全文获取类型
收费全文 | 4477篇 |
免费 | 261篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 97篇 |
妇产科学 | 54篇 |
基础医学 | 642篇 |
口腔科学 | 139篇 |
临床医学 | 417篇 |
内科学 | 1039篇 |
皮肤病学 | 43篇 |
神经病学 | 645篇 |
特种医学 | 296篇 |
外科学 | 545篇 |
综合类 | 26篇 |
一般理论 | 1篇 |
预防医学 | 198篇 |
眼科学 | 19篇 |
药学 | 257篇 |
肿瘤学 | 326篇 |
出版年
2020年 | 34篇 |
2019年 | 39篇 |
2018年 | 48篇 |
2017年 | 36篇 |
2016年 | 62篇 |
2015年 | 77篇 |
2014年 | 69篇 |
2013年 | 122篇 |
2012年 | 135篇 |
2011年 | 162篇 |
2010年 | 97篇 |
2009年 | 112篇 |
2008年 | 166篇 |
2007年 | 193篇 |
2006年 | 154篇 |
2005年 | 187篇 |
2004年 | 180篇 |
2003年 | 166篇 |
2002年 | 156篇 |
2001年 | 160篇 |
2000年 | 146篇 |
1999年 | 157篇 |
1998年 | 94篇 |
1997年 | 66篇 |
1996年 | 81篇 |
1995年 | 57篇 |
1994年 | 43篇 |
1993年 | 53篇 |
1992年 | 92篇 |
1991年 | 116篇 |
1990年 | 110篇 |
1989年 | 98篇 |
1988年 | 105篇 |
1987年 | 110篇 |
1986年 | 96篇 |
1985年 | 91篇 |
1984年 | 78篇 |
1983年 | 67篇 |
1982年 | 53篇 |
1981年 | 35篇 |
1980年 | 37篇 |
1979年 | 58篇 |
1978年 | 55篇 |
1977年 | 48篇 |
1976年 | 47篇 |
1975年 | 50篇 |
1974年 | 57篇 |
1973年 | 42篇 |
1972年 | 46篇 |
1971年 | 52篇 |
排序方式: 共有4767条查询结果,搜索用时 15 毫秒
991.
Summary Intravenously (i.v.) injected horseradish peroxidase (HRP) which has leaked out of the vessels in a cryogenic cortical injury of adult mice is taken up into a large number of neurons resulting in two different forms of labeling.
Diffuse neuronal labeling of, the type previously reported in many conditions with vasogenic brain edema occurred particularly within the primary lesion. The other and more frequent type, here calledgranular neuronal labeling, was present in a wide zone immediately outside the injury. Such neurons contained HRP in numerous cytoplasmic granules and had the same characteristics as normal neurons accumulating HRP after retrograde axonal transport. By using highly sensitive histochemical methods for demonstration of HRP we could also follow bundles of labeled axons out from the primary lesion. Some of them passed the corpus callosum to the fronto-parietal cortex of the contralateral hemisphere.With this report we would like to put emphasize on certain phenomena occurring in neurons which previously have not been particularly recognized in studies on vasogenic brain edema. It can be assumed that in a focal brain lesion components from the edematous fluid and other wound substances can be taken up into nerve cell processes and then be intracellularly transported in different directions. In this way, nerve cell populations located in other brain areas and even in the contralateral hemisphere may be influenced by components from the primary injury.Supported by grants from the Swedish Medical Research Council, project 12X-03020 and Trygg-Hansa, Stokholm 相似文献
992.
The aim of the study was to compare the outcome of bridges supported by implants with bridges supported by a combination of implants and natural teeth abutments. The study comprised 23 patients with Applegate Kennedy Class I dentition in the mandible and a full upper denture. Implants ad modum Brånemark were inserted in the posterior areas of both mandibular quadrants. On one side, a bridge supported by 2 implants was constructed (Type I) and on the other side, a bridge supported by 1 tooth (mostly the canine or first premolar) and 1 implant was made (Type II). A total of 46 bridges were made and during the 3-year follow-up period, 4 Type I and 2 Type II bridges were lost. 8 out of 69 implants were lost during the 3-year follow-up, resulting in an implant survival rate of 88.4%. Marginal bone loss, one of several parameters, was evaluated on standardized intraoral radiographs. This was performed during the 1st and 2nd year of function and the total mean bone loss from loading was 0.46 mm and 0.56 mm, respectively. The bone loss during the 2nd year of function was significantly less, adjacent to implants supporting Type II bridges, than adjacent to implants supporting Type I bridges. Summarily, no disadvantages of combining of teeth and implants in the same bridge were found in this study. On the contrary, the slightly lower marginal bone loss adjacent to implants in Type II bridges may indicate that the bone reactions could be more favorable when bridges 1 are connected to both implants and teeth. 相似文献
993.
Eight patients, 3 with systemic lupus erythematosus (SLE) or "SLE-like" disease, 1 with sarcoidosis, and 4 with no connective tissue disease had transient ischemic attacks (TIA) or cerebral infarctions associated with high levels of anticardiolipin antibodies (ACA). Cerebral ischemic events included amaurosis fugax, recurrent hemispheric TIA, cerebral infarction, and multi-infarction dementia. Treatment with acetylsalicylic acid was ineffective in 3 patients. Warfarin, alone or in combination with dipyridamole or steroids, may reduce the risk of further cerebrovascular events. 相似文献
994.
