全文获取类型
收费全文 | 31836篇 |
免费 | 2842篇 |
国内免费 | 1234篇 |
专业分类
耳鼻咽喉 | 119篇 |
儿科学 | 166篇 |
妇产科学 | 189篇 |
基础医学 | 2289篇 |
口腔科学 | 763篇 |
临床医学 | 3573篇 |
内科学 | 1778篇 |
皮肤病学 | 242篇 |
神经病学 | 753篇 |
特种医学 | 761篇 |
外科学 | 1834篇 |
综合类 | 7322篇 |
现状与发展 | 2篇 |
预防医学 | 3871篇 |
眼科学 | 274篇 |
药学 | 6056篇 |
183篇 | |
中国医学 | 5242篇 |
肿瘤学 | 495篇 |
出版年
2024年 | 204篇 |
2023年 | 490篇 |
2022年 | 1304篇 |
2021年 | 1550篇 |
2020年 | 1317篇 |
2019年 | 805篇 |
2018年 | 721篇 |
2017年 | 1020篇 |
2016年 | 1128篇 |
2015年 | 1159篇 |
2014年 | 2266篇 |
2013年 | 2270篇 |
2012年 | 2330篇 |
2011年 | 2413篇 |
2010年 | 1841篇 |
2009年 | 1475篇 |
2008年 | 1519篇 |
2007年 | 1754篇 |
2006年 | 1325篇 |
2005年 | 1134篇 |
2004年 | 965篇 |
2003年 | 773篇 |
2002年 | 665篇 |
2001年 | 594篇 |
2000年 | 514篇 |
1999年 | 474篇 |
1998年 | 393篇 |
1997年 | 336篇 |
1996年 | 336篇 |
1995年 | 321篇 |
1994年 | 300篇 |
1993年 | 286篇 |
1992年 | 249篇 |
1991年 | 221篇 |
1990年 | 195篇 |
1989年 | 181篇 |
1988年 | 170篇 |
1987年 | 151篇 |
1986年 | 143篇 |
1985年 | 151篇 |
1984年 | 89篇 |
1983年 | 54篇 |
1982年 | 93篇 |
1981年 | 45篇 |
1980年 | 35篇 |
1979年 | 30篇 |
1978年 | 29篇 |
1977年 | 20篇 |
1976年 | 24篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Segmentation of Bacteria Image Based on Level Set Method 总被引:1,自引:0,他引:1
In biology ferment engineering, accurate statistics of the quantity of bacteria is one of the most important subjects. In this paper, the quantity of bacteria which was observed traditionally manuauy can be detected automatically. Image acquisition and processing system is designed to accomplish image preprocessing, image segmentation and statistics of the quantity of bacteria. Segmentation of bacteria images is successfully realized by means of a region-based level set method and then the quantity of bacteria is computed precisely, which plays an important role in optimizing the growth conditions of bacteria. 相似文献
52.
Tomás González-Hernández Miguel Conde-Sendín Gundela Meyer 《Anatomy and embryology》1992,186(3):245-250
Summary We have studied the laminar distribution of reduced nicotinamide dinucleotide phosphate diaphorase (NADPH-d) activity and the morphology of positive neurons in the superior colliculus (SC) and the underlying periaqueductal gray (PAG) of the rat. The morphology of NADPH-d-positive neurons has been compared to that of Golgi-impregnated cells. The highest activity occurs in the stratum zonale and stratum griseum superficiale, contrasting with the pale neuropil in the stratum opticum, where only a few positive neurons are found. In the stratum griseum intermedium positive neurons are grouped in patches separated by narrow, NADPH-d-negative bands. In the deeper layers, the neuropil is NADPH-d-negative, and few neurons show enzymatic activity. In contrast, numerous neurons in the dorsolateral part of the PAG are intensely positive. They are continuous with the positive neurons in the stratum album profundum, with no clear border between the two centers. In both SC and PAG, only small and medium sized neurons are NADPH-d-positive. In comparison with Golgi material, all types of small neurons in the superficial layers show NADPH-d activity; NADPH-d histochemistry, however, does not visualize the characteristic dendritic appendages of these neurons. The large neurons of the SC and PAG, probably representing the long-projecting neurons of these centers, do not contain the enzyme. 相似文献
53.
