全文获取类型
收费全文 | 8485篇 |
免费 | 818篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 48篇 |
儿科学 | 215篇 |
妇产科学 | 145篇 |
基础医学 | 1212篇 |
口腔科学 | 227篇 |
临床医学 | 1116篇 |
内科学 | 2093篇 |
皮肤病学 | 172篇 |
神经病学 | 976篇 |
特种医学 | 276篇 |
外科学 | 761篇 |
综合类 | 214篇 |
一般理论 | 2篇 |
预防医学 | 783篇 |
眼科学 | 189篇 |
药学 | 481篇 |
中国医学 | 3篇 |
肿瘤学 | 412篇 |
出版年
2021年 | 122篇 |
2020年 | 92篇 |
2019年 | 140篇 |
2018年 | 163篇 |
2017年 | 104篇 |
2016年 | 99篇 |
2015年 | 131篇 |
2014年 | 215篇 |
2013年 | 262篇 |
2012年 | 407篇 |
2011年 | 380篇 |
2010年 | 211篇 |
2009年 | 202篇 |
2008年 | 313篇 |
2007年 | 369篇 |
2006年 | 339篇 |
2005年 | 348篇 |
2004年 | 322篇 |
2003年 | 278篇 |
2002年 | 330篇 |
2001年 | 308篇 |
2000年 | 274篇 |
1999年 | 253篇 |
1998年 | 141篇 |
1997年 | 111篇 |
1996年 | 112篇 |
1995年 | 105篇 |
1994年 | 79篇 |
1993年 | 78篇 |
1992年 | 202篇 |
1991年 | 182篇 |
1990年 | 192篇 |
1989年 | 175篇 |
1988年 | 187篇 |
1987年 | 206篇 |
1986年 | 185篇 |
1985年 | 161篇 |
1984年 | 125篇 |
1983年 | 90篇 |
1982年 | 59篇 |
1981年 | 61篇 |
1980年 | 62篇 |
1979年 | 93篇 |
1978年 | 89篇 |
1977年 | 73篇 |
1976年 | 57篇 |
1975年 | 64篇 |
1974年 | 76篇 |
1972年 | 56篇 |
1971年 | 60篇 |
排序方式: 共有9325条查询结果,搜索用时 15 毫秒
31.
The postnatal development of alcohol dehydrogenase (ADH) isozymes was studied in liver, kidney, stomach and eye tissues of C57BL/6J inbred male mice using agarose isoelectric focusing and histochemical methods. Development profiles were tissue specific, with adult patterns being attained by 30 days in the liver and stomach, and by 42 days in the kidneys. Ocular ADH-C2 increased in activity at the end of the first week, corresponding to the time of eye opening in the neonate. 相似文献
32.
In vitro study of the transfer of cytokine-inducing substances across selected high-flux hemodialysis membranes. 总被引:2,自引:0,他引:2
The in vitro transfer of cytokine-inducing substances (CIS) across cellulose triacetate and polyacrylonitrile hollow-fiber high-flux hemodialyzers was studied using culture filtrates of gram-negative bacteria isolated from hemodialysis center environments. With Enterobacter cloacae, no transfer of CIS was seen despite the potent cytokine inducibility and endotoxin content of the challenge solution. In contrast, interleukins 1 and 6 and tumor necrosis factor inducing substances did penetrate both dialyzer types challenged with Pseudomonas aeruginosa culture filtrates containing a high endotoxin content. Transfer was not seen, however, upon dilution of the challenge solution to lower, yet clinically very high levels of endotoxin. These results show that, in vitro, the transfer of CIS across high-flux membranes is critically dependent upon the quality and the quantity of the challenge material employed. 相似文献
33.
S Thurber A Chronopoulos C E Stafstrom G L Holmes 《Brain research. Developmental brain research》1992,68(1):35-40
There is controversy as to whether prolonged seizures are more detrimental to the immature than the mature brain. To evaluate this question continuous hippocampal stimulation was used to induce prolonged limbic seizures in 20-, 30- and 60-day-old rats. The long-term effects on learning and activity level were then studied at age 80 days using the Morris water maze, a test of spatial learning and memory, and the open field test, a test of an animal's reaction to a novel environment. Limbic status epilepticus in 60-day-old but not 20- and 30-day-old rats caused long-term impairment of learning in the Morris water maze. No differences were noted between the control and the experimental animals in the open field test. These results suggest that the age of seizure onset is an important determinant of long-term cognitive sequelae. 相似文献
34.
