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   1262篇
  免费   75篇
  国内免费   20篇
耳鼻咽喉   4篇
儿科学   33篇
妇产科学   15篇
基础医学   99篇
口腔科学   53篇
临床医学   169篇
内科学   204篇
皮肤病学   4篇
神经病学   93篇
特种医学   174篇
外科学   73篇
综合类   30篇
预防医学   268篇
药学   57篇
肿瘤学   81篇
  2023年   8篇
  2022年   4篇
  2021年   14篇
  2020年   4篇
  2019年   8篇
  2018年   9篇
  2017年   13篇
  2016年   11篇
  2015年   8篇
  2014年   24篇
  2013年   44篇
  2012年   28篇
  2011年   42篇
  2010年   32篇
  2009年   62篇
  2008年   41篇
  2007年   49篇
  2006年   44篇
  2005年   43篇
  2004年   38篇
  2003年   43篇
  2002年   37篇
  2001年   45篇
  2000年   48篇
  1999年   38篇
  1998年   60篇
  1997年   58篇
  1996年   57篇
  1995年   54篇
  1994年   33篇
  1993年   36篇
  1992年   16篇
  1991年   17篇
  1990年   20篇
  1989年   33篇
  1988年   26篇
  1987年   20篇
  1986年   12篇
  1985年   26篇
  1984年   17篇
  1983年   15篇
  1982年   21篇
  1981年   16篇
  1980年   18篇
  1978年   10篇
  1977年   12篇
  1976年   12篇
  1969年   4篇
  1968年   3篇
  1966年   3篇
排序方式: 共有1357条查询结果,搜索用时 15 毫秒
1.
Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case–control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD = 0.77, 95% confidence interval 0.66–0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD = 0.72, 0.57–0.90), or lysophosphatidylcholines (OR1SD = 0.81, 0.69–0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow-up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD = 0.77, 0.61–0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer.  相似文献   
2.
3.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
4.
Hysterosalpingography was performed in 31 patients by means of a low-dose scanning-beam digital radiographic system. The technique permits adequate evaluation of gynecologic abnormalities while allowing significant reduction in radiation: 2.4-mR (6.1 X 10(-7) C/kg) exposure to the skin and 0.7-mrad (7 X 10(-6) Gy) mean dose to the ovaries per image obtained. Sixteen patients demonstrated readily recognizable and documented abnormalities, corroborated by laparoscopy, laparotomy, or other supportive evidence.  相似文献   
5.
BACKGROUND: Merkel cell carcinoma is a rare malignant neuroendocrine neoplasm characteristically arising from the dermis of sunlight-exposed skin. It rarely arises outside the skin. OBJECTIVE: We present a patient with primary Merkel cell carcinoma arising from subcutaneous fat, with no involvement of the overlying skin. We describe the clinical manifestations and magnetic resonance imaging (MRI) findings. METHODS: We report a 63-year-old woman with a primary lesion of Merkel cell carcinoma that arose from the subcutaneous fat layer of the left arm. The lesion presented as a subcutaneous nodule with intact overlying skin. MRI showed that the nodular lesion was located entirely in the subcutaneous fat layer, with no involvement of the dermis. Peritumoral infiltration around the lesion and enlarged lymph nodes deep to the lesion were noted. The patient received wide excision of the lesion with dissection of the regional lymph nodes and adjuvant radiotherapy and chemotherapy. RESULTS: Histopathologic examination confirmed the diagnosis of Merkel cell carcinoma with local lymphatic metastasis, and the lesion was completely located in the subcutaneous fat, with no involvement of the dermis. These findings were well correlated with MRI findings. CONCLUSION: Primary Merkel cell carcinoma may arise from the subcutaneous fat and present as an entirely subcutaneous lesion with intact skin. MRI is helpful to evaluate the local extension of the lesion and regional lymphatic metastasis.  相似文献   
6.
表小檗碱对α受体的作用   总被引:2,自引:0,他引:2  
王嘉陵  方达超 《药学学报》1990,25(4):289-292
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择  相似文献   
7.
The purpose of this pilot study was to observe both relaxed and deep breathing patterns in a convenience sample to determine the incidence of normal versus faulty patterns of respiration. These observations were then combined with respondent answers to a survey on pain history to determine if there is any correlation between faulty breathing and musculo-skeletal pain patterns. If such a correlation can be made, then we propose that clinicians working with chronic pain patients may have improved outcomes if they address and correct faulty breathing patterns. Based on this study, it is suggested to include the evaluation and treatment of faulty respiration in the rehabilitation of chronic musculo-skeletal conditions, most notably cervical pain.  相似文献   
8.
36例踝关节骨折合并下胫腓联合分离的治疗体会   总被引:1,自引:1,他引:0  
李得春 《医学争鸣》2005,26(17):1631-1631
0 引言 踝关节骨折是临床上较常见的关节内骨折,包含了腓骨骨折,内踝骨折,后踝骨折和下胫腓联合的损伤. 处理不当可导致踝穴的变形,下胫腓联合分离后期出现创伤性关节炎.  相似文献   
9.
Patients who have had ileogastrostomy for the treatment of morbid obesity require close, long-term follow-up. From a prospective study of a large number of variables in 12 consecutive patients, and from experience with more than 200 patients who have undergone this procedure since 1982, a protocol has evolved. The authors outline the associated morbid conditions, operative complications and biochemical alterations that are important in the management of these patients.  相似文献   
10.
AIMS: To compare the performance of a new chromogenic medium, Uriselect 4, with cystine lactose electrolyte deficient (CLED) agar and an established chromogenic agar, CPS ID 2 medium, for detection of urinary tract pathogens. METHODS: Using a semiquantitative culture method, 777 samples were inoculated on to the three test media in duplicate. All bacterial strains that yielded a potentially significant growth were observed for colony colour and identified using standard methods. RESULTS: Of the 777 samples tested, 589 urine samples yielded potentially significant growth of at least one strain. A total of 811 strains were isolated on at least one of the three media. A total of 168 urine samples yielded a mixture of at least two strains. Uriselect 4 medium showed the best sensitivity of the three media and only failed to recover 14 strains (1.7%). CPS ID 2 medium failed to recover 22 strains (2.7%). CLED medium showed the worst recovery and failed to recover 74 strains (9.1%). Both chromogenic media allowed for identification of Escherichia coli with a high degree of specificity (98% for Uriselect 4, 99.7% for CPS ID 2). Inclusion of a spot indole test increased the specificity of both chromogenic media to 100% for E coli. CONCLUSIONS: Uriselect 4 and CPS ID 2 were superior to CLED medium for the isolation of urinary tract pathogens mainly because of their ability to discriminate mixed cultures. Both chromogenic media were also useful for the preliminary identification of the most common urinary tract pathogens.  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