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   1450篇
  免费   108篇
  国内免费   4篇
耳鼻咽喉   1篇
儿科学   107篇
妇产科学   36篇
基础医学   174篇
口腔科学   10篇
临床医学   136篇
内科学   186篇
皮肤病学   4篇
神经病学   120篇
特种医学   31篇
外科学   197篇
综合类   83篇
一般理论   1篇
预防医学   188篇
眼科学   15篇
药学   170篇
肿瘤学   103篇
  2021年   14篇
  2020年   10篇
  2019年   28篇
  2018年   32篇
  2017年   20篇
  2016年   21篇
  2015年   17篇
  2014年   31篇
  2013年   51篇
  2012年   69篇
  2011年   68篇
  2010年   50篇
  2009年   41篇
  2008年   62篇
  2007年   73篇
  2006年   45篇
  2005年   49篇
  2004年   68篇
  2003年   66篇
  2002年   50篇
  2001年   57篇
  2000年   45篇
  1999年   48篇
  1998年   22篇
  1997年   21篇
  1996年   15篇
  1995年   10篇
  1994年   14篇
  1993年   12篇
  1992年   29篇
  1991年   29篇
  1990年   33篇
  1989年   22篇
  1988年   38篇
  1987年   22篇
  1986年   22篇
  1985年   28篇
  1984年   11篇
  1983年   14篇
  1981年   11篇
  1980年   8篇
  1979年   14篇
  1977年   11篇
  1975年   14篇
  1974年   8篇
  1973年   13篇
  1972年   8篇
  1970年   10篇
  1969年   13篇
  1964年   8篇
排序方式: 共有1562条查询结果,搜索用时 15 毫秒
1.
2.
The effects of acetazolamide on the developing rodent limb bud were postulated to result from a reduction of intracellular pH (pHi). Embryonic intracellular pH was calculated from transplacental distribution of the weak acid, 5,5'-dimethyloxazolidine-2,4-dione, in teratogenically sensitive (C57BL/6) and resistant (SWV) inbred mice. pHi was reduced by acetazolamide treatment in C57 embryos and limb buds but not in SWV samples. Acetazolamide teratogenesis can be exacerbated by coadministration of amiloride, presumably through inhibition of Na+/H+ exchange attributable to the latter agent. pHi reduction after such treatment was more profound than after acetazolamide alone, providing further support for the central hypothesis. pH was also reduced in other embryonic (embryo plasma) and extraembryonic compartments (exocoelomic fluid, amniotic fluid). pH changes in these compartments could also lead or contribute to abnormal development.  相似文献   
3.
A review of 174 consecutive patients admitted with a diagnosis of perforated peptic ulcer to eight Hunter Region hospitals during 1979–86 is presented. Among the female admissions, the proportion of patients > 70 years of age was twice that in males. One-third of all perforations were in females who accounted for two-thirds of all perforated gastric ulcers. Multivariate analysis revealed that perforations located in the stomach and older age were both significant independent variables adversely affecting outcome following surgery. In contrast, shock at presentation and delay in operating were not statistically significant independent risk factors.  相似文献   
4.
5.
6.
BACKGROUND: Antisocial personality disorder (ASPD) in DSM-IV is unique among personality disorder diagnoses in requiring the individual to satisfy a number of childhood criteria in addition to relevant traits exhibited in adulthood. We examined the validity of this childhood requirement. METHODS: Personality disordered individuals assessed using the International Personality Disorder Examination and exhibiting a sufficient number of adult antisocial traits to meet criterion A of DSM-IV were subdivided into those who exhibited antisocial traits in both adulthood and childhood and those who had such traits in adulthood only. The two groups were then compared on a number of historical, clinical, and self-report measures. RESULTS: Thirty individuals meeting both childhood and adult criteria (ASPD) were compared with 39 meeting adult antisocial criteria only (ASS). Few differences were found between the two groups on the measures examined, although those in the ASPD group appeared more severe and had higher anger scores on the STAXI-2 psychometric test. CONCLUSIONS: This failure to find clinically important differences between the two groups is in agreement with previous reports and needs to be taken into account in future revisions of ASPD in DSM.  相似文献   
7.
