全文获取类型
收费全文 | 1126篇 |
免费 | 98篇 |
国内免费 | 61篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 58篇 |
妇产科学 | 22篇 |
基础医学 | 191篇 |
口腔科学 | 32篇 |
临床医学 | 145篇 |
内科学 | 286篇 |
皮肤病学 | 14篇 |
神经病学 | 48篇 |
特种医学 | 90篇 |
外国民族医学 | 12篇 |
外科学 | 164篇 |
综合类 | 20篇 |
预防医学 | 59篇 |
眼科学 | 5篇 |
药学 | 58篇 |
中国医学 | 2篇 |
肿瘤学 | 58篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 5篇 |
2019年 | 18篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 24篇 |
2014年 | 38篇 |
2013年 | 47篇 |
2012年 | 38篇 |
2011年 | 42篇 |
2010年 | 45篇 |
2009年 | 50篇 |
2008年 | 61篇 |
2007年 | 87篇 |
2006年 | 47篇 |
2005年 | 55篇 |
2004年 | 30篇 |
2003年 | 20篇 |
2002年 | 30篇 |
2001年 | 29篇 |
2000年 | 23篇 |
1999年 | 38篇 |
1998年 | 48篇 |
1997年 | 39篇 |
1996年 | 28篇 |
1995年 | 29篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 6篇 |
1989年 | 26篇 |
1988年 | 29篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1976年 | 18篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1970年 | 4篇 |
排序方式: 共有1285条查询结果,搜索用时 15 毫秒
11.
12.
OBJECTIVES: To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection. PATIENTS AND METHODS: Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation). RESULTS: Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease. CONCLUSIONS: During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease. 相似文献
13.
14.
15.
Arianne C Lim Kitty WM Bloemenkamp Kees Boer Johannes J Duvekot Jan Jaap HM Erwich Tom HM Hasaart Pieter Hummel Ben WJ Mol Jos PM Offermans Charlotte M van Oirschot Job G Santema Hubertina CJ Scheepers Willem A Schöls Frank PHA Vandenbussche Maurice GAJ Wouters Hein W Bruinse 《BMC pregnancy and childbirth》2007,7(1):1-6
Background
Adequate vitamin D concentrations during pregnancy are necessary to neonatal calcium homeostasis, bone maturation and mineralization. The aim of study is to evaluate serum vitamin D concentrations in mothers and their newborns and effect of vitamin D deficiency on pregnancy outcomes.Methods
552 pregnant women were recruited from Tehran University educating hospitals in the winter of 2002. Maternal and cord blood samples were taken at delivery. The serum was assayed for 25-hydroxyvitamin D3, calcium, phosphorus and parathyroid hormone.Results
The prevalence of vitamin D deficiency in maternal and cord blood samples were 66.8% and 93.3%, respectively (<35 nmol/l). There was significant correlation between maternal and cord blood serum concentrations of vitamin D. In mothers with vitamin D deficiency, cord blood vitamin D concentrations was lower than those from normal mothers (P = .001). Also, a significant direct correlation was seen between maternal vitamin D intake and weight gain during pregnancy.Conclusion
Consideration to adequate calcium and vitamin D intake during pregnancy is essential. Furthermore, we think it is necessary to reconsider the recommendation for vitamin D supplementation for women during pregnancy. 相似文献16.
Primary tumor cells of myeloma patients induce interleukin-6 secretion in long-term bone marrow cultures 总被引:6,自引:9,他引:6
Lokhorst HM; Lamme T; de Smet M; Klein S; de Weger RA; van Oers R; Bloem AC 《Blood》1994,84(7):2269-2277
Long-term bone marrow cultures (LTBMC) from patients with multiple myeloma (MM) and normal donors were analyzed for immunophenotype and cytokine production. Both LTBMC adherent cells from myeloma and normal donor origin expressed CD10, CD13, the adhesion molecules CD44, CD54, vascular cell adhesion molecule 1, very late antigen 2 (VLA-2), and VLA- 5, and were positive for extracellular matrix components fibronectin, laminin, and collagen types 3 and 4. LTBMC from myeloma patients and normal donors spontaneously secreted interleukin-6 (IL-6). However, levels of IL-6 correlated with the stage of disease; highest levels of IL-6 were found in LTBMC from patients with active myeloma. To identify the origin of IL-6 production, LTBMC from MM patients and normal donors were cocultured with BM-derived myeloma cells and cells from myeloma cell lines. IL-6 was induced by plasma cell lines that adhered to LTBMC such as ARH-77 and RPMI-8226, but not by nonadhering cell lines U266 and FRAVEL. Myeloma cells strongly stimulated IL-6 secretion in cocultures with LTBMC adherent cells from normal donors and myeloma patients. When direct cellular contact between LTBMC and plasma cells was prevented by tissue-culture inserts, no IL-6 production was induced. This implies that intimate cell-cell contact is a prerequisite for IL-6 induction. Binding of purified myeloma cells to LTBMC adherent cells was partly inhibited by monoclonal antibodies against adhesion molecules VLA-4, CD44, and lymphocyte function-associated antigen 1 (LFA-1) present on the plasma cell. Antibodies against VLA-4, CD29, and LFA-1 also inhibited the induced IL-6 secretion in plasma cell-LTBMC cocultures. In situ hybridization studies performed before and after coculture with plasma cells indicated that LTBMC adherent cells produce the IL-6. These results suggest that the high levels of IL-6 found in LTBMC of MM patients with active disease are a reflection of their previous contact with tumor cells in vivo. These results provide a new perspective on tumor growth in MM and emphasize the importance of plasma cell-LTBMC interaction in the pathophysiology of MM. 相似文献
17.
