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   705738篇
  免费   48869篇
  国内免费   1304篇
耳鼻咽喉   9166篇
儿科学   23267篇
妇产科学   17603篇
基础医学   110382篇
口腔科学   19955篇
临床医学   63748篇
内科学   134284篇
皮肤病学   16159篇
神经病学   49428篇
特种医学   25737篇
外国民族医学   76篇
外科学   104459篇
综合类   14818篇
现状与发展   2篇
一般理论   160篇
预防医学   51384篇
眼科学   16318篇
药学   53941篇
  3篇
中国医学   2359篇
肿瘤学   42662篇
  2019年   5430篇
  2018年   7857篇
  2017年   6104篇
  2016年   6818篇
  2015年   7548篇
  2014年   10260篇
  2013年   15376篇
  2012年   20487篇
  2011年   21480篇
  2010年   12715篇
  2009年   11928篇
  2008年   19983篇
  2007年   21501篇
  2006年   21894篇
  2005年   20432篇
  2004年   19982篇
  2003年   18937篇
  2002年   18448篇
  2001年   36325篇
  2000年   36894篇
  1999年   30377篇
  1998年   7875篇
  1997年   6662篇
  1996年   6969篇
  1995年   6627篇
  1994年   6096篇
  1993年   5589篇
  1992年   22967篇
  1991年   22924篇
  1990年   22309篇
  1989年   22076篇
  1988年   20035篇
  1987年   19417篇
  1986年   18467篇
  1985年   17305篇
  1984年   12697篇
  1983年   10741篇
  1982年   5921篇
  1979年   11518篇
  1978年   8128篇
  1977年   6832篇
  1976年   6594篇
  1975年   7268篇
  1974年   8498篇
  1973年   8141篇
  1972年   7658篇
  1971年   7127篇
  1970年   6877篇
  1969年   6306篇
  1968年   5780篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Cyclosporine A inhibition of microcystin toxins   总被引:2,自引:0,他引:2  
Cyclosporine A (CyA) given i.v. at a dose of 1.25 mg/mouse blocks a subsequent i.v. lethal dose (1.7-1.8 x LD50) of microcystin-LR for 24 hr, and is about 50% protective at 48 hr. Conversely, the fraction of mice that can be rescued by CyA (0.2 mg/mouse) after a lethal dose of microcystin-LR decreases rapidly with a pharmacodynamic half-time of only about 100 sec. The prophylactic action of CyA was tested against lethal doses of four microcystins. The acute lethality of 1.7-1.8 x LD50 dose of microcystin-LR, -RR, -LY, or -LA given 1 hr after administration of 0.2 mg of CyA is 0%, 0%, 58%, or 100%, respectively. Even a 0.6 mg/mouse dose of CyA is ineffective prophylaxis against a lethal dose of microcystin-LA. The inhibitory potency of CyA on microcystin toxicity can be completely reversed by the single L-amino acid substitution of alanine for arginine in the microcystin.  相似文献   
992.
Orthotopic liver transplantation was performed in 20 pigs. Serum total bile acids (STBA) were determined and their profile compared with standard early function parameters: total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactic acid. In phase I, the STBA level was 32.89 +/- 1.29 mumol/l. In phase II, STBA accumulated to 84.46 +/- 15.25 mumol/l (p less than 0.01), followed by hepatic clearance in phase III (63.61 +/- 9.71 mumol/1; NS). Between phase III and 6- and 12-hour samples, STBA decreased progressively, reaching values of 33.63 +/- 7.05 mumol/l at 24 h. AST was elevated in phases I, II, III, and at 6, 12 and 24 h (p less than 0.001), as was ALT (but with insignificant differences). Thus, STBA and their profile appear to be earlier and more specific indicators of early graft function than conventional parameters.  相似文献   
993.
Pharmacokinetic , bacteriological and clinical studies on norfloxacin (NFLX), a quinolone-carboxylic acid antibacterial agent, were conducted in the pediatric field. 1. Serum concentrations and urinary excretion of NFLX after single dose of 2.2 approximately 5.6 mg/kg (mean 4.4 +/- 1.2 mg/kg) were determined in 13 children with ages between 6 and 11 years. The mean peak serum concentration of the drug was 0.37 +/- 0.20 micrograms/ml at 2 hours after administration. The mean half-life of the drug in serum was 2.8 +/- 0.4 hours and the serum concentration at 8 hours was 0.11 +/- 0.06 micrograms/ml. The mean urinary concentration reached a maximum of 125.2 +2- 166.2 micrograms/ml in pooled urine from 0 to 2 hours and the mean urinary recovery rate in the first 8 hours after administration was 22.1 +/- 6.0%. A dose-response relationship was observed between doses/body weight and peak serum concentrations. 2. The clinical efficacy, bacteriological efficacy and the safety of NFLX were evaluated in 65 pediatric patients with ages between 2 years 10 months and 15 years 7 months with infections. In 62 assessable cases (acute purulent tonsillitis 9 cases, acute pneumonia 3 cases, chronic rhinitis 1 case, urinary tract infections 15 cases, and acute colitis 34 cases), clinical efficacies were excellent in 48 cases, good in 13 cases, and fair in 1 case with an overall efficacy rate of 98.4%. Staphylococcus aureus 1 strain, Staphylococcus epidermidis 1 strain, Escherichia coli 10 strains, Salmonella sp. 5 strains, Morganella morganii 1 strain, Pseudomonas aeruginosa 3 strains, Haemophilus parainfluenzae 1 strain and Campylobacter jejuni 12 strains were isolated from the patients as pathogens. Bacteriologically, all of these strains were eradicated except that 3 strains of C. jejuni only decreased. With regard to side effects, dizziness and nausea were observed in 1 case each but they were slight and the continuation of the treatment was possible. No abnormal laboratory test data were observed. From the above results, NFLX was considered to be a useful drug for the treatment of pediatric infections.  相似文献   
994.
995.
Renal and urological anomalies in Down syndrome (DS) have received little attention compared with the nephrourological findings described in other chromosomal abnormalities. Renal hypoplasia, hydroureteronephrosis, ureterovesical and ureteropelvic junction obstruction, and vesicoureteral reflux, but not posterior urethral valves, have been associated with DS. We report the occurrence of posterior urethral valves in three male infants with DS at a single institution. All had multiple urological procedures for correction or palliation of obstruction. Children with DS may have an increased risk for developing posterior urethral valves and obstructive uropathy. Furthermore, they may also develop chronic renal failure secondary to posterior urethral valves. Therefore, we suggests that infants with DS be screened with ultrasonography for renal and urological abnormalities early in life and, if abnormal, a contrast voiding cystourethrogram be performed to rule out posterior urethral valves or other bladder or urethral abnormalities. A review of the renal and urological anomalies in DS reported in the literature since 1960 is presented.  相似文献   
996.
Phagocytic leukocytes were separated from the peripheral blood of chickens using a one-step Percoll density gradient technique. Heterophils recovered from two fractions of the gradient were of 96.9 to 99.8% purity and were fully viable and functional, as demonstrated by their capacity to phagocytose latex beads and staphylococci. Adherent mononuclear cells were cultured from specific gradient fractions and shown to phagocytose staphylococci.  相似文献   
997.
998.
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