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   377篇
  免费   26篇
  国内免费   18篇
耳鼻咽喉   7篇
儿科学   12篇
妇产科学   7篇
基础医学   33篇
口腔科学   20篇
临床医学   45篇
内科学   86篇
皮肤病学   9篇
神经病学   8篇
特种医学   49篇
外科学   23篇
综合类   12篇
预防医学   31篇
眼科学   5篇
药学   38篇
肿瘤学   36篇
  2023年   3篇
  2022年   7篇
  2021年   2篇
  2020年   5篇
  2019年   6篇
  2018年   6篇
  2017年   6篇
  2016年   4篇
  2015年   10篇
  2014年   6篇
  2013年   16篇
  2012年   12篇
  2011年   12篇
  2010年   22篇
  2009年   16篇
  2008年   11篇
  2007年   20篇
  2006年   13篇
  2005年   10篇
  2004年   11篇
  2003年   7篇
  2002年   3篇
  2001年   6篇
  2000年   5篇
  1999年   7篇
  1998年   15篇
  1997年   12篇
  1996年   17篇
  1995年   10篇
  1994年   14篇
  1993年   12篇
  1992年   2篇
  1991年   6篇
  1990年   5篇
  1989年   11篇
  1988年   10篇
  1987年   8篇
  1986年   14篇
  1985年   11篇
  1984年   7篇
  1983年   5篇
  1982年   8篇
  1981年   4篇
  1980年   3篇
  1978年   2篇
  1977年   4篇
  1976年   2篇
  1975年   4篇
  1968年   2篇
  1964年   1篇
排序方式: 共有421条查询结果,搜索用时 15 毫秒
71.
研究生一年级学生运动等级与其健康状况的相关性   总被引:2,自引:0,他引:2  
目的:调查研究生一年级学生的体育锻炼和健康状况,并分析其相关性。方法:调查于2005-09/10完成。选取西南大学和重庆大学2005级研究生一年级学生作为调查对象,共发放问卷190份,男90份,女100份。进行问卷调查,当场收回问卷。问卷内容:①自测健康评定量表:由48个条目构成,1~17为自测生理健康评定子量表(170~0分),19~34为自测心理健康子量表(150~0分),35~47为自测社会健康子量表(120~0分),分数越高代表越健康。②体育活动等级量表:主要调查调查对象上1个月参加体育锻炼的运动量,运动量=强度×时间×频率,强度与频率从1~5等级分别计1~5分,时间从1~5等级分别计0~4分,故运动量最高分为100分,最低分为0分。结果:有效回收176份问卷进入结果分析。①不同性别调查对象在运动等级上的分布情况:研究生一年级男女新生的运动量水平都偏低(男生:31.80±23.19,女生:15.57±15.39),且性别对运动量有显著的主效应(P<0.01),女生在运动量上的得分显著偏低。②调查对象健康状况各维度与运动量的相关性:运动量与总体健康、生理健康、心理健康和社会健康都存在显著相关性(r=0.150~0.238,P<0.05~0.01),生理健康对运动量有显著的预测作用(P<0.05)。③不同运动量等级调查对象的健康量表得分:运动等级对生理健康有显著的主效应(P<0.01),随着运动量的增加,研究生一年级学生的生理健康水平不断提高。结论:研究生一年级学生的体育锻炼运动量与健康水平存在着明显的正相关,随着运动量的增加,生理健康、心理健康及社会健康水平均不断增加。  相似文献   
72.
73.
Antifungal treatment options for allergic bronchopulmonary aspergillosis (ABPA) and severe asthma with fungal sensitisation (SAFS) are largely limited to itraconazole based on the outcome of randomised controlled trials. It is unclear if nebulised amphotericin B deoxycholate (Fungizone®) is a viable therapeutic option. We evaluated the safety and efficacy of nebulised Fungizone® in the long‐term treatment of various forms of pulmonary aspergillosis. We assessed the records of 177 patients with various forms of pulmonary aspergillosis attending the National Aspergillosis Centre in Manchester who had received Fungizone®. Patients first received a challenge test with nebulised Fungizone® in hospital with spirometry pre/post‐Fungizone® and nebulised salbutamol given pre‐Fungizone®. Tolerability and changes in Aspergillus IgE, Aspergillus IgG and total IgE were evaluated. Sixty‐six per cent (117/177) were able to tolerate the test dose of Fungizone® and in all cases, the reason for discontinuation of the first test dose was worsening breathlessness. Twenty six (21%) stopped therapy within 4‐6 weeks, and the commonest reason cited for discontinuation of therapy was increased breathlessness, hoarseness and cough. Eighteen (10.2%) patients continued the Fungizone® for >3 months of which 5 (27.8%) recorded an improvement in total IgE, Aspergillus‐specific IgE and Aspergillus IgG. Eleven had ABPA, four had SAFS, two had Aspergillus bronchitis and one had Aspergillus sensitisation with cavitating nodules. Among these 18 patients, sputum fungal culture results went from positive to negative in five patients, became positive in one patient, remained positive in three patients, and remained negative in seven patients. Nebulised Fungizone® appears to be a poorly tolerated treatment for pulmonary Aspergillosis with high dropout rates. There appears to be both clinical and serological benefits following sustained treatment with nebulised Fungizone® in some patients.  相似文献   
74.
目的:研究新的桂皮酰胺类衍生物,3-4二氯苯丙烯酰另丁胺(AED8801)对大鼠脑缺血/再灌注损伤的影响。方法:采用Pulsinelli四血管阻断大鼠脑缺血/再灌注模型,观察了AED8801对脑组织中水含量、氨基到含量、6-keto-PGF1α和TXB2含量,以及二者之比值的影响。结果:一AED8801能够降低脑缺血/再灌注大鼠所引起的脑水含量增加。二采用氨基酸自动分析仪进行检测,发现脑缺血/再灌  相似文献   
75.
猪脑钠素及其类似物的合成   总被引:1,自引:0,他引:1  
以固相多肽合成方法合成了猪的二十六肽脑钠素(BNP)和它的一个类似物(Mpr4,D-Ala6,13)-BNP(4-24)-NH2,保护肽用HF裂解除去保护基、在碱性条件下空气氧化形成二硫桥后,粗产物经凝胶过滤和高效液相色谱分离纯化,均有与天然脑钠素相同的活性。合成肽相对于树脂初始取代量的产率分别为9.56%和11.03%。  相似文献   
76.

