全文获取类型
收费全文 | 20289篇 |
免费 | 2064篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 129篇 |
儿科学 | 674篇 |
妇产科学 | 742篇 |
基础医学 | 2988篇 |
口腔科学 | 535篇 |
临床医学 | 2384篇 |
内科学 | 4022篇 |
皮肤病学 | 302篇 |
神经病学 | 1829篇 |
特种医学 | 617篇 |
外科学 | 2519篇 |
综合类 | 553篇 |
一般理论 | 17篇 |
预防医学 | 2075篇 |
眼科学 | 229篇 |
药学 | 1713篇 |
中国医学 | 32篇 |
肿瘤学 | 1024篇 |
出版年
2021年 | 235篇 |
2020年 | 162篇 |
2019年 | 257篇 |
2018年 | 309篇 |
2017年 | 210篇 |
2016年 | 256篇 |
2015年 | 318篇 |
2014年 | 407篇 |
2013年 | 624篇 |
2012年 | 911篇 |
2011年 | 947篇 |
2010年 | 544篇 |
2009年 | 517篇 |
2008年 | 810篇 |
2007年 | 976篇 |
2006年 | 897篇 |
2005年 | 788篇 |
2004年 | 852篇 |
2003年 | 788篇 |
2002年 | 762篇 |
2001年 | 705篇 |
2000年 | 691篇 |
1999年 | 633篇 |
1998年 | 262篇 |
1997年 | 254篇 |
1996年 | 217篇 |
1995年 | 221篇 |
1994年 | 174篇 |
1993年 | 180篇 |
1992年 | 515篇 |
1991年 | 495篇 |
1990年 | 436篇 |
1989年 | 541篇 |
1988年 | 437篇 |
1987年 | 405篇 |
1986年 | 447篇 |
1985年 | 356篇 |
1984年 | 304篇 |
1983年 | 322篇 |
1982年 | 176篇 |
1981年 | 166篇 |
1979年 | 242篇 |
1978年 | 183篇 |
1977年 | 159篇 |
1976年 | 159篇 |
1974年 | 153篇 |
1973年 | 181篇 |
1972年 | 152篇 |
1971年 | 160篇 |
1970年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
A study was conducted to see which attributes contribute most to financial distress in Catholic hospitals. The 1982 total population of U.S. Catholic hospitals was examined. The reason for financial distress was found to be more related to management attributes than to financial variables. 相似文献
82.
Originally conceived as a technique to assess how well current activities contribute to the attainment of organizational goals, portfolio analysis also can be used as a marketing research tool for considering the relative merits of various diversification options under consideration by institutional decision makers. The authors describe the features of portfolio analysis and its use as a tool in the evaluation of health care diversification options. A case study of a hospital that has employed the method in its corporate planning and marketing efforts illustrates the use of this analysis technique. 相似文献
83.
T.M. Walker 《Postgraduate medical journal》1993,69(818):962-963
84.
L Gourley S W Duffy H P Lee A M Walker N E Day 《European journal of clinical nutrition》1988,42(4):333-343
A survey of 40 Singapore Chinese households was performed, obtaining information on major perishable foods purchased for home consumption in the previous week, extent of home consumption (eating in), household dietary habits and housing type, the last as a measure of affluence. Eating out was very common: nine (23 per cent) households ate less than 50 per cent of meals at home. Excluding these nine households, consumption and habits were compared between more affluent and less affluent households. The more affluent households purchased more red meat/offal (P = 0.001), poultry (P = 0.002), vegetables other than green leafy (P = 0.04), fruit (P = 0.007) and eggs (P = 0.04); they also differed significantly in various dietary habits. Significant differences were also observed between English-speaking and Chinese-speaking households. The results suggest that increasing affluence may have brought about substantial dietary change in Singapore, thus meriting further study of the role of diet in changing disease patterns in Singapore. 相似文献
85.
R. Wilson J. H. McKillop M. MacLean J. J. Walker W. D. Fraser† C. Gray† F. Dryburgh† J. A. Thomson 《Clinical endocrinology》1992,37(4):331-334
OBJECTIVES: There is considerable controversy in the literature as to the cause of hyperemesis gravidarum. The aim of this project was to measure a range of thyroid hormone levels in a group of hyperemetic pregnant women. PATIENTS: The study was carried out in 10 first trimester pregnant women with hyperemesis gravidarum. All had been admitted to hospital due to the severity of their symptoms. Fifty age matched, healthy first trimester pregnant women were used as controls. MEASUREMENTS: Blood samples from the women were analysed for total T3 (TT3), total T4 (TT4), free T4 (FT4), TSH, thyrotrophin receptor antibodies (TRAb), thyroid stimulating antibodies (TSAb) and thyroid microsomal and thyroglobulin antibodies. Human chorionic gonadotrophin (hCG) levels were also measured. RESULTS: While individual patients were found to have some abnormal thyroid function tests the group as a whole showed no consistent pattern of abnormality and did not differ significantly from a group of healthy first trimester pregnant women. hCG levels were also within the normal range in the hyperemetic patients. DISCUSSION: None of the women in this study received any antithyroid medication and their symptoms improved as the pregnancy progressed. These results would suggest that there is no underlying thyroid abnormality in patients with hyperemesis gravidarum. It would appear that neither thyroid hormones, nor hCG contribute to the pathogenesis of the condition. 相似文献
86.
