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   1393264篇
  免费   100597篇
  国内免费   2472篇
耳鼻咽喉   19472篇
儿科学   45774篇
妇产科学   39806篇
基础医学   202611篇
口腔科学   37712篇
临床医学   120029篇
内科学   275403篇
皮肤病学   27871篇
神经病学   110500篇
特种医学   53556篇
外国民族医学   370篇
外科学   214134篇
综合类   28154篇
现状与发展   2篇
一般理论   460篇
预防医学   103433篇
眼科学   32044篇
药学   106122篇
  2篇
中国医学   2725篇
肿瘤学   76153篇
  2018年   14413篇
  2017年   10844篇
  2016年   12245篇
  2015年   14136篇
  2014年   19621篇
  2013年   29552篇
  2012年   41396篇
  2011年   44319篇
  2010年   25862篇
  2009年   24337篇
  2008年   42418篇
  2007年   45798篇
  2006年   45933篇
  2005年   45246篇
  2004年   43489篇
  2003年   41884篇
  2002年   41204篇
  2001年   59400篇
  2000年   60584篇
  1999年   51930篇
  1998年   15612篇
  1997年   13951篇
  1996年   13980篇
  1995年   13283篇
  1994年   12553篇
  1993年   11615篇
  1992年   41725篇
  1991年   41052篇
  1990年   40504篇
  1989年   39278篇
  1988年   36674篇
  1987年   35894篇
  1986年   34231篇
  1985年   32702篇
  1984年   24534篇
  1983年   21384篇
  1982年   13091篇
  1981年   11556篇
  1979年   23067篇
  1978年   16289篇
  1977年   14124篇
  1976年   13308篇
  1975年   14507篇
  1974年   17002篇
  1973年   16383篇
  1972年   15573篇
  1971年   14411篇
  1970年   13391篇
  1969年   12901篇
  1968年   12136篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
81.
82.
Multiple trauma is often associated with blunt thoracic injuries. Especially lung contusion can result in respiratory insufficiency and therefore a higher mortality rate. In our prospective study comparing 8 multiple trauma patients with and without associated lung contusion, we found that respiratory function was already significantly disturbed (decrease of paO2/FiO2 and increase of AaDO2, a rise in extravascular lung water (EVLW) both early after trauma and also with a second peak following the 4th day. This group (LK) developed significantly more cases of respiratory distress (ARDS). The disturbance of respiratory function seen initially was interpreted as a consequence of the direct mechanical impact, leading to the formation of interstitial fluid and hematoma. The frequent development of ARDS in the LK-group probably results from a pronounced activation of cellular and humoral mechanisms and therefore an enforced injury of the pulmonary capillary bed. A significant increase of pulmonary infections or the development of sepsis was not seen in the LK-group and is probably not responsible for the higher ARDS-rate in this group.  相似文献   
83.
84.
85.
Concanavalin A-induced lymphocyte proliferation was studied in 25 patients with alcoholic hepatitis or compensated alcoholic cirrhosis. Nine alcoholics without evidence of liver disease were also evaluated. A nonlinear correlation equation, which was natural logarithmic, was applied to individual dose-response proliferation curves and permitted comparisons between patient groups and controls. The proliferative response in all patient groups was significantly lower when compared to healthy controls and was independent of the presence or absence of liver disease. This suggests that some changes in immune function observed in alcoholics may be linked to the direct effects of alcohol on the immune system rather than to the associated liver disease.  相似文献   
86.
Macrophage NRAMP1 and its role in resistance to microbial infections   总被引:12,自引:0,他引:12  
  相似文献   
87.
Membrane-bound CD14 acts as a receptor for lipopolysaccharide (LPS) on monocytes/macrophages and neutrophils. Studies have suggested that the activation of monocytes/macrophages by the binding of LPS to membrane-bound CD14 may require the association of a signal-transducing molecule with membrane-bound CD14. The observation that non-CD14 expressing cells, such as endothelial cells, can nevertheless be activated by a complex of LPS and a soluble form of CD14 (sCD14) suggests that the receptor for this complex may be identical to the signal transducing molecule associated with membrane-bound CD14. The studies described show that two CD14-specific MoAb are able to block the LPS-induced activation of endothelial cells but do not affect the response of monocytes to LPS. This suggests that the interaction of the sCD14:LPS complex with endothelial cells is distinct from the interaction of membrane-bound CD14 with its putative signal-transducing molecule.  相似文献   
88.
Young adult female mice were injected with lead acetate (d 0). Following injection, determinations were made of the percentages of radioactive iron (59Fe) uptake into the hemoglobin of erythrocytes produced by spleen. Control 59Fe uptake percentage vacillated between 4.2 and 5.5 within the 7-d period of observation. On d 4 following lead treatment, splenic percentages were dramatically reduced below those of the saline-injected controls; by d 6 the splenic 59Fe uptake of lead-treated mice was comparable to that of controls. For rodents injected with cadmium chloride on 0, the 59Fe uptake values showed a statistically significant elevation by d 2, which was extended beyond that of the controls' d 4 value. For those animals receiving both lead and cadmium (d 0), the uptake percentages paralleled those of the controls throughout the 7-d period of observation. These data suggest that the inhibitory effect of lead on erythropoiesis of the spleen is blocked by a concurrent cadmium treatment. Results are interpreted in regard to a possible vulnerable target and competition for the target by lead and cadmium.  相似文献   
89.
Piecewise constant incidence models were developed to estimate the force of infection in women from age-and time-specific antenatal or neonatal seroprevalence data. Differential inclusion of infected women in sero-surveys compared to uninfected women was taken into account, with respect to both changes in inclusion rate following infection, and changes in relative inclusion rate over calendar time. These models were applied to anonymous HIV seroprevalence data collected from neonates born to black and Hispanic women in New York City 1988-1992, with incidence and fertility parameters estimated by maximum likelihood. Estimates of inclusion rate parameters accorded well with what is known about the natural history of HIV. The data could not distinguish between additive and multiplicative combination of the effects of age and time on incidence. Incidence was strongly dependent on age with the highest incidence in women aged 20-34 years. There was strong evidence that incidence had been falling in Hispanic women since 1982-1984. The results illustrate the extent to which trends in incidence over time may be confounded by changes in the relative inclusion rate of infected and uninfected women.  相似文献   
90.
The recently developed ELISA for the thrombin-antithrombin III complex (TAT) is a sensitive, specific, and simplified means of detecting intravascular coagulation. For further evaluation of the thrombogenicity of a polyamide (P) and a Hemophan (H) hollow-fibre dialyzer a cross-over study was done in ten stable patients on maintenance hemodialysis. At the same doses of heparin (mean bolus of 30 U/kg bw and maintenance doses of 86 U/kg bw), thrombin time and partial thromboplastin time were significantly lower using H. At the end of dialysis TAT was significantly higher in H (mean +/- SEM before HD 3.57 +/- .56, at 240 min 14.9 +/- 6.5 ng/ml, p less than 0.05, Wilcoxon-test) than in P (before HD 4.36 +/- .98, at 240 min 8.95 +/- 3.0 ng/ml, p less than 0.05 H 240 vs. P 240, Wilcoxon-test). Visible clotting was more pronounced in the H filter. Among other favourable features of blood compatibility the polyamide/polyvinylpyrrolidone copolymer with a hydrophilic/hydrophobic microdomain structure has less thrombogenicity. The modified cellulosic membrane H has advantages in complement activation and leukocyte depression, but thrombogenicity seems less favourable since the incorporated diethyl-amino-ethyl groups with their positive charge bind and inactivate negatively charged heparin.  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