全文获取类型
收费全文 | 536篇 |
免费 | 25篇 |
国内免费 | 19篇 |
专业分类
儿科学 | 26篇 |
妇产科学 | 3篇 |
基础医学 | 48篇 |
口腔科学 | 15篇 |
临床医学 | 64篇 |
内科学 | 123篇 |
皮肤病学 | 9篇 |
神经病学 | 34篇 |
特种医学 | 118篇 |
外科学 | 38篇 |
综合类 | 18篇 |
预防医学 | 40篇 |
眼科学 | 7篇 |
药学 | 23篇 |
中国医学 | 1篇 |
肿瘤学 | 13篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 18篇 |
2012年 | 25篇 |
2011年 | 18篇 |
2010年 | 29篇 |
2009年 | 19篇 |
2008年 | 12篇 |
2007年 | 21篇 |
2006年 | 11篇 |
2005年 | 21篇 |
2004年 | 23篇 |
2003年 | 14篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 23篇 |
1997年 | 17篇 |
1996年 | 12篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1955年 | 2篇 |
1945年 | 2篇 |
1940年 | 2篇 |
排序方式: 共有580条查询结果,搜索用时 0 毫秒
101.
IH Khan MK Campbell D Cantarovich GR Catto C Delcroix N Edward C Fontenaille HW van Hamersvelt IS Henderson RA Koene M Papadimitriou E Ritz C Ramsay D Tsakiris AM MacLeod 《American journal of kidney diseases》1998,31(3):473-478
The need to evaluate the effectiveness of clinical practice to justify expensive therapy in the face of financial constraints in all areas of health care delivery makes it necessary to identify groups of patients who are likely to benefit most from treatment. Various risk stratification methods have been used for analyzing survival probabilities for patients receiving renal replacement therapy. Complicated risk stratification methods produce large numbers of risk groups of small sizes, which makes comparison between individual centers difficult. We compared three simple methods of risk stratification, that divided patients into low-, medium-, and high-risk groups, in a cohort of 1,407 patients who commenced renal replacement therapy in five European countries during a 7-year period. Method 1 considered age (>55 years) and diabetes alone; method 2 used a higher age limit (>70 years) and comorbid illnesses, including those other than diabetes; and method 3 used only the number of comorbidities (none, 1, or > or =2) for stratification. Kaplan-Meier survival curves were constructed for comparison between risk groups and Cox's regression model used to assess strength of relationship with mortality. Although patient survival was significantly different between the low-, medium-, and high-risk groups using all three methods, Cox's regression analysis showed that method 2 provided the greatest discrimination between risk groups. In predicting mortality, method 2 (based on comorbidities and age) showed the highest sensitivity and specificity (84% and 80%, respectively) compared with method 1 (80% and 74%) and method 3 (64% and 82%). Validation of this approach in other populations in a prospective study is required before this method, which takes into account the influences of both age and comorbidity for risk stratification, can be used for comparing survival data and for presenting results of renal replacement therapy. 相似文献
102.
Identifying true brain interaction from EEG data using the imaginary part of coherency. 总被引:2,自引:0,他引:2
Guido Nolte Ou Bai Lewis Wheaton Zoltan Mari Sherry Vorbach Mark Hallett 《Clinical neurophysiology》2004,115(10):2292-2307
OBJECTIVE: The main obstacle in interpreting EEG/MEG data in terms of brain connectivity is the fact that because of volume conduction, the activity of a single brain source can be observed in many channels. Here, we present an approach which is insensitive to false connectivity arising from volume conduction. METHODS: We show that the (complex) coherency of non-interacting sources is necessarily real and, hence, the imaginary part of coherency provides an excellent candidate to study brain interactions. Although the usual magnitude and phase of coherency contain the same information as the real and imaginary parts, we argue that the Cartesian representation is far superior for studying brain interactions. The method is demonstrated for EEG measurements of voluntary finger movement. RESULTS: We found: (a) from 5 s before to movement onset a relatively weak interaction around 20 Hz between left and right motor areas where the contralateral side leads the ipsilateral side; and (b) approximately 2-4 s after movement, a stronger interaction also at 20 Hz in the opposite direction. CONCLUSIONS: It is possible to reliably detect brain interaction during movement from EEG data. SIGNIFICANCE: The method allows unambiguous detection of brain interaction from rhythmic EEG/MEG data. 相似文献
103.
104.
Pseudoaneurysm is a well-documented but rare complication of retrograde femoral arterial puncture. We present six patients in whom pseudoaneurysm complicated this procedure. The pseudoaneurysm arose from the superficial femoral artery in five patients and from the profunda femoris artery in one. An arteriovenous fistula also arose from the superficial femoral artery in one patient. In no patient did the pseudoaneurysm arise from the common femoral artery. Two mechanisms are postulated as to why pseudoaneurysms rarely complicate puncture of the common femoral artery. 相似文献
105.
