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   3011篇
  免费   221篇
  国内免费   1篇
耳鼻咽喉   19篇
儿科学   217篇
妇产科学   36篇
基础医学   402篇
口腔科学   102篇
临床医学   250篇
内科学   608篇
皮肤病学   206篇
神经病学   232篇
特种医学   181篇
外科学   288篇
综合类   18篇
一般理论   1篇
预防医学   309篇
眼科学   26篇
药学   172篇
中国医学   3篇
肿瘤学   163篇
  2023年   12篇
  2022年   20篇
  2021年   30篇
  2020年   24篇
  2019年   37篇
  2018年   65篇
  2017年   68篇
  2016年   52篇
  2015年   66篇
  2014年   89篇
  2013年   106篇
  2012年   136篇
  2011年   127篇
  2010年   109篇
  2009年   92篇
  2008年   143篇
  2007年   134篇
  2006年   142篇
  2005年   127篇
  2004年   134篇
  2003年   94篇
  2002年   103篇
  2001年   91篇
  2000年   79篇
  1999年   68篇
  1998年   53篇
  1997年   58篇
  1996年   57篇
  1995年   51篇
  1994年   47篇
  1993年   64篇
  1992年   67篇
  1991年   76篇
  1990年   74篇
  1989年   75篇
  1988年   71篇
  1987年   56篇
  1986年   49篇
  1985年   51篇
  1984年   30篇
  1983年   24篇
  1982年   21篇
  1981年   26篇
  1980年   21篇
  1979年   11篇
  1978年   11篇
  1977年   13篇
  1976年   16篇
  1975年   16篇
  1974年   9篇
排序方式: 共有3233条查询结果,搜索用时 15 毫秒
1.
Cidofovir is an acyclic nucleoside phosphonate with broad-spectrum activity against DNA viruses, including human papilloma virus (HPV). However, data on the efficacy of cidofovir in an immunosuppressive setting remain contradictory. We report for the first time on the promotion of the healing of recalcitrant warts in a patient with myelodysplastic syndrome with intravenous cidofovir treatment.  相似文献   
2.
In order to study the involvement of NMDA-receptor activation in brain development, rat pups were chronically treated with the non-competitive NMDA antagonist MK-801 during the neonatal period. We recorded the cortical EEG at various vigilance states throughout the treatment period. Spectral analysis of the EEG showed reduced power in the delta (delta) frequency range (1.5-4 Hz) during quiet sleep and less power in the theta (theta) range (4-7 Hz) during REM-sleep in MK-801 animals than in controls. No significant differences were found for the total time spent in each of the different vigilance states. We conclude that chronic MK-801 treatment probably causes a developmental retardation in state-related brain activities.  相似文献   
3.
Recently we have reported that injections of d-amphetamine into the nucleus accumbens enhanced the number of switches to cue-directed behaviours without an effect on the number of switches to non-cue-directed behaviours in a swimming test. In the present study we investigated to what extent this effect is mediated via the dopaminergic system in the nucleus accumbens. For that purpose drugs selective for D1- and D2-receptors were studied in this swimming test. It was found that the selective D2-agonist LY 171 555 (50 ng/0.5 microliters) enhanced the number of different cue-directed behaviours. The selective D2-antagonist raclopride (50 ng/0.5 microliters) decreased it. Furthermore an ineffective dose of raclopride attenuated the effect of LY 171 555. Both the selective D1-antagonist SCH 23390 (400 ng/0.5 microliters) and the selective D1-agonist SKF 38393 (50-400 ng/0.5 microliters) decreased the number of different cue-directed behaviours. The effect induced by SCH 23390 could not be blocked by SKF 38393. Similarly the effect induced by SKF could not be attenuated by SCH 23390. These data point to a role for dopamine D2-receptors in the ability to switch to cue-directed behaviours. The present findings do not yet allow the conclusion that D1-receptors are involved.  相似文献   
4.
