear. We have previously reported that Vgamma9/Vdelta2 T cells from tuberculin purified protein derivative (PPD)-positive children, either healthy or affected by different clinical forms of tuberculosis, strongly proliferate to different phosphoantigens in vitro, whereas Vgamma9/Vdelta2 T cells from PPD-negative healthy subjects proliferate very poorly. We report here that Vgamma9/Vdelta2 T cells from tuberculous children have an increased proliferative activity, but decreased interferon (IFN)-gamma production and granulysin expression. After successful chemotherapy, the Vgamma9/Vdelta2 T cell proliferative response strongly decreased, whereas IFN-gamma and granulysin production consistently increased. Disease-associated changes in Vgamma9/Vdelta2 T cell effector functions in patients with tuberculosis are consistent with the possibility that these T cells may play a protective role in immune response against M. tuberculosis infection.  相似文献   
48.
ABSTRACT— Severe coagulation defects, as reflected by platelet count and prothrombin time, have always been considered a contraindication to needle biopsy of the liver, but there are very limited data on the actual rate of bleeding in patients with such severe alterations and none whatsoever on the bleeding risk associated with newer, fine-gauge needles that produce less trauma to the liver tissue. In addition, there has never been any evidence that platelet count and/or prothrombin time are the most sensitive indices of bleeding risk. This retrospective study of 85 patients, with platelet counts less than 50 000/mm3 and/or prothrombin times less than 50% of controls, subjected to ultrasound-guided fine-needle liver punctures for diagnostic or therapeutic (percutaneous ethanol injection) purposes showed no bleeding episodes after any of the 229 punctures performed. No type of replacement therapy was administered to correct clotting defects prior to the procedure. Correct pathologic diagnoses were obtained in 81.2% of all patients. Ultrasound-guided fine needle puncture appears to be safer than currently believed in patients with severe clotting defects and deserves further evaluation as an alternative to surgical procedures to diagnose and treat liver lesions, even when severe coagulation impairment is present.  相似文献   
49.
50.

Purpose

Portable polysomnography (PSG) and cardiorespiratory polygraphy are increasingly being used in the assessment of sleep-disordered breathing (SDB) in heart failure patients. Scoring of SDB from cardiorespiratory polygraphy recordings is based only on respiratory signals, while electroencephalographic, electrooculographic and electromyographic channels are taken into account when using PSG recordings. The aim of this study was to assess the agreement between these two scoring methods.

Methods

An overnight sleep study was performed in 67 heart failure patients using a standard portable polysomnograph. Each recording was scored twice, once using all acquired signals (PSG mode) and, after a median of 64 days, using only respiratory signals (cardiorespiratory mode). Agreement was assessed by Bland–Altman analysis and Cohen’s kappa.

Results

We found that (1) more respiratory events were detected using cardiorespiratory analysis [median (25th percentile, 75th percentile), 75 (39, 200) events] compared to analysis of portable PSG [69 (29, 173) events, p?<?0.0001], the extra events being, for the vast majority, central in origin; (2) the apnea/hypopnea index (AHI) estimated by cardiorespiratory polygraphy [11.9 (5.7, 30.8)/h] showed a negligible negative bias relative to portable PSG [15.1 (5.7, 33.6)/h; bias, ?0.8 (?2.9, 0.4)/h, p?=?0.0002]; (3) limits of agreement between the two systems (?6.2/h, 1.7/h) were much smaller than those previously observed between two nights using the same scoring modality; and (4) the kappa coefficient using categorised AHI was 0.89 (95 % confidence interval (CI) 0.82, 0.96).

Conclusions

We found a high degree of agreement between the AHIs obtained from the two scoring methods, thus suggesting that cardiorespiratory polygraphy may be used as an alternative to portable PSG in the assessment of SDB in heart failure patients.
  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