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   8650篇
  免费   454篇
  国内免费   24篇
耳鼻咽喉   75篇
儿科学   171篇
妇产科学   98篇
基础医学   983篇
口腔科学   234篇
临床医学   584篇
内科学   2294篇
皮肤病学   154篇
神经病学   507篇
特种医学   256篇
外科学   1559篇
综合类   33篇
预防医学   202篇
眼科学   199篇
药学   692篇
中国医学   33篇
肿瘤学   1054篇
  2023年   32篇
  2021年   140篇
  2020年   77篇
  2019年   111篇
  2018年   156篇
  2017年   103篇
  2016年   164篇
  2015年   160篇
  2014年   200篇
  2013年   274篇
  2012年   420篇
  2011年   390篇
  2010年   228篇
  2009年   204篇
  2008年   386篇
  2007年   412篇
  2006年   403篇
  2005年   421篇
  2004年   410篇
  2003年   401篇
  2002年   404篇
  2001年   420篇
  2000年   399篇
  1999年   347篇
  1998年   98篇
  1997年   90篇
  1996年   75篇
  1995年   77篇
  1994年   67篇
  1993年   63篇
  1992年   203篇
  1991年   179篇
  1990年   167篇
  1989年   169篇
  1988年   139篇
  1987年   149篇
  1986年   120篇
  1985年   132篇
  1984年   87篇
  1983年   74篇
  1982年   31篇
  1979年   60篇
  1978年   34篇
  1977年   31篇
  1975年   33篇
  1974年   34篇
  1973年   33篇
  1972年   39篇
  1971年   45篇
  1969年   37篇
排序方式: 共有9128条查询结果,搜索用时 15 毫秒
1.
2.
3.
Background: Ketamine potentiates intravenous or epidural morphine analgesia. The authors hypothesized that very-low-dose ketamine infusion reduces acute and long-term postthoracotomy pain.

Methods: Forty-nine patients scheduled to undergo open thoracotomy were randomly assigned to receive one of two anesthesia regimens: continuous epidural infusion of ropivacaine and morphine, along with intravenous infusion of ketamine (0.05 mg [middle dot] kg-1 [middle dot] h-1 [approximately 3 mg/h], ketamine group, n = 24) or placebo (saline, control group, n = 25). Epidural analgesia was continued for 2 days after surgery, and infusion of ketamine or placebo was continued for 3 days. Pain was assessed at 6, 12, 24, and 48 h after surgery. Patients were asked about their pain, abnormal sensation on the wound, and inconvenience in daily life at 7 days and 1, 3, and 6 months after surgery.

Results: The visual analog scale scores for pain at rest and on coughing 24 and 48 h after thoracotomy were lower in the ketamine group than in the control group (pain at rest, 9 +/- 11 vs. 25 +/- 20 and 9 +/- 11 vs. 18 +/- 13; pain on coughing, 26 +/- 16 vs. 50 +/- 17 and 30 +/- 18 vs. 43 +/- 18, mean +/- SD; P = 0.002 and P = 0.01, P < 0.0001 and P = 0.02, respectively). The numerical rating scale scores for baseline pain 1 and 3 months after thoracotomy were significantly lower in the ketamine group (0.5 [0-4] vs. 2 [0-5] and 0 [0-5] vs. 1.5 [0-6], median [range], respectively; P = 0.02). Three months after surgery, a higher number of control patients were taking pain medication (2 vs. 9; P = 0.03).  相似文献   