Introduction

Phytoestrogens are a group of compounds found in plants that structurally resemble the hormone oestradiol, and thus have the potential to act as oestrogen agonists or antagonists. Their potential effects may alter the risk of breast cancer, but only a limited range of phytoestrogens has been examined in prospective cohort studies.

Methods

Serum and urine samples from 237 incident breast cancer cases and 952 control individuals (aged 45 to 75 years) in the European Prospective into Cancer-Norfolk cohort were analysed for seven phytoestrogens (daidzein, enterodiol, enterolactone, genistein, glycitein, o-desmethylangolensin, and equol) using liquid chromatography/mass spectrometry. Data on participants' diet, demographics, anthropometrics, and medical history were collected upon recruitment. All models were adjusted for weight, fat and energy intake, family history of breast cancer, social class, analytical batch, and factors related to oestrogen exposure.

Results

Urinary or serum phytoestrogens were not associated with protection from breast cancer in the European Prospective into Cancer-Norfolk cohort. Breast cancer risk was marginally increased with higher levels of total urinary isoflavones (odds ratio = 1.08 (95% confidence interval = 1.00 to 1.16), P = 0.055); among those with oestrogen receptor-positive tumours, the risk of breast cancer was increased with higher levels of urinary equol (odds ratio = 1.07 (95% confidence interval = 1.01 to 1.12), P = 0.013).

Conclusion

There was limited evidence of an association between phytoestrogen biomarkers and breast cancer risk in the present study. There was no indication of decreased likelihood of breast cancer with higher levels of phytoestrogen biomarkers, but the observation that some phytoestrogen biomarkers may be associated with greater risk of breast cancer warrants further study with greater statistical power.  相似文献   
77.

