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   1395篇
  免费   70篇
  国内免费   3篇
耳鼻咽喉   10篇
儿科学   41篇
妇产科学   19篇
基础医学   189篇
口腔科学   33篇
临床医学   95篇
内科学   358篇
皮肤病学   26篇
神经病学   157篇
特种医学   21篇
外科学   108篇
综合类   14篇
一般理论   1篇
预防医学   92篇
眼科学   31篇
药学   144篇
中国医学   10篇
肿瘤学   119篇
  2024年   3篇
  2023年   14篇
  2022年   33篇
  2021年   50篇
  2020年   39篇
  2019年   28篇
  2018年   31篇
  2017年   18篇
  2016年   40篇
  2015年   32篇
  2014年   47篇
  2013年   74篇
  2012年   102篇
  2011年   110篇
  2010年   56篇
  2009年   40篇
  2008年   62篇
  2007年   81篇
  2006年   76篇
  2005年   71篇
  2004年   97篇
  2003年   90篇
  2002年   104篇
  2001年   17篇
  2000年   8篇
  1999年   14篇
  1998年   19篇
  1997年   14篇
  1996年   11篇
  1995年   10篇
  1994年   9篇
  1993年   11篇
  1992年   11篇
  1991年   5篇
  1990年   7篇
  1989年   2篇
  1987年   3篇
  1986年   2篇
  1984年   2篇
  1983年   7篇
  1982年   2篇
  1981年   2篇
  1980年   6篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1974年   1篇
  1971年   1篇
  1970年   1篇
  1968年   1篇
排序方式: 共有1468条查询结果,搜索用时 0 毫秒
71.
A cross-sectional questionnaire study was carried out on nursery school (NS) teachers in public nursery schools in N city in Japan to determine the magnitude of associations of probable risk factors with neck, shoulder, and arm pain, adjusting for potential confounders in logistic regression models. Of 1438 subjects, responded to the questionnaire, 959 NS teachers in charge of a separate or mixed group of children were subjected to analyses. Prevalence of neck and/or shoulder pain was 33.6%-35.4% in NS teachers in charge of children aged 0, 0-1, 4, and 5 in contrast to 25.0-29.8% in those in charge of children aged 1,2, and 3. The prevalence of neck/shoulder pain tended to increase with the length of employment in all groups classified according to the age of children under care. In a logistic regression model that simultaneously adjusted demographic and personal variables, length of employment and care for children aged 0 in the workplace were found significantly associated with musculoskeletal pain. In further logistic models, pain in the neck/shoulders and arms had associations with some specific variables: care for children aged 0, holding/lifting a child/material, overwork, and poorly supported job situations. The odds ratios for those variables varied from 1.37 to 2.41. This results suggest that pain in the neck/shoulders and arms is induced by a wide variety of risk factors in NS teachers that include high physical workload, long working hours, job demand-support imbalance, and cumulative influence of workloads.  相似文献   
72.
Following a transient ischemic insult there is a marked increase in free radical (FR) production within the first 10-15 min of reperfusion and again at the peak of the inflammatory process. Hypothermia decreases lipid peroxidation following global ischemia, raising the possibility that it may act by reducing FR production early on and by maintaining or increasing endogenous antioxidant systems. By means of FR fluorescence, Western blot, immunohistochemistry, and enzymatic assay, we studied the effects of mild hypothermia on superoxide (O(-*)(2)) anion production, superoxide dismutase SOD expression, and activity following focal cerebral ischemia in rats. Mild hypothermia significantly reduced O(-*)(2) generation in the ischemic penumbra and corresponding contralateral region, but did not alter the bilateral SOD expression. SOD enzymatic activity in the ischemic core was slightly reduced in hypothermia-treated animals compared with normothermic controls. Our results suggest that the neuroprotective effect of mild hypothermia may be due, in part, to a reduction in neuronal and endothelial O(-*)(2) production during early reperfusion.  相似文献   
73.
Association between clinical characteristics and types of the tau gene mutation has been observed in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). P301L mutation seldom causes parkinsonism as a leading symptom; instead it usually causes personality changes with aggressiveness and disinhibition. We experienced two patients of FTDP-17 from separate families (designated as patient 1 from family 1 and patient 2 from family 2). They had P301L mutation in common. However, their phenotypes were distinct from each other. Aggressive behaviors and disinhibition were the main symptoms in patient 1, whereas parkinsonism was the most prominent feature in patient 2. Their genotypes of the tau gene were different at three sites, i. e. in exon 6, in intron segment before exon 10, and in exon 13, though they do not bring amino acid change. Patient 1 had more prevalent C/C, C/C, and rare T/C respectively. Patient 2 had less prevalent T/T, A/A, and more prevalent T/T respectively. These findings suggest two things. Firstly, they do not share a common founder for P301L mutation. Secondly, either of the two less prevalent genotypes observed in patient 2 may be the factor to modify the phenotype of P301L mutation into those unusual clinical features with prominent parkinsonism. Accumulation of information as to phenotype-genotype association will settle this hypothesis. Received: 7 May 2001, Received in revised form: 23 October 2001, Accepted: 22 November 2001  相似文献   
74.
