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   834篇
  免费   30篇
  国内免费   28篇
儿科学   63篇
妇产科学   10篇
基础医学   71篇
口腔科学   14篇
临床医学   53篇
内科学   109篇
皮肤病学   17篇
神经病学   21篇
特种医学   158篇
外科学   50篇
综合类   135篇
预防医学   53篇
眼科学   49篇
药学   57篇
  1篇
肿瘤学   31篇
  2023年   5篇
  2022年   3篇
  2021年   9篇
  2020年   4篇
  2018年   8篇
  2017年   8篇
  2016年   7篇
  2015年   10篇
  2014年   16篇
  2013年   28篇
  2012年   28篇
  2011年   25篇
  2010年   34篇
  2009年   39篇
  2008年   35篇
  2007年   39篇
  2006年   35篇
  2005年   19篇
  2004年   23篇
  2003年   18篇
  2002年   19篇
  2001年   24篇
  2000年   19篇
  1999年   19篇
  1998年   44篇
  1997年   37篇
  1996年   41篇
  1995年   28篇
  1994年   24篇
  1993年   21篇
  1992年   9篇
  1991年   7篇
  1990年   7篇
  1989年   23篇
  1988年   19篇
  1987年   16篇
  1986年   24篇
  1985年   22篇
  1984年   9篇
  1983年   5篇
  1982年   18篇
  1981年   9篇
  1980年   12篇
  1979年   2篇
  1978年   6篇
  1977年   9篇
  1976年   9篇
  1975年   7篇
  1955年   2篇
  1953年   2篇
排序方式: 共有892条查询结果,搜索用时 31 毫秒
31.
背景和目的:最近的研究结果表明,对其他一线药物和注射类药物(如卡那霉素、卷曲霉素)等耐药是影响耐多药结核病(MDR-TB)患者治疗效果的独立危险因素.本研究旨在明确耐其他一线药物和注射类药物对韩国不合并人免疫缺陷病毒(HIV)感染的MDR-TB患者临床疗效的影响.方法:采用回顾性队列研究分析1996年1月至2005年12月首尔国家大学附属医院治疗的211例MDR-TB患者治疗效果,排除7例丢失和7例迁出,对197例患者进行了最终分析.  相似文献   
32.
在2型糖尿病患者中,反映炎症和内皮功能障碍的生物标志已经与心血管疾病和代谢调节联系起来。二甲双胍和促胰岛素分泌剂被证明有相同的抗高血糖作用。此研究比较了二甲双胍和促胰岛素分泌剂瑞格列奈在非肥胖的2型糖尿病患者的心血管疾病生物标志上的效能。  相似文献   
33.
A baby with unilateral cleft lip, midline cleft palate and hypertelorism developed meningitis in the first 48 h of life. Examination of the nasopharynx showed a soft tissue mass, which was confirmed as a basal encephalocele by computed tomography. There was also congenital hydrocephalus and the corpus callosum was absent. Surgical treatment included repair of the anterior basal skull defect, repair of the lip and palate, and ventriculo-peritoneal shunt. There is currently evidence of developmental delay and right-sided visual impairment due to Morning Glory syndrome. This case demonstrates that basal encephalocele should be considered in any baby with midline facial deformity who develops meningitis.  相似文献   
34.
Ethics in public health policy is given the least importance and rarely discussed. Resolving ethical issues in public health is often an arduous task as these are complicated and require careful handling. Using four case studies, we discuss issues pertaining to pertussis and brain damage, water fluoridation and dental caries, infection with the human immunodeficiency virus and the right to marriage, and the debate surrounding universal salt iodization. The core issue in all these examples pertains to the relevance of ethics in public health policy.  相似文献   
35.
Carcinogenic tobacco-specific nitrosamines are present in tobacco products and are believed to play a significant role in human cancers associated with tobacco use. Additional amounts of tobacco-specific nitrosamines could be formed endogenously. We tested this hypothesis by treating rats with nicotine and sodium nitrite and analyzing their urine. Initially, we treated groups of rats with (S)-nicotine (60 micromol/kg) and NaNO2 (180 micromol/kg), (S)-nicotine alone, NaNO2 alone or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, 12 nmol/kg) by gavage twice daily for 4 days. We collected urine and analyzed for two metabolites of NNK; 4-(methylnitrosamino)-1-(3- pyridyl)-1-butanol and its glucuronide. We did not detect these metabolites in the urine of rats treated with nicotine alone or nicotine plus NaNO2, indicating that endogenous conversion of nicotine to NNK did not occur. However, the urine did contain N'- nitrosonornicotine (NNN), N'-nitrosoanabasine (NAB) and N'- nitrosoanatabine (NAT). Analysis of the (S)-nicotine used in this experiment demonstrated that it contained trace amounts of nornicotine, anabasine and anatabine. In a second experiment, we used an identical protocol to compare the endogenous nitrosation of this (S)-nicotine with that of synthetic (R,S)-nicotine, which did not contain detectable amounts of nornicotine, anabasine or anatabine. NNN (0.53 x 10(-3)% of nicotine dose), NAB (0.68%) and NAT (2.1%) were detected in the urine of the rats treated with the (S)-nicotine and NaNO2. NNN (0.47 x 10(- 3)% of dose), but not NAB or NAT, was present in the urine of the rats treated with synthetic (R,S)-nicotine and NaNO2. NNN probably formed via nitrosation of metabolically formed nornicotine. These results demonstrate for the first time that endogenous formation of tobacco- specific nitrosamines occurs in rats treated with tobacco alkaloids and NaNO2. The potential significance of the results with respect to nitrosamine formation in people who use tobacco products or nicotine replacement therapy is discussed.   相似文献   
36.
