全文获取类型
收费全文 | 2141991篇 |
免费 | 166079篇 |
国内免费 | 4193篇 |
专业分类
耳鼻咽喉 | 29443篇 |
儿科学 | 68975篇 |
妇产科学 | 59836篇 |
基础医学 | 315775篇 |
口腔科学 | 61953篇 |
临床医学 | 189810篇 |
内科学 | 410942篇 |
皮肤病学 | 47592篇 |
神经病学 | 167856篇 |
特种医学 | 85911篇 |
外国民族医学 | 529篇 |
外科学 | 322824篇 |
综合类 | 47914篇 |
现状与发展 | 8篇 |
一般理论 | 714篇 |
预防医学 | 163300篇 |
眼科学 | 49971篇 |
药学 | 165088篇 |
3篇 | |
中国医学 | 5298篇 |
肿瘤学 | 118521篇 |
出版年
2018年 | 22389篇 |
2017年 | 17270篇 |
2016年 | 19847篇 |
2015年 | 23613篇 |
2014年 | 31634篇 |
2013年 | 46437篇 |
2012年 | 63854篇 |
2011年 | 67171篇 |
2010年 | 39498篇 |
2009年 | 36936篇 |
2008年 | 61945篇 |
2007年 | 64936篇 |
2006年 | 65107篇 |
2005年 | 62894篇 |
2004年 | 61376篇 |
2003年 | 58042篇 |
2002年 | 56420篇 |
2001年 | 96155篇 |
2000年 | 99270篇 |
1999年 | 83715篇 |
1998年 | 22986篇 |
1997年 | 20650篇 |
1996年 | 20791篇 |
1995年 | 20073篇 |
1994年 | 18824篇 |
1993年 | 17786篇 |
1992年 | 67981篇 |
1991年 | 67243篇 |
1990年 | 66020篇 |
1989年 | 63786篇 |
1988年 | 59228篇 |
1987年 | 58361篇 |
1986年 | 55411篇 |
1985年 | 53539篇 |
1984年 | 39888篇 |
1983年 | 34303篇 |
1982年 | 19912篇 |
1981年 | 18026篇 |
1979年 | 38220篇 |
1978年 | 26824篇 |
1977年 | 22678篇 |
1976年 | 21500篇 |
1975年 | 23095篇 |
1974年 | 28048篇 |
1973年 | 26791篇 |
1972年 | 24929篇 |
1971年 | 23535篇 |
1970年 | 21702篇 |
1969年 | 20448篇 |
1968年 | 18828篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Summary In cases where a reconstruction of defects in the larynx, oral cavity, the pharynx or in the ear region has been performed using skin flaps, a temporary fistula is formed at the point of entry.This fistula can be closed later after the flap has taken and the flap pedicle dissected.We would like to demonstrate with some examples that with the use of deepithelisation it is possible to achieve a primary wound closure. This way no temporary fistula results and additional surgery is avoided in many cases.Furthermore flap deepithelisation offers a way to bring good vascularised tissue under the skin and cover subcutaneous defects, for example those after radiotherapy.
Die Veröffentlichung des Manuskripts soll in Laryngol Rhinol Otol (Stuttg) erfolgen 相似文献
Die Veröffentlichung des Manuskripts soll in Laryngol Rhinol Otol (Stuttg) erfolgen 相似文献
992.
G B Hopkinson D A Woodward N Prasad B R Bullen 《Annals of the Royal College of Surgeons of England》1983,65(5):323-324
The presence of accessory channels between the liver and extrahepatic bile ducts has long been recognised by anatomists and the division of such ducts may be a cause of bile leakage following cholecystectomy. However, visualisation of accessory bile ducts at operation is difficult as they are often small and sometimes less than 1 mm in diameter. Cholangiography has been used to help in the identification of accessory ducts in 50 patients included in a prospective trial. X-rays were taken after dissection of the gall bladder from its bed and extravasation of contrast was seen on five occasions (10%) suggesting leakage from divided accessory ducts. The identification of damage to accessory bile ducts in 10% of patients suggests that this may occur more frequently than previously supposed. 相似文献
993.
994.
