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   654018篇
  免费   32869篇
  国内免费   783篇
耳鼻咽喉   8588篇
儿科学   20998篇
妇产科学   15216篇
基础医学   109288篇
口腔科学   16631篇
临床医学   56279篇
内科学   125517篇
皮肤病学   15676篇
神经病学   43878篇
特种医学   22584篇
外国民族医学   54篇
外科学   93443篇
综合类   8247篇
现状与发展   2篇
一般理论   145篇
预防医学   50770篇
眼科学   14862篇
药学   49887篇
  1篇
中国医学   1673篇
肿瘤学   33931篇
  2021年   6542篇
  2019年   6699篇
  2018年   10490篇
  2017年   6950篇
  2016年   7527篇
  2015年   8336篇
  2014年   10548篇
  2013年   15617篇
  2012年   24376篇
  2011年   26815篇
  2010年   14705篇
  2009年   12150篇
  2008年   23118篇
  2007年   25303篇
  2006年   24220篇
  2005年   23583篇
  2004年   22341篇
  2003年   21379篇
  2002年   20543篇
  2001年   25976篇
  2000年   26972篇
  1999年   21959篇
  1998年   5778篇
  1997年   4709篇
  1996年   4761篇
  1995年   4397篇
  1992年   15659篇
  1991年   16865篇
  1990年   16864篇
  1989年   16393篇
  1988年   14964篇
  1987年   14815篇
  1986年   13827篇
  1985年   13222篇
  1984年   9838篇
  1983年   8328篇
  1982年   4346篇
  1979年   9320篇
  1978年   6618篇
  1977年   5370篇
  1976年   5747篇
  1975年   6905篇
  1974年   7782篇
  1973年   7519篇
  1972年   6911篇
  1971年   6627篇
  1970年   6201篇
  1969年   5795篇
  1968年   5479篇
  1967年   4902篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
.We report five patients with Laurence-Moon-Bardet-Biedl syndrome (LMBBS) who had renal involvement. Intravenous pyelography showed bilateral or unilateral calyceal clubbing and blunting in all patients. In addition, one patient had a parapelvic cyst in the left kidney and another had bilateral lobulated renal outlines of the fetal type. One patient had a urinary concentrating defect and two patients showed increased fractional sodium excretion. Estimated tubular phosphate reabsorption values were in normal limits in all of five patients. No patient had a urine acidification defect, proteinuria, glycosuria, or hyperaminoaciduria. One patient died from end-stage renal failure. The remaining four patients had normal serum creatinine values and estimated creatinine clearances. 99mTechnetium-diethylenetriamine pentaacetate renal scanning showed prolonged and delayed concentration and delayed excretion in three of the four patients who survived. A focal scar was determined on the left kidney of one of four patients by 99mtechnetium-dimercaptosuccinic acid renal scanning. All LMBBS cases with or without renal symptoms should be routinely evaluated for renal abnormalities. Renal scanning is a valuable method, especially for determining the renal involvement in the early stage of disease. Received November 14, 1995; received in revised form and accepted May 23, 1996  相似文献   
962.
963.
964.
965.
Nutritional dwarfing refers to a condition in which maladaptive eating patterns play a primary role in poor linear growth and delayed pubertal development. The present controlled study assesses whether nutritionally dwarfed children and adolescents differ in their psychosocial adjustment from healthy children and adolescents of comparable height in ways that might account for their undernutrition. Children with nutritional dwarfing (n = 16) were compared by standardized questionnaires with a short-stature (ie, heights below the fifth percentile) control group composed of children and adolescents with constitutional growth delay and/or familial short stature (n = 31). Scores on a self-report screening questionnaire for eating disorders did not differentiate the groups. Moreover, the vast majority of nutritionally dwarfed patients expressed a desire to have a heavier physical appearance. Whereas the groups were generally similar in self-perceptions of domain-specific competencies and positive psychosocial adjustment, the parents of nutritionally dwarfed children reported that their children showed significantly fewer externalized behavior problems. These findings suggest the existence of an eating disturbance that compromises growth in childhood and/or adolescence which, unlike anorexia nervosa, is not associated with evidence of psychopathology.  相似文献   
966.
Elevated serum sodium and potassium levels were recently observed when sampled through a heparin-bonded umbilical catheter and measured with certain ion-selective electrodes. The cationic surfactant, benzalkonium chloride (BZC), is known to falsely elevate those cations in serum. Inasmuch as most heparin-bonded umbilical catheters use BZC during the bonding process, an in vitro study was performed to estimate the quantity of BZC released and the duration of sodium and potassium elevations during pooled sera infusion. Three heparin-bonded umbilical catheters and 3 silastic umbilical catheters were first flushed with 0.3 mL of normal saline and then perfused with pooled sera (sodium, 142 mEq/L; potassium, 4.6 mEq/L) at 2.5 microL/h. Effluent samples were collected from 0 to 8 hours and analyzed by ion-selective electrodes. Elevated serum sodium concentrations from 160 to greater than or equal to 250 mEq/L and potassium concentrations from 6.0 to greater than or equal to 9.6 mEq/L were observed. The BZC concentration in the catheter effluent was measured by mass spectrometry, with peak values of 10 micrograms/mL detected by this method. When varying concentrations of BZC (1 to 100 micrograms/mL) were added directly to pooled serum, a dose-dependent increase in serum sodium was observed. These data demonstrate that BZC released from heparin-bonded umbilical catheters elevates serum electrolyte values measured with some ion-selective electrodes. The observed increase in sodium and potassium concentrations may lead to clinical errors in management. Benzalkonium chloride is associated with myriad of linical symptomatology. Whether this amount of BZC is toxic in the small premature neonate is presently unknown.  相似文献   
967.
Overall 1580 children from the regions with unsafe radiation situation were examined comprehensively at different times after the accident. The data obtained were correlated to the results of examining 610 children of the control group. The basic group children manifested a higher incidence of diverse alterations on the part of many organs and systems, which was accompanied by an increase of free radical processes signs of destabilization of cellular membranes, activation of blood cell metabolism, suppression of the T cell component of immunity in the presence of vegetovascular dysfunction. A tendency was noted toward normalization of these alterations seen over time after the accident. No clear-cut dose-effect dependence was found.  相似文献   
968.
969.
The problems of surgical treatment of the low fistulous forms of anal atresia in children with the use of postero-sagittal approach are considered. A modification of this method is described. The postoperative results are presented, and the possible complications as well. A conclusion about the advantages of the operative approach described is made.  相似文献   
970.
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