全文获取类型
收费全文 | 847篇 |
免费 | 52篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 38篇 |
妇产科学 | 8篇 |
基础医学 | 66篇 |
口腔科学 | 11篇 |
临床医学 | 98篇 |
内科学 | 219篇 |
皮肤病学 | 21篇 |
神经病学 | 23篇 |
特种医学 | 146篇 |
外科学 | 117篇 |
综合类 | 24篇 |
预防医学 | 7篇 |
眼科学 | 5篇 |
药学 | 54篇 |
中国医学 | 3篇 |
肿瘤学 | 101篇 |
出版年
2021年 | 4篇 |
2020年 | 3篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 21篇 |
2014年 | 16篇 |
2013年 | 19篇 |
2012年 | 9篇 |
2011年 | 13篇 |
2010年 | 32篇 |
2009年 | 27篇 |
2008年 | 19篇 |
2007年 | 46篇 |
2006年 | 19篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 20篇 |
2001年 | 22篇 |
2000年 | 12篇 |
1999年 | 17篇 |
1998年 | 48篇 |
1997年 | 51篇 |
1996年 | 60篇 |
1995年 | 33篇 |
1994年 | 36篇 |
1993年 | 23篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 37篇 |
1988年 | 33篇 |
1987年 | 26篇 |
1986年 | 30篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 17篇 |
1981年 | 17篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 12篇 |
1974年 | 4篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有946条查询结果,搜索用时 0 毫秒
1.
2.
BACKGROUND: A simple, rapid, inexpensive method for measuring the flow in a
patient's vascular access would permit routine monitoring during
haemodialysis, and hence provide information of access graft deterioration
sufficiently early to increase the success of minimally invasive remedial
procedures. This paper reports the validation of such a method in animals.
METHODS: A PTFE graft was implanted in sheep between the carotid artery and
the jugular vein. While the sheep was under general anaesthesia and on an
haemodialysis circuit, ultrasound velocity in its blood was perturbed by
the injection of a 5-10 ml bolus of isotonic NaCl. The pump tubing flow was
measured by a transit-time blood flow meter. This flow was combined with
the areas of perturbation generated by the injection before and after
mixing in the access flow to estimate graft flow. The calculated graft flow
was compared to flow measured directly by a transit-time probe on the same
carotid artery. RESULTS: Over a 10-fold range, 120-1260 ml/min, graft flow
measured by ultrasound velocity dilution agreed well with graft flow
measured directly with a scatter of 76 ml/min about the regression line.
CONCLUSION: Ultrasound velocity dilution provides a method for measuring
flow in the graft accurate enough for clinical evaluation of patients on
dialysis.
相似文献
3.
Recurrent thyroid cancer. Role of surgery versus radioactive iodine (I131) 总被引:1,自引:0,他引:1 下载免费PDF全文
OBJECTIVE: This retrospective study compared treatment and survival of patients with recurrent well-differentiated thyroid cancer that was diagnosed exclusively by I131 scanning, or by clinical examination. SUMMARY BACKGROUND DATA: Despite the usual excellent prognosis of differentiated thyroid cancer, approximately half of patients who developed a recurrence eventually succumb to the disease. It has been speculated, but not proven, that recurrent disease detected solely by I131 scanning may offer a better prognosis than recurrences detected clinically and be amendable to I131 ablative therapy without the addition of surgical resection. METHODS: Seventy-four cases of recurrent differentiated thyroid cancer were identified retrospectively and examined regarding the location of recurrence, mode of detection of recurrent disease, treatment of recurrence, and outcome of patients. Using Fischer exact testing, outcome results for recurrences detected exclusively by I131 scan was compared to that of clinically diagnosed recurrences; among clinically detected recurrent cases, treatment with surgery only was compared to surgery/I131 ablation. Kaplan-Meier actuarial survival curves were generated for clinically detected recurrent cancer treated by surgery only and compared to those treated by surgery and I131 ablation using Gehan-Wilcoxon and log-rank analysis. RESULTS: Recurrences located most commonly were regional (53%), followed by local (28%), distant metastasis (13%), and combined locoregional (6%). Among patients whose recurrence was detected scintigraphically, only 9.5% had persistence of disease or were dead of disease compared to 54.0% of patients with clinically detected recurrences. Radioactive iodine ablation in scintigraphically detected recurrences salvaged 18 of 20 patients (90%). Among clinically detected recurrences, surgery alone salvaged 12 of 21 patients (57%), whereas the addition of I131 ablation to surgery salvaged only 3 of 15 patients (20% p = 0.05). CONCLUSION: The probability of dying or living with persistent disease after treatment of recurrent thyroid cancer is less for I131 detected recurrences compared to clinically diagnosed recurrences; I131 ablation without surgery constitutes adequate therapy for scintigraphically detected recurrences. In clinically recurrent disease, the addition of I131 ablation to curative resection does not appear to improve survival. 相似文献
4.