Introduction

The purpose of the present study was to investigate the effect of computer-aided detection (CAD) prompts on reader behaviour in a large sample of breast screening mammograms by analysing the relationship of the presence and size of prompts to the recall decision.

Methods

Local research ethics committee approval was obtained; informed consent was not required. Mammograms were obtained from women attending routine mammography at two breast screening centres in 1996. Films, previously double read, were re-read by a different reader using CAD. The study material included 315 cancer cases comprising all screen-detected cancer cases, all subsequent interval cancers and 861 normal cases randomly selected from 10,267 cases. Ground truth data were used to assess the efficacy of CAD prompting. Associations between prompt attributes and tumour features or reader recall decisions were assessed by chi-squared tests.

Results

There was a highly significant relationship between prompting and a decision to recall for cancer cases and for a random sample of normal cases (P < 0.001). Sixty-four per cent of all cases contained at least one CAD prompt. In cancer cases, larger prompts were more likely to be recalled (P = 0.02) for masses but there was no such association for calcifications (P = 0.9). In a random sample of 861 normal cases, larger prompts were more likely to be recalled (P = 0.02) for both mass and calcification prompts. Significant associations were observed with prompting and breast density (p = 0.009) for cancer cases but not for normal cases (P = 0.05).

Conclusions

For both normal cases and cancer cases, prompted mammograms were more likely to be recalled and the prompt size was also associated with a recall decision.  相似文献   
78.
Bagby  GC Jr; McCall  E; Bergstrom  KA; Burger  D 《Blood》1983,62(3):663-668
Human umbilical vein endothelial cells were cultured in supernatants of peripheral blood monocytes that had been cultured for 3 days with and without lactoferrin. Colony-stimulating activity (CSA) was measured in supernatants of the endothelial cell cultures and appropriate control cultures using normal, T-lymphocyte-depleted, phagocyte-depleted, low- density bone marrow cells in colony growth (CFU-GM) assays. Monocyte- conditioned medium contained a nondialyzable, heat labile factor that enhanced 4-15--fold the production of CSA by endothelial cells. The addition of lactoferrin to monocyte cultures reduced the activity of this monokine by 69%. Lactoferrin did not inhibit CSA production by monokine-stimulated endothelial cells. Therefore, vascular endothelial cells are potent sources of CSA, the production of CSA by these cells is regulated by a stimulatory monokine, and the production and/or release of the monokine is inhibited by lactoferrin, a neutrophil- derived putative feedback inhibitor of granulopoiesis. Inasmuch as a similar monokine is known to stimulate CSA production by fibroblasts and T lymphocytes, we suggest that mononuclear phagocytes play a pivotal role in the regulation of granulopoiesis by recruiting a variety of cell types to produce CSA.  相似文献   
79.
80.

Introduction

Mammographic density is known to be a strong risk factor for breast cancer. A particularly strong association with risk has been observed when density is measured using interactive threshold software. This, however, is a labour-intensive process for large-scale studies.

Methods

Our aim was to determine the performance of visually assessed percent breast density as an indicator of breast cancer risk. We compared the effect on risk of density as measured with the mediolateral oblique view only versus that estimated as the average density from the mediolateral oblique view and the craniocaudal view. Density was assessed using a visual analogue scale in 10,048 screening mammograms, including 311 breast cancer cases diagnosed at that screening episode or within the following 6 years.

Results

Where only the mediolateral oblique view was available, there was a modest effect of breast density on risk with an odds ratio for the 76% to 100% density relative to 0% to 25% of 1.51 (95% confidence interval 0.71 to 3.18). When two views were available, there was a considerably stronger association, with the corresponding odds ratio being 6.77 (95% confidence interval 2.75 to 16.67).

Conclusion

This indicates that a substantial amount of information on risk from percentage breast density is contained in the second view. It also suggests that visually assessed breast density has predictive potential for breast cancer risk comparable to that of density measured using the interactive threshold software when two views are available. This observation needs to be confirmed by studies applying the different measurement methods to the same individuals.  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