Factor VIII (FVIII) inhibitor alloantibodies react with the A2, C2, or A3-CI domains of FVIII and inactivate FVIII activity. We recently demonstrated that an anti-C2 monoclonal antibody with a Val2248-Gly2285 epitope, inhibited factor Xa (FXa)-catalyzed FVIII activation, and that a FXa binding site for FVIII was located within residues Thr2253-Gln2270. In this study, we investigated whether anti-C2 alloantibodies inhibit FXa-catalyzed FVIII activation. Anti-C2 alloantibodies from four patients inhibited FVIII activation by FXa in one-stage clotting assay. Furthermore, analysis by SDS-PAGE showed that all alloantibodies inhibited FVIII proteolytic cleavage by FXa independently of phospholipid. To confirm direct inhibition of FVIII and FXa interaction, we examined the effect of alloantibodies on FVIII binding to anhydro-FXa, a catalytically inactive FXa, in ELISA. All alloantibodies and C2-affinity purified F(ab)'2 preparations inhibited FVIII binding to anhydro-FXa dose-dependently. Our results revealed a new inhibitory mechanism of FVIII, mediated by inhibition of FXa in the presence of anti-C2 alloantibodies.  相似文献   
75.
Protein-L-isoaspartyl methyltransfearase (PIMT) plays a physiological role in the repair of damaged proteins containing isoaspartyl residues. In previous studies, we showed that PIMT-deficient mice developed a fatal epileptic seizure associated with the accumulation of damaged proteins in the brain. The mutant mice also showed a neurodegenerative pathology in hippocampi and impaired spatial memory. Still undefined, however, is how the accumulation of isoaspartates leads to the death of PIMT-deficient mice. In the present study, we generated PIMT transgenic (Tg) mice to investigate whether the exogenous expression of PIMT could improve the symptoms associated with PIMT deficiency. Rescue experiments showed that Tg expression of PIMT driven by a prion promoter effectively cured the PIMT-deficient mice. Biochemically, a higher expression level of transgene led to the effective repair of damaged proteins in vivo. Although a lower level of expression caused an accumulation of damaged proteins in a partially rescued line, the mice survived. Interestingly, synapsin I, which was extensively modified posttranslationally in PIMT-deficient mice, was specifically repaired in a partially rescued, but symptom-improved, Tg line. Our results suggest that an overall accumulation of damaged proteins does not necessarily lead to a fatal epileptic seizure, whereas certain modifications, such as changes in synapsin I, may play a pivotal pathological role in epilepsy.  相似文献   
76.
OBJECTIVE: We surmised that increase in stress in mothers having infants might be due to decline of social support under circumstances where nuclear family households now predominate. The present study was therefore conducted to analyze relations between stress reactions of mothers having infants, their recognition of social support, and negative feelings toward their baby and child care, a major factor in the burden of childcare. METHODS: The subject were 909 mothers having infants in nuclear families who lived in I city in Osaka Prefecture. Health examinations of infants at the ages of 4 months, 1 year and 6 months, and 3 years and 6 months were utilized. Questionnaires titled "Survey on Childcare" were distributed in advance by mail to parents of the infants included in the health examinations and collected at the health examinations. The survey period was August to September 2000. Personal background variables and, psychological investigation items, including mental health in terms of stress reactions, negative feelings toward childcare as a factor in the burden of childcare, and a support network scale were surveyed and analyzed. RESULTS: The mothers with infants were judged to be in a stressful state from the average mental health scores in all groups. Multiparas had significantly higher negative feelings toward childcare scores. Regarding the age groups of children, a significantly decreasing recognition of a support network as well as significantly increasing negative feelings toward childcare were observed with the growth of children. There was a positive correlation between negative feelings toward childcare and stress reactions. The recognition of social support was negatively correlated with stress reactions and negative feelings toward childcare. CONCLUSION: The study revealed that mothers having infants are in a stressful state and that the recognition of stress is related to negative feelings toward childcare and the recognition of a support network. The feeling of sufficient support lowers the level of stress arising from childcare, and facilitates avoiding or coping with problems, thereby promoting mothers' physical and mental health. This is important for continuation and fulfillment of childcare.  相似文献   
77.
