全文获取类型
收费全文 | 836篇 |
免费 | 92篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 73篇 |
妇产科学 | 12篇 |
基础医学 | 101篇 |
口腔科学 | 30篇 |
临床医学 | 78篇 |
内科学 | 171篇 |
皮肤病学 | 21篇 |
神经病学 | 84篇 |
特种医学 | 139篇 |
外科学 | 54篇 |
综合类 | 42篇 |
预防医学 | 30篇 |
眼科学 | 30篇 |
药学 | 30篇 |
中国医学 | 1篇 |
肿瘤学 | 34篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 24篇 |
2017年 | 11篇 |
2016年 | 26篇 |
2015年 | 27篇 |
2014年 | 37篇 |
2013年 | 45篇 |
2012年 | 38篇 |
2011年 | 24篇 |
2010年 | 52篇 |
2009年 | 47篇 |
2008年 | 27篇 |
2007年 | 38篇 |
2006年 | 18篇 |
2005年 | 25篇 |
2004年 | 11篇 |
2003年 | 16篇 |
2002年 | 9篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 41篇 |
1997年 | 43篇 |
1996年 | 42篇 |
1995年 | 37篇 |
1994年 | 24篇 |
1993年 | 29篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1884年 | 1篇 |
排序方式: 共有936条查询结果,搜索用时 15 毫秒
81.
82.
In this study we examined the effect of mitogens and epidermal cells in inducing a Sezary cell morphology in normal peripheral blood lymphocytes. Peripheral blood mononuclear cells from six healthy volunteers were stimulated with the mitogens phytohemaglutinin and concanavalin A, and also cocultivated with human epidermal cell cultures. Incubation times with mitogens and epidermal cells were four days and stimulation of the lymphocytes by mitogens was confirmed by standard 3H-thymidine uptake. Standard transmission electron microscopy showed that in the mitogen-driven system 20% to 60% (33 +/- 15%) and in the epidermal cell-driven system 5% to 15% (8 +/- 4%) of the lymphoid cells exhibited mild to moderate indentation of the nuclei with nuclear contour indices (NCI) of 4.6 to 6.5 but no Sezary cells were observed (cells with NCI greater than 6.5 and up to 19.2). In the mitogen- stimulated preparation 2% to 5% (3 +/- 1%) of the lymphoid cells showed nuclear multilobulation resembling the cells seen in adult T cell lymphoma/leukemia. Incubation of mononuclear cells for longer periods of up to 4 weeks with mitogens and exogenous IL-2 resulted in no further morphologic changes. Using an indirect immunogold technique at the electron microscopic level, the cells showing nuclear indentation or lobulation were shown to bear both T helper (CD4) and T suppressor (CD8) cell phenotypes in a similar ratio to the total numbers of T helper and T suppressor cells present. Mitogens and epidermal cells are thus not able to induce a morphologic change to Sezary cells in normal peripheral blood lymphocytes. 相似文献
83.
Elevated numbers of primitive Philadelphia chromosome-positive (Ph+) progenitors, including long-term culture-initiating cells (LTC-IC) as well as colony-forming cells (CFC), have been previously described in the blood of patients with chronic myeloid leukemia (CML) in chronic phase with high white blood cell counts. In the present study, which focused primarily on an analysis of circulating progenitors present in such patients at diagnosis, we discovered the frequent and occasionally exclusive presence of circulating normal (Ph-) LTC-IC, often at levels above those seen for LTC-IC in the blood of normal individuals. The presence of detectable numbers of circulating Ph- LTC-IC was independent of the fact that the same peripheral blood samples also contained elevated numbers of predominantly or exclusively Ph+ CFC. Interestingly, both the Ph+ and Ph- LTC-IC in these samples were CD34+CD71- and variably CD38- and Thy-1+, as previously documented for LTC-IC in normal marrow. Thus, neither CD38 nor Thy-1 expression was useful for discriminating between Ph+ and Ph- LTC-IC in mixed populations. Nevertheless, an association of these phenotypes with LTC- IC function did allow highly enriched (> 5% pure) suspensions of either Ph+ or Ph- LTC-IC to be obtained from selected samples of CML blood in which the initial LTC-IC population was either predominantly Ph+ or Ph- , respectively. These findings suggest that the mechanisms causing mobilization of leukemic stem cells in untreated CML patients may affect their normal counterparts. They also indicate a possible new source of autologous cells for the support of intensive therapy of CML patients. Finally, they provide a method for obtaining the most highly purified populations of Ph+ LTC-IC described to date. This method should be useful for further analyses of the molecular activities of these very primitive neoplastic cells. 相似文献
84.
85.
Obesity in children may cause overt clinical disease in childhood. The complex endocrine and metabolic changes of obesity and insulin resistance in adolescents result in hyperinsulinemia, dyslipidemia, hypertension, steatohepatitis, glucose intolerance, type 2 diabetes, acanthosis nigricans and ovarian hyperandrogenemia, commonly known as polycystic ovarian syndrome (PCOS). Type 2 diabetes and PCOS in adolescents are new endocrine diseases in this age group that require unique approaches to diagnosis and treatment. The direct correlation between duration of disease and control of the disease, and subsequent long term complications of these two diseases, predict serious morbidity in young adult life for the affected adolescents. Pediatricians have an important role in the prevention, diagnosis and treatment of obesity, insulin resistance syndrome, type 2 diabetes and PCOS. 相似文献
86.
