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   3518221篇
  免费   286448篇
  国内免费   15991篇
耳鼻咽喉   47564篇
儿科学   112062篇
妇产科学   91365篇
基础医学   558944篇
口腔科学   94239篇
临床医学   324115篇
内科学   619161篇
皮肤病学   90963篇
神经病学   302500篇
特种医学   135812篇
外国民族医学   392篇
外科学   531650篇
综合类   106509篇
现状与发展   23篇
一般理论   2324篇
预防医学   304222篇
眼科学   79556篇
药学   241165篇
  27篇
中国医学   10485篇
肿瘤学   167582篇
  2021年   55560篇
  2020年   35391篇
  2019年   58442篇
  2018年   72276篇
  2017年   55067篇
  2016年   60643篇
  2015年   74665篇
  2014年   108996篇
  2013年   174567篇
  2012年   100659篇
  2011年   101924篇
  2010年   119419篇
  2009年   122688篇
  2008年   87533篇
  2007年   91037篇
  2006年   101199篇
  2005年   96345篇
  2004年   97405篇
  2003年   87647篇
  2002年   77255篇
  2001年   107504篇
  2000年   100851篇
  1999年   99546篇
  1998年   65733篇
  1997年   63574篇
  1996年   61251篇
  1995年   56860篇
  1994年   51014篇
  1993年   47599篇
  1992年   70821篇
  1991年   67926篇
  1990年   64471篇
  1989年   62849篇
  1988年   58435篇
  1987年   57031篇
  1986年   54448篇
  1985年   54315篇
  1984年   49277篇
  1983年   44899篇
  1982年   42026篇
  1981年   39606篇
  1980年   37240篇
  1979年   40786篇
  1978年   35928篇
  1977年   32477篇
  1976年   30316篇
  1975年   28555篇
  1974年   30036篇
  1973年   28927篇
  1972年   27078篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
The Authors examine the correlation between hypertensive disorders of pregnancy and fetal growth. The results of a study of 342 pregnancies, confirm a significant correlation between hypertension and fetal growth retardation. These findings, so evident in moderate and severe hypertension, have also been confirmed in cases of mild hypertension. The medical treatment also in the pregnancies with mild hypertension, and a larger utilisation of operative deliveries, determined a decrease in perinatal mortality and morbidity.  相似文献   
993.
994.
Background The appearance of eosinophils is a hallmark sign of the allergic late-phase response (LPR). Eosinophil cationic protein (ECP), a readily measurable product released from activated eosinophils, has so far not been evaluated in the ocular LPR. Objective Two sets of trials were performed in order to investigate changes of local and systemic eosinophil activity and their possible link with symptoms and hyper-reactivity in the allergic LPR in the eye. Methods In the first experiment, ECP was analysed in tears and serum and the clinical reaction was evaluated during a 72-h time–course after a single, high-dose allergen challenge out of season in one eye of 15 pollen-sensitized volunteers. In a second experiment, the hypothesis of an increased clinical response to an allergen challenge in an eye that had been provoked with allergen 48h previously was tested in nine sensitized individuals. Results In the first experiment, symptoms at 10 min and 2, 4, 6, 8 and 24 h significantly exceeded base line scores of the challenged eyes. Tear ECP was significantly elevated in challenged eyes compared to contralateral eyes at 6, 8 and 24 h. In addition, symptoms and ECP release correlated significantly at the 24-h evaluation. Serum ECP remained unchanged throughout the study period. In the second experiment, conjunctival hyperreactivity 48h after an allergen challenge was not confirmed. Conclusion ECP secretion occurs in the experimental ocular LPR and is in part associated with the magnitude of the clinical reaction, which suggests a truly pathogenic role of the activated eosinophil in pollen-induced allergic conjunctivitis.  相似文献   
995.
996.
997.
998.
To determine whether fetal and infant growth could influencesusceptibility to autoimmune disease in adults, the occurrenceof thyroid autoantibodies and autoimmune thyroiditis was studiedin 305 women, aged 60–71, born in Hertfordshire and forwhom details of birth weight, infant growth, and feeding wereroutinely recorded. Thyroglobulin autoantibody was detectedin 37% of the women, thyroid peroxidase autoantibody in 41%,and autoimmune thyroiditis, defined as biochemical or clinicalhypothyroidism in association with thyroid autoantibodies, in5.6%. The proportion of women with thyroglobulin and thyroidperoxidase auto antibodies fell with increasing birth weightbut was not related to weight at 1 year of age or the methodof infant feeding. The prevalence of both autoantibodies rosewith increasing adult body mass index but fell as the waistto hip ratio increased. These results demonstrate the importance of early environmentin determining the susceptibility to autoimmune thyroid disease.The contrasting effects of adult body mass index and waist tohip ratio on antibody prevalence could be explained by theirassociations with different hormonal environments.  相似文献   
999.
The effects of daily oral administration of a high dose of 10 mg norethisterone acetate (NET-Ac.)/kg/day over 14 weeks on serum lipid and lipoprotein parameters as well as on blood coagulation were investigated in female monkeys (M. fascicularis). Measurements of lipids and lipoprotein cholesterol were performed in weeks —5 and — 1 before treatment and in weeks 4, 8 and 12 after treatment. In addition, various blood coagulation and fibrinolytic parameters were determined in weeks 11–14 after treatment with NET-Ac. Furthermore, the serum levels of norethisterone (NET) were determined in order to monitor the real systemic compound exposure and revealed that Cmax and AUC (0–3 h) values reached for norethisterone in this experiment in monkeys were about 25 times higher than those obtained after an oral contraceptive dose of NET-Ac. in women.

