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   90857篇
  免费   10593篇
  国内免费   4831篇
耳鼻咽喉   994篇
儿科学   1641篇
妇产科学   844篇
基础医学   5522篇
口腔科学   2029篇
临床医学   12050篇
内科学   9659篇
皮肤病学   1220篇
神经病学   2879篇
特种医学   3949篇
外国民族医学   4篇
外科学   8000篇
综合类   21580篇
现状与发展   13篇
预防医学   12112篇
眼科学   1202篇
药学   9470篇
  119篇
中国医学   8448篇
肿瘤学   4546篇
  2024年   488篇
  2023年   1430篇
  2022年   2775篇
  2021年   3560篇
  2020年   3274篇
  2019年   1763篇
  2018年   2226篇
  2017年   2794篇
  2016年   2307篇
  2015年   3860篇
  2014年   4796篇
  2013年   6224篇
  2012年   7712篇
  2011年   8065篇
  2010年   7399篇
  2009年   6767篇
  2008年   6516篇
  2007年   6258篇
  2006年   5514篇
  2005年   4375篇
  2004年   3090篇
  2003年   2572篇
  2002年   2072篇
  2001年   2003篇
  2000年   1393篇
  1999年   762篇
  1998年   469篇
  1997年   459篇
  1996年   457篇
  1995年   371篇
  1994年   326篇
  1993年   298篇
  1992年   290篇
  1991年   273篇
  1990年   271篇
  1989年   305篇
  1988年   259篇
  1987年   216篇
  1986年   223篇
  1985年   202篇
  1984年   174篇
  1983年   139篇
  1982年   103篇
  1981年   106篇
  1980年   86篇
  1979年   99篇
  1978年   96篇
  1977年   91篇
  1976年   77篇
  1972年   81篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The marine natural product, manoalide (MLD), was investigated to determine if this drug inhibited purified human synovial fluid phospholipase A2 (HSF-PLA2). Utilizing classical Michaelis-Menten kinetics, apparent Km and Vmax values for HSF-PLA2 of 1.34 mM and 0.47 mumol [3H]palmitic acid released/min/mg protein were obtained using dipalmitoylphosphatidylcholine (DPPC) as the substrate, and 38.0 microM and 18.8 mumol [3H]arachidonic acid released/min/mg protein with Escherichia coli as a natural substrate. These kinetic parameters were utilized subsequently to evaluate the inhibitory effects of manoalide on HSF-PLA2. Inhibition of HSF-PLA2 by MLD was concentration and time dependent with IC50 values of 0.2 and 0.02 microM for DPPC and E. coli respectively. Dialysis studies and examination of DPPC or E. coli hydrolysis versus enzyme concentration indicate that MLD is an irreversible inhibitor of HSF-PLA2. Substrate specificity was also examined in the absence and presence of MLD using dipalmitoylphosphatidylethanolamine (DPPE) as a substrate. MLD inhibited the hydrolysis of DPPE (greater than 90% inhibition at 2 microM), and preliminary results indicate that DPPC was more readily hydrolyzed than DPPE under the substrate conditions of the assay. While the cellular source of secreted HSF-PLA2 is unknown, these studies indicate that MLD can inactivate secreted phospholipase A2 isolated from patients with inflammatory joint disease.  相似文献   
82.
Mark R. Duncan  MD    W. Robert Kiser  MD  MA 《Headache》1996,36(6):397-397
  相似文献   
83.
84.
目的 探讨硫酸镁对SD大鼠局灶性脑缺血损伤的保护作用。方法 将 4 0只大鼠随机分成模型对照组、硫酸镁治疗组、亚低温治疗组、硫酸镁联合亚低温治疗组。采用线栓法建立大鼠局灶性脑缺血模型。通过计算大鼠神经功能缺陷评分 ,测量脑梗死体积 ,观察神经元超微结构改变 ,评定硫酸镁联合亚低温治疗作用。结果各治疗组大鼠神经功能评分及脑梗死体积均显著低于对照组 (P <0 0 5 ) ,联合治疗组大鼠明显低于对照组 (P<0 0 1) ;联合治疗组神经元超微结构改变轻微。结论 硫酸镁联合亚低温治疗对大鼠局灶脑缺血有明显保护作用  相似文献   
85.
