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   3689篇
  免费   139篇
  国内免费   33篇
耳鼻咽喉   14篇
儿科学   59篇
妇产科学   38篇
基础医学   498篇
口腔科学   22篇
临床医学   741篇
内科学   810篇
皮肤病学   19篇
神经病学   303篇
特种医学   102篇
外科学   495篇
综合类   20篇
预防医学   175篇
眼科学   63篇
药学   258篇
中国医学   7篇
肿瘤学   237篇
  2023年   10篇
  2022年   13篇
  2021年   35篇
  2020年   17篇
  2019年   30篇
  2018年   45篇
  2017年   45篇
  2016年   32篇
  2015年   60篇
  2014年   94篇
  2013年   118篇
  2012年   241篇
  2011年   278篇
  2010年   143篇
  2009年   158篇
  2008年   273篇
  2007年   287篇
  2006年   277篇
  2005年   297篇
  2004年   281篇
  2003年   305篇
  2002年   251篇
  2001年   31篇
  2000年   37篇
  1999年   38篇
  1998年   46篇
  1997年   35篇
  1996年   34篇
  1995年   44篇
  1994年   35篇
  1993年   22篇
  1992年   20篇
  1991年   24篇
  1990年   14篇
  1989年   15篇
  1988年   15篇
  1987年   15篇
  1986年   20篇
  1985年   9篇
  1984年   17篇
  1983年   9篇
  1982年   14篇
  1981年   11篇
  1980年   11篇
  1979年   14篇
  1978年   5篇
  1977年   6篇
  1976年   5篇
  1974年   5篇
  1973年   4篇
排序方式: 共有3861条查询结果,搜索用时 46 毫秒
1.
BACKGROUND: Abnormal glucose tolerance is a frequent co-morbidity in cystic fibrosis patients (CF), and is associated with a worse prognosis. The objectives are to investigate (a) the relative contribution of insulinopenia and insulin resistance (IR) for glucose tolerance and (b) the association between various glucose parameters and CF clinical status. METHODS: Oral glucose tolerance tests were performed in 114 consecutive CF patients not known to be diabetic as well as 14 controls similar for age and BMI. RESULTS: Abnormal glucose tolerance was found in 40% of patients with CF: 28% had impaired glucose tolerance (IGT) and 12% had new cystic fibrosis related diabetes (CFRD). Compared to control subjects, all CF patients were characterized by an increased glucose excursion (AUC). While reduced early insulin release characterised CF, IGT and CFRD patients also present IR thus both mechanisms significantly contribute to glucose tolerance abnormalities. Increased glucose AUC and reduced early insulin release but not glucose tolerance categories were associated with a reduced pulmonary function (FEV(1)). CONCLUSION: In CF, early insulin secretion defect but also IR contribute to glucose intolerance. Early in the course of the disease, increased glucose AUC and reduced early insulin secretion are more closely associated with a worse clinical status than conventional glucose tolerance categories.  相似文献   
2.
OBJECTIVE: The aim of this paper is to assess the accuracy of an algorithm implemented by PRAXIM in the SURGETICS navigation station for detection of the hip center. This study will assess the robustness and accuracy of the algorithm in various clinical situations such as those involving non-sphericity of the femoral head, motion of the pelvis during hip center detection, and restricted range of motion. MATERIALS AND METHODS: The localization of the hip center, based on kinematics, relies on the recording of n successive positions of the femoral rigid body in the localizer reference system during a passive circumduction motion of the hip joint. Therefore, the shape of the clouds of points acquired may vary from one acquisition to the next. To allow a comprehensive study of the consequences of these variations for hip center detection, we developed a simulator to generate numerous clouds of points. Results given subsequently for each test are the values of the difference between the femoral mechanical axis computed with C(c), the computed hip center, and the same axis computed with C(o), the reference hip center. RESULTS: Test 1: Sensitivity to noise. The errors ranged from 3.33 E - 12 (SD 3.29E - 12) for a noise of 0 mm to 8.18E - 1 (SD - 7.05E - 1) for a noise of 15 mm. Test 2: Sensitivity to the shape of the acquisition motion. All trajectories gave an error < 1 degrees . Test 3: Sensitivity to restricted range of motion. No value > 1 degrees was found during this test. Test 4: Sensitivity to the distance between two points of the cloud. No value > 0.5 degrees was found during this test. Test 5: Sensitivity to the number of points included in the cloud. No value > 1 degrees was found during this test. CONCLUSIONS: The Surgetics algorithm is robust to noise, can compensate for pelvic motion, and can be used even in the case of restricted range of motion.  相似文献   
3.
The effects of scopolamine, an anticholinergic drug, of trimipramine, a tricyclic antidepressant with both anticholinergic and sedative properties, of diazepam and a placebo, on explicit memory and repetition priming were assessed using a free-recall task and a word-stem completion task. Forty-eight healthy volunteers took part in this double-blind study. Diazepam provoked a dissociation between free recall, which was profoundly impaired, and word completion, which was spared. No significant changes in memory performances were observed in the scopolamine group; however, a significant correlation between explicit and implicit memory performances was observed in this group. At the low dose used, the effects of trimipramine on memory were mild. The results suggest that the cholinergic system is involved in the priming effect.  相似文献   
4.