Advanced pelvic cancer is a formidable challenge to surgical resection. These tumors commonly invade the bony pelvis, may involve other viscera, and usually have been irradiated previously. The authors are presenting experience with 76 patients who had composite resection of posterior or lateral pelvic malignancy. Fifty-eight patients had secondary cancers involving the musculoskeletal pelvis. This included 47 patients with advanced carcinoma of the rectum (41 curative, 6 palliative), 10 epidermoid cancers of the anorectum (8) or cervix (2), and 1 bladder cancer. Among the 18 patients with primary pelvic tumors were three patients with chordomas, six with bone tumors (osteosarcoma chondrosarcoma, grade III giant cell tumor), and nine with soft tissue tumors. All required major resection of the sacrum or pelvic side walls, and one half had an additional exenterative procedure. The overall mortality rate was 7.9%. Long-term estimated survival was 24% in patients having curative resection of recurrent rectal cancer, and 22.5% in 10 patients with advanced epidermoid cancer. Fifty per cent of patients with primary bone or soft tissue tumors survived from 13 to 88 months. Most patients had reasonable return of function, and were able to return to work or resume their normal previous lifestyle. 相似文献
5.
The techniques for revascularization in the neurocranium, skull base, and neck continue to evolve at an exciting pace. In this body of literature, however, techniques for harvesting radial artery and saphenous vein grafts are mainly reported using traditional open techniques. Minimally invasive procedures are fast becoming an alternative to open techniques in many fields and have the potential to become the standard of care. The cardiovascular literature is replete with reports of endoscopically harvested vascular grafts. This article reviews both methods, since the current state of the art involves knowledge of open and endoscopic harvesting techniques. 相似文献
6.
M Kaplan HJ Vreman C Hammerman C Leiter B Rudensky MG MacDonald DK Stevenson 《Acta paediatrica (Oslo, Norway : 1992)》1998,87(4):455-457
The incidence (%) of hyperbilirubinemia (serum bilirubin ≥257 μmol/l) was similar in neonates with a combination of ABO incompatibility and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency (45%), with ABO incompatibility (54%) or G-6-PD deficiency (37%), alone (ns). Carboxyhemoglobin values, corrected for inspired CO, were similarly elevated in all three groups (0.87 ± 0.32%, 0.82 ± 0.29%, 0.76 ± 0.18%, respectively, ns), but correlated with bilirubin only in those with ABO incompatibility alone. ABO-incompatible/G-6-PD-deficient neonates, compared with those with either condition alone, are not at increased risk for hemolysis or hyperbilirubinemia. 相似文献
7.
The effects of co-culture with human fibroblasts on human embryo development in vitro and implantation 总被引:5,自引:0,他引:5
Wetzels AM; Bastiaans BA; Hendriks JC; Goverde HJ; Punt-van der Zalm AP; Verbeet JG; Braat DD 《Human reproduction (Oxford, England)》1998,13(5):1325-1330
In a human in-vitro fertilization (IVF) programme, the effect of co-
culture of embryos with human fibroblasts was evaluated with respect to
pregnancy rate and embryo development. Patients were included in the study
after giving informed written consent. The IVF treatments were randomly
assigned by stratification of both age (<36 versus > or =36 years)
and previous IVF attempts (yes versus no). After fertilization was
established, the zygotes were transferred to a 4-well dish with or without
fibroblasts and cultured for 2 days. On the third day after ovum pick-up
(OPU), cell number and quality [5 (good) to 1 (poor)] of the embryos were
scored and a maximum of three embryos was transferred. Supernumerary
embryos of good quality were cryopreserved. The design of this study was a
group sequential trial with the objective of detecting differences between
pregnancy rates following IVF with conventional incubation or incubation in
co-culture with fibroblasts. This design included one evaluation at
half-way data collection. In the study, 148 patients had an OPU, of whom 77
were allocated to the co-culture group. There was no statistically
significant difference in pregnancy rate, cell number and embryo quality
between the two groups. The ongoing pregnancy rate per embryo transfer was
27% in co-culture and 30% in the conventional culture group. The
implantation rates per transferred embryo were 17 and 18% respectively.
Using a multivariate logistic regression model for the probability of
ongoing pregnancies, the odds ratio of co-culture, adjusted for age and
previous IVF attempts, was not statistically significant. In conclusion,
co-culture with human fibroblasts does not contribute to an improvement of
embryo quality nor to a higher pregnancy rate after IVF in an unselected
group of patients.
相似文献
8.
