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   1130篇
  免费   49篇
  国内免费   13篇
耳鼻咽喉   1篇
儿科学   54篇
妇产科学   45篇
基础医学   123篇
口腔科学   16篇
临床医学   132篇
内科学   141篇
皮肤病学   5篇
神经病学   317篇
特种医学   118篇
外科学   53篇
综合类   13篇
预防医学   72篇
眼科学   4篇
药学   75篇
肿瘤学   23篇
  2021年   20篇
  2020年   6篇
  2019年   11篇
  2018年   13篇
  2017年   14篇
  2016年   12篇
  2015年   16篇
  2014年   20篇
  2013年   50篇
  2012年   58篇
  2011年   71篇
  2010年   48篇
  2009年   60篇
  2008年   43篇
  2007年   43篇
  2006年   31篇
  2005年   30篇
  2004年   26篇
  2003年   38篇
  2002年   29篇
  2001年   33篇
  2000年   31篇
  1999年   34篇
  1998年   29篇
  1997年   21篇
  1996年   21篇
  1995年   23篇
  1994年   30篇
  1993年   18篇
  1992年   31篇
  1991年   20篇
  1990年   31篇
  1989年   30篇
  1988年   27篇
  1987年   16篇
  1986年   20篇
  1985年   18篇
  1984年   7篇
  1983年   17篇
  1982年   8篇
  1981年   9篇
  1980年   5篇
  1979年   13篇
  1978年   8篇
  1977年   5篇
  1976年   5篇
  1968年   7篇
  1966年   5篇
  1965年   3篇
  1912年   3篇
排序方式: 共有1192条查询结果,搜索用时 31 毫秒
1.
Seventeen autistic children were matched for age, race, and sex with 17 nonautistic children, and group differences in social skills were assessed. Appropriate social skills and levels of inappropriate assertiveness/impulsiveness were assessed and evaluated using the Matson Evaluation of Social Skills with Youngsters (MESSY). Significant differences in both the appropriate and inappropriate social behaviors displayed by the two groups were found. The implications of these results are discussed.  相似文献   
2.
3.
A retrospective study of 42 adolescent patients diagnosed as being pregnant between June 1987 and February 1990 at the Downtown Health Center (DHC), an inner city pediatric primary care clinic, was conducted to determine whether patients referred to a hospital-based Teen Pregnancy Clinic (TPC) were seen within a reasonable period of time. The frequency of sexually transmitted diseases (STDs) was also determined when these women were initially seen at TPC. Only 5 of the 42 patients seen at DHC had a pelvic exam prior to referral. Of the 40 patients seen at TPC, 20% were not seen until four weeks or more after initial diagnosis. Fifty percent had a STD. Pediatricians should recognize that pregnant teenagers may have a significant delay between diagnosis of pregnancy and entry into obstetrical care. Pelvic exam including cultures for STDs is recommended prior to referral.  相似文献   
4.
目的 探索LDH实验检测细胞活力的可行性。方法 原代培养骨髓细胞和软骨细胞,用LDH实验测定上述两组细胞的活力,并与镜下活体观察到细胞的生长状况相比较。与目前比较成熟的测定细胞活力的MTS实验的测得的值相比较。结果 LDH实验对上述两组细胞的活力的测定结果与镜下活体观察到的结果相符合。与MTS实验的测得的结果经统计学处理无显著差异。结论 LDH实验可用于细胞活力的直接测定,而对活细胞的生存、繁殖无影响。  相似文献   
5.
BACKGROUND: Interdialytic weight gain (IDWG) can be reduced by lowering the dialysate sodium concentration ([Na]) in haemodialysis patients. It has been assumed that this is because thirst is reduced, although this has been difficult to prove. We compared thirst patterns in stable haemodialysis patients with high and low IDWG using a novel technique and compared the effect of low sodium dialysis (LSD) with normal sodium dialysis (NSD). METHODS: Eight patients with initial high IDWG and seven with low IDWG completed hourly visual analogue ratings of thirst using a modified palmtop computer during the dialysis day and the interdialytic day. The dialysate [Na] was progressively reduced by up to 5 mmol/l over five treatments. Dialysis continued at the lowest attained [Na] for 2 weeks and the measurements were repeated. The dialysate [Na] then returned to baseline and the process was repeated. RESULTS: Baseline interdialytic day mean thirst was higher than the dialysis day mean for the high IDWG group (49.9+/-14.0 vs 36.2+/-16.6) and higher than the low weight gain group (49.9+/-14.0 vs 34.1+/-14.6). This trend persisted on LSD, but there was a pronounced increase in post-dialysis thirst scores for both groups (high IDWG: 46+/-13 vs 30+/-21; low IDWG: 48+/-24 vs 33+/-18). The high IDWG group demonstrated lower IDWG during LSD than NSD (2.23+/-0.98 vs 2.86+/-0.38 kg; P<0.05). CONCLUSIONS: Our results indicate that patients with high IDWG experience more intense feelings of thirst on the interdialytic day. LSD reduces their IDWG, but paradoxically increases thirst in the immediate post-dialysis period.  相似文献   
6.
