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   955篇
  免费   53篇
  国内免费   3篇
耳鼻咽喉   7篇
儿科学   24篇
妇产科学   24篇
基础医学   77篇
口腔科学   32篇
临床医学   137篇
内科学   232篇
皮肤病学   83篇
神经病学   19篇
特种医学   3篇
外科学   175篇
综合类   30篇
一般理论   1篇
预防医学   51篇
眼科学   8篇
药学   70篇
中国医学   23篇
肿瘤学   15篇
  2022年   3篇
  2021年   6篇
  2019年   6篇
  2018年   7篇
  2017年   16篇
  2016年   14篇
  2015年   30篇
  2014年   45篇
  2013年   48篇
  2012年   32篇
  2011年   23篇
  2010年   101篇
  2009年   123篇
  2008年   43篇
  2007年   34篇
  2006年   58篇
  2005年   22篇
  2004年   5篇
  2003年   13篇
  2002年   9篇
  2001年   3篇
  2000年   3篇
  1999年   9篇
  1998年   23篇
  1997年   48篇
  1996年   47篇
  1995年   28篇
  1994年   19篇
  1993年   19篇
  1992年   15篇
  1991年   16篇
  1990年   11篇
  1989年   10篇
  1988年   6篇
  1987年   13篇
  1986年   8篇
  1985年   2篇
  1984年   10篇
  1983年   7篇
  1981年   4篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1975年   2篇
  1959年   9篇
  1958年   17篇
  1957年   9篇
  1956年   9篇
  1955年   2篇
  1954年   9篇
排序方式: 共有1011条查询结果,搜索用时 562 毫秒
11.
12.
Mechanical femoral artery compression devices have several limitations. We compared a novel disposable beltheld pneumatic compression device to manual compression alone in 213 patients randomized into two equal groups. Both were comparable for age, gender, current therapy with aspirin (ASA) and warfarin, diameter of the arterial sheath, previous procedures via the same artery, procedure duration, and blood pressure. Manual compression time was 12 ± 3 minutes. Pneumatic compression was reduced during 60 minutes. Patient discomfort was assessed as none (82% vs 88%), mild (13% vs 8%), moderate (3% vs 4%), or severe (2% vs 0%) for the manual versus pneumatic group, respectively. Bleeding and hematoma occurred in 7.5% of patients with no difference between the treatment groups. However, manual compression was significantly more effective in the higher range of systolic blood pressure, and pneumatic in the lower range, with a cut point of approximately 170 mmHg. Predictors for bleeding were systolic blood pressure and dose of ASA. Among 113 patients with systolic blood pressure < 160 mmHg and low dose (75 mg) or no ASA, only / patient (0.9%) experienced bleeding while 31% of 16 patients with both elevated systolic blood pressure and high dose ASA (150–330 mg) bled. We conclude that pneumatic femoral artery compression does not reduce bleeding and hematoma compared with manual compression. The use of low dose (75 mg) or no ASA, as well as giving special attention to patients with elevated systolic blood pressure, may reduce the risk of bleeding after cardiac catheterization .  相似文献   
13.
The most common cause of death in patients with colorectal cancer is metastatic liver disease. In order to identify patients at a high risk of developing hepatic secondaries from colorectal cancers, DNA content was measured in metastasizing colorectal primaries (Group I, n= 32) as well as in their subsequently resected liver secondaries and in sections of non-metastasizing colorectal cancers (Group II, n= 25). A modified interpretation system involving both a DNA index and percentage of cycling cells (those in S and G2 + M phases) was developed. DNA content was measured in paraffin-embedded sections by flow cytometry using internal controls (human peripheral blood mononuclear cells) and non-malignant tissue controls (19 patients with diverticular disease). In Group I there were significantly more tumours with both abnormal ploidy (aneuploid or abnormal tetraploid peak) and > 15% cycling cells compared with Group II (Chi-squared; P= 0.034). The combination of abnormal ploidy and > 15% cycling cells was superior to Dukes’ classification for identifying metastasizing tumours (Logistic Regression; P= 0.047). However, it was not possible to discriminate between the two groups using either DNA ploidy or the percentage of cycling cells alone. The metastasizing colorectal cancers exhibited similar DNA ploidy characteristics and had a similar percentage of cycling cells compared with their liver metastases. These results suggest that tumour DNA ploidy plus the percentage of cycling cells may predict the development of liver metastases and thus survival in patients with colorectal cancer.  相似文献   
14.
We investigated the efficacy of methadone maintenance treatment in clinic-based (n= 10) and community-based (n= 10) patients by studying the relationships between dose, plasma concentrations of methadone and non-prescribed drug-use using logistic regression. We found that clinic-based patients had significantly reduced odds of having a urine sample test positive for illicit drugs when compared to community-based patients (OR = 0.20; 95% confidence interval 0.10–0.38: p < 0.001). There was no relationship between either methadone dose or plasma methadone concentration and testing positive for non-prescribed drugs (including cocaine, cannabis, amphetamine, ecstasy, benzodiazepines). We looked specifically at the misuse of opiate drugs. Location was again important and clinic-based patients had significantly reduced odds of having a urine sample test positive for opiate drugs (OR= 0.36, 95% confidence internal 0.13–0.71: p~0.004). Opiate drug use in our patients was also significantly related to plasma methadone concentration, increasing noticeably when the drug concentration < 0.48 nmol/L (p~0.04). We found no relationship between methadone dose and odds of having a positive urine drug test in either clinic- or community-based patients.  相似文献   
15.
