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   1349篇
  免费   148篇
  国内免费   65篇
耳鼻咽喉   2篇
儿科学   85篇
妇产科学   1篇
基础医学   87篇
口腔科学   43篇
临床医学   77篇
内科学   176篇
皮肤病学   59篇
神经病学   32篇
特种医学   12篇
外科学   341篇
综合类   149篇
现状与发展   1篇
预防医学   7篇
眼科学   72篇
药学   336篇
中国医学   56篇
肿瘤学   26篇
  2024年   2篇
  2023年   9篇
  2022年   17篇
  2021年   21篇
  2020年   26篇
  2019年   31篇
  2018年   43篇
  2017年   42篇
  2016年   39篇
  2015年   51篇
  2014年   56篇
  2013年   131篇
  2012年   62篇
  2011年   54篇
  2010年   66篇
  2009年   72篇
  2008年   78篇
  2007年   78篇
  2006年   86篇
  2005年   82篇
  2004年   53篇
  2003年   58篇
  2002年   59篇
  2001年   48篇
  2000年   37篇
  1999年   44篇
  1998年   30篇
  1997年   33篇
  1996年   30篇
  1995年   29篇
  1994年   12篇
  1993年   13篇
  1992年   11篇
  1991年   14篇
  1990年   12篇
  1989年   11篇
  1988年   11篇
  1987年   2篇
  1986年   3篇
  1985年   6篇
排序方式: 共有1562条查询结果,搜索用时 31 毫秒
21.
移植肾彩色多普勒血流超声与肾穿刺活检的对照研究   总被引:2,自引:0,他引:2  
晏沐阳  王炼 《医学争鸣》1998,19(1):57-60
将彩色多普勒血流超声与移植肾活检结果相对照。评价无创性CDFI对移植肾排异反应的诊断价值。结果:不同病理状态下移植肾的阻力指数有所不同。急性排异和慢性排异反应组的RI值明显高于正常组。两次肾活检提示由急性排异转为慢性排异反应的同一患者,CDFI的动态观察显示,RI值明显增高。  相似文献   
22.
The results of cadaveric retransplantation in 55 recipients immunosuppressed with cyclosporine and prednisone were compared to 156 recipients of primary renal allografts. By 3 yr posttransplant, there is no significant difference in patient survival, but the yearly graft survival for primary (79%, 72%, 72%) as compared to retransplant (69%, 58%, 58%) recipients was significantly (p less than 0.05) better. There was no significant difference in rejection episodes or mean +/- SD serum creatinine (mg/dl) at 2 yr between primary (32%, 2.14 +/- 1.1) and retransplant (33%, 2.08 +/- 1.4) patients, respectively. Donor source, third kidneys, human leukocyte antigen AB and Dr matching, percent reactive antibody levels, and cause of first graft loss do not have significant impact on cyclosporine-treated retransplant outcome. However, retransplant patients who have lost a previous graft in less than 3 months continue to be at high risk for subsequent early graft loss. These results suggest that the combination of cyclosporine and prednisone is the preferred regimen for cadaveric retransplantation.  相似文献   
23.
(LEW X BN)F1 cardiac allografts are rejected within 8 days in untreated LEW recipients. At the critical time point of 5 days after transplantation, the obviously rejecting grafts are enlarged and maximally infiltrated by host cells as shown by 111In-labeled lymphocyte tracer studies. However, when such hearts were retransplanted back to naive (LEW X BN)F1 secondary hosts, they survive indefinitely, showing that even late rejection is reversible in the absence of sustained host immunological drive. Attempts were then made to abrogate this advanced immune responsiveness using Cyclosporine (CsA). CsA therapy (15 mg/kg/day for 7 days) starting from day 5 produced indefinite graft survival, similar as if initiated at the time of operation. Addition of exogenous IL-2, which drives the proliferation of Tc, could not reverse this effect. Serial changes in phenotype of lymphocyte subpopulations infiltrating both acutely rejecting and indefinitely functioning cardiac allografts in unmodified and CsA treated hosts, respectively, were then studied. Ratio of Th:Tc/s cells in acutely rejecting grafts was 1.6 by day 3; it inverted abruptly to 0.7 by day 5-6, suggesting predominance of Tc/s during the later stages of allograft rejection. Similarly, treatment with CsA produced a transient depression of Th, with recovery of original Th:Tc/s ratio during the next 2-3 weeks. Adoptive transfer experiments were then performed to investigate the functional significance of these findings.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
24.
