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   2128篇
  免费   81篇
  国内免费   10篇
耳鼻咽喉   11篇
儿科学   32篇
妇产科学   25篇
基础医学   336篇
口腔科学   45篇
临床医学   127篇
内科学   610篇
皮肤病学   14篇
神经病学   112篇
特种医学   93篇
外科学   296篇
综合类   17篇
预防医学   24篇
眼科学   101篇
药学   144篇
中国医学   5篇
肿瘤学   227篇
  2024年   5篇
  2023年   10篇
  2022年   29篇
  2021年   53篇
  2020年   26篇
  2019年   39篇
  2018年   33篇
  2017年   30篇
  2016年   32篇
  2015年   24篇
  2014年   49篇
  2013年   63篇
  2012年   98篇
  2011年   114篇
  2010年   79篇
  2009年   56篇
  2008年   135篇
  2007年   150篇
  2006年   127篇
  2005年   162篇
  2004年   137篇
  2003年   139篇
  2002年   167篇
  2001年   31篇
  2000年   30篇
  1999年   34篇
  1998年   64篇
  1997年   29篇
  1996年   29篇
  1995年   20篇
  1994年   26篇
  1993年   17篇
  1992年   11篇
  1991年   16篇
  1990年   11篇
  1989年   10篇
  1988年   13篇
  1987年   10篇
  1986年   11篇
  1985年   10篇
  1984年   7篇
  1983年   11篇
  1982年   6篇
  1981年   13篇
  1980年   11篇
  1979年   9篇
  1977年   4篇
  1974年   3篇
  1973年   4篇
  1966年   3篇
排序方式: 共有2219条查询结果,搜索用时 15 毫秒
11.
BACKGROUND: Apoptosis may play an important role in the development of systemic inflammatory response syndrome (SIRS) and progression to multiple organ dysfunction syndrome (MODS). To quantify the extent of apoptosis in these morbidities, we developed a sandwich ELISA system to measure serum cytochrome c (cyt-c) levels and we investigated the prognostic significance of cyt-c concentration in SIRS/MODS patients. METHODS: Cyt-c concentrations in patients with SIRS (n=53) with or at risk for MODS were measured and compared with those of control subjects (n=14). RESULTS: Cyt-c concentrations in SIRS/MODS patients increased (0.24-210 ng/ml), whereas those in control subjects were under detection limits (0.1 ng/ml). Cyt-c concentrations in non-survivors increased significantly compared with those in survivors both on the day of admission and on the fifth hospital day. A significant positive correlation was found between cyt-c concentration and two representative organ dysfunction scores, APACHE II and multi-organ failure (MOF) score. Cyt-c concentrations increased earlier than MOF score during the exacerbation phase and rapidly decreased during the convalescence phase in a survivor, but the level continued to be high in a non-survivor. CONCLUSIONS: Determination of serum cyt-c concentrations may be useful to assess the severity of organ dysfunction and to predict the prognosis of SIRS/MODS patients.  相似文献   
12.
The impact of changes in nutritional status during hospitalization on prognosis in patients with heart failure with preserved ejection fraction (HFpEF) remains unknown. We examined the association between changes in the Geriatric Nutritional Risk Index (GNRI) and prognosis during hospitalization in patients with HFpEF stratified by nutritional status on admission. Nutritional status did and did not worsen in 348 and 349 of 697 patients with high GNRI on admission, and in 142 and 143 of 285 patients with low GNRI on admission, respectively. Kaplan–Meier analysis revealed no difference in risk of the composite endpoint, all-cause death, or heart failure admission between patients with high GNRI on admission whose nutritional status did and did not worsen. In contrast, patients with low GNRI on admission whose nutritional status did not worsen had a significantly lower risk of the composite endpoint and all-cause death than those who did. Multivariable analysis revealed that worsening nutritional status was independently associated with a higher risk of the composite endpoint and all-cause mortality in patients with low GNRI on admission. Changes in nutritional status during hospitalization were thus associated with prognosis in patients with malnutrition on admission, but not in patients without malnutrition among those with HFpEF.  相似文献   
13.
Massive hemoptysis is a fatal complication associated with pulmonary tuberculosis (TB). It can lead to severe respiratory failure. Extracorporeal membrane oxygenation (ECMO) is a life-saving technology that is rarely indicated for bleeding disorders. We herein report a 26-year-old man who presented with severe respiratory failure caused by massive hemoptysis with pulmonary TB. Transcatheter artery embolization was successfully performed with venovenous ECMO support. The hemostatic procedure allowed concomitant anticoagulant use, and neither bleeding nor thrombotic complications occurred throughout the clinical course. Administering the appropriate hemostatic procedure with subsequent management, including anticoagulant therapy, supported ECMO application in a case of bleeding.  相似文献   
14.
15.
