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991.
SCHWANN CELLS AND THE REGROWTH OF AXONS IN THE MAMMALIAN CNS: A REVIEW OF TRANSPLANTATION STUDIES IN THE RAT VISUAL SYSTEM 总被引:2,自引:0,他引:2
A. R. Harvey G. W. Plant M. M. L. Tan 《Clinical and experimental pharmacology & physiology》1995,22(8):569-579
1. We have used peripheral nerve transplants or cultured Schwann cells grafted in association with different types of polymer to study axonal regrowth in the rat visual system. In some instances the glia were co-grafted with fetal tectal tissue. 2. The studies have two main aims: (i) to determine whether retinal axons can be induced to regrow at a site distant from their cell soma, that is, after damage to the brachial region of the optic tract; (ii) to determine whether retinal axons exposed to Schwann cells retain the ability to recognize their appropriate target neurons in CNS tissue. 3. In brachial lesion studies, Schwann cells were placed in the lesion site in association with nitrocellulose papers, within polycarbonate tubes in the presence or absence of a supporting extracellular matrix (ECM), or within polymer hydrogel scaffolds. Autologous sciatic nerve grafts were also used. Immuno-histochemical studies revealed the presence of regenerating axons within all polymer bridges. Regrowth of retinal axons was also seen, however, growth was not extensive and was limited to the proximal 1–1.5 mm of the implants. 4. In target innervation experiments, two surgical paradigms were developed. In one experiment, a segment of sciatic nerve was autografted onto the transected optic nerve in adult rats and the distal end of each graft was placed adjacent to fetal tectal (target) tissue implanted into the frontal cortex. To date, we have not been able to demonstrate selective recognition of target regions within tectal transplants by retinal axons exiting the sciatic nerve implants. 5. In the second experiment, Schwann cells were mixed with fetal tectal cells and co-grafted to the midbrain of newborn host rats. Schwann cells altered the characteristic pattern of host retinal growth into tectal grafts; in some cases axons were induced to grow away from appropriate target areas by nearby co-grafted Schwann cells. 6. In summary, Schwann cell/polymer scaffolds may provide a useful way of promoting the regrowth of damaged axons in the CNS, however: (i) in adults, at least, their effectiveness is reduced if they are located at a distance from the cell bodies giving rise to regenerating axons; (ii) in some circumstances exposure to a peripheral glial environment may affect the capacity of regenerating axons to recognize appropriate target cells in the CNS neuropil. 相似文献
992.
运动大鼠不同水平蛋白质摄入量研究 总被引:3,自引:1,他引:2
实验采用Wistar雄性大鼠,三种蛋白质摄入水平(7%、17%、27%),观察运动对大鼠蛋白质代谢的影响,为探讨运动和体力劳动人群适宜蛋白质需要量研究提供实验室依据。结果表明:运动可降低氮平衡值,运动后,血清尿素氮和氨基酸水平均增高,排肠肌氮含量降低。不同蛋白质摄入水平的大鼠影响程度各异。17%和27%蛋白质摄入水平大鼠体重增长无明显差别,均优于7%蛋白质摄入水平的大鼠。运动后,7%蛋白质摄入水平大鼠的蛋白质分解作用较强,未见27%蛋白质摄入水平优于17%者,对于急性高强度运动,17%蛋白质摄入水平可能是适宜的。 相似文献
993.
994.
995.
J. G. BLIGH 《Medical education》1992,26(6):497-502
Self-directed learning is a natural way for adults to learn. Vocational training for general practice is a preparation for unsupervised clinical work that will be supported, in the main, by continuing medical education. This study uses the Self-Directed Learning Readiness Scale to investigate factors influencing readiness for such learning among a sample of general practice trainees. Three principal factors emerged from analysis: enjoyment and enthusiasm for learning; a positive self-concept as a learner and a factor suggesting the possibility of a 'reproducing' orientation to learning. These factors may reflect approaches to learning in general rather than these adopted for professional learning, but offer helpful pointers for the development of both vocational training and of continuing medical education. 相似文献
996.
The effect of oral premedication was investigated in a double-blind, randomised trial in 85 children undergoing tonsillectomy and/or adenoidectomy. Orally administered midazolam 0.5 mg.kg−1 given 30 min pre-operatively was compared with trimeprazine 2 mg.kg−1 given 90 min pre-operatively and a placebo preparation. Compliance, sedation and ease of induction were assessed as were the duration and quality of recovery. Following premedication with midazolam none of the patients was anxious, crying or distressed on leaving the ward, compared with 2/28 in the trimeprazine group and 5/28 in the placebo group (p =0.0007). More patients were calm and quiet on arrival in the anaesthetic room following midazolam than following trimeprazine, with both premedicant agents comparing favourably with placebo. There was no significant difference between the three groups in the time to recovery or the sedation score on discharge to the ward. Midazolam is a safe and effective oral premedicant for children. 相似文献
997.
