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   90038篇
  免费   8594篇
  国内免费   2623篇
耳鼻咽喉   667篇
儿科学   2159篇
妇产科学   723篇
基础医学   5809篇
口腔科学   554篇
临床医学   15040篇
内科学   20722篇
皮肤病学   546篇
神经病学   4816篇
特种医学   3677篇
外国民族医学   3篇
外科学   9784篇
综合类   15323篇
现状与发展   4篇
预防医学   5464篇
眼科学   980篇
药学   8167篇
  123篇
中国医学   4970篇
肿瘤学   1724篇
  2024年   372篇
  2023年   1690篇
  2022年   3151篇
  2021年   4513篇
  2020年   4542篇
  2019年   3833篇
  2018年   3461篇
  2017年   3635篇
  2016年   3530篇
  2015年   3341篇
  2014年   6113篇
  2013年   6312篇
  2012年   4842篇
  2011年   5162篇
  2010年   4196篇
  2009年   3982篇
  2008年   4046篇
  2007年   4258篇
  2006年   3818篇
  2005年   3281篇
  2004年   2663篇
  2003年   2338篇
  2002年   1979篇
  2001年   1890篇
  2000年   1482篇
  1999年   1403篇
  1998年   1174篇
  1997年   1111篇
  1996年   954篇
  1995年   979篇
  1994年   884篇
  1993年   694篇
  1992年   733篇
  1991年   625篇
  1990年   523篇
  1989年   424篇
  1988年   425篇
  1987年   399篇
  1986年   329篇
  1985年   380篇
  1984年   359篇
  1983年   237篇
  1982年   231篇
  1981年   196篇
  1980年   152篇
  1979年   141篇
  1978年   136篇
  1977年   86篇
  1976年   87篇
  1975年   55篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
Background and aims In extended liver resections, the preservation of vascular and biliary structures of the entire remnant liver is of paramount importance. The impact of venous outflow impairment and its consequences for liver regeneration and function are still a matter of debate. Materials and methods Rats (n = 75) were subjected to a 90% partial hepatectomy (PH), to a 70% liver resection with narrowing of the hepatic outflow of an additional 20% parenchyma (70%+ PH) or to an anatomic 70% PH. Postoperatively hepatocyte proliferation (Ki-67), liver function and survival were assessed. Gene expression analysis for markers of regeneration was determined by in-house complementary (DNA) arrays and quantitative real-time polymerase chain reaction (RT-PCR). Results Ninety percent PH led to a greater regenerative response as shown Ki-67 compared to animals with a 70%+PH (p < 0.05). However, liver function was equally impaired in both groups. Rats with 70% PH showed a greater proliferation index with less hepatic injury and better liver function. While mortality was 0% in the group of 70% PH, rats with 90% PH and 70+PH had a reduced survival of 75% (p < 0.05) Conclusion Venous outflow obstruction leads to an impairment of liver regeneration and liver function. In cases with critically small liver remnants, restoration of an adequate venous outflow may be mandatory.  相似文献   
974.
Objective Ileoanal pouch formation (IPAA) can be technically challenging in obese patients, and there is little data evaluating results after the procedure in these patients. We compare outcomes for patients with a body mass index (BMI) ≥30 undergoing IPAA when compared with those for patients with BMI <30. Methods Retrospective analysis of prospectively accrued data for patients with BMI ≥30 undergoing IPAA. Patient and disease-related characteristics, complications, long-term function, and quality of life (QOL) using the Cleveland Global Quality of Life scale (CGQL) were determined for this group of patients (group B) and compared with those for patients with BMI <30 (group A). Kruskal–Wallis and Wilcoxon rank sum tests were used to compare quantitative or ordinal data and chi-square or Fisher’s exact tests for categorical variables. Long-term mortality and complication rates were estimated using the Kaplan–Meier method with group comparisons performed using log rank tests. Results There were 345 patients (median BMI 32.7) in group B and 1,671 patients in group A. When the cumulative risk of complications over 15 years was compared, group B patients had a significantly higher chance of getting a complication (94.9% vs 88%, p = 0.006). The rates of pelvic sepsis (6.7% vs 5.3%, p = 0.3), pouchitis (58.1 vs 54.4%, p = 0.9), pouch failure (6% vs 4.5%, p = 0.9), and hemorrhage (5.6% vs 4.8%, p = 0.7) were similar for group B and group A. Group B patients, however, had a significantly higher risk of the development of wound infection (18.8% vs 8.1%, p < 0.001) and anastomotic separation (10.4% vs 5.4%, p < 0.001), whereas group A patients had a higher rate of development of obstruction over time (26.7% vs 22.3%, p = 0.02). Long-term outcome including QOL and function after 15 years was comparable between groups. Conclusions Although technically demanding, IPAA can be undertaken in obese patients with acceptable morbidity. Good long-term functional results and QOL that is comparable to nonobese patients may be anticipated.  相似文献   
975.
Evaluation of renal function should be performed as part of the follow-up during and after chemotherapy in pediatric cancer patients. The aim of this study was to compare an isotope clearance method [isotope glomerular filtration rate (iGFR)] with alternative methods to determine GFR in such patients. Isotope GFR [99mTc-labeled diethylene triaminopentoacetic acid (DTPA) or 51Cr-labeled ethylenediaminetetra-acetate (EDTA)] was measured in 36 children (112 studies) and compared with simultaneously measured creatinine clearance (CrCl), serum creatinine (SCr), and cystatin C (CysC) concentrations, as well as the results of Schwartz, Counahan–Barratt, and Cockroft–Gault formulae, using general linear mixed models. Our results showed a significant association between iGFR and CysC concentrations (p < 0.001). No linear relationship was observed between CrCl and iGFR (p = 0.7). As expected, the results of height-based formulae (Counahan–Barratt and Schwartz) had significantly (p = 0.004) better correlation to iGFR than the results of a formula based on weight (Cockroft–Gault) (p = 0.19). Despite significant linear correlation, intraclass correlation coefficients showed poor agreement. Tests of similarity between iGFR estimates showed differences between average values of GFR. Therefore, determination of iGFR remains the method of choice in estimation of GFR in cancer patients. In our study population, assay of serum CysC was the most reliable alternative method to measure glomerular function.  相似文献   
976.
