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   13567篇
  免费   1284篇
  国内免费   60篇
耳鼻咽喉   178篇
儿科学   386篇
妇产科学   337篇
基础医学   1862篇
口腔科学   763篇
临床医学   1179篇
内科学   3181篇
皮肤病学   316篇
神经病学   1142篇
特种医学   575篇
外科学   1897篇
综合类   102篇
一般理论   5篇
预防医学   1087篇
眼科学   242篇
药学   750篇
中国医学   42篇
肿瘤学   867篇
  2023年   65篇
  2022年   171篇
  2021年   331篇
  2020年   228篇
  2019年   370篇
  2018年   466篇
  2017年   339篇
  2016年   368篇
  2015年   407篇
  2014年   506篇
  2013年   606篇
  2012年   856篇
  2011年   827篇
  2010年   562篇
  2009年   462篇
  2008年   674篇
  2007年   763篇
  2006年   648篇
  2005年   621篇
  2004年   526篇
  2003年   483篇
  2002年   422篇
  2001年   350篇
  2000年   319篇
  1999年   347篇
  1998年   141篇
  1997年   139篇
  1996年   125篇
  1995年   100篇
  1994年   109篇
  1993年   96篇
  1992年   233篇
  1991年   212篇
  1990年   184篇
  1989年   204篇
  1988年   182篇
  1987年   156篇
  1986年   163篇
  1985年   162篇
  1984年   114篇
  1983年   95篇
  1982年   56篇
  1981年   62篇
  1979年   73篇
  1978年   62篇
  1976年   51篇
  1975年   53篇
  1974年   40篇
  1973年   54篇
  1972年   46篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
Well-fitted dentures prevent hyperplasic lesions, provide chewing efficiency and promote patient's comfort. Several factors may affect final adaptation of dentures, as the type of the acrylic resin, the flask cooling procedure and the water uptake. This investigation evaluated the effect of water storage and two different cooling procedures [bench cooling (BC) for 2 h; running water (RW) at 20 degrees C for 45 min] on the final adaptation of denture bases. A heat-cured acrylic resin (CL, Clássico, Clássico Artigos Odontológicos) and two microwave-cured acrylic resins [Acron MC, (AC) GC Dent. Ind. Corp.; Onda Cryl (OC), Clássico Artigos Odontológicos] were used to make the bases. Adaptation was assessed by measuring the weight of an intervening layer of silicone impression material between the base and the master die. Data was submitted to ANOVA and Tukey's test (0.05). The following means were found: (BC) CL=0.72 +/- 0.03 a; AC=0.70 +/- 0.03 b; OC=0.76 +/- 0.04 c//(RW) CL= 1.00 +/- 0.11 a; AC=1.00 +/- 0.12 a; OC=0.95 +/- 0.10 a. Different labels join groups that are not statistically different (P > 0.05). Comparisons are made among groups submitted to the same cooling procedure (BC or RW). The conclusions are: interaction of type of material and cooling procedure had a statistically significant effect on the final adaptation of the denture bases (P < 0.05); water storage was not detected as a source of variance (P > 0.05) on the final adaptation.  相似文献   
993.
994.
995.
996.