Interleukin-6 (IL-6) was determined in serum and peritoneal dialysis effluent (PDE) of patients on chronic ambulatory peritoneal dialysis (CAPD) by a biological assay measuring the proliferation of the IL-6-dependent 7TD1 cell line. Six patients free of peritonitis displayed low but significant levels of IL-6 (mean +/- 42 pg/ml) in PDE, while IL-6 was undetectable in serum. In 6 patients with staphylococcal peritonitis, a tremendous increase in PDE levels of IL-6 was noted (range: 5,832-37,491 pg/ml), while serum IL-6 remained either undetectable or on a low level except in one case. After 5 days of antibiotic treatment, IL-6 levels in PDE returned to basal values. We conclude that CAPD results in an intraperitoneal secretion of IL-6 which is markedly but transiently increased during peritonitis episodes.  相似文献   
5.
[(123)I]Metaiodobenzylguanidine ([(123)I]MIBG) cardiac scintigraphy could be helpful to differentiate Parkinson's disease (PD) from multiple system atrophy (MSA), demonstrating that, in PD with autonomic failure but not in MSA, there is a myocardial postganglionic sympathetic dysfunction. To investigate whether this method is more sensitive than standard autonomic testing to detect early involvement of sympathetic cardiac efferent, we analyse MIBG myocardial uptake in 8 PD patients with normal autonomic testing (nondysautonomia PD group, NDPD) in comparison with 10 PD patients with abnormal autonomic testing (dysautonomia PD group, DPD) and 10 MSA patients. Global MIBG uptake was assessed using the ratio of [(123)I]MIBG uptake in the heart to the upper mediastinum (H/M) on planar scintigraphic data. Regional MIBG uptake was determined on two single photon emission tomography scans in regions of the left ventricle. The mean H/M ratios were significantly different among the three groups (P < 0.0001). H/M ratios of both NDPD and DPD patients groups (H/M = 1.83 +/- 0.50 and 1.24 +/- 0.40, respectively) were significantly lower than in MSA patients (H/M = 2.52 +/- 0.60). However, in NDPD patients, H/M was significantly higher than in DPD patients. When compared to MSA patients, NDPD patients showed a regional reduction in MIBG uptake in all left ventricle regions markedly in the apex and the inferior wall. Our results suggest that MIBG myocardial scintigraphy (analysis of both H/M ratio and regional MIBG uptake) may be more sensitive than standard autonomic testing for the early detection of silent autonomic dysfunction in PD.  相似文献   
6.
Summary Simultaneous tumors are rarely encountered during the course of acute leukemias. We report on a case of seminoma of the testis that occurred during the evolution of acute myelogenous leukemia. To our knowledge, this stimultaneous association has not previously been described, but a causal relationship was not apparent in the present case. The likelihood of a common carcinogenesis existed, but direct exposure to carcinogens could not be established. Although the results of a physical examination and echography were normal at the time of diagnosis, we cannot exclude the presence of microscopic cancer of the testis. Since the dissemination pattern of seminoma is usually slower than that observed in this case and the disease remains limited to the lymph nodes for long periods following dissemination, the rapid development of the present case might have been attributable to the immunosuppression and the scrotal sepsis that occurred during the induction therapy. Immunosuppression might have stimulated the progression of a primary microscopic seminoma and the development of metastasis, whereas the scrotal sepsis and inflammation might have favored the occurrence of metastasis through bypass of the lymphatic barrier.  相似文献   
7.
8.
May garlic have beneficial effects on cardiovascular and metabolic diseases?Some data support that garlic may have benefical medicinal functions on dyslipidemia, hypertension and diabetes mellitus. However the results of clinical trials are controversial. Several metaanalysis and a systematic review didn’t confirm that garlic or its compounds had significant effects on plasma lipids or on blood pressure. The hypoglycaemic effect was supported by any randomised clinical study. Contrary to the assertion of many physicians and patients, consumption of garlic can’t be considered as an alternative treatment for dyslipidemia or hypertension.  相似文献   
9.
Non-invasive ambulatory recordings of blood pressure and heart rate were performed using a Spacelabs device during day and night periods in patients with Parkinson's disease with (n = 19) or without orthostatic hypotension (n = 19). In patients with orthostatic hypotension, the average systolic and diastolic blood pressure during the night (137 ± 5/80 ± 3 mmHg) was higher (p < 0.05) than during the day period (121 ± 3/76 ± 2 mmHg). In patients without orthostatic hypotension, a decrease in blood pressure was recorded during the nocturnal period. In patients with orthostatic hypotension, the blood pressure variability was higher (p < 0.05) during the day (systolic: 14.6 ± 1.3%; diastolic: 16.5 ± 1.0%) than during the night (systolic: 9.1 ± 0.8%; diastolic: 10.8 ± 1.1%). The blood pressure load (percentage of values above 140/90 mmHg) during the night was significantly higher than during the day for both systolic (41.2 ± 8.1 vs. 19.6 ± 4.7%) and diastolic blood pressure (24.9 ± 6.9 vs. 16.3 ± 4.9%). There was a decrease in heart rate in both groups during the night. A fall of 25 mmHg or more in systolic blood pressure after meals occurred in ten patients with orthostatic hypotension and in one patient without orthostatic hypotension. These results indicate that orthostatic hypotension in Parkinson's disease is associated with specific modifications of ambulatory blood pressure including loss of circadian rhythm of blood pressure, increased diurnal blood pressure variability and post-prandial hypotension.  相似文献   
10.
A significant increase of cutaneous laser Doppler flowmetry was found before blood flow decreases with increasing pressure during a 5 mmHg min−1 increase of pressure strain on the finger. Pre-treatment with a local anaesthetic or chronically applied capsaicin, resulted in the disappearance of the vasodilatory response. These results suggest an original vasodilatory axon reflex response to non-noxious pressure strain which is initiated by capsaicin-sensitive nerve terminals in the human skin.  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