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   18243篇
  免费   1556篇
  国内免费   1407篇
耳鼻咽喉   209篇
儿科学   190篇
妇产科学   207篇
基础医学   2036篇
口腔科学   343篇
临床医学   2396篇
内科学   2764篇
皮肤病学   123篇
神经病学   957篇
特种医学   545篇
外国民族医学   16篇
外科学   1926篇
综合类   3339篇
现状与发展   5篇
一般理论   5篇
预防医学   1197篇
眼科学   430篇
药学   1934篇
  4篇
中国医学   910篇
肿瘤学   1670篇
  2024年   44篇
  2023年   292篇
  2022年   717篇
  2021年   869篇
  2020年   698篇
  2019年   602篇
  2018年   649篇
  2017年   610篇
  2016年   579篇
  2015年   852篇
  2014年   1021篇
  2013年   842篇
  2012年   1276篇
  2011年   1542篇
  2010年   968篇
  2009年   721篇
  2008年   894篇
  2007年   991篇
  2006年   955篇
  2005年   939篇
  2004年   664篇
  2003年   612篇
  2002年   550篇
  2001年   479篇
  2000年   425篇
  1999年   427篇
  1998年   300篇
  1997年   312篇
  1996年   218篇
  1995年   222篇
  1994年   166篇
  1993年   121篇
  1992年   127篇
  1991年   101篇
  1990年   83篇
  1989年   68篇
  1988年   81篇
  1987年   57篇
  1986年   46篇
  1985年   32篇
  1984年   18篇
  1983年   9篇
  1982年   7篇
  1981年   7篇
  1980年   6篇
  1979年   7篇
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
1.
人体蠕形螨的生物学研究   总被引:4,自引:0,他引:4  
用透明胶带法观察蠕形螨在人体面部的寄生、逸出及其在体外的存活能力。结果表明:毛囊蠕形螨(Demod-exfoliculorum,D.f.)主要以颚体朝向毛囊底部寄生,且常常有多条群居现象,而皮脂蠕形螨,(Demodexbrevis,D.b.)一般为单条独居生活。两种人体蠕形螨昼夜均可主动爬出毛囊口出现在皮肤表面,D.f.以白天1000~1800为逸出高峰;D.b.则以夜间2200~200逸出最多。此外,蠕形螨在体外有较强的活动力和存活力。透明胶带法在人体蠕形螨的流行病学调查和生物学研究方面具有较高的应用价值  相似文献   
2.
OBJECTIVE: Outcomes analysis in congenital diaphragmatic hernia (CDH) requires a validated risk-adjustment tool. The purpose of this study was to use the Canadian Neonatal Network (CNN) database to validate the Score for Neonatal Acute Physiology, Version II (SNAP-II) for prediction of mortality among CDH infants admitted to a neonatal intensive care unit (NICU), and to compare this to the predictive equation recently developed by the Congenital Diaphragmatic Hernia Study Group (CDHSG). STUDY DESIGN: Infants with CDH in the CNN database were identified. Bivariate and multivariable logistic regression models were used to identify risk factors predictive of mortality. Model predictive performance and calibration were assessed using the area under the receiver operator characteristic curve and the technique of Hosmer-Lemeshow, respectively, and compared with the CDHSG predictive equation. RESULTS: There were 88 patients with CDH among 19,507 admissions to CNN hospitals. The mortality rate among CDH patients surviving to NICU admission was 17%, and 12.5% received extracorporeal membrane oxygenation therapy. Gestational age and admission SNAP-II score predicted mortality. Model predictive performance and calibration were optimized with these variables combined. The CDHSG equation was equally predictive of mortality, but was only marginally calibrated. CONCLUSIONS: SNAP-II is highly predictive of mortality among patients with CDH, and can be used to risk-adjust these patients.  相似文献   
3.
4.
5.
