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   11843篇
  免费   1238篇
  国内免费   85篇
耳鼻咽喉   72篇
儿科学   479篇
妇产科学   378篇
基础医学   1687篇
口腔科学   236篇
临床医学   1341篇
内科学   2477篇
皮肤病学   170篇
神经病学   842篇
特种医学   712篇
外科学   1509篇
综合类   343篇
一般理论   7篇
预防医学   1162篇
眼科学   120篇
药学   936篇
  2篇
中国医学   3篇
肿瘤学   690篇
  2021年   149篇
  2020年   108篇
  2019年   161篇
  2018年   176篇
  2017年   153篇
  2016年   140篇
  2015年   199篇
  2014年   289篇
  2013年   390篇
  2012年   503篇
  2011年   543篇
  2010年   350篇
  2009年   322篇
  2008年   466篇
  2007年   510篇
  2006年   475篇
  2005年   458篇
  2004年   417篇
  2003年   386篇
  2002年   397篇
  2001年   354篇
  2000年   362篇
  1999年   326篇
  1998年   249篇
  1997年   265篇
  1996年   258篇
  1995年   214篇
  1994年   212篇
  1993年   203篇
  1992年   254篇
  1991年   283篇
  1990年   254篇
  1989年   243篇
  1988年   259篇
  1987年   270篇
  1986年   249篇
  1985年   248篇
  1984年   180篇
  1983年   153篇
  1982年   116篇
  1981年   110篇
  1980年   89篇
  1979年   108篇
  1978年   93篇
  1977年   95篇
  1976年   95篇
  1975年   92篇
  1973年   89篇
  1972年   85篇
  1971年   77篇
排序方式: 共有10000条查询结果,搜索用时 890 毫秒
121.
Defects in the lipoprotein lipase (LPL) gene are associated with dyslipidemia in the general population. Several rare mutations in the gene, as well as two common coding region polymorphisms, D9N and N291S, exhibit deleterious effects on circulating lipid levels. Using a linkage-based approach, we have identified a large Utah kindred segregating the D9N variant in the LPL gene. The kindred was ascertained for premature coronary heart disease and was expanded based on familial dyslipidemia. A genomic scan identified a region of linkage including LPL, and mutation screening identified the segregating variant. In the kindred, the variant shows high penetrance for a hypoalphalipoproteinemia phenotype, but is also associated with hypertriglyceridemia and elevated insulin levels. The strength of linkage was dependent on the combination of phenotype definition and model parameters, favoring the use of a MOD score approach. Most other studies of LPL have proceeded by mutation screening of randomly chosen individuals or selected affected probands; this is the first example identifying a segregating LPL mutation using direct linkage.  相似文献   
122.
We examined 81 cases of Hodgkin's disease for evidence of the t(14;18) translocation, using the polymerase chain reaction assay on lysates of formalin-fixed, paraffin-embedded tissue. Seven of 74 amplifiable cases (9%) were positive for the translocation, which involves the bcl-2 oncogene and the immunoglobulin heavy chain gene. Two of these cases were sequenced and the breakpoints had the same pattern found in follicular lymphoma. The nuclei from one of the cases were sorted into large and small subpopulations. The t(14;18) signal was more intense in the large nucleus subpopulation, which contained a greater proportion of Reed-Sternberg-like nuclei. These results are consistent with the hypothesis that Reed-Sternberg cells carry the translocation, but they do not exclude the possibility that the translocation is found in cells representing the reactive component of Hodgkin's disease. The results also demonstrate that routinely processed material is suitable for polymerase chain reaction-based analysis of translocations, although the sensitivity is reduced 10- to 100-fold, compared with fresh tissue.  相似文献   
123.
124.
125.
126.
Thirty children with acute lymphoblastic leukaemia (ALL) were studied and had a virus isolated. Only 50% produced a significant rise in complement fixing (CF) antibody titre compared to 100% of normal children. The failure to produce antibodies was unpredictable. CF antibodies are not a reliable guide to virus infections in children with ALL.  相似文献   
127.
Background: The gene encoding oestrogen receptor α (ESR1) appears to regulate bone mineral density (BMD) and other determinants of osteoporotic fracture risk.