Summary Infusion of hypertonic solutions into the carotid artery is one method by which the blood-brain barrier (BBB) can be opened transiently in experimental animals. This technique has also been tried in clinical situations in which an enhanced uptake of intravenously injected chemotherapeutic drugs into the brain is desired. We have previously found that infusion of hypertonic mannitol or urea into the carotid artery of the rat, leading to a BBB opening, is associated with light microscopic signs of cellular damage in the brain parenchyma. An electron microscopic study has now been made to obtain more detailed information about the events taking place in the rat brain 1 to 72 h after an intracarotid infusion of hyperosmolar solution of mannitol. Toluidine blue-stained semithin epon sections were also available for high-resolution light microscopy of brain samples from urea-infused animals. Intravenously injected Evan's blue dye was used to confirm that BBB opening had occurred as a consequence of the carotid infusions. The infused hemispheres had numerous structural changes. The dominating light microscopic alteration was the presence of multifocal lesions in the gray or the white matter with closely packed microvacuoles causing status spongiosus. Ultrastructurally the microvacuoles corresponded to very pronounced watery swelling of astrocytic processes and to a minor degree to expansion of dendrites and axons. There was also a light or moderate perivascular astrocytic swelling. In the spongy lesions as well as occasionally in non-vacuolated parts of the cerebral cortex, there were collapsed electron-dense neurons with pronounced mitochondrial alterations such as severe swelling associated with rupture of christae. Rats with a survival period of 24 h or 72 h showed several disintegrating neurons and accumulation of macrophages. This study shows that carotid infusion of hypertonic mannitol in the rat may cause pronounced neuronal changes as well as multifocal astrocytic swelling. The severity of the nerve cell changes and the presence of macrophages indicate that some of the alterations are irreversible and thus, such a procedure may not be as safe as previously suggested.Supported by grants from the Swedish Medical Research Council Projects No. 12X-03020, 12X-07123, 14X-04968, Trygg-Hansa, Bergwalls stiftelse, the Swedish Multipel Sclerosis Society and Finnish Medical Research Council 相似文献
995.
Mathias V. Melega Monica Alves Rodrigo Pessoa Cavalcanti Lira Iuri Cardoso da Silva Bruna Gil Ferreira Hermano LG. Assis Filho Fernando Rodrigo Pedreira Chaves Alexandre A.F. Martini Livia Maria Dias Freire Roberto dos Reis Carlos Eduardo Leite Arieta 《Journal of cataract and refractive surgery》2019,45(3):343-350
996.
Background: Midwives tend to leave minor perineal lacerations to heal spontaneously, and clinical experience and studies show that women can suffer from their stitched lacerations. The study purpose was to determine any differences in the healing process and experience of minor perineal lacerations when they were sutured or not sutured. Methods: Eighty term pregnant primiparas with minor perineal lacerations of grades I–II were randomized after childbirth. The experimental group was nonsutured and the control group was sutured. A follow‐up examination was performed at 2 to 3 days, 8 weeks, and 6 months after the delivery. Participants were asked about the type of discomfort, and the effect of the laceration on breastfeeding and sexual intercourse. Results: No significant differences were found in the healing process. The type of pain differed between the groups, but the amount of discomfort was the same. The sutured group had to visit the midwife more often because of discomfort from the stitches. Sixteen percent of the women in the sutured group, but none in the nonsutured group (p= 0.0385), considered that the laceration had had a negative influence on breastfeeding. Conclusions: Minor perineal lacerations can be left to heal spontaneously. The benefits for the woman include the possibility of having a choice, avoiding the discomfort of anesthesia and suturing, providing positive affects on breastfeeding. 相似文献
997.
The relationship between the bacterium Streptococcus mutans in the saliva and dental caries in children in Mozambique 总被引:1,自引:0,他引:1
Four hundred and sixty-two children, aged 10-14 years, from eight areas were examined for Streptococcus mutans in saliva and for dental caries. Strep. mutans strains from some samples were further characterized by serological and biochemical methods. Strep. mutans was identified in 98 per cent of the children and 40 per cent showed high counts. Serotypes c and d dominated among the strains. The distribution of Strep. mutans among the children varied between the eight areas but was not correlated with the difference in caries prevalence which ranged from 38 to 88 per cent. In individual children, however, there was an association between high counts of Strep. mutans and the presence of dental caries. Thus, Strep. mutans can be widely distributed and occurs in high numbers in a population with a low prevalence of caries. 相似文献
998.
Nine hundred and eighty-four breast cancer patients were interviewed regarding exogenous hormonal use. This represents a random sample of breast cancer patients in Southern Sweden referred to the Department of Oncology at Lund for treatment between 1978 and 1997 (excluding 1980 and 1981) with a 100% follow-up. Ever-use of hormone replacement therapy (HRT) prior to diagnosis was significantly associated with a longer overall survival in women with their breast cancer diagnosed at ages 45 and above, relative risk (RR) of dying 0.73 (95% confidence interval (CI) 0.62-0.87; P = 0.0005). Ever use of HRT prior to breast cancer diagnosis was significantly positively associated with overall longer survival after adjustment for T-stage, N-stage, M-stage, year of diagnosis and age at diagnosis, RR of dying 0.78 (95% CI 0.65-0.93; P = 0.006). Hormone replacement therapy use and oestrogen receptor positivity were independently significantly associated with overall longer survival, P = 0.005 and P < 0.0001, respectively, in one model. HRT use and progesterone receptor positivity were also independently significantly associated with longer overall survival, P = 0.003 and P = 0.0003, respectively, in another model. The mode of diagnosis was known in 705 women. Mammography screening was not more common among HRT users compared with never-users, where this information was available. Both mammography screening and HRT use were independently associated with longer survival, P = 0.002 and P = 0.038 respectively. 相似文献
999.