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   181700篇
  免费   1188篇
  国内免费   40篇
耳鼻咽喉   1176篇
儿科学   6820篇
妇产科学   3123篇
基础医学   17296篇
口腔科学   1675篇
临床医学   12724篇
内科学   32201篇
皮肤病学   779篇
神经病学   16750篇
特种医学   9168篇
外科学   29895篇
综合类   2341篇
预防医学   18200篇
眼科学   2909篇
药学   10082篇
中国医学   674篇
肿瘤学   17115篇
  2023年   38篇
  2021年   142篇
  2020年   86篇
  2019年   147篇
  2018年   22053篇
  2017年   17459篇
  2016年   19629篇
  2015年   1052篇
  2014年   975篇
  2013年   970篇
  2012年   7241篇
  2011年   21330篇
  2010年   18985篇
  2009年   11647篇
  2008年   19730篇
  2007年   21979篇
  2006年   831篇
  2005年   2496篇
  2004年   3693篇
  2003年   4615篇
  2002年   2770篇
  2001年   470篇
  2000年   618篇
  1999年   358篇
  1998年   251篇
  1997年   276篇
  1996年   145篇
  1995年   164篇
  1994年   136篇
  1993年   97篇
  1992年   173篇
  1991年   202篇
  1990年   262篇
  1989年   195篇
  1988年   166篇
  1987年   151篇
  1986年   144篇
  1985年   110篇
  1984年   103篇
  1983年   80篇
  1982年   51篇
  1980年   59篇
  1979年   59篇
  1974年   47篇
  1970年   56篇
  1969年   39篇
  1968年   40篇
  1938年   60篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Purpose

JWH-424, (8-bromo-1-naphthyl)(1-pentyl-1H-indol-3-yl)methanone, is a synthetic cannabinoid, which is a brominated analogue of JWH-018, one of the best-known synthetic cannabinoids. Despite the structural similarity to JWH-018, little is known about JWH-424 including its metabolism. The aim of the study was to compare human liver microsomes (HLM) and the fungus Cunninghamella elegans as the metabolism catalysts for JWH-424 to better understand the characteristic actions of the fungus in the synthetic cannabinoid metabolism.

Methods

JWH-424 was incubated with HLM for 1 h and Cunninghamella elegans for up to 72 h. The HLM incubation mixtures were diluted with methanol and fungal incubation mixtures were extracted with dichloromethane and reconstituted in methanol before analyses by liquid chromatography–high-resolution mass spectrometry (LC-HRMS).

Results

HLM incubation resulted in production of ten metabolites through dihydrodiol formation, hydroxylation, and/or ipso substitution of the bromine with a hydroxy group. Fungal incubation led to production of 23 metabolites through carboxylation, dihydrodiol formation, hydroxylation, ketone formation, glucosidation and/or sulfation.

Conclusions

Generally, HLM models give good predictions of human metabolites and structural analogues are metabolised in a similar fashion. However, major hydroxy metabolites produced by HLM were those hydroxylated at naphthalene instead of pentyl moiety, the major site of hydroxylation for JWH-018. Fungal metabolites, on the other hand, had undergone hydroxylation mainly at pentyl moiety. The metabolic disagreement suggests the necessity to verify the human metabolites in authentic urine samples, while H9 and H10 (hydroxynaphthalene), H8 (ipso substitution), F22 (hydroxypentyl), and F17 (dihydroxypentyl) are recommended for monitoring of JWH-424 in urinalysis.