Fathers of children born to young urban mothers   总被引:1,自引:0,他引:1  
Fathers of babies born to a sample of urban mothers younger than 18 at delivery ranged in age from 14-50 and were, on average, 2-4 years older than the mothers. Among the adolescent women who had given birth to their first child, 28 percent of the partners of black women and 45 percent of the partners of white women were 20 years of age or older. The educational attainment of the fathers was very low, particularly among older whites. At approximately 15 months after the child's birth, 36 percent of the fathers were neither in school nor working. Three-quarters of the pregnancies among the young white mothers and 95 percent of those among the black mothers were unplanned, but only six percent of the white mothers and 16 percent of the black mothers were using a contraceptive at the time of conception. Only 16 percent of the fathers were living with or married to the mother of their child at 15 months after birth. About 90 percent of the fathers had spent time with their child during that period, but frequency of contact declined markedly with time. Overall, 20 percent of the fathers had children by other women.  相似文献   
8.
In acute quadriplegia we have noted that about one in five patients develops unexplained production of markedly excessive and tenacious bronchial mucus. Spontaneous recovery from mucus hypersecretion usually occurs within weeks to months. Mucus samples collected from 12 patients have been found to be abnormal. Macromolecular contents of single aspirates yielded as much as 500 mg. Analytical ultracentrifuge analysis showed the mucus to contain considerable epithelial glycoprotein (GP) of typical buoyant density; its amino acid and carbohydrate compositions were characteristic of the GP from hypersecretory bronchial mucus such as in chronic bronchitis and cystic fibrosis. In five patients studied after recovery from hypersecretion, there tended to be relatively less GP. The mucus samples contained a high density glycoconjugate (GC): this had sugars of GP but also reacted positively with a monoclonal antibody to keratan sulfate. Its amino acid composition was different from that of GP: threonine was lower and glycine was higher than in GP. In mucus from one patient who died, chondroitin sulfate ABC and hyaluronic acid were identified as well. This suggests proteoglycans are involved in the pathophysiology of mucus hypersecretion. The sudden onset and spontaneous recovery of hypersecretion suggests that it is not due to gland hypertrophy. We speculate that in acute quadriplegia it is due to disturbed neuronal control of bronchial mucus gland secretion, perhaps related to initial disappearance and later reappearance of peripheral sympathetic nervous system tone.  相似文献   
9.
Somatostatin: evidence for a role in thermal nociception   总被引:5,自引:0,他引:5  
In barbiturate-anaesthetized spinalized cats, antibody microprobes were used to investigate the release of immunoreactive somatostatin (irSS) in the lumbar dorsal horn in response to cutaneous stimuli. In the absence of applied stimulation, a significant basal release of irSS was present in the region of the substantia gelatinosa. Such release was not increased by innocuous or noxious cutaneous mechanical stimuli nor by innocuous thermal stimuli, but was increased by noxious thermal stimulation. The magnitude of this noxious heat-evoked release was estimated by comparing in vivo microprobes with those used to detect known concentrations of somatostatin in vitro. Pairs of microprobes were used to detect simultaneous release of both irSS and immunoreactive substance P in the substantia gelatinosa. The results support the putative role of somatostatin in the spinal transmission of thermal nociceptive information.  相似文献   
10.
A possible etiologic role for Epstein-Barr virus (EBV) in Hodgkin's disease (HD) was investigated by probing for EBV genome in 52 biopsy specimens involved with HD and 43 hyperplastic lymph node specimens. Using dot-blot hybridization (Bam HIW probe), Southern blot hybridization (Xho I probe), and polymerase chain reaction analyses, 27%, 27%, and 58% of the nodes with HD were positive for EBV genome, respectively, as compared to 16%, 14%, and 43% in the hyperplastic lymph nodes. Clonal and nonclonal episomal EBV and linear replicating EBV genome were present in both conditions. Immunoglobulin heavy chain gene rearrangements were found in two clonal and two nonclonal EBV-positive HD cases, but not in the lymphoid hyperplasia cases. These findings and other recent reports showing EBV genome in benign lymphoid cells by in situ hybridization in Hodgkin's disease suggest that the characteristics of EBV infection in HD could be explained by the reactive cellular milieu, especially in the setting of defective immunity. The identification of EBV genome in Reed-Sternberg cells may, therefore, be a nonspecific phenomenon.  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