San Gil Turner Mullbacher Walker Djordjevic Eamens & Chin 《Scandinavian journal of immunology》1998,47(3):243-253
As it is not known what changes to leucocyte homeostasis are mandatory for effective adjuvant action, the biological relevance of systemic changes elicited by different vaccine formulations can only be interpreted in the context of the immunological outcomes. We used flow cytometry to quantify the changes in leucocyte subsets induced in mice intradermally immunized with SAMA4 (adjuvant group), outer membrane proteins (OMP) purified from Actinobacillus pleuropneumoniae (OMP antigen group), SAMA4 adjuvanted OMP (OMP vaccine group), or phosphate-buffered saline (PBS: control group). This approach allowed direct comparisons to be made between the effects of antigen, adjuvant or antigen–adjuvant complexes on immune effector cell populations. Antigens complexed with the liposome–iscom hybrid adjuvant, SAMA4, generated strong antibody responses and cytotoxic T-cell activity in animals immunized intradermally, reflecting remobilization and recruitment of specific cell populations. Splenomegaly, due to granulocytosis, monocytosis and megakaryocytosis, was most prominent in the OMP vaccine group. Histological examination of spleen sections confirmed that these changes were due primarily to splenic haematopoiesis. Circulating numbers of granulocytes and monocytes increased significantly (P < 0.05) in the blood of the OMP vaccine group, as did granulocyte numbers in the lungs (P < 0.05). No changes in T- and B-cell numbers were detected by flow cytometry in the spleens, lungs or blood over the 28-day period in any treatment group. Thymocyte numbers (predominantly CD4+CD8+ cells) in the OMP vaccine group fell by 95% within 3 days of immunization. Identical cellular responses were obtained when an innocuous antigen, ovalbumin, was complexed with SAMA4 instead of OMP, thus demonstrating that the adjuvant effects of SAMA4 were due to synergistic interaction between antigen and adjuvant and not due to the presence of toxic components. The association of strong adaptive immune responses with such complex changes in leucocyte homeostasis induced by complexing adjuvant and antigen suggested that the changes were important for effective vaccination and were not purely circumstantial. 相似文献
87.
OBJECTIVE: We have assessed whether in-situ hybridization for prolactin messenger RNA (mRNA) provides additional information for the classification of pituitary macroadenomas associated with hyperprolactinaemia. DESIGN: In-situ hybridization for PRL mRNA was performed on surgical biopsies of pituitary adenomas and the results correlated with serum PRL levels and PRL immunoreactivity. PATIENTS: Twenty-one patients (11 men, 10 women) were included; five had normal serum PRL levels, 11 mild hyperprolactinaemia (less than 3000 mU/l) and five marked hyperprolactinaemia (greater than 3000 mU/l). MEASUREMENTS: Immunocytochemistry for PRL and in-situ hybridization for PRL mRNA were performed on surgical biopsies. RESULTS: Immunoreactivity for PRL was detected in tumours from all patients with serum PRL greater than 3000 mU/l and in one of 11 patients with mild hyperprolactinaemia. Positive signal for PRL mRNA was detected in four of five immunopositive cases studied, in a further two cases with mild hyperprolactinaemia, and in one tumour associated with normal serum PRL level. CONCLUSIONS: In-situ hybridization provides evidence of PRL gene activation in the absence of immunoreactivity for prolactin. This may reflect low levels of hormone storage or defective translation of the mRNA. 相似文献
88.
89.
B Walker 《Environmental health perspectives》1997,105(1):15-16
90.
Although knowledge of functional differentiation and tumour-associated changes of breast carcinomas can be gained by the application of antibodies directed against the milk fat globule membrane, more significant information may be obtained by assessment of the potential of breast carcinomas to modulate their antigenic phenotype. In this study, the extend to which primary tumours can undergo modulation in vitro has been investigated, with consideration of the suitability of organ culture in combination with the immunohistochemical detection of two milk fat globule membrane epitopes, HMFG1 and HMFG2, as methods for detecting this. The preservation of three of the 30 carcinomas assessed, all poorly differentiated, was poor after 3 days of culture. The viability of the other 27 was variable, and was greater in the better differentiated tumours and with the addition of insulin. Expression of the milk fat globule membrane epitopes was generally well maintained. Six of the carcinomas showed a significant change in antigen expression, with this being more frequent in tissues incubated with insulin. Hence, a small group of carcinomas have been identified which appear to have a greater capacity to undergo functional differentiation. Organ culture is considered to be a suitable method for maintaining the tissues in vitro for such evaluation, but the problems encountered in quantifying the immunohistochemical staining, because of antigenic heterogeneity, were such that it is suggested that other approaches be employed. 相似文献