Searching for a novel immunosuppressive agent to effectively prevent acute vascular rejection (AVR) is essential for success in clinical xenotransplantation. We previously reported that Lewis rat hearts transplanted into BALB/c mice developed typical AVR in 6 days. The present study was undertaken to determine the efficacy of LF 15-0195, a new immunosuppressive analog of 15-deoxyspergualin in the prevention of AVR in a rat-to-mouse cardiac xenograft model. We transplanted 2-week old Lewis rat hearts into BALB/c mice. Four groups were included in this study: untreated recipients and cyclosporin A (CsA) treated recipients were controls; LF 15-0195 treated recipients or LF 15-0195 combined with CsA treated recipients were experimental groups. Mouse recipients received either LF 15-0195 2 mg/kg subcutaneously from day-1 to post-operative day 14, or CsA 15 mg/kg subcutaneously daily, from day 0 to endpoint rejection, or the two drugs in combination. We observed that high dose CsA did not inhibit AVR and the graft was rejected in 11.3 +/- 1.9 days. Graft histology and immunohistology showed typical AVR, characterized by interstitial hemorrhage, intravascular fibrin deposition, thrombosis, and massive deposition of anti-rat immunoglobulin G (IgG) and immunoglobulin M (IgM). Serum xenoreactive antibodies (xAbs) were markedly elevated in these animals as well. In contrast, we observed that treatment with LF 15-0195 alone significantly prolonged graft survival to 19.3 +/- 0.7 days. Notably, xAbs were significantly decreased and the rejection pattern of these grafts was cell-mediated rejection (CMR), instead of AVR. When CsA was combined with LF 15-0195, the graft mean survival time was further increased to 58.5 +/- 17.3 days. Antibody production and T-cell infiltration were significantly inhibited at the terminal stages of graft survival and pathology showed striking attenuation of both AVR and CMR. Sequential studies on days 6 and 14 demonstrated that LF 15-0195 either alone or combined with CsA completely inhibited antibody production. However, intragraft infiltration by Mac-1 positive cells including natural killer cells, macrophages and granulocytes in LF 15-0195 treated recipients was similar to that of untreated recipients. We conclude that LF 15-0195 effectively prevented AVR by markedly inhibiting the production of anti-donor IgG xAbs. Also, treatment with short course LF 15-0195 and continuous CsA significantly reduced T-cell infiltration. Studies to test this therapy in inhibiting AVR in a pig-to-non-human primate xenotransplantation model are underway.  相似文献   
997.
The purpose of this article was to document the efforts of two military installations in facilitating Critical Incident Stress Management teams for Federal Emergency Management Agency Rescue and Recovery Units following the attacks on the World Trade Center on September 11, 2001. McGuire Air Force Base accepted the mission to support the rotating task forces with emotional support, and Fort Dix offered temporary lodging while the teams were in-bound and out-bound to the "Ground Zero" site. A team, comprised of staff from both installations due to the configuration of professional and support staffs, does the Critical Incident Stress Management work. Both installations are within commuting distance of New York City and could provide adequate safety, security, and logistics to the teams. The classic crisis management models were not called into play, as that service was not asked for; however, it was clear to the McGuire Air Force Base/Fort Dix Critical Incident Stress Management team members that the rescue and recovery teams needed their physical presence. Many rescue organizations have their own "debriefing teams," yet it is believed that "outside teams" may be helpful as interim measures to demonstrate the universality of the process of coping with traumatic stress and grief management. It is hoped that this article honors the workers who came together to help in a very difficult time for our country. This article documents the interim measures that were taken for a group of people moving through crisis.  相似文献   
998.
Recipient portal vein thrombosis in liver transplantation is a contingency that increases surgical difficulty as well as patient morbidity and mortality. The aim of this paper is to demonstrate a surgical technique for reconstruction of portal blood flow in emergency situations of portal vein thrombosis with inadequate blood flow and a poor vascular bed for re-vascularization.  相似文献   
999.
In this article, a flow system developed for the amperometric determination of a great variety of pharmaceuticals that are known to lead the rapid poisoning of the working electrode surface is described. The referred system was made up of two parallel flow channels that shared the voltammetric detector of tubular configuration, whose movement in the manifold followed the concept of multi-site location of detector. In this way, after each measurement, the conditioning of the working electrode was possible through the passage by its surface of a regeneration solution without implying the alteration of the carrier that flowed in the analytical channel of the manifold. The methodology proposed was evaluated through the determination of two drugs belonging to two distinct therapeutic groups: an antihypertensive (diltiazem) and a non-steroid anti-inflammatory (nimesulide). The results obtained after evaluation of various pharmaceutical formulations on the Portuguese market were in the case of diltiazem compared with those supplied by the reference US Pharmacopoeia XXIV method, with no statistically significant differences having been observed for a confidence interval of 95%. In the case of nimesulide, since no official reference method exists, a series of recovery experiments were proceeded with and a mean value of 101.1% with a R.S.D. of 0.7% was obtained.  相似文献   
1000.
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