全文获取类型
收费全文 | 7661篇 |
免费 | 405篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 93篇 |
儿科学 | 317篇 |
妇产科学 | 217篇 |
基础医学 | 1116篇 |
口腔科学 | 376篇 |
临床医学 | 721篇 |
内科学 | 1462篇 |
皮肤病学 | 253篇 |
神经病学 | 729篇 |
特种医学 | 403篇 |
外科学 | 1084篇 |
综合类 | 63篇 |
一般理论 | 10篇 |
预防医学 | 404篇 |
眼科学 | 37篇 |
药学 | 410篇 |
中国医学 | 9篇 |
肿瘤学 | 372篇 |
出版年
2022年 | 49篇 |
2021年 | 96篇 |
2020年 | 69篇 |
2019年 | 77篇 |
2018年 | 108篇 |
2017年 | 96篇 |
2016年 | 110篇 |
2015年 | 128篇 |
2014年 | 157篇 |
2013年 | 235篇 |
2012年 | 340篇 |
2011年 | 337篇 |
2010年 | 221篇 |
2009年 | 210篇 |
2008年 | 320篇 |
2007年 | 333篇 |
2006年 | 307篇 |
2005年 | 321篇 |
2004年 | 273篇 |
2003年 | 265篇 |
2002年 | 302篇 |
2001年 | 270篇 |
2000年 | 228篇 |
1999年 | 212篇 |
1998年 | 104篇 |
1997年 | 102篇 |
1996年 | 94篇 |
1995年 | 87篇 |
1994年 | 80篇 |
1993年 | 90篇 |
1992年 | 121篇 |
1991年 | 107篇 |
1990年 | 118篇 |
1989年 | 127篇 |
1988年 | 114篇 |
1987年 | 131篇 |
1986年 | 115篇 |
1985年 | 101篇 |
1984年 | 80篇 |
1983年 | 76篇 |
1982年 | 58篇 |
1981年 | 57篇 |
1978年 | 62篇 |
1977年 | 58篇 |
1976年 | 73篇 |
1975年 | 49篇 |
1973年 | 55篇 |
1969年 | 49篇 |
1968年 | 48篇 |
1966年 | 51篇 |
排序方式: 共有8076条查询结果,搜索用时 15 毫秒
1.
D Gröne† R Treudler† EM de Villiers‡ R Husak† CE Orfanos† ChC Zouboulis†§ 《Journal of the European Academy of Dermatology and Venereology》2006,20(2):202-205
Cidofovir is an acyclic nucleoside phosphonate with broad-spectrum activity against DNA viruses, including human papilloma virus (HPV). However, data on the efficacy of cidofovir in an immunosuppressive setting remain contradictory. We report for the first time on the promotion of the healing of recalcitrant warts in a patient with myelodysplastic syndrome with intravenous cidofovir treatment. 相似文献
2.
3.
4.
Feeding behavior in Aplysia fasciata and A. oculifera is modified by pairing the behavior with reinforcing consequences. Successful and unsuccessful attempts to transfer food from the buccal cavity to the crop act as positive and negative reinforcers, respectively. A number of changes in feeding behavior occur as a result of pairing of feeding with the negative reinforcer: feeding responses become less effective in leading to the entry of food into the buccal cavity; when food does enter the buccal cavity, it exits sooner; swallowing responses after food entry are less likely to occur; Aplysia eventually cease responding to food. Pairing successful transfer of food into the crop with feeding behavior produces opposite effects. Behavioral change is specific to pairing, as shown by lack of change when reinforcement is explicitly unpaired with feeding behavior. Behavioral change is specific to foods with a particular taste and texture; generalization to alternate foods was not observed. In spite of cessation of feeding, animals remain aroused, as shown by low response latency to alternate foods. Memory of response change persists for at least 48 hr. 相似文献
5.
