全文获取类型
收费全文 | 6807篇 |
免费 | 486篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 61篇 |
儿科学 | 167篇 |
妇产科学 | 279篇 |
基础医学 | 771篇 |
口腔科学 | 83篇 |
临床医学 | 1046篇 |
内科学 | 1028篇 |
皮肤病学 | 118篇 |
神经病学 | 504篇 |
特种医学 | 141篇 |
外科学 | 704篇 |
综合类 | 127篇 |
一般理论 | 14篇 |
预防医学 | 1012篇 |
眼科学 | 159篇 |
药学 | 549篇 |
中国医学 | 4篇 |
肿瘤学 | 539篇 |
出版年
2023年 | 27篇 |
2022年 | 58篇 |
2021年 | 128篇 |
2020年 | 62篇 |
2019年 | 136篇 |
2018年 | 151篇 |
2017年 | 113篇 |
2016年 | 146篇 |
2015年 | 154篇 |
2014年 | 206篇 |
2013年 | 322篇 |
2012年 | 459篇 |
2011年 | 488篇 |
2010年 | 303篇 |
2009年 | 256篇 |
2008年 | 451篇 |
2007年 | 419篇 |
2006年 | 417篇 |
2005年 | 378篇 |
2004年 | 371篇 |
2003年 | 335篇 |
2002年 | 319篇 |
2001年 | 116篇 |
2000年 | 105篇 |
1999年 | 104篇 |
1998年 | 58篇 |
1997年 | 57篇 |
1996年 | 57篇 |
1995年 | 61篇 |
1994年 | 27篇 |
1993年 | 48篇 |
1992年 | 59篇 |
1991年 | 62篇 |
1990年 | 51篇 |
1989年 | 43篇 |
1988年 | 35篇 |
1987年 | 37篇 |
1986年 | 34篇 |
1985年 | 38篇 |
1984年 | 49篇 |
1983年 | 65篇 |
1982年 | 57篇 |
1981年 | 54篇 |
1980年 | 60篇 |
1979年 | 41篇 |
1978年 | 37篇 |
1977年 | 28篇 |
1976年 | 25篇 |
1974年 | 27篇 |
1966年 | 22篇 |
排序方式: 共有7306条查询结果,搜索用时 15 毫秒
981.
PURPOSE: Although prostate specific antigen doubling time is widely used to predict outcomes such as time to progression and prostate cancer specific mortality, clinicians may be unaware of the impact of method on prostate specific antigen doubling time calculation. We present a critical review of the literature to assess the diversity of methods used to calculate prostate specific antigen doubling time. We then describe the need for methodological consistency with the literature by showing examples from our clinical experience at our institution. MATERIALS AND METHODS: A comprehensive review of articles evaluating prostate specific antigen doubling time as a prognostic and predictive indicator in various prostate cancer disease states was performed using PubMed. Case examples were drawn from the prostate cancer database at our institution. The database is a registry of 4,651 patients with prostate cancer who have been seen at our institution since 1998. RESULTS: The methodology of prostate specific antigen doubling time calculation is inconsistent in the literature. Based on our experience and data presented in the literature the different methods in the literature are not always interchangeable. Small deviations from the methods outlined in a study can sometimes lead to wide variation in calculated prostate specific antigen doubling time. This variation of up to several months or longer is large enough to cause errors in assessment of prognosis and can even lead to incorrect management. The rules for prostate specific antigen doubling time calculation found in the literature can be categorized into 4 parameter groups, including method, calculation interval, data acquisition rules and data analysis rules. Case examples illustrate the importance of adherence to the literature with regard to each parameter. CONCLUSIONS: Consistency with the literature in methodological elements of prostate specific antigen doubling time calculation is essential for the accurate calculation of prostate specific antigen doubling time. Clinicians and researchers should understand how methodological differences influence the value of calculated prostate specific antigen doubling time for purposes of patient care and research. 相似文献
982.
West CR Curr L Battin MR Harding JE McCowan LM Belgrave S Knight DB Westgate JA 《The Australian & New Zealand journal of obstetrics & gynaecology》2005,45(3):207-210
BACKGROUND: Regional audits of term infants with neonatal encephalopathy (NE) provide an opportunity to examine issues related to causation and quality of care. AIM: To document antenatal and intrapartum antecedents in a contemporary cohort of term infants with moderate or severe neonatal encephalopathy. METHODS: Term infants admitted with moderate-severe neonatal encephalopathy over 4 years were identified. The clinical records were reviewed for information about the pregnancy and birth including interpretation of monitoring and subsequent management of the labour and delivery. RESULTS: Fifty-two maternal records were reviewed. No mothers were diabetic or had gestations > 42 weeks, but 17% of the babies were small for gestational age (SGA). The cohort had evidence of antenatal hypoxia in 15%, a sentinel event in 25% and suboptimal fetal monitoring practice in at least 42% of cases. CONCLUSIONS: Peripartum events were the major contributors to neurological damage in infants with neonatal encephalopathy. Suboptimal fetal monitoring practice and sentinel events remain the most common contributors. Ongoing education and training to address these issues should be available to all involved with intrapartum care in New Zealand. 相似文献
983.
