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   3135792篇
  免费   267549篇
  国内免费   13879篇
耳鼻咽喉   43503篇
儿科学   96345篇
妇产科学   80992篇
基础医学   504614篇
口腔科学   86158篇
临床医学   279714篇
内科学   543295篇
皮肤病学   84842篇
神经病学   271708篇
特种医学   125164篇
外国民族医学   196篇
外科学   492515篇
综合类   101247篇
现状与发展   24篇
一般理论   2178篇
预防医学   265095篇
眼科学   71223篇
药学   215832篇
  22篇
中国医学   9108篇
肿瘤学   143445篇
  2021年   54509篇
  2020年   34767篇
  2019年   57634篇
  2018年   69899篇
  2017年   53234篇
  2016年   58765篇
  2015年   73193篇
  2014年   107268篇
  2013年   172252篇
  2012年   82866篇
  2011年   80761篇
  2010年   113178篇
  2009年   118811篇
  2008年   68092篇
  2007年   70304篇
  2006年   81565篇
  2005年   77226篇
  2004年   79773篇
  2003年   70993篇
  2002年   60641篇
  2001年   83969篇
  2000年   76137篇
  1999年   79981篇
  1998年   63060篇
  1997年   61527篇
  1996年   59265篇
  1995年   54810篇
  1994年   49144篇
  1993年   45972篇
  1992年   57335篇
  1991年   54592篇
  1990年   51799篇
  1989年   51380篇
  1988年   48157篇
  1987年   47068篇
  1986年   44877篇
  1985年   45470篇
  1984年   43536篇
  1983年   40209篇
  1982年   40250篇
  1981年   38094篇
  1980年   36020篇
  1979年   36874篇
  1978年   33505篇
  1977年   30827篇
  1976年   28035篇
  1975年   26559篇
  1974年   27677篇
  1973年   26597篇
  1972年   25034篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Pharmacokinetics of the cis-platin analog ethylenediaminemalonatoplatinum(II) (JM-410) was studied in 28 cycles of 19 patients during the phase I study of this drug. The drug was administered intravenously by short-term (10-60 min) infusion. Doses ranged from 20 to 1,200mg m-2. JM-40 was determined in plasma ultrafiltrate and urine by HPLC. Platinum (Pt) concentrations were determined in plasma, plasma ultrafiltrate, urine and red blood cells by atomic absorption spectrometry up to 5 days after administration of the drug. Ultrafilterable Pt could be determined up to 45 days after the infusion in one patient sampled over such a long period. Pharmacokinetics of JM-40 showed a linear behaviour. The final half-life of total Pt in plasma was 4.1 +/- 0.9 days. The disposition of JM-40 was similar to that of ultrafilterable Pt in respect to t1/2 alpha (10 and 13 min), t1/2 beta (44 and 57 min), volumes of distribution Vc (11 and 121) and Vss (17 and 201), systemic clearance (256 and 223 ml min-1), renal clearance (69 and 73 ml min-1) and metabolic clearance (183 and 154 ml min-1). During the first 6 h 27 +/- 9% of the administered dose was excreted as JM-40. Cumulative platinum excretion in the urine amounted to 29 +/- 13% and 60 +/- 13% over the first 6 h, 24 h and 5 days, respectively. The uptake of platinum in red blood cells was limited, comprising only 0.24 +/- 0.12% of the administered dose. Although JM-40 and carboplatin are structurally closely related, pharmocokinetics and toxicity of JM-40 were more similar to cis-platin than to carboplatin.  相似文献   
992.
Polymorphonuclear leukocyte (PMN) migration was assessed in vitro using the agarose plate method in patients with psoriasis vulgaris, and compared with an age- and sex-matched control group. No significant difference was found between the two groups in the PMN response to the chemotactic substances F-Met-Leu-Phe (FMLP) or zymosan activated serum (ZAS). Equally, the chemokinetic or chemotactic potential of psoriatic serum did not differ from control serum. Our results do not support a primary abnormality of PMN function in psoriasis.  相似文献   
993.
994.
Studies were performed in hypercholesterolemic rabbits to determine whether the hydrophobic surfactant, Poloxalene 2930 (Pol), is of benefit under these conditions. Lipoprotein analyses plus chemical and morphologic studies of the aorta were performed to evaluate the results. In one study, rabbits were made hypercholesterolemic by dietary means and then divided into two groups and given a cholesterol-free diet with one group additionally given Pol with treatment continued for 10 weeks. Pol treatment resulted in less atherosclerosis but the mechanism for this effect was not apparent from lipoprotein analysis. In the other study 3 groups of rabbits were given a cholesterol-rich diet for 16 weeks. Two groups received Pol supplement with one of these groups receiving a dose that was too small to prevent hypercholesterolemia. In this group plus the group on diet alone comparable degrees of hypercholesterolemia were maintained throughout the study. Lipoprotein abnormalities were similar in these two groups except that those on Pol had a more normal cholesterol to apolipoprotein B ratio. The amount of atherosclerosis in both groups was mild but aortic cholesterol content was much less for the Pol group. It is concluded that Pol limits cholesterol accumulation in the aortic wall of hypercholesterolemic rabbits and can retard the development of atherosclerosis.  相似文献   
995.
996.
997.
These researchers investigated the effects of a progressive resistive, cycle ergometric exercise program on cardio-vascular endurance in one rheumatoid arthritic. The 46 yr. old, male subject exercised three days/week for 14 weeks. Workouts included interval-type training using 5 minute intervals for a total of 20-30 minutes (work rate set at 50-75 watts for each interval), not including 3-minute warm-up and cool-down periods (work rate set at zero resistance). Maximal exercise stress testing on the cycle ergometer was completed and blood samples collected before and after the exercise program. Also, psychological and physical health and lifestyle data were gathered before, during and after completion of the program. The conditioning program produced a training effect (greater than 75% of the HR max after the second exercise session) and blood values improved (10-28%) from the beginning to the end of the program. Finally, the program appeared to have a positive influence on various physical and psychological parameters as perceived by the subject and his wife.  相似文献   
998.
Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial-nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty-four black-crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late-stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p less than 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown-rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8-52.0 ppm. A negative correlation (r = -0.61; p less than 0.05) existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth. A correlation with embryonic weight did not occur for DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] residues. Liver microsomal aryl hydrocarbon hydroxylase activity was neither significantly elevated nor correlated with PCB, DDE, or PCB plus DDE log-transformed residues. It is unknown whether the apparent association between PCBs and lower weight is persistent through hatching.  相似文献   
999.
1000.
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