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   1469篇
  免费   122篇
  国内免费   7篇
耳鼻咽喉   18篇
儿科学   35篇
妇产科学   37篇
基础医学   199篇
口腔科学   44篇
临床医学   152篇
内科学   321篇
皮肤病学   19篇
神经病学   52篇
特种医学   99篇
外科学   198篇
综合类   25篇
一般理论   1篇
预防医学   44篇
眼科学   43篇
药学   78篇
中国医学   5篇
肿瘤学   228篇
  2023年   5篇
  2022年   9篇
  2021年   31篇
  2020年   16篇
  2019年   26篇
  2018年   46篇
  2017年   32篇
  2016年   33篇
  2015年   31篇
  2014年   45篇
  2013年   69篇
  2012年   84篇
  2011年   72篇
  2010年   56篇
  2009年   36篇
  2008年   66篇
  2007年   83篇
  2006年   64篇
  2005年   60篇
  2004年   68篇
  2003年   55篇
  2002年   55篇
  2001年   47篇
  2000年   47篇
  1999年   35篇
  1998年   26篇
  1997年   24篇
  1996年   20篇
  1995年   25篇
  1994年   20篇
  1993年   23篇
  1992年   34篇
  1991年   34篇
  1990年   30篇
  1989年   24篇
  1988年   25篇
  1987年   19篇
  1986年   15篇
  1985年   22篇
  1984年   12篇
  1983年   10篇
  1982年   12篇
  1981年   8篇
  1980年   9篇
  1978年   8篇
  1977年   5篇
  1976年   5篇
  1972年   5篇
  1970年   3篇
  1967年   2篇
排序方式: 共有1598条查询结果,搜索用时 11 毫秒
11.
Coxsackievirus B3 (CVB3) infection can result in myocarditis, which in turn may lead to a protracted immune response and subsequent dilated cardiomyopathy. Human decay-accelerating factor (DAF), a binding receptor for CVB3, was synthesized as a soluble IgG1-Fc fusion protein (DAF-Fc). In vitro, DAF-Fc was able to inhibit complement activity and block infection by CVB3, although blockade of infection varied widely among strains of CVB3. To determine the effects of DAF-Fc in vivo, 40 adolescent A/J mice were infected with a myopathic strain of CVB3 and given DAF-Fc treatment 3 days before infection, during infection, or 3 days after infection; the mice were compared with virus alone and sham-infected animals. Sections of heart, spleen, kidney, pancreas, and liver were stained with hematoxylin and eosin and submitted to in situ hybridization for both positive-strand and negative-strand viral RNA to determine the extent of myocarditis and viral infection, respectively. Salient histopathologic features, including myocardial lesion area, cell death, calcification and inflammatory cell infiltration, pancreatitis, and hepatitis were scored without knowledge of the experimental groups. DAF-Fc treatment of mice either preceding or concurrent with CVB3 infection resulted in a significant decrease in myocardial lesion area and cell death and a reduction in the presence of viral RNA. All DAF-Fc treatment groups had reduced infectious CVB3 recoverable from the heart after infection. DAF-Fc may be a novel therapeutic agent for active myocarditis and acute dilated cardiomyopathy if given early in the infectious period, although more studies are needed to determine its mechanism and efficacy.  相似文献   
12.
BACKGROUND: Some cases of recurrent miscarriage have a thrombotic basis. Thromboelastography is a rapid, reproducible test of whole-blood haemostasis. METHODS: Thromboelastography was performed in 494 consecutive, non-pregnant women (median age 35 years; range 21-48) with a history of miscarriages at <12 weeks gestation (median 4; range 3-12) and 55 parous women (median age 33 years; range 20-41) with no history of pregnancy loss. The prospective outcome of untreated pregnancies amongst 108 women with recurrent miscarriage was studied. RESULTS: The maximum clot amplitude (MA) (median 66.0 mm; range 48.0-76.0) was significantly higher and the rate of clot lysis (LY30) (median 2.5%; range 0.5-7.8) significantly lower amongst women with recurrent miscarriage compared with controls (MA 61.5 mm; range 50.0-67.0; P = 0.01; LY30 4.9%; range 2.9-9.7; P = 0.01). The pre-pregnancy MA was significantly higher amongst women who subsequently miscarried (median 66.0 mm; range 54.0-73.0) compared with those whose had a live birth (median 61.7 mm; 48.0-71.5; P < 0.01). A pre-pregnancy MA >or=64 mm has a sensitivity of 68% and specificity of 82% to predict miscarriage. CONCLUSIONS: Thromboelastography identifies a subgroup of women with recurrent miscarriage to be in a prothrombotic state outside of pregnancy. Women in such a state are at increased risk of miscarriage in future untreated pregnancies.  相似文献   
13.
