全文获取类型
收费全文 | 995篇 |
免费 | 97篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 29篇 |
妇产科学 | 94篇 |
基础医学 | 152篇 |
口腔科学 | 19篇 |
临床医学 | 131篇 |
内科学 | 189篇 |
皮肤病学 | 31篇 |
神经病学 | 23篇 |
特种医学 | 163篇 |
外科学 | 84篇 |
综合类 | 19篇 |
预防医学 | 69篇 |
眼科学 | 5篇 |
药学 | 70篇 |
肿瘤学 | 59篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 20篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 26篇 |
2011年 | 29篇 |
2010年 | 22篇 |
2009年 | 22篇 |
2008年 | 47篇 |
2007年 | 62篇 |
2006年 | 27篇 |
2005年 | 39篇 |
2004年 | 32篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 29篇 |
2000年 | 34篇 |
1999年 | 46篇 |
1998年 | 36篇 |
1997年 | 36篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 23篇 |
1993年 | 26篇 |
1992年 | 32篇 |
1991年 | 30篇 |
1990年 | 38篇 |
1989年 | 30篇 |
1988年 | 26篇 |
1987年 | 20篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 14篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1976年 | 11篇 |
1975年 | 6篇 |
1970年 | 7篇 |
1966年 | 3篇 |
排序方式: 共有1139条查询结果,搜索用时 15 毫秒
61.
62.
Aspergillus endocarditis in chronic granulomatous disease 总被引:2,自引:0,他引:2
We report the first case, to our knowledge, of Aspergillus endocarditis in chronic granulomatous disease in a patient who also had an atrial septal defect. A diagnosis was made on culture of the organism from the mass despite extensive prior investigation. The presence of distinctive skin lesions as a diagnostic clue of fungaemia is highlighted. Possible advances in diagnosis by detection of fungal cell wall components and in prophylaxis by use of itraconazole are referred to. We conclude that fungal endocarditis should be considered in this condition, especially in the presence of a structural heart defect. 相似文献
63.
OBJECTIVE: To verify whether advantages can derive from the implementation of preimplantation genetic diagnosis for aneuploidy in patients with a poor prognosis of full-term pregnancy, compared with conventional treatment procedures. DESIGN: A randomized, controlled study. SETTING: Reproductive Medicine Unit of the Società Italiana Studi Medicina della Riproduzione, Bologna, Italy. PATIENT(S): In a total of 262 stimulated cycles, women presented with the following poor-prognosis indications: maternal age of > or =36 years (n = 157), > or =3 previous IVF failures (n = 54), and an altered karyotype (n = 51). After giving consent, 127 patients underwent preimplantation genetic diagnosis for aneuploidy, whereas 135 controls underwent assisted zona hatching. INTERVENTION(S): Analysis of chromosomes XY, 13, 14, 15, 16, 18, 21, and 22 was carried out with the fluorescence in situ hybridization technique in a blastomere biopsied from day 3 embryos. Assisted zona hatching was performed on day 3 embryos from the control group. MAIN OUTCOME MEASURE(S): Embryo morphology and chromosomal status, number of transferred embryos, clinical pregnancies, implantation rates, and abortions. RESULT(S): In the study group, 717 embryos were analyzed by fluorescence in situ hybridization, and 60% were chromosomally abnormal. A mean of 2.3+/-0.9 euploid embryos were transferred in 99 cycles, resulting in 37 clinical pregnancies (37%) and a 22.5% ongoing implantation rate. In the control group, 126 cycles were performed with 3.2+/-1.3 embryos transferred, yielding 34 clinical pregnancies (27%) and a 10.2% ongoing implantation rate. CONCLUSION(S): The advantage of selecting embryos with a normal chromosome complement has an immediate impact on the ongoing implantation rate, especially in patients aged > or =38 years and carriers of an altered karyotype. 相似文献
64.
Gianaroli L Magli MC Munné S Fortini D Ferraretti AP 《Journal of assisted reproduction and genetics》1999,16(4):170-175
Purpose:
Following preimplantation genetic diagnosis of aneuploidy, embryo transfer was executed on day 4, with the aim of providing more time for expanding from six to nine the number of diagnosed chromosomes per single cell (Group 2; 45 cycles). The results obtained were compared to those derived from conventional day 3 transfer (Group 1; 71 cycles).
Methods:
For multicolor fluorescence in situ hybridization analysis, two panels of probes were used: the first, specific for chromosomes XY, 13, 16, 18, and 21, was tested in all patients (Groups 1 and 2); the second was implemented only in Group 2 patients for the detection of chromosomes 14, 15, and 22.
