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   816篇
  免费   56篇
  国内免费   2篇
耳鼻咽喉   2篇
儿科学   14篇
妇产科学   10篇
基础医学   97篇
口腔科学   13篇
临床医学   43篇
内科学   269篇
皮肤病学   4篇
神经病学   46篇
特种医学   36篇
外科学   157篇
综合类   4篇
预防医学   34篇
眼科学   8篇
药学   27篇
肿瘤学   110篇
  2022年   7篇
  2021年   8篇
  2020年   9篇
  2019年   7篇
  2018年   14篇
  2017年   13篇
  2016年   12篇
  2015年   14篇
  2014年   15篇
  2013年   25篇
  2012年   25篇
  2011年   43篇
  2010年   15篇
  2009年   25篇
  2008年   43篇
  2007年   59篇
  2006年   66篇
  2005年   74篇
  2004年   67篇
  2003年   48篇
  2002年   42篇
  2001年   29篇
  2000年   25篇
  1999年   26篇
  1998年   7篇
  1997年   14篇
  1996年   10篇
  1995年   8篇
  1993年   5篇
  1992年   7篇
  1991年   10篇
  1990年   4篇
  1989年   8篇
  1988年   5篇
  1987年   4篇
  1985年   4篇
  1983年   3篇
  1982年   5篇
  1981年   4篇
  1980年   2篇
  1979年   9篇
  1978年   4篇
  1977年   6篇
  1976年   3篇
  1974年   5篇
  1973年   12篇
  1972年   5篇
  1971年   5篇
  1970年   3篇
  1966年   2篇
排序方式: 共有874条查询结果,搜索用时 15 毫秒
11.
12.
We have validated ECG-gated emission tomography using technetium-99m methoxyisobutylisonitrile for the assessment of regional ventricular function by comparing it with cine magnetic resonance imaging (MRI). Gated tomography was performed at rest in 24 patients referred for myocardial perfusion imaging [17 males and seven females with a mean age of 58 years, nine of whom had had a previous myocardial infarction (MI)]. Scores were assigned to each of nine myocardial segments for wall motion and for thickening. Cine MRI was analysed in an identical fashion. Four out of 216 (2%) segments were uninterpretable by gated tomography because of inadequate tracer uptake. In eight patients without coronary artery disease (CAD), wall motion and thickening were normal by both methods. Gated tomography showed abnormal wall motion or thickening in all patients with previous MI and in five of seven patients with CAD but no prior MI. Association between wall motion and thickening was good (r s=0.86). Overall, there was good agreement between gated tomography and MRI for both wall motion (178/212 segments, =0.66) and wall thickening (184/212 segments, =0.69). In segments with severely reduced perfusion, however, there was poorer agreement (=0.31). Interobserver and intraobserver agreement was high ( from 0.61 to 0.78). Thus, in patients investigated for CAD, there is good overall agreement between gated tomography and MRI but the agreement is lower in segments with severe perfusion defects.  相似文献   
13.
BACKGROUND: Waldenstrom's macroglobulinemia (WM) is an unusual lymphoplasmacytoid lymphoma characterized by the presence of a serum monoclonal immunoglobulin M. Although several studies have evaluated possible prognostic factors of this disease, few have focused on the survival and prognosis of symptomatic patients after the initiation of treatment. PATIENTS AND METHODS: Our study included 122 previously untreated patients with a median age of 67 years who required systemic treatment. Multiple variables were analyzed for their prognostic value on survival after initiation of treatment using univariate and Cox regression multivariate analysis. RESULTS: The median overall survival was 106 months. Pretreatment factors associated with shorter survival were age >/=65 years, splenomegaly, B-symptoms (weight loss, fever or night sweats), hemoglobin <10 g/dl, platelets <100 x 10(6)/dl, albumin <3.5 g/dl and bone marrow lymphoplasmacytic infiltrate >/=50%. In the multivariate analysis, the two variables with independent prognostic value were age >/=65 years and hemoglobin <10 g/dl. Furthermore, we were able to divide our patients into three risk groups based on the presence of two, one or none of these two adverse prognostic factors. The median survival times in the high-, intermediate- and low-risk groups were 46 months, 107 months and 172 months, respectively (P <0.0001). DISCUSSION: Our findings suggest that advanced age and anemia appear to be the two dominant prognostic factors for survival after initiation of treatment in patients with WM. These two readily available parameters can stratify the patients into three distinct subgroups and may help the selection of appropriate treatment.  相似文献   
14.
When the superficial arm veins are not suitable for the creation of a conventional endogenous arteriovenous (A-V) fistula or the placement of a prosthetic graft in the forearm, the use of the deep forearm veins as an outflow system to construct an A-V graft access seems to be a reasonable alternative. Using this approach, we placed 6 prosthetic grafts in 6 hemodialysis patients in whom conventional methods had failed. Adequate functioning of this 'deep vein'-type vascular access in these 6 patients has been maintained for 3, 6, 11, 15, 19 and 24 months, respectively, without complications or any need for further interventions. Only one graft failed after 6 months. Our preliminary results indicate that this technique can be used successfully when the superficial forearm veins have been exhausted, thus avoiding the use of upper-arm or axillary veins.  相似文献   
15.
