全文获取类型
收费全文 | 723篇 |
免费 | 71篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 32篇 |
妇产科学 | 11篇 |
基础医学 | 108篇 |
口腔科学 | 33篇 |
临床医学 | 75篇 |
内科学 | 152篇 |
皮肤病学 | 9篇 |
神经病学 | 35篇 |
特种医学 | 32篇 |
外科学 | 109篇 |
综合类 | 14篇 |
预防医学 | 95篇 |
眼科学 | 7篇 |
药学 | 32篇 |
肿瘤学 | 43篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 19篇 |
2014年 | 16篇 |
2013年 | 13篇 |
2012年 | 33篇 |
2011年 | 30篇 |
2010年 | 23篇 |
2009年 | 21篇 |
2008年 | 37篇 |
2007年 | 30篇 |
2006年 | 27篇 |
2005年 | 30篇 |
2004年 | 31篇 |
2003年 | 33篇 |
2002年 | 42篇 |
2001年 | 31篇 |
2000年 | 26篇 |
1999年 | 36篇 |
1998年 | 16篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 18篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 26篇 |
1987年 | 21篇 |
1986年 | 15篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1962年 | 3篇 |
排序方式: 共有795条查询结果,搜索用时 15 毫秒
61.
London J Mock C Abantanga FA Quansah RE Boateng KA 《Bulletin of the World Health Organization》2002,80(5):357-364
OBJECTIVE: To develop, in a mortuary setting, a pilot programme for improving the accuracy of records of deaths caused by injury. METHODS: The recording of injury-related deaths was upgraded at the mortuary of the Komfo Anokye Teaching Hospital, Kumasi, Ghana, in 1996 through the creation of a prospectively gathered database. FINDINGS: There was an increase in the number of deaths reported annually as attributable to injury from 72 before 1995 to 633 in 1996-99. Injuries accounted for 8.6% of all deaths recorded in the mortuary and for 12% of deaths in the age range 15-59 years; 80% of deaths caused by injury occurred outside the hospital and thus would not have been indicated in hospital statistics; 88% of injury-related deaths were associated with transport, and 50% of these involved injuries to pedestrians. CONCLUSIONS: Injury was a significant cause of mortality in this urban African setting, especially among adults of working age. The reporting of injury-related deaths in a mortuary was made more complete and accurate by means of simple inexpensive methods. This source of data could make a significant contribution to an injury surveillance system, along with hospital records and police accident reports. 相似文献
62.
Recent clinical studies have provided evidence that marginal biotin deficiency is more common than previously thought. The validity of that conclusion rests on two indicators of biotin status that depend on renal function. Our goal was to develop and assess the usefulness of two additional indicators in detecting marginal biotin status in a rat model, i.e., 1) activity of the biotin-dependent enzyme propionyl-CoA carboxylase in lymphocytes; and 2) urinary excretion of 3-hydroxypropionic acid, an organic acid that reflects decreased activity of propionyl-CoA carboxylase. Marginal-to-moderate biotin deficiency was induced experimentally by an egg-white diet (deficient rats); the biotin-supplemented rats were fed the egg-white diet plus supplemental biotin. Propionyl-CoA carboxylase activity was determined by an optimized H(14)CO(3)(-) incorporation assay. Urinary organic acids were determined by gas chromatography/mass spectrometry. Lymphocyte propionyl-CoA carboxylase activity decreased dramatically and in parallel with hepatic propionyl-CoA carboxylase activity. By d 7, lymphocyte propionyl-CoA carboxylase activity in each rat in the deficient group had decreased to less than the lowest value of any rat on d 0. By two-way ANOVA, the effects of diet (P < 0.0001), time (P < 0.005) and their interaction (P < 0.0001) were all significant. The urinary excretion of 3-hydroxypropionic acid did not differ between the two groups. Lymphocyte propionyl-CoA carboxylase activity is an early and sensitive indicator of marginal biotin deficiency, whereas the urinary excretion of 3-hydroxypropionic acid is not. 相似文献
63.
