全文获取类型
收费全文 | 119193篇 |
免费 | 7396篇 |
国内免费 | 832篇 |
专业分类
耳鼻咽喉 | 1355篇 |
儿科学 | 3568篇 |
妇产科学 | 2832篇 |
基础医学 | 16523篇 |
口腔科学 | 4510篇 |
临床医学 | 9610篇 |
内科学 | 25570篇 |
皮肤病学 | 2499篇 |
神经病学 | 10549篇 |
特种医学 | 4186篇 |
外国民族医学 | 24篇 |
外科学 | 16001篇 |
综合类 | 1939篇 |
一般理论 | 54篇 |
预防医学 | 8437篇 |
眼科学 | 1789篇 |
药学 | 9472篇 |
3篇 | |
中国医学 | 781篇 |
肿瘤学 | 7719篇 |
出版年
2023年 | 638篇 |
2022年 | 1556篇 |
2021年 | 2692篇 |
2020年 | 1790篇 |
2019年 | 2417篇 |
2018年 | 2940篇 |
2017年 | 2235篇 |
2016年 | 2312篇 |
2015年 | 2707篇 |
2014年 | 3535篇 |
2013年 | 4886篇 |
2012年 | 6783篇 |
2011年 | 7175篇 |
2010年 | 4364篇 |
2009年 | 3660篇 |
2008年 | 5819篇 |
2007年 | 5910篇 |
2006年 | 5578篇 |
2005年 | 5159篇 |
2004年 | 5376篇 |
2003年 | 5138篇 |
2002年 | 5091篇 |
2001年 | 4198篇 |
2000年 | 4216篇 |
1999年 | 3398篇 |
1998年 | 1271篇 |
1997年 | 975篇 |
1996年 | 913篇 |
1995年 | 876篇 |
1994年 | 765篇 |
1993年 | 724篇 |
1992年 | 1971篇 |
1991年 | 1939篇 |
1990年 | 1666篇 |
1989年 | 1610篇 |
1988年 | 1483篇 |
1987年 | 1295篇 |
1986年 | 1274篇 |
1985年 | 1141篇 |
1984年 | 856篇 |
1983年 | 760篇 |
1982年 | 478篇 |
1981年 | 419篇 |
1979年 | 644篇 |
1978年 | 488篇 |
1975年 | 477篇 |
1974年 | 536篇 |
1973年 | 512篇 |
1972年 | 450篇 |
1971年 | 425篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
C M Kyaw C R De Araujo M R Lima E G S Gondim M M Brígido L G Giugliano 《Infection, genetics and evolution》2003,3(2):111-117
Diffusely adhering Escherichia coli (E. coli) strains (DAEC) represent a potential cause of diarrhoea in infants, and the detection of type three secretion system (TTSS) genes in DAEC would substantiate their pathogenic nature. In this work, four isolates of DAEC, recovered from stools of diarrhoeic children, were analysed by PCR, in order to detect the presence of TTSS genes. Primers targeted to the escC, escJ, escN and escV, some of the most conserved TTSS genes in enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC), were used in order to verify the occurrence of homologous genes in our DAEC isolates. By this approach, we were able to characterise DNA fragments corresponding to putative escJ and escN genes in all DAEC isolates. Furthermore, DNA fragments homologous to the escC and escV genes were also amplified from all isolates. Besides the similarity found among the DAEC esc homologues with EPEC and EHEC esc genes, the nucleotide sequence analysis of the flanking regions of the amplified DNA fragments suggests that the putative DAEC esc genes are organised in the same manner as observed in EPEC and in EHEC strains. The results described here provide strong evidence for the presence of a TTSS in the DAEC strains analysed, implicating a pathogenic nature of these isolates. 相似文献
12.
Cyanoacrylate-based glues have been reported as producing dermatitis and bronchial asthma. The paper describes the case of a patient occupationally exposed to Loctite 406, who developed irritation of the skin and mucosae of the face and late bronchial asthma. Preventive measures for subjects exposed to cyanoacrylic instant glues are discussed. 相似文献
13.
