全文获取类型
收费全文 | 139914篇 |
免费 | 10211篇 |
国内免费 | 281篇 |
专业分类
耳鼻咽喉 | 1294篇 |
儿科学 | 4072篇 |
妇产科学 | 3050篇 |
基础医学 | 21878篇 |
口腔科学 | 3728篇 |
临床医学 | 12147篇 |
内科学 | 28235篇 |
皮肤病学 | 2375篇 |
神经病学 | 13520篇 |
特种医学 | 5890篇 |
外国民族医学 | 16篇 |
外科学 | 17187篇 |
综合类 | 783篇 |
现状与发展 | 1篇 |
一般理论 | 112篇 |
预防医学 | 15681篇 |
眼科学 | 2118篇 |
药学 | 8321篇 |
中国医学 | 251篇 |
肿瘤学 | 9747篇 |
出版年
2023年 | 594篇 |
2022年 | 1007篇 |
2021年 | 2146篇 |
2020年 | 1550篇 |
2019年 | 2254篇 |
2018年 | 2832篇 |
2017年 | 2444篇 |
2016年 | 2622篇 |
2015年 | 2939篇 |
2014年 | 4008篇 |
2013年 | 5325篇 |
2012年 | 8062篇 |
2011年 | 8170篇 |
2010年 | 4270篇 |
2009年 | 4490篇 |
2008年 | 7227篇 |
2007年 | 7424篇 |
2006年 | 7175篇 |
2005年 | 6785篇 |
2004年 | 5811篇 |
2003年 | 5502篇 |
2002年 | 5036篇 |
2001年 | 4898篇 |
2000年 | 4854篇 |
1999年 | 4349篇 |
1998年 | 1856篇 |
1997年 | 1540篇 |
1996年 | 1589篇 |
1995年 | 1317篇 |
1994年 | 1245篇 |
1993年 | 1114篇 |
1992年 | 2969篇 |
1991年 | 2726篇 |
1990年 | 2565篇 |
1989年 | 2410篇 |
1988年 | 2212篇 |
1987年 | 1932篇 |
1986年 | 1847篇 |
1985年 | 1763篇 |
1984年 | 1280篇 |
1983年 | 1110篇 |
1982年 | 600篇 |
1981年 | 546篇 |
1980年 | 459篇 |
1979年 | 969篇 |
1978年 | 608篇 |
1977年 | 524篇 |
1974年 | 523篇 |
1973年 | 492篇 |
1972年 | 444篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Williamson Kathleen A.; Hever Ann M.; Rainger Joe; Rogers R. Curtis; Magee Alex; Fiedler Zdenek; Keng Wee Teik; Sharkey Freddie H.; McGill Niolette; Hill Clare J.; Schneider Adele; Messina Mario; Turnpenny Peter D.; Fantes Judy A.; van Heyningen Veronica; FitzPatrick David R. 《Human molecular genetics》2006,15(12):2030
Table 1 相似文献
32.
Marieke Peeters Ludo Verhoeven Jan de Moor Hans van Balkom 《Research in developmental disabilities》2009,30(4):712-726
The goal of this longitudinal study was to investigate the precursors of early reading development in 52 children with cerebral palsy at kindergarten level in comparison to 65 children without disabilities. Word Decoding was measured to investigate early reading skills, while Phonological Awareness, Phonological Short-term Memory (STM), Speech Perception, Speech Production and Nonverbal Reasoning were considered reading precursors. Children with cerebral palsy lag behind on all reading precursors at the beginning of the second year of kindergarten. For the children without disabilities, early reading skills in Grade 1 were best predicted by Phonological Awareness and Phonological STM while Speech Production was the most important predictor of early reading success for the children with cerebral palsy, followed by Phonological Awareness and Speech Perception. Furthermore, for children with cerebral palsy, Speech Production appears to dominate reading development, as Speech Production measured at the beginning of the second year of kindergarten was strongly predictive of all other reading precursors measured at the end of the second year of kindergarten. The results of this study reveal that children with cerebral palsy with additional speech impairments are at risk for limited literacy development. Clinical implications are discussed. 相似文献
33.
