全文获取类型
收费全文 | 2817214篇 |
免费 | 199398篇 |
国内免费 | 9822篇 |
专业分类
耳鼻咽喉 | 37996篇 |
儿科学 | 90366篇 |
妇产科学 | 77895篇 |
基础医学 | 395805篇 |
口腔科学 | 77317篇 |
临床医学 | 253977篇 |
内科学 | 559888篇 |
皮肤病学 | 67568篇 |
神经病学 | 230154篇 |
特种医学 | 107920篇 |
外国民族医学 | 791篇 |
外科学 | 422730篇 |
综合类 | 57663篇 |
现状与发展 | 6篇 |
一般理论 | 1020篇 |
预防医学 | 207222篇 |
眼科学 | 63314篇 |
药学 | 207397篇 |
9篇 | |
中国医学 | 7081篇 |
肿瘤学 | 160315篇 |
出版年
2021年 | 22072篇 |
2019年 | 22595篇 |
2018年 | 32324篇 |
2017年 | 24870篇 |
2016年 | 28672篇 |
2015年 | 32382篇 |
2014年 | 44432篇 |
2013年 | 65658篇 |
2012年 | 87278篇 |
2011年 | 91664篇 |
2010年 | 55363篇 |
2009年 | 53101篇 |
2008年 | 85256篇 |
2007年 | 90653篇 |
2006年 | 92031篇 |
2005年 | 87736篇 |
2004年 | 84305篇 |
2003年 | 81359篇 |
2002年 | 78396篇 |
2001年 | 142892篇 |
2000年 | 146033篇 |
1999年 | 122917篇 |
1998年 | 34527篇 |
1997年 | 30476篇 |
1996年 | 30235篇 |
1995年 | 29256篇 |
1994年 | 26794篇 |
1993年 | 24983篇 |
1992年 | 93838篇 |
1991年 | 89757篇 |
1990年 | 86615篇 |
1989年 | 83789篇 |
1988年 | 76618篇 |
1987年 | 74853篇 |
1986年 | 69938篇 |
1985年 | 66472篇 |
1984年 | 49021篇 |
1983年 | 41390篇 |
1982年 | 24125篇 |
1981年 | 21399篇 |
1979年 | 42447篇 |
1978年 | 29578篇 |
1977年 | 25220篇 |
1976年 | 23010篇 |
1975年 | 24621篇 |
1974年 | 28880篇 |
1973年 | 27359篇 |
1972年 | 25742篇 |
1971年 | 23946篇 |
1970年 | 22012篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
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
993.
994.
Protein-calorie malnutrition (PCM) impairs immune responsiveness predisposing to Candida albicans sepsis, but mechanisms are unclear. This study examined the effect of PCM on enteric-derived C. albicans intestinal translocation and the ability of in vivo interferon-gamma (IFN-gamma) to upregulate macrophage (MO) candidacidal mechanisms in PCM mice. Control (24% casein) and low protein (2.5%) diets were given for 4 weeks. Mice (n = 160) were fed C. albicans in their drinking water for 3 days and C. albicans translocation (mean colony-forming units (CFU)/g tissue +/- SEM) to the GI tract, liver, spleen, and kidney was assessed at 1 and 5 days following endotoxin challenge of 1, 5, and 10 mg/kg body wt. In a separate study (n = 100 mice), IFN-gamma (1000-10,000 U/day ip) vs saline was given for 3 days prior to harvesting peritoneal macrophages for assay of superoxide anion (O2-), percentage macrophage phagocytosis of C. albicans, and percentage killing of C. albicans. On Day 1, fungal translocation to the intestinal wall and systemic organs in the PCM group was significantly higher. On Day 5, mean CFU were significantly higher in the PCM group, indicating impaired organ clearance. Mean O2-, phagocytosis, and killing were significantly impaired in the PCM group (P less than 0.05), but IFN-gamma improved all functions. PCM significantly depressed host responses to C. albicans. IFN-gamma treatment enhanced candidacidal mechanisms, suggesting a therapeutic role in the malnourished host predisposed to C. albicans sepsis. 相似文献
995.
996.
The effect of sodium fluoride on trabecular architecture. 总被引:1,自引:0,他引:1
The effect of sodium fluoride therapy on iliac trabecular bone has been studied in 15 patients with primary osteoporosis by comparing bone biopsies taken before and after two years of treatment. A marked increase in bone volume (43%) was observed, which was attributable to an increase in trabecular thickness (46%) rather than their number. Because the trabecular bone surface, the trabecular number, the bone volume/trabecular width ratio, and the trabecular terminus number do not change significantly after fluoride treatment, we conclude that fluoride does not induce the de novo generation of trabeculae, nor does it restore trabecular connectivity despite the restoration of bone mass. These data suggest that the restoration of skeletal mass with fluoride may not lead to a comparable decrease in the risk of future fracture. 相似文献
997.
Pickled vegetables are daily food consumed in the high-risk areas for esophageal cancer in China. We analyzed the nitrosamine content of Linxian pickles by GC/TEA and found that trace amounts of six nitrosamines (NDMA, NDEA, NMBA, NMAMBA, NDPA, NPYR) were present, with the highest concentrations being NDMA and NDEA (1.7 and 1.9 micrograms/kg wet weight respectively). The average level of nitrosamine precursors, such as nitrate (111.22 mg/L), nitrite (0.152 mg/L) and secondary amines (4.223 mg/L), in pickled vegetables were determined, and their pH values ranged from 3 to 5. 相似文献
998.
N M Alpert W C Barker A Gelman S Weise M Senda J A Correia 《Journal of cerebral blood flow and metabolism》1991,11(2):A26-A30
The limits of quantitation with positron emission tomography (PET) are examined with respect to the noise propagation resulting from radioactive decay and other sources of random error. Theoretical methods for evaluating the statistical error have been devised but seldom applied to experimental data obtained on human subjects. This paper extends the analysis in several ways: (1) A Monte Carlo method is described for tracking the propagation of statistical error through the analysis of in vivo measurements; (2) Experimental data, obtained in phantoms, validating the Monte Carlo method and other methods are presented; (3) A difference in activation paradigm, performed on regional CBF (rCBF) data from five human subjects, was analyzed on 1.6-cm diameter regions of interest to determine the mean fractional statistical error in PET tissue concentration and in rCBF before and after stereotactic transformation; and (4) A linear statistical model and calculations of the various statistical errors were used to estimate the magnitude of the subject-specific fluctuations under various conditions. In this specific example, the root mean squared (RMS) noise in flow measurements was about three times higher than the RMS noise in the concentration measurements. In addition, the total random error was almost equally partitioned between statistical error and random fluctuations due to all other sources. 相似文献
999.
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
1000.
J Verlooy J Van Reempts M Haseldonckx M Borgers P Selosse 《Acta neurologica Belgica》1991,91(3):151-157
A new experimental model is described which can be used as an alternative to study the effects of subarachnoid hemorrhage (SAH) in rats. Vasospasm of the basilar artery is induced photochemically after transpalatal illumination of intracisternally injected rose bengal in two different rat strains. Singlet oxygen, generated in the subarachnoid space, elicits vasospasm which has been demonstrated angiographically at 90 min and 24 h after photosensitisation. Sprague Dawley rats responded better than Wistar rats. Dilution of rose bengal in water was more vasospastic than dilution of rose bengal in artificial CSF. Since the action of singlet oxygen is similar to that of free radicals, this experiment gives an argument for the hypothesis that free radicals play a leading role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage. 相似文献