全文获取类型
收费全文 | 16182篇 |
免费 | 1257篇 |
国内免费 | 41篇 |
专业分类
耳鼻咽喉 | 104篇 |
儿科学 | 449篇 |
妇产科学 | 192篇 |
基础医学 | 2131篇 |
口腔科学 | 310篇 |
临床医学 | 1690篇 |
内科学 | 3037篇 |
皮肤病学 | 160篇 |
神经病学 | 1639篇 |
特种医学 | 725篇 |
外国民族医学 | 1篇 |
外科学 | 2225篇 |
综合类 | 221篇 |
一般理论 | 33篇 |
预防医学 | 1929篇 |
眼科学 | 247篇 |
药学 | 1160篇 |
中国医学 | 23篇 |
肿瘤学 | 1204篇 |
出版年
2023年 | 147篇 |
2022年 | 237篇 |
2021年 | 514篇 |
2020年 | 312篇 |
2019年 | 433篇 |
2018年 | 493篇 |
2017年 | 388篇 |
2016年 | 432篇 |
2015年 | 503篇 |
2014年 | 610篇 |
2013年 | 853篇 |
2012年 | 1254篇 |
2011年 | 1210篇 |
2010年 | 744篇 |
2009年 | 630篇 |
2008年 | 1088篇 |
2007年 | 1052篇 |
2006年 | 994篇 |
2005年 | 958篇 |
2004年 | 886篇 |
2003年 | 814篇 |
2002年 | 693篇 |
2001年 | 194篇 |
2000年 | 137篇 |
1999年 | 146篇 |
1998年 | 150篇 |
1997年 | 116篇 |
1996年 | 94篇 |
1995年 | 88篇 |
1994年 | 81篇 |
1993年 | 83篇 |
1992年 | 107篇 |
1991年 | 90篇 |
1990年 | 79篇 |
1989年 | 60篇 |
1988年 | 68篇 |
1987年 | 55篇 |
1986年 | 74篇 |
1985年 | 45篇 |
1984年 | 54篇 |
1983年 | 52篇 |
1982年 | 43篇 |
1981年 | 39篇 |
1980年 | 31篇 |
1979年 | 42篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1975年 | 18篇 |
1974年 | 30篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
D. A. Hartman L. A. Tomchek J. R. Lugay A. C. Lewin T. T. Chau R. P. Carlson 《Inflammation research》1991,34(1-2):84-88
Melittin (MLT) (10 g/paw) and D49 (0.4 g/paw) were injected into the hind paw of male CD-1 mice and elicited 70–80% of maximal paw edema responses at 60 and 30 min after injection, respectively. D49 paw edema was significantly inhibited by anti-histamine/serotonin agents, a PAF antagonist, a PLA2 inhibitor, and some but not all 5-LO and CO inhibitors, indicating that this edema is produced by several classes of inflammatory mediators with mast cell degranulation apparently playing a major role. In contrast, MLT paw edema was not inhibited effectively using the same pharmacological agents except theophylline, suggesting it was elicited via a different sequence of inflammatory events. In summary, D49 and MLT paw edema models were found to be ineffective models to identify experimental PLA2 compounds in our laboratory. 相似文献
82.