Suppression of Humoral Immune Responses by Dialkylnitrosamines:Structure-Activity Relationships. KAMINSKI, N. E., JORDAN, S.D., PAGE, D., KIM, B. S., AND HOLSAPPLE, M. P. (1989). Fundam.Appl Toxicol 12,321-332. Comparisons between chemical structureof N, N-dialkylnitrosamine congeners and their ability to alterthe Day 4 IgM antibody response to sRBC, body weights. and organweights of female B6C3F1 mice were investigated. Short-chainnitrosamine congeners were selected for these studies on thebasis of two criteria: (1) congeners wth symmetrical aliphaticchain length [N-nitrosodimethylamine (DMN), N-nitrosodiethylamine(DEN), N-nitrdipropylamine (DPN), N-nitrosodibutylamine (DBN)]and (2) congeners possessing an N-methyl group [N-nitrosomethylethylamine(MEN), N-nitrosomethylpropylamine (MPN), and N-nitrosomethylbutylamine(MBN)]. The immunotoxicity of each congener was evaluated basedon the compound's ability to suppress the in vivo sRBC antibodyresponse following 7 consecutive days of treatment. An ED50dose was calculated, using a linear regression analysis, foreach congener and represents the millimoles of congener perkilogram body weight required to cause a 50% suppression ofthe sRBC response. These studies demonstrated two general trends:(1) those dialkylnitrosamine congeners that possessed an N-methylgroup were most immunotoxic and exhibited comparable ED50 concentrations(42-183 µmol/kg); and (2) dialkylnitrosamine congenerspossessing symmetrical aliphatic chains demonstrated an inverserelationship between aliphatic chain length and immunotoxicpotency—DMN (62 µmol/kg) > DEN (276 µmol/kg)> DPN (467 µmol/kg) > DMN (1557 µmol/kg).Comparisons were also made between the immunotoxic potency ofvarious nitrosamine congeners in the whole animal and theirpotency in an in vitro hepatocyte-spleen cell coculture system.  相似文献   
16.
ABSTRACT: A Male rabbit was immunized with rat testicular cytochrome (Cyt) ct and mated with normal, unimmunized females. The matings resulted in abnormal pregnancies: no offspring or stillborn or undersized liveborn offspring weighing 25–30 gm each. Another unusual observation was that fur-pulling behavior, normally exhibited by pregnant female rabbits at the end of the gestational period, was absent in all of these pregnancies. Therefore, immunization of a normal rabbit with testicular cyt ct appeared to interfere with physiological and behavioral aspects of pregnancy in normal female rabbits. The immunological basis of these findings remains to be determined.  相似文献   
17.
We investigated the effects of 12‐hour shift work for five to seven consecutive days and overtime on the prevalence of severe sleepiness in the automobile industry in Korea. [Correction added after online publication 28 Nov: Opening sentence of the summary has been rephrased for better clarity.] A total of 288 randomly selected male workers from two automobile factories were selected and investigated using questionnaires and sleep‐wake diaries in South Korea. The prevalence of severe sleepiness at work [i.e. Karolinska Sleepiness Scale (KSS) score of 7 or higher] was modeled using marginal logistic regression and included theoretical risk factors related to working hours and potential confounding factors related to socio‐economic status, work demands, and health behaviors. Factors related to working hours increased the risk for severe sleepiness at the end of the shift in the following order: the night shift [odds ratio (OR): 4.7; 95% confidence interval (CI): 3.6–6.0)], daily overtime (OR: 2.2; 95% CI: 1.7–2.9), weekly overtime (OR: 1.6; 95% CI: 1.0–2.6), and night overtime (OR: 1.6; 95% CI: 0.8–3.0). Long working hours and shift work had a significant interactive effect for severe sleepiness at work. Night shift workers who worked for 12 h or more a day were exposed to a risk of severe sleepiness that was 7.5 times greater than day shift workers who worked less than 11 h. Night shifts and long working hours were the main risk factors for severe sleepiness among automobile factory workers in Korea. Night shifts and long working hours have a high degree of interactive effects resulting in severe sleepiness at work, which highlight the need for immediate measures to address these characteristics among South Korean labor force patterns.  相似文献   
18.
子宫颈癌△Np63蛋白表达的临床病理学意义   总被引:1,自引:1,他引:1  
目的探讨△Np63蛋白表达在子宫颈癌不同组织学类型中的临床病理学意义。方法43例子宫颈上皮内瘤变(cervi-calintraepithelialneoplasia,CIN)(包括15例CIN1,6例CIN2和22例CIN3),21例角化型和33例大细胞非角化型宫颈鳞状细胞癌(鳞癌)、40例腺癌、4例神经内分泌癌、4例腺鳞癌、2例移行细胞癌、2例玻璃样细胞癌和1例腺瘤样基底细胞癌的标本选自韩国高丽大学安岩附属医院和延边妇幼保健医院病理科,应用免疫组化染色方法检测△Np63蛋白在上述病变组织中的表达情况。结果△Np63蛋白在所有子宫颈鳞癌标本中呈阳性表达,而在所有腺癌则为阴性。随着CIN病变级别的增加,△Np63蛋白表达的分布范围也逐渐增多,而且在不同组织学类型的子宫颈癌中,合并鳞状细胞分化(associatedwithsquamousdifferentiationofuterinecervix)的病变区△Np63表达增强,但在腺性分化和神经内分泌分化的区域△Np63则不表达。结论△Np63蛋白检测对区分子宫颈癌组织学类型的具有重要意义,且对子宫颈腺癌的鉴别诊断是一个非常有用的指标。  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