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   842篇
  免费   53篇
  国内免费   35篇
耳鼻咽喉   5篇
儿科学   69篇
妇产科学   4篇
基础医学   131篇
口腔科学   28篇
临床医学   104篇
内科学   155篇
皮肤病学   34篇
神经病学   15篇
特种医学   184篇
外科学   37篇
综合类   24篇
预防医学   60篇
眼科学   14篇
药学   34篇
中国医学   1篇
肿瘤学   31篇
  2022年   3篇
  2021年   8篇
  2020年   3篇
  2019年   8篇
  2018年   16篇
  2017年   12篇
  2016年   10篇
  2015年   18篇
  2014年   12篇
  2013年   27篇
  2012年   16篇
  2011年   10篇
  2010年   44篇
  2009年   37篇
  2008年   12篇
  2007年   24篇
  2006年   18篇
  2005年   36篇
  2004年   18篇
  2003年   6篇
  2002年   9篇
  2001年   15篇
  2000年   9篇
  1999年   22篇
  1998年   50篇
  1997年   47篇
  1996年   49篇
  1995年   35篇
  1994年   41篇
  1993年   35篇
  1992年   19篇
  1991年   17篇
  1990年   12篇
  1989年   26篇
  1988年   47篇
  1987年   24篇
  1986年   19篇
  1985年   33篇
  1984年   8篇
  1983年   6篇
  1982年   7篇
  1981年   8篇
  1980年   8篇
  1979年   7篇
  1978年   5篇
  1977年   6篇
  1976年   12篇
  1975年   3篇
  1970年   3篇
  1967年   2篇
排序方式: 共有930条查询结果,搜索用时 0 毫秒
91.
92.
Breast milk samples from three groups of Brazilian women were evaluated: G1, mothers delivering term babies of low birth weight (n=16); G2, mothers delivering preterm babies of appropriate birth weight (n = 20); G3, mothers delivering term babies of appropriate birth weight ( n = 30). Milk samples were obtained at 48 h and on the 7th, 15th, 30th and 60th days after delivery and they were analyzed for lysozyme and total IgA levels and for the presence of specific antibodies against Poliovirus types I, II, III, Rotavirus, Herpes simplex virus, Varicella zoster and Cytomegalovirus. The groups were not statistically different in relation to mother's age, parity, type of delivery or socio-economic levels. IgA levels were higher in both low-birth-weight groups (G1 & G2) compared to the control group (G3) throughout the study period. Lysozyme levels decreased up to the 15th day, increasing thereafter up to the 60th day in all groups. Specific antibodies were detected throughout the study period, with no differences among groups. We conclude that breast milk composition of mothers delivering low-birth-weight babies (G1 & G2) was similar despite the different gestational ages.  相似文献   
93.
Immune deficiencies in chronic intestinal pseudo-obstruction   总被引:1,自引:0,他引:1  
Aim: Chronic intestinal pseudo-obstruction has been associated with urinary disorders, myopathy, and ophthalmoplegia in adults and cholelithiasis in children. We observed a high percentage of total-parenteral-nutrition-dependent patients with pseudo-obstruction and recurrent infections requiring gammaglobulin infusions. Methods: AH records for 23 children with chronic intestinal pseudo-obstruction (10 females and 13 males, mean age 9.8 y ± 4.9 y, range 4–24 y) referred for a nutritional evaluation from 1992 to 1995 were reviewed. Chronic intestinal pseudo-obstruction was diagnosed by clinical, radiographic findings and antroduodenal manometry. Intestinal full-thickness biopsies were performed in seven children. Results: Hypogammaglobulinemia was diagnosed in 18 patients (78%): 16 patients had various immunoglobulin deficiencies and 2 had selective antibody deficiency. Intravenous gammaglobulin was administered in 14 patients. Other medical conditions affecting the children are summarized as follows: autonomic dysfunction in 10 patients (43%), recurrent hypoglycemia in 9 (39%), asthma in 9 (39%), cholecystitis in 7 (30%), low serum carnitine level in 6 (26%), urinary dysfunction in 6 (26%), pancreatitis in 5 (22%), behavioral problems in 5 (22%), myopathy in 2 (9%), idiopathic thrombocytopenia in 2 (8%), velopharyngeal insufficiency in 1 (4%), oculocutaneous albinism in 1 (4%), Pierre-Robin syndrome in 1 (4%), and protein C deficiency in 1 (4%). Munchausen syndrome was suspected in two patients. Conclusions: Chronic intestinal pseudo-obstruction appears to be associated with immune deficiencies. It is unclear if the immune deficiencies, intestinal pseudo-obstruction, and the other medical conditions have a common underlying etiology. Repeated infections may be due to impaired immune function in children with chronic intestinal pseudo-obstruction. We recommend screening for immune deficiencies in children with chronic intestinal pseudo-obstruction.  相似文献   
94.
95.
96.
