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   1223篇
  免费   59篇
  国内免费   28篇
耳鼻咽喉   4篇
儿科学   51篇
妇产科学   15篇
基础医学   132篇
口腔科学   24篇
临床医学   86篇
内科学   235篇
皮肤病学   28篇
神经病学   31篇
特种医学   162篇
外科学   124篇
综合类   135篇
预防医学   59篇
眼科学   4篇
药学   86篇
  1篇
中国医学   1篇
肿瘤学   132篇
  2023年   13篇
  2022年   9篇
  2021年   23篇
  2020年   12篇
  2019年   10篇
  2018年   31篇
  2017年   19篇
  2016年   24篇
  2015年   23篇
  2014年   31篇
  2013年   53篇
  2012年   73篇
  2011年   55篇
  2010年   49篇
  2009年   44篇
  2008年   50篇
  2007年   68篇
  2006年   44篇
  2005年   33篇
  2004年   36篇
  2003年   32篇
  2002年   23篇
  2001年   26篇
  2000年   20篇
  1999年   17篇
  1998年   45篇
  1997年   42篇
  1996年   43篇
  1995年   28篇
  1994年   25篇
  1993年   22篇
  1992年   11篇
  1991年   13篇
  1990年   15篇
  1989年   28篇
  1988年   23篇
  1987年   17篇
  1986年   26篇
  1985年   20篇
  1984年   6篇
  1983年   7篇
  1982年   18篇
  1981年   11篇
  1980年   13篇
  1979年   7篇
  1978年   7篇
  1977年   10篇
  1976年   12篇
  1975年   9篇
  1974年   6篇
排序方式: 共有1310条查询结果,搜索用时 15 毫秒
91.
黄柏及中成药中小檗碱和巴马亭的高效液相色谱法测定   总被引:6,自引:0,他引:6  
本文以正相高效液相色谱法,用窗口图解技术对色谱条件进行了优化。对黄柏及其中成药中的有效成分——小檗碱、巴马亭的提取、测定条件、标准曲线进行了研究。并对两种含黄柏的中成药样品进行了分析。其中小檗碱的回收率均在97%以上,巴马亭的回收率均在96%以上。  相似文献   
92.
93.
O'Connor  MK; Brennan  SS; Shanik  DG 《Radiology》1986,158(1):191-194
The incidence of thromboembolitic events in patients undergoing transfemoral angiography was examined using indium-111 labeled platelets. Twenty-seven patients received approximately 300 muCi of autologous labeled platelets at least 3 hours before angiography and were scanned with a gamma camera immediately before and after angiography. All patients were free of clinically obvious complications in the 1-2 day period after angiography. Our results showed evidence of platelet deposition at 21 sites other than the puncture site in 12 (44%) patients. Most platelet deposition (54%) occurred along the region between the puncture site and the aortic bifurcation; 24% occurred at sites not traversed by the catheter. At the puncture site itself, there was substantial platelet uptake in 44% of patients. This study indicates the need for further work in determining the most suitable catheter material and in assessing the efficacy of other measures such as anticoagulant or antiplatelet therapy.  相似文献   
94.
老年大鼠松质骨骨重建的组织形态计量学研究   总被引:1,自引:0,他引:1  
目的:研究老年大鼠及在促骨合成药前列腺素E2(PGE2)作用下松质骨骨重建和骨建造的形态计量学改变,探讨动物骨重建形态学新参数测量方法及其意义。方法:50只20月龄雄性Wistar大鼠随机分成5组,年龄对照组(基础组、10d和30d年龄对照组),PGE2给药组(分别10d和30d给予3mg/kg/d处理组)。用体内双荧光标记,不脱钙组织切片,粘合线(cement line)染色,骨组织形态计量学方法,测定骨重建和骨建造参数。结果:20月龄雄性大鼠胫骨近端松质骨的形成表面大多数为骨重建单位(占63.3%),少部分为骨建造单位(占26.7%);PGE2用药后骨重建单位增加1.5倍,骨建造单位增加4倍,比值倒置,成骨细胞10d时明显增多。说明PGE2通过刺激成骨细胞骨合成而介民导骨建造性骨增加和骨重建性骨量增加,并以前为主。结论:老年雄性大鼠 松质骨以骨重建活动为主,仍有骨建造活动。PGE2主要通过刺激成骨细胞骨建造而增加骨量。  相似文献   
95.