  相似文献   
2.
3.
4.
Candida blood stream infection (candidemia) is severe systemic infection mainly develops after intensive medical cares. The mortality of candidemia is affected by the underlying conditions, causative agents and the initial management. We retrospectively analyzed mortality-related risk factors in cases of candidemia between April 2011 and March 2016 in five regional hospitals in Japan. We conducted bivariate and multivariate analysis of factors including causative Candida species, patients' predisposing conditions, and treatment strategies, such as empirically selected antifungal drug and time to appropriate antifungal treatment, to elucidate their effects on 30-day mortality. The study enrolled 289 cases of candidemia in adults. Overall 30-day mortality was 27.7%. Forty-nine cases (17.0%) were community-acquired. Bivariate analysis found advanced age, high Sequential Organ Failure Assessment (SOFA) score, and prior antibiotics use as risk factors for high mortality; however community-acquired candidemia, C. parapsilosis candidemia, obtaining follow-up blood culture, and empiric treatment with fluconazole were associated with low mortality. Logistic regression revealed age ≥65 years (adjusted odds ratio, 2.13) and sequential organ failure assessment (SOFA) score ≥6 (6.30) as risk factors for 30-day mortality. In contrast, obtaining follow-up blood culture (0.38) and empiric treatment with fluconazole (0.32) were found to be protective factors. The cases with candidemia in associated with advanced age and poor general health conditions should be closely monitored. Obtaining follow-up blood culture contributed to an improved prognosis.  相似文献   
5.
6.
BackgroundCarpal tunnel syndrome is the most common compression syndrome of the peripheral nerve. Transthyretin amyloidosis and dialysis-related β2-microglobulin amyloidosis are known causes of carpal tunnel syndrome.Case ReportA Japanese woman showed carpal tunnel syndrome 16 years after a domino liver transplantation (DLT) from the donor with hereditary transthyretin amyloidosis. DLT indication was congenital extrahepatic portosystemic shunt, and the patient had been put on maintenance hemodialysis because of chronic kidney disease 6 years before DLT. Moreover, the amyloid precursor protein of the patient was histologically confirmed not to be β2-microglobulin, but transthyretin.ConclusionsThe existence of amyloid was speculated when the patient who underwent DLT from hereditary transthyretin amyloidosis showed carpal tunnel syndrome. Additionally, elucidating the amyloid precursor protein when the patient has another cause of amyloidosis is necessary.  相似文献   
7.
8.
BackgroundTazemetostat is a selective and orally available inhibitor of enhancer of zeste homolog 2 (EZH2), a histone methyltransferase and epigenetic regulator of cellular differentiation programs. We carried out a phase I study of tazemetostat in Japanese patients with relapsed or refractory B‐cell non‐Hodgkin‐type lymphoma (B‐NHL) to evaluate its tolerability, safety, pharmacokinetics, and preliminary antitumor activity.MethodsTazemetostat was given orally at a single dose of 800 mg on the first day and 800 mg twice daily (BID: total 1600 mg/d) on following days in a 28‐day/cycle manner. Tazemetostat dose‐limiting toxicity (DLT) was evaluated up to the end of the first treatment cycle. Archival tumor tissues were analyzed for hotspot EZH2 mutations.ResultsAs of 15 January 2018, seven patients (four follicular lymphoma [FL] and three diffuse large B‐cell lymphoma [DLBCL]) were enrolled. The median age was 73 (range, 59‐85) years, and the median number of prior chemotherapy regimens was three (range, one to five). No DLT was observed (one patient was not evaluable due to early disease progression). The common treatment‐related adverse events (AEs) were thrombocytopenia and dysgeusia (three patients each; 42.9%). No treatment‐related serious AEs were observed. The objective response rate was 57% (4/7 patients), including responses in three of four patients with FL and one of three patients with DLBCL. An EZH2 mutation was detected in one patient with FL responding to treatment.ConclusionsTazemetostat at 800 mg BID showed an acceptable safety profile and promising antitumor activity in Japanese patients with relapsed or refractory B‐NHL.  相似文献   
9.
10.
Signal regulatory protein alpha (SIRPα) is a type I transmembrane protein that inhibits macrophage phagocytosis of tumor cells upon interaction with CD47, and the CD47-SIRPα pathway acts as an immune checkpoint factor in cancers. This study aims to clarify the clinical significance of SIRPα expression in esophageal squamous cell carcinoma (ESCC). First, we assessed SIRPα expression using RNA sequencing data of 95 ESCC tissues from The Cancer Genome Atlas (TCGA) and immunohistochemical analytic data from our cohort of 131 patients with ESCC. Next, we investigated the correlation of SIRPα expression with clinicopathological factors, patient survival, infiltration of tumor immune cells, and expression of programmed cell death-ligand 1 (PD-L1). Overall survival was significantly poorer with high SIRPα expression than with low expression in both TCGA and our patient cohort (P < .001 and P = .027, respectively). High SIRPα expression was associated with greater depth of tumor invasion (P = .0017). Expression of SIRPα was also significantly correlated with the tumor infiltration of M1 macrophages, M2 macrophages, CD8+ T cells, and PD-L1 expression (P < .001, P < .001, P = .03, and P < .001, respectively). Moreover, patients with SIRPα/PD-L1 coexpression tended to have a worse prognosis than patients with expression of either protein alone or neither. Taken together, SIRPα indicates poor prognosis in ESCC, possibly through inhibiting macrophage phagocytosis of tumor cells and inducing suppression of antitumor immunity. Signal regulatory protein alpha should be considered as a potential therapeutic target in ESCC, especially if combined with PD-1-PD-L1 blockade.  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