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   84330篇
  免费   7932篇
  国内免费   5419篇
耳鼻咽喉   616篇
儿科学   1017篇
妇产科学   1258篇
基础医学   10109篇
口腔科学   1626篇
临床医学   10688篇
内科学   13007篇
皮肤病学   882篇
神经病学   4522篇
特种医学   2982篇
外国民族医学   38篇
外科学   8150篇
综合类   13833篇
现状与发展   25篇
一般理论   13篇
预防医学   5731篇
眼科学   2144篇
药学   9097篇
  89篇
中国医学   4646篇
肿瘤学   7208篇
  2024年   359篇
  2023年   1380篇
  2022年   3408篇
  2021年   4286篇
  2020年   3286篇
  2019年   2739篇
  2018年   2954篇
  2017年   2676篇
  2016年   2485篇
  2015年   3788篇
  2014年   4647篇
  2013年   4329篇
  2012年   6449篇
  2011年   6801篇
  2010年   4404篇
  2009年   3466篇
  2008年   4619篇
  2007年   4459篇
  2006年   4062篇
  2005年   3948篇
  2004年   2849篇
  2003年   2584篇
  2002年   2335篇
  2001年   1883篇
  2000年   1964篇
  1999年   2052篇
  1998年   1308篇
  1997年   1294篇
  1996年   1018篇
  1995年   973篇
  1994年   799篇
  1993年   496篇
  1992年   579篇
  1991年   520篇
  1990年   438篇
  1989年   392篇
  1988年   306篇
  1987年   306篇
  1986年   237篇
  1985年   187篇
  1984年   123篇
  1983年   84篇
  1982年   62篇
  1981年   47篇
  1980年   33篇
  1979年   45篇
  1978年   18篇
  1974年   17篇
  1973年   17篇
  1966年   18篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
BACKGROUND: Moderate hypothermia is one of the effective therapeutic methods for head injury in recent years, there are many mechanisms of moderate hypothermia for brain protection, and its influence on cerebral oxygenation is also one of them. OBJECTIVE: To observe the influence of moderate hypothermia on cerebral oxygenation of animals with acute intracranial hypertension, and further investigate the protective mechanism of moderate hypothermia. DESIGN: A randomized controlled trial. SETTING: Department of Neurosurgery, Renji Hospital affiliated to the Medical College of Shanghai Jiao Tong University. MATERIALS: Twenty healthy little pigs, either male or female, weighing 4.5–5.5 kg, were used. Neurotrend-typed multiparameter monitoring system (Diametrics Company, British); CMA/100 micro-injection pump (Carnegie Company, Sweden). METHODS: The experiment was conducted in the Changzheng Hospital affiliated to the Second Military Medical University of Chinese PLA in November, 2001. The pigs were randomized into two groups: the normothermia group (control group, n =10) and moderate hypothermia group (n =10). ① Bilateral femoral arteries were separated, one was connected to pressometer for monitoring mean arterial pressure (MEP), and the other for analysis of blood gases [including peripheral blood pH value, arterial partial pressure of carbon dioxide (PaCO2), arterial partial pressure of carbon dioxide (PaCO2), HCO3–]. ② Rectal temperature was monitored with mercurial thermometer. ③ Intracranial pressure was monitored using Camino optic ICP probe placed in the subdural space. ④ Neurotrend multiparameter monitoring sensor was inserted into the white matter for about 4 cm to determine cerebral perfusion pressure (CPP, CPP=MAP(ICP), brain tissue partial oxygen pressure (PO2), partial pressure of carbon dioxide (PCO2), HCO3– and brain temperature. The rectal temperature of animals in the moderate hypothermia group was lowered to 34 ℃ using ice bags, and the body temperature was maintained at 33–35 ℃ for 2 hours. The changes of the parameters were observed continuously, and the pigs in the normothermia group were not treated with cooling. MAIN OUTCOME MEASURES: ① MAP, ICP, rectal temperature, CCP; Indexes of cerebral oxygenation detected with Neurotrend-typed multiparameter monitoring system; ② Results of blood gases analysis in the moderate hypothermia group. RESULTS: All the 20 pigs were involved in the analysis of results. ① MAP, ICP, rectal temperature, CCP and indexes of cerebral oxygenation: In the moderate hypothermia group, the ICP after cooling was obviously lower than that before cooling [(3.31±1.19), (5.33±0.95) kPa, P < 0.05], CCP was higher, brain tissue PCO2 [(12.03±1.73), (10.59±2.01) kPa, P < 0.05], and brain tissue pH value was higher [(7.03±1.63), (9.40±1.30) kPa, P < 0.05], whereas the brain temperature was decreased as compared with that before cooling [(34.9±0.3), (37.2±0.2) ℃, P < 0.05]. ② Results of blood gases analysis in the moderate hypothermia group: There were no significant differences in the parameters of peripheral arterial blood gases analysis before and after cooling in the moderate hypothermia group (P > 0.05) CONCLUSION: Moderate hypothermia will not impair the cerebral oxygenation, and it can reduce brain tissue CO2 and decrease brain tissue acidosis.  相似文献   
62.
