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   46760篇
  免费   3868篇
  国内免费   92篇
耳鼻咽喉   499篇
儿科学   1905篇
妇产科学   1555篇
基础医学   6029篇
口腔科学   569篇
临床医学   5426篇
内科学   8830篇
皮肤病学   894篇
神经病学   5248篇
特种医学   1164篇
外国民族医学   2篇
外科学   5131篇
综合类   459篇
现状与发展   1篇
一般理论   77篇
预防医学   5894篇
眼科学   859篇
药学   2841篇
中国医学   39篇
肿瘤学   3298篇
  2023年   639篇
  2022年   1032篇
  2021年   2019篇
  2020年   1223篇
  2019年   1766篇
  2018年   1990篇
  2017年   1361篇
  2016年   1546篇
  2015年   1607篇
  2014年   2117篇
  2013年   2684篇
  2012年   3883篇
  2011年   3792篇
  2010年   1924篇
  2009年   1647篇
  2008年   2570篇
  2007年   2698篇
  2006年   2356篇
  2005年   2164篇
  2004年   1878篇
  2003年   1622篇
  2002年   1450篇
  2001年   408篇
  2000年   421篇
  1999年   451篇
  1998年   326篇
  1997年   215篇
  1996年   188篇
  1995年   187篇
  1994年   175篇
  1993年   164篇
  1992年   266篇
  1991年   270篇
  1990年   265篇
  1989年   228篇
  1988年   206篇
  1987年   200篇
  1986年   223篇
  1985年   228篇
  1984年   165篇
  1983年   154篇
  1982年   116篇
  1981年   109篇
  1979年   170篇
  1978年   120篇
  1977年   118篇
  1975年   109篇
  1974年   137篇
  1973年   114篇
  1972年   109篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
111.
The research evaluated an intervention strategy designed to prevent skin cancer in young adolescents. The intervention used parents as change agents to effectively communicate the risks of skin cancer and encourage their children to avoid high-risk sun-related behaviors while increasing positive sun-safe behaviors. Three hundred and forty parents in two regions of the United States were educated about the dangers of risky sun behaviors and how to convey information about skin cancer prevention to their children. Parents were then encouraged to talk with their children about these issues over a 1-month period prior to the onset of summer. Following this time period, children whose parents received and implemented the intervention materials were compared with a control sample of 129 children. These two groups were matched on age, gender, and school on number of sunburns and sunburn severity, attitudes and beliefs, and sunbathing behavior. Children in the treatment condition differed significantly from controls in the predicted directions on all outcome variables. The findings are discussed in terms of reducing skin cancer risk behaviors of children via parent-based intervention approaches.  相似文献   
112.
Cann AJ  Fandrich SE  Heaphy S 《Virus genes》2005,30(2):151-156
Virus DNA was isolated from horse faeces and cloned in a sequence-independent fashion. 268 clones were sequenced and 178140 nucleotides of sequence obtained. Statistical analysis suggests the library contains 17560 distinct clones derived from up to 233 different virus genomes. TBLASTX analysis showed that 32% of the clones had significant identity to GenBank entries. Of these 63% were viral; 20% bacterial; 7% archaeal; 6% eukarya; and 5% were related to mobile genetic elements. Fifty-two percent of the virus identities were with Siphoviridae; 26% unclassified phages; 17% Myoviridae; 4% Podoviridae; and one clone (2%) was a vertebrate Orthopoxvirus. Genes coding for predicted virus structural proteins, proteases, glycosidases and nucleic acid-binding proteins were common.  相似文献   
113.
114.
We employ diffuse optical tomography (DOT) to track treatment progress in a female subject presenting with locally advanced invasive carcinoma of the breast during neoadjuvant chemotherapy. Three-dimensional images of total hemoglobin concentration and scattering identified the tumor. Our measurements reveal tumor shrinkage during the course of chemotherapy, in reasonable agreement with magnetic resonance images of the same subject. A decrease in total hemoglobin concentration contrast between tumor and normal tissue was also observed over time. The results demonstrate the potential of DOT for measuring physiological parameters of breast lesions during chemotherapy.  相似文献   
115.
Rearrangements or deletions of chromosome 17 are the most frequentlyobserved genetic changes identified in breast tumors. Molecularanalyses suggest that in addition to the p53 gene on 17p13.1there may be at least three other tumor suppressor genes onchromosome 17 involved in breast cancer. Regions of loss ofheterozygosity (LOH) identified on 17p13.3 and 17q12-qter occurfrequently in breast tumors, and the BRCA-1 gene has been mappedto 17q21 by genetic linkage analysis. Here we provide biologicalevidence for the presence of a growth suppressor gene(s) onchromosome 17 that results In the In vitro growth suppressionof the p53 wild-type MCF 7 breast cancer cell line. We haveIntroduced a normal chromosome 17 into MCF 7 cells by microcellmediatedchromosome transfer (MMCT), and demonstrate that cells growtharrest before 10 to 12 population doublings. In contrast, theintroduction of a normal chromosome 13 had no effect upon growthof these cells either In vitro or In vivo. These data providedirect functional evidence for the presence of a growth suppressorgene(s) on chromosome 17, which is not p53, and which may representone of several gene(s) that play a critical role in the developmentof breast cancer.  相似文献   
116.
Eighty-one to 100% of nymphs and females of the human body louse (Pediculus humanus humanus) that fed artificially on blood containing 2.5-10 ng ivermectin/ml died. The mortality of nymphs and female lice fed on rabbits treated with 200 micrograms/kg ivermectin was very high during the first two to three days, then declined sharply, reaching the level of the controls on day six. Nymphs were more sensitive than females. The average number of eggs laid by surviving females and the percentage that hatched from those eggs were lower than in controls.  相似文献   
117.
Pathologic rupture of the spleen is a rare phenomenon in acute lymphocytic leukemia, and its mechanism is unknown. This complication has been seen almost exclusively in men, and at ages much older than those of the majority of patients who have this leukemia; these unusual features are also unexplained. A case of acute lymphoctyic leukemia with pathologic rupture of the spleen in which the pathologic findings suggest that the splenic rupture was due to infiltration and destruction of the splenic capsule by leukemic cells is reported.  相似文献   
118.
119.
Cardiac responses to non-signal stimuli and to signal stimuli in a vigilance task were examined in children born with congenital heart defects (CHD), and in normal and attention deficit disordered (ADD) subjects. Overall task performance was lower in subjects with heart defects and in the ADD group. Cardiac measures revealed that normal children displayed significantly larger heart rate deceleration to the target stimuli than did either of the clinical groups. Moreover, although no group differences were observed in the cardiac response to non-signal auditory stimuli, exaggerated heart rate deceleration was observed to vibrotactile stimuli in both the clinical groups. Regression analyses revealed that the magnitude of the cardiac response to somatosensory stimuli was predictive of task performance (both within and between subject groups), with larger responses associated with higher error rates and lower perceptual sensitivity. Results were suggestive of a predictive relationship between somatosensory reactivity and neuropsychological maturation.  相似文献   
120.
A patient with the clinical stigmata of gonadal dysgenesis is presented. Cytogenetic investigations revealed two distinct structural chromosome rearrangements. One of these, an isochromosome for the long arm of the X, proved to be a dicentric element following C-banding. The second abnormality, an inherited familial marker, was a pericentric inversion of No. 2 [(inv 2) (p15q21)].  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