Nguyen TT McPhee SJ Nguyen T Lam T Mock J 《American journal of preventive medicine》2002,23(3):207-214
BACKGROUND: Compared with white women, Vietnamese women in the United States have a higher rate of cervical cancer and lower Papanicolau (Pap) test utilization. We evaluated factors associated with awareness of the Pap test, intention to obtain it, and its receipt in Vietnamese-American women. METHODS: In 2000, we conducted a telephone survey of Vietnamese-American women aged >or=18 years living in Santa Clara County, California, and Harris County, Texas. We collected data on sociodemographics, healthcare system access and attitudes, as well as Pap test awareness, attitudes, intentions, and practices. RESULTS: Of 1566 subjects, 74% had heard of the Pap test, and 76% had had at least one. Only 42% of those who never had a Pap test had considered obtaining one. There were no significant differences between the two sites. Women aged >or=65 had the lowest rates for all three outcomes. For all women, younger age, being married, having requested a Pap test, physician recommendation, and preferring a female standby if the doctor was male were associated with Pap test intention. Being married, higher level of education, having a female doctor, having a respectful doctor, having requested the test, and physician recommendation were associated with Pap test receipt. CONCLUSION: Vietnamese-American women have low rates of Pap test awareness, intention, and receipt. The patient-doctor interaction is an important determinant. Efforts to increase Pap test utilization in this population need to be directed at encouraging physicians to offer the Pap test and empowering women to ask for the test. 相似文献
64.
Michael G Hudgens Ira M Longini Suphak Vanichseni Dale J Hu Dwip Kitayaporn Philip A Mock M Elizabeth Halloran Glen A Satten Kachit Choopanya Timothy D Mastro 《American journal of epidemiology》2002,155(2):159-168
The Bangkok (Thailand) Metropolitan Administration cohort of injecting drug users (IDUs) consisted of 1,209 IDUs initially seronegative for human immunodeficiency virus (HIV) who were followed from 1995 to 1998 at 15 Administration drug treatment clinics. At enrollment and approximately every 4 months thereafter, participants were assessed for HIV seropositivity. As of December 1998, there were 133 HIV type 1 seroconversions and approximately 2,300 person-years of follow-up. Of the 133 observed seroconversions, specimens from 126 persons were available for subtyping (27 subtype B, 99 subtype E). In this analysis, the authors assessed differences in subtype-specific transmission while controlling for important risk factors. The methodology used accounts for left truncation, interval censoring, and competing risks as well as for time-varying covariates such as each IDU's history of reported frequency of injection and of incarceration. Using plausible epidemiologic assumptions and controlling for behavioral risks, the authors found that a significantly higher transmission probability was associated with subtype E compared with subtype B in this population. Since many epidemiologic, virologic, and host factors can influence HIV transmission, it was difficult to conclude whether these differences in transmission probabilities were due to biologic properties associated with subtype. 相似文献
65.
Using data from the Coronary Artery Surgery Study (CASS) registry, we evaluated the relationship between cholesterol levels measured at enrollment and the following events: all-cause mortality, cardiac death, fatal myocardial infarction (MI), and nonfatal MI. Only patients with a significant coronary artery disease (at least one lesion with stenosis > or = 50%) were considered for this study. Results presented for mortality are for a period of up to 11.5 years and those for MI are for a maximum of 8 years of follow-up. Analyses were performed for each type of event and for each subgroup: women (n = 1861) and men (n = 10,941) under age 65, and women (n = 426) and men (n = 1144) age 65 or older. After adjusting for important covariates, cholesterol level was not associated with cardiac or all-cause mortality. No relationship between cholesterol level and fatal or nonfatal MI could be demonstrated except for men under age 65. However, in this subgroup the risk of MI was highest for those with low or middle cholesterol levels. The data show that in patients with angiographically determined coronary artery disease, cholesterol level is not a statistically significant risk factor for death or MI over the follow-up period in CASS. 相似文献
66.
