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   1302篇
  免费   70篇
  国内免费   6篇
耳鼻咽喉   10篇
儿科学   34篇
妇产科学   16篇
基础医学   167篇
口腔科学   32篇
临床医学   100篇
内科学   380篇
皮肤病学   40篇
神经病学   105篇
特种医学   40篇
外科学   90篇
综合类   8篇
一般理论   1篇
预防医学   92篇
眼科学   36篇
药学   119篇
肿瘤学   108篇
  2024年   1篇
  2023年   11篇
  2022年   18篇
  2021年   21篇
  2020年   18篇
  2019年   14篇
  2018年   22篇
  2017年   30篇
  2016年   30篇
  2015年   29篇
  2014年   40篇
  2013年   69篇
  2012年   95篇
  2011年   83篇
  2010年   60篇
  2009年   43篇
  2008年   92篇
  2007年   80篇
  2006年   107篇
  2005年   91篇
  2004年   103篇
  2003年   100篇
  2002年   84篇
  2001年   11篇
  2000年   7篇
  1999年   12篇
  1998年   14篇
  1997年   13篇
  1996年   3篇
  1995年   8篇
  1994年   6篇
  1993年   3篇
  1992年   2篇
  1991年   6篇
  1990年   3篇
  1989年   8篇
  1988年   4篇
  1987年   3篇
  1986年   5篇
  1985年   1篇
  1984年   9篇
  1983年   5篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   4篇
  1976年   1篇
  1972年   2篇
  1964年   1篇
排序方式: 共有1378条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: Gut hypoperfusion is considered to be a mechanism for early multiple‐organ failure after severe surgical insults. L‐Arginine (ARG) may preserve gut microcirculation as a substrate of nitric oxide synthase, but simultaneously may enhance immune cell response. It remains unknown if ARG infusion during gut ischemia improves the outcome after gut ischemia‐reperfusion (I/R). METHODS: Male Institute of Cancer Research mice were randomized to control and ARG groups. After i.v. cannulation, mice underwent 90 (Exp. 1) or 60 (Exp. 2 and 3) minutes of gut I/R. Control mice received normal saline infusion at 1 mL/h for 60 minutes during ischemia, whereas the ARG group was given 1% ARG hydrochloride solution. In Exp. 1, survival was observed for 72 hours (n = 35). In Exp. 2, blood perfusion and oxygen tension of the small intestine were measured (n = 9). In Exp. 3, peripheral blood was obtained at 2 or 4 hours after reperfusion (n = 22). Reactive oxygen intermediate (ROI) production by myeloid cells with or without phorbol myristate acetate (PMA) stimulation and expression of CD11a and CD11b on myeloid cells were examined using flow cytometry. RESULTS: Exp. 1: There was no significant difference in survival times (log rank test, p =.2). However, survival rates at 12 hours were 72% (13/18) for the control group and 35% (6/17) for the ARG group (p <.05 Fisher). Exp. 2: ARG infusion significantly improved gut blood perfusion ratio during ischemia but had no effect on oxygen tension. Exp. 3: In the ARG group, ROI production with PMA and CD11b expression at 4 hours were higher than those at 2 hours, whereas there were no significant changes in the control mice. CONCLUSIONS: ARG infusion improves intestinal blood perfusion during ischemia but primes and activates circulating myeloid cells excessively. Consequently, i.v. infusion of ARG during ischemia reduces survival rate.  相似文献   
82.
BACKGROUND: Experimentally, total parenteral nutrition (TPN) diminishes gut-associated lymphoid tissue (GALT) cell numbers and function. Although glutamine supplementation is known to reverse TPN-induced changes in GALT, effects of another conditionally essential amino acid, L-arginine (ARG), on GALT remain unclear. METHODS: Twenty-two male Institute of Cancer Research mice were randomized to standard TPN (0.3% arginine, STD-total parenteral nutrition) or 1% ARG-enriched TPN (ARG-total parenteral nutrition). After 5 days of feeding, lymphocytes were harvested from Peyer's patches (PP), the lamina propria, and intraepithelial (IE) spaces of the small intestine to determine cell yields. Lymphocyte phenotypes (alphabetaTCR, gammadeltaTCR, CD4, CD8, and B220 as a B cell marker) were determined using flow cytometry. IgA levels in washings of the small intestine, upper respiratory tract, and lungs were measured with ELISA. RESULTS: ARG-total parenteral nutrition did not affect lymphocyte yields. The percentages of CD4+ cells in PP and IE, and alphabetaTCR+ cells in PP, were significantly higher in the ARG-total parenteral nutrition than in the STD-total parenteral nutrition mice, without marked differences in other phenotypes examined. There were no significant differences in intestinal and respiratory tract IgA levels between the 2 groups of mice. CONCLUSIONS: One percent ARG supplementation of TPN does not improve GALT cell number or mucosal IgA level but benefits to increase CD4+ cell percentages in GALT.  相似文献   
83.
