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   977130篇
  免费   69566篇
  国内免费   1522篇
耳鼻咽喉   13346篇
儿科学   25818篇
妇产科学   24376篇
基础医学   139129篇
口腔科学   28849篇
临床医学   85480篇
内科学   192693篇
皮肤病学   20093篇
神经病学   77651篇
特种医学   37873篇
外国民族医学   79篇
外科学   156026篇
综合类   18409篇
现状与发展   1篇
一般理论   291篇
预防医学   67208篇
眼科学   21917篇
药学   75415篇
  27篇
中国医学   2246篇
肿瘤学   61291篇
  2021年   7798篇
  2019年   7594篇
  2018年   10882篇
  2017年   8316篇
  2016年   9202篇
  2015年   10435篇
  2014年   13904篇
  2013年   19985篇
  2012年   28045篇
  2011年   28951篇
  2010年   16794篇
  2009年   16007篇
  2008年   27391篇
  2007年   28453篇
  2006年   29121篇
  2005年   27870篇
  2004年   26729篇
  2003年   25529篇
  2002年   24784篇
  2001年   54907篇
  2000年   56676篇
  1999年   47149篇
  1998年   11062篇
  1997年   9713篇
  1996年   9796篇
  1995年   9092篇
  1994年   8400篇
  1993年   7708篇
  1992年   35548篇
  1991年   33974篇
  1990年   32788篇
  1989年   31924篇
  1988年   29041篇
  1987年   28286篇
  1986年   26325篇
  1985年   25177篇
  1984年   17879篇
  1983年   15186篇
  1982年   7828篇
  1979年   15798篇
  1978年   10611篇
  1977年   9072篇
  1976年   7878篇
  1975年   8636篇
  1974年   10471篇
  1973年   9866篇
  1972年   9360篇
  1971年   8857篇
  1970年   8427篇
  1969年   7926篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
We report herein a rare case of a 26 year old woman with pheochromocytoma complicated by paralytic ileus. She presented with remarkable abdominal distension and respiratory difficulty but was effectively treated by surgical removal of the tumor with preoperative and operative management using alpha and beta adrenergic blocking agents. An excessive and persistent catecholamine production from large tumors or massive metastases characterizes this rare complication, and a review of the English and Japanese literature is given following this report.  相似文献   
992.
993.
T Wu 《中华医学杂志》1990,70(2):72-6, 6
At extreme altitude of 5,620 m, cardiac function was examined with electrical impedance at rest and during exercise. Mountaineers as subjects of experiment were divided into two groups: 15 subjects were Tibetan natives, and 10 subjects were Han visitors of expedition (both were young healthy males). The results showed that no significant difference was seen between the two groups in cardiac pump function at rest. In the Han visitors during exercise, HR increase was restricted, SV and CO were decreased, and PEP/LVET ratio was increased. In the Tibetan natives, HR increased gradually with increased work load, SV tended to be stable CO increased significantly under higher work load, and PEP/LVET ratio decreased gradually. These results suggest that the Tibetan natives were adapted to hypoxic environment much better than the immigrants because their cardiac reserve capacity and maximal oxygen uptake were better than the immigrants at extreme altitude.  相似文献   
994.
Lipoprotein [a] (Lp[a]) is known to show high values in patients with ischemic heart disease (IHD). In the present study attempts were made to determine Lp[a] levels and to investigate the association of Lp[a] and other atherosclerotic risk factors in patients with chronic renal failure treated by hemodialysis. Lp[a] concentrations were measured in 30 hemodialysis patients in the age range 34 to 77 years. Mean (+/- SD) levels of serum Lp[a] were not elevated in the hemodialysis patients compared to controls (19.3 +/- 18.0 mg/dl vs. 18.3 +/- 10.4 mg/dl, respectively). We found no statistically significant correlation of Lp[a] with either cholesterol, triglycerides, HDL-C or apoproteins. However, compared with controls, more than fivefold as many of those hemodialysis patients had high risk (greater than 30 mg/dl) concentrations of Lp[a]. Lp[a] tended to increase in hemodialysis patients with diabetes mellitus and/or ischemic heart disease. In patients with high levels of Lp[a] (greater than 30 mg/dl), Lp[a] tended to correlate positively with cholesterol, LDL-, HDL-C, apo B or apo B/AI. Incidence of IHD was also elevated in these patients. Along with other known risk factors such as hyperlipidemia and hypertension, an increased concentration of Lp[a] may play an important role in accelerating development of atherosclerosis in this condition.  相似文献   
995.