Ghetti C Gregory WT Edwards SR Otto LN Clark AL 《American journal of obstetrics and gynecology》2005,193(1):53-57
OBJECTIVE: This study evaluates the relationship between symptoms of pelvic floor disorders, and measurement of pelvic organ prolapse. STUDY DESIGN: This retrospective cross-sectional study assessed prolapse in 905 women in an academic urogynecologic practice using the Pelvic Organ Prolapse Quantification exam. Symptoms were assessed with a Likert symptom questionnaire and the Urogenital Distress Inventory. Relationships between symptoms and prolapse were analyzed using Spearman's correlation. RESULTS: Symptoms of "bulging" correlated moderately to the greatest extent of prolapse (r=0.4, P<.001). Frequency of bother progressively increases when the leading edge descends from -3 and 0. Between +1 and +5, 90% of women report bother. Symptoms typically attributed to anterior or posterior wall prolapse did not correlate with descent of the respective compartment. CONCLUSION: "Bulging" is the principle symptom that correlates with prolapse severity. We found no discrete anatomic position that discriminates between prolapse as a disease state and normal anatomic variation. 相似文献
984.
985.
Timothy J. Regan Mohammad I. Khan Philip O. Ettinger Bunyad Haider Michael M. Lyons Henry A. Oldewurtel Marilyn Weber 《The Journal of clinical investigation》1974,54(3):740-752
In view of the variables that obscure the pathogenesis of cardiomyopathy, a study was undertaken in mongrel dogs fed ethanol as 36% of calories for up to 22 mo. Both the experimental and control groups maintained body weight, hematocrit, plasma vitamin, and protein levels. Left ventricular function was evaluated in the intact anesthetized dog using indicator dilution for end-diastolic and stroke volume determinations. During increased afterload with angiotensin, the ethanol group exhibited a larger rise of end-diastolic pressure (P<0.01), whereas end-diastolic and stroke volume responses were significantly less than in controls. Preload increments with saline elicited a significantly higher end-diastolic pressure rise in the ethanol group (P<0.01). No hypertrophy, inflammation, or fibrosis was present and it was postulated that the enhanced diastolic stiffness was related to accumulation of Alcian Blue-positive material in the ventricular interstitium.To evaluate myocardial lipid metabolism, [1-(14)C]oleic acid was infused systemically. Plasma specific activity and myocardial lipid uptake were similar in both groups. There was a significantly increased incorporation of label into triglyceride, associated with a reduced (14)CO(2) production, considered the basis for a twofold increment of triglyceride content. In addition, diminished incorporation of [(14)C]oleic acid into phospholipid was observed accompanied by morphologic abnormalities of cardiac cell membranes. Potassium loss and sodium gain, like the lipid alteration, was more prominent in the subendocardium. Thus, chronic ethanol ingestion in this animal model is associated with abnormalities of ventricular function without evident malnutrition, analogous to the preclinical malfunction described in the human alcoholic. 相似文献
986.
987.
988.
989.
Cerebral vascular permeability and cellular infiltration in experimental allergic encephalomyelitis 总被引:8,自引:0,他引:8 下载免费PDF全文
Cerebral vascular permeability was measured in guinea-pigs developing experimental allergic encephalomyelitis (EAE). A sensitive double radio-isotope method was used which allowed the permeability changes to be measured independently of alterations in cerebral blood volume. The onset of the disease was accompanied by a striking increase in vascular permeability, but there was no evidence that this change preceded the entry of inflammatory cells into the brain and cord. Injection of serum from rabbits with EAE into normal guinea-pigs had no measurable effect on the cerebral vessels.
These findings are consistent with the view that EAE is a cell-mediated lesion and provide no support for the suggestion that the initial damage is due to circulating antibody.
相似文献990.
Sevoflurane: a new inhalational anesthetic agent. 总被引:26,自引:0,他引:26
Laboratory screening of a series of halogenated methyl isopropyl ethers revealed sevoflurane (fluoromethyl-1,1,1,3,3,3,-hexafluroro-2-propyl ether) as a potent nonexplosive inhalational anesthetic agent. Sevoflurance, a pleasant-smelling liquid, boils at 58.5 degrees C at 760 torr and has a vapor pressure of 200 torr at 25 degrees C. It is nonflammable in air and has lower flammability limits of 11 vols percent in O2 and 10 vols percent in N2O. Sevoflurane exhibits limited chemical reactivity in vitro; it is subject to slight but measurable hydrolysis, and reacts with soda lime to form traces of related ethers. It provides rapid anesthetic induction and recovery consistent with its low distribution coefficients (blood:gas, 0.6; corn oil:gas, 41.6; olive oil:gas, 53.4). In dogs, anesthetic concentrations of sevoflurane did not produce spontaneous cardiac arrhythmias and did not sensitize the heart to epinephrine. Electroencephalographic patterns were similar to those observed during anesthesia with halothane. In rats, small increases in the urinary excretion of inorganic fluoride ion occurred during the first 24 hours after anesthesia. Subacute studies in dogs and rats, using closed-circle absorption with soda lime, revealed no toxicologically significant changes in animals anesthetized frequently for 2 weeks. Sevoflurane appears to be a unique volatile anesthetic agent worthy of further study. 相似文献