全文获取类型
收费全文 | 61228篇 |
免费 | 4082篇 |
国内免费 | 118篇 |
专业分类
耳鼻咽喉 | 558篇 |
儿科学 | 2575篇 |
妇产科学 | 1681篇 |
基础医学 | 7700篇 |
口腔科学 | 658篇 |
临床医学 | 8945篇 |
内科学 | 10695篇 |
皮肤病学 | 903篇 |
神经病学 | 6328篇 |
特种医学 | 1289篇 |
外国民族医学 | 2篇 |
外科学 | 5091篇 |
综合类 | 727篇 |
一般理论 | 109篇 |
预防医学 | 8423篇 |
眼科学 | 805篇 |
药学 | 3944篇 |
中国医学 | 61篇 |
肿瘤学 | 4934篇 |
出版年
2023年 | 302篇 |
2022年 | 443篇 |
2021年 | 1081篇 |
2020年 | 752篇 |
2019年 | 1119篇 |
2018年 | 1281篇 |
2017年 | 1037篇 |
2016年 | 1125篇 |
2015年 | 1327篇 |
2014年 | 1817篇 |
2013年 | 2890篇 |
2012年 | 4212篇 |
2011年 | 4496篇 |
2010年 | 2509篇 |
2009年 | 2246篇 |
2008年 | 4082篇 |
2007年 | 4350篇 |
2006年 | 4163篇 |
2005年 | 4299篇 |
2004年 | 4100篇 |
2003年 | 3857篇 |
2002年 | 3558篇 |
2001年 | 648篇 |
2000年 | 507篇 |
1999年 | 617篇 |
1998年 | 747篇 |
1997年 | 659篇 |
1996年 | 524篇 |
1995年 | 530篇 |
1994年 | 458篇 |
1993年 | 394篇 |
1992年 | 403篇 |
1991年 | 346篇 |
1990年 | 317篇 |
1989年 | 340篇 |
1988年 | 330篇 |
1987年 | 299篇 |
1986年 | 277篇 |
1985年 | 272篇 |
1984年 | 289篇 |
1983年 | 249篇 |
1982年 | 269篇 |
1981年 | 258篇 |
1980年 | 204篇 |
1979年 | 182篇 |
1978年 | 156篇 |
1977年 | 120篇 |
1976年 | 100篇 |
1974年 | 132篇 |
1973年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Neonatal autopsy findings are valuable additions to the information base for current cases and future perinatal care, so the reported decline in the autopsy rate is disturbing. In order to estimate the prevalence of the neonatal autopsy among a large population of deaths, we surveyed participating institutions of the Study Group for Complications of Perinatal Care. Investigators from 37 neonatal intensive care units, located in 9 children's hospitals, 4 hospitals for women and infants, and 24 full-service pediatric and adult care hospitals, reported their neonatal death and autopsy rates for 1989. The overall neonatal autopsy rate was 51% among 1645 neonatal deaths. The rate was variable, ranging from 22 to 100%. We found the neonatal autopsy rate to be lower than previously reported and not apparently influenced by the type of center or by the type of medical staff at the centers. In order to assess and potentially reverse the current low rate, the influence of neonatal demographic and clinical factors, as well as physician-related factors, must be studied. 相似文献
102.
When administered systemically, glucose attenuates deficits in memory produced by several classes of drugs, including cholinergic antagonists and opiate agonists. Glucose also enhances memory in aged rats, mice, and humans. In addition, glucose ameliorates age-related reductions in paradoxical sleep. Because deficits in paradoxical sleep are most marked in those individual aged rats that also have deficits in memory, treatments which improve one of these functions may similarly improve the other. The present experiments show that glucose attenuates deficits in paradoxical sleep and memory after atropine administration, with similar dose-response curves for both actions. In the first experiment, rats received saline, atropine (1 mg/kg), glucose (100 mg/kg) or combinations of atropine + glucose (10, 100, 250, and 500 mg/kg) 30 min before assessment on a spontaneous alternation task. In the second experiment, 3-h EEGs were assessed for spontaneous daytime sleep in rats administered saline, atropine (1 mg/kg), glucose (100 mg/kg) or combinations of atropine + glucose (10, 100 and 250 mg/kg). In both experiments, glucose significantly attenuated deficits at an optimal dose of 100 mg/kg. A third experiment assessed blood glucose levels after injections of atropine + glucose (100 mg/kg) and determined that blood glucose levels were similar to those produced by other treatments which enhance memory. These results are consistent with the view that paradoxical sleep and at least one test of memory are similarly influenced by atropine and glucose. 相似文献
103.