The first universal hepatitis B vaccination program for newborns in the world was launched in Taiwan in July 1984. Most studies on the effectiveness of hepatitis B vaccination focused on the seroprevalence of HBs Ag among children under 14 years old. Only few studies focused on the seropositivity of anti-HBs among adolescents aged 15–18 years old. The present study aimed to evaluate the impact of the nationwide hepatitis B vaccination program on the immunity to HBV infection and the necessity of boost among adolescents. In this study including eight annual seroprevalence surveys from 2000 to 2007, 2342 college entrants (1589 15-year-olds in group I and 753 18-year-olds in group II) and 1851 university freshmen (18-year-olds in group III) participated. Subjects identified anti-HBs, HBs Ag and anti-HBc negative were given boost three doses of HBV vaccine. The HBs Ag seroprevalence was 11.6%, 3.5% and 1.0% for participants who were born before 1984, 1984–1986 and after 1986. The anti-HBs-seropositive rates were significantly higher in group II (83.1%) than in group I (53.0%) and group III (53.5%). All 572 participants who were seronegative for anti-HBs, HBs Ag and anti-HBc became anti-HBs-seropositive after catch-up vaccination. It is concluded that the anti-HBs-seropositive rate decreased to 50% in 15 years after vaccination, and boost vaccination was 100% effective. The necessity and age for boost among anti-HBs negative adolescents and the timing of the first immunization should be further evaluated.  相似文献   
63.
体育游戏是小学体育教学的重要内容,是教育学生最好的方法之一。我国现代著名教育家陈鹤琴先生说过:"小孩生来是好动的,是以游戏为生命的。"毛泽东同志在给《新体育》一书的题词中写道:"要活动,要游戏,是儿童的天性。"这充分说明了学生对游戏有着特殊的感情。  相似文献   
64.
Background: Malposition of percutaneously inserted chest tubes is considered as a rare complication in critically ill patients. Its incidence, however, remains uncertain. The aims of the study were to assess the true incidence of chest tube malposition in critically ill patients and to identify predicting factors.

Methods: The authors prospectively studied 122 chest tubes percutaneously inserted in 75 consecutive critically ill patients. For clinical reasons independent of the study, thoracic computed tomography scanning was performed in 63 patients, allowing direct visualization of 106 chest tubes. Based on these findings, chest tube position was classified as intrapleural, intrafissural, or intraparenchymal. Factors predicting chest tube malposition were analyzed by univariate and multivariate analysis.

Results: The mean delay between chest tube placement and thoracic scan was 3.5 +/- 2.9 days. Twenty-two chest tubes were diagnosed as being intrafissural (21%), and 10 were diagnosed as being intraparenchymal (9%). The only predicting factor associated with the risk of malposition was the use of a trocar for the percutaneous insertion of the chest tube (P = 0.032).  相似文献   

65.
目的 探讨性腺功能低减的青少年男性,短期雄激素替代治疗对血脂和超敏C反应蛋白(hsCRP)的影响。方法 本研究为前瞻性自身对照研究,共纳入33例性腺功能减退青少年男性。行短期(9个月)雄激素替代治疗,比较治疗前后血睾酮水平、第二性征发育程度、身高、握力、血红蛋白、血脂和hsCRP的差异。结果 (1)替代治疗后,睾酮水平明显升高,第二性征明显发育,身高、握力、血红蛋白显著增加(P值均〈0.05);(2)短期雄激素替代治疗后,总胆固醇(TC),低密度脂蛋白(LDL-c),高密度脂蛋白(HDL-c)和甘油三酯(TG)部有所下降,但无统计学差异(P〉0.5)。超敏CRP显著下降(P=0.025)。结论 (1)性腺功能低减的青少年男性,短期雄激素替代治疗,可以促进第二性征发育,增加身高、握力和血红蛋白;(2)短期雄激素替代治疗,对血脂无显著性影响。但是,可以使hsCRP明显下降。  相似文献   
66.