BACKGROUND: Pre-clinical and clinical studies suggest that transplantation of bone marrow-derived stem cells can improve global cardiac function. However, no quantitative assessment of regional systolic contraction and correlation with phenotype has been made. Therefore, we used our model of cryoinfarcted rabbit myocardium for intracardiac transplantation of a mixed population of bone marrow-derived cells and assessed both regional function and myogenic conversion of the cells. METHODS: Nineteen New Zealand white rabbits underwent cryoinjury of the left ventricle. Autologous bone marrow (BM) cells were expanded in vitro. After 2 weeks, either 1 x 10(8) mixed BM-derived progenitor cells (BM group, n = 11) or vehicle (control group, n = 8) were injected into the cryoinjured region. Regional systolic function was measured using micromanometry and sonomicrometry before and 4 weeks after cell injection; cell phenotype was evaluated histologically. RESULTS: All animals in the BM group significantly improved both systolic shortening (0.11 +/- 0.7 vs -0.05 +/- 0.05 mm in the control group, p < 0.05) and regional stroke work when compared with control (9.6 +/- 2.4 vs -1.2 +/- 1.2 mm . mm Hg, p < 0.003). In addition, the BM group had improved global diastolic function, as measured by minimum dP/dt and end-diastolic pressure. On histologic assessment, BM cells differentiated toward a myogenic phenotype. CONCLUSIONS: Transplanting a mixed population of marrow-derived cells that can adopt a myogenic phenotype improves regional contractility and diastolic relaxation after myocardial infarction.  相似文献   
5.
Roth  J; Burwinkel  F; van den Bos  C; Goebeler  M; Vollmer  E; Sorg  C 《Blood》1993,82(6):1875-1883
MRP8 and MRP14 are two Ca(2+)-binding proteins of the S-100 family expressed by myelomonocytic cells. Both proteins assemble to noncovalently associated complexes in a Ca(2+)-dependent manner. Members of the S-100 family are known to play a role in cytoskeletal- membrane interactions; therefore, we investigated the subcellular distribution of MRP8/MRP14 and their complexes in human monocytes. Using differential centrifugation and subsequent Western blot or enzyme- linked immunosorbent assay analysis, we found that MRP8/MRP14 were almost completely translocated from the cytoplasma to membrane and cytoskeletal structures in a Ca(2+)-dependent manner. Using a cross- linking technique, complexed forms of MRP8/MRP14 were found to be associated with the plasma membrane. Analysis of MRP-transfected L132 cells showed that the MRP8 as well as the MRP14 component of the MRP8/MRP14 complex may independently bind to membrane and cytoskeletal structures. Furthermore, immunogold electron microscopy showed a colocalization of MRP8/MRP14 and the intermediate filament type III protein vimentin in A23187-treated monocytes. Our data indicate that, in analogy to other S-100-like proteins, MRP8 and MRP14 play a role in Ca(2+)-dependent cytoskeletal-membrane interactions. Restriction of MRP8/MRP14 expression to distinct stages of myelomonocytic differentiation suggests that these proteins are involved in highly specific pathways of intracellular signaling in phagocytes.  相似文献   
6.
7.
Sir, With great interest we read the editorial review of Jean etal. [1] on the relationship between hyperphosphataemia and mortalityin end-stage renal disease patients. The authors summarize resultsfrom the large USRDS and DOPPS studies in which associationsof hyperphosphataemia and increased mortality risks were  相似文献   
8.
9.
PURPOSE: Surgical closure of oroantral communications (OACs) has several disadvantages. An animal study was performed to test whether OACs can be closed nonsurgically with a biodegradable polyurethane (PU) foam. MATERIALS AND METHODS: In 6 rabbits, an OAC was created on both sides of the maxilla. Three rabbits were used to evaluate the animal model by applying a surgical treatment on 1 side and by leaving the other defects untreated. In the 3 other rabbits, OACs were closed with PU foam. Wound healing was evaluated clinically and histologically. RESULTS: The surgically treated defects healed without complications. The untreated defects showed complicated and delayed healing. Healing of the foam-treated OACs was dependent on the type of foam that was used. CONCLUSIONS: The rabbit is a suitable animal model for OAC investigations. It is possible to close an OAC with a biodegradable PU foam. Further research is needed to show the most suitable composition of the PU for this purpose.  相似文献   
10.
Intraoperative epicardial two-dimensional echocardiography was used in 195 patients undergoing surgery for congenital heart disease to evaluate its potential to identify new diagnostic information immediately before and after surgical correction. In 168 patients the preoperative diagnosis was confirmed by intraoperative echocardiography. In four patients, unsuspected findings were revealed, which resulted in modification of the surgical approach. In 18 patients additional morphologic information was obtained which contributed to alteration or refinement of surgical management. The adequacy of cardiac repair was assessed before closure of the chest in all patients. In six patients this information led to immediate reoperation and in four other patients to inotropic drug therapy. During congenital heart surgery, epicardial two-dimensional echocardiography may yield important information for surgical management. The technique is an essential adjunct when preoperative diagnostic studies are not conclusive or when the initial response to repair is unsatisfactory.  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