全文获取类型
收费全文 | 1636篇 |
免费 | 213篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 34篇 |
儿科学 | 97篇 |
妇产科学 | 24篇 |
基础医学 | 130篇 |
口腔科学 | 42篇 |
临床医学 | 235篇 |
内科学 | 357篇 |
皮肤病学 | 108篇 |
神经病学 | 62篇 |
特种医学 | 141篇 |
外科学 | 274篇 |
综合类 | 97篇 |
现状与发展 | 30篇 |
预防医学 | 69篇 |
眼科学 | 19篇 |
药学 | 64篇 |
中国医学 | 3篇 |
肿瘤学 | 87篇 |
出版年
2024年 | 15篇 |
2023年 | 181篇 |
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 55篇 |
2019年 | 22篇 |
2018年 | 57篇 |
2017年 | 52篇 |
2016年 | 46篇 |
2015年 | 59篇 |
2014年 | 92篇 |
2013年 | 74篇 |
2012年 | 46篇 |
2011年 | 43篇 |
2010年 | 88篇 |
2009年 | 100篇 |
2008年 | 44篇 |
2007年 | 69篇 |
2006年 | 39篇 |
2005年 | 42篇 |
2004年 | 29篇 |
2003年 | 29篇 |
2002年 | 49篇 |
2001年 | 35篇 |
2000年 | 37篇 |
1999年 | 44篇 |
1998年 | 40篇 |
1997年 | 51篇 |
1996年 | 44篇 |
1995年 | 38篇 |
1994年 | 31篇 |
1993年 | 37篇 |
1992年 | 14篇 |
1991年 | 12篇 |
1990年 | 19篇 |
1989年 | 31篇 |
1988年 | 28篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1985年 | 17篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 13篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1976年 | 14篇 |
1975年 | 10篇 |
1974年 | 3篇 |
排序方式: 共有1873条查询结果,搜索用时 375 毫秒
991.
HF Pabst DW Spady LM Pilarski MM Carson JA Beeler MP Krezolek 《Acta paediatrica (Oslo, Norway : 1992)》1997,86(12):1291-1297
Spontaneous integrin expression on CD4+, CD8+ and CD19+ lymphocytes at 6 months was significantly lower in breastfed than formula-fed infants ( p < 0.05). In another study of 59 formula-fed and 64 breastfed 12-month-old children blast transformation and cytokine production by lymphocytes, and T cell changes were measured before and after measles-mumps-rubella vaccination (MMR). Before vaccination, lymphocytes of breastfed children had lower levels of blast transformation without antigen ( p < 0.001), with tetanus toxoid ( p < 0.02) or Candida ( p < 0.04), and lower interferon-γ production ( p < 0.03). Fourteen days after the live viral vaccination, only the breastfed children had increased production of interferon-γ ( p < 0.02) and increased percentages of CD56+ ( p < 0.022) and CD8+ cells ( p < 0.004). These findings are consistent with a Thl type response by breastfed children, not evident in formula-fed children. Feeding mode has an important long-term immunomodulating effect on infants beyond weaning. 相似文献
992.
Susan E. Furber MPH PhD BSc GradDipApplEpidemiol Edith Weisberg MBBS MM Judy M. Simpson BSc PhD CStat 《The Australian & New Zealand journal of obstetrics & gynaecology》1997,37(1):107-112
Summary: The records of 738 women with low-grade cervical epithelial abnormalities were examined for changes in degree of cervical disease and lesion size, as well as sociodemographic and behavioural factors which influence the development of invasive cancer of the cervix. Survival analysis was used to determine the predictors and rates of progression and regression. The results suggest that about 80% of low-grade epithelial abnormalities of the cervix will not progress within 2 years. The only predictors of progression were a biopsy diagnosis of CIN 1 and die size of the lesion. Predictors of regression were older age, older age at first intercourse, greater parity, fewer sexual partners, and absence of a past history of genital herpes. Although progression rates of low-grade abnormalities of the cervix were very low, CIN 1 lesions were 2.4 times (95% CI: 1.6 to 3.7) more likely to progress than lower-grade lesions and large lesions (>l/2 ectocervix) were 2.0 times (95% CI: 1.2 to 3.3) more likely to progress than small ones (相似文献
993.
Androgen responsive adult human prostatic epithelial cell lines immortalized by human papillomavirus 18 总被引:9,自引:2,他引:9
Prostate cancer and benign tumors of the prostate are the two most common
neoplastic diseases in men in the United States, however, research on their
causes and treatment has been slow because of the difficulty in obtaining
fresh samples of human tissue and a lack of well characterized cell lines
which exhibit growth and differentiation characteristics of normal
prostatic epithelium. Non-neoplastic adult human prostatic epithelial cells
from a white male donor were immortalized with human papillomavirus 18
which resulted in the establishment of the RWPE-1 cell line. Cells from the
RWPE-1 cell line were further transformed by v-Ki-ras to establish the
RWPE-2 cell line. The objectives of this study were to: (1) establish the
prostatic epithelial origin and androgen responsiveness of RWPE-1 and
RWPE-2 cell lines; (2) examine their response to growth factors; and (3)
establish the malignant characteristics of the RWPE-2 cell line.
