全文获取类型
收费全文 | 1131篇 |
免费 | 68篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 17篇 |
妇产科学 | 23篇 |
基础医学 | 95篇 |
口腔科学 | 22篇 |
临床医学 | 170篇 |
内科学 | 340篇 |
皮肤病学 | 5篇 |
神经病学 | 88篇 |
特种医学 | 7篇 |
外科学 | 91篇 |
综合类 | 42篇 |
预防医学 | 137篇 |
眼科学 | 22篇 |
药学 | 62篇 |
中国医学 | 1篇 |
肿瘤学 | 68篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 11篇 |
2021年 | 27篇 |
2020年 | 9篇 |
2019年 | 25篇 |
2018年 | 30篇 |
2017年 | 22篇 |
2016年 | 22篇 |
2015年 | 33篇 |
2014年 | 33篇 |
2013年 | 64篇 |
2012年 | 75篇 |
2011年 | 80篇 |
2010年 | 43篇 |
2009年 | 46篇 |
2008年 | 70篇 |
2007年 | 65篇 |
2006年 | 82篇 |
2005年 | 69篇 |
2004年 | 90篇 |
2003年 | 88篇 |
2002年 | 89篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有1199条查询结果,搜索用时 15 毫秒
1.
J A Scatina D R Hicks M Kraml M N Cayen 《Xenobiotica; the fate of foreign compounds in biological systems》1989,19(9):991-1002
1. The disposition of AY-30,068 (I), a new tetrahydrocarbazole analgesic drug, was studied in mice, rats, dogs, rhesus monkeys, and man. 2. Oral doses of the 14C-labelled drug in aqueous solution were well absorbed in rodents, but absorption of oral doses of the crystalline drug in dogs was poor. Due to the virtual absence of serum metabolites in rats and dogs, the bioavailability of I was nearly identical to the extent of absorption. Although a small first-pass effect was observed in mice, unchanged I represented a major portion of serum radioactivity. 3. A linear increase in the serum concentrations of I occurred at doses between 0.05 and 25 mg/kg in rats, 0.1 and 50 mg/kg in dogs, and 1-160 mg in man. In rhesus monkeys given a 0.5 mg/kg oral dose, the Cmax and AUC of I were similar to values obtained following a corresponding dose in dogs. 4. After i.v. administration of a 1.0 mg/kg dose the terminal elimination half-life (t1/2 beta) of I was 4 h in mice and 9-10 h in rats and dogs. In rodents, dogs, and several human subjects, the elimination of I was interrupted by secondary peaks. Enterohepatic circulation was confirmed in bile duct cannulated rats, where the t1/2 beta of I was decreased to 2.4 h. In rodents the serum clearance and apparent volume of distribution of I were 0.04-0.2 l/kg.h and 0.5-0.8 l/kg, respectively, and 0.6 l/kg.h and 9.8 l/kg in dogs. 5. In rodents and dogs dosed with 14C-labelled I, radioactivity was excreted almost entirely in the faeces. No unchanged I was detected in rat bile, while about 70% of the radioactivity corresponded to conjugates of parent drug. 相似文献
2.
JoAnn D'Avirro Teresa Dotson Barbara LaPierre Wendy Marshall MaryBeth Mishler Jennifer L. Tanger 《Rehabilitation nursing》1996,21(3):132-138
Restructuring in health care does not have to compromise the pursuit of clinical excellence and quality patient care. The clinical advancement program (CAP) at the Hospital for Special Care is a newly developed multidisciplinary reward and recognition program for clinical staff. The program is integrated into the hospital's structure of service line management and, unlike traditional advancement programs, is open to all levels of care providers: professional personnel, technical staff, and aides. This article describes the basic features of the CAP model and how it was developed by a multidisciplinary task force. 相似文献
3.
