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   352篇
  免费   36篇
  国内免费   1篇
儿科学   2篇
妇产科学   12篇
基础医学   70篇
口腔科学   28篇
临床医学   87篇
内科学   38篇
皮肤病学   1篇
神经病学   37篇
特种医学   30篇
外科学   36篇
预防医学   8篇
眼科学   13篇
药学   23篇
肿瘤学   4篇
  2023年   9篇
  2022年   3篇
  2021年   10篇
  2020年   8篇
  2019年   12篇
  2018年   12篇
  2017年   10篇
  2016年   6篇
  2015年   18篇
  2014年   22篇
  2013年   12篇
  2012年   27篇
  2011年   38篇
  2010年   17篇
  2009年   18篇
  2008年   22篇
  2007年   15篇
  2006年   18篇
  2005年   11篇
  2004年   13篇
  2003年   10篇
  2002年   18篇
  2001年   6篇
  2000年   4篇
  1999年   2篇
  1998年   9篇
  1997年   4篇
  1996年   4篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1992年   7篇
  1991年   3篇
  1990年   2篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1974年   1篇
排序方式: 共有389条查询结果,搜索用时 46 毫秒
1.
There is limited information regarding oral health status and other predictors of oral health‐related quality of life. An association between oral health status and perceived oral health‐related quality of life (OHQOL) might help clinicians motivate patients to prevent oral diseases and improve the outcome of some dental public health programs. This study evaluated the relationship between older persons' OHQOL and their functional dentition, caries, periodontal status, chronic diseases, and some demographic characteristics. A group of 733 low‐income elders (mean age 72.7 ISD=4.71, 55.6% women, 55.1% members of ethnic minority groups in the U.S. and Canada) enrolled in the TEETH clinical trial were interviewed and examined as part of their fifth annual visit for the trial. OHQOL was measured by the Geriatric Oral Health Assessment Index (GOHAI); oral health and occlusal status by clinical exams and the Eichner Index; and demographics via interviews. Elders who completed the four‐year assessment had an average of 21.5 teeth (SD=6.9). with 8.5 occluding pairs (SD=4.6), and 32% with occlusal contacts in all four occluding zones. Stepwise multiple regressions were conducted to predict total GOHAI and its subscores (Physical, Social, and Worry). Functional dentition was a less significant predictor than ethnicity and being foreign‐bom. These variables, together with gender, years since immigrating, number of carious roots, and periodontal status, could predict 32% of the variance in total GOHAI, 24% in Physical, 27% in Social, and 21 % in the Worry subscales. These findings suggest that functional dentition and caries influence older adults' OHQOL, but that ethnicity and immigrant status play a larger role.  相似文献   
2.
The duration of the late exteroceptive suppression period (ES2) of temporal muscle EMG activity has been reported to be reduced in patients suffering from chronic tension-type headache. Methods of recording and analysing ES2 have varied between centers and reproducibility of results within subjects , although insufficiently studied, has generally been poor. ES2 was investigated in 30 healthy subjects, using a computerized technique of recording, rectifying and averaging the EMG signals. Hour to hour and week to week variations of ES2 durations were calculated, and the influence of pain during a cold pressor test and of sustained muscle contraction on ES2 durations was investigated. The intra-individual variation of ES2 durations was 16.0% from hour to hour and 20.7% from week to week. The inter-individual variation was 36.7%. The present method for analysis of ES2 periods proved to be reliable, as the intra-observer variation was 4.2% and the inter-observer variation 4.6%. ES2 periods were significantly shorter on the first compared to the second day of examination ( p = 0.006) and during experimental pain ( p = 0.0005). We recommend the use of the computerized averaging technique in future studies and caution against the dependence of results upon factors such as conditioning and pain.  相似文献   
3.
The platelet and the neuron: Two cells in focus in migraine   总被引:1,自引:0,他引:1  
Reports of platelet abnormalities in migraine are abundant, and the present paper discusses the role of platelets in the migraine aetiology. Platelets are considered good models for pre- and post-synaptic functions in serotonergic neurons. We propose that migraine is associated with a lowered threshold for stimulus response in both platelets and serotonergic neurons and that the alterations in platelet function reflect central serotonergic disturbances. The platelet abnormalities in migraine approach those found in depression, and there are several links between the two disorders. The clinical significance of platelet hyperactivity in migraineurs for the occurrence of thrombotic disorders is also discussed. Studies of platelet functions in migraine, using platelets as models for serotonergic neurons, may broaden our understanding of the neuronal processes that take place during a migraine attack. The platelet can also be an investigative tool for better understanding of the modes of action of anti-migraine drugs.  相似文献   
4.
5.
