全文获取类型
收费全文 | 8940篇 |
免费 | 671篇 |
国内免费 | 74篇 |
专业分类
耳鼻咽喉 | 48篇 |
儿科学 | 305篇 |
妇产科学 | 195篇 |
基础医学 | 1316篇 |
口腔科学 | 344篇 |
临床医学 | 766篇 |
内科学 | 2284篇 |
皮肤病学 | 256篇 |
神经病学 | 691篇 |
特种医学 | 329篇 |
外国民族医学 | 4篇 |
外科学 | 1169篇 |
综合类 | 45篇 |
一般理论 | 2篇 |
预防医学 | 841篇 |
眼科学 | 138篇 |
药学 | 451篇 |
1篇 | |
中国医学 | 59篇 |
肿瘤学 | 441篇 |
出版年
2023年 | 60篇 |
2022年 | 117篇 |
2021年 | 276篇 |
2020年 | 158篇 |
2019年 | 254篇 |
2018年 | 333篇 |
2017年 | 209篇 |
2016年 | 224篇 |
2015年 | 215篇 |
2014年 | 293篇 |
2013年 | 414篇 |
2012年 | 508篇 |
2011年 | 597篇 |
2010年 | 352篇 |
2009年 | 292篇 |
2008年 | 435篇 |
2007年 | 476篇 |
2006年 | 458篇 |
2005年 | 379篇 |
2004年 | 348篇 |
2003年 | 354篇 |
2002年 | 305篇 |
2001年 | 254篇 |
2000年 | 288篇 |
1999年 | 251篇 |
1998年 | 112篇 |
1997年 | 101篇 |
1996年 | 105篇 |
1995年 | 90篇 |
1994年 | 69篇 |
1993年 | 70篇 |
1992年 | 129篇 |
1991年 | 137篇 |
1990年 | 122篇 |
1989年 | 88篇 |
1988年 | 95篇 |
1987年 | 74篇 |
1986年 | 80篇 |
1985年 | 82篇 |
1984年 | 53篇 |
1983年 | 43篇 |
1982年 | 33篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1978年 | 27篇 |
1973年 | 24篇 |
1972年 | 23篇 |
1971年 | 23篇 |
1970年 | 26篇 |
1967年 | 20篇 |
排序方式: 共有9685条查询结果,搜索用时 15 毫秒
41.
Lorenzo Alonso Carrión Francisco Jesús González Sánchez Emilio Alba Conejo Esperanza Torres Sánchez 《Clinical & translational oncology》2004,6(8):462-467
Advanced stage ovarian cancer has a high rate of recurrence even after surgery followed by chemotherapy combining carboplatin
and a taxane. New strategies are currently under way to combat this situation and one of the most promising ones is based
on the knowledge that angiogenesis, the mechanism of formation of new blood vessels coupled with the degradation of the extracellular
matrix for metalloproteinases, could be crucial in the development of this tumor. The principal molecule implicated in angiogenesis
process of ovarian cancer is the vascular endothelial growth factor (VEGF). Several studies are now in progress to clarify
its role as a diagnostic tool or its therapeutic implication. Presently, there is no indication for the use of VEGF in a preliminary
diagnosis seeing that an increase in levels can be seen in both benign and malignant ovarian conditions. VEGF is also responsible
for an increase in vascular permeability and is directly related to symptoms such as ascites and pleural effusion, both of
which are frequent in ovarian cancer. Several papers have analised the role of VEGF as a prognostic factor and some of them
do confirm VEGF as an independent prognostic factor in ovarian cancer. VEGF and the metalloproteinase system coupled with
angiogenesis are currently being evaluated as therapeutic targets but no positive results have yet to be seen in this field.
相似文献
42.