目的 :通过探讨梗阻性黄疸临床指征 ,了解其病程中的高危因素。并及时降低并发症及死亡率 ,提高临床疗效。方法 :对我科 1993年— 2 0 0 0年收治的 2 92例梗阻性黄疸病人进行性分析 ,统计年龄、梗阻时间、性质、手术时间 ,入院 2 4小时内测尿素氮 (BUN)、白蛋白 (A)、总胆红素(TBIL)、白细胞 (WBC)、血红素 (HB)、腹水 ,分析其高危因素。结果 :年龄 >6 5岁并发症发生率为2 5 .2 0 % ,病死率 3.2 5 % ;梗阻时间超过 2 0天以上者 ,并发症 2 8.87% ,病死率 5 .15 % ;肝功能Child氏B级、C级者 ,并发症发生率为 2 9.2 0 % ,病死率为 5 .31% ,延期手术并发症发生率为 2 9.4 1% ,病死率为 4 .90 %。结论 :梗阻性黄疸病人年龄越大 ,梗阻时间越长 ,肝功能越差 ,不及时手术是各种并发症发生及病死率增高的高危因素  相似文献   
67.
大鼠移植胰腺冷缺血再灌注后细胞凋亡的变化   总被引:2,自引:0,他引:2  
目的 探讨移植胰腺冷缺血再灌注后胰腺细胞凋亡的变化过程。方法  6 5只SD大鼠随机分成 7组 :假手术组 ,冷缺血 2h组 ,冷缺血 2h再灌注 1、3、6、9、12h组。通过HE染色后光镜及电镜观察各组的胰腺组织的病理变化 ;采用脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(TUNEL)检测凋亡细胞的分布及计数。结果 胰腺移植后早期即可观察到细胞凋亡的典型改变 ,胰腺冷缺血再灌注后发生凋亡的高峰期为再灌注后 3h[AI为 (9.4 6± 2 .91) % ,P <0 .0 1) ,再灌注 6h较 3小时细胞凋亡有所减少 [AI为 (5 .74± 1.6 6 ) % ,P <0 .0 1],再灌注 9h及 12h细胞凋亡进一步减少 [AI分别为 (3.6 0± 1.6 4 ) %及 (3.2 6± 1.35 ) % ,P <0 .0 5 ]。结论 细胞凋亡是胰腺移植后的早期事件 ,移植胰腺冷缺血再灌注后早期主要的死亡方式是凋亡 ;移植胰腺冷缺血再灌注后的凋亡高峰发生在再灌注后 3h。  相似文献   
68.
69.
N(G)-nitro-arginine (NNA) is known to exhibit stereoselective pharmacokinetics in which N(G)-nitro-d-arginine (d-NNA) has a faster clearance rate than N(G)-nitro-l-arginine (l-NNA) in anesthetized rats, and d-NNA undergoes unidirectional chiral inversion. It was postulated that chiral inversion of d-NNA was performed in a two-step pathway by d-amino acid oxidase (DAAO) followed by an unidentified transaminase. Such chiral inversion contributes (at least partially) to the pharmacokinetic stereoselectivity of NNA. This study used the selective inhibitor of DAAO, sodium benzoate, to test the above hypothesis. An i.v. bolus injection of d-NNA (32 mg/kg) and l-NNA (16 mg/kg) in conscious rats exhibited biphasic disposition with different pharmacokinetic parameters in a stereospecific manner (approximately 5-10-fold differences). Unidirectional chiral inversion of d-NNA but not l-NNA was found from these animals. In addition to its similar inhibitory effects on the d-NNA conversion and DAAO activity in kidney homogenates, sodium benzoate completely blocked chiral inversion of d-NNA and led to a smaller stereospecific difference, reflected by a nearly 50% reduction of d-NNA clearance and a 2-fold increase in t(1/2) and area under the curve of d-NNA in benzoate-pretreated rats. The results suggest that DAAO plays an essential role in chiral inversion of d-NNA and chiral inversion contributes mostly to the pharmacokinetic stereospecificity of NNA.  相似文献   
70.
目的 :观察氧雾化吸入备劳特和爱喘乐治疗儿童哮喘急性发作的疗效。方法 :选择 15 8例哮喘急性发作患儿作为研究对象 ,分为观察组和对照组。观察组采用氧驱动雾化吸入备劳特和爱喘乐 ;对照组静脉滴注氨茶碱和地塞米松。结果 :观察组显效率 87.3% (96 /110 ) ,总有效率 99.1% (10 9/110 ) ,临床治愈率 94 .5 % (10 4 /110 ) ;对照组显效率 2 2 .9% (11/48) ,总有效率 6 0 .4 % (2 9/48) ,临床治愈率 5 4 .2 % (2 6 /48)。观察组显效率、总有效率及临床治愈率皆显著高于对照组 ,差异有高度统计意义 (P <0 .0 1)。观察组治疗后心率较治疗前明显下降 ,差异有统计意义(P <0 .0 5 )。结论 :采用氧驱动雾化吸入备劳特和爱喘乐能快速、有效地控制哮喘发作。  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