Oral adsorbent (AST-120) reduces blood levels of urea and creatinine in experimental studies. It has also been shown to retard the progression of chronic renal failure in clinical studies. In the present study, the effect of AST-120 was examined in the rat model of subtotal nephrectomy (sNPX). This experimental model of chronic renal failure is characterized by glomerular hyperfunction, glomerular hypertrophy, increased mesangial trapment of macromolecules and subsequent glomerular sclerosis. We report the effect of AST-120 on glomerular hyperfunction, glomerular hypertrophy and mesangial trapment of macromolecules in the early stage and glomerular function and histology in the late stage of the rat model of sNPX. From 2 days after sNPX, rats were fed regular rat chow with (AST group: AST) or without (control) AST-120. At 2 weeks, iron dextran (ID) was injected intravenously. Three days after the injection, mesangial trapment of ID was largely ameliorated in AST when compared with control (p less than 0.02). The value of mean planar area of glomerulus (PAmean) in AST was significantly lower than that in control (p less than 0.05). At 2 and 9 weeks, the values of GFR and RPF in AST were all statistically higher than those in control. At 9 weeks, whereas average glomerular sclerosis index (SI: 0-4 scale) was 1.07 in control, significantly lower SI (0.57) was noted in AST (p less than 0.05). Thus, AST-120 has effects on glomerular hypertrophy, increased mesangial trapment of macromoleculus and finally the progression of chronic renal failure in the rat model of sNPX. The effects are not through reducing glomerular hyperfunction.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
996.
M Yano  T Otsuka 《Brain and nerve》1988,40(10):925-928
In 9 severe head injuries whose respiration was controlled by a ventilator, continuous measurements of energy expenditure (MEE) were carried out by the ERICA Metabolic Computer. Age was ranged 19 to 69 years old (Mean 48.3 years). Glasgow Coma Scale score was 3 to 11 which were assessed the best score during 6 hours of admission. The MEE was carried out within 7 days of admission and was continued to measure more than 3 days. It measured O2 consumption and CO2 output, and calculated the indirect energy expenditure. The data were displayed and recorded every 1, 15, 60 min. The value of MEE was compared with predicted energy expenditure (PEE) which was calculated by the Harris-Benedict formula. Out of 9 patients, 6 patients were survived. High dose barbiturate therapy was performed in 7 patients to control and decrease the intracranial hypertension. Of them 3 patients died. The value of MEE in all 9 patients was variable from 77% to 212% of PEE. The value of MEE in 6 survived patients was 98.0 to 212.0% of PEE. Out of 6 patients, 4 patients who were administered high dose barbiturate showed variable data of MEE. Two patients showed about 100% of the PEE, one showed about 150%, and another one about 200%. Remaining 2 survivors who were not administered barbiturate showed about 125% of PEE, which was low value. These results were divided into two groups. In 2 patients, the value of MEE was 150% or more in spite of barbiturate therapy. In remaining 7 patients, the value of MEE was 125% or less of PEE.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
997.
The purpose of this study was to evaluate the use of serum fibronectin and serum somatomedin-C as nutritional markers during enteral nutrition support (ENS) of critically ill, traumatized patients using an enteral product containing high concentrations of branched-chain amino acids. Twelve critically injured patients received a standard enteral formula with 30 g of a 44% branched-chain amino acid supplement added to each liter of formula. Fibronectin concentration, somatomedin-C concentration, and nitrogen balance were measured on study days 1, 4, 7, 14, 21, 28 or until adequate oral intake began. Both fibronectin and somatomedin-C concentrations increased significantly from baseline by day 7 of ENS. Nitrogen balance increased significantly from baseline by day 4. On days 14 and 21, only somatomedin-C and nitrogen balance increased significantly from baseline. Nitrogen balance was significantly correlated with somatomedin-C concentration (r = 0.53, p less than 0.01), cumulative caloric intake (r = 0.68, p less than 0.01), and cumulative nitrogen intake (r = 0.72, p less than 0.01). The results of this study suggest that serum somatomedin-C is useful and serum fibronectin has potential in monitoring nutrition support response in critically ill, traumatized patients.  相似文献   
998.
Amino acid concentrations were measured in the cord blood serum from neonates following 23-41 weeks gestation. These values were then correlated with the gestational age of the newborns. A significant (p less than 0.05) correlation was observed with the concentrations of six amino acids, and five of these correlations were negative. The significance of these normative data are discussed and compared with currently available cord blood aminogram data.  相似文献   
999.
Elevation of prostaglandins and protein in the aqueous humor is an immediate response to Yag-laser anterior capsulotomy. There was a significant correlation between prostaglandins and thromboxane to the elevation of intraocular pressure. The elevation of protein concentration was proportional to the elevation of prostaglandin F1, but not to thromboxane. The biochemical changes in the aqueous humor were more severe as laser power was increased above 3 mj. While the role of prostaglandins in the elevation of intraocular pressure is uncertain, the present data recommend the selection of laser power below 3 mj to avoid pressure rise instead of inhibition of all prostaglandin synthesis by medication.  相似文献   
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