全文获取类型
收费全文 | 2584篇 |
免费 | 227篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 71篇 |
妇产科学 | 58篇 |
基础医学 | 404篇 |
口腔科学 | 29篇 |
临床医学 | 337篇 |
内科学 | 400篇 |
皮肤病学 | 19篇 |
神经病学 | 290篇 |
特种医学 | 169篇 |
外科学 | 400篇 |
综合类 | 138篇 |
一般理论 | 1篇 |
预防医学 | 228篇 |
眼科学 | 18篇 |
药学 | 163篇 |
肿瘤学 | 92篇 |
出版年
2021年 | 27篇 |
2020年 | 27篇 |
2019年 | 41篇 |
2018年 | 34篇 |
2017年 | 26篇 |
2016年 | 29篇 |
2015年 | 28篇 |
2014年 | 43篇 |
2013年 | 76篇 |
2012年 | 115篇 |
2011年 | 100篇 |
2010年 | 97篇 |
2009年 | 84篇 |
2008年 | 126篇 |
2007年 | 119篇 |
2006年 | 123篇 |
2005年 | 114篇 |
2004年 | 116篇 |
2003年 | 100篇 |
2002年 | 93篇 |
2001年 | 67篇 |
2000年 | 70篇 |
1999年 | 48篇 |
1998年 | 39篇 |
1997年 | 33篇 |
1996年 | 41篇 |
1995年 | 41篇 |
1994年 | 27篇 |
1993年 | 31篇 |
1992年 | 55篇 |
1991年 | 32篇 |
1990年 | 53篇 |
1989年 | 65篇 |
1988年 | 51篇 |
1987年 | 43篇 |
1986年 | 65篇 |
1985年 | 62篇 |
1984年 | 48篇 |
1983年 | 36篇 |
1982年 | 18篇 |
1981年 | 19篇 |
1980年 | 21篇 |
1979年 | 42篇 |
1978年 | 20篇 |
1977年 | 22篇 |
1976年 | 28篇 |
1975年 | 25篇 |
1974年 | 22篇 |
1973年 | 21篇 |
1968年 | 19篇 |
排序方式: 共有2820条查询结果,搜索用时 15 毫秒
961.
Background Burnout among nurses is a serious condition that threatens their own health and that of their patients. In current health care settings, nurses are particularly at risk for burnout given the increased patient acuity and the worsening nursing shortage.
Aim This study examined the influence of effort-reward imbalance, a situational variable, and core self-evaluation, a dispositional variable, on nurse managers' burnout levels over a 1-year period.
Methods A predictive longitudinal survey design was used to examine the relationships described in the model. One hundred and thirty-four nurse managers responded to a mail survey at two points in time.
Results As hypothesized, both personal and situational factors influenced nurse manager burnout over a 1-year time frame. Although burnout levels at Time 1 accounted for significant variance in emotional exhaustion levels 1 year later (β = 0.355), nurses' effort-reward imbalance (β = 0.371) and core self-evaluations (β = −0.166) explained significant additional amounts of variance in burnout 1 year later.
Conclusion Both personal and situational factors contribute to nurse manager burnout over time.
Implications for nursing management Managers must consider personal and contextual factors when creating work environments that prevent burnout and foster positive health among nurses at work. 相似文献
Aim This study examined the influence of effort-reward imbalance, a situational variable, and core self-evaluation, a dispositional variable, on nurse managers' burnout levels over a 1-year period.
Methods A predictive longitudinal survey design was used to examine the relationships described in the model. One hundred and thirty-four nurse managers responded to a mail survey at two points in time.
Results As hypothesized, both personal and situational factors influenced nurse manager burnout over a 1-year time frame. Although burnout levels at Time 1 accounted for significant variance in emotional exhaustion levels 1 year later (β = 0.355), nurses' effort-reward imbalance (β = 0.371) and core self-evaluations (β = −0.166) explained significant additional amounts of variance in burnout 1 year later.
Conclusion Both personal and situational factors contribute to nurse manager burnout over time.
Implications for nursing management Managers must consider personal and contextual factors when creating work environments that prevent burnout and foster positive health among nurses at work. 相似文献
962.