Anal dilatation is still used in the treatment of anal fissure and haemorrhoids. Using anorectal physiology and anal endosonography we have studied 12 men presenting with faecal incontinence following anal dilatation. Resting anal pressures were low, pudendal nerve latencies were normal; 11 men had a disrupted internal anal sphincter and in ten this was extensively fragmented. Three also had defects of the external anal sphincter. These findings demonstrate for the first time the nature of the structural injury which may be caused by anal dilatation. 相似文献
995.
996.
Deep venous thrombosis and pulmonary embolism 总被引:2,自引:0,他引:2
All surgical patients are at risk for the development of deep venous thrombosis and subsequent pulmonary embolism or postphlebitic syndrome. The evolution of ultrasonographic imaging has increased the awareness of prevention, diagnosis, and treatment of deep venous thrombosis. Duplex imaging and Doppler color flow imaging have made the diagnosis of deep venous thrombosis relatively simple, painless, inexpensive, and definitive. These procedures have gained acceptance by both patients and physicians. Several risk factors have been identified that increase the chance of the development of deep venous thrombosis. These factors include a history of deep venous thrombosis, presence of a malignant process, increasing age, cigarette smoking, obesity, prolonged bed rest, and general anesthesia. The greater the number of risk factors, the more aggressive prophylaxis should be. Means of prophylaxis have improved, and surgeons now generally agree that some form of prophylaxis is required. Heparin and intermittent compression devices appear to be equally effective in preventing deep venous thrombosis. The addition of venous monitoring in high-risk patients permits immediate identification of the presence of deep venous thrombosis. During the last decade, the treatment of patients with deep venous thrombosis has changed little. Heparin followed by warfarin remains the treatment of choice. A small group of patients receive fibrinolytic therapy for deep venous thrombosis. Although the incidence of postoperative deep venous thrombosis has decreased during the last decade, it remains a significant complication. 相似文献
997.
NPY hyperinnervation in Hirschsprung's disease: both adrenergic and nonadrenergic fibers contribute.
L T Larsson G Malmfors E Ekblad R Ekman F Sundler 《Journal of pediatric surgery》1991,26(10):1207-1214
In Hirschsprung's disease, the aganglionic bowel is characterized by an absence of ganglion cells and an increased number of adrenergic and presumed cholinergic nerve fibers. In addition, a severe derangement of peptide-containing nerve fibers is encountered including a hyperinnervation of neuropeptide Y (NPY)-containing fibers. Using immunochemical and immunocytochemical methods, we examined the nature of the NPY-containing nerve fibers contributing to the hyperinnervation. The concentration of NPY was markedly increased in the aganglionic segment. Coexistence of NPY, vasoactive intestinal peptide (VIP), and the adrenergic enzyme tyrosine hydroxylase (TH) showed small populations of nerve fibers containing NPY/TH, NPY/VIP, or TH alone in ganglionic intestine. Numerous nerve fibers stored VIP but lacked NPY. These fibers did not contain TH, indicating that all VIP-containing fibers are nonadrenergic. In the aganglionic intestine there was a marked increase in the number of nerve fibers storing NPY/TH and NPY/VIP, whereas the fibers storing VIP alone were reduced in number. A small number of nerve fibers storing NPY alone occurred in the hypertrophic nerve bundles. NPY/VIP-containing nerve fibers were particularly numerous in the mucosa in aganglionic intestine, which may be of interest in the diagnosis of Hirschsprung's disease allowing the use of mucosal biopsy specimens. Thus, the proliferating NPY-containing nerve fibers in the aganglionic intestine seem to comprise three different populations, one adrenergic and two nonadrenergic, one of which contains in addition VIP. 相似文献
998.
R B Resnick E Resnick M Galanter 《Progress in neuro-psychopharmacology & biological psychiatry》1991,15(4):531-538
1. A 26-32 month follow-up of 16 heroin-dependent subjects who entered a pilot trial of treatment with buprenorphine (a mixed agonist/antagonist) suggests that positive response to treatment may identify a subgroup of untreated addicts whose levels of psychosocial functioning are intermediate between those for whom methadone (a pure agonist) or naltrexone (a pure antagonist) would be indicated. 2. Buprenorphine's pharmacologic profile provides a missing link in available modalities for opiate dependence treatment, making it acceptable for many addicts who will not accept methadone maintenance treatment, join a residential therapeutic community, or be successful on naltrexone treatment. 3. Eight of the 16 ss were abstinent from heroin while receiving 0.6-3.9 mg/day buprenorphine and counseling. Responders (mean age 34 yrs) had been heroin dependent for a mean of 9.5 years (range 6-17 yrs), all were self-supporting, 4 lived with a non-addicted spouse, 5 had no prior treatment for addiction and 3 had prior naltrexone treatment, but had discontinued it and relapsed. Non-responders (mean age 30 yrs) had been heroin dependent for a mean of 7.4 yrs (range 2-19 yrs), 7 had no regular employment, all were single and 7 had no prior treatment for addiction. 4. Levels of psychosocial functioning (work, home, leisure) and global assessments of functioning were significantly higher for buprenorphine responders than non-responders (p less than .001 and p less than .01 respectively). 5. A new formulation of buprenorphine needs to be developed for addiction treatment, ideally consisting of 0.5 mg and 2.0 mg sublingual tablets. 相似文献
999.