Background : Osseous cranial base tumours in children present as a diverse collection of both benign and malignant pathologies. Concerns raised by the difficulty in accurate diagnosis and local recurrence of benign lesions and by the long-term sequelae of radiotherapy for malignant cranial tumours (marked local growth disturbances, pituitary dysfunction, visual disturbances, late new tumour induction) prompted an evaluation of surgical resection of cranial base tumours in children, with specific regard to safety, efficacy and aesthetic result. Methods : A retrospective review was performed of 10 consecutive children presenting with tumours either arising from or eroding into bone of the cranial base who were managed by surgical resection in a 10-year period from 1986 to 1996. The patients demonstrated a great variation in both presentation and pathology. All underwent surgical resection of tumour with reconstruction where indicated. Results : There were no postoperative complications or mortality. All patients remained clinically free of disease at follow-up, which ranged from 17 months to 9 years (mean 6 years and 4 months). Conclusion : The aggressive surgical resection and craniofacial reconstruction of cranial base tumours in the paediatric population offers a safe and efficacious mode of treatment that obviates problems of diagnosis and local recurrence for benign lesions and of the long-term sequelae of radiotherapy for malignant lesions. 相似文献
35.
Harold O. Goodman Robert Brommage Dean G. Assimos Ross P. Holmes 《World journal of urology》1997,15(3):186-194
An examination of the urinary excretions of 101 normal subjects indicated that the major genetic influence on calcium excretion is a codominant pair of alleles giving rise to three phenotypes, low, intermediate and high (hypercalciuric) excretors. This inference was based on variance, Hardy-Weinberg and segregation analyses. Similar independent gene pairs also appear to influence oxalate and citrate excretion, A 3-locus Hardy-einberg table using estimates of gene frequencies derived from the study of normals suggests that only 3 or 4 leading genes are involved in oxalate stone disease. Strong candidate genes identified from molecular and physiological studies cannot be proposed at present, but it is assumed that they influence the transport of these ions in either the intestine, kidney or both organs. The identification of the genes involved should be facilitated by the reduction of dietary influences on urinary excretions through the use of formula diets. 相似文献
36.
37.
Self-report questionnaires completed by young adults with Type I diabetes were examined to determine if individuals differing in recent metabolic control (Poor, Moderate or Very Good) or disease duration (Long, Short) also vary in either occurrence or type of life events during the past year or occurrence of recent emotional distress. Subjects in Poor control reported more positive and neutral life events during the past year, suggesting even those life changes individuals view benignly may be associated with metabolic control difficulties. Individuals in Poor control also reported more recent symptoms of depression, anxiety and hostility than did individuals in Moderate or Very Good control--symptomatology which may further impair their ability to adhere to a complex self-care regimen. Individuals with Long disease duration reported more positive and negative recent life experiences than did subjects with Short disease duration, but did not evidence concomitant disruptions in metabolic control. The role experience with a chronic disease may play in this finding was unclear, however. Although more research is required to clarify the exact relation of psychosocial variables and diabetic control, these findings suggest that clinically relevant subgroup parameters, subjects' perceptions of life change, and demographic variables may be important factors to assess. 相似文献
38.
39.
Susan Holmes Snydal 《Journal of Midwifery & Women's Health》1988,33(1):4-14
A review of the history of fetal heart rate monitoring is followed by detailed analysis of eight randomized, controlled trials and of a recent prospective study of electronic fetal monitoring compared with intermittent auscultation. No significant differences between the methods were reported in perinatal mortality rates, neonatal infection rates, and Apgar scores. Mixed results were reported for length of labor, maternal analgesic use during labor, maternal genital tract infection rates, umbilical cord pH values, and admissions to neonatal intensive care units. Auscultation was associated in two trials with a significantly increased rate of neonatal seizures. Electronic fetal monitoring was correlated with a significantly increased cesarean delivery rate in the first four trials, and with a significantly increased rate of operative delivery (forceps plus cesarean delivery) in three later trials. A decision tree is presented to assist the clinician in selecting the appropriate fetal monitoring method for a given client. 相似文献
40.
Lung cancer stands as the most important malignant neoplasm in the United States because of its high prevalence, increasing incidence, high rate of mortality, and great potential for prevention through the control of cigarette smoking. The World Health Organization (WHO) classification of lung cancer identifies four major types: squamous cell carcinoma, adenocarcinoma, large cell carcinoma, and small cell carcinoma. These tumors are commonly divided into two groups based on differences in their biology and treatment: small cell (SCLC) and non-small cell carcinomas (NSCLC). This review analyzes NSCLC with a strong emphasis on the practical aspects of treatment. We give recommendations about smoking cessation and early diagnosis through screening of high-risk individuals. We review contemporary diagnostic and staging techniques in the context of the new international TNM system of staging. Subsequent discussions of treatment are based on this new staging system. We stress the pivotal role of surgery for the management of local disease, and in addition present the potential contributions of newer radiation therapy techniques. We examine chemotherapy in detail, including a review of the comparative activity of the available cytotoxic agents against NSCLC, the relative contribution of combination chemotherapy, and the role of surgical adjuvant treatment with either chemotherapy or immunotherapy. We advise that patients with NSCLC be treated under the aegis of modern clinical trials of new therapy whenever possible. When this is not possible, we recommend an individualized approach based on such factors as the patient's age, general state of health, cardiopulmonary status, psychosocial status, and personal system of values. 相似文献