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   62005篇
  免费   3963篇
  国内免费   999篇
耳鼻咽喉   475篇
儿科学   1570篇
妇产科学   1595篇
基础医学   7320篇
口腔科学   1078篇
临床医学   5556篇
内科学   14496篇
皮肤病学   1144篇
神经病学   5600篇
特种医学   1992篇
外国民族医学   2篇
外科学   7722篇
综合类   2157篇
现状与发展   1篇
一般理论   12篇
预防医学   4186篇
眼科学   974篇
药学   5073篇
  8篇
中国医学   1030篇
肿瘤学   4976篇
  2023年   542篇
  2022年   1359篇
  2021年   2154篇
  2020年   1330篇
  2019年   1585篇
  2018年   1753篇
  2017年   1369篇
  2016年   1414篇
  2015年   1818篇
  2014年   2444篇
  2013年   3071篇
  2012年   4171篇
  2011年   4364篇
  2010年   2520篇
  2009年   2210篇
  2008年   3570篇
  2007年   3610篇
  2006年   3351篇
  2005年   3212篇
  2004年   2880篇
  2003年   2533篇
  2002年   2317篇
  2001年   1517篇
  2000年   1407篇
  1999年   1333篇
  1998年   579篇
  1997年   442篇
  1996年   428篇
  1995年   353篇
  1994年   320篇
  1993年   259篇
  1992年   713篇
  1991年   605篇
  1990年   571篇
  1989年   580篇
  1988年   484篇
  1987年   437篇
  1986年   417篇
  1985年   333篇
  1984年   279篇
  1983年   230篇
  1982年   131篇
  1981年   109篇
  1979年   220篇
  1978年   137篇
  1977年   118篇
  1974年   128篇
  1973年   130篇
  1972年   129篇
  1971年   112篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Di Benedetto  P.  Giorgini  T.  Delneri  C.  Biasutti  E. 《Neurological sciences》2006,27(4):s320-s322
Neurological Sciences - Bladder and urethra are innervated peripherally by pelvic parasympathetic, lumbar sympathetic and pudendal nerves; but a complex of brain networks is involved in the...  相似文献   
132.
Cancer cells elaborate metalloproteinases which may play a role in invasion and metastasis. The serum level of the M(r) 72,000 type IV collagenase (MMP-2) was measured in 87 lung cancer patients. Stage IV cancer levels were significantly elevated (P less than 0.0001) compared to normal sera. A significant difference (P less than 0.01) was found between enzyme levels in the presence versus the absence of distant metastasis. For 29 patients treated with combination chemotherapy, a positive relationship was noted between response failure and elevated enzyme levels. Serum metalloproteinase levels may provide information relevant to prognosis as well as treatment decisions.  相似文献   
133.
BACKGROUND: Coronary vasculopathy is the main cause of cardiac graft failure. Because yearly coronary angiography is invasive in children, a non-invasive method for detecting graft vasculopathy is needed. The aim of this study was to test dobutamine-stress echocardiography in a pediatric population to determine its feasibility, safety and reliability in the detection of graft coronary artery disease. METHODS: Eighteen patients, aged 2 days to 16.8 years at transplantation (mean 8.4 years), underwent 44 dobutamine-stress echocardiography (DSE) exams, at a follow-up of 1.1 to 11.8 years (mean 5.1 years). Selective coronary angiography was performed for comparison. Echocardiographic recordings were obtained in 4 standard views of the left ventricle and measurements carried out within the frames of a 16-segment model. Segmental scores of contractility were obtained for each segment and a total segmental contractility index was calculated at each stage. RESULTS: All patients reached the maximum dose stage. Maximum heart rate was 57% to 90% of predicted maximum. Maximum systolic blood pressure reached 190 mmHg. Segmental scores were normal in 37 and abnormal in 7 cases. Echographic results were concordant with angiography in 82% and discordant in 18% of the cases (4 negative DSEs with minor angiographic lesions, 2 positive DSEs with normal angiography), but there was no significant angiographic lesion with normal DSE. CONCLUSIONS: DSE is a safe and highly feasible non-invasive technique in transplanted children. A normal DSE study successfully predicts the absence of significant coronary artery disease in the post-transplant population.  相似文献   
134.
超声心动图对62例房间隔缺损封堵术后心功能变化的评价   总被引:5,自引:0,他引:5  
目的:应用超声心动图评价房间隔缺损(ASD)封堵术前后左、右心室功能的变化。方法:对62例成功施行经皮穿刺ASD封堵术的患者进行研究。所有患者在术前、术后1周及1个月分别进行超声心动图检查.观察心脏大小及功能的改变。结果:ASD封堵术后,左室舒张末期前后径、左室舒张末期容积、左室每搏量及左室射血分数增大,而左室收缩末期容积未见明显改变;右室舒张末期前后径、右室舒张末期容积、右室收缩末期容积、右室每搏量、右室射血分数及右室心肌工作指数均减小。结论:经皮穿刺ASD封堵治疗既可减轻右室容量负荷,改善右室功能,也可改善左室的收缩功能:超声心动图对ASD封堵前后心脏血流动力学评价及疗效的观察起了重要的作用。  相似文献   
135.