ABSTRACT  The phenotype of the genetic polydactyly/arhinencephaly mouse (Pdn/Pdn) is similar to Greig cephalopolysyndactyly syndrome (GCPS), whose responsible gene is GLI3. Suppression of Gli3 gene expression has been observed in the Pdn/Pdn and integration of retrotransposon in Gli3 gene in the Pdn mouse has been reported. Thus, the responsible gene for Pdn/Pdn is thought to be Gli3 , but the site of mutation within the gene has not been demarcated.
In the present study, we demonstrated that 5442 bp of early retrotransposon was inserted into intron 3 of Gli3 gene in the Pdn mouse (Gli3Pdn). This transposon had almost the same sequence as MMY17106 (EMBL). It had 317-bp long terminal repeat at both ends followed by the identical 6-bp target duplication sequence, GAGACT. Forward and reverse PCR primers were constructed in intron 3 near the insertion point, and a forward primer in the transposon was also constructed. These primers allowed us to discriminate +/+, Pdn /+ and Pdn/Pdn embryos by the PCR products. Morphological determination of the genotypes in the Pdn mouse embryos is impossible before day 12 of gestation. Quick discrimination method of genotypes developed in the present study allows us to investigate the early dysmorphogenetic mechanisms in the brain and limbs in the Pdn/Pdn embryos. Then, the dysmorphogenetic mechanisms in the Pdn/Pdn may be extrapolated to those in GCPS.  相似文献   
84.
Physical and psychological evaluation have been required for TMD patients whose problems are multi dimensional. The questionnaire named the "TMJ Scale" was created to differentiate subjective TMD symptoms of patients. The purpose of this study was to clarify the reliability of the TMJ Scale for Japanese orthodontic patients with TMD and to differentiate the symptoms. Fifty orthodontic patients (average age 21y4m) with a chief complaint of TMD symptoms were compared with thirty patients (average age 21y1m) without TMD symptoms. The results were as follows: female patients in the symptom group in particular showed a higher degree of stress due to the chronic pain and abnormalities than those in the non-symptom group. Significant differences were observed in Pain Report, Joint Dysfunction and Global Scale at the 0.1% significant level, in Non-TM Disorder, Psychological Factor and Chronicity at the 1% level, and in Palpation Pain and Perceived Malocclusion at the 5% level in females. Few psychological problems were observed in male patients in the symptom group. Significant differences were observed in Range of Motion limitation at the 5% level in males. The differences in the psychological factors between male and female patients were clarified by using the TMJ Scale. These findings suggested that it was useful to differentiate the multiple symptoms, especially the psychological factors, by using the TMJ Scale for orthodontic patients with TMD.  相似文献   
85.
This study examined interactive processes that occurred in video-mediated referential communication task. Pairs of participants were assigned to one of four conditions; in a room with partition, or in separate rooms linked by telephone with three levels of noise interference (none, low, and high). In all conditions, a video-monitor link allowed the participants to see the upper body of their partner. Analyses of gestural and visual interaction revealed that participants in partition and no-interference conditions did not rely on the visual channel, while those in the others frequently looked at the monitor. Furthermore, gestural references appeared especially in high-noise condition. Qualitative analyses of conversations showed that participants in high-noise condition relied more on demonstrative references, and used more metaphoric expressions of a whole referent, based on the common ground shared by the pair. These results are discussed in terms of how people collaboratively interact and construct a shared context for communication between them.  相似文献   
86.
OBJECTIVE: To investigate the impact of health-related demographic and socioeconomic factors, as well as the impact of factors associated to social activity and the subjective health evaluation on the functional status of elderly people. METHODS: A cross-sectional multicentric study was conducted in a representative population sample in the city of S?o Paulo, Brazil, in 1989. Functional status was evaluated using a scale of activities of personal and instrumental daily living. It was studied as a dichotomous variable: absence of dependency - disability/difficulty in none of the activities in contrast with moderate/severe dependency - disability/difficulty in 4 or more activities. Multiple regression analysis was applied to hierarchically clustered factors. RESULTS: Those with the following features were more associated to moderate/severe dependency: illiterate, retired, pensioner, house keeper, living in a rented home, age over 65 years, multigenerational family composition, hospitalization in the last 6 months, mental health screening case, no visiting friends, and having a pessimistic perception of his/her own health when compared to their peers. CONCLUSIONS: The identified features associated to moderate/severe dependency suggest a complex net of causes for the declining functional status. However, one can assume that preventive measures directed to specific factors can benefit these population by improving their well-being.  相似文献   
87.
