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   996篇
  免费   65篇
  国内免费   4篇
耳鼻咽喉   4篇
儿科学   26篇
妇产科学   24篇
基础医学   83篇
口腔科学   56篇
临床医学   62篇
内科学   187篇
皮肤病学   13篇
神经病学   86篇
特种医学   29篇
外科学   235篇
综合类   34篇
预防医学   99篇
眼科学   11篇
药学   70篇
中国医学   2篇
肿瘤学   44篇
  2023年   9篇
  2022年   34篇
  2021年   36篇
  2020年   25篇
  2019年   31篇
  2018年   40篇
  2017年   32篇
  2016年   25篇
  2015年   31篇
  2014年   57篇
  2013年   49篇
  2012年   70篇
  2011年   68篇
  2010年   46篇
  2009年   29篇
  2008年   46篇
  2007年   40篇
  2006年   40篇
  2005年   39篇
  2004年   35篇
  2003年   28篇
  2002年   28篇
  2001年   16篇
  2000年   14篇
  1999年   20篇
  1998年   7篇
  1997年   4篇
  1996年   6篇
  1995年   7篇
  1994年   5篇
  1993年   3篇
  1992年   8篇
  1991年   15篇
  1990年   5篇
  1989年   15篇
  1988年   6篇
  1987年   19篇
  1986年   8篇
  1985年   14篇
  1984年   8篇
  1982年   4篇
  1981年   6篇
  1980年   3篇
  1978年   4篇
  1971年   2篇
  1969年   2篇
  1968年   4篇
  1967年   2篇
  1966年   4篇
  1934年   2篇
排序方式: 共有1065条查询结果,搜索用时 15 毫秒
81.
82.
OBJECTIVES: On the basis of information from studies of older adults, smoking is considered to be an important risk factor for periodontal disease. Examining periodontal loss of attachment among younger adults means a lower contribution from cumulative exposure to other environmental risk factors. The aim of this study was to examine the role of chronic exposure to cigarette smoking as a risk factor for greater prevalence and extent of periodontal loss of attachment among 26-year-old participants in a longstanding prospective cohort study. METHODS: Loss of attachment (LOA) was measured at three sites per tooth in two randomly selected contralateral quadrants (one upper, one lower). Cigarette smoking history was obtained at ages 15, 18, 21 and 26, and used to categorise participants as "never-smokers", "ever-smokers", "long-term smokers" or "very longterm smokers". RESULTS: Periodontal data were available for 914 Study members, among whom the prevalence of LOA of 4+mm was 19.4%. Among those who smoked at ages 15, 18, 21 and 26, it was 33.6%, and, after controlling for sex, selfcare and dental visiting, they were nearly three times as likely to have one or more sites with 4+mm LOA. CONCLUSIONS: Chronic exposure to smoking is a strong predictor of periodontal disease prevalence in young adults.  相似文献   
83.
84.
Previous studies reported controversial results concerning alterations of astrocytes in schizophrenia. Because S100B may be regarded as a marker for astrocytes, the objective of this study was to examine S100B serum concentrations in 30 patients with schizophrenia with a monoclonal two-site immunoluminometric assay that specifically detects S100B. An ANOVA revealed medication (p<0.005) and deficit vs. nondeficit syndrome (p<0.05) as factors that influenced S100B significantly. S100B was higher in schizophrenic patients treated with antipsychotic drugs for approximately 3 weeks (241.1+/-152.5 ng/l) in comparison with unmedicated patients (111.4+/-31.8 ng/l, p<0.005), and healthy age-matched controls (112.8+/-53.4 ng/l, p<0.001; Bonferroni corrected two-tailed Student's t-test). There was no difference of S100B between unmedicated patients and controls (p>0.05). Patients with deficit (250.6+/-154.9 ng/l) had higher S100B levels than patients with nondeficit schizophrenia (146.7+/-107.2 ng/l, p<0.05) or controls (p<0.005). S100B was positively correlated with the subscore 'thought disturbance' of the Brief Psychiatric Rating Scale (p<0.05). In summary, increased serum levels of S100B may indicate alterations of astrocytes during early treatment with antipsychotics and in deficit schizophrenia. Whether S100B is elevated due to injured astrocytes and a disrupted blood-brain barrier, or by active secretion of S100B by astrocytes, has to be clarified by further studies.  相似文献   
85.
