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   2800篇
  免费   221篇
  国内免费   37篇
耳鼻咽喉   31篇
儿科学   167篇
妇产科学   44篇
基础医学   282篇
口腔科学   71篇
临床医学   327篇
内科学   579篇
皮肤病学   44篇
神经病学   224篇
特种医学   298篇
外科学   359篇
综合类   50篇
一般理论   1篇
预防医学   209篇
眼科学   45篇
药学   150篇
中国医学   3篇
肿瘤学   174篇
  2023年   15篇
  2022年   20篇
  2021年   59篇
  2020年   38篇
  2019年   41篇
  2018年   44篇
  2017年   49篇
  2016年   41篇
  2015年   55篇
  2014年   63篇
  2013年   89篇
  2012年   114篇
  2011年   120篇
  2010年   113篇
  2009年   107篇
  2008年   99篇
  2007年   110篇
  2006年   110篇
  2005年   127篇
  2004年   115篇
  2003年   73篇
  2002年   71篇
  2001年   76篇
  2000年   97篇
  1999年   83篇
  1998年   75篇
  1997年   58篇
  1996年   72篇
  1995年   52篇
  1994年   55篇
  1993年   55篇
  1992年   55篇
  1991年   52篇
  1990年   42篇
  1989年   57篇
  1988年   83篇
  1987年   54篇
  1986年   38篇
  1985年   52篇
  1984年   36篇
  1983年   39篇
  1982年   27篇
  1981年   18篇
  1980年   24篇
  1979年   23篇
  1978年   19篇
  1977年   15篇
  1976年   21篇
  1975年   13篇
  1974年   13篇
排序方式: 共有3058条查询结果,搜索用时 15 毫秒
41.
42.
BACKGROUND: The purpose of the present paper was (i) to identify trends in in-hospital mortality after transurethral resection of the prostate (TURP) in Victorian public hospitals; and (ii) to explore associations between in-hospital mortality after TURP and age, adverse events, type of admission (emergency/planned), location of the hospital (metropolitan/rural), teaching status of the hospital and length of stay. METHODS: Trends in in-hospital mortality after TURP and the associations between in-hospital mortality and the aforementioned variables were studied using International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) coded Victorian hospital morbidity data from public hospitals between 1987-88 and 1994-95. Crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) were based on univariate and multivariate logistic regression, respectively. RESULTS: After adjustment for age, comorbidity, and other confounding variables, the trend in mortality reduction over time was highly significant (P for trend < 0.0001, 95% CI for trend: 0.84-0.95). Highly significant associations with mortality were observed for emergency admissions (OR = 1.99, P < 0.0001), presence of adverse events (OR = 2.69, P < 0.0001), length of hospital stay (P for trend < 0.0001, 95% for trend: 1.88-2.15) and age (P for trend < 0.0001; 95% CI for trend: 1.26-1.48). CONCLUSIONS: Routinely collected data from hospitals can provide tentative evidence of improved effectiveness of a surgical treatment, provided analysis takes careful account of potential sources of bias, especially those related to possible changes in case selection over time. These kinds of data should stimulate a joint effort between clinicians, quality assurance experts and epidemiologists to confirm this attribution, and to locate the causative factors.  相似文献   
43.
44.
平贝碱乙的分离和鉴定   总被引:5,自引:0,他引:5  
本文报道了自东北平贝母(Fritillaria ussuriensis Maxim)中分得一种新的甾体生物碱,经光谱(IR,MS,1HNMR及13CNMR)解析和衍生物制备,推定其结构为5α,17β,22α-cevanine-3 β,6α,12α,14α,16β,20β-hexol,定名为平贝碱乙。  相似文献   
45.
抗CCT2单克隆抗体博来霉素A6偶联物可吸附胶体金颗粒(McAb-A6-Au)。电镜观察表明,在4℃,1h,表面有McAb-A6-Au颗粒的CEM细胞最高达78%;在37℃,4h,内化McAb-A6-Au颗粒的CEM细胞高达72%。而抗原性无关的U937细胞仅为14%。并且McAb-A6-Au颗粒能直接穿过细胞膜、核膜进入细胞浆和细胞核。37℃,1h已有10~18%的CEM细胞核内有McAb-A 6-Au颗粒。实验结果提示了单抗与博来霉素A6的偶联物与选择性地结合靶细胞,而且进入细胞速度快、穿透力强,有可能成为治疗白血病药物。  相似文献   
46.
47.
Both caffeine and the perception of refreshment delivered by cooling, tingling, and mouth-watering flavors have individually been shown to positively impact cognitive performance and mood, though presently there is limited evidence on their possible combined effects. This study explored the contribution of refreshing compounds in beverages, namely, carbon dioxide and citric acid, on the acute effects of caffeine on sustained attention and self-rated physical and mental energy. A randomized, controlled crossover trial was conducted by testing three products: a carbonated caffeinated beverage; a comparator caffeinated beverage; and a flavor-matched control beverage. Findings from 24 healthy adults revealed product-dependent variations in cognitive performance during a 60-min visual sustained-attention task, suggesting that the carbonated-caffeinated beverage led to faster, greater and more consistent levels of accuracy, compared to the control beverage. Specifically, significant differences were found between: (1) the carbonated-caffeinated beverage and the caffeinated beverage, and (2) between the caffeinated beverage and the control beverage for number of hits, reaction time and false alarm scores. Both caffeinated beverages led to higher physical and mental energy, and lower physical and mental fatigue 60-min post-consumption. These findings suggest beneficial effects on sustained attention through the combination of caffeine with refreshing compounds.  相似文献   
48.
49.
A case of monkeypox was diagnosed in a returning traveler from Nigeria to Maryland, USA. Prompt infection control measures led to no secondary cases in 40 exposed healthcare workers. Given the global health implications, public health systems should be aware of effective strategies to mitigate the potential spread of monkeypox.  相似文献   
50.
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