To test the hypothesis that the increased sympathetic tonus elicited by chronic hypoxia is needed to match O(2) delivery with O(2) demand at the microvascular level eight male subjects were investigated at 4559 m altitude during maximal exercise with and without infusion of ATP (80 mug (kg body mass)(-1) min(-1)) into the right femoral artery. Compared to sea level peak leg vascular conductance was reduced by 39% at altitude. However, the infusion of ATP at altitude did not alter femoral vein blood flow (7.6 +/- 1.0 versus 7.9 +/- 1.0 l min(-1)) and femoral arterial oxygen delivery (1.2 +/- 0.2 versus 1.3 +/- 0.2 l min(-1); control and ATP, respectively). Despite the fact that with ATP mean arterial blood pressure decreased (106.9 +/- 14.2 versus 83.3 +/- 16.0 mmHg, P < 0.05), peak cardiac output remained unchanged. Arterial oxygen extraction fraction was reduced from 85.9 +/- 5.3 to 72.0 +/- 10.2% (P < 0.05), and the corresponding venous O(2) content was increased from 25.5 +/- 10.0 to 46.3 +/- 18.5 ml l(-1) (control and ATP, respectively, P < 0.05). With ATP, leg arterial-venous O(2) difference was decreased (P < 0.05) from 139.3 +/- 9.0 to 116.9 +/- 8.4(-1) and leg .VO(2max) was 20% lower compared to the control trial (1.1 +/- 0.2 versus 0.9 +/- 0.1 l min(-1)) (P = 0.069). In summary, at altitude, some degree of vasoconstriction is needed to match O(2) delivery with O(2) demand. Peak cardiac output at altitude is not limited by excessive mean arterial pressure. Exercising leg .VO(2peak) is not limited by restricted vasodilatation in the altitude-acclimatized human.  相似文献   
6.
The age‐dependent penetrance of organ manifestations in Marfan syndrome (MFS) is not known. The aims of this follow‐up study were to explore how clinical features change over a 10‐year period in the same Norwegian MFS cohort. In 2003–2004, we investigated 105 adults for all manifestations in the 1996 Ghent nosology. Ten years later, we performed follow‐up investigations of the survivors (n = 48) who consented. Forty‐six fulfilled the revised Ghent criteria. Median age: females 51 years, range 32–80 years; males 45 years, range 30–67 years. New aortic root dilatation was detected in patients up to 70 years. Ascending aortic pathology was diagnosed in 93 versus 72% at baseline. Sixty‐five percent had undergone aortic surgery compared to 39% at baseline. Pulmonary trunk mean diameter had increased significantly compared to baseline. From inclusion to follow‐up, two patients (three eyes) developed ectopia lentis, four developed dural ectasia, four developed scoliosis, three developed incisional or recurrent herniae, and 14 developed hindfoot deformity. No changes were found regarding protrusio acetabuli, spontaneous pneumothorax, or striae atrophicae. The study confirms that knowledge of incidence and progression of organ manifestations throughout life is important for diagnosis, treatment, and follow‐up of patients with verified or suspected MFS.  相似文献   
7.
CONTEXT: Apoptosis occurs in the normal placenta. The monoclonal antibody M30 is directed against a novel epitope of cytokeratin 18 (CK18) that is formed by caspase cleavage early in the apoptotic cascade, and this antibody may therefore be useful for evaluating trophoblast apoptosis. OBJECTIVE: We undertook the present study to evaluate the use of monoclonal antibody M30 to assess trophoblast apoptosis in placenta at term. METHODS: We stained paraffin-embedded placental tissues from 15 deliveries at term with M30. We compared positive M30 staining and CK18 staining (as detected by a monoclonal antibody directed against CK18) of trophoblasts in serial slides. We also compared apoptotic rates as detected by M30 and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling) in 7 of the placentas. RESULTS: In fields of villous tissue, most M30-positive cells were CK18-positive syncytiotrophoblasts. Approximately half of M30-positive cells occurred as focal positive staining in the syncytial layer, and half occurred as abundant staining of syncytiotrophoblasts in areas with increased intervillous or perivillous fibrinoid. We found very few M30-positive cells in villous stroma. In decidual/basal plate tissues, most (two thirds) of the M30-positive cells were CK18-positive extravillous trophoblasts, whereas one third were syncytiotrophoblasts of anchoring villi. Since TUNEL detects apoptosis in both epithelial and nonepithelial cells, more cells were positively stained with TUNEL than with M30 in some tissue fields. However, our observations suggest that M30 was more sensitive than TUNEL in recognizing apoptotic trophoblasts and had less nonspecific staining than TUNEL. CONCLUSION: We recommend the use of monoclonal antibody M30 for apoptosis studies in placental tissues. This antibody is easy to handle, the staining obtained seems specific, and the nonspecific staining seems negligible.  相似文献   
8.
The effects of ECT on 5-hydroxyindoleacetic acid, homovanillic acid (HVA), and 4-hydroxy-3-methoxyphenylglycol in cerebrospinal fluid and on kinetic parameters of platelet serotonin uptake were studied in 12 patients with melancholia. There were no significant changes in the monoamine metabolites 3 weeks after initiation of ECT in 12 patients; however, there was a tendency for HVA to increase. The V(max) of serotonin uptake (measured in seven patients) remained unchanged after ECT, but there was a significant increase in K(m), indicating a decreased affinity for serotonin in the carrier.  相似文献   
9.
Understanding the forces underpinning female genital mutilation/ cutting (FGM/C) is a necessary first step to prevent the continuation of a practice that is associated with health complications and human rights violations. To this end, a systematic review of 21 studies was conducted. Based on this review, the authors reveal six key factors that underpin FGM/C: cultural tradition, sexual morals, marriageability, religion, health benefits, and male sexual enjoyment. There were four key factors perceived to hinder FGM/C: health consequences, it is not a religious requirement, it is illegal, and the host society discourse rejects FGM/C. The results show that FGM/C appears to be a tradition in transition.  相似文献   
10.
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