新免疫抑制剂雷帕霉素抗移植排斥作用的实验研究   总被引:2,自引:1,他引:2  
作者研究了雷帕霉素(rapamycin;RPM)对C57BL/6J→BALB/c小鼠心肌和皮肤移植的抗移植排斥作用,结果表明 RPM比目前应用于临床器官移植的环孢菌素(Cyclosporine A;CsA)具有更好的抗移植排斥作用。此外还观察了 RPM对正在进行的移植心肌排斥反应的作用,RPM于小鼠心肌移植后第 7天开始给药与0天开始给药组相比较,移植心肌的平均存活天数无明显差异,表明RPM对心肌移植排斥反应有很好的治疗作用。小剂量的RPM与亚治疗剂量的CsA合用还有很好的协同作用。  相似文献   
25.
Despite the increasing numbers of paediatric transplants performed, little is known about the immune responses of T lymphocytes in human neonates. Here we have compared the effects of cyclosporine on the phytohaemagglutinin (PHA) response of immature (cord) and mature (adult) lymphocytes using the following parameters of activation: (i) proliferation, measured by 3H-thymidine uptake; (ii) expression of cell surface IL-2 receptor; (iii) release of IL-2 into the supernatant. Cyclosporine was added to cultures of PHA-stimulated lymphocytes at doses ranging from 5 to 5000 ng/ml. The proliferative response of cord lymphocytes was considerably more sensitive to cyclosporine at each dose, so that 50% inhibition was achieved by 6 ng/ml and 21.5 ng/ml doses of cyclosporine on cord and adult lymphocytes, respectively. Expression of the IL-2 receptor by PHA-activated T cells and their subsets was assessed by flow cytometry. Cyclosporine inhibited IL-2 receptor expression to a significantly greater degree in cord CD4 and CD8 cells (49.7% and 70.1%) than in adults (17.9% and 30.0%). Biologically active IL-2 release was measured using the IL-2-dependent cell line CTLL-2. Cyclosporine at doses 50-5000 ng/ml produced 80-99% inhibition of both cord and adult responses. However, at very low doses (5 ng/ml) cyclosporine produced 69.3% inhibition of cord lymphocytes, compared with 42.0% of adult lymphocytes. These results suggest that the T cells of neonates are considerably more sensitive to cyclosporine than are adult T cells.  相似文献   
26.
The present study examined the effect of cyclosporine (CsA) administered with steroidin vivo on the capacity of peripheral blood mononuclear cells (PBMC) from kidney transplant recipients to generate cytokines and their gene expression at the level of messenger RNA (mRNA). PBMC from CsA-prednisolone (Pred)-treated recipients displayed 66.9% inhibition (54.3±12.4 IU/ml;N=42;P<0.01) of -interferon (-IFN) production compared with normal individuals (134.6±18.6 IU/ml;N=23). Azathioprine (Az)-Pred-treated recipients displayed significantly less inhibition of -IFN generation (96.0±16.1 IU/ml;N=22;P<0.05) than CsA-treated patients. Macrophages (m) from CsA-Pred-treated recipients displayed 60.0% inhibition (5.1±0.7 U/ml;N=20;P<0.01) of interleukin-1 (IL-1) production compared with normal individuals (13.0±2.9 U/ml;N=21). These results were confirmed by the experiments using cDNA probe for -IFN or IL-1 (, ). High levels of -IFN mRNA in phytohemagglutinin (PHA)-stimulated PBMC or IL-1() mRNA in lipopolysaccharide (LPS)-stimulated m were present in normal individuals but not in CsA-treated recipients as judged by hybridization to a cloned human -IFN or IL-1() cDNA probe. These studies demonstrated that combination therapy of CsA with steroid inhibits both -IFN and IL-1 gene expression at the level of mRNA at physiological concentrations.  相似文献   
27.