Endothelin receptor expression in human decidua 总被引:3,自引:1,他引:3
Kohnen G; Campbell S; Irvine GA; Church HJ; MacLachlan F; Titterington M; Cameron IT 《Molecular human reproduction》1998,4(2):185-193
The endothelins are signalling peptides that act via two receptors, ET(A)
and ET(B). In the human endometrium, endothelin receptors have been
demonstrated in glands and stroma and have been shown to vary during the
course of the menstrual cycle. The present study was undertaken to
determine whether or not expression of endothelin receptors changes during
pregnancy or after administration of exogenous progestagens. The expression
of the receptors was correlated with the appearance of basement membrane
components during decidualization of the endometrial stroma. Decidual
specimens (n = 15) were obtained during the first trimester of pregnancy
and 10 at term. Sixteen pairs of endometrial biopsies were obtained from
women with menorrhagia before and after exposure to exogenous progestagens.
A total of 15 hysterectomy specimens were used as controls for the
expression of stromal basement membrane proteins in the absence of
decidualization. Autoradiography was carried out with selective ligands for
ET(A) ([125I]-PD 151242) and ET(B) ([125I]-BQ3020). The distribution of
ligand binding was then compared with the distribution of laminin alpha2
light chain and collagen IV. ET(A), ET(B), laminin alpha2 light chain, and
collagen IV were expressed in stromal decidual cells in the first trimester
of pregnancy. ET(B) was also found on endometrial glandular epithelium.
Quantitative macro-autoradiography and multiple regression analysis
demonstrated a highly significant positive correlation (P < 0.001)
between expression of ET(B) and laminin alpha2 light chain. In the third
trimester qualitative examination suggested a reduction of ET(A) in the
stroma. Progestagen-induced decidua exhibited a similar pattern to that
found in first trimester decidua. This study has demonstrated up-regulation
of ET(B) during the progesterone- dependent process of decidualization and
suggests a paracrine or autocrine role for endothelins in the decidua.
相似文献
9.
Induction of a differentiated ciliated cell phenotype in primary cultures of Fallopian tube epithelium 总被引:5,自引:1,他引:5
Human Fallopian tubal epithelial cells in culture lose morphological
features associated with the epithelium in situ and the extent to which
they retain their in-vivo phenotype or function is unknown. In order to
address this question, immunocytochemical markers were identified which
distinguish secretory (HMFG2+, LhS28-) from ciliated (HMFG2-, LhS28+)
epithelial cells in tissue sections of Fallopian tube. These markers were
used to analyse the phenotype of tubal cells in vitro. Primary cultures of
human tubal epithelial cells were seeded onto glass and grown to confluence
before addition of oestradiol-17beta. In the absence of hormone, tubal
epithelial cells expressed cytokeratins and nuclear receptors for oestrogen
and progesterone and adopted a homogeneous (HMFG2+, LhS28-) secretory cell
phenotype. Following the addition of oestradiol-17beta, a proportion of
cells became positive for LhS28. The induction of a ciliated epithelial
cell phenotype was confirmed by scanning electron microscopy, where on
permeable collagen membranes, approximately one-third of tubal epithelial
cells became ciliated in the presence of oestradiol-17beta. We suggest that
in vitro, tubal epithelial cells adopt an immature secretory-like phenotype
and that oestrogen can induce differentiation to a ciliated epithelial cell
phenotype.
相似文献
10.
David P. Shrayer Bernard Cole Vincent J. Hearing Stanley F. Wolf Harold J. Wanebo 《Clinical & experimental metastasis》1999,17(1):73-80
Interleukin (IL)-12 can activate cytotoxic lymphocytes, stimulate natural killer cell activity, induce the production of INF- and inhibit the development of various experimental tumors. We previously demonstrated that immunotherapy of melanoma bearing mice with an irradiated melanoma vaccine (IMV) coupled with IL-2 or GM-CSF had beneficial effects against primary melanoma growth and against subsequent spontaneous metastasis. We also had found that treatment of melanoma bearing mice with IL-12 (300 ng/day) for 4 weeks inhibited the development of primary melanoma tumors in 40% of mice. The purpose of this study was to investigate the efficacy of combined therapy of experimental melanoma with an IMV prepared from B16F10 melanoma cells coupled with IL-12 treatment. C57BL/6 mice were challenged subcutaneously in the tail with B16F10 melanoma cells and by the 45th day, more than 50% of the mice had developed visible primary melanoma tumors at the injection site. Subsequent immunotherapy of mice with IMV, when coupled with IL-12, provided partial inhibition of primary melanoma tumor growth. Optimal results against primary tumor growth were observed when IMV therapy was coupled with IL-12 at a dose of 50 ng/day. Combination of IMV with IL-12 at a dose of 100 ng/day significantly reduced melanoma metastasis to the lungs compared with control mice, and an improvement in mean survival time was observed in mice treated with a combination of IMV with IL-12 (300 ng/day). 相似文献