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   5651篇
  免费   250篇
  国内免费   38篇
耳鼻咽喉   73篇
儿科学   75篇
妇产科学   94篇
基础医学   604篇
口腔科学   269篇
临床医学   384篇
内科学   1395篇
皮肤病学   46篇
神经病学   337篇
特种医学   296篇
外科学   1039篇
综合类   24篇
预防医学   205篇
眼科学   48篇
药学   448篇
中国医学   29篇
肿瘤学   573篇
  2021年   74篇
  2020年   46篇
  2019年   75篇
  2018年   70篇
  2017年   70篇
  2016年   70篇
  2015年   75篇
  2014年   109篇
  2013年   130篇
  2012年   219篇
  2011年   253篇
  2010年   139篇
  2009年   134篇
  2008年   240篇
  2007年   233篇
  2006年   243篇
  2005年   264篇
  2004年   229篇
  2003年   260篇
  2002年   266篇
  2001年   189篇
  2000年   184篇
  1999年   189篇
  1998年   73篇
  1997年   72篇
  1996年   42篇
  1995年   51篇
  1994年   60篇
  1993年   45篇
  1992年   131篇
  1991年   119篇
  1990年   117篇
  1989年   122篇
  1988年   133篇
  1987年   144篇
  1986年   139篇
  1985年   120篇
  1984年   90篇
  1983年   61篇
  1981年   36篇
  1979年   51篇
  1978年   32篇
  1977年   41篇
  1975年   37篇
  1971年   48篇
  1970年   42篇
  1969年   44篇
  1968年   30篇
  1967年   32篇
  1966年   35篇
排序方式: 共有5939条查询结果,搜索用时 734 毫秒
1.
2.
3.
PURPOSE: To clarify the appropriate concentration and dose of hypertonic saline solution (HSS) for preventing delayed neuronal death in the hippocampal CA1 subfield after transient forebrain ischemia in gerbils. METHODS: Thirty gerbils were randomly assigned to five groups: physiological saline solution (PSS) group, ischemia/reperfusion treated with PSS 2 mL x kg(-1); 5% HSS group, treated with 5% HSS 2 mL x kg(-1); 7.5% HSS group, treated with 7.5% HSS 2 mL x kg(-1); 10% HSS group, treated with 10% HSS 2 mL x kg(-1); 20% HSS group, treated with 20% HSS 2 mL x kg(-1). Transient forebrain ischemia was induced by occluding the bilateral common carotid arteries for four minutes. Five days later, histopathological changes in the hippocampal area were examined, and the degenerative ratio of the pyramidal cells were measured according to the following formula: (number of degenerative pyramidal cells/total number of pyramidal cells per 1 mm of hippocampal CA1 subfield) x 100. RESULTS: In PSS and 20% groups, neuronal cell damage was observed five days after ischemia. In the other three groups, these changes were not observed. The degenerative ratios of pyramidal cells were as follows; PSS group: 91.6 +/- 5.6%, 5% HSS group: 7.2 +/- 1.6%, 7.5% group: 8.3 +/- 1.4%, 10% HSS group: 6.2 +/- 1.1%, 20% HSS group: 85.8 +/- 8.7% (P < 0.05; PSS and 20% HSS vs three other groups). CONCLUSION: This study demonstrates that 5, 7.5 or 10% HSS 2 mL x kg(-1) may prevent delayed neuronal death in the hippocampal CA1 subfield after cerebral ischemia/reperfusion in gerbils.  相似文献   
4.
5.
Kindling of the visual cortex in cats: comparison with amygdaloid kindling   总被引:3,自引:0,他引:3  
Kindling of the primary visual cortex (VC) was compared with that of the amygdala in cats. VC kindling was basically similar to kindling of the amygdala in that daily electrical stimulation can lead to the development of a generalized convulsion in most subjects, a growth of afterdischarges in their configuration and duration, and a reduction of the afterdischarge threshold. The kindling response of the VC differed from that of the amygdala in a number of respects, i.e., a high afterdischarge threshold, a different pattern of behavioral seizure development, an abrupt growth of electroclinical seizures coincident with the onset of a generalized convulsion, an intersubject variability in seizure susceptibility, and a marked seizure instability. In VC kindling the afterdischarge propagation into the amygdala was not observed until the generalized convulsion developed, and the early involvement of afterdischarge was seen in the pulvinar, lateral geniculate body, and superior colliculus. These data suggest that a neural mechanism different from amygdaloid kindling may participate in VC kindling, and that the subcortical structures of the visual system are involved in the preferential pathway for a seizure generalization from the VC.  相似文献   
6.