Results:
A total of 406 embryos underwent fluorescence in situ hybridization analysis in Group 1, and 236 in Group 2. Comparable percentages of both chromosomal abnormalities (61% and 62%) and pregnancy and implantation rates (36% and 24.5% in Group 1, 41% and 23.6% in Group 2) resulted, regardless of the higher mean age in Group 2.
Conclusions:
The diagnosis of the nine chromosomes which are most frequently associated with aneuploidy in humans could have an immediate impact on the rate of spontaneous abortions. Additional advantages are represented by the more accurate morphological evaluation of euploid embryos; the advanced compaction, which means that embryos are less exposed to damage during the transfer procedure; and the possibility of performing a reanalysis in cases where a fluorescence in situ hybridization diagnosis is not obtained. 相似文献
65.
Purpose:
Our purpose was to study aneuploidy frequencies of chromosomes 1, 4, 6, 7, 14, 15, 17, 18, and 22 in cleavage-stage embryos. These frequencies were compared to spontaneous abortion data to determine differences in survival rate of their aneuploidies.
Methods:
One hundred ninety-four embryos were analyzed with multicolor fluorescence in situ hybridization. Embryos were divided into three maternal age groups: 20 to 34.9 years, (2) 35 to 39.9 years, and (3) 40 years and older. Embryos were also divided into two developmental and morphological groups: arrested and nonarrested embryos.
Results:
The rate of aneuploidy was 14.51%, 14.10%, and 31.48% for age groups 1, 2, and 3, respectively (P < 0.005). The chromosomes most frequently involved in aneuploidy events were 22, 15, 1, and 17.
Conclusions:
The chromosomes most involved in spontaneous abortions are not necessarily the ones causing a decrease in implantation rates with maternal age. Other aneuploidies, such as for chromosomes 1 and 17, may seldom implant or die shortly after implantation. 相似文献
66.
67.
Human myeloid alpha 3-fucosyltransferase is involved in the expression of the sialyl-Lewis(x) determinant, a ligand for E- and P-selectin 总被引:1,自引:0,他引:1
Easton EW; Schiphorst WE; van Drunen E; van der Schoot CE; van den Eijnden DH 《Blood》1993,81(11):2978-2986
The sialyl-Lex determinant (NeuAc alpha 2-->3Gal beta 1-->4[Fuc alpha- 1-->3]GlcNAc) has been identified as a major ligand in the selectin- mediated adhesion of neutrophils and monocytes to activated endothelium or platelets. This carbohydrate epitope is formed by the sequential action of alpha 3-sialyltransferase and alpha 3-fucosyltransferase on N- acetyllactosamine (Gal beta 1-->4GlcNAc) disaccharide termini of glycoconjugates. We have addressed the role of the human myeloid alpha 3-fucosyltransferase in the expression of this epitope at the leucocyte surface by determining its activity in human-mouse leukemic cell hybrids (WEGLI), normal human granulocytes and chronic myeloid leukemia (CML) cells using sialylated and desialylated glycoproteins and oligosaccharides as acceptor substrates. In contrast to what has been reported for the myeloid-type enzyme, we found that the alpha 3- fucosyltransferase of the cells studied can use sialylated acceptors be it that the activity is several times lower than with asialo- substrates. Characterization of the product obtained with a sialylated oligosaccharide indicated that the enzyme can catalyze the formation of the sialyl-Le(x) structure. Flow cytometry of the WEGLI cells using a sialyl-Le(x)-specific monoclonal antibody (MoAb) showed that these cells indeed express sialyl-Lex at their surface, provided that they contain human chromosome 11. Earlier the presence of this chromosome had been correlated with the expression of alpha 3-fucosyltransferase activity. In addition to sialyl-Le(x), WEGLI cells containing chromosome 11 showed high-expression levels of related structures recognized by antibodies VIM-2 and VIM-8, suggesting that fucose addition can occur at both distal and proximal GlcNAc residues in poly- N-acetyl-lactosaminoglycan sequences. Based on the human chromosome contents it could be ruled out that the alpha 3-fucosyltransferase of WEGLI cells is a Lewis-type alpha 3/4- or plasma-type alpha 3- fucosyltransferase, the genes of which have been mapped to chromosome 19. It is concluded that the enzyme studied is of the myeloid-type and indeed is involved in the synthesis of sialyl-Le(x) (and also VIM-2 and VIM-8 structures) in leukocytes provided that its expression is at a sufficiently high level. 相似文献
68.
69.
70.