全文获取类型
收费全文 | 12882篇 |
免费 | 791篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 94篇 |
儿科学 | 347篇 |
妇产科学 | 339篇 |
基础医学 | 1951篇 |
口腔科学 | 211篇 |
临床医学 | 1321篇 |
内科学 | 2976篇 |
皮肤病学 | 181篇 |
神经病学 | 1184篇 |
特种医学 | 362篇 |
外科学 | 1458篇 |
综合类 | 137篇 |
一般理论 | 14篇 |
预防医学 | 1029篇 |
眼科学 | 250篇 |
药学 | 950篇 |
中国医学 | 8篇 |
肿瘤学 | 920篇 |
出版年
2023年 | 81篇 |
2022年 | 129篇 |
2021年 | 259篇 |
2020年 | 197篇 |
2019年 | 259篇 |
2018年 | 266篇 |
2017年 | 199篇 |
2016年 | 196篇 |
2015年 | 318篇 |
2014年 | 392篇 |
2013年 | 619篇 |
2012年 | 970篇 |
2011年 | 1000篇 |
2010年 | 518篇 |
2009年 | 461篇 |
2008年 | 829篇 |
2007年 | 918篇 |
2006年 | 894篇 |
2005年 | 855篇 |
2004年 | 834篇 |
2003年 | 785篇 |
2002年 | 764篇 |
2001年 | 124篇 |
2000年 | 102篇 |
1999年 | 152篇 |
1998年 | 152篇 |
1997年 | 135篇 |
1996年 | 116篇 |
1995年 | 122篇 |
1994年 | 85篇 |
1993年 | 86篇 |
1992年 | 78篇 |
1991年 | 84篇 |
1990年 | 60篇 |
1989年 | 52篇 |
1988年 | 48篇 |
1987年 | 43篇 |
1986年 | 45篇 |
1985年 | 39篇 |
1984年 | 43篇 |
1983年 | 28篇 |
1982年 | 60篇 |
1981年 | 30篇 |
1980年 | 27篇 |
1979年 | 35篇 |
1978年 | 26篇 |
1977年 | 34篇 |
1976年 | 15篇 |
1975年 | 26篇 |
1973年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Michael B. Farnell Gerard V. Aranha Yuji Nimura Fabrizio Michelassi 《Journal of gastrointestinal surgery》2008,12(4):651-656
With improvements in the safety of Whipple resection in recent decades, surgeons have continued to explore the role of more
extensive lymphadenectomy in hope of improving long-term survival. A systematic literature search of level I evidence addressing
the role of the extent of lymphadenectomy was undertaken. Only reports of prospective, randomized controlled trials comparing
pancreaticoduodenectomy with standard lymphadenectomy to pancreaticoduodenectomy with extended lymphadenectomy where information
regarding survival, morbidity, mortality, the number of resected lymph nodes in each group and detailed operative technique
were included. Four prospective, randomized trials comprising some 424 patients and one meta-analysis were identified. In
aggregate, these studies confirmed that the number of resected lymph nodes was significantly higher in the pancreaticoduodenectomy
with extended lymphadenectomy group. Morbidity and mortality rates were comparable. Postoperative diarrhea in the early months
after operation was problematic in patients undergoing extended lymphadenectomy. In none of the studies was a benefit in long-term
survival demonstrated. Standard pancreaticoduodenectomy continues to be the operation of choice for adenocarcinoma of the
head of the pancreas.
Presented at The Society for Surgery of the Alimentary Tract Postgraduate Course “Systematic Reviews of Pancreaticobiliary
Disease Customized for the Gastroenterologist and Gastrointestinal Surgeon” on May 20, 2007, Washington, D.C. 相似文献
32.
J Phy S Foong D Session A Thornhill I Tummon D Dumesic 《Ultrasound in obstetrics & gynecology》2004,23(2):183-187
OBJECTIVES: To characterize ovarian morphology in a group of ovulatory, non-hirsute women with infertility and normal circulating levels of gonadotropins and sex steroids. METHODS: Thirty-three women with normal physical examinations, regular ovulatory menses, and absence of hirsutism (Ferriman-Gallwey score < or = 7) were studied. No woman had thyroid disease, galactorrhea, polycystic ovary syndrome, 21-hydroxylase deficiency or diabetes. Two-dimensional (2D) transvaginal sonography (TVS) was used to measure follicle size and ovarian volume on menstrual cycle day 5. Three-dimensional (3D) TVS images were stored to determine the number of follicles (measuring 2-10 mm in diameter) in the largest sonographic plane. Fasting blood sampling and oral glucose tolerance testing were performed to assess serum gonadotropin and sex steroid levels as well as glucose tolerance. RESULTS: The median ovarian volume by 2D-TVS imaging was 7.2 (range, 2.3-15.8) cm(3) (n = 64 ovaries). No follicles were > 10 mm in diameter. The median number of follicles by 3D-TVS was 4 (range, 2-8) (n = 63 ovaries) in the largest sonographic plane. Fourteen of 63 ovaries (22%) had six or more small follicles in one plane distributed within normal stroma (multifollicular ovary, MFO). No ovary had 10 or more follicles in one plane located within abundant stroma (polycystic ovary). Of 33 women examined, 20 women (61%) had apparently normal ovaries bilaterally, while 13 (39%) had at least one MFO. There were no significant differences between women with and those without MFO in serum gonadotropin and steroid levels or glucose tolerance. CONCLUSIONS: MFO is a common morphological variant in non-hirsute ovulatory women with normal gonadotropin secretion and ovarian steroidogenesis. 相似文献
33.
