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   9407篇
  免费   470篇
  国内免费   60篇
耳鼻咽喉   107篇
儿科学   121篇
妇产科学   120篇
基础医学   1102篇
口腔科学   168篇
临床医学   618篇
内科学   2392篇
皮肤病学   148篇
神经病学   673篇
特种医学   351篇
外科学   2003篇
综合类   48篇
预防医学   248篇
眼科学   85篇
药学   709篇
中国医学   19篇
肿瘤学   1025篇
  2023年   53篇
  2022年   94篇
  2021年   224篇
  2020年   123篇
  2019年   183篇
  2018年   210篇
  2017年   199篇
  2016年   218篇
  2015年   216篇
  2014年   271篇
  2013年   357篇
  2012年   512篇
  2011年   622篇
  2010年   334篇
  2009年   312篇
  2008年   506篇
  2007年   570篇
  2006年   543篇
  2005年   547篇
  2004年   562篇
  2003年   537篇
  2002年   538篇
  2001年   153篇
  2000年   156篇
  1999年   169篇
  1998年   129篇
  1997年   89篇
  1996年   92篇
  1995年   84篇
  1994年   76篇
  1993年   65篇
  1992年   120篇
  1991年   81篇
  1990年   102篇
  1989年   97篇
  1988年   97篇
  1987年   93篇
  1986年   91篇
  1985年   70篇
  1984年   60篇
  1983年   38篇
  1982年   22篇
  1980年   20篇
  1979年   35篇
  1978年   29篇
  1976年   20篇
  1975年   20篇
  1974年   27篇
  1973年   18篇
  1968年   18篇
排序方式: 共有9937条查询结果,搜索用时 906 毫秒
991.
Invasion of antigens through the mucosal surface can be prevented by the common mucosal immune system, including Peyer's patches (PPs) and nasopharyngeal-associated lymphoreticular tissue (NALT). The adenoids (nasopharyngeal tonsils) comprise one of the NALTs and constitute the major part of Waldeyer's lymphoid ring in humans. However, the role of the lymphoepithelium, including M cells and dendritic cells (DCs), in the adenoids is unknown compared with the epithelium of PPs. NALTs also have unique functions such as the barrier of epithelial cells and uptake of antigens by M cells and DCs, and may play a crucial role in airway mucosal immune responses. The lymphoepithelium of adenoids has well-developed tight junctions that play an important role in the barrier function, the same as nasal epithelium but not palatine tonsillar epithelium. Tight junction molecules are expressed in both M cells and DCs as well as epithelial cells, and various antigens may be sampled, transported, and released to lymphocytes through the cells while they maintain the integrity of the epithelial barrier. This review summarizes the recent progress in our understanding of how M cells and DCs control the epithelial barrier in the adenoids.  相似文献   
992.
Tissue characterization of plaques of coronary arteries is important to clarify the process of acute coronary syndrome and prevent it. The purpose of this study is to develop an online integrated backscatter intravascular ultrasound (IB-IVUS) system and validate the diagnostic accuracy for the characterization of coronary plaques. A personal computer equipped with custom software was connected to an IVUS imaging system. Images were acquired from 242 segments of 46 coronary arteries from 25 cadavers obtained at autopsy. In the training study, a total of 724 regions-of-interests on color-coded maps were compared with histologic images. In the validation study, a total of 192 cross-sections of coronary arteries were evaluated. Receiver operating characteristic curve analysis showed that the cut-off points of -49 dB (area under curve = 0.98) and -29 dB (area under curve = 0.99) were the most reliable predictors of lipid pools, fibrosis and calcification. In the validation study, the analysis using IB values classified fibrous, lipid-rich and fibrocalcific plaque components with a high accuracy of 93%, 90% and 96%, respectively. The overall agreement between histologic and IB-IVUS diagnoses (n = 175) was high (Cohen's kappa = 0.81). The IB-IVUS system provides high diagnostic accuracy for analysis of tissue characteristics of coronary plaques.  相似文献   
993.
994.