J. Azami J. R. Fozard A. A. Round D. I. Wallis 《Naunyn-Schmiedeberg's archives of pharmacology》1985,328(4):423-429
Summary MDL 72222 (1H,3,5H-tropan-3-yl-3,5-dichlorobenzoate) is a novel compound with potent and selective blocking actions at certain excitatory 5-hydroxytryptamine (5-HT) receptors on mammalian peripheral neurones. In the present study, the sucrose-gap technique has been used to record depolarizing responses to 5-HT from the cells of the rabbit nodose and superior cervical ganglia and to investigate the potency and selectivity of MDL 72222 as an antagonist of these responses.On nodose ganglia, responses to 5-HT were inhibited surmountably by MDL 72222 at concentrations up to 100 nmol/l. The threshold for antagonism was 2–10 nmol/l and the apparent pA2 value (Schild 1947) was 7.7±0.2,n=10. Blockade was selective since responses to GABA and noradrenaline were unaffected by MDL 72222, 100 nmol/l. With concentrations of MDL 7222 higher than 100 nmol/l, antagonism was concentration-related but not in a manner consistent with simple competitive antagonism and even a concentration of 1 mol/l failed to abolish the response to 5-HT.The results from the superior cervical ganglion were essentially similar to those obtained from the nodose ganglion. The threshold concentration of MDL 72222 for inhibition of 5-HT was 1–10 nmol/l and blockade was selective in that depolarizing responses to dimethylphenylpiperazinium (DMPP) was unaffected by a concentration of MDL 72222 of 1 mol/l.The data provide direct evidence that MDL 72222 is a potent and selective antagonist of the receptors for 5-HT which mediate depolarizing responses in vagal primary afferent cell bodies and in sympathetic ganglion cells. 相似文献
54.
BALB/cJ and BALB/cByJ mice are homozygous for the autosomal gene "hippocampal lamination defect" (provisional gene symbol: Hld) which produces an abnormality in the lamination of the pyramidal cell layer of area CA3c of the hippocampus such that early-generated neurons are superficial and late-generated neurons are deep. Other inbred strains of mice are wild-type (+/+) at the Hld locus and do not have this inversion in cell position in area CA3c. The Golgi method was used to analyze the dendritic arbors of the abnormally positioned pyramidal cells and to compare the distribution of dendritic excrescences (i.e., the termination sites of the mossy fibers) in +/+ and Hld/Hld mice. It was found that in +/+ mice the late-generated pyramidal cells (whose cell bodies are positioned just below the suprapyramidal mossy fiber layer) have one set of dendritic excrescences on their apical dendrites as they extend through the suprapyramidal mossy fiber layer and a second set on their basal dendrites as they pass through the infrapyramidal mossy fiber layer. In contrast, in Hld/Hld mice the late-generated pyramidal cells (whose cell bodies are abnormally positioned just below the intrapyramidal mossy fiber layer) have two sets of dendritic excrescences on their apical dendrites, as they pass through the intrapyramidal and suprapyramidal mossy fiber layers, and none on their basal dendrites. In addition, in the vicinity of the apparent point of contact of the intrapyramidal mossy fibers, the apical dendrites of some of the abnormally positioned pyramidal cells have several fine-caliber branches.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
55.
56.
57.
目的:应用微乳液反应法制备磺胺嘧啶银均匀微晶,均匀制得的微晶的粒径大小约为2~4um,均匀微晶的结晶性好,纯度高。用均匀设计方法优化条件,制备的均匀的微晶平均粒径大小为2.09um,实验结果达到预测结果要求。结论:用微乳液反应法能获得磺胺嘧啶银均匀微晶。 相似文献
58.
59.
《中医科学杂志(英文)》2023,10(1):3-9
Inflammation-mediated carcinogenesis develops in the context of chronic inflammation and is a significant cause of cancer within the digestive system. In the chronic inflammation microenvironment, the metabolic activity of tissue cells undergoes extensive changes, which interfere with the normal function of immune cells. Dysregulation of cell metabolism and immune function has been identified as a key factor contributing to inflammation-mediated carcinogenesis within the major digestive organs, such as the stomach, liver, and colorectum. This metabolic–immune imbalance also corresponds to traditional Chinese medicine (TCM) theories of “yin-yang disharmony” and “disharmony between Ying-nutrients and Wei-defense.” The metabolic–immune imbalance has also been regarded as the key factor supporting “treatment of different diseases with the same method,” in which the same approach is adopted in the treatment of different conditions. In the TCM treatment process, it is necessary to first identify TCM patterns and then apply the corresponding TCM to correct the dysregulated metabolic and immune function, thereby blocking the progression from inflammation to malignancy. Our study findings deepen the TCM understanding of metabolic–immune dysregulation and the relationship between metabolic–immune dysregulation, pattern identification, and treatment method. They also provide new insights for the treatment of inflammation-mediated carcinogenesis in major digestive organs and help us further explore the scientific connotation of the TCM strategy of “treating different diseases with the same method. 相似文献
60.