Shigella flexneri IpaH(7.8) facilitates escape of virulent bacteria from the endocytic vacuoles of mouse and human macrophages 下载免费PDF全文
Fernandez-Prada CM Hoover DL Tall BD Hartman AB Kopelowitz J Venkatesan MM 《Infection and immunity》2000,68(6):3608-3619
The behavior of Shigella flexneri ipaH mutants was studied in human monocyte-derived macrophages (HMDM), in 1-day-old human monocytes, and in J774 mouse macrophage cell line. In HMDM, strain pWR700, an ipaH(7.8) deletion mutant of S. flexneri 2a strain 2457T, behaved like the wild-type strain 2457T. This strain caused rapid host cell death by oncosis, and few bacterial CFU were recovered after incubation in the presence of gentamicin as previously described for 2457T-infected HMDM. However, analysis of bacterial compartmentalization within endocytic vacuoles with gentamicin and chloroquine indicated that more pWR700 than 2457T was present within the endocytic vacuoles of HMDM, suggesting that ipaH(7.8) deletion mutant transited more slowly from the vacuoles to the cytoplasm. In contrast to findings with HMDM, CFU recovered from pWR700-infected mouse J774 cells were 2 to 3 logs higher than CFU from 2457T-infected J774 cells. These values exceeded CFU recovered after infection of J774 cells with plasmid-cured avirulent strain M4243A1. Incubation with gentamicin and chloroquine clearly showed that pWR700 within J774 cells was mostly present within the endocytic vacuoles. This distribution pattern was similar to that seen with M4243A1 and contrasted with the pattern seen with 2457T. Complementation of pWR700 with a recombinant clone expressing ipaH(7. 8) restored the intracellular distribution of bacteria to that seen with the wild-type strain. Strains with deletions in ipaH(4.5) or ipaH(9.8), however, behaved like 2457T in both HMDM and J774 cells. The distribution profile of pWR700 in 1-day-old monocytes was similar to that seen in J774 cells. Like infected J774 cells, 1-day-old human monocytes demonstrated apoptosis upon infection with virulent Shigella. These results suggest that a role of the ipaH(7. 8) gene product is to facilitate the escape of the virulent bacteria from the phagocytic vacuole of monocytes and macrophages. 相似文献
83.
Kerr AR Irvine JJ Search JJ Gingles NA Kadioglu A Andrew PW McPheat WL Booth CG Mitchell TJ 《Infection and immunity》2002,70(3):1547-1557
Variations in the host response during pneumonia caused by Streptococcus pneumoniae in susceptible (CBA/Ca) and resistant (BALB/c) inbred mouse strains were investigated. Significant differences were detected in survival time, core body temperature, lung-associated and systemic bacterial loads, mast cell numbers, magnitude and location of cytokine production, lung disruption, and ability of isolated lung cells to release the cytokine tumor necrosis factor (TNF) alpha in vitro. Overall, the results indicate that the reduced capacity of CBA/Ca mice to induce rapid TNF activity within the airways following infection with S. pneumoniae may be a factor in their elevated susceptibility to pneumococcal pneumonia. 相似文献
84.
Detection of Active Infection in Nonhuman Primates with Lyme Neuroborreliosis: Comparison of PCR, Culture, and a Bioassay 下载免费PDF全文
Andrew R. Pachner Wei-Fen Zhang Henry Schaefer Susan Schaefer Tim ONeill 《Journal of clinical microbiology》1998,36(11):3243-3247
Ideally a diagnosis of infection of the central nervous system (CNS) is made by culture of the etiologic pathogen, but Borrelia burgdorferi, the causative agent of Lyme neuroborreliosis (LNB), is rarely cultured from the cerebrospinal fluid (CSF). PCR and measurement of specific antibody in the CSF also have their limitations. The role of available assays for LNB has not been studied carefully in a comparative investigation. There is a need to assess the reliability of assays and to increase the ability to document active infection in the CNS. The recent development of the nonhuman primate (NHP) model of LNB allowed us to address this need in a faithful model of human LNB. In this study we compared the abilities of PCR and culture to detect the presence of spirochetes in the CSF and brain tissue of infected NHPs and related these measures of infection to the development of anti-B. burgdorferi antibody. We also tested a bioassay, the mouse infectivity test (MIT), in this model. Fourteen of 16 CSFs from four NHPs were positive by at least one of these techniques. Detection of spirochetes in the CSF by PCR, the MIT, and culture was inversely related to the concomitant presence of anti-B. burgdorferi antibody intrathecally. The performance of any particular test was associated with the strength of the host immune response. In early CNS infection, when anti-B. burgdorferi antibody had not yet appeared, or in immunocompromised hosts, the MIT compared favorably to culture and PCR for infected NHPs; antibody in the CSF was the most useful assay for immunocompetent NHPs. 相似文献
85.
