全文获取类型
收费全文 | 70865篇 |
免费 | 4625篇 |
国内免费 | 3058篇 |
专业分类
耳鼻咽喉 | 253篇 |
儿科学 | 1174篇 |
妇产科学 | 699篇 |
基础医学 | 6976篇 |
口腔科学 | 1412篇 |
临床医学 | 4193篇 |
内科学 | 8097篇 |
皮肤病学 | 1808篇 |
神经病学 | 6628篇 |
特种医学 | 1304篇 |
外国民族医学 | 5篇 |
外科学 | 3946篇 |
综合类 | 9229篇 |
现状与发展 | 3篇 |
预防医学 | 5121篇 |
眼科学 | 592篇 |
药学 | 17785篇 |
14篇 | |
中国医学 | 6908篇 |
肿瘤学 | 2401篇 |
出版年
2024年 | 247篇 |
2023年 | 1010篇 |
2022年 | 1721篇 |
2021年 | 2208篇 |
2020年 | 2104篇 |
2019年 | 1764篇 |
2018年 | 1708篇 |
2017年 | 1992篇 |
2016年 | 2166篇 |
2015年 | 2285篇 |
2014年 | 4098篇 |
2013年 | 4946篇 |
2012年 | 4048篇 |
2011年 | 4446篇 |
2010年 | 3356篇 |
2009年 | 3228篇 |
2008年 | 3377篇 |
2007年 | 3426篇 |
2006年 | 3009篇 |
2005年 | 2694篇 |
2004年 | 2382篇 |
2003年 | 2045篇 |
2002年 | 1699篇 |
2001年 | 1472篇 |
2000年 | 1300篇 |
1999年 | 1153篇 |
1998年 | 1097篇 |
1997年 | 1039篇 |
1996年 | 1002篇 |
1995年 | 938篇 |
1994年 | 839篇 |
1993年 | 709篇 |
1992年 | 705篇 |
1991年 | 648篇 |
1990年 | 642篇 |
1989年 | 607篇 |
1988年 | 561篇 |
1987年 | 500篇 |
1986年 | 521篇 |
1985年 | 779篇 |
1984年 | 725篇 |
1983年 | 536篇 |
1982年 | 536篇 |
1981年 | 498篇 |
1980年 | 456篇 |
1979年 | 315篇 |
1978年 | 239篇 |
1977年 | 189篇 |
1976年 | 165篇 |
1975年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
82.
83.
84.
J.K. MOHANA RAO 《Chemical biology & drug design》1987,29(2):276-281
Based on residue characteristic physical parameters, a new scoring matrix, called EMPAR, for amino acid exchanges in proteins was obtained. When comparing protein sequences for detecting homologies, the use of this matrix in place of the Dayhoff log-odds matrix yields results that reflect the topological similarities in the proteins. The use of EMPAR is equivalent to the parametric correlation coefficient approach of Ooi and his colleagues. This matrix correlates at 0.63 with the Dayhoff matrix. 相似文献
85.
The toxic effects of nitroquine-dapsone compound(NQD)in mice and dogs were studied.The therapeutic index of NQDin mice is 1911,the greatest among the 6 antimalarials tested.Thetoxic effects of NQD(50 mg/kg/day for 3 days per os)and nitro-quine in dogs were manifested by injuries on the adrenal cortexand intestinal epithelium.When folic acid(4 mg/kg/day for 4 days)or calcium leucovorinum(0.3 mg/kg/day for 4 days)were usedconcomitantly with NQD,the death rate and the incidence of dia-rrhea in the toxicated dogs were greatly reduced,the injury on theintestinal epithelium was much milder,and the goblet cells weremuch more numerous than those without treatment.The results suggestthat folic acid and calcium leucovorinum can protect the undifferen-tiated cells in the intestinal crypts from being injured by NQD. 相似文献
86.
87.
HPLC analysis of the embryo-toxic fraction of human uterinefluid, collected between the 22nd and 25th days of the menstrualcycle, revealed the presence of cholic acid at high concentrations.It is suggested that cholic acid could be responsible for theembryo-toxicity of the uterine environment, which follows thereceptive period for implantation. 相似文献
88.
Glucocorticoid effects on kainic acid-induced motor seizures and wet dog shakes in rats were investigated by adrenalectomy and dexamethasone treatment. One-day adrenalectomy attenuated kainic acid-induced wet dog shakes and seizure activity. These effects were restored by dexamethasone. Administration of dexamethasone to non-adrenalectomized rats potentiated kainic acid-induced wet dog shakes and severity of seizure activity. These results suggest that glucocorticoids may play an important role in modulating the severity of kainic acid-induced seizures and wet dog shakes. 相似文献
89.
Meg Sears C Robin Walker Richard HC van der Jagt Paul Claman 《Paediatrics & child health》2006,11(4):229-234
Pesticide regulation is examined in the context of Health Canada’s Pest Management Regulatory Agency’s assessment of the chlorophenoxy herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) for turf. 2,4-D is the most common herbicide used to kill weeds in grass.The medical literature does not uniformly indicate harms from herbicides. However, the balance of epidemiological research suggests that 2,4-D can be persuasively linked to cancers, neurological impairment and reproductive problems. These may arise from 2,4-D itself, from breakdown products or dioxin contamination, or from a combination of chemicals.Regulators rely largely on toxicology, but experiments may not replicate exposures from 2,4-D application to lawns because environmental breakdown products (eg, 2,4-dichlorophenol) may not accumulate and selected herbicides are possibly less contaminated. Dioxins are bioaccumulative chemicals that may cause cancer, harm neurological development, impair reproduction, disrupt the endocrine system and alter immune function. No dioxin analyses were submitted to the Pest Management Regulatory Agency, and the principal contaminants of 2,4-D are not among the 17 congeners covered in pesticide regulation. Independent assessment of all dioxins is needed, in tissues and in the environment.The 2,4-D assessment does not approach standards for ethics, rigour or transparency in medical research. Canada needs a stronger regulator for pesticides. Potentially toxic chemicals should not be registered when more benign solutions exist, risks are not clearly quantifiable or potential risks outweigh benefits. Until landscaping pesticides are curtailed nationally, local bylaws and Quebec’s Pesticide Code are prudent measures to protect public health. Physicians have a role in public education regarding pesticides. 相似文献
90.