The response of single detergent treated bovine retinal pigment epithelial cells in culture to ATP was measured with an image analyser. The most pronounced contraction was produced by 1.0 mM ATP with most change taking place in the first 10 min. At 1 h the area had decreased by about 33%, perimeter 22% and maximum length 25%. By way of comparison rabbit skin fibroblasts had a decreased area of approximately 40%, perimeter 25% and maximum length 22%. Bovine aortic smooth muscle cells on the other hand decreased in area by 55%, perimeter 40% and maximum length 36%. It is hoped that this assay may be used to evaluate drugs which could counteract contractile events in proliferative vitreoretinopathy. 相似文献
14.
B. Bogin P. Smith A.B. Orden M.I. Varela Silva J. Loucky 《American journal of human biology》2002,14(6):753-761
Maya families from Guatemala migrated to the United States in record numbers from the late 1970s to the early 1990s. Births to Maya immigrant women have created a sizable number of Maya American children. The height and sitting height of 5 to 12 years children (n = 431) were measured in 1999 and 2000. Leg length was estimated and the sitting height ratio was calculated. These data were compared with a sample of Maya children living in Guatemala measured in 1998 (n = 1,347). Maya American children are currently 11.54 cm taller and 6.83 cm longer‐legged, on average, than Maya children living in Guatemala. Consequently, the Maya Americans have a significantly lower average sitting height ratio (i.e., relatively longer legs in proportion to length of the head and trunk) than do the Maya in Guatemala. These results add support to the hypothesis that both the height and body proportions of human populations are sensitive indicators of the quality of the environment for growth. Am. J. Hum. Biol. 14:753–761, 2002. © 2002 Wiley‐Liss, Inc. 相似文献
15.
4-Aminopyridine affects synaptosomal protein phosphorylation in rat hippocampal slices 总被引:2,自引:0,他引:2
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II). 相似文献
16.
L. Lupo V. De Grandi E. Ganci A. Nastri S. Ielo A. Mistretta G. Giammanco 《European journal of epidemiology》1989,5(3):400-402
A longitudinal survey (February 1984 - January 1985) on the incidence of acute diarrhea episodes in a sample of 8,164 children (aged 0–12 years) living in southeastern Sicily was carried out by means of weekly telephone interviews with doctors practising in the territory. The incidence rate was 0.479 (0.472–0.485 95% C.I.) per child per year and the frequency of episodes was significantly higher (p < 0.001) in children aged 0–4 years (0.86). Diarrhea was more frequent in industrial areas than in rural ones, and almost half (45.1%) of the total episodes had a mild course. No death from diarrhea occurred and admission to hospital was reported for 8.4% of all cases.Corresponding author. 相似文献
17.
D. Caroline Blanchard Jon K. Shepherd Antonio De Padua Carobrez Robert J. Blanchard 《Neuroscience and biobehavioral reviews》1991,15(4):461-468
Female rats consistently show a pattern of differences in defensive behaviors compared to males which parallel the effects of exposure to a nonpainful threat stimulus (cat or cat odor) in the same tests and measures. These indications of greater defensiveness for females are particularly common in situations involving potential, as opposed to actual and present, threat, a factor which probably also reflects ceiling or floor effects in situations involving very intense defensiveness. In addition, pharmacological studies indicate sex differences in the effects of selective serotonin (5-HT) receptor agonists and antagonists on defensive responding. These findings indicate that sex effects must be considered in studies of the pharmacological control of defensive behaviors, and suggest that responsivity to sex effects may be an additional criterion for the suitability of animal models of anxiety. 相似文献
18.
Is interleukin 2 a neuromodulator in the brain? 总被引:5,自引:0,他引:5
A bidirectional flow of information exists between the CNS and the neuroendocrine and immune systems, representing an important homeostatic mechanism in the body. Lymphokines and other products of immunocompetent cells seem to play a crucial role in this communication and seem to exert powerful effects on neurones in the brain. In this article, Giuseppe Nisticò and Giovambattista De Sarro describe the central effects following interleukin 2 (IL-2) microinfusion into several areas of the rat brain. The locus coeruleus seems to be the main site in the brain through which IL-2 exerts soporific effects. In addition, the possible transducing mechanisms coupling IL-2 receptor stimulation and the electroencephalogram (EEG) spectrum power responses elicited from the locus coeruleus seem to involve stimulation of specific receptors coupled to adenylate cyclase through a Gi protein. 相似文献
19.
20.