PURPOSE: The relationship of activities of daily living (ADL) with daily habits and age was investigated with a focus on the results of measurements of the normal speed (ordinary level: OL) and maximum speed (maximum capacity: MC) in performing items on a functional fitness test. The significance of the measurement of the ordinary level was also discussed. METHODS: The subjects were 69 women, aged 60-90 years old, who participated in a health workshop for the elderly sponsored by a local municipality and who performed at least 4 items on a functional fitness test. Public health nurses asked subjects about habitual life style, subjective health status and degree of satisfaction in daily life. The ADL level was measured using the tests of functional fitness developed by Oida et al and partially revised by ourselves and physical fitness tests (grip strength, sit and reach, and balancing on one leg with opened eyes). OL was measured as the time needed to perform functional fitness items at normal speed, and MC as the time needed when performing these tasks as quickly as possible. RESULTS: All functional fitness items were accomplished significantly faster with MC than OL. Correlation coefficient values between OL and MC were high significant. Age was found to be significantly related to the hand working test (Hand-T) to evaluate dexterity and the rope working test (Rope-T) to evaluate self-care, except with the MC. An analysis of covariance with age as the covariant revealed that, with OL, there were relationships between Hand-T and Rope-T and the item "active at home," and between the zigzag walking (Zigzag-T) and Rope-T and "walking or riding a bicycle to go shopping." With MC, there were relationships between Hand-T and "active at home," and between Zigzag-T and "walking of riding a bicycle to go shopping." Regarding physical capacity, relationships were seen between both hands and "high level of physical fitness" and "walking fast" and grip strength (Left hand), respectively. CONCLUSION: The ADL items measured in the preset study were related to the daily activities of elderly people. As the OL and MC results demonstrated a high correlation and the ADL items related with OL were found to have almost the same link with MC, we conclude that OL is suitable for testing with the advantage of safety. However, we could not explain differences in relationships between measurements and daily activities, pointing to a need for further research. Elderly people must maintain their capacity for ADL to support a good quality of life, and we have demonstrated the utility of measurements that include normal levels of activity as indicators.  相似文献   
78.
Objectives: The purpose of this study was to investigate the serological risk factors for development of adult T-cell leukemia/lymphoma (ATL) among human T-cell lymphotropic virus type-I (HTLV-I) carriers. Methods: A nested case–control study was performed. The source population comprised 23,922 subjects who had either visited the outpatient clinic or who had received annual health check-ups at the K Hospital, Nagasaki, Japan, at least once during 1985–1996 (HTLV-I seroprevalence = 16.1%). Markers of HTLV-I infection were examined in stored sera from 29 incident cases of ATL diagnosed during 1985–1997, and 158 controls matched for sex, birth year, date of sample collection, and HTLV-I seropositivity (median follow-up = 6.4 years). Results: In exact conditional logistic regression analysis, high levels of soluble interleukin-2 receptor ( 500 U/ml) and high HTLV-I antibody titers ( 1024) were independently associated with an increased risk of developing ATL (Odds ratio 20.5, 95% confidence interval (CI) 4.5–194 and 2.9, 95% CI 0.98–9.5, respectively). The results remained essentially unchanged when the subjects were restricted to those whose histories were followed for two years or longer. Conclusions: These findings indicate that high soluble interleukin-2 receptor levels and high HTLV-I antibody titers are strong predictors of ATL among carriers of HTLV-I.  相似文献   
79.
The natural cembranolide sarcophine (3) and its lactone ring-opened analogue (10) were oxidized using selenium dioxide under different reaction temperatures to prepare hydroxylated derivatives. Nine new compounds were obtained, six of them targeted hydroxylated derivatives. The determination of regio- and stereochemistry as well as the mechanistic considerations on the selectivity observed in these reactions are discussed on the basis of 2D NMR and molecular modeling. In preliminary in vitro tests on inhibition of EBV-EA activation, compounds 10 and 12-15 have shown higher activity than the known chemopreventive agent sarcophytol A.  相似文献   
80.
Inappropriate exposure to estrogens in the fetal and/or newborn period can exert irreversible influence, including carcinogenesis on the reproductive system in mammals. The present study was conducted to investigate uterine carcinogenesis in Donryu rats treated neonatally with a high-dose estrogenic compound, p-t-octylphenol (OP) for different exposure periods. Female Donryu rats were subcutaneously administered 100 mg/kg/day OP every other day for the first 5 postnatal days (PNDs 1-5) or the first 2 weeks (PNDs 1-15). They received a single injection of 20 mg/kg N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) into a uterine horn at 11 weeks of age and were examined until 15 months of age. PNDs 1-5 OP-treated rats showed normal development of the female reproductive system, including uterine gland genesis and normal estrous cycling after vaginal opening. The treatment, however, accelerated an earlier occurrence of persistent estrus and increased the number of well differentiated uterine adenocarcinomas as compared with controls. This indicated that PNDs 1-5 OP treatment acts as a delayed modulator of the hypothalamus-pituitary-ovarian hormonal control system and the modulation increased the serum estrogen:progesterone ratio, resulting in induction of uterine tumors. On the contrary, PNDs 1-15 OP treatment demonstrated immediate and irreversible influences on the control system, called 'androgenization', and induced abnormal uterine development manifested by prolonged persistent estrus immediately after vaginal opening and also suppression of uterine gland genesis. In addition, uterine tumor malignancy in morphological and biological property clearly increased in this group although the total number of adenocarcinomas was not increased. The present study provides evidence that neonatal exposure to a high-dose OP enhances uterine carcinogenesis in rats, and the type of uterine tumors is changed by the periods of neonatal exposure to OP, suggesting that the mechanism of uterine tumor development is dependent upon neonatal exposure periods.  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