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   885篇
  免费   49篇
  国内免费   59篇
儿科学   45篇
妇产科学   7篇
基础医学   56篇
口腔科学   13篇
临床医学   154篇
内科学   232篇
皮肤病学   17篇
神经病学   15篇
特种医学   278篇
外科学   51篇
综合类   27篇
预防医学   26篇
眼科学   8篇
药学   33篇
中国医学   2篇
肿瘤学   29篇
  2022年   3篇
  2021年   10篇
  2020年   3篇
  2019年   3篇
  2018年   12篇
  2017年   3篇
  2016年   1篇
  2015年   13篇
  2014年   14篇
  2013年   25篇
  2012年   10篇
  2011年   13篇
  2010年   29篇
  2009年   20篇
  2008年   17篇
  2007年   49篇
  2006年   12篇
  2005年   21篇
  2004年   17篇
  2003年   15篇
  2002年   15篇
  2001年   17篇
  2000年   11篇
  1999年   13篇
  1998年   54篇
  1997年   35篇
  1996年   59篇
  1995年   45篇
  1994年   41篇
  1993年   50篇
  1992年   15篇
  1991年   12篇
  1990年   27篇
  1989年   31篇
  1988年   43篇
  1987年   37篇
  1986年   30篇
  1985年   31篇
  1984年   18篇
  1983年   12篇
  1982年   13篇
  1981年   24篇
  1980年   19篇
  1979年   7篇
  1978年   9篇
  1977年   15篇
  1976年   8篇
  1975年   9篇
  1970年   1篇
  1963年   1篇
排序方式: 共有993条查询结果,搜索用时 15 毫秒
31.
目的利用4种不同支架材料构建复合式口腔黏膜,并比较其组织结构特点。方法体外培养人口腔黏膜的成纤维细胞和角质形成细胞,在4种支架材料中加入成纤维细胞,培养7d后,在支架表面加入角质形成细胞,培养4d后,移至气-液界面继续培养7d。苏木精-伊红染色镜下观察构建的复合式口腔黏膜的组织形态学特点。结果 4种支架均可构建形成复层上皮。其中,上皮层与脱细胞真皮基质材料(de-epidermised dermis,DED)结合紧密,形成的人工黏膜有明显的上皮钉突。不同于以往报道,上皮层与Alloderm结合并不十分紧密。以胶原凝胶为基质形成的人工口腔黏膜最厚,有明显分层。以胶原海绵-胶原凝胶为基质形成的复层上皮在部分区域长入至胶原海绵的空隙中。结论以DED和胶原凝胶为支架构建的口腔黏膜更接近于天然结构,而后者脆性较大,限制了其临床应用的可能。  相似文献   
32.
肠息肉发生的细胞和分子生物学研究进展   总被引:1,自引:0,他引:1  
肠息肉是一类从黏膜表面突出到肠腔内的隆起状病变的临床诊断.在最近的研究中陆续证实,其发生和发展的原因和机制,是由于Bmprla,APC,SMAD4,PTEN,STK11等基强突变而使各种细胞信号分子通过影响BMP信号通路,PTEN信号通路及Wnt信号通路所组成的生长信号调控网络,造成β-catenin在肠干细胞中的过度积聚,使得肠干细胞功能紊乱,导致其自我更新、克隆增殖、分化和凋亡失去平衡的结果.  相似文献   
33.
34.
The present study was undertaken to assess the temporal association between the profiles of serum concentrations of oestradiol-17beta, progesterone, chorionic gonadotrophin (CG) and relaxin in pregnancies established naturally, and after embryo transfer, as well as in failed pregnancies in rhesus monkeys. In naturally mated cycles (group 1) a conception rate of 75% was obtained. In group 1, the mean day of CG detection in serum was 11.5 +/- 1.9 day post-ovulation, and for relaxin, 9.0 +/- 2.5 day post-ovulation. In group 2, embryo transfer to synchronous, non-mated surrogate recipients was performed; seven embryo transfer cycles yielded three pregnancies which were allowed to continue to term and normal infants were delivered. In embryo transfer cycles the mean day of CG detection was 14.8 +/- 1.8 day post- ovulation, and for relaxin, 11.4 +/- 2.6 day post-ovulation. A delay of about 3 days was observed in the appearance in circulation of CG (P < 0.05) and also of relaxin (P < 0.05) between natural mated and embryo transfer conception cycles. Significant differences (P < 0.05 for progesterone and P < 0.03 for oestradiol) were obtained for the areas under the curves for progesterone and oestradiol between days 12 and 16 in conception cycles compared with failed pregnancies. These data provide the first observation of the normal hormonal signals associated with maternal recognition of transferred embryos during the peri- implantation period, and suggest that the use of such an experimental primate embryo transfer model may help to elucidate components of maternal and embryonic signal-response mechanisms during embryo implantation.   相似文献   
35.
36.
37.
The depth of myometrial invasion by endometrial carcinoma was evaluated using real-time sonography (US) in 20 patients with histologically proved adenocarcinoma of the endometrium. In 14 of 20 (70%) cases, US-based estimation of the depth of myometrial invasion was within 10% of the actual measurement in the gross specimen. The US-based estimation of tumor invasion was low in seven patients, high in four patients, and agreed with pathologic findings (+/- 5%) in nine patients. In four patients with polypoid intraluminal extension of tumor, a deeply invasive tumor was suspected on US but was not found on pathologic examination. In 12 superficially invasive tumors, the continuity of the demarcating subendometrial halo was intact in nine and incomplete in three. In six patients with deeply invasive tumors, this zone was partially disrupted in four, totally disrupted in one, and intact in one. Errors of estimation of the depth of myometrial invasion on US most frequently occurred when a tumor had a significant intraluminal polypoid extension. Demonstration of a subendometrial halo usually indicated superficial invasion, whereas the absence of a halo was frequently associated with deep invasion.  相似文献   
38.
Insertion of a screw biopsy stylet into a thin-walled biopsy needle greatly enhances detection of the needle during ultrasound-guided percutaneous biopsy. This technique is helpful when precise needle-tip localization is needed for biopsies of small lesions.  相似文献   
39.
Occlusion of varicoceles wih detachable balloons   总被引:1,自引:0,他引:1  
  相似文献   
40.
Malacoplakia is a distinct pathologic lesion usually involving the urinary bladder. The lesions consist of smooth, yellowish brown plaques in the mucosa varying from 0.1 to 0.3 cm in diameter. The lesion was first described by Michaelis and Gutmann in 1902, and was subsequently named malacoplakia (“soft plaque”) by von Hansemann in 1903. This report describes a case of renal parenchymal malacoplakia presenting on excretory urography as a cystic renal mass associated with malacoplakia involving the ureter and bladder. The usual urographic differential diagnoses of a cystic renal mass include cystic renal cell carcinoma, mutilocular cyst, benign cystic nephroma, hemorrhagic cyst, hematoma, and renal abscess. In patients, especially females, with a renal mass associated with a history of repeated urinary tract infections, altered immune syndromes, abnormal cystoscopic findings, or filling defects in the collecting system or urter, renal parenchymal malacoplakia should be included in the differential diagnosis.  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