Feliciano García-Vicente Angel Mi?ambres Inmaculada Jerez Ignaci Modolell Leopoldo Pérez Juan Jose Torres 《Radiotherapy and oncology》2003,67(2):239-249
BACKGROUND AND PURPOSE: Modern conformal radiotherapy treatments require accurate dose calculation in any relevant clinical situation. One of these situations is the treatment of lung tumors, where irradiation has to be planned under challenging conditions for dose calculation. In this study we assess the errors in dose values predicted by fast Fourier transform convolution (FFTC) and multigrid superposition (MGS) algorithms implemented in a commercial treatment planning system (TPS). MATERIALS AND METHODS: FFTC and MGS algorithms were used in a FOCUS 3.0.0 (Computerized Medical Systems, USA) to calculate doses in treatment plans using photon beams of 6 and 25 MV nominal energy from a Saturne 43 linac (GE Medical Systems, USA). A 10x10-cm beam irradiating a mediastinum-lung and a thoracic wall-lung-thoracic wall modeled geometry was assessed. The calculated data were compared with measurements performed with radiographic films and ionization chamber. RESULTS: FFTC algorithm leads to an average deviation from ionometric dose measurements of over 10%. Discrepancies between measured and calculated beam fringe values (distance between 50 and 90% isodose lines) of up to 8 mm were observed. For MGS algorithm, all the points assessed in both geometries fulfilled the 3%-3 mm accuracy criteria and the average deviation of absolute dose was about 1%. A maximum of 3 mm deviation in the beam fringe for any depth was found and was within 2 mm beyond the buildup region. Deviations between ionometric and film measurements were within 3%. CONCLUSIONS: MGS algorithm assesses with reasonable accuracy dose distributions and absolute dose in inhomogeneous regions like the lung region. Therefore, and respecting the inhomogeneity dose calculation, the system could be used in routine clinical practice and in dose-escalation programs. This is not true in the case of FFTC algorithm which leads to errors greater than 10% in the absolute dose calculation and underestimates the beam fringe by up to 8 mm. 相似文献
43.
FJ Cowan JT Warner LM Lowes JP Riberio JW Gregory 《Archives of disease in childhood》1997,77(2):109-114
AIMS: To define outcome measures for auditing the clinical care of children and adolescents with insulin dependent diabetes mellitus (IDDM) and to assess the benefit of appointing a dedicated paediatric trained diabetes specialist nurse (PDSN). METHODS: Retrospective analysis of medical notes and hospital records. Glycaemic control, growth, weight gain, microvascular complications, school absence, and the proportion of children undergoing an annual clinical review and diabetes education session were assessed. The effect of the appointment of a PDSN on the frequency of hospital admission, length of inpatient stay, and outpatient attendance was evaluated. RESULTS: Children with IDDM were of normal height and grew well for three years after diagnosis, but grew suboptimally thereafter. Weight gain was above average every year after diagnosis. Glycaemic control was poor at all ages with only 16% of children having an acceptable glycated haemoglobin. Eighty five per cent of patients underwent a formal annual clinical review, of whom 16% had background retinopathy and 20% microalbuminuria in one or more samples. After appointing the PDSN the median length of hospital stay for newly diagnosed patients decreased from five days to one day, with 10 of 24 children not admitted. None of the latter was admitted during the next year. There was no evidence of the PDSN affecting the frequency of readmission or length of stay of children with established IDDM. Non-attendance at the outpatient clinic was reduced from a median of 19 to 10%. CONCLUSIONS: Outcome measures for evaluating the care of children with IDDM can be defined and evaluated. Specialist nursing support markedly reduces the length of hospital stay of newly diagnosed patients without sacrificing the quality of care. 相似文献
44.
B Carlsson C Ankarberg S Rosberg E Norjavaara K Albertsson-Wikland LM Carlsson 《Archives of disease in childhood》1997,77(5):396-400
OBJECTIVES: The amount of adipose tissue influences pubertal development and fertility in girls. A candidate for mediating this is the hormone leptin, derived from adipocytes. This work was carried out to determine whether the leptin concentration in serum is regulated during pubertal development. SUBJECTS AND METHODS: Serum concentrations of leptin were determined by radioimmunoassay in a sample of 252 healthy children representing all pubertal stages. RESULTS: Serum leptin concentrations correlated directly with age (r = 0.53), body mass index (BMI) (r = 0.71), and weight for height SD score (r = 0.44) in girls and with BMI (r = 0.33) and weight for height SD score in boys (r = 0.36). Leptin concentrations increased with pubertal development in girls, resulting in significantly higher concentrations at pubertal stages 4 and 5 than at the prepubertal stage, whereas there was no change in the boys. CONCLUSIONS: Serum leptin concentrations increased during pubertal development in the girls, but remained constant in the boys. Whether the increase in serum leptin concentrations in girls is of importance for, or a consequence of, pubertal development is still to be determined. 相似文献
45.
46.
Proliferative lesions of oviduct and uterus in CD-1 mice exposed prenatally to tamoxifen 总被引:1,自引:3,他引:1
Tamoxifen (TAM) is widely used as adjuvant breast cancer therapy after
surgery and as a chemopreventive agent in women of child-bearing age.
