全文获取类型
收费全文 | 71043篇 |
免费 | 4442篇 |
国内免费 | 3064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 | 4194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 | 9230篇 |
现状与发展 | 3篇 |
预防医学 | 5121篇 |
眼科学 | 592篇 |
药学 | 17784篇 |
16篇 | |
中国医学 | 6906篇 |
肿瘤学 | 2401篇 |
出版年
2024年 | 247篇 |
2023年 | 1010篇 |
2022年 | 1719篇 |
2021年 | 2210篇 |
2020年 | 2104篇 |
2019年 | 1765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
31.
32.
33.
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
34.
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
35.
36.
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
37.
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
38.
39.
Francisco Jose Martinez-Guijarro Eduardo Soriano Jose Antonio del Rio Carlos Lopez-Garcia 《Brain research》1991,547(2)
An antibody against the calcium binding protein parvalbumin selectively labels a set of neurons in the cerebral cortex of lizards. Golgi-like immunostained bipolar, multipolar and pyramid-like neurons appear mainly located in the inner plexiform layers. Parvalbumin-immunoreactive (PARV-IR) puncta are concentrated in the cell layer of the dorsal and dorsomedial cortices showing a basket-like distribution. The morphology and distribution of PARV-IR neurons and puncta overlap GABA-immunostaining in the cerebral cortex of lizards. Thus, it is likely that PARV-IR neurons are a subset of the cortical GABAergic neurons of lizards. 相似文献
40.
S. Vemuri 《Chemical biology & drug design》2005,65(4):433-439
Abstract: Precise determination of the peptide content in drug substance samples depends highly upon the particular peptide compound and methodology used. Four independent methods were evaluated and compared to determine which would produce the best experimental precision for analysis of thymalfasin (thymosin α‐1). Four different methods were evaluated including elemental analysis (CHN), quantitative amino acid analysis (AAA), high‐performance liquid chromatography (HPLC), and Kjeldahl. This study demonstrates that the AAA method is highly variable in one laboratory while quite precise in another laboratory. Similarly, HPLC results depended on the laboratory conducting the study with more precise values obtained under cGMP. On the contrary, the CHN method yielded highly precise [i.e. <2% coefficient of variation (CV)] values. As precise knowledge of protein content is fundamental for the compounding of final pharmaceutical product of a specific potency, the CHN analysis is recommended for peptide content determination of the drug substance thymalfasin. 相似文献