PURPOSE: To quantitate the individual levels of melphalan-induced DNA damage formation and repair in vivo and to search for possible correlations with clinical outcome in patients with multiple myeloma (MM). PATIENTS AND METHODS: The formation and subsequent repair of DNA damage (monoadducts and interstrand cross-links) in the p53 tumor-suppressor gene, the proto-oncogene N-ras, and the housekeeping gene beta-actin during the first 24 hours after treatment with high-dose melphalan (HDM; 200 mg/m2) supported by autologous blood stem-cell transplantation (ABSCT) was measured in blood leukocytes of 26 patients with MM. The peak DNA adduct levels, the total amount of adducts over time, and the rate of adducts repair in each gene were correlated with response and time to progression after HDM. RESULTS: The levels of gene-specific DNA damage formation and the individual repairing capacity varied up to 16-fold among patients, indicating that the melphalan-induced biologic effect in vivo is highly individualized. A significantly greater DNA damage and a slower rate of repair in p53 for all end points under study were found in patients who achieved tumor reduction compared with nonresponding patients. Furthermore, longer progression-free survival correlated with increased peak monoadduct levels in the p53 gene (P = .032). CONCLUSION: Increased DNA damage and slower repairing capacity in the p53 gene from blood leukocytes after HDM correlate with improved outcome of patients with MM who undergo ABSCT. These results suggest that quantitation of such biologic end points may identify patients who are more likely to benefit from this procedure.  相似文献   
16.
PURPOSE: Osteonecrosis of the jaw (ONJ) has been associated recently with the use of pamidronate and zoledronic acid. We studied the incidence, characteristics, and risk factors for the development of ONJ among patients treated with bisphosphonates for bone metastases. PATIENTS AND METHODS: ONJ was assessed prospectively since July 2003. The first bisphosphonate treatment among patients with ONJ was administered in 1997. Two hundred fifty-two patients who received bisphosphonates since January 1997 were included in this analysis. RESULTS: Seventeen patients (6.7%) developed ONJ: 11 of 111 (9.9%) with multiple myeloma, two of 70 (2.9%) with breast cancer, three of 46 (6.5%) with prostate cancer, and one of 25 (4%) with other neoplasms (P = .289). The median number of treatment cycles and time of exposure to bisphosphonates were 35 infusions and 39.3 months for patients with ONJ compared with 15 infusions (P < .001) and 19 months (P = .001), respectively, for patients with no ONJ. The incidence of ONJ increased with time to exposure from 1.5% among patients treated for 4 to 12 months to 7.7% for treatment of 37 to 48 months. The cumulative hazard was significantly higher with zoledronic acid compared with pamidronate alone or pamidronate and zoledronic acid sequentially (P < .001). All but two patients with ONJ had a history of dental procedures within the last year or use of dentures. CONCLUSION: The use of bisphosphonates seems to be associated with the development of ONJ. Length of exposure seems to be the most important risk factor for this complication. The type of bisphosphonate may play a role and previous dental procedures may be a precipitating factor.  相似文献   
17.
18.
Background and Aim: We investigated the role of the prophylactic administration of the antioxidant 2‐mercaptoethane sulfonate (mesna) on the hepatocyte‐regenerating capacity following partial hepatectomy (PH) with concurrent Pringle maneuver. Methods: Wistar rats were subjected to PH (70% hepatectomy), 30 min Pringle maneuver, PH plus Pringle with or without mesna pretreatment (400 mg/kg, per os, 3 h before Pringle), or sham operation. At 24 h, 48 h, 72 h, and 1 week after operation, relative liver weight, hepatocyte mitotic activity (mitotic index), the histopathological score and serum aspartate aminotransferase, and alanine aminotransferase concentrations were assessed. At 1 h after operation, oxidative stress markers (glutathione to glutathione disulfide ratio, malondialdehyde concentration, and superoxide dismutase activity) and nuclear factor‐κB (NF‐κB) activity were assessed. Results: Hepatectomy stimulated the regenerating process and induced mild oxidative stress and the activation of NF‐κB in hepatocytes, while causing tissue injury in the remnant liver. When PH was performed under Pringle maneuver, hepatocyte mitotic activity was substantially suppressed, although Pringle alone initiated a delayed regenerating response. Furthermore, Pringle maneuver deteriorated oxidative stress markers, markedly increased NF‐κB activity, and aggravated tissue injury, as compared to hepatectomy alone. Mesna pretreatment prevented the Pringle‐induced antimitotic effect and the induction of oxidative stress, inhibited the activation of NF‐κB, while attenuating liver injury after PH under Pringle. Conclusion: The excessive activation of NF‐κB is related to the suppression of hepatocyte‐regenerating activity following PH with concurrent liver ischemia. Mesna pretreatment protects the liver against the Pringle‐induced antimitotic effect after PH via the prevention of oxidative stress and the inhibition of NF‐κB activation.  相似文献   
19.
20.
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