However, TAM therapy has been shown to result in an increased incidence of
endometrial carcinoma in women. The present study was designed to
investigate the effects of TAM (5 mg/kg and 7.5 mg/kg body wt) given i.g.
to pregnant CD-1 mice (1x/day, days 12 through 18 of gestation) on their
female offspring. Progressive proliferative hyperplasia of the oviduct was
frequently seen in TAM-exposed offspring, reaching 100% incidence by 52
weeks in both treatment groups. These females also developed progressive
proliferative uterine lesions, including moderate/severe cystic endometrial
hyperplasia (34-50%) and polypoid adenomas (27-30%) between 53 and 78
weeks. Deciduomas (15%) occurred at young ages (12 and 24 weeks) while
leiomyomas (14%), a malignant leiomyosarcoma, and ovarian granulosa cell
tumors (14%), were found between 72 and 78 weeks. Our findings thus suggest
a strong association between transplacental TAM and reproductive tract
abnormalities in female CD-1 mice.
相似文献
47.
OBJECTIVE: The ketogenic diet is a high-fat, low-protein, low-carbohydrate diet developed in the 1920s for the treatment of children with difficult to control seizures. Despite advances in both the pharmacotherapy and the surgery of epilepsy, many children continue to have difficult-to-control seizures. This prospective study sought to determine the ketogenic diet's effectiveness and tolerability in children refractory to today's medications. METHODS: One hundred fifty consecutive children, ages 1 to 16 years, virtually all of whom continued to have more than two seizures per week despite adequate therapy with at least two anticonvulsant medications, were prospectively enrolled in this study, treated with the ketogenic diet, and followed for a minimum of 1 year. Seizure frequency was tabulated from patients' daily seizure calendars and seizure reduction calculated as percentage of baseline frequency. Adverse events and reasons for diet discontinuation were recorded. RESULTS: The children (mean age, 5.3 years), averaged 410 seizures per month before the diet, despite an exposure to a mean of 6.2 antiepileptic medications. Three months after diet initiation, 83% of those starting remained on the diet and 34% had >90% decrease in seizures. At 6 months, 71% still remained on the diet and 32% had a >90% decrease in seizures. At 1 year, 55% remained on the diet and 27% had a >90% decrease in seizure frequency. Most of those discontinuing the diet did so because it was either insufficiently effective or too restrictive. Seven percent stopped because of intercurrent illness. CONCLUSIONS: The ketogenic diet should be considered as alternative therapy for children with difficult-to-control seizures. It is more effective than many of the new anticonvulsant medications and is well tolerated by children and families when it is effective. 相似文献
48.
Two girls (a 5 year old and a 21 month old) experiencing mononucleosis syndrome with coincidental human herpesvirus (HHV)-7 and Epstein-Barr virus (EBV) infections are described. One patient had primary HHV-7 infection and reactivated EBV infection. The other had primary HHV-7 and EBV infections. These cases indicated that HHV-7 is capable of inducing infectious mononucleosis-like illness. Multiple herpesvirus infection in one of the patients also suggests that interaction among herpesviruses can occur in vivo. The consequence of this interaction may have clinical implications. 相似文献
49.
Liliana Ala Andrade Renato Z Torres An José Fs Sales Regina Vicentini Gustavo A De Souza 《Pathology oncology research : POR》1998,4(1):44-47
Three cases of intravenous leiomyomatosis (IVL) of the uterus, a rare benign smooth-muscle tumor, are described. A preoperative
diagnosis of IVL was not made in any of the patients, all of which presented with a pelvic mass with the presumptive diagnosis
of leiomyoma. Surgical exploration confirmed the presence of uterine mass and two of the three cases showed extra-uterine
extension into the ovarian or uterine veins. Histological examination demonstrated a fascicular pattern of bland spindle-shaped
smooth-muscle cells, which extended to veins inside the myometrium or to extrauterine veins. This was confirmed by immunohistochemical
stain for desmin and factor VIII. Despite their histological benignity, these lesions have a tendency to metastasize and are
closely related to the conditions called “benign metastasizing leiomyoma” and “intracaval mass and cardiac extension”. The
primary treatment of IVL is hysterectomy and excision of any extrauterine tumor, when technically feasible. Anti-estrogenic
therapy has been suggested as potentially useful in controlling of unresectable tumor. According to the literature, the follow-up
must be long and periodic postoperative ultrasonic or magnetic nuclear resonance imaging studies may be useful in detecting
growth of residual intravascular tumor. 相似文献
50.
A comprehensive review of the natural history of Helicobacter pylori infection in children 总被引:3,自引:0,他引:3
Torres J Pérez-Pérez G Goodman KJ Atherton JC Gold BD Harris PR la Garza AM Guarner J Muñoz O 《Archives of medical research》2000,31(5):431-469
Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life. 相似文献