Immunoperoxidase staining showed that both RWPE-1 and RWPE-2 cells express
cytokeratins 8 and 18, which are characteristic of luminal prostatic
epithelial cells, but they also coexpress basal cell cytokeratins. These
cell lines show growth stimulation and prostate specific antigen (PSA) and
androgen receptor (AR) expression in response to the synthetic androgen
mibolerone, which establishes their prostatic epithelial origin. Both cell
lines also show a dose-dependent growth stimulation by EGF and bFGF and
growth inhibition when exposed to TGF-beta, however, the transformed RWPE-2
cells are less responsive. RWPE-1 cells neither grow in agar nor form
tumors when injected into nude mice with or without Matrigel. However,
RWPE-2 cells form colonies in agar and tumors in nude mice. In the in vitro
invasion assay, RWPE-1 cells are not invasive whereas RWPE-2 cells are
invasive. Nuclear expression of p53 and Rb proteins was heterogeneous but
detectable by immunostaining in both cell lines. The RWPE-1 cells, which
show many normal cell characteristics, and the malignant RWPE-2 cells,
provide useful cell culture models for studies on prostate growth
regulation and carcinogenesis.
相似文献
994.
Acinar differentiation by non-malignant immortalized human prostatic epithelial cells and its loss by malignant cells 总被引:5,自引:1,他引:5
Invasive prostatic carcinomas and prostatic intraepithelial neoplasia (PIN)
are characterized by a loss of normal cell organization, cell polarity, and
cell:cell and cell:basement membrane adhesion. The objective of this study
was to establish in vitro three-dimensional (3- D) cell models which can be
used to investigate mechanisms involved in acinar morphogenesis and
differentiation in normal prostatic epithelium and their abnormalities in
cancer cells. The process of acinar morphogenesis, including structural and
functional differentiation, was investigated by culture on basement
membrane gels (Matrigel). The human papillomavirus 18 immortalized,
non-tumorigenic cell line RWPE-1, the v- Ki-ras transformed, tumorigenic
RWPE-2 cell line derived from RWPE-1 cells (see previous paper pp.
1221-1229) and the human prostatic carcinoma cell line DU-145 were used.
When cultured on Matrigel, RWPE-2 cells remain as single cells or form
small aggregates and DU-145 cells form large amorphous cell aggregates
without any organization or lumen. In contrast, RWPE-1 cells form acini of
polarized epithelium with a distinct lumen, show a distinct laminin
basement membrane, and express alpha6beta1 integrins at their basal end.
Exposure to conditioned medium from NIH 3T3 cultures accelerates glandular
morphogenesis. Parallel cultures maintained as monolayers on plastic remain
as monolayers. In the presence of the synthetic androgen mibolerone, acinar
cells express prostate specific antigen (PSA) as determined by
immunostaining. We conclude that normal prostate cells can undergo acinar
morphogenesis while tumorigenic cells have lost this ability. The 3-D
cultures provide physiologically relevant in vitro models for elucidating
regulation of growth, morphogenesis and differentiation in the normal human
prostate, for defining heterotypic interactions in benign prostatic
hyperplasia and for establishing the basis for the loss of normal cell
organization in early neoplastic lesions such as PIN as well as during
tumor progression in prostate cancer.
相似文献
995.
996.
The communication development in 11 children with Angelman's syndrome is described. The clinical observation that these children appear to have a greater ability with receptive rather than expressive language is investigated and these skills assessed using published communication schedules. In addition the understanding and the use of nonverbal communication such as natural gesture was studied. The data collected highlight the fact that these children have developed very few words and have difficulty in using gestural or sign systems. This has implications for speech and language therapists and the children's remedial programmes. Possible future longitudinal studies are suggested. 相似文献
997.
998.
GT Lealman RW Logan JH Hutchison MM Kerr AM Fulton CA Brown 《Archives of disease in childhood》1976,51(5):377-384
Serial changes in plasma levels of calcium, phosphorus, magnesium, alkaline phosphatase, and total proteins have been investigated in 138 healthy, term Caucasian infants. Blood samples were obtained for each infant from cord blood and on day 1 and day 6. The infants were studied in three groups according to whether they were breast fed, received 'Ostermilk No. 1' or 'Cow and Gate V' formulas. Levels of calcium, phosphorus, magnesium, alkaline phosphatase, and total proteins did not differ between the groups at birth or on day 1. By day 6 calcium levels were higher and phosphorus levels lower in the breast-fed infants compared with either of the artificially-fed groups. Phosphorus levels were lower in the V Formula group compared with the Ostermilk group but the mean calcium levels of these two groups did not differ significantly. However, only 2-8% of the V Formula group developed hypocalcaemia compared with 18-2% of the Ostermilk group. The only infant developing clinical tetany belonged to the group fed Ostermilk. Evidence is also given which suggests that those infants with low calcium levels on day 1 who were fed the high-solute milk tended to show a fall in calcium by day 6. This did not apply to the two other groups. It is concluded that the use of adapted cows' milk preparations for infant feeding should lead to a reduction in the incidence of neonatal tetany. 相似文献
999.
JKA Roberts MM Robertson MR Trimble 《Journal of neurology, neurosurgery, and psychiatry》1982,45(2):131-138
Six patients with hypergraphia and epilepsy are presented and their clinical features compared with other patients reported in the literature. It is suggested that hypergraphia occurs more frequently in patients with right-sided non-dominant temporal lobe lesions, in contrast for example to the schizophreniform presentation of left-sided lesions. Other features of psychopathology possibly associated with non-dominant lesions, including elation, hypereligiosity and déjà vu experiences, are also discussed. 相似文献
1000.