The incidence of acute rejection is significantly higher in hepatitis C virus (HCV) liver-transplant patients than in patients who have received a graft for other liver diseases, i.e., mainly alcoholic cirrhosis. The aim of this study was to assess T-cell function, i.e., intralymphocyte cytokine expression (IL-2 and TNF-alpha), T-cell activation [i.e., transferrin receptor (CD71) and interleukin (IL)-2 alpha-chain (CD25) expression], and T-cell proliferation using a flow-cytometry whole-blood assay in patients waiting for a liver transplantation (n=49). Our data suggest that, in mitogen-stimulated T-cells, (i) intra-lymphocyte cytokine expression is significantly higher in patients with liver disease than in healthy volunteers (n=25); (ii) the expression of T-cell activation markers is decreased in patients with liver cirrhosis compared to healthy volunteers, and (iii) the expression of T-cell activation markers and T-cell proliferation are increased in patients with HCV infection (n=15) compared to those without HCV infection (n=34), particularly compared to patients with alcoholic liver disease (n=19). Circulating CD19-positive cells count was also significantly higher in HCV-positive patients. In conclusion, in vitro, mitogen-stimulated T-cell seem to induce a higher immune response in the blood from patients waiting for a liver transplant for HCV-related liver disease than those without HCV infection, and particularly those with alcoholic liver disease.  相似文献   
977.
978.
自体血回输对病人血浆肝素含量的影响   总被引:12,自引:0,他引:12  
目的 观察自体血回输对病人血浆中肝素含量的影响 ,探讨肝素在血液回收时的应用。方法 自体血液回输组 (n =32 )与异体输血组 (n =30 )骨科、脑科择期手术病人 ,男女各半 ,年龄 18~ 48岁 ,术前肝、肾、凝血功能均正常 ,无其他血液系统疾病。自体回输血量及异体输血量均超过 10 0 0ml。采用凝固法测定血浆中肝素含量 ;ACT Ⅱ型测定仪测定血中活化凝血时间 (ACT)。结果肝素含量 :自体血液回输组 ,术前、输血前、输血后 2小时肝素含量分别为 (0 6 5± 0 2 7)、(0 6 8±0 2 0 )和 (0 72± 0 19)U/ml;异体输血组分别为 (0 6 3± 0 2 4)、(0 6 7± 0 2 8)和 (0 6 9± 0 2 0 )U/ml。两组间均无显著差异 (P >0 0 5 )。ACT :自体血回输组三个不同时间分别为 (86 10± 2 0 5 4)、(133 5 0± 2 9 6 5 )和 (95 0 5± 2 9 71)秒 ;异体输血组分别为 (88 42± 18 37)、(131 70± 2 7 36 )和(92 86± 14 35 )秒。两组ACT值输血前均明显长于术前 (P <0 0 5 ) ,术前与输血后 2小时无显著差异 (P >0 0 5 )。结论 自体血液回输组与异体输血组术前、输血前、输血后 2小时肝素含量无显著差异。自体血回输中使用肝素抗凝适量 ,安全可行  相似文献   
979.
目的 :探讨应用安雄进行雄激素替代对去势大鼠勃起功能的影响。方法 :取40只成年雄性 SD大鼠 ,分为去势、高、低剂量安雄及假手术 4组。治疗 4周后采用阿朴吗啡 ( APO)皮下注射与电刺激海绵体神经诱导大鼠勃起 ,对其勃起功能进行评价。结果 :高、低剂量安雄组与假手术组大鼠 APO诱导的勃起成功率、勃起次数与电刺激诱导的海绵体内压 ( ICP)均较去势组大鼠为高或多 ,统计学处理差异有显著性 ( P<0 .0 1 )。结论 :通过 APO皮下注射和电刺激海绵体神经证实 ,去势导致大鼠勃起功能明显下降 ;采用安雄进行雄激素替代可恢复其勃起功能 ;去势既影响了药物诱发的勃起反应 ,也损伤了外周电刺激诱导的勃起反应  相似文献   
980.
Lo CY 《ANZ journal of surgery》2002,72(12):902-907
Permanent hypoparathyroidism is a debilitating morbidity following thyroidectomy, with a reported incidence of up to 43%. Apart from meticulous dissection to preserve parathyroid glands and their blood supply, parathyroid autotransplantation (PA) has been increasingly employed to preserve parathyroid function. The adoption of PA during thyroidectomy has been reported to be associated with a low incidence of permanent hypoparathyroidism. Biochemical function of parathyroid autografts can be demonstrated objectively by forearm reimplantation or during long-term follow up. The clearest indication for PA is for inadvertently removed or devascularized parathyroid glands during thyroid surgery. Other strategies, including routine autotransplantation of at least one parathyroid gland, can be considered, but is associated with a high incidence of transient hypocalcaemia. Apart from refinement in technique to facilitate graft success, a reliable way to assess overall parathyroid function or viability of individual parathyroid gland may assist in monitoring parathyroid function and selecting patients requiring this procedure to prevent permanent hypoparathyroidism.  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