Objective: To investigate the relation between common polymorphisms and haplotypes of the ESR1 gene and osteoporosis related phenotypes in a population based cohort of 3054 Scottish women.

Results: There was a significant association between a common haplotype "px", defined by the PvuII andXbaI restriction fragment length polymorphisms within intron 1 of the ESR1 gene, and femoral neck bone loss in postmenopausal women who had not received hormone replacement therapy (n = 945; p = 0.009). Annual rates of femoral neck bone loss were ~14% higher in subjects who carried one copy of px and 22% higher in those who carried two copies, compared with those who did not carry the px haplotype. The px haplotype was associated with lower femoral neck BMD in the postmenopausal women (p = 0.02), and with reduced calcaneal broadband ultrasound attenuation (BUA) values in the whole study population (p = 0.005). There was no association between a TA repeat polymorphism in the ESR1 promoter and any phenotype studied, though on long range haplotype analysis subjects with a smaller number of TA repeats who also carried the px haplotype had reduced BUA values.

Conclusions: The ESR1px haplotype is associated with reduced hip BMD values and increased rates of femoral neck bone loss in postmenopausal women. An association with BUA may explain the fact that ESR1 intron 1 alleles predict osteoporotic fractures by a mechanism partly independent of differences in BMD.

  相似文献   
128.
129.
Thirty two fire victims with smoke inhalation, with or without burns, and 26 control subjects had bronchoalveolar lavage performed. Cell yields and differential cell counts were assessed. All patients and controls were cigarette smokers. Patients with smoke inhalation (SI) injury generally showed higher total bronchoalveolar lavage (BAL) cell yields, and this was significant on repeat lavage from 12 patients. The increase was almost entirely due to an increase in the proportion of neutrophils in patients with smoke inhalation alone (S) and those with cutaneous burns as well as smoke inhalation (S + B). On sequential lavage of 12 patients with smoke inhalation (SI) the proportion of neutrophils had increased; this was significantly higher than on initial lavage. Using various macrophage markers, the proportions of macrophage subgroups were determined. There was an increase in UCHM1 and RFD9 positive cells in each subgroup: the increase in UCHM1 positive cells was significant in patients with burns as well as smoke inhalation, and the increase in RFD9 positive cells was significant in patients with smoke inhalation alone. Assessment of the role of such cells in the development of acute lung injury (such as adult respiratory distress syndrome) may be important in our understanding of the mechanisms entailed.  相似文献   
130.
AIMS--To compare prognostic information obtained by image analysis cytometry of paraffin wax embedded soft tissue sarcomas with conventional assessment. METHODS--A CAS 200 image analyser was used to determine DNA content of Feulgen stained cytology preparations and tissue sections and to quantify immunostaining by Ki67 and PC10 antibodies. A mitotic count in 50 high power fields was undertaken and histological grade assigned by the Trojani system. Clinical details including follow up and outcome were obtained by case note review. The Kruskal-Wallis one way analysis test, Spearman rho significance test, Kaplan-Meier method, and log-rank test were applied in statistical analysis. RESULTS--Ploidy status, DNA index, 2.5c exceeding rate, 5c exceeding rate, mitotic count and Trojani grade all correlated significantly with clinical outcome. The relation between Ki67 index and outcome did not reach significance. The PC10 index and outcome were not related. Only 2.5c exceeding rate, 5c exceeding rate, and mitotic count correlated significantly with Trojani grade. CONCLUSIONS--DNA content determination of soft tissue sarcomas by image analysis provides quantifiable information of benefit in prediction of outcome. Larger series are required to determine the independent value of ploidy. In this study quantification of anti-Ki67 and anti-PC10 immunostaining was not of prognostic benefit) by contrast with mitotic count and Trojani grade.  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