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   173537篇
  免费   11551篇
  国内免费   1320篇
耳鼻咽喉   2525篇
儿科学   3218篇
妇产科学   3912篇
基础医学   26216篇
口腔科学   3712篇
临床医学   16249篇
内科学   32797篇
皮肤病学   4767篇
神经病学   13056篇
特种医学   8870篇
外科学   23584篇
综合类   2228篇
现状与发展   5篇
一般理论   84篇
预防医学   10305篇
眼科学   4620篇
药学   14856篇
中国医学   1717篇
肿瘤学   13687篇
  2023年   831篇
  2022年   2273篇
  2021年   5249篇
  2020年   2700篇
  2019年   3904篇
  2018年   4762篇
  2017年   3530篇
  2016年   4561篇
  2015年   6171篇
  2014年   7583篇
  2013年   9127篇
  2012年   13747篇
  2011年   13376篇
  2010年   7866篇
  2009年   6643篇
  2008年   10039篇
  2007年   9843篇
  2006年   9040篇
  2005年   8553篇
  2004年   7621篇
  2003年   6621篇
  2002年   5781篇
  2001年   4730篇
  2000年   4327篇
  1999年   3523篇
  1998年   1422篇
  1997年   1072篇
  1996年   1012篇
  1995年   925篇
  1994年   793篇
  1993年   677篇
  1992年   1682篇
  1991年   1697篇
  1990年   1455篇
  1989年   1337篇
  1988年   1239篇
  1987年   1125篇
  1986年   1100篇
  1985年   964篇
  1984年   703篇
  1983年   618篇
  1982年   437篇
  1981年   412篇
  1980年   367篇
  1979年   567篇
  1978年   453篇
  1977年   430篇
  1976年   373篇
  1974年   388篇
  1973年   361篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
101.
102.
Background. It has been reported that gender differences in cardiovascular outcomes found in adults also are present in children who undergo surgical repair for congenital heart disease. Methods. California statewide hospital discharge data 1989–99 were used to study outcomes in children <18 years undergoing cardiac surgery. Hospital discharge data were linked to death registry data to study postdischarge death within 30 days of discharge. We used logistic regression to evaluate the effect of gender on mortality controlling for age, race and ethnicity, type of insurance, household income, date and month of surgery, type of admission, hospital case volume, and various types of procedures. Results. There were 25 402 cardiac surgery cases with 1505 in‐hospital deaths (mortality rate of 5.92%). An additional 37 deaths occurred within 30 days after hospital discharge. Crude mortality rates for males (5.99%) and females (5.84%) were not significantly different. However, fewer neonates were female and females underwent a higher proportion of low‐risk procedures than males. Logistic regression revealed that females, compared with males, had a significantly higher odds ratio (OR) for in‐hospital mortality (OR = 1.18, P < .01) and overall (up to 30 days post discharge) mortality (OR = 1.18, P < .01). The risk‐adjusted length of hospital stay was similar between females and males while charges per hospital day were slightly higher in females than males. The prevalence of Down syndrome, pulmonary hypertension, and failure to thrive were higher in females. Conclusions. Female gender is associated with an 18% higher in‐hospital and 30‐day postdischarge mortality as compared with male gender. There was no difference in length of hospital stay between males and females. The mechanism by which female gender acts as a risk factor requires further investigation.  相似文献   
103.
104.
105.
The clinical presentation of electrical injury commonly involves physical, cognitive, and emotional complaints. Neuropsychological studies, including case reports, have indicated that electrical injury (EI) survivors may experience a broad range of impaired neuropsychological functions, although this has not been clarified through controlled investigation. In this study, we describe the neuropsychological test findings in a series of 29 EI patients carefully screened and matched to a group of 29 demographically similar healthy electricians. Participants were matched by their estimated premorbid intellectual ability. Multivariate analysis of variance was used to assess group differences in the following neuropsychological domains: attention and mental speed, working memory, verbal memory, visual memory, and motor skills. EI patients performed significantly worse on composite measures of attention/mental speed and motor skills, which could not be explained by demographic differences, injury parameters, litigation status, or mood disturbance. Results suggest that cognitive changes do occur in patients suffering from electrical injury.  相似文献   
106.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
107.
Generally, a computed tomography scan is conducted for the diagnosis of stroke in the emergency department, because these scans are easier and faster in the detection of stroke. If there are no signs of hemorrhage on computed tomography scan, an ischemic stroke is diagnosed and treated accordingly. A magnetic resonance imaging scan may be taken in order to verify ischemic stroke. This process may lead to improper treatment and is time consuming. To address this situation, case studies are presented in which magnetic resonance imaging diffusion-weighted imaging and gradient recalled echo were performed to detect hemorrhagic and ischemic stroke and particularly, subarachnoid hemorrhage, which is undetectable with a computed tomography scan.  相似文献   
108.
The use of expanded criteria donors (ECD) has been proposed to help combat the discrepancy between organ availability and need. ECD kidneys are associated with delayed graft function (DGF) and worse long-term survival. The aim of this study is to evaluate the impact of pulsatile perfusion (PP) on DGF and graft survival in transplanted ECD kidneys. From January 2000 to December 2003, 4618 ECD kidney-alone transplants were reported to the United Network for Organ Sharing. PP was performed on 912 renal allografts. The prognostic factors of DGF were analyzed using multivariate logistic regression analysis. Risk factors for reduced allograft viability were greater in donors and recipients of PP kidneys. Three-year graft survival of ECD kidneys preserved with PP was similar to cold storage (CS) kidneys. The incidence of DGF in PP kidneys was significantly lower than CS kidneys (26% vs. 36%, p < 0.001). Despite having a greater number of risk factors for reduced graft viability, the ECD-PP kidneys had similar graft survival compared to ECD-CS kidneys. The use of PP, by decreasing the incidence of DGF, may possibly lead to lower overall costs and increased utilization of donor kidneys.  相似文献   
109.
110.
Targeted silencing of disease-associated genes by synthetic short interfering RNA (siRNA) holds considerable promise as a novel therapeutic strategy. However, unmodified siRNA can be potent triggers of the innate immune response, particularly when associated with delivery vehicles that facilitate intracellular uptake. This represents a significant barrier to the therapeutic development of siRNA due to toxicity and off-target gene effects associated with this inflammatory response. Here we show that immune stimulation by synthetic siRNA can be completely abrogated by selective incorporation of 2'-O-methyl (2'OMe) uridine or guanosine nucleosides into one strand of the siRNA duplex. These noninflammatory siRNA, containing less than 20% modified nucleotides, can be readily generated without disrupting their gene-silencing activity. We show that, coupled with an effective systemic delivery vehicle, 2'OMe-modified siRNA targeting apolipoprotein B (apoB) can mediate potent silencing of its target mRNA, causing significant decreases in serum apoB and cholesterol. This is achieved at therapeutically viable siRNA doses without cytokine induction, toxicity, or off-target effects associated with the use of unmodified siRNA. This approach to siRNA design and delivery should prove widely applicable and represents an important step in advancing synthetic siRNA into a broad range of therapeutic areas.  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