34.
35.
36.
B J Braakhuis D A Laarman J J Nauta M van Walsum G A van Dongen G B Snow 《Archives of otolaryngology--head & neck surgery》1989,115(9):1076-1078
Tumor material from 91 patients with squamous cell carcinoma of the head and neck was transplanted subcutaneously in athymic nude mice. In the first (man to mouse) passage, the calculated mean probability of tumor take in a single mouse was 11%. The probability of growth in the first passage was significantly better for moderately and poorly differentiated tumors than for well-differentiated tumors. Also, the implantation of lymph node material resulted in a significantly better tumor take rate than material taken from a primary tumor. Transplantability was not dependent on the following characteristics: localization, T or N stage of the tumor, or the sex of the patients. Once growth was established, all variables studied had no influence on the probability of growth in the subsequent mouse passages. A relationship between tumor growth in nude mice and patient prognosis could not be found. When transplanting head and neck squamous cell carcinoma in nude mice, it has to be recognized that some tumor characteristics will influence the success of tumor growth. 相似文献
37.
T. Saarne L. Kaiser H. Grönlund O. Rasool G. Gafvelin M. van Hage-Hamsten 《Clinical and experimental allergy》2005,35(5):657-663
BACKGROUND: Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy. OBJECTIVE: The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen. METHODS: The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay. RESULTS: Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400-900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1. CONCLUSION: By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients. 相似文献
38.
Evidence that dopamine in the nucleus accumbens is involved in the ability of rats to switch to cue-directed behaviours. 总被引:2,自引:0,他引:2
R van den Bos G A Charria Ortiz A C Bergmans A R Cools 《Behavioural brain research》1991,42(1):107-114
Recently we have reported that injections of d-amphetamine into the nucleus accumbens enhanced the number of switches to cue-directed behaviours without an effect on the number of switches to non-cue-directed behaviours in a swimming test. In the present study we investigated to what extent this effect is mediated via the dopaminergic system in the nucleus accumbens. For that purpose drugs selective for D1- and D2-receptors were studied in this swimming test. It was found that the selective D2-agonist LY 171 555 (50 ng/0.5 microliters) enhanced the number of different cue-directed behaviours. The selective D2-antagonist raclopride (50 ng/0.5 microliters) decreased it. Furthermore an ineffective dose of raclopride attenuated the effect of LY 171 555. Both the selective D1-antagonist SCH 23390 (400 ng/0.5 microliters) and the selective D1-agonist SKF 38393 (50-400 ng/0.5 microliters) decreased the number of different cue-directed behaviours. The effect induced by SCH 23390 could not be blocked by SKF 38393. Similarly the effect induced by SKF could not be attenuated by SCH 23390. These data point to a role for dopamine D2-receptors in the ability to switch to cue-directed behaviours. The present findings do not yet allow the conclusion that D1-receptors are involved. 相似文献
39.
B Sarmento D C Ferreira L Jorgensen M van de Weert 《European journal of pharmaceutics and biopharmaceutics》2007,65(1):10-17
The aim of the present study was to probe the structural integrity of insulin after being entrapped into chitosan/alginate nanoparticles produced by ionotropic polyelectrolyte pre-gelation. By manipulating the alginate:chitosan mass ratio and the pH during nanoparticle production, desired nanoparticles with a mean size of 850 (+/-88)nm and insulin association efficiency of 81 (+/-2)% were obtained. Insulin secondary structure was assessed by Fourier transform infrared (FTIR) and circular dichroism (CD) after entrapment into nanoparticles and after release from the particles under gastrointestinal simulated conditions. FTIR second-derivative spectra and area-overlap compared to an insulin standard confirmed that no significant conformational changes of insulin occurred in terms of alpha-helix and beta-sheet content. Far-UV-CD spectra corroborated the preservation of insulin structure during the nanoparticle production procedure. The presented nanoparticulate system is a promising carrier for insulin oral delivery since it preserves insulin structure and therefore also, potentially, its bioactivity. 相似文献
40.