The perforant-path projection to the hippocampus forms synapses in the apical tuft of CA1 pyramidal neurons. We used computer modeling to examine the function of these distal synaptic inputs, which led to three predictions that we confirmed in experiments using rat hippocampal slices. First, activation of CA1 neurons by the perforant path is limited, a result of the long distance between these inputs and the soma. Second, activation of CA1 neurons by the perforant path depends on the generation of dendritic spikes. Third, the forward propagation of these spikes is unreliable, but can be facilitated by modest activation of Schaffer-collateral synapses in the upper apical dendrites. This 'gating' of dendritic spike propagation may be an important activation mode of CA1 pyramidal neurons, and its modulation by neurotransmitters or long-term, activity-dependent plasticity may be an important feature of dendritic integration during mnemonic processing in the hippocampus. 相似文献
86.
87.
Comparison of the smoking behaviour and attitudes of smokers who attribute respiratory symptoms to smoking with those who do not. 下载免费PDF全文
General practitioners' (GPs') advice against smoking helps smokers to stop; unfortunately, GPs cannot predict which patients will quit following advice. This postal questionnaire survey suggests that where smokers attribute their respiratory symptoms to smoking, they are eight times (95% confidence interval [CI] = 3.0-23.3) more likely to believe that their health will improve if they stop smoking and six times (95% CI = 1.4-23.3) more likely to intend to stop smoking. 相似文献
88.
Lorne M. Hartman Dr. 《Clinical psychology review》1983,3(4):435-456
This article represents an attempt to clarify questions posed by evidence of varying pathways to change in social anxiety. A new perspective is developed which addresses these questions and, importantly, lays the foundation for an innovative treatment approach. Essentially, social anxiety is construed here as the product of a disorganization in which feelings and cognitions (both conscious and preconscious) about the self, about other people, and about the relations between self and others are organized. Specifically, the socially anxious client experiences others autocentrically: that is, in terms of how the other person perceives, evaluates and affects one's own self. The result is a narrowed capacity for experiencing others. The goal of treatment in the new approach advocated here is to allow the individual to understand, appreciate and share the feelings, thoughts and experience of other people. Therapy is directed toward getting clients out of themselves and into other people. 相似文献
89.
Edward D. Levin Todd C. Brady Elizabeth Crapo Hochrein Tim D. Oury Lena M. Jonsson Stefan L. Marklund James D. Crapo 《Behavior genetics》1998,28(5):381-390
Extracellular superoxide dismutase (EC-SOD) controls the availability of extracellular superoxide (O
2
-
), which is important for a variety of physiological pathways, including the primary means of inactivating nitric oxide (NO). The role of EC-SOD in neurobehavioral function has been until now unexplored. In the current studies, the phenotypic expression of genotypic alterations of EC-SOD production in mice were characterized for spatial learning and memory. Dramatic impairments in spatial learning in the win-shift 8-arm radial maze were seen in both EC-SOD knockout mice and EC-SOD overexpressing mice. The EC-SOD overexpressing mice were further characterized as having significant deficits in a repeated acquisition task in the radial-arm maze, which permitted the dissociation of long and short-term learning. Long-term learning was significantly impaired by EC-SOD overexpression, whereas short-term learning was not significantly affected by EC-SOD overexpression. NO systems have been shown to be importantly involved in learning and memory. This may be important in the current studies because EC-SOD has primary control over the inactivation of NO. We found that EC-SOD overexpressing mice were resistant to the cognitive effects of L-NAME (NG-nitro-L-arginine methyl ester hydrochloride), an NO synthase inhibitor. Decreased NO catabolism in these mice may have served to counter the effects of NOS inhibition by L-NAME. The current finding that EC-SOD levels that were either higher or lower than controls impaired learning demonstrates that the proper control of brain extracellular (O
2
-
) may be more vital than merely reduction of brain extracelluar (O
2
-
) in maintaining adequate learning function. 相似文献
90.
A mutation in the gene TNFRSF11B encoding osteoprotegerin causes an idiopathic hyperphosphatasia phenotype 总被引:5,自引:0,他引:5