JoAnn G. Congdon Ph.D. R.N. Joan K. Magilvy Ph.D. R.N. FAAN 《Public health nursing (Boston, Mass.)》1995,12(1):18-24
Abstract Rural community and public health nursing are characterized by an impressive commitment of nurses to their communities and a connectedness of people to one another. Home care as an integral part of long-term and acute care for the older adult population has emerged as a vital practice area in community health nursing. The purpose of this ethnographic field study was to describe rural home care for frail older adults from the perspective of those providing and receiving care. More than 250 interviews were conducted with home care providers, recipients and their families, and other community members. The setting included eight culturally and geographically diverse counties in rural Colorado. One major theme is presented: the perceived change in the spirit of rural community nursing due to the overwhelming documentation required for home care reimbursement. Oppressive paperwork requirements impeded practice and resulted in fewer home visits per day, low job satisfaction, increased nursing staff turnover, decreased quality of care, and changed the spirit of community nursing from an emphasis on caring and community service to a focus on reimbursement. The study results have timely implications for health policy formulation as the United States undergoes major health care reform. 相似文献
4.
5.
Interaction between a peroxisome proliferator-activated receptor gamma gene polymorphism and dietary fat intake in relation to body mass 总被引:5,自引:0,他引:5
Memisoglu A Hu FB Hankinson SE Manson JE De Vivo I Willett WC Hunter DJ 《Human molecular genetics》2003,12(22):2923-2929
The peroxisome proliferator-activated receptor gamma (PPAR gamma) is a critical regulator of adipogenesis. PPAR gamma+/- mice are resistant to high-fat diet-induced obesity and thus PPAR gamma may mediate physiological responses to dietary fat in other mammals. The aim of this study was to determine whether the human PPAR gamma proline to alanine substitution polymorphism (Pro12Ala) modifies the association between dietary fat and adiposity and plasma lipids. Subjects (n=2141) were controls selected for three case-control studies nested within the Nurses' Health Study, a large ongoing prospective cohort study. Associations between intake of total fat, fat subtypes and BMI were different in PPAR gamma 12Ala variant allele-carriers compared with non-carriers. Among homozygous wild-type Pro/Pro individuals, those in the highest quintile of total fat intake, had significantly higher mean body mass index (BMI) compared with those in the lowest quintile (27.3 versus 25.4 kg/m2, respectively; P-trend<0.0001) whereas among 12Ala variant allele-carriers there was no significant trend observed between dietary fat intake and BMI (P-trend=0.99; P-interaction=0.003). In contrast, intake of monounsaturated fat was not associated with BMI among homozygous wild-type women but was inversely associated with BMI among 12Ala variant allele-carriers (mean in lowest quintile=27.6 versus mean in highest quintile=25.5 kg/m2; P-trend=0.006; P-interaction=0.003). The relationship between dietary fat intake and plasma lipid concentrations also differed according to PPAR gamma genotype. These data suggest that PPAR gamma genotype is an important factor in physiological responses to dietary fat in humans. 相似文献
6.
7.
8.
A prospective study of oral contraceptive use and risk of breast cancer (Nurses' Health Study, United States) 总被引:3,自引:0,他引:3
Susan E. Hankinson Graham A. Colditz JoAnn E. Manson Walter C. Willett David J. Hunter Meir J. Stampfer Frank E. Speizer 《Cancer causes & control : CCC》1997,8(1):65-72
Results of previous epidemiologic studies have provided reassurance that there is little, if any, increase in risk of breast cancer with oral contraceptive (OC) use in general. However, in several studies, an increased risk of breast cancer has been observed in two subgroups, young women who used OCs for extended durations and in women who used OCs prior to a first-term pregnancy. We evaluated these relationships using data from the ongoing Nurses' Health Study cohort (United States). We documented 3,383 cases of breast cancer from 1976 to 1992 among 1.6 million person-years of follow-up. We observed no overall relationship between duration of OC use and breast cancer risk, even among women who reported using OCs for 10 or more years (multivariate relative risk [RR]=1.11, 95 percent confidence interval [CI]=0.94-1.32). Among women less than 45 years of age, the multivariate RR for using OCs for 10 or more years was 1.07 (CI=0.70-1.65) compared with never-users. The risk associated with five or more years of OC use prior to a first full-term pregnancy compared with never-use was 0.96 (CI=0.65-1.43). Among women less than 45 years of age, we observed no evidence of an increased risk with OC use before a first full-term pregnancy (use for five or more years: RR=0.57, CI=0.24-1.31). Because of the age distribution of our cohort, we were unable to evaluate these relationships among women less than 40 years of age. Our study provides considerable evidence that long-term past OC use, either overall or prior to a first full-term pregnancy, does not result in any appreciable increase in breast cancer risk in women over 40 years of age. 相似文献
9.