Development of cytochrome P-450-altered preneoplastic and neoplastic lesions during nitrosamine-induced hepatocarcinogenesis in the rat 总被引:3,自引:0,他引:3
The expression of four cytochrome (cyt.) P-450 isoenzymes has been studied in preneoplastic and neoplastic lesions during the course of nitrosamine-induced hepatocarcinogenesis in the female Wistar rat. Following exposure to diethylnitrosamine (50 or 100 ppm in the drinking water) for 10 days, animals were taken sequentially, and the livers were analyzed for the evolution of adenosine triphosphatase deficient focal lesions. These lesions were subdivided into different phenotypes with regard to their cyt. P-450 isoenzyme expression using serial frozen sections. Our results demonstrate that about 40% of the adenosine triphosphatase-deficient lesions show concomitant alterations in their cyt. P-450 isoenzyme contents. Of these lesions, islets which are characterized by decreased levels of at least three cyt. P-450 isoenzymes show a dramatic increase in their volumetric fraction of liver tissue with progression of time. Although only very few lesions express this phenotype, the contribution to the volumetric fraction of islet tissue raises from about 2% at 10 weeks to about 60% at 35 weeks after cessation of diethylnitrosamine treatment. By contrast, lesions which express less than two alterations in cyt. P-450 isoenzyme levels develop relatively slowly. Similar results were obtained when animals were exposed continuously to diethylnitrosamine for a period of up to 8 weeks. Following treatment of islet-bearing animals with phenobarbital, an induction of cyt. P-450 isoenzymes and NADPH-cyt. P-450-reductase was observed within preneoplastic and neoplastic lesions. This induction was most pronounced in large, expansively growing nodules, a type of lesion which displayed decreased levels of these enzymes in livers of animals not treated with phenobarbital. The elevation of the cyt. P-450 isoenzymes disappeared within 2 to 3 weeks after cessation of inducer treatment. Our results indicate that a high proportion of rapidly growing lesions has assumed a constitutive deficiency in cyt. P-450 isoenzyme expression during nitrosamine-induced hepatocarcinogenesis. This deficiency, however, is not an irreversible quality, since individual cyt. P-450 isoenzymes can be markedly induced by treatment with an enzyme inducer like phenobarbital. Thus, the observed decrease in cyt. P-450 expression during development of malignancy does not result from alterations in the cyt. P-450 encoding structural genes but may rather be related to abnormalities in the function of regulatory systems of a higher order which may play a central role in the maintenance of cell homeostasis. 相似文献
6.
7.
From 1930 to 1989 postoperative rupture of abdominal wound occurred in 0.42 per cent (n = 82) in the Department of Obstetrics and Gynaecology of the University of Rostock. 60 per cent of the patients were younger than 50 years. Patients of reduced general condition and anaemia were predisposed to this complication. We observed postoperative alterations of the respiratory tract in 13 per cent and alterations of the gastro-intestinal tract in 20 per cent which lead to increased intra-abdominal pressure. We observed postoperative wound rupture only in 8 cases after Pfannenstiel's incision, but all other times after median section, predominantly during the 7th and 12th postoperative day. All patients were treated by secondary suture, immediately. 8 patients came to death, three of them had no direct link to wound rupture. For prophylaxis the use of non-absorbable suture material, safety sutures, intraoperative blood and protein substitution and prevention of affections of the respiratory system and gastrointestinal tract are recommended. 相似文献
8.
T. Hammen F. Kerling M. Schwarz A. Stadlbauer O. Ganslandt B. Keck B. Tomandl A. Dörfler H. Stefan 《European journal of neurology》2006,13(5):482-490
Up to 30% of patients with temporal lobe epilepsy (TLE) remain without remarkable changes in MRI. In this study we investigated the role of (1)H-MR spectroscopy ((1)H-MRS) in lateralizing the affected hemisphere in the mentioned patient group. Twenty-two consecutive patients diagnosed with TLE were investigated by high resolution MRI and (1)H-MRS. We examined the incidence and diagnostic accuracy of temporal metabolite alterations determined by Linear Combination of Model Spectra (L C Model) via water reference. Metabolite values of each hemisphere of TLE patients were compared with healthy controls. Results of metabolite alterations were related to intensive video EEG focus localization. Reduction of N-acetylaspartate + N-acetylaspartyl-glutamate (tNAA) in the affected hemisphere revealed identification in six of nine patients (66%) with unilateral TLE. Group comparison revealed a significant reduction of tNAA (6.1+/-0.8*) in the involved temporal lobe compared with controls (6.67+/-0.4*, P=0.026). Choline levels were significantly increased in the affected hemisphere (1.42+/-0.17*) compared with healthy controls (1.22+/-0.17*, P=0.035). The results of our study show that (1)H-MRS is able to identify the affected hemisphere of MRI negative TLE patients and can be used as an additive tool in multimodal focus localization. 相似文献
9.
10.
On the surface of the free (receptor-unbound) form of hCG, we have previously identified 14 topographically distinct epitopes (Schwarz et al. (1986) Endocrinology 118, 189-197; Berger et al. (1990) J. Endocrinol. 125, 301-309). Here we report that only two of them, i.e. the (adjacent) beta 3 and beta 5 epitopes, can be recognized by 125iodine-labeled monoclonal antibodies when hCG was specifically bound to the rat testis hCG receptor. The exclusive accessibility of precisely these two surface epitopes indicates that hCG assumes a defined rather than a stochastic orientation in its receptor-bound state. The inaccessibility of 12 of 14 epitopes is consistent with the idea that the 341 residues long extracellular domain of the recently cloned hCG receptor (MacFarland et al. (1989) Science 245, 494-499) is the ligand binding domain. It is proposed that the extracellular domain is folded in a way that a cavity is formed large enough to accommodate hCG. Thereby, a considerable portion of the total surface of hCG is covered, as reflected by the masking of most of its epitopes. 相似文献