Interleukin-12 p70 (IL-12p70) heterodimer, composed of p35 and p40 subunits, is a major Th1-driving cytokine, promoting cell-mediated immunity. In contrast, IL-12p40 homodimer, secreted by APC in the absence of p35 expression, and free p40 monomer do not mediate IL-12 activity but act as IL-12 antagonists. Here it is reported that prostaglandin E(2) (PGE(2)), an inflammatory mediator with a previously known Th2-driving function, dose-dependently enhances the IL-12p40 mRNA expression and the secretion of IL-12p40 protein in human tumor necrosis factor-alpha (TNFalpha)-stimulated immature dendritic cells (DCs). This effect is selective and is not accompanied by the induction of IL-12p35 expression or by secretion of IL-12p70 heterodimer. Inability of TNFalpha/PGE(2) to induce IL-12p70 was not compensated by interferon gamma (IFNgamma), which strongly enhanced the lipopolysaccharide (LPS)-induced IL-12p70 production. In addition to the selective induction of IL-12p40 in TNFalpha-stimulated DCs, PGE(2) inhibited the production of IL-12p70 and IL-12p40 in DCs stimulated with LPS or CD40 ligand. These data suggest an additional level of the Th2-promoting activity of PGE(2), via selective induction of IL-12p40. Selective induction of IL-12p40 and suppression of bioactive IL-12p70 may have negative impact on anticancer vaccination with PGE(2)-matured DCs. (Blood. 2001;97:3466-3469)  相似文献   
97.
保证输血时血清学方面的安全,首要的是对受血者与献血者ABO血型定型,血清学检查通常分两个步骤.正定型通常使用鼠源单克隆抗体检测红细胞表面是否存在A或B抗原.互补的实验即反定型,利用当红细胞上缺乏A或B抗原时,人群可天然产生相对应的抗体的原理,检测血清中是否存在抗-A或者抗-B抗体.确定了受血者红细胞表面的ABO抗原以及血浆中的抗体,便能确定血型,为其提供相合的血液.  相似文献   
98.
Hepatitis C virus among blood donors: follow-up study   总被引:1,自引:0,他引:1  
BACKGROUND: The exact significance of antibodies to hepatitis C virus (HCV) in blood donors remains unknown. Confirmatory tests of anti-HCV- reactive serum and HCV RNA by polymerase chain reaction (PCR) are used to refute a large proportion of false-positive results. STUDY DESIGN AND METHODS: Ninety-two blood donors who were anti-HCV reactive in a first-generation enzyme-linked immunosorbent assay (ELISA) were reevaluated 10 months later with a second-generation ELISA (ELISA-2) as well as with second-generation recombinant immunoblot assay (RIBA-2) and by PCR. RESULTS: Twenty-five (43.9%) of the 57 ELISA-2-positive donors were confirmed as positive by RIBA-2; of these, 84 percent were HCV RNA positive in PCR. Of the 57 who were still anti-HCV positive, 46 were followed up and tested again in the same manner 2 years after the first screening. At that time, the pattern was little changed: 94 percent of RIBA-2- and PCR-positive donors remained positive. Of RIBA-2- and PCR-positive blood donors, 62 percent had abnormal alanine aminotransferase levels in at least one of the three evaluations. Among the anti-HCV-positive donors confirmed by RIBA-2, 60 percent, versus 12.6 percent in the control group, had a significantly (p < 0.001) more frequent risk factor for HCV infection, due to parenteral exposure to blood. CONCLUSION: These data confirm a good correlation between RIBA-2 reactivity and the detection of HCV RNA in a population of anti-HCV- positive blood donors.  相似文献   
99.
The development of efficacious prophylactic human papillomavirus vaccines provided an opportunity for the primary prevention of related infections and diseases. Certain oncogenic human papillomaviruses that preferentially infect the genital epithelium cause cervical cancer and a substantial proportion of anal, penile, vaginal, vulvar and oropharyngeal cancers. Following extensive clinical trials demonstrating their efficacy and safety, two vaccines have been in global use for over 6 years. This review summarises the accumulated evidence regarding their high level of efficacy, safety in population usage, reductions in genital warts, infections and cervical disease following their adoption, and facilitators and barriers to achieving high vaccination coverage. The review also discusses practical issues and frequently asked questions regarding duration of effect, vaccination of women treated for cervical disease and alternate vaccination schedules, as well as the need to review cervical screening strategies in the post‐ vaccination environment.  相似文献   
100.
保证输血时血清学方面的安全,首要的是对受血者与献血者ABO血型定型,血清学检查通常分两个步骤.正定型通常使用鼠源单克隆抗体检测红细胞表面是否存在A或B抗原.互补的实验即反定型,利用当红细胞上缺乏A或B抗原时,人群可天然产生相对应的抗体的原理,检测血清中是否存在抗-A或者抗-B抗体.确定了受血者红细胞表面的ABO抗原以及血浆中的抗体,便能确定血型,为其提供相合的血液.  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