The presence of checkpoint mechanisms which are able to recognize damaged chromatin and thereafter to prevent exit from metaphase I has been investigated in giant mouse oocytes produced by fusion of a normal metaphase I oocyte with an equivalent oocyte with damaged chromatin. The presence of damaged chromatin did not prevent the onset of anaphase I in both sets of chromatin in the fused cells. Interestingly, fused or unfused cells containing only damaged chromatin failed to enter anaphase and persisted instead in a metaphase-like state. These results demonstrate the fragility of checkpoint controls in mammalian female germ cells.   相似文献   
14.
15.
Lower incidence and mortality rates from prostate cancer(PCa)have been shown in Asian men in general compared to Westerners.This is the first study detailing th...  相似文献   
16.
The N-acetyl-beta-glucosaminidase activity in hydatidiform mole is two-fold higher than that in full-term placenta. Qualitatively, the enzymes from the two tissues are similar with respect to KM values and pH optima. Both enzymes also contain a new isoenzyme form detectable by polyacrylamide gel electrophoresis. However, the molar enzyme is more susceptible to heat denaturation, presumably due to the presence of a higher level of the heat-labile isoenzyme form A in this tissue. Data are also presented incicating that the placenta is not the source of the N-acetyl-beta-glucosaminidase activity in maternal serum.  相似文献   
17.
18.
Histone deacetylase inhibitors (HDACi) developed as anti-cancer agents have a high degree of selectivity for killing cancer cells. HDACi induce acetylation of histones and nonhistone proteins, which affect gene expression, cell cycle progression, cell migration, and cell death. The mechanism of the tumor selective action of HDACi is unclear. Here, we show that the HDACi, vorinostat (Suberoylanilide hydroxamic acid, SAHA), induces DNA double-strand breaks (DSBs) in normal (HFS) and cancer (LNCaP, A549) cells. Normal cells in contrast to cancer cells repair the DSBs despite continued culture with vorinostat. In transformed cells, phosphorylated H2AX (γH2AX), a marker of DNA DSBs, levels increased with continued culture with vorinostat, whereas in normal cells, this marker decreased with time. Vorinostat induced the accumulation of acetylated histones within 30 min, which could alter chromatin structure-exposing DNA to damage. After a 24-h culture of cells with vorinostat, and reculture without the HDACi, γH2AX was undetectable by 2 h in normal cells, while persisting in transformed cells for the duration of culture. Further, we found that vorinostat suppressed DNA DSB repair proteins, e.g., RAD50, MRE11, in cancer but not normal cells. Thus, the HDACi, vorinostat, induces DNA damage which normal but not cancer cells can repair. This DNA damage is associated with cancer cell death. These findings can explain, in part, the selectivity of vorinostat in causing cancer cell death at concentrations that cause little or no normal cell death.  相似文献   
19.
Competing demands for scarce healthcare resources have accentuatedthe requirement for routine clinical practice to be evidence-based.One of the benchmarks for evidence-based medicine is the appropriatelyconducted randomized controlled trial (RCT). Although epidemiologicalstudies, whether case–control or cohort in design, havecontributed enormously to the generation of hypotheses and permitthe controlled evaluation of therapeutic interventions, theyare susceptible to biases through selection, information ascertainmentand confounding. While RCTs are also susceptible to such biases,the process of randomization and of blinded evaluation of outcomespermits the closest approximation in clinical research to theconduct of a hypothesis-testing laboratory experiment. Historically,there have been several obstacles to the execution of high-qualityRCTs to address important rheumatological questions. One  相似文献   
20.
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