The results of lipid and lipoprotein cholesterol determinations showed decreases in serum total lipids, phospholipids, triglycerides and total cholesterol associated with similar decreases in HDL-, LDL- and VLDL-cholesterol fractions after NET-Ac.-treatment in monkeys. These effects were observed from week 4 onwards and maintained their magnitude up to week 12 after treatment. Since both HDL- and LDL-cholesterol fractions decreased, the HDL/LDL-ratio remained almost unchanged. Thus, the results obtained in this study after high-dose treatment with NET-Ac. in monkeys did not indicate any changes of lipid and lipoprotein parameters which in humans are supposed to be associated with an increased risk of cardiovascular lesions, namely a decrease in HDL- and increase in LDL-cholesterol fractions.

The results of blood coagulation and fibrinolytic parameters showed increased antithrombin-III and plasminogen levels besides minor changes in other parameters, thus indicating that NET-Ac. -treatment does not contribute to an increased risk of cardiovascular thrombotic events in the cynomolgus monkey.  相似文献   

1000.
Background : The clinical course of chronic hepatitis B is variable. Patients with hepatic decompensation, bridging necrosis or an alpha-fetoprotein level greater than 100 ng/mL during an exacerbation of hepatitis have a high risk of developing cirrhosis. This study was conducted to evaluate the effect of colchicine in the prevention of cirrhosis in such patients.
Methods : Patients with risk factor(s) were randomized to receive either colchicine 5 mg/week or no specific treatment, the end point being development of cirrhosis.
Results : After a follow up period of 4 years, the treatment group had a marked reduction in exacerbations of acute hepatitis (32% vs. 63%/patient/year, P <0.005). Seven out of 38 patients in the treatment group and 10 out of 27 patients in the control group developed cirrhosis. The calculated cumulative incidence of cirrhosis by the end of first, second, third and fourth years in the treatment group was 8.7, 18.6, 32 and 32%, respectively. The corresponding figures in the control group were 30, 35.5, 46.3 and 73.2%, respectively, with a P -value of 0.057.
Conclusions : The results suggest that colchicine may prevent cirrhosis in chronic hepatitis B patients with risk factor(s), possibly by suppressing exacerbations of hepatitis through an anti-inflammatory effect.  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