34.
35.
36.
Gerard A. Riley 《Journal of developmental and physical disabilities》1998,10(2):153-165
The use of stimulus modifications in teaching involves altering the materials of a task in order to simplify its execution. Though their use in teaching stimulus discriminations to people with developmental disabilities has been extensively investigated, less attention has been given to their utilization in teaching response topography. This paper offers some general guidelines about their use for this purpose. In relation to their design, it is suggested that the aim should be to reduce the demands made by task components, to eliminate components, and/or to increase the attentional value of the discriminating features of the response topography. In relation to their application, guidelines are suggested about when they should be employed in conjunction with response prompts; when they should be used, either alone or in conjunction with response prompts, in preference to response prompts alone; whether one or a series of modifications is required; and at what point during teaching should probe trials on the unmodified task be introduced. 相似文献
37.
Insulin like growth factor I is an autocrine regulator of human colon cancer cell differentiation and growth. 总被引:4,自引:0,他引:4
The polyanionic compound suramin triggers enterocyte-like differentiation of the human colic adenocarcinoma cell clone HT29-D4. We now demonstrate that suramin interferes with the binding of IGF-I to its receptor at the surface of HT29-D4 cells. Half-maximum inhibition of 125I-IGF-I binding was obtained in the presence of 25 micrograms/ml suramin. Moreover, the drug was able to dissociate 125I-IGF previously bound to its cell surface receptor. Affinity labeling HT29-D4 cells were cultured in the presence of 10 micrograms/ml of alpha-IR3, a monoclonal antibody directed against the binding site of IGF-I, an inhibition of cell proliferation and a stimulation of cell differentiation was observed. After 10 days of treatment with alpha-IR3, HT29-D4 cells formed a regular monolayer of enterocyte-like cells exhibiting an apical brush border and tight junctions delimiting two domains of the plasma membrane (apical and basolateral). Furthermore, we show that IGF-I significantly increased the initial rate of glucose uptake by HT29-D4 cells, while we have previously shown that suramin decreased glucose consumption. From these data we conclude that IGF-I secreted by the cells themselves, stimulates proliferation of HT29-D4 cells via an autocrine mechanism. Blockade of this stimulation by suramin or by a specific monoclonal antibody inhibits cell growth, glucose uptake and triggers the process of enterocytic differentiation. 相似文献
38.
Georges Dellatolas Lucia Willadino Braga Ligia do Nascimento Souza Gilberto Nunes Filho Elizabeth Queiroz Gerard Deloche 《Journal of the International Neuropsychological Society》2003,9(5):771-782
The effect of the degree of illiteracy (complete or incomplete) on phonological skills, verbal and visual memory and visuospatial skills is examined in 97 normal Brazilian adults who considered themselves illiterate, and 41 Brazilian school children aged 7 to 8 years, either nonreaders or beginning readers. Similar literacy effects were observed in children and in adults. Tasks involving phonological awareness and visual recognition memory of nonsense figures distinguish the best nonreaders and beginning readers. Children performed better than adults at oral repetition of short items and figure recall, and adults better than children at semantic verbal fluency, digit span, and word list recall. A principal component analysis of the correlations between tasks showed that phonological awareness/reading, phonological memory/oral repetition, and semantic verbal memory/fluency tasks, generated different components. The respective role of culturally based preschool activities and literacy on the cognitive functions that are explored in this study is discussed. 相似文献
39.
40.
Objective: To assess how surgery affected the quality of life of patients with acoustic neuromas and to investigate possible predictors of the functional outcome following surgery. Study Design: A questionnaire based on the Glasgow Benefit Inventory was completed by patients randomly selected following acoustic neuroma surgery. Setting: Skull base surgery unit of a university teaching hospital (tertiary referral center). Patients: Fifty-three patients with acoustic tumors (follow-up, 1 to 3 y). Results: With regard to overall quality of life, nine patients (17.4%) reported that it became better, 28 patients (53.8%) worse, and 15 patients (28.8%) that it remained the same. Four patients (7.8%) became better off financially, 15 patients (29.4%) worse, and 32 (62.8%) remained unchanged. Forty-one patients (78.8%) did not change their occupation, and 11 (21.2%) had to change their occupation, mainly because of the adverse effects of the operation. With regard to the age at operation, older patients were found to have better overall quality of life. Moreover, younger patients had worse postoperative financial status and they were more likely to change their occupation after the operation. The tumor size did not significantly affect the overall postoperative quality, but it did affect the postoperative financial status (patients with larger tumors were more likely to have worse postoperative financial status). Conclusion: Acoustic neuroma surgery has a significant impact on patients' overall quality of life. Surgeons proposing to operate on small tumors should not assume that the impact on patients' life will be necessarily less than that following the removal of larger tumors. All patients, especially in the younger age group, should be prepared and thoroughly informed about the consequences of the operation on their quality of life. 相似文献