BACKGROUND: Gut ischemia/reperfusion (I/R) frequently occurs in clinical settings as a result of disproportionate splanchnic hypoperfusion during shock. Glutamine (GLN) supplementation of total parenteral nutrition (TPN) before gut I/R improves survival after gut I/R compared with standard TPN. However, it is unknown whether GLN treatment after the occurrence of the insult is beneficial or not. The aims of this study were to examine effects of GLN infusion during gut ischemia on survival, myeloid cell (neutrophils + monocytes) activation, and vascular permeability in organs. METHODS: Male Institute of Cancer Research (ICR) mice were randomized to control and GLN groups. After IV cannulation, mice underwent 90 (experiments 1 and 2) or 60 (experiment 3) minutes of gut I/R. Control mice received normal saline infusion at 1 mL/h for 60 minutes during ischemia, whereas the GLN group was given 3% GLN solution. In experiment 1, survival rates were monitored for 72 hours (n = 25). In experiment 2, peripheral blood was obtained at 2 or 4 hours after reperfusion (n = 17). Reactive oxygen intermediate (ROI) production by myeloid cells was determined by flow cytometry using dihydrorhodamine 123 with or without phorbol myristate acetate stimulation. Expression of CD11a and CD11b on myeloid cells was also measured. Myeloperoxidase (MPO) activity in the lung was evaluated. In experiment 3, vascular permeability in organs was measured using Evans blue at 2 or 4 hours. RESULTS: In experiment 1, survival time in the GLN group was significantly reduced compared with the control group (p = .02, log-rank test). The survival rates were 92% (12/13) and 42% (5/12) for the control and GLN groups at 12 hours (p = .01) and 38% (5/13) and 0% (0/12) at 48 hours (p = .02), respectively. In experiment 2, ROI production was significantly higher in the GLN group than in the control group after PMA stimulation both at 2 and 4 hours. CD11b expression was significantly higher in the GLN group than in the control group at 4 hours. There was no difference in pulmonary MPO activity at either time point. In experiment 3, GLN infusion significantly increased hepatic vascular permeability compared with saline infusion at 4 hours. CONCLUSIONS: GLN infusion during ischemia is detrimental for survival after gut I/R. A possible mechanism is excessive priming of myeloid cells caused by GLN infusion. Timing of GLN administration is critical for outcome after gut ischemic insult.  相似文献   
88.
Diseases, details of interventions, medical cares provided and the condition of use and services of local medical institutions were investigated in the home care support activities during the period from November 1997 to March 2003. We intervened in 1,309 patients. 70% of them were terminal patients with malignant tumor. Interventions were mostly consultations about the life under medical care, guidance about HPN/tube feeding, consultations about nursing and coordination with local medical institutions. 422 of them were under care of family doctors. 502 of them used visiting nursing. 70% of the patients under care of the hospital required high-tech home care and home hospice care. The 5-year activities indicate that nurses who support home care at the hospitals providing acute medical care are expected to 1. serve as the consultation contact for patients and families, 2. support the life under medical care in consultation with internal and external related professionals, 3. use social resources, 4. serve as the contact for providing the logistic support under an emergent situation or under the lack of care-giving capabilities, 5. provide guidance for the safe use of high-tech home medical care by patients/families at the discharge, 6. communicate or coordinate with local medical institutions for continued care/nursing and 7. develop/support the flexible and convenient distribution system of medical equipment and medical materials/drugs or the 24-hour healthcare support system jointly with private enterprises.  相似文献   
89.
We assessed the effect of shift work on the onset of hypertension. The design of this study was that of a cohort study from 1991-2001. In sum, 5338 workers comprised this cohort. The event was the onset of hypertension (systolic blood pressure >or=140 mm Hg and/or diastolic blood pressure >or=90 mm Hg and/or medication). Pooled logistic regression analysis was performed, including job schedule type, age, body mass index, lifestyle, and the results of blood chemistries as covariates. The odds ratio of the onset of hypertension in shift workers for daytime workers was 1.10 and significant. Our study revealed that shift work independently affected the onset of hypertension, and suggested that shift work is a risk factor for the onset of hypertension.  相似文献   
90.
We evaluated error prevention education by clarifying the association between dispensing error factors and behavioral characteristics of pharmacists. The subjects were 98 pharmacists (27 men and 71 women) with a mean age of 29.7 years who gave informed consent for participation in our survey. Between November 2001 and January 2002, a questionnaire survey on dispensing errors was performed using the "Tokyo University Egogram, New Version" for the assessment of behavioral characteristics and the "Safety Behavior Questionnaire" for the assessment of error factors. An association was observed between the incidence of dispensing errors and behavioral characteristics. There was also an association between error contents and behavioral characteristics as well as error factors. With more experience, errors associated with becoming accustomed increased, suggesting that error prevention education is necessary not only for newly qualified pharmacists but also for managers.  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