LR Petersen ; GA Satten ; R Dodd ; M Busch ; S Kleinman ; A Grindon ; B Lenes 《Transfusion》1994,34(4):283-289
Background : For persons newly infected with the human immunodeficiency virus type 1 (HIV-1), the time from the onset of infectivity to the development of detectable HIV-1 antibody is unknown. Persons who donate blood during this period account for nearly all instances of HIV-1 transmission from HIV-1 antibody-screened blood transfusions. Study Design and Methods : To estimate the window period from infectivity to HIV-1 antibody positivity, 701 HIV-1-seropositive blood donors who made a previous seronegative donation at 40 United States blood centers were studied. The HIV-1 antibody status was determined for at least one recipient of blood from the seronegative donation preceding the seropositive donation made by 182 of the 701 donors. Results : There were 39 seropositive recipients of blood from these 182 donors. Three donors were excluded from further analysis because the seropositive recipients of their blood had other HIV-1 risk factors or had HIV-1 infection before transfusion. The final study population comprised the remaining 179 donors, of whom 36 (20%) transmitted HIV-1 infection to recipients. When the interval between the seropositive donation and the preceding seronegative donation was less than 180 days, 46 percent of the donors transmitted HIV-1. In contrast, when that interval exceeded 540 days, only 2 percent transmitted HIV-1. A mathematical model was developed to explain the relationship between the probability that the previous seronegative donation occurred during the donor's window period of infectiousness, and hence transmitted HIV-1, as a function of both the window period and the duration between the seropositive and previous seronegative donations. This model indicated that the transmission data were most consistent with an average window period of 45 days. Assuming a log-normal window period distribution, it was estimated with 95 percent certainty that at least 90 percent of persons had a window period of less than 141 days. Conclusion : The window period averages 45 days, with few, if any, donors remaining infectious and seronegative for longer than 6 months. 相似文献
963.
Short-term safety and antiretroviral activity of T-1249, a second-generation fusion inhibitor of HIV 总被引:6,自引:0,他引:6
Eron JJ Gulick RM Bartlett JA Merigan T Arduino R Kilby JM Yangco B Diers A Drobnes C DeMasi R Greenberg M Melby T Raskino C Rusnak P Zhang Y Spence R Miralles GD 《The Journal of infectious diseases》2004,189(6):1075-1083
T-1249 is a 39-aa synthetic peptide that inhibits fusion of human immunodeficiency virus (HIV) to the host target cell. A 14-day open-label, phase 1/2 dose-escalation monotherapy study of the safety and antiretroviral activity of T-1249 was performed on 115 HIV-1-infected adults. At baseline, the majority of the patients had advanced HIV disease (baseline median CD4(+) cell count, 57 cells/microL) and had extensive pretreatment (i.e., pre-T-1249) experience with antiretroviral medications (median, 11 antiretroviral drugs). Patients received T-1249 monotherapy by subcutaneous injection, for 14 days, at doses ranging from 6.25 to 192 mg/day. T-1249 was generally well tolerated, and no dose-limiting toxicity was identified. Injection-site reactions were the most commonly reported adverse event (57%). Dose-dependent decreases in plasma HIV-1 RNA load were observed; the median maximum change from baseline across dose groups ranged from -0.29 log(10) copies/mL (95% confidence interval [CI], -0.43 to -0.05 log(10) copies/mL) for the lowest dose to -1.96 log(10) copies/mL (95% CI, -2.02 to -1.37 copies/mL) for the highest dose. These results indicate that T-1249 is a potent new therapeutic agent for HIV-1 infection. 相似文献
964.
Vascular prevention is most cost-effective in high-risk patients, but secondary prevention misses many opportunities. The high-risk strategy-identifying patients with high levels of risk factors-is problematic because traditional risk factors predict only half of vascular events. In multiple regression, traditional risk factors explained only half of carotid atherosclerosis. New strategies are being explored, such as electron-beam computerized tomographic measurement of coronary calcification, to identify high-risk patients. Carotid plaque is a powerful tool for identifying and managing high-risk vascular patients, as it explains twice as much of unexplained vascular risk as coronary calcium by electron beam computerized tomography, and it has significant advantages compared with intimal-medial thickness. After adjustment for risk factors, patients in the highest quartile of baseline plaque area have 3.5 times the risk of stroke, death, or myocardial infarction compared with those in the lowest quartile. Those with regression or stable plaque have half the risk of those with progression after adjustment for the same panel of risk factors. The therapeutic target is plaque regression or stabilization, not just control of traditional risk factors. Trying to treat arteries without measuring plaque is like trying to treat hypertension without measuring the pressure, or hyperlipidemia without measuring the lipids. 相似文献
965.
966.
967.
Acculturation, drinking, and alcohol abuse and dependence among Hispanics in the Texas-Mexico border
Caetano R Ramisetty-Mikler S Wallisch LS McGrath C Spence RT 《Alcoholism, clinical and experimental research》2008,32(2):314-321
Background: Acculturation has been linked to an increased prevalence of alcohol‐related problems. However, most of the research has been conducted with Hispanic populations in metropolitan areas of the United States, none of which is on the U.S.–Mexico border. This study examines the association between acculturation, heavy episodic drinking, and DSM‐IV alcohol abuse and dependence among Hispanics in the Texas–Mexico border. Methods: The study used data from a survey conducted (2002 to 2003) along the Texas–Mexico border and included 472 male and 484 female Hispanic adults from El Paso, the Rio Grande Valley, and colonias. Based on the Acculturation Rating Scale for Mexican Americans‐II scale, respondents were coded into 4 acculturation categories: “very Mexican oriented,”“Mexican bicultural,”“Anglo bicultural,” or “very Anglo/Anglicized.”. Results: Acculturation was related to lower rates of alcohol use disorders among men and a higher frequency of heavy episodic drinking among women. Multivariate analyses indicate that men who report heavy episodic drinking and those who are “very Mexican,”“bicultural Mexican,” or “bicultural Anglo” are more at higher risk for alcohol abuse and/or dependence compared with “very Anglo/Anglicized” men. For women, acculturation level did not predict alcohol disorders. Statistical analyses included testing for bivariate associations and multivariate logistic regression predicting heavy episodic drinking alcohol abuse or dependence. Conclusions: This study suggests that acculturation has different effects on drinking for men and women. This finding needs some attention as literature also indicates that women drink more and may develop more alcohol‐related problems as they acculturate. This increase in women’s drinking is probably because of U.S. society’s more liberal norms governing female drinking. The “bimodal” distribution of risk, in which only men in “very Anglo” group are at a lower risk than the others, may be unique to the Border. The association between acculturation and alcohol use disorders does not appear to be linear and the effect of acculturation is not uniform on individuals’ drinking behavior. 相似文献
968.