A study was performed to determine quantitatively the alterations in phosphorus metabolite concentrations and pH in regions of the human brain damaged by chronic stroke. Image-guided phosphorus-31 magnetic resonance spectroscopy was performed on the brains of eight healthy subjects and six patients with cerebral infarction of more than 3 months duration. Phosphorus metabolite concentrations in infarcted regions were reduced 8%-67%. Significant decreases occurred in phosphomonoester (PME), phosphodiester (PDE), and adenosine triphosphate (ATP) concentrations, while inorganic phosphate (Pi) and phosphocreatine (PCr) concentrations showed smaller, nonsignificant decreases. The PCr/ATP ratio was significantly increased, while the ATP/Pi ratio was somewhat lower. The phospholipid ratio PDE/PME was also significantly increased, while the ratios of phospholipid (PME, PDE) to phosphate (PCR, Pi) metabolites were significantly decreased. The pH of the infarcted region indicated significantly more alkalinity than in the normal brain. The results suggest that chronic stroke is associated with significant changes in brain metabolite concentrations and pH that are different from those reported for other brain diseases.  相似文献   
7.
Morphological comparison of sperm in raw ejaculates and swim-ups showed that the swim-up process does not simply increase the proportion of 'normal' sperm. Rather, sperm of specific morphologies have characteristic grades of upward motility.  相似文献   
8.
Parathyroid hormone secretion is negatively regulated by a 7- transmembrane domain, G-protein coupled Ca(2+)-sensing receptor. We hypothesized that activating mutations in this receptor might cause autosomal dominant hypoparathyroidism (ADHP). Consistent with this hypothesis, we identified, in two families with ADHP, heterozygous missense mutations in the Ca(2+)-sensing receptor gene that cosegregated with the disorder. None of 50 normal controls had either mutation. We also identified a de novo, missense Ca(2+)-sensing receptor mutation in a child with severe sporadic hypoparathyroidism. The amino acid substitution in one ADHP family affected the N-terminal, extracellular domain of the receptor. The other mutations involved the transmembrane region. Unlike patients with acquired hypoparathyroidism, patients with these mutations had hypercalciuria even at low serum calcium concentrations. Their greater hypercalciuria presumably reflected activation of Ca(2+)-sensing receptors in kidney cells, where the receptor negatively regulates calcium reabsorption. This augmented hypercalciuria increases the risk of renal complications and thus has implications for the choice of therapy.   相似文献   
9.
10.
Knowledge of the immune response to rotavirus is crucial for vaccine development. We compared an epitope-blocking assay (EBA) that uses VP7-specific monoclonal antibodies with neutralization assays (NAs) with polyclonal antisera for detecting serum antibody responses after natural rotavirus infection in children. Twenty-six serum pairs from children living in an orphanage with and without symptoms during two rotavirus outbreaks were evaluated for VP7 type 1-, 2-, 3-, and 4-specific antibody responses. In the first outbreak, which was caused by a VP7 type 3 strain, homotypic antibody responses were detected in 11 of 11 symptomatic children by NA and in 10 of 11 symptomatic children by EBA. Heterotypic antibody responses were detected more frequently (12 of 15 children) by NA than by EBA, and the heterotypic epitope-blocking antibody responses occurred in children older than 14 months of age. Antibody responses in asymptomatic children were more commonly detected by EBA than by NA. EBA results from the sera of children in the second outbreak indicated that it was caused by VP7 type 4, whereas NA results suggested it was caused by VP7 type 3. Our results confirm that EBA is a sensitive and specific method for determining VP7 type-specific immune responses after natural rotavirus infections.  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