An investigation of the occurrence of multiple sclerosis (MS) was undertaken in the City of Galion, Ohio, USA, because of a report of an increased number of cases. As of June 1, 1987, there were 18 living cases of MS in Galion and Polk Township, for a prevalence rate of 112 cases per 100,000 population. The expected rate is approximately 65-170 cases per 100,000. In a case-control study, residents of Galion or Polk Township who had MS were compared to residents who did not have MS. The controls were matched to the cases on age and sex and had lived in Galion for at least as long as their matched case. The cases and controls did not differ in the distribution of their present or past Galion addresses, occupational histories or workplace exposures. Cases were more likely to have graduated from high school and college than controls. Cases were more likely than controls to report a history of allergies, to recall two or more relatives who had neurologic diseases that began before their first MS symptoms, to report owning a cat that died of unexplained causes and to recall having received oral polio vaccine. Cases and controls had similar levels of antibodies to measles, chickenpox, cytomegalovirus and the human T-cell lymphotrophic virus I. 相似文献
1000.
Dopamine differentially regulates dynorphin, substance P, and enkephalin expression in striatal neurons: in situ hybridization histochemical analysis. 总被引:14,自引:0,他引:14
Dopamine regulation of the levels of dynorphin, enkephalin, and substance P messenger RNAs in rat striatal neurons was analyzed with in situ hybridization histochemistry (ISHH). Relative levels of peptide mRNA expression in the patch and matrix compartments of the dorsolateral striatum were compared among control rats, rats treated for 10 d with apomorphine, rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal dopaminergic system, and rats with nigrostriatal dopaminergic lesions followed 2 weeks later by 10 d of apomorphine treatment. Image analysis of ISHH labeling demonstrated that the number of neurons expressing each peptide mRNA remained constant, whereas the relative level of peptide mRNA per neuron changed significantly, depending on the experimental treatment. Dynorphin mRNA expression increased following chronic apomorphine treatment: striatal patch neurons increased to an average of 100% above control values, whereas striatal matrix neurons showed only a 25% increase. Dynorphin mRNA expression decreased following 6-OHDA lesions: patch neurons showed an average 75% reduction in expression, whereas matrix neurons showed no significant change. In animals with 6-OHDA lesions followed by apomorphine treatment, both patch and matrix neurons showed an average increase in dynorphin expression of 300% above control levels. Changes in dynorphin mRNA levels with these treatments were matched by qualitative changes in dynorphin immunoreactivity both in the striatum and in striatonigral terminals in the substantia nigra. Neither substance P nor enkephalin mRNA levels showed a significant difference between the striatal patch and matrix compartments in any experimental condition (in the dorsolateral striatum). Substance P mRNA expression was increased an average of 50% after 10 d of apomorphine treatment and showed an average decrease of 75% following 6-OHDA lesions of the mesostriatal system. There was no significant change in the expression of substance P mRNA in striatal neurons compared to control values in rats with combined 6-OHDA lesion and apomorphine treatment. Enkephalin mRNA expression was not significantly altered by chronic apomorphine treatment but showed an average increase per cell of some 130% above control levels following 6-OHDA-induced lesions of the mesostriatal system. In animals with a 6-OHDA lesion and apomorphine treatment, enkephalin mRNA was also elevated but not significantly above the levels produced by the lesions alone. These data show that the expression of dynorphin, enkephalin, and substance P is differentially regulated by the mesostriatal dopaminergic system and, further, suggests that the mechanisms by which this regulation occurs may be different for the 3 peptide families. 相似文献