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   1595976篇
  免费   121601篇
  国内免费   3683篇
耳鼻咽喉   20789篇
儿科学   51955篇
妇产科学   44937篇
基础医学   227104篇
口腔科学   41969篇
临床医学   141057篇
内科学   323813篇
皮肤病学   38082篇
神经病学   133533篇
特种医学   59137篇
外国民族医学   553篇
外科学   233803篇
综合类   33537篇
现状与发展   3篇
一般理论   538篇
预防医学   127517篇
眼科学   35156篇
药学   111927篇
  1篇
中国医学   3917篇
肿瘤学   91932篇
  2021年   13703篇
  2019年   14811篇
  2018年   22497篇
  2017年   16545篇
  2016年   18177篇
  2015年   20330篇
  2014年   27088篇
  2013年   40713篇
  2012年   58421篇
  2011年   60939篇
  2010年   34603篇
  2009年   31816篇
  2008年   55597篇
  2007年   58905篇
  2006年   58493篇
  2005年   56849篇
  2004年   54087篇
  2003年   51154篇
  2002年   49085篇
  2001年   76743篇
  2000年   78439篇
  1999年   65034篇
  1998年   17657篇
  1997年   15983篇
  1996年   16119篇
  1995年   15271篇
  1994年   13812篇
  1993年   12961篇
  1992年   47976篇
  1991年   45385篇
  1990年   43335篇
  1989年   41256篇
  1988年   37864篇
  1987年   36910篇
  1986年   34389篇
  1985年   32654篇
  1984年   24861篇
  1983年   20922篇
  1982年   12728篇
  1981年   11201篇
  1979年   21611篇
  1978年   15234篇
  1977年   12723篇
  1976年   11871篇
  1975年   12263篇
  1974年   14785篇
  1973年   14350篇
  1972年   13382篇
  1971年   12191篇
  1970年   11594篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink.  相似文献   
23.
24.
The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.  相似文献   
25.
26.
The value of adding simeprevir (SMV) vs placebo (PBO) to peginterferon and ribavirin (PR) for treatment of chronic hepatitis C virus infection was examined using patient‐reported outcomes (PROs); further, concordance of PROs with virology endpoints and adverse events (AEs) was explored. Patients (= 768 SMV/PR,= 393 PBO/PR) rated fatigue (FSS), depressive symptoms (CES‐D) and functional impairment (WPAI: Hepatitis C Productivity, Daily Activity and Absenteeism) at baseline and throughout treatment in three randomised, double‐blind trials comparing the addition of SMV or PBO during initial 12 weeks of PR. PR was administered for 48 weeks (PBO group) and 24/48 weeks (SMV group) using a response‐guided therapy (RGT) approach. Mean PRO scores (except Absenteeism) worsened from baseline to Week 4 to the same extent in both groups but reverted after Week 24 for SMV/PR and only after Week 48 for PBO/PR. Accordingly, there was a significantly lower area under the curve (baseline–Week 60, AUC60) and fewer weeks with clinically important worsening of scores in the SMV/PR group at any time point. Incidences of patients with fatigue and anaemia AEs were similar in both groups, but FSS scores showed that clinically important increases in fatigue lasted a mean of 6.9 weeks longer with PBO/PR (P < 0.001). PRO score subgroup analysis indicated better outcomes for patients who met the criteria for RGT or achieved sustained virological response 12 weeks post‐treatment (SVR12); differences in mean PRO scores associated with fibrosis level were only observed with PBO/PR. Greater efficacy of SMV/PR enabled reduced treatment duration and reduced time with PR‐related AEs without adding to AE severity.  相似文献   
27.
28.
29.
30.
Children who expect they can bring about good outcomes and avoid bad outcomes tend to experience more personal successes. Little is known about factors that contribute to these ‘control expectancies’. The purpose of the present study was to determine whether children's internal control expectancies occur in the context of parents’ internal control expectancies, low family strain, and high family cohesiveness and whether these factors are more strongly related to daughters’ than sons’ control expectancies. A community sample of 85 children aged 9–11 years and their parents (85 mothers; 63 fathers) completed rating scales. Fathers’ more internal control expectancies and mothers’ reports of fewer family strains were associated with daughters’ but not sons’ greater internal control expectancies, and greater family cohesiveness was related to both daughters’ and sons’ internal control orientations. These findings suggest that family factors may contribute to children's, particularly daughters’, development of internal control expectancies.  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