R. Austin Hicklin Linda Eisenhart Nicole Richetelli Meredith D. Miller Peter Belcastro Ted M. Burkes Connie L. Parks Michael A. Smith JoAnn Buscaglia Eugene M. Peters Rebecca Schwartz Perlman Jocelyn V. Abonamah Brian A. Eckenrode 《Proceedings of the National Academy of Sciences of the United States of America》2022,119(32)
Forensic handwriting examination involves the comparison of writing samples by forensic document examiners (FDEs) to determine whether or not they were written by the same person. Here we report the results of a large-scale study conducted to assess the accuracy and reliability of handwriting comparison conclusions. Eighty-six practicing FDEs each conducted up to 100 handwriting comparisons, resulting in 7,196 conclusions on 180 distinct comparison sets, using a five-level conclusion scale. Erroneous “written by” conclusions (false positives) were reached in 3.1% of the nonmated comparisons, while 1.1% of the mated comparisons yielded erroneous “not written by” conclusions (false negatives). False positive rates were markedly higher for nonmated samples written by twins (8.7%) compared to nontwins (2.5%). Notable associations between training and performance were observed: FDEs with less than 2 y of formal training generally had higher error rates, but they also had higher true positive and true negative rates because they tended to provide more definitive conclusions; FDEs with at least 2 y of formal training were less likely to make definitive conclusions, but those definitive conclusions they made were more likely to be correct (higher positive predictive and negative predictive values). We did not observe any association between writing style (cursive vs. printing) and rates of errors or incorrect conclusions. This report also provides details on the repeatability and reproducibility of conclusions, and reports how conclusions are affected by the quantity of writing and the similarity of content.Forensic science is under scrutiny, particularly for pattern-based disciplines in which source conclusions are reported. The National Research Council report Strengthening Forensic Science in the United States: A Path Forward (1) stated that “The scientific basis for handwriting comparisons needs to be strengthened” and noted that “there has been only limited research to quantify the reliability and replicability of the practices used by trained document examiners.” The President’s Council of Advisors on Science and Technology (PCAST) report Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods (2) expressed concerns regarding the validity and reliability of conclusions made by forensic examiners, and called for empirical testing: “The only way to establish the scientific validity and degree of reliability of a subjective forensic feature-comparison method—that is, one involving significant human judgment—is to test it empirically by seeing how often examiners actually get the right answer. Such an empirical test of a subjective forensic feature-comparison method is referred to as a ‘black-box test.’” The National Commission on Forensic Science also called for such testing (3). Although the accuracy and reliability of conclusions made by forensic document examiners (FDEs) have been the focus of multiple studies over the years (4–10), the designs of those studies are notably different from this study (and from PCAST’s recommendations), and therefore the resulting rates are not directly comparable (in particular, when comparing open-set to closed-set studies, comparing studies based on one-to-one vs. one-to-many examinations, and comparing studies that use notably different conclusion scales; see SI Appendix, Appendix B for a summary).This study was conducted to provide data that can be used to assess the scientific validity of handwriting comparisons, for use by policy makers, laboratory managers, the legal community, and FDEs. This study follows the approach used in the previous FBI Laboratory–Noblis latent print black box study (11) and later recommended by the PCAST report. The design utilizes open-set, one-to-one document comparisons to evaluate the conclusions reached by practicing FDEs when comparing writing samples selected to be broadly comparable to casework. The primary purposes of the study are to measure the accuracy of conclusions by FDEs when comparing handwriting samples and to assess reliability by measuring the reproducibility (interexaminer variability) and repeatability (intraexaminer variability) of those conclusions. Secondary purposes include reporting any associations between the accuracy of the decisions in this study, factors related to the participants (such as training or experience), and factors related to the samples (such as quantity of writing, comparability of content, limitations, or style of writing). 相似文献
10.