环孢素A对实验大鼠脑缺血治疗作用的组织化学研究   总被引:3,自引:1,他引:2  
【目的】进一步证实免疫因素在脑缺血病理变化中的作用。【方法】将 6 0只局部脑缺血模型SD大鼠分为缺血 3d ,1周和 2周 3个缺血时间组 ,每组分为生理盐水对照和环孢素A治疗两个部分 ,进行TTC和HE组化染色实验 ,并对结果进行统计处理 (t检验 )。【结果】脑缺血 1周 ,环孢素处理组的组织病理学变化较生理盐水对照组明显减轻 ,脑梗塞体积和死亡的神经元数量在环孢素A处理组分别为 3 2 %和 15 8/ 0 0 6 2 5mm2 ,而生理盐水组则为 5 9%和 2 2 1/ 0 0 6 2 5mm2 ,两组之间有显著差异 (P <0 0 5 )。但在脑缺血 3d和 2周组 ,上述变化两组之间无统计学差异。【结论】环孢素A对实验大鼠的缺血性神经元具有一定保护作用 ,结果提示免疫因素的介入 ,加重了脑缺血性损伤。  相似文献   
28.
AIM: The characteristics of transepithelial transport and uptake of CPU-86017 {[7-(4-chlorbenzyl)-7,8,13,13α-tetrahydroberberine chloride, CTHB]}, a new antiarrhythmia agent and a new derivative of berberine, were investigated on epithelial cell line (Caco-2) to further understand the absorption mechanism of berberine and its derivatives. METHODS: Caco-2 cell was used. RESULTS: 1) The permeability coefficient from the apical (AP) to basolateral (BL) of CPU-86017 was approximately 5 times higher than that from BL-to-AP transport. The effects of a P-glycoprotein (P-gp) inhibitor-cyclosporin A, some surfactants, and lower pH on the transepithelial transport of CPU-86017 were also observed. Cyclosporine A at 7.5 mg/L had no effect on the transepithelial electrical resistance (TEER); an about 4-fold enhancement on the transepithlial transport of CPU-86017 was observed. Some surfactants (sodium citrate, sodium deoxycholate, and sodium dodecyl sulfate) at 100 μmol/L and low pH (pH=6.0) induced a reversible d  相似文献   
29.
Despite improvements in short-term graft and patient survival rates for solid organ transplants, certain subgroups of transplant recipients experience poorer clinical outcome compared to the general population. Groups including pediatrics, African-Americans, diabetics, cystic fibrosis patients, and pregnant women require special considerations when designing immunosuppressive regimens that optimize transplant outcomes. Problems specific to pediatric transplant recipients include altered pharmacokinetics of immunosuppressive drugs, such as cyclosporine (CsA) and tacrolimus (poor absorption, increased metabolism, rapid clearance), the need to restore growth post-transplantation, and a high incidence of drug-related adverse effects. African-Americans have decreased drug absorption and bioavailability, high immunologic responsiveness, and a high incidence of post-transplant diabetes mellitus. Diabetics and cystic fibrosis patients exhibit poor absorption of immunosuppressive agents, which may lead to underimmunosuppression and subsequent graft rejection. Pregnant women undergo physiologic changes that can alter the pharmacokinetics of immunosuppressives, thus requiring careful clinical management to minimize the risks of either under- or overimmunosuppression to mother and child. To achieve an optimal post-transplant outcome in these high-risk patients, the problems specific to each group must be addressed, and immunosuppressive therapy individualized accordingly. Drug formulation greatly impacts upon pharmacokinetics and the resultant level of immunosuppression. Thus, a formulation with improved absorption (e.g., CsA for microemulsion), higher bioavailability, and less pharmacokinetic variability may facilitate patient management and lead to more favorable outcomes, especially in groups demonstrating low and variable bioavailability. Other strategies aimed at improving transplant outcome include the use of higher immunosuppressive doses, different combinations of immunosuppressive agents, more frequent monitoring, and management of concurrent disease states.  相似文献   
30.
眼用环孢霉素A缓释超微粒的制备及眼内分布研究   总被引:5,自引:0,他引:5  
目的探讨壳聚糖-胆固醇双亲性聚合物包载环孢霉素A的缓释性及超微粒制备及眼内分布.方法壳聚糖-胆固醇双亲性聚合物与环孢霉素A共溶于溶剂中,对水透析形成超微载药微粒,37℃条件下测试超微粒体外释放状态.以放射性99锝标记壳聚糖超微粒,制成滴眼剂,以SPECT测试超微粒在兔眼中的滞留时间.结果壳聚糖载药超微粒可在6小时内缓释环孢霉素A,超微粒在给药后4小时在眼表具有良好的滞留性.结论以壳聚糖双亲性聚合物包载环孢霉素A对干眼症的治疗具有潜在的应用价值.  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