David Carmody Aoife Doyle Richard GR Firth Maria M Byrne Sean Daly Fionnuala Mc Auliffe Micheal Foley Samuel Coulter‐Smith Kinsley Brendan T 《Pediatric diabetes》2010,11(2):111-115
Carmody D, Doyle A, Firth RGR, Byrne MM, Daly S, Mc Auliffe F, Foley M, Coulter‐Smith S, Kinsley BT. Teenage pregnancy in type 1 diabetes mellitus Younger maternal age at delivery has been linked to adverse reproductive outcomes. Pregnancy complicated by type 1 diabetes mellitus (T1DM) is also associated with adverse pregnancy outcomes. Optimising diabetic glycaemic control prior to pregnancy is known to reduce the rate of congenital abnormalities and improve pregnancy outcomes. Teenage pregnancies are not usually planned and little data exist on teenage pregnancy complicated by T1DM. We sought to identify the glycemic control achieved in teenage pregnancy with T1DM and to clarify if there is an associated increase in adverse pregnancy outcomes compared to those seen in older women with T1DM. We compared outcomes in 18 teenagers (TG) with 582 older women with T1DM (CON) from 1995–2007. TG booked to the combined diabetes‐obstetrical service at a median gestational age of 11 weeks (range 6–22) compared to 7 weeks in CON (range 4–40, p < 0.02). Glycaemic was worse in TG compared to CON at 13, 26 and 35 weeks gestation, despite higher insulin doses. First trimester miscarriage rate did not differ between groups. Major congenital anomaly rate was 6.2% (1/16) compared to 3.2% in CON. This preliminary study has demonstrated that pregnant teenage women with T1DM book later to specialised care and have worse glycaemic control in pregnancy compared to older women with T1DM. This group also appear to be more insulin resistant than older women in early pregnancy. Our data would suggest that teenagers with type 1 diabetes mellitus may constitute a high‐risk group for adverse pregnancy outcomes. 相似文献
106.
A Marciniak GR Sutherland M Marciniak P Claus B Bijnens M Jahangiri 《European journal of echocardiography》2009,10(1):112-119
Aims: Early left ventricular (LV) dysfunction in asymptomatic patientswith severe aortic regurgitation (AR) may go undetected dueto the lack of a sufficiently sensitive diagnostic tool. Ultrasonicstrain/strain rate (S/SR) imaging should now provide such sensitivityin detecting early dysfunction in regional LV systolic deformation.The aim of this study was to understand and define the changesin LV regional systolic deformation based on S/SR imaging inpatients with asymptomatic or minimally symptomatic AR. Methods and results: Eighty-one individuals were studied: 59 asymptomatic patientswith isolated non-ischaemic AR who were divided into three sub-groupssuch as mild, moderate, and severe AR and 22 age-matched healthysubjects. All patients underwent standard echocardiographicexaminations including a tissue Doppler imaging study. For LVradial deformation, the posterior wall (LVPW) was examined.To assess LV longitudinal deformation, S and SR data were acquiredfrom the LV lateral wall and septum. Radial as well as longitudinalpeak systolic SRs were significantly decreased in patients withboth moderate AR (LVPW, P = 0.0009; septum, P = 0.03; LV lateralwall, P = 0.0009) and severe AR (P < 0.0001) compared withhealthy subjects. Changes in regional LV deformation correlatedinversely both with LV end-diastolic volume and with end-systolicvolume. Conclusions: Strain rate imaging is a sensitive tool in detecting the spectrumof changes in radial and longitudinal deformation in asymptomaticor minimally symptomatic patients with AR. The index where volumewas corrected by deformation should form the basis for predictingsubclinical LV dysfunction in patients with increasing LV dilatation. 相似文献
107.
Anne G Wheaton Geraldine S Perry Daniel P Chapman Lela R McKnight-Eily Letitia R Presley-Cantrell Janet B Croft 《BMC public health》2011,11(1):295
Background
Over the past 50 years, the average sleep duration for adults in the United States has decreased while the prevalence of obesity and associated outcomes has increased. The objective of this study was to determine whether perceived insufficient sleep was associated with body mass index (BMI) in a national sample. 相似文献108.
培养心肌细胞牵张刺激装置的建立及应用 总被引:2,自引:2,他引:2
1 方法 牵张刺激装置的制作如模式图 1.制作实验模型采用材料为有机玻璃板、2 4孔培养板、硅胶膜 (厚度 0 .2 2 μm) .硅胶膜从平面圆形变为球形时 ,面积扩大的百分比 =(S球 -S园 ) /S园 ,其中S球 =AD2 ,S园 =r2 ,而AD2 =h2 +r2 ,其中r为孔的半径 ,h为膜升高的高度图 2 .通过控制h的大小 ,可控制膜被牵拉的强度 .本实验采用使膜面积扩大 2 0 %的强度 ,故h =4mm[1] .参照Kassiri等[2 ,3 ] 方法进行心肌细胞的分离培养 .生长有贴壁心肌细胞的 2 4孔板被固定于牵张装置 ,缓慢充气使硅胶膜向上凸起 4mm ,分别维持… 相似文献
109.
Meniscal injuries: detection using MR imaging 总被引:15,自引:0,他引:15
Reicher MA; Hartzman S; Duckwiler GR; Bassett LW; Anderson LJ; Gold RH 《Radiology》1986,159(3):753-757
Both retrospective and blinded analyses of thin-section, high-resolution magnetic resonance (MR) images of the knee joint, produced using a solenoid surface coil, indicate that MR imaging is an effective technique for evaluating meniscal injuries. Images of 49 patients were evaluated, and the results were correlated with those of subsequent arthroscopy. A grading scale was developed to rate the index of suspicion of a meniscal tear based on the MR images. Overall, approximately 80% of menisci rated grade 4 (definite tear) or 3 (probable tear) were found to have corresponding tears at arthroscopy. In many other patients with a grade 4 or 3 meniscus in whom a corresponding tear was not found arthroscopically, meniscal tears at other sites or other abnormalities were correctly diagnosed using MR. A majority of the false-positive MR images involved the posterior horns of the menisci, the sites of most false-negative arthroscopic diagnoses. The predictive value of a negative MR image was almost 100%. Even in patients with moderate-to-large effusions, the menisci were accurately evaluated. The results imply that MR imaging is useful in the preoperative evaluation of suspected meniscal tears. 相似文献