The present study investigated the expression and distribution of three isoforms of nitric oxide synthase (NOS) in different anatomical regions of the human stomach and in gastric neoplastic tissues by immunohistochemistry using specific antibodies. Intracellular localization of individual isoenzymes of NOS was detected in normal gastric mucosa. Gastric cancer tissues had a marked reduction of all three NOS isoforms expression. The expression of the endothelial NOS, neuronal NOS and inducible NOS in the tumor tissue was significantly lower than in normal gastric mucosa (P = 0.01, P = 0.02, P < 0.01, respectively). In the tumor tissue the expression of inducible NOS was significantly lower than the expression of both constitutive forms of NOS (P < 0.01). There was a tendency to higher expression of both constitutive forms of NOS in earlier stages T2 of the tumor compared to advanced T4 tumor. In contrast, the expression of inducible NOS was higher than in the advanced T4 tumor than in the earlier stages T2 of the tumor. The mapping of the expression of endothelial NOS, neuronal NOS and inducible NOS in human stomach showed higher expression of NOS isoforms in the distal third than in the proximal third of the stomach (P = 0.03, P = 0.04, P = 0.01, respectively). We conclude that there is greater expression of NOS in the stomach corpus and in antrum than in the proximal third of the normal human stomach mirroring the anatomical predilection of common pathological changes in this part of the human stomach. Furthermore, there was loss of the expression of individual isoenzymes in gastric neoplasms.   相似文献   
37.
Hecht  SS; Spratt  TE; Trushin  N 《Carcinogenesis》1997,18(9):1851-1854
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) is an important metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1- (3-pyridyl)-1-butanone (NNK). Using the chiral derivatizing agent, (R)- (+)-alpha-methylbenzyl isocyanate [(R)-(+)-MBIC], previous work has shown that the enantiomeric ratio of metabolically formed NNAL and its glucuronide derivative may be species dependent. However, the absolute configuration of such NNAL has not been previously reported. Synthetically prepared racemic NNAL was converted to diastereomeric esters by reaction with (R)-(+)- and (S)-(-)-alpha-methoxy-alpha- (trifluoromethyl)phenylacetic acid (MTPA) chloride (Mosher's reagent) and the products were characterized by 1H-NMR. Based on chemical shift data, the absolute configuration of NNAL in each diastereomeric ester was assigned. Hydrolysis of (R)-NNAL-(R)-MTPA gave (R)-NNAL. This was converted to the corresponding carbamate by reaction with (R)-(+)-alpha- MBIC and the absolute configurations of the diastereomeric carbamates formed by reaction of (R)- and (S)-NNAL with (R)-(+)-MBIC were thereby assigned. Conversion of metabolically produced NNAL to the same carbamates allowed us to assign the NNAL formed from NNK by rat liver microsomes as (R)-NNAL. The major and minor NNAL-glucuronide diastereomers found in the urine of patas monkeys and humans exposed to NNK were similarly assigned; they were formed from (R)-NNAL and (S)- NNAL, respectively.   相似文献   
38.
39.
High prevalence of endemic goitre (54%) and endemic cretinism (3.5%) exist in Sikkim. The level of intellectual functioning and motor performance were assessed in 90 school children in the age group of 10 to 12 years selected randomly from four severely iodine-deficient villages. Bender Visual Motor Gestalt Test, Binet-Kamat Test for mental ability and Raven’s Coloured Progressive Matrices were the tests used. The results show an impairment in intellectual and other neuropsychological functions in a high percentage of the children. Visuomotor coordination was poor in 62 (69%). Binet-Kamat test results showed that 19 (21%) children were intellectually subnormal (IQ<70). Majority of the children (>80%) had significant impairment in language, meaningful memory, non-meaningful memory, conceptual thinking, numerical reasoning and motor skills. The children did better on non-verbal reasoning and social intelligence. Goitre was detected in 82 (91.1%). Urine samples for iodine estimations was collected from every second child examined. The mean urinary iodine concentration was 4.23 ug/dl (SD 2.16). Urinary iodine concentration was less than 2 micro gm/dl in 26.1% (11 children) and less than 5 micro gm/dl in 84.8% (39 children) indicating severe iodine deficiency. The test results show impairment of psychomotor development in children born and brought up in iodine-deficient environment.  相似文献   
40.
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