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   3110篇
  免费   226篇
  国内免费   75篇
耳鼻咽喉   27篇
儿科学   48篇
妇产科学   49篇
基础医学   375篇
口腔科学   55篇
临床医学   201篇
内科学   604篇
皮肤病学   138篇
神经病学   145篇
特种医学   44篇
外科学   561篇
综合类   279篇
预防医学   175篇
眼科学   36篇
药学   301篇
中国医学   62篇
肿瘤学   311篇
  2024年   6篇
  2023年   54篇
  2022年   86篇
  2021年   136篇
  2020年   101篇
  2019年   219篇
  2018年   180篇
  2017年   115篇
  2016年   81篇
  2015年   93篇
  2014年   181篇
  2013年   166篇
  2012年   122篇
  2011年   180篇
  2010年   141篇
  2009年   165篇
  2008年   136篇
  2007年   142篇
  2006年   140篇
  2005年   108篇
  2004年   88篇
  2003年   93篇
  2002年   54篇
  2001年   63篇
  2000年   46篇
  1999年   35篇
  1998年   30篇
  1997年   28篇
  1996年   23篇
  1995年   23篇
  1994年   15篇
  1993年   9篇
  1992年   12篇
  1991年   12篇
  1988年   8篇
  1987年   8篇
  1986年   9篇
  1985年   22篇
  1984年   49篇
  1983年   29篇
  1982年   42篇
  1981年   30篇
  1980年   26篇
  1979年   22篇
  1978年   18篇
  1977年   6篇
  1976年   16篇
  1975年   17篇
  1974年   9篇
  1973年   7篇
排序方式: 共有3411条查询结果,搜索用时 15 毫秒
21.
Twenty miles per hour (mph) speed limits can impact the health of the public (e.g., road safety, active travel). However, a better understanding of how individuals experience 20mph limits is required, to ensure interventions are cognisant of perceptions and potential un/intended outcomes. Focus groups (n = 9, 60 participants) to explore the Belfast 20mph intervention highlighted divergent perspectives and experiences including: 12 mechanisms (e.g., limited awareness), 15 pathways (e.g., reduced driving speed→improved liveability) and 10 public health outcomes (e.g., increased cyclist safety). Future interventions should consider un/intended outcomes and implement strategies to enhance effectiveness and mitigate harms (e.g., through training, enforcement).  相似文献   
22.
弓形虫主要表膜P30抗原的免疫保护作用研究   总被引:2,自引:0,他引:2  
目的 研究弓形虫主要表膜P30抗原免疫小鼠所诱导的免疫性保护作用及免疫保护机制。方法 将单克隆抗体免疫亲和层析分离纯化的P30抗原免疫C57BL/6纯系小鼠,然后用弓形虫RH株速殖子和Fukaya株包衰攻击感染,观察P30抗原免疫对急性弓形虫感染鼠死亡时间及慢性感染鼠脑内包囊形成的影响,同时对感染后不同时间鼠血清特异性抗体水平、IL-2及IFN-r细胞因子水平和脾T淋巴细胞亚群动态变化进行了测试分析。结果 显示P30抗原免疫可在一定程度上延长感染小鼠的存活时间,减少脑内包囊的形成数量,增强小鼠抵抗急慢性弓形虫感染的能力。在感染后不同时期免疫鼠血清中特异性抗休还清瘃IFN-r、IL-2水平均高于同期对照鼠,而且免疫鼠脾CD4^ t CD8^ T淋纠细胞尤其是CD8^ 细胞的数量在感染早期升高较快,至感染后4周达高峰,两者的比值随感染时间的延长而逐渐下降。结论 P30抗原免疫对感染小鼠具有明显的保护作用,是细胞免疫和体液免疫共同作用的结果,尤其是细胞免疫可能发挥着更为重要的作用。  相似文献   
23.
目的构建弓形虫主要表面抗原P30基因的原核表达载体并在E.coli中进行表达.方法采用定向克隆的方法,将PCR扩增得到的P30片段,插入原核表达质粒pBV220上,转化大肠杆菌DH5α感受态细胞,于氨苄LB培养平板上筛选阳性克隆,经过酶切及PCR扩增鉴定重组子.将含阳性重组子pBV220-P30的工程菌经温度诱导表达,SDS-PAGE电泳及免疫印迹分析.结果成功构建了pBV2200-P300重组质粒;SDS-PAGE电泳及Western-blot显示表达P30非融合蛋白的分子量为29kD,且能被弓形虫高免鼠血清识别.结论从弓形虫基因组DNA中获取P30基因,并成功构建了pBV220-P30重组质粒,诱导表达了P30非融合蛋白.对弓形虫病基因疫苗研制奠定了基础.  相似文献   
24.