Leah L. Albers Deborah Anderson Leslie Cragin Susan Moore Daniels Christine Hunter Kay D. Sedler Dusty Teaf 《Journal of Midwifery & Women's Health》1996,41(4):269-276
We conducted an observational cohort study in three nurse-midwifery services to identify patient characteristics and clinical care measures related to perineal trauma at birth. Data were collected on all women who began care with a nurse-midwife in labor, using an adaptation of the Nurse-Midwifery Clinical Data Set (n = 3,049). Study variables included demographics, perineal management techniques and position for birth, and other intrapartum care and events. Univariate and multivariate analyses showed that episiotomy was strongly related to fetal bradycardia, prolonged second stage, ethnic status, and maternal education level. Warm compresses and flexion/counterpressure to slow delivery were protective. Spontaneous lacerations were influenced by these factors as well. The lateral position for birth was protective, and use of oils or lubricants and the lithotomy position increased lacerations. Multisite studies in nurse-midwifery practices may provide an ideal means of determining effective care measures in healthy populations. 相似文献
104.
Pre-clinical Cushing's syndrome: an unexpected frequent cause of poor glycaemic control in obese diabetic patients 总被引:4,自引:0,他引:4
Gil Leibowitz Anat Tsur Susan D. Chayen Mohammad Salameh Itamar Raz Erol Cerasi & David J. Gross 《Clinical endocrinology》1996,44(6):717-722
OBJECTIVE Autonomous cortisol secretion without clinical stigmata of Cushing's syndrome (CS) has been recently recognized and termed pre-clinical or sub-clinical CS. The common assumption is that CS is an extremely rare cause of uncontrolled diabetes; however, the prevalence of this entity has not been studied. We assessed the prevalence of pre-clinical CS among obese patients with uncontrolled diabetes. PATIENTS AND DESIGN (1) In a retrospective analysis, the medical records of 63 patients with endogenous CS were reviewed. (2) In a cross-sectional study, 90 obese patients (BMI >25 kg/m2) followed in a University Hospital and the local Health Fund endocrine and diabetes clinics, with poorly controlled diabetes (glycosylated haemoglobin >9%), underwent an overnight 1 mg dexamethasone suppression. In patients with non-suppressible cortisol levels (>140 nmol/l), Liddle's 2 and 8 mg dexamethasone suppression tests and imaging studies were performed. MEASUREMENTS The prevalence of poorly controlled diabetes, the major presenting symptom of CS, was assessed in the retrospective analysis. The prevalence of ‘true’ CS and the false positive rate in the overnight dexamethasone suppression test were calculated. The endocrine evaluation of the patients with pre-clinical CS and the effects of surgical cure on glycaemic control are described. RESULTS In the retrospective analysis, 11 (17.5%) had diabetes and 2 (3.2%) lacked the classic physical characteristics of the syndrome. In the cross-sectional study, 4 patients failed to suppress plasma cortisol (<140 nmol/l). In one patient the diagnosis of CS was not confirmed by a standard Liddle’s test and was therefore considered false positive. In the other 3, the diagnosis of CS was confirmed (prevalence of 3.3%, 95% confidence interval 1–9%). In all other patients the overnight cortisol suppression test was normal (cortisol level 47.3 ± 2.5 nmol/l (mean ± SEM)). After surgical treatment of CS, glycaemic control was markedly improved in all 5 patients (2 from retrospective and 3 from cross-sectional studies). CONCLUSIONS The prevalence of pre-clinical Cushing's syndrome in obese patients with poorly controlled diabetes appears to be considerably higher than previously believed. The overnight dexamethasone suppression test proved to be a simple, sensitive and highly specific screening test for Cushing's syndrome despite the presence of obesity and hyperglycaemia. 相似文献
105.