Background: Estimates of the incidence of venous thrombosis (VT) vary, and data on mortality are limited. Objectives: We estimated the incidence and mortality of a first VT event in a general population. Methods: From the residents of Nord‐Trøndelag county in Norway aged 20 years and older (n = 94 194), we identified all cases with an objectively verified diagnosis of VT that occurred between 1995 and 2001. Patients and diagnosis characteristics were retrieved from medical records. Results: Seven hundred and forty patients were identified with a first diagnosis of VT during 516 405 person‐years of follow‐up. The incidence rate for all first VT events was 1.43 per 1000 person‐years [95% confidence interval (CI): 1.33–1.54], that for deep‐vein thrombosis (DVT) was 0.93 per 1000 person‐years (95% CI: 0.85–1.02), and that for pulmonary embolism (PE) was 0.50 per 1000 person‐years (95% CI: 0.44–0.56). The incidence rates increased exponentially with age, and were slightly higher in women than in men. The 30‐day case‐fatality rate was higher in patients with PE than in those with DVT [9.7% vs. 4.6%, risk ratio 2.1 (95% CI: 1.2–3.7)]; it was also higher in patients with cancer than in patients without cancer [19.1% vs. 3.6%, risk ratio 3.8 (95% CI 1.6–9.2)]. The risk of dying was highest in the first months subsequent to the VT, after which it gradually approached the mortality rate in the general population. Conclusions: This study provides estimates of incidence and mortality of a first VT event in the general population.  相似文献   
96.
The purpose of this study was to develop and test the Role-Related Meaning Scale for Staff in Pediatric Oncology (RRMS) to determine the internal consistency and the content and construct validity of this two-phase instrument. During phase 1 (item generation, content validation, and initial field testing), 23 nurses from two cancer centers participated, and during phase 2 (instrument testing), 89 nurses from one pediatric research center participated. The nurses completed either the RRMS only (phase 1) or six instruments including the RRMS (phase 2) to assess the following research variables: role-related meaning, group cohesion, organizational commitment, work satisfaction, and intent to leave. The RRMS was revised after phase 1 because the results yielded a ceiling effect and three overlapping items. The Cronbach alpha for the phase 2 total RRMS was.83, and four of the five hypothesized relations were confirmed (P =.04). Therefore, the RRMS was concluded to be an internally consistent instrument that has content validity and beginning construct validity. Future studies will examine whether the RRMS adequately measures the change in meaning brought about by interventions designed to increase role-related meaning among nurses.  相似文献   
97.
对QT离散度实质的探讨   总被引:2,自引:0,他引:2  
为探讨QT离散度(QTd)的真实意义,观察139例急性心肌梗死(AMI,AMI组)及109例正常人(对照组)的最长QT间期(QTmax)、校正QTmax(QTcmax)及QTd的变化。结果:①AMI组的QTmax、QTcmax和QTd均显著高于对照组(分别为422.60±30.51msvs382.46±23.40ms、460.21±28.96msvs388.51±20.15ms、59.80±28.40msvs39.43±12.21ms,P均<0.001)。②AMI组中发生严重室性心律失常(VA)患者(114例)的QTmax、QTcmax、QTd与无VA的患者(25例)相比,均有显著差异(分别为448.58±33.40msvs416.10±35.30ms、481.43±35.17msvs439.60±27.10ms、66.90±20.72msvs48.32±23.61ms,P均<0.001)。认为AMI时QTd系T向量环在不同导联上的“投影”差异所引起的,其异常的本质是QT间期延长  相似文献   
98.
99.
Rous sarcoma virus group antigen protein-based virus-like particles (VLPs) are well known for their structural integrity and ease of handling. VLPs play an important role in drug delivery systems because they can be manipulated with ease. In this study, a new method was established for expressing Rous sarcoma virus group antigen protein based VLPs in silkworm larvae and establishing stably expressing insect cell lines. These VLPs have been isolated by ultracentrifugation using a sucrose step gradient of 10–60% (v/v), and their spherical structure has been confirmed using transmission electron microscopy (TEM). The spherical morphology is similar in both the silkworm larvae and in stably expressing cell lines. Silkworm larvae are better suited for producing Rous sarcoma virus group antigen protein-based VLPs on a large scale; yields from silkworm larvae were approximately 8.2-fold higher than yields from stable cell lines. These VLPs provide a new method for large-scale application in vaccine development and drug delivery systems.  相似文献   
100.
Carcinoma of the cervix is the most common malignancy among women in India. Although metastatic disease is common, metastasis to breast is rare. A limited number of case reports are published in the world literature. Most of the previous reports of metastatic cervical carcinoma to breast are either autopsy series or widely disseminated disease where no treatment options were available. A rare case of cervical carcinoma presenting as metastasis in breast is reported here where palliative mastectomy improved the general condition of the patient. A female patient aged 58 years was diagnosed and treated for cervical carcinoma, FIGO stage 2B. Four months after the treatment which included both external beam and intracavitory radiotherapy, the patient presented with breast and lung metastasis. Palliative mastectomy was done which improved the general condition of the patient. Metastatic carcinoma of the cervix can present as a case of breast carcinoma. In an appropriate setting, this possibility should be kept in mind. Palliative mastectomy should be offered for patients of cervical carcinoma with metastasis to breast when needed.  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