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   2236篇
  免费   133篇
  国内免费   5篇
耳鼻咽喉   9篇
儿科学   164篇
妇产科学   36篇
基础医学   292篇
口腔科学   36篇
临床医学   141篇
内科学   384篇
皮肤病学   310篇
神经病学   27篇
特种医学   86篇
外科学   265篇
综合类   304篇
一般理论   1篇
预防医学   122篇
眼科学   16篇
药学   74篇
  1篇
中国医学   3篇
肿瘤学   103篇
  2022年   26篇
  2021年   41篇
  2020年   20篇
  2019年   30篇
  2018年   34篇
  2017年   20篇
  2016年   33篇
  2015年   58篇
  2014年   71篇
  2013年   61篇
  2012年   82篇
  2011年   74篇
  2010年   89篇
  2009年   79篇
  2008年   98篇
  2007年   101篇
  2006年   96篇
  2005年   93篇
  2004年   98篇
  2003年   67篇
  2002年   84篇
  2001年   66篇
  2000年   58篇
  1999年   62篇
  1998年   44篇
  1997年   43篇
  1996年   39篇
  1995年   34篇
  1994年   38篇
  1993年   19篇
  1992年   37篇
  1991年   48篇
  1990年   51篇
  1989年   50篇
  1988年   48篇
  1987年   46篇
  1986年   38篇
  1985年   43篇
  1984年   31篇
  1983年   15篇
  1982年   16篇
  1981年   15篇
  1979年   18篇
  1978年   17篇
  1977年   12篇
  1976年   15篇
  1975年   10篇
  1974年   13篇
  1973年   17篇
  1972年   10篇
排序方式: 共有2374条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
BACKGROUND: The present study was aimed to define the gender ratio, familial occurrence, age of onset, precipitating factors, clinical types, nail and joint involvement of psoriasis in childhood and adolescence in Turkey. METHODS: A total of 61 children with psoriasis under 18 years old were evaluated retrospectively, for age, gender, age of disease onset, family history, concomitant disease, the clinical type of psoriasis, clinical localization, nail and joint involvement and treatment modalities. RESULTS: Of the patients, 23 (37.70%) were boys and 38 (62.30%) were girls. Mean age was 9.28 +/- 4.02 years in girls and 11.18 +/- 3.85 years in boys (9.96 +/- 4.03 years in all children). Mean age at the onset of the disease was 6.81 +/- 4.11 years in girls and 7.03 +/- 4.28 years in boys (6.89 +/- 4.14 years in all patients). In 14 (23%) cases, a positive family history was detected. The most frequent probable triggering factors were upper respiratory tract infections (14.8%) and positive throat culture for A group ss-hemolytic streptococcus (21.3%). Frequency of emotional stress and psychiatric morbidity were 54% and 9.8%, respectively. The most frequent localizations at onset were trunk (44.3%), extremities (54.0%), and scalp (36.0%). Three children (4.9%) had a history of dissemination from psoriatic diaper rash. In total, 51 (83.6%) patients presented with psoriasis vulgaris, eight (13.1%) with generalized pustular psoriasis, and the remaining two (3.3%) with erythrodermic psoriasis. CONCLUSION: The incidence of psoriasis among dermatological patients in childhood and adolescence was 3.8%. The disease tends to appear earlier in girls than boys. The authors suggested that stress and upper respiratory infections are the most important triggering factors in childhood and adolescence psoriasis.  相似文献   
5.
6.
Sixty drinking water samples collected from various sources in different areas of Delhi during epidemic of cholera and gastroenteritis were analysed for bacteriological standards. Only 27 (45 per cent) samples were found to be satisfactory for human consumption. Remaining thirty-three (55 per cent) samples showed presence of coliform organisms with MPN value ranging from 10 to 1800+ per 100 ml. Among these positive samples, 31 (93.9 per cent) samples contained faecal coli. Twenty out of thirty (66.6 per cent) Hand pump, 9 out of 21 (42.8 per cent) Taps 2 out of 4 (50 per cent) Tube well and 2 out of 5 (40 per cent) of miscellaneous sources showed contamination with coliform organisms.  相似文献   
7.
8.
9.
10.
Attempts to develop a hemoglobin-based red cell substitute have spanned many decades, but no clinically useful product has been produced to date. The issues preventing clinical application primarily are ones of safety--not efficacy. Numerous animal studies have documented the efficacy of SFH. Although effective, the solution has limitations that have caused concern. Oncotic considerations limit the concentration of the infusate SFH to 6 to 8 g/dL, or half-normal. Owing to the loss of organic phosphate modulators of P50, such as 2,3-DPG, the P50 of SFH is typically between 12 and 14 mm Hg, which is also half the normal value. And finally, the intravascular half-life of SFH is too short, ranging only from 2 to 6 hr. Polymerization provides a means of correcting these limitations. The high oxygen affinity can be greatly diminished by covalent binding of pyridoxal-5'-phosphate to the N-terminal of the chains. Colloid osmotic pressure exerted by a protein solution is proportional to the number of discrete colloid particles. Through polymerization, the number of colloid particles is reduced, leading to a decrease in COP. Data show that this can be achieved in a reproducible fashion. The rate at which COP diminishes determines the yield of polymeric species, as well as their molecular weight distribution. Polymerization can be controlled to result in a yield of 75% to 85% polymers with a molecular weight distribution of 128 to 400 kd. The number average and the weight average molecular weights indicate that the large proportion of polymers represent the cross linking of two tetramers. The data that reflect the interaction of oxygen with poly-SFH-P indicate that the oxygen carrying function of hemoglobin has not been significantly altered by the chemical modifications. The binding coefficient of oxygen is unchanged. As anticipated, there is a loss of cooperativity (diminished Hill coefficient) between the hemoglobin chains, suggesting structural restrictions in the polymeric species because of cross linking. A reduced alkaline Bohr effect is the expected result, and data confirm this. Finally, some increase in oxygen affinity is to be expected with polymerization. This is indeed the case, although the P50 of poly-SFH-P is comparable to banked blood (18 to 22 mm Hg). To be clinically useful, a modified hemoglobin solution requires a reasonable shelf-life.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
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