A New York court recently struck down state Office of Mental Health regulations governing research involving subjects with impaired decisionmaking capacity. The court held that neither incapacitated adults nor minors could participate in any research protocol that contained a nontherapeutic element, irrespective of possible benefits to the subject or the importance of the knowledge to be gained. Although the decision rested on a technical point of law and dealt only with psychiatric research, the court's holding has significantly broader implications. 相似文献
106.
Susan Pelke RN David Easa MD 《Journal of obstetric, gynecologic, and neonatal nursing : JOGNN / NAACOG》1997,26(3):279-285
The clinical research coordinator plays a crucial role in organizing a site's participation in the expanding arena of multicenter medical and pharmacologic clinical trials. This summary clarifies the role of the clinical research coordinator for inexperienced staff members assuming these responsibilities and outlines planning procedures leading to successful implementation. Emphasis is placed on establishing an interdependent relationship with the principal investigator, careful protocol assessment, team building, and staff feedback. Useful tools such as study manuals and physicians' study orders are described. 相似文献
107.
108.
Methodological considerations in the study of parental occupational exposures and congenital malformations in offspring 总被引:4,自引:0,他引:4
The existence of hazardous substances in the workplace has raised concerns about the potential of these substances for adverse reproductive effects. Identification of associations between parental occupational exposures and congenital malformations in the offspring may provide the opportunity for preventing such exposures and thus reduce the risk of malformations. However, there are many methodological considerations inherent in studying the potential relation between parental occupational exposures and congenital malformations in the offspring. Considerations relating to outcome include methods and timing of ascertaining cases with malformations, diagnostic criteria, and problems in grouping malformations for purposes of analysis. With regard to measuring exposures, issues include methods for obtaining valid estimates of the nature, duration, timing of exposure, and exposure-response relationship. Other methodological issues discussed include selection of appropriate reference groups, sample size, and multiple hypothesis testing. 相似文献
109.
Perry Guaglianone Kenneth Chan Eduardo DelaFlor-Weiss Rosemarie Hanisch Susan Jeffers Desh Sharma Franco Muggia 《Investigational new drugs》1994,12(2):103-110
Summary We have completed a phase I and pharmacology study of liposomally-encapsulated daunorubicin (DaunoXome). Of 32 patients entered, 30 were evaluable. No toxicity was encountered at the initial doseescalation steps from 10 to 60 mg/m2. At 80 mg/m2, two patients manifested grade 2 neutropenia. At least grade 3 neutropenia occurred in all patients receiving 120 mg/m2. Alopecia and subjective intolerance were mild. Cardiotoxicity was not observed except for an episode of arrhythmia in a patient with lung cancer and prior radiation. Only one minor objective response was observed in this population of refractory solid tumors. Pharmacokinetics differed from those of the free drug with no detection of daunorubicinol. We recommend future phase II studies with a dose of 100 mg/m2 in previously treated and 120 mg/m2 of DaunoXome in previously untreated patients with solid tumors.EDW is supported in part by ACS award 92-14-1 相似文献
110.
S. S. Kerwar Susan C. Ridge M. Jane Landes Joseph C. Nolan Arnold L. Oronsky 《Inflammation research》1994,43(3-4):206-210
Rabbit inflamed synovial tissue grown in culture synthesizes a factor that induces collagenase synthesis in chondrocytes and in cartilage. Synthesis of this factor by the synovial tissue is inhibited by cycloheximide but not by indomethacin. The factor has an apparent molecular weight of 30,000, is stable to heat and to trypsin treatment but is inactivated by acid. Induction of collagenase synthesis in chondrocytes occurs after a lag period of 6 hours. 相似文献