Selective transfer of cryopreserved human embryos with further cleavage after thawing increases delivery and implantation rates 总被引:6,自引:10,他引:6
Van der Elst J; Van den Abbeel E; Vitrier S; Camus M; Devroey P; Van Steirteghem AC 《Human reproduction (Oxford, England)》1997,12(7):1513-1521
We investigated whether further in-vitro culture of human multicellular
embryos that survive cryopreservation can select the viable embryos for
transfer. Embryos for cryopreservation were supernumerary multicellular
embryos obtained after in-vitro fertilization (IVF) and intracytoplasmic
sperm injection (ICSI) treatments, with <20% of their volume filled with
anucleate fragments. These had been cryopreserved using a slow-freezing and
slow-thawing protocol with 1.5 M dimethylsulphoxide as the cryoprotectant.
From the start of our cryopreservation programme until September 12, 1994,
the thawing strategy was to thaw frozen embryos up to the exact number
needed for transfer. Embryos for transfer were selected on the basis of
their morphological appearance and embryo transfer to the patient was done
on the day of thawing. From September 12, 1994 onwards we used a more
selective thawing strategy where a cohort of up to a maximum of 12 frozen
embryos per patient is thawed from which embryos of the best morphological
quality, and which are furthest advanced in terms of cleavage after a 24 h
in-vitro culture period in Menezo B2 medium, are selected. We took delivery
rates, embryo implantation rates and birth rates into account to see if
there is any difference between the following three types of transfers
used: 187 transfers exclusively of embryos having continued to cleave after
thawing, 107 mixed transfers of embryos with and without further cleavage
and 53 transfers exclusively of embryos with no further cleavage. The
overall outcome in terms of delivery rate and embryo implantation and birth
rates were not different between the new and the earlier thawing policies
(6.6, 5.2 and 3.6% versus 6.0, 4.1 and 2.7% respectively). Only when a
distinction was made between transfers on the basis of the presence of
embryos with further cleavage, did the advantage of selection on the basis
of cleavage capacity become evident. Significantly higher delivery and
embryo implantation and birth rates (11.2, 7.7 and 6.5% respectively) were
recorded with transfers exclusively of embryos with further cleavage versus
mixed transfers of embryos with and without further cleavage (1.9, 2.9 and
0.6% respectively). Fifty-three transfers exclusively of embryos with no
further cleavage did not lead to any delivery. Our results demonstrate that
selection of human multicellular embryos which survive cryopreservation and
continue to cleave in vitro can significantly improve the delivery rate per
transfer and the implantation rate per transferred embryo.
相似文献
87.
Viability of partially damaged human embryos after cryopreservation 总被引:10,自引:13,他引:10
Van den Abbeel E; Camus M; Van Waesberghe L; Devroey P; Van Steirteghem AC 《Human reproduction (Oxford, England)》1997,12(9):2006-2010
In our centre, embryos are judged to have survived cryopreservation if at
least half of the initial number of blastomeres remain intact. Therefore
both fully intact and partially damaged embryos are transferred. The aim of
this study was to investigate the viability of partially damaged human
embryos after cryopreservation. We retrospectively analysed the
implantation and in-vivo development of embryos which were either fully
intact or had lost some blastomeres after cryopreservation. Oocytes were
collected following stimulation with the gonadotrophin-releasing hormone
(GnRH)-agonist Buserelin and human menopausal gonadotrophin. Supernumerary
multicellular embryos with not more than 20% of their volume filled with
anucleate fragments were frozen on day 2 or day 3 of the cycle using a slow
cooling procedure with dimethylsulphoxide as the cryoprotectant. Following
slow thawing, 431 fully intact embryos were transferred in 314 embryo
transfer procedures and 488 partially damaged embryos were transferred in
327 such procedures. The percentage of gestational sacs with fetal
heartbeat obtained after transfer of fully intact embryos was almost three
times higher than that after transfer of partially damaged embryos (11.4
versus 3.5%). Forty-five children (birth rate 10% per embryo transfer) were
born after transfer of fully intact embryos and 14 after transfer of
embryos from which some blastomeres had been lost following
cryopreservation. In conclusion, although children have been delivered
after transfer of partially damaged embryos, the aim of a cryopreservation
programme must be to obtain fully intact embryos after thawing.
相似文献
88.
黄高升 《中国医学科学杂志(英文版)》1994,9(1):16-19
CORRELATIONBETWEENTHENUMBEROFMITOTICFIGURESANDTHEPERCENTAGEOFKi67-POSITIVECELLS INNON-HODGKIN’SLYMPHOMASHuangGaosheng;(黄高升)Fe... 相似文献
89.
Rabbits fed a vitamin E-deficient diet developed severe muscular dystrophy in 3-4 wk, but they did not become anemic. Nevertheless, reticulocyte counts increased in deficient rabbits (3.2%) compared to control rabbits (0.9%), and erythroid hyperplasia was evident in the bone marrow. Comparing deficient rabbits to controls, the plasma iron concentration was lower (134.4 versus 206.6 microgram/dl); the TIBC was higher (335.9 versus 228.3 microgram/dl); the whole blood protoporphyrin concentration was higher (131.6 versus 81.7 microgram/dl); and the total iron content was lower in spleen (71 versus 153 microgram), higher in skeletal muscle (4956 versus 3054 microgram), and unchanged in bone marrow, liver, and heart. Studies of iron absorption and excretion using 59Fe showed no abnormalities in deficient rabbits. There were abnormalities of ferrokinetics, however. The half-time of disappearance of 59Fe was shorter (100.6 versus 169.4 min), the plasma iron turnover was greater (1.25 versus 0.95 mg/dl blood/day), and the reappearance of 59Fe in circulating erythrocytes at day 9 was greater (77.2% versus 57.2%) in deficient rabbits. Anemia induced by phlebotomy accentuated the abnormal iron metabolism of deficient rabbits, and the animals were unable to correct the anemia. These findings show that vitamin E deficiency in rabbits causes abnormal erythropoiesis associated with abnormal iron metabolism and sequestration of iron in skeletal muscle. 相似文献
90.