Twenty cases of microglandular hyperplasia (MGH) of the uterine cervix and 14 cases of low-grade (nuclear) mucinous adenocarcinoma of the endometrium (MA) were compared morphologically and immunohistochemically. Subnuclear vacuoles were seen in 10 cases of MGH but were absent in all MA. Luminal squamous metaplasia was seen in only 10% of MGH cases versus 65% of MA cases. Stromal foam cells were present in 36% of MA but were absent in MGH cases. Both MGH and MA had minimal variation in nuclear size and inconspicuous nucleoli. As many as 8 mitoses/10 high-power fields (MF/10 HPF) were found in MA compared with 3 or fewer MF/10 HPF in MGH. Vimentin was expressed in 90% of MA but was absent in MGH. A significantly higher percentage of MA cells stained with MIB-1 than did those of MGH (mean 11% versus 0.5%). Both MA and MGH lacked CEA and p53 staining, whereas both had variable expression of ER and PR with no significant differences except that PR was absent in 40% of MGH cases. Our findings indicate that in the differential diagnosis of MGH versus MA, the presence of subnuclear vacuoles favors the former, whereas luminal squamous metaplasia, stromal foam cells, mitotic activity, vimentin expression, and MIB-1 expression favor the latter.  相似文献   
6.
OBJECTIVE: To examine the distribution of rat facial motoneurons contributing different branches under normal situation and when nerve reinnervation occurred following facial nerve axotomy. METHODS: The normal distribution of motoneurons innervated both buccal and marginal mandibular branches and its reorganization after facial nerve reinnervation was observed using retrograde labeling with fluorescein. RESULTS: Under normal situation, the motoneurons contributing buccall and marginal mandibular branches were primarily distributed in the intermedial and lateral subnucleus in facial nucleus and almost completely overlapped. The two types labeled neurons organized closely, but there were no double-labeled neurons. Although the motoneurons contributing buccall and marginal mandibular branches were primarily overlapped 4 month post-anastomosis, the number of the labeled neurons obviously decreased and the organization got more scattered. There were 10% of buccall branches, 5% of marginal mandibular motoneurons in the dorsal subnuleus, 1% of buccall and 4% of marginal mandibular in dorsal ventral and medial subnucleus. The distribution pattern of the motoneurons 6 month post-anastomosis was similar to that of 4 month post-anastomosis, but the number of the labeled neurons increased, and there were 1%-2% double-labeled neurons. CONCLUSION: The distribution pattern of motoneurons innervated both buccal and marginal mandibular branches indicates that it should exist wide-spread communicating branches, and its reorganization after facial nerve reinnervation suggests that misdirected regeneration occurs among motoneurons innervating different branches.  相似文献   
7.
脾虚证计量诊断的前瞻性研究   总被引:2,自引:0,他引:2  
以本研究所修订的“脾虚证诊断标准”为金标准,通过以整群抽样取得的549例各科各系统病人(包括脾虚229例,非脾虚320例)的四诊资料对笔者以往建立的“脾虚证诊断计分表”的诊断效果做了前瞻性的研究。该计分表诊断脾虚证的几项主要评价指标的结果为:患病率41.7%,准确度91.3%,敏感度93.0%,特异度90.0%,阳性预测值86.9%,阴性预测值94.7%,阳性拟然比9.30,阴性拟然比0.08,诊断效果满意。  相似文献   
8.
持续压力超负荷对兔左心室细胞凋亡的影响   总被引:3,自引:1,他引:2  
OBJECTIVE: To study the effect of chronic pressure overload on the apoptosis of the left ventricle myocytes in rabbits. METHODS: Rabbit models of chronic pressure overload-induced heart failure were prepared in which dynamic changes of apoptotic myocytes in the left ventricle were observed by way of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. RESULTS: Only a few apoptotic cells was observed in the sham-operated group, while in the experimental group, the apoptotic left ventricle myocytes significantly increased after operation, presenting a peak level between day 3 and day 7. Seven days after the operation, the apoptotic myocytes began to decrease and till day 14, the apoptotic cell number had been smaller than that measured on day 1. When signs of heart failure set in, the apoptotic myocytes were again increased (P<0.001). CONCLUSION: During chronic pressure overload, myocyte apoptosis in the left ventricle is elevated at the early stages and undulates subsequently, with the peak occurring before hypertrophy is obvious.  相似文献   
9.
10.
以头孢呋辛钠为原料,从制备(R,S)-乙酸1-溴乙酯开始。经酯化反应的溶剂沉淀过程无须分离直接制得高纯度非晶型的头孢呋辛酯。本制备方法简便,适于工为化生产。  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