p16INK4A and p15INK4B gene deletions in primary leukemias 总被引:4,自引:0,他引:4
Haidar MA; Cao XB; Manshouri T; Chan LL; Glassman A; Kantarjian HM; Keating MJ; Beran MS; Albitar M 《Blood》1995,86(1):311-315
The 9p21 locus has been deleted at a high frequency in a wide variety of tumors. Recently, two genes, p16INK4A and p15INK4B (also called MTS1 and MTS2), have been localized in close proximity at the 9p21 locus, encoding cyclin-dependent kinases 4/6 inhibitors of relative molecular mass 16 kD and 15 kD, respectively and also found to be deleted at a high frequency in tumor cell lines. We analyzed p16INK4A and p15INK4B genes in 178 cases of primary leukemias including 81 cases of chronic lymphocytic leukemia (CLL), seven of hairy cell leukemia (HCL), seven of chronic myelogenous leukemia (CML), 43 of acute myelogenous leukemia (AML), 27 of acute lymphoblastic leukemia (ALL), and 13 of myelodysplastic syndrome (MDS) by Southern blot analyses. The ALL cases showed a relatively high frequency of homozygous deletions (22%, 6 of 27) at the p16INK4A gene locus. Interestingly, of the six cases with p16INK4A homozygous deletions, only three showed homozygous deletions at the p15INK4B gene. In 81 CLL patients, we detected one homozygous and five heterozygous deletions at both the p16INK4A and p15INK4B genes and two heterozygous deletions at the p16INK4A gene alone. Deletion of these two genes in AML cases is relatively low (9%). We did not detect deletions in any of the MDS, HCL, and CML cases examined. Sequence analyses of p16INK4A gene of six CLL cases with heterozygous deletion at this locus showed a 27-bp deletion at the splice acceptor site of intron 1 in one case and changes in the coding sequence in three other cases. The data presented in this report showed that (1) p16INK4A and p15INK4B genes are preferentially deleted homozygously in ALL and heterozygously in CLL cases with frequent mutation in the second allele, and (2) p16INK4A gene appears to be more frequently deleted than p15INK4B gene. 相似文献
18.
19.
Janneke AL van Kempen Henk J Schers Anne Jacobs Sytse U Zuidema Franca Ruikes Sarah HM Robben René JF Melis Marcel GM Olde Rikkert 《The British journal of general practice》2013,63(608):e225-e231
Background
Primary care is increasingly interested in the identification of frailty, as it selects the target population for integrated care. However, instruments for the identification of frailty specifically validated for use in primary care are scarce. This study developed the Easycare Two-step Older persons Screening (Easycare-TOS), which provides a valid, efficient, and pragmatic screening procedure to identify frail older people.Aim
This paper aims to describe the development of the Easycare-TOS and the data from the pilot studies.Design and setting
Observational pilot study in seven academic GP practices in and around Nijmegen, The Netherlands.Method
The Easycare-TOS was developed in a cyclic process with the input of stakeholders. In every cycle, the requirements were first defined, then translated into a prototype that was tested in a pilot study. The Easycare-TOS makes optimal use of prior knowledge of the GP, and the professionals’ appraisal is decisive in the frailty decision, instead of a cut-off score. Further, it considers aspects of frailty, as well as aspects of the care context of the patient.Results
The pilot data have shown that after step 1, two-thirds of the patients do not need further assessment, because they are judged as not frail, based on prior knowledge of the GP. The overall prevalence of frailty in this pilot study is 24%. Most professionals who participated in the pilot studies considered the time investment acceptable and the method to be of added value.Conclusion
The Easycare-TOS instrument meets the predefined efficiency, flexibility, and acceptability requirements for use as an identification instrument for frailty in primary care. 相似文献20.
TRA Lane HM Moore IJ Franklin AH Davies 《Annals of the Royal College of Surgeons of England》2015,97(2):e18-e20
The endovenous revolution has accelerated the development of new techniques and devices for the treatment of varicose veins. The ClariVein® mechanochemical ablation device offers tumescentless treatment with a rotating ablation tip that can theoretically become stuck in tissue. We present the first report of retrograde stripping of the small saphenous vein without anaesthesia following attempted use of the ClariVein® device, without adverse sequelae. 相似文献