Carcinoma of the male breast: Analysis of prognosis compared with matched female patients 总被引:6,自引:0,他引:6
Dr. Patrick I. Borgen MD Ruby T. Senie PhD William M. P. McKinnon MD Paul Peter Rosen MD 《Annals of surgical oncology》1997,4(5):385-388
Background: Considerable debate exists concerning the prognosis of breast cancer in male patients compared with that in female patients.
Some studies have observed worse prognosis for men; others suggested the higher mortality rates were primarily due to delayed
diagnosis.
Methods: Survival time from diagnosis with invasive disease to death resulting from breast cancer of 58 men treated between 1973 and
1989 was compared with survival of 174 women treated between 1976 and 1978 who were matched by stage of disease and age at
diagnosis. All patients were treated by mastectomy and axillary dissection.
Results: Tumors were ⩽2 cm in 70% of cases and 55% were free of axillary metastases. The histology of the tumors differed significantly
by gender (p<0.05). Significantly more men had estrogen receptor-positive tumors (87%) than did women (55%, p<0.001). Survival
at 10 years was similar for male and female patients. Multivariate analysis controlling for tumor size, number of positive
axillary lymph nodes, age at diagnosis, histology, and receptor status indicated no significant difference in survival of
male compared with female patients.
Conclusions: These data conflict with the conventional wisdom that breast cancer in men carries a worse prognosis than the disease in
women. Although histology of the tumor and receptor status differed by gender, these factors did not have an impact on survival
in these paired patients. Our data indicate that breast carcinoma in males is not biologically more aggressive than in females.
Presented at the 49th Annual Cancer Symposium of The Society of Surgical Oncology, Atlanta, Georgia, March 21–24, 1996. 相似文献
998.
A protein C deficient woman, with a past history of recurrent thrombosis and purpura fulminans, was successfully treated with protein C concentrate in the peripartum period. © 1992 Wiley-Liss, Inc. 相似文献
999.
A recent large increase in Caesarean section (CS) in Italy was the initial stimulus for a study to identify risk factors for CS and, if possible, to suggest strategies to counteract the rise. The study was conducted in three hospitals where a wide range of individual variables was collected from the clinical records and from personal interviews. Crude CS rates and odds ratios were evaluated for each single variable while logistic regression has been used to investigate possible confounding factors. The study involved 1316 consecutive deliveries. Crude CS rates were 29.4%, 15.7% and 16.1%. Variables identified as high risk factors were pre-eclampsia, previous CS, breech and other non-vertex presentations. Antenatal care under an obstetrician working in the same hospital, a low number of antenatal consultations, previous miscarriages, offer (by obstetrician) and request (by women) for CS showed significantly high odds ratios (ORs). Previous live births was strongly negatively associated with CS. No relationship between type of delivery and social status was observed while a physician factor was detected in all three hospitals where rates for different physicians ranged from 0% to 52.8%. Apart from the main medical indications for Caesarean section (previous CS, breech presentation), the results seem to indicate that individual practice style may be an important determinant of the wide variation in the rates of Caesarean delivery. While this may have been suspected before this study, these results are the first hard data to indicate that, in Italy, CS is widely performed for non-medical reasons. 相似文献
1000.
目的 探讨经鼻给予神经生长因子(NGF)对沙林染毒大鼠脑组织梨状皮质区神经元的影响.方法 建立大鼠沙林染毒模型,常规治疗后经鼻给予NGF或生理盐水,24 h后采用HE染色和免疫组织化学染色观察梨状皮质区神经元的变化.结果 与空白对照组相比,经鼻给予生理盐水的大鼠梨状皮质区可见较多变性、坏死的神经元,神经元数量[(404.75±25.17)个/mm2]明显减少(39.44%);而经鼻给予NGF组变性、坏死的神经元较少,神经元数量[(651.94±36.02)个/mm2]减少不明显.结论 经鼻给予NGF可以减轻沙林染毒大鼠梨状皮质区损伤程度.经鼻给予NGF有可能成为针对沙林所致脑损伤的有效治疗手段. 相似文献