Comparison of technetium-99m sulfur colloid and in vitro labeled technetium-99m RBCs in the detection of gastrointestinal bleeding 总被引:1,自引:0,他引:1
Twenty-seven paired Tc-99m sulfur colloid (SC) and Tc-99m RBC studies were evaluated for the detection of GI bleeding. The only two positive Tc-99m SC studies had positive early Tc-99m RBC studies as well. There were 15 other positive Tc-99m RBC studies (three during the first hour) and these were associated with normal Tc-99m SC scans. Approximately 70% of the positive Tc-99m RBC studies occurred after 1 hour. Tc-99m RBCs should be the initial test in patients with GI bleeding. 相似文献
67.
Denison J. Kuruvilla John A. Widness Demet Nalbant Robert L. Schmidt Donald M. Mock Peter Veng-Pedersen 《The AAPS journal》2015,17(5):1246-1254
Fetal RBCs are produced during a period of very rapid growth and stimulated erythropoiesis under hypoxic intrauterine conditions. Fetal RBC life span varies with gestational age (GA) and is shorter than that in healthy adults. Due to the special kinetic properties of life span-based survival of human RBCs, a mathematical model-based kinetic analysis of the survival of fetal RBCs shortly after birth provides a unique opportunity to “look backward in time” to evaluate fetal erythropoiesis. This work introduces a novel method that utilizes postnatal in vivo RBC survival data collected within 2 days after birth to study both nonsteady-state (non-SS) in utero RBC production and changing fetal RBC life span over time. The effect of changes in erythropoiesis rate and RBC life span and the effect of multiple postnatal phlebotomies on the RBC survival curves were investigated using model-based simulations. This mathematical model, which considers both changes in the rate of erythropoiesis and RBC life span and which accurately accounts for the confounding effect of multiple phlebotomies, was applied to survival curves for biotin-labeled RBCs from ten anemic very low birth weight preterm infants. The estimated mean fetal RBC production rate scaled by body weight was 1.07 × 107 RBCs/day g, and the mean RBC life span at birth was 52.1 days; these values are consistent with reported values. The in utero RBC life span increased at a rate of 0.51 days per day of gestation. We conclude that the proposed mathematical model and its implementation provide a flexible framework to study in utero non-SS fetal erythropoiesis in newborn infants.KEY WORDS: cord blood RBCs, fetal erythropoiesis, fetal RBC life span, fetal RBC production, red blood cells 相似文献
68.
Gamma-glutamyl transpeptidase (GGT) activity has been shown to increase in preneoplastic cells in various experimental carcinogenesis models and in some human tumors. This pilot study was undertaken to examine its potential use in detection of sites of human oral carcinogenesis. Samples were taken from 16 surgical specimens: 12 resection specimens for squamous carcinomas and 4 benign mucosal lesions. Twelve of the patients were tobacco users. Diffuse GGT activity was found in all tobacco users and heavy cellular activity in all carcinomas. In four of the carcinoma-resection specimens, occasional cells staining heavily for GGT activity were noted in epithelium distant from the tumor itself. These results are discussed in relation to the potential value of GGT activity as a marker from preneoplastic changes in oral epithelium. 相似文献
69.
70.
K E Brock G Berry L A Brinton C Kerr R MacLennan P A Mock R P Shearman 《The Medical journal of Australia》1989,150(3):125-130
Sexual, reproductive and contraceptive risk factors were investigated in a matched community-based case-control study of carcinoma-in-situ of the uterine cervix in Sydney. The risk was related strongly to the number of sexual partners: women who had had seven or more sexual partners in a lifetime had a six-fold increased risk compared with those with one or no partner. Early age at first sexual intercourse was also a risk factor, but this effect was reduced substantially after adjustment for the number of partners, with only a two-fold excess risk persisting for those with first intercourse before the age of 16 years as compared with those whose first sexual intercourse was at the age of 25 years or later. The long-term use of oral contraceptive agents was associated with an elevated risk (relative risk, 2.3 for more than six years of use); this effect was maintained for both oestrogen and progestogen doses. The risk increased with the number of induced abortions that had been undergone (relative risk, 2.2 for two or more abortions), but this effect was not statistically significant. A protective effect was found for women who had had a tubal ligation, for those who practised the rhythm method of birth control, and for women who breastfed. It is possible that these reduced risks may relate to unmeasured variables of life-style. 相似文献