7.
Two tumor-associated cellular proteins, 82k/6.3 (MW/pI) and 61k/7.5, which were detected by two-dimensional gel electrophoresis, were studied by biochemical and immunological methods. In two-dimensional gel electrophoresis, 82k/6.3 and 61k/7.5 were rich in colon cancer tissue compared with normal colon mucosa, and they were also detected in fetal intestines. This shows that both proteins might be involved in category of oncofetal proteins. The localization of 82k/6.3 and 61k/7.5 was investigated by subcellular fractionation. They were rich in microsomal fraction, but not found in both nuclear and mitochondrial fractions. In binding reaction with seven kinds of lectins, 82k/6.3 reacted with RCAI, DBA and WGA, where 61k/7.5 reacted with RCAI, DBA, WGA, UEAI and SBA. Transferrin reacted with only RCAI. Each hybrid producing monoclonal antibody against 82k/6.3 or 61k/7.5 was generated by fusing spleen cells of BALB/c mice immunized by the two proteins and mouse myeloma cells. Each monoclonal antibody was specified in enzyme-linked immunoassay. In indirect immuno-fluorescent studies, monoclonal antibodies against 82k/6.3 and 61k/7.5 reacted with cytoplasma and membrane of human cancer cells. This result strongly suggests the localization of the two proteins demonstrated by subcellular fractionation.  相似文献   
8.
9.
We previously selected a group of hypertension candidate genes by a key word search using the OMIM database of NCBI and validated 525 coding single nucleotide polymorphisms (SNPs) in 179 hypertension candidate genes by DNA sequencing in a Japanese population. In the present study, we examined the association between 61 non-synonymous SNPs and blood pressure variations and hypertension. We used DNA samples taken from 1,880 subjects in the Suita study, a population-based study using randomly selected subjects. Analyses of covariance adjusting for age, body mass index, hyperlipidemia, diabetes, smoking, drinking, and antihypertensive medication revealed that 17 polymorphisms in 16 genes (APOB, CAST, CLCNKB, CTNS, GHR, GYS1, HF1, IKBKAP, KCNJ11, LIPC, LPL, P2RY2, PON2, SLC4A1, TRH, VWF) were significantly associated with blood pressure variations. Multivariate logistic regression analysis with adjustment for the same factors revealed that 11 polymorphisms in 11 genes (CAST, CTLA4, F5, GC, GHR, LIPC, PLA2G7, SLC4A1, SLCI8A1, TRH, VWF) showed significant associations with hypertension. Five polymorphisms in five genes, CAST(calpastatin), LIPC (hepatic lipase), SLC4A1 (band 3 anion transporter), TRH (thyrotropin-releasing hormone), and VWF (von Willebrand factor), were significantly associated with both blood pressure variation and hypertension. Thus, our study suggests that these five genes were susceptibility genes for essential hypertension in this Japanese population.  相似文献   
10.
BACKGROUND: Based on epidemiological studies of prevalence, sensitization as well as pollen survey, it is presumed that airborne Japanese cedar pollen (JCP) and cypress (JCyP) have increased progressively for past 40 years. However, because of their large yearly variations, accurate objective and scientific study is required to confirm if it is true or not. METHODS: We analyzed the time trends of JCP and JCy separately in 11 districts throughout Japan where have records of continuous past survey from 1986 to 2005, by regression analysis using net pollen count and their 3 and 5 running means. RESULTS: When significant slope of regression line (regression coefficient) is assumed as p < 0.05 and R2 (coefficient of determination) >0.4, significant increase in airborne pollen was revealed in the use of 5 point running mean (6 districts of total 11 in JCP and 5 in JCyP) but not net count or 3 point running mean because of correction of statistic error due to large yearly variations. This study suggested that our method used for analysis of a recent increase in airborne JCP and JCyP was useful and scientific.  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