Endomyocardial injection of adenoviral gene vectors enables localized delivery to comprised myocardial tissue. However, many materials used in endomyocardial delivery catheters may not be compatible with adenoviral gene vectors. In this study, a series of catheter-based endocardial and epicardial (direct visualization) procedures were performed to assess catheter-adenovirus compatibility in an in vivo model. A standard Nitinol-stainless steel (Ni-SS) catheter was compared with a novel Stiletto catheter designed for improved biocompatibility. In 4 animals 40 endocardial injections of adenovirus encoding beta-galactosidase (beta-Gal) were performed with the 2 catheters. After sectioning of the hearts only 8 of 20 Ni-SS beta-Gal+ sites could be identified (40% retrieval) whereas 16 of the 20 Stiletto injection sites were identified (80%). Within these areas successful transfection was observed (12.2 +/- 4.0 beta-Gal+ cells/high-power field [HPF] in the Ni-SS group vs. 30.1 +/- 6.8 beta-Gal+ cells/HPF in the Stiletto group; p = 0.03). After epicardial delivery to distinct areas of the myocardium adenoviral delivery as assayed by beta-galactosidase protein activity was >21 +/- 16-fold (range, 5 to >43-fold) greater than after Stiletto delivery. In conclusion, this study highlights the importance of adenovirus-material compatibility in gene delivery to the myocardium. Efficiency was greater when using the catheter designed to enhance biocompatibility.  相似文献   
86.
OBJECTIVE: We assessed test meal intake in men and women with and without binge eating disorder (BED) in relation to mood score (Zung scale). METHODS: Eighty-five overweight subjects (24 males and 61 females) participated; 30 subjects with BED and 55 without BED. Following an 8-hr fast, subjects consumed a liquid test meal until extremely full. RESULTS: BED subjects consumed significantly more (p =.009) of the test meal (1,032 g +/- 429) than the non-binge eaters (737 g +/- 399). The men ingested more than the women (p =.002). BED subjects also had higher depression scores (p =.01), without differing by gender. However, depression scores were unrelated to test meal intakes (r = -.01). DISCUSSION: The larger meal intakes of the BED group may be due to the larger stomach capacity previously found in both bulimics and obese subjects. The findings also support the premise that BED, listed in the DSM-IV appendix for further study, is found in a distinct subgroup of overweight individuals.  相似文献   
87.
OBJECTIVE: To test the hypothesis that hyperinsulinemic obese subjects would respond differently to changes in the composition of hypoenergetic diets. DESIGN: A 4-week randomized dietary intervention trial. SUBJECTS: Thirteen male obese hyperinsulinemic normoglycemic subjects were divided into two groups and fed hypoenergetic diets providing 80% of their resting energy expenditure (REE). One group received a high-protein diet (HP; 45% protein, 25% carbohydrates, and 30% fat as percent of dietary energy) and the other a high-carbohydrate diet (HC; 12% protein, 58% carbohydrates and 30% fat). MEASUREMENTS: Anthropometry, body composition, fasting serum insulin and lipids, and REE were performed before and after the feeding period. RESULTS: Weight loss was higher in the HP than HC group (8.3+/-0.7 vs 6.0+/-0.6 kg, P<0. 05). There was a decrease in body fat in both groups, whereas body water decreased significantly more in the HP group. REE decreased more in the HC than the HP group (-384.3+/-84.6 vs -132.3+/-51.0 kcal, P<0.05). Serum total cholesterol, triglycerides and LDL cholesterol decreased significantly to a similar extent in both diet groups, while HDL cholesterol was decreased significantly only in the HP group. Mean fasting insulin decreased significantly in both diet groups and reached the normal range only in the HP group. CONCLUSION: A low-carbohydrate (LC), HP hypoenergetic diet could be the diet composition of choice for a weight-reducing regimen in obese hyperinsulinemic subjects.  相似文献   
88.
89.
90.
Chronic L-deprenyl-induced up-regulation of the dopamine uptake carrier   总被引:1,自引:0,他引:1  
L-Deprenyl is an inhibitor of monoamine oxidase B and dopamine uptake. Chronic L-deprenyl (10 mg/kg i.p., twice weekly for 4 weeks) was shown to inhibit monoamine oxidase B activity by 89%, and also to induce an up-regulation of the [3H]mazindol binding site associated with the striatal dopamine uptake carrier. Scatchard analysis indicated a 56% increase in the maximal number of [3H]mazindol binding sites in chronic L-deprenyl animals, but no effect on the affinity of these binding sites. The ability of L-deprenyl to up-regulate the [3H]mazindol-associated dopamine uptake carrier appears to be a result of its role as a dopamine uptake inhibitor.  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