Psychologically induced cooling of a specific body part caused by the illusory ownership of an artificial counterpart 总被引:1,自引:0,他引:1
Moseley GL Olthof N Venema A Don S Wijers M Gallace A Spence C 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(35):13169-13173
The sense of body ownership represents a fundamental aspect of our self-awareness, but is disrupted in many neurological, psychiatric, and psychological conditions that are also characterized by disruption of skin temperature regulation, sometimes in a single limb. We hypothesized that skin temperature in a specific limb could be disrupted by psychologically disrupting the sense of ownership of that limb. In six separate experiments, and by using an established protocol to induce the rubber hand illusion, we demonstrate that skin temperature of the real hand decreases when we take ownership of an artificial counterpart. The decrease in skin temperature is limb-specific: it does not occur in the unstimulated hand, nor in the ipsilateral foot. The effect is not evoked by tactile or visual input per se, nor by simultaneous tactile and visual input per se, nor by a shift in attention toward the experimental side or limb. In fact, taking ownership of an artificial hand slows tactile processing of information from the real hand, which is also observed in patients who demonstrate body disownership after stroke. These findings of psychologically induced limb-specific disruption of temperature regulation provide the first evidence that: taking ownership of an artificial body part has consequences for the real body part; that the awareness of our physical self and the physiological regulation of self are closely linked in a top-down manner; and that cognitive processes that disrupt the sense of body ownership may in turn disrupt temperature regulation in numerous states characterized by both. 相似文献
969.
B L Nichols D W Spence C F Hazlewood L Librik J B Sachen G W Clayton 《Metabolism: clinical and experimental》1972,21(3):187-195
A syndrome of heaviness in the legs and loss of power and resiliency when running has been investigated in football players during a conditioning program. A transient but significant loss of static leg strength was documented. No changes in muscle or serum sodium, potassium and magnesium concentrations were found. A significant doubling of the myofibrillar nitrogen fraction was observed during the 2 wk of observation. The loss of strength during rapid hypertrophy of muscle is consistent with earlier reports in experimental animals. The occurrence of alterations in intracellular protein nitrogen concentrations without concomitant changes in muscle electrolyte composition leads us to question the universal applicability of noncollagen nitrogen as a reference unit for the expression of muscle electrolyte composition. 相似文献
970.
Disruption of intestinal barrier homeostasis is an important pathogenic factor in conditions such as irritable bowel syndrome (IBS). Lactobacillus rhamnosus GG (LGG) improves IBS symptoms through unclear mechanisms. Previous studies utilizing colorectal adenocarcinoma cell lines showed that LGG metabolites prevented interferon gamma (IFN-gamma) induced barrier damage but the model employed limited these findings. We aimed to interrogate the protective effects of LGG on epithelial barrier function using human intestinal epithelial cultures (enteroids and colonoids) as a more physiologic model. To investigate how LGG affects epithelial barrier function, we measured FITC-Dextran (FD4) flux across the epithelium as well as tight junction zonula occludens 1 (ZO-1) and occludin (OCLN) expression. Colonoids were incubated with fecal supernatants from IBS patients (IBS-FSN) and healthy controls in the presence or absence of LGG to examine changes in gut permeability. Enteroids incubated with IFN-gamma demonstrated a downregulation of OCLN and ZO-1 expression by 67% and 50%, respectively (p<0.05). This was accompanied by increased paracellular permeability as shown by leakage of FD4. Pretreatment of enteroids with LGG prevented these changes and normalized OCLN and ZO-1 to control levels. These actions were independent of its action against apoptosis. However, these protective effects were not seen with LGG cell wall extracts, LGG DNA, or denatured (boiled) LGG. Intriguingly, IBS-FSN injected into colonoids increased paracellular permeability, which was prevented by LGG. LGG, likely due to secreted proteins, protects against epithelial barrier dysfunction. Bacterial-derived factors to modulate gut barrier function may be a treatment option in disorders such as IBS. 相似文献