To improve the selection of donors for allogeneic stem cell transplantation, it is important to identify reliable parameters that predict CD34+-cell yields after granulocyte-colony stimulating factor (G-CSF)-induced peripheral blood stem cell (PBSC) mobilization. We retrospectively investigated the peripheral blood (PB) kinetics of white blood cells (WBCs), CD34+ cells, matrix metalloproteinases (MMP)-9 and -2, and tissue inhibitors of metalloproteinases (TIMP)-1 and -2 in 15 healthy donors during their treatment with G-CSF. All donors received 10 microg/kg of recombinant human G-CSF once a day subcutaneously. Leukapheresis was initiated after 4 days of G-CSF treatment, and G-CSF treatment continued until the last day of leukapheresis. WBC and CD34+ cell numbers in the PB rose after 2 and 3 or 4 days of G-CSF treatment, respectively. The PB CD34+ cell numbers on day 4 correlated weakly with the increase in WBC counts from day 1 to day 2 (R(2) = 0.254, P = 0.056). There were also positive correlations between the CD34+ cell numbers in the PBSC products on day 4 and the CD34+ cells in the PB on days 1 and 4 (R(2) = 0.768, P < 0.0001 and R(2) = 0.816, P < 0.0005, respectively). The MMP-9 plasma levels on days 1 and 4 also correlated positively with the day 4 circulating CD34+ cell numbers (R(2) = 0.393, P < 0.05 and R(2) = 0.406, P = 0.01, respectively). In conclusion, the CD34+ cell numbers in the PB steady state may be a useful parameter selecting allogeneic PBSC donors.  相似文献   
995.
The G-protein β3 subunit (GNB3) gene is a key modulator of signal transduction and is a major candidate for SSRIs response. The aim of the present study is to test a possible effect of the C825T polymorphism on the antidepressant response and intolerance to selective serotonin reuptake inhibitors (SSRIs) in 146 Japanese samples with major depression treated with paroxetine or fluvoxamine for 6 weeks. The severity of depression symptom was assessed using the 21-item Hamilton Rating Scale for Depression (HAM-D) and adverse drug reactions were evaluated bi-weekly. No association with SSRIs treatment response was observed in 107 completers also including HAM-D baseline scores, SSRI type or/and 5-HTTLPR variants in the model as covariates. Furthermore, no significant association could be observed with intolerance to SSRIs in the whole subjects. The result suggests that C825T variants of GNB3 cannot play a major role as a predictor of treatment response as well as intolerance to SSRIs in Japanese patients with major depression.  相似文献   
996.
BACKGROUND: Recent studies indicate that the traditional Japanese herbal medicine yi-gan san (YGS, yokukan-san in Japanese), a serotonin modulator, may be safe and useful in treating behavioral and psychological symptoms in dementia and borderline personality disorder patients. The authors examined the efficacy, tolerability, and safety of YGS in patients with tardive dyskinesia. METHODS: Twenty-two patients with schizophrenia who had neuroleptic-induced tardive dyskinesia were given 7.5 g/day of YGS for 12 weeks in an open-label study. RESULTS: Administration of YGS resulted in a statistically significant improvement in tardive dyskinesia and psychotic symptoms. CONCLUSIONS: YGS may be an effective and safe therapy to control tardive dyskinesia and psychosis in patients with schizophrenia, that should be further tested in double-blind, placebo-controlled trials.  相似文献   
997.
998.
999.
This study compared the D(2) partial agonists, aripiprazole, (R(+)-terguride; S(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [S(-)-3-PPP]; 7-[3-[4-(2,3-dimethylphenyl)piperazinyl]propoxy]-2(1H)-quinolinone [OPC-4392]) and D(2) antagonists (haloperidol, olanzapine, clozapine, risperidone, and quetiapine) on prepulse inhibition (PPI) of the startle response, and the ability to reverse apomorphine-induced deficits in the PPI response. Aripiprazole did not essentially affect PPI in na?ve rats but dose-dependently restored apomorphine-induced PPI disruption. R(+)-terguride restored PPI disruption but suppressed PPI significantly in na?ve rats, S(-)-3-PPP partially restored whereas OPC-4392 did not restore PPI disruption. Haloperidol and risperidone restored PPI disruption whereas olanzapine and quetiapine partially restored PPI disruption and clozapine had no restorative effect. In conclusion, aripiprazole, unlike other antipsychotic agents, failed to suppress PPI significantly and restored PPI disruption.  相似文献   
1000.
We genetically screened patients with ataxia with ocular motor apraxia type 1 (AOA1)/early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH), with a Japanese variant form of Friedreich's ataxia. Three patients were found to have a homozygous insertion mutation of the aprataxin gene (689insT). An elder sister of a patient in this series died of cerebral hemorrhage at the age of 45, and underwent autopsy. In her cerebellar cortex, the mean density of Purkinje cells in the flocculus had predominantly decreased to 6.7% of normal controls, whereas the Purkinje cells in the other areas of the cerebellar hemisphere had decreased to 78.2%. This suggests that the cerebellar flocculus is the primary affected lesion in AOA1/EAOH, which should be associated with ocular motor apraxia.  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