Hantavirus can cause panphilic infection in hu-man beings and proliferate especially in such impor-tantimmune organs and cells,as liver,spleen,bonemarrow,lymph nodes,thymus,lymphocyte and soon,thusresulting in immunity disturbance.CD30 is atransmembrane glycoprotein,belonging to the TNF/NGF receptor superfamily.In recent years,the bio-logical significance of CD30 elicited greatconcern.Theclose relationship between the expression of CD30antigen and theactivation and function of T cellssug-…  相似文献   
25.
26.
27.
28.
ObjectiveThis study aimed to evaluate the possible effects of surgical procedures on mortality and to identify the possible risk factors for mortality in the management of geriatric hip fractures.MethodsA total of 191 patients (105 women and 86 men; mean age 82.26±9.681 [60–108] years) with AO/OTA 31A2.2 intertrochanteric fractures and treated with sliding hip screw, proximal femoral nail, or hemiarthroplasty were included in this retrospective cohort study. The treatment type was decided by the responsible surgeon according to the patients’ pre-injury activity level, bone quality, and features of the fracture. Age, sex, type of fracture, type of surgery performed, American society of anesthesiology (ASA) grade, type of anesthesia, time to surgery, type of physical therapy, length of hospital stay, and number of comorbidities were documented. We evaluated the 30-day and 1-year mortality of patients treated with sliding hip screw (SHS), proximal femoral nail antirotation (PFN-A), or hemiarthroplasty and identified the possible risk factors for mortality.ResultsA total of 49 patients underwent SHS, 58 underwent PFN-A, and 84 underwent hemiarthroplasty. Of these, 2 patients with SHS, 2 with PFN-A, and 11 with hemiarthroplasty died within 30 days after surgery, whereas 7 patients with SHS, 15 with PFN-A, and 23 with hemiarthroplasty died 1 year after surgery. The 30-day and 1-year overall mortality rates were 7.9% and 23.6%, respectively. Both the 30-day and 1-year mortality risks were higher in patients undergoing hemiarthroplasty than in patients undergoing SHS (p=0.068 versus 0.058). The 30-day mortality was higher in patients receiving general anesthesia than in those receiving combined spinal and epidural anesthesia (p=0.009). The 1-year mortality risk was higher in patients with ASA grade 4 than in those with grade 1 and 2 (p=0.045). Advanced age (p=0.022) and male sex (p=0.007) were also found to be the risk factors for 1-year mortality.ConclusionWe demonstrated that higher ASA grade, male sex, general anesthesia, and hemiarthroplasty procedures are associated with higher mortality rates in elderly patients with hip fractures. Thus, we highly recommend orthopedic surgeons to consider all these factors in the management of intertrochanteric hip fractures in the geriatric population.Level of EvidenceLevel IV, Prognostic Study  相似文献   
29.
目的 制备抗弓形虫主要表膜P30抗原单克隆抗体(Mc-Ab)半进行鉴定,为弓形虫病的诊断、抗原的提纯及亚单位疫苗的研制等提供可靠依据。方法 用RH株弓形虫速殖子膜抗原为免疫BALB/C小鼠,取其脾细胞与小鼠SP2/0骨髓瘤细胞融合,筛选出能够稳定分泌高滴度抗P30抗原McAb杂交瘤细胞株,并测定Mc-Ab免疫球蛋白亚类和单抗效价,用IFAT进行单抗识别的抗原定们,并通过SDS-PAGE和Weste  相似文献   
30.
Echovirus 30 (E 30) outbreaks in defined cohorts have rarely been reported. In June 1996, an outbreak of E 30 occurred in four day-care centers (DCCs) in neighboring villages in Germany. A retrospective cohort study of DCC children, employees and household members was done to determine the extent of the outbreak and risk factors for illness. Forty-two percent (39/92) of DCC children, 13% (30/228) of their household members, 5% (1/19) of employees and 2% (1/49) of household members of employees were ill. Onsets occurred over 31 days. Thirteen percent (12/92) of DCC children had meningitis. In only one of 16 households with multiple family members ill, illness in a family member preceeded that of the DCC child. Household members of ill DCC children were 15 times more likely to report illness than those of non-ill DCC children. We conclude that this outbreak was associated with a very high incidence of meningitis, the outbreak began in the DCCs and then spread to household members, and that household members of ill children compared to those of non-ill children were much more likely to report illness.  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