BACKGROUND: Sodium removal (NaR) may have a major impact on the survival of peritoneal dialysis patients. The dialysate/plasma sodium concentration ratio (D/P(Na)) is an indirect index of transcellular water transport by aquaporin channels, and thus of ultrafiltration. Sodium concentration can be assessed by means of flame photometry (F), and direct (D-ISE) or indirect ion-selective electrodes (I-ISE), but these methods have different properties. I-ISE is being used increasingly in clinical laboratories. The aim of this study was to evaluate NaR and D/P(Na) using the three different measurement methods. METHODS: We performed peritoneal equilibration tests (PETs) in 44 peritoneal dialysis patients and calculated the NaR. We also calculated D/P(Na) during the test; plasma and dialysate sodium concentrations were measured by F, D-ISE and I-ISE. RESULTS: NaR was lower (P<0.001) with D-ISE (69+/-29 mmol) than with F (81+/-29 mmol) or I-ISE (79+/-28 mmol). D/P(Na) was also lower at baseline (0.92+/-0.02 vs 0.95+/-0.02 and 0.95+/-0.02; P<0.001), after 60 min (0.87+/-0.03 vs 0.90+/-0.03 and 0.90+/-0.03; P<0.001) and at the end of PET (0.88+/-0.04 vs 0.92+/-0.04 and 0.92+/-0.04; P<0.001) when measured by D-ISE in comparison with F and I-ISE, respectively. CONCLUSIONS: NaR and D/P(Na) were lower when measured by the D-ISE method compared with the F and I-ISE methods. NaR and D/P(Na) were similar when measured by F or I-ISE. I-ISE can be used reliably in the evaluation of NaR and D/P(Na) in everyday clinical practice of peritoneal dialysis.  相似文献   
136.
Benign neonatal sleep myoclonus (BNSM), characterized by myoclonic jerks of the extremities only in non-REM sleep, occurs in the first months of life with spontaneous disappearance within 3-4 months. We examined five siblings with typical BNSM, at the 3-10 years follow-up neurological examination. Psychomotor development, cognitive functions and EEG were completely normal. These cases confirm that BNSM is a self limited and nonepileptic disorder.  相似文献   
137.
138.
A series of 1153 fine-needle aspiration biopsies (FNAB) of breast masses obtained during the period 1985 to 1988 in one institution was examined. The following diagnostic accuracy values were found: sensitivity, 93.0%; specificity, 92.4%; predictive positive value, 93.7%; and efficiency, 92.8%. These results were compared with a previously published series for the period 1976 to 1984. The diagnostic accuracy values did not differ significantly between the two series.  相似文献   
139.
The intensity dependence of the auditory-evoked potentials (IDAP) is inversely related to serotonergic tone. Depression is frequently observed after stroke, associated with cognitive impairment and increased mortality. Aim of this study was to investigate the serotonergic tone in acute stroke patients by IDAP. Consecutive patients with an acute stroke admitted in our stroke unit were evaluated using clinical and instrumental examinations and compared with healthy controls. The IDAP was calculated as the linear amplitude/stimulus intensity function (ASF) slope, by measuring the peak-to-peak amplitude of Nl-P2 on four blocks of different stimulus intensities. Twenty patients were enrolled; 11 had a right brain infarction; nine had depressive symptoms (DS). The ASF slope of the auditory-evoked potentials was markedly increased in stroke patients compared with controls ( P  = 0.021). Stroke patients with DS had a significant steeper ASF slope than controls ( P  = 0.017). There was no statistical difference in ASF slope between stroke patients without DS and controls. Post-stroke depression pathophysiology is still debated. Our study suggests that in acute stroke patients with DS, there is a direct involvement of the serotonergic system, regardless the degree of disability and the site of the lesion.  相似文献   
140.
Risk of death from acute pancreatitis   总被引:5,自引:0,他引:5  
Summary Conclusions The analysis of all the data available in 192 patients at 24 h from admission shows that only serum glucose above 250 mg/dL (13.88 mmol/L) and serum creatinine above 2 mg/dL (176.8 μmol/L) are prognostic factors of death (P<0.0001). When, however, pathological chest X-rays are also considered in a subset of 149 patients, these and serum creatinine are prognostic factors of death with odds ratios of 2.9 (95% CL 1.3–6.3) and 9.4 (95% CL 2.2–40.7), respectively (P<0.0001). Background In patients suffering from acute pancreatitis, neither Ranson scores nor Glasgow criteria evaluation at 24 h yield a sufficiently reliable prognosis of the risk of death from the first acute attack. Methods After excluding posttraumatic, postsurgical, and post-ERCP acute pancreatitis, we selected 192 consecutive patients admitted in the first instance to our center for a first attack, distinguishing between patients who died and patients who survived. We used Cox's model to analyze the prognostic weight of variables available within 24 h of admission (sex, age, alcohol intake, smoking habits, 17 biochemical tests, body mass index, chest X-rays, body temperature, and shock status). Results Seventeen (8.8%) patients died; mortality showed a decreasing trend over the period of years considered and was correlated, among other things, with necrotizing type of pancreatitis, idiopathic etiology, and shock status on admission.  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