The effect of treatment with favipiravir, an antiviral purine nucleoside analog, for coronavirus disease 2019 (COVID-19) on the production and duration of neutralizing antibodies for SARS-CoV-2 was explored. There were 17 age-, gender-, and body mass index-matched pairs of favipiravir treated versus control selected from a total of 99 patients recovered from moderate COVID-19. These subjects participated in the longitudinal (>6 months) analysis of (i) SARS-CoV-2 spike protein’s receptor-binding domain IgG, (ii) virus neutralization assay using authentic virus, and (iii) neutralization potency against original (WT) SARS-CoV-2 and cross-neutralization against B.1.351 (beta) variant carrying triple mutations of K417N, E484K, and N501Y. The results demonstrate that the use of favipiravir: (1) significantly accelerated the elimination of SARS-CoV-2 in the case vs. control groups (p = 0.027), (2) preserved the generation and persistence of neutralizing antibodies in the host, and (3) did not interfere the maturation of neutralizing potency of anti-SARS-CoV-2 and neutralizing breadth against SARS-CoV-2 variants. In conclusion, treatment of COVID-19 with favipiravir accelerates viral clearance and does not interfere the generation or maturation of neutralizing potency against both WT SARS-CoV-2 and its variants.  相似文献   
16.
Polysomnographic findings and clinical symptoms were investigated in 14 cases of upper airway resistance syndrome. The mean scores of the Epworth sleepiness scale and self-rating depression scale in eight cases were 13.5 and 38.6, respectively. The mean sleep latency of the multiple sleep latency test in four cases was 10.2 min. Seven cases were treated with continuous positive airway pressure (CPAP), and one with hormone replacement therapy. The most common symptom was daytime sleepiness. Five cases had hypertension. CPAP reduced increasing negative esophageal pressure (Pes) and frequency of EEG arousals, and improved hypertension in one case. Hormone replacement therapy ameliorated increasing negative Pes and clinical symptoms.  相似文献   
17.
18.
To diagnose visceral leishmaniasis (kala-azar), we have developed a nested PCR method based on amplification of the mini-exon gene, which is unique and tandomly repeated in the Leishmania genome. Nested PCR was sufficiently sensitive for the detection of DNA in an amount equivalent to a single Leishmania parasite or less. We examined the usefulness of this PCR method using bone marrow aspirates and buffy coat cells collected from kala-azar patients who had or had not received chemotherapy in northwest China. We obtained PCR positivity for all of the parasitologically positive bone marrow samples from the patients. Some ambiguities with the primary PCR results were eliminated by the subsequent nested PCR. The buffy coat samples from 7 of 12 patients with splenomegaly were positive by the nested PCR, although only 2 of them were positive for parasites by culture. However, buffy coat samples from nine children, whose splenomegaly has been reduced and clinically cured by antimony treatment, were all negative. Thus, this nested PCR method represents a new tool for the diagnosis of kala-azar with patient blood samples instead of bone marrow or spleen aspirates obtained by more invasive procedures.  相似文献   
19.
This study assessed the antimalarial activity of dipyridamole, a well-known vasodilator and inhibitor of platelet aggregation. Dipyridamole was effective against all of the erythrocytic stages such as rings, trophozoites and schizonts, and induced ultrastructural changes during the transition from trophozoite to schizont in vitro. Merozoites were also inhibited from invading dipyridamole-treated erythrocytes. It seems that dipyridamole binds to the erythrocyte membrane blocking the receptors for the merozoite. The 50% inhibitory concentration (IC(50)) of dipyridamole against Plasmodium falciparum infection was 30 nM. The IC(50) of chloroquine decreased from 97.0 nM to 13.7 nM when combined with dipyridamole (0.1 nM). Therefore, we suggest that dipyridamole has antiplasmodial activity due to its ability to arrest parasite development and by inhibiting merozoite invasion of the erythrocytes. Chloroquine activity against P. falciparum is also enhanced by the addition of dipyridamole. Treatment with a combination of chloroquine and dipyridamole may lead to a more effective treatment for chloroquine-resistant strains of P. falciparum.  相似文献   
20.
We carried out electron microscopic studies on renal tissues from 9 patients with IgA nephropathy. Electron dense deposits were present in the mesangial area in all cases, subendothelial deposits in 4, and subepithelial deposits in only one. In basement membrane, segmental swelling and rarefaction of basement membrane substance were observed. In some cases the degenerated basement membrane substance protruded through the dilated endothelial fenestration into capillary lumina. Focal splitting, attenuation, mouse eaten appearance, and herniation of basement membrane were seen in a high incidence. Mesangial cells possessed well developed rough endoplasmic reticulums and polysomes. In the peripheral areas of mesangial cell cytoplasm, there was accumulation of electron dense substance and this was occasionally continuously present in the mesangial matrix. There was segmental swelling of endothelial cell cytoplasm, resulting in loss of fenestration. Epithelial cells had well developed rough endoplasmic reticulums and polysomes. Segmental foot process fusion was seen, and these processes, regardless of fusion, became electron denser in the area close to the basement membrane. Multivesiculated bodies were present in all cases in the epithelial cells and in 7 cases in the endothelial cells. Spherical microparticles were present in 3 cases in the urinary space or between the basement membrane and the epithelial cells.  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