4.
We surgically treated a patient with biliary stricture and portal vein occlusion, after operation for gastric cancer with lymphadenectomy along the hepatoduodenal ligament, that had led to choledochal stone formation and a dilatated parabiliary venous system. A 57-year-old man without hepatic dysfunction exhibited hepatic duct dilatation with choledochal stone on ultrasonography and percutaneous transhepatic cholangiography, respectively. Pharmacoportography revealed occlusion of the portal vein and dilatation of the parabiliary venous system. Of various preoperative imaging studies used, enhanced computed tomography was most useful for delineating the surgical anatomy of the hepatoduodenal ligament. Complete preservation of the dilatated vessels, which functioned as the main portal collateral pathway, resulted in a successful choledocho-jejunostomy, with an uneventful postoperative course.  相似文献   
5.
Micro-shear bond strength of dual-cured resin cement to glass ceramics.   总被引:4,自引:0,他引:4  
OBJECTIVES: The aim of this study was to investigate the effects of sandblasting, etching, and a silane coupling agent on the ability of dual-cured resin cement to bond to glass ceramics designed for in indirect adhesive restoration. METHODS: A cast glass ceramic (Olympus Castable Ceramics) with a crystalline phase consisting of mica and beta-spondumene was selected as the substrate material. The glass surfaces, which were sandblasted, polished, or etched with phosphoric acid or hydrofluoric acid (HF), were bonded with a dual-cured resin cement (Panavia Fluoro Cement) using a dentin adhesive system (Clearfil SE Bond), both with and without a silane coupling agent. A micro-shear bond test was carried out to measure the bond strength of the resin cement to the glass surface. Each glass surface was bonded and tested using the shear test. In addition, surfaces with the bonding removed after the shear bond test, the adhesive interface between the glass and cement, and an etched glass surface without any bonding, were studied morphologically using scanning electron microscopy or field emission scanning electron microscopy. RESULTS: Usage of a silane coupling agent effectively raised the bond-strength values of resin cement (Fisher's PLSD, P<0.01). The effectiveness of using phosphoric acid etching to improve bonding was not clear (Fisher's PLSD, P>0.01). HF-etching for 30s seemed to over-etch the glass surface, resulting in adverse effects on bonding (Fisher's PLSD, P<0.01). SIGNIFICANCE: The micro-shear bond strength between Olympus Castable Ceramics and resin cement can be increased by the silane coupling agent used along with an acidic primer.  相似文献   
6.
7.
8.
Consensus is lacking concerning how to manage afferent vessels during hepatectomy, particularly as to the Pringle maneuver vs. selective hemihepatic clamping. Data for 81 hepatocellular carcinoma patients with chronic hepatitis or liver cirrhosis whose liver resection was limited to one section or less, including intraoperative data and postoperative liver function data, were analyzed retrospectively to compare two strategies. No significant differences of intraoperative data or postoperative clinical course were seen between the two groups, even in patients with chronic hepatitis or liver cirrhosis whose postoperative deterioration of liver function could be expected to be more than patients with a normal liver. The difference was evident only in serum alanine aminotransferase level on postoperative day 10 (mean ± SEM, 64.5±5.1 IU in the Pringle group vs. 51.6±4.4 IU in the selective clamping group; P<0.05). During liver resection limited to one section or less, even with underlying chronic hepatitis or cirrhosis, intermittent use of the Pringle maneuver preserved liver function to the same extent as selective clamping.  相似文献   
9.
Summary This study was undertaken to elucidate, using the Golgi method, the neuropathological change in the brain of the macular mutant mouse, whose hemizygote (Ml/y) is considered to be a model of Menkes kinky hair disease (MKHD). The hemizygote mice gradually lost weight after 10 days of age and died with emaciation and seizure around day 15. The normal littermate (+/y) was well developed. In the cerebrum, the arborization of pyramidal neurons in the layer V of the Ml/y was the same as that in the +/y on day 10. However, development of arborization in the Ml/y was delayed in comparison with that in the +/y on days 12 and 14. Purkinje cells with several somal sprouts were observed in the cerebellum in both the Ml/y and +/y on day 7. The somal sprouts in the +/y had regressed gradually by day 12, while they were still in the anterior and middle lobes of the Ml/y on day 14. Additionally, the trunks of Ml/y stem dendrites became thicker and a cactus formation was recognized on the branching portion of the dendrites on day 14. Arborization of these abnormal Purkinje cells was distinctly poor compared with that in the +/y. These results suggest that the growth of the neurons is delayed in the Ml/y and simultaneously their cytoskeletal developments are disturbed, especially in the Purkinje cells. There is a close similarity in many respects to the neuropathological change in MKHD.  相似文献   
10.
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