This paper presents the results of a qualitative study conducted by midwife researchers into women's experience of new motherhood. Data were collected using focus groups involving 55 first-time mothers and analysed using grounded theory method. The analysis produced six categories: 'realizing', 'unready', 'drained', 'aloneness', 'loss' and 'working it out'. The core category, 'becoming a mother', integrates all other categories and encapsulates the process of change experienced by women. Also explained are factors mediating the often distressing experience of becoming a mother. The analysis provides a conceptualization of early motherhood enabling the development of strategies for midwives, nurses and others helping women negotiate this challenge.  相似文献   
86.
The history of antenatal education throws light on why contemporary class attenders represent only a particular section of the childbearing population. Since Victorian times, the non-availability of the women's network to middle class women has forced them to seek knowledge of their own bodies, confidence in their childbearing capacities and the support of other women through formal educational opportunities. Research suggests that antenatal classes often fail to provide women with a realistic account of birth and parenting to replace the lived experience of earlier decades and may not be facilitated in such a way as to create the support groups which class attenders critically need. Teaching approaches often promote dependency amongst clients rather than nurturing the decision-making skills required by a consumer-driven maternity service.  相似文献   
87.
Increased risk of pneumococcal infections in cardiac transplant recipients   总被引:3,自引:0,他引:3  
We observed 5 episodes of pneumococcal infection among 129 cardiac transplant patients between March 1985 and December 1987, giving an estimated incidence of 36 cases per 1000 patient-years. Infections occurred a mean of 58 days after transplantation and included bacteremia with empyema, bacteremia alone, and pneumonia. All patients recovered from their infections. There was no correlation between infection and age, sex, immunosuppression, or rejection episodes. We also measured antibody levels to 12 pneumococcal antigens in 6 unvaccinated, uninfected patients before and after cardiac transplantation, to see if baseline antibody levels decreased. Protective levels of antibody were defined as greater than or equal to 300 ng of anticapsular antibody nitrogen per milliliter serum. Before transplantation patients had protective antibody levels to a mean of 8.7 +/- 1.2 pneumococcal serotypes; after transplantation, the number of presumably protective antibody levels decreased to 6.5 +/- 1.4 (P = 0.021). One of these patients subsequently developed pneumococcal pneumonia. Cardiac transplant patients are at increased risk of pneumococcal infections. Vaccinating transplant candidates prior to transplantation may provide protection after transplantation.  相似文献   
88.
中药蝶脉灵注射液在心肺复苏中脑保护作用的实验研究   总被引:1,自引:0,他引:1  
目的 探讨中药蝶脉灵注射在心脏骤停时对脑复苏的作用。方法 用电刺激导致室颤制备家兔心脏骤停模型,在光镜和电镜下观察大剂量肾上腺素治疗时,蝶脉灵注射液对脑组织的影响。结果 蝶脉灵注射液对脑细胞有明显的保护作用。结论 蝶脉灵注射液能明显改善心脏骤停时脑缺血性损害,因而有利于脑复苏。  相似文献   
89.
踝部开放性骨折的急症手术治疗   总被引:5,自引:0,他引:5  
目的探讨踝部开放性骨折的损伤特点及相关的急症手术技术特点。方法2001年8月至2006年4月,急症手术治疗踝部开放性骨折51例,男39例,女12例;年龄18-72岁,平均36岁。伤口Gustilo分度,Ⅰ度3例,Ⅱ度37例,ⅢA度7例,ⅢB度3例,ⅢC度1例。急诊给予有效抗生素治疗,尽早开始手术。冲洗及彻底清创后,根据骨折类型、粉碎程度及伤口情况制定骨折处理的顺序,依次完成骨折复位、固定。结果48例患者获得随访,随访时间8-48个月,平均26个月。无一例发生深部感染。12例伤口发生浅表皮缘坏死,2例伤口延迟愈合,2例伤口发生浅表感染。踝部骨折在10-18周(平均13周)愈合。采用AOFAS踝后足功能评分标准,48例评分在76-100分,平均90分。结论踝部开放性骨折在急症手术时应彻底清创,注意保护皮肤活力。在处理后踝骨折时,可采用胫骨远端脱出法。多数手术应先精确复位、固定外踝骨折,对旋后内收型、外踝严重粉碎的踝部骨折应先进行内踝骨折的复位、固定。对严重的下胫腓联合分离,应直视下复位且常规使用下胫腓螺钉固定。  相似文献   
90.
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