全文获取类型
收费全文 | 20437篇 |
免费 | 1391篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 125篇 |
儿科学 | 432篇 |
妇产科学 | 268篇 |
基础医学 | 2718篇 |
口腔科学 | 330篇 |
临床医学 | 2558篇 |
内科学 | 3575篇 |
皮肤病学 | 200篇 |
神经病学 | 1820篇 |
特种医学 | 708篇 |
外科学 | 2832篇 |
综合类 | 231篇 |
一般理论 | 28篇 |
预防医学 | 2664篇 |
眼科学 | 430篇 |
药学 | 1595篇 |
中国医学 | 35篇 |
肿瘤学 | 1335篇 |
出版年
2024年 | 20篇 |
2023年 | 136篇 |
2022年 | 239篇 |
2021年 | 486篇 |
2020年 | 308篇 |
2019年 | 436篇 |
2018年 | 511篇 |
2017年 | 390篇 |
2016年 | 430篇 |
2015年 | 580篇 |
2014年 | 744篇 |
2013年 | 968篇 |
2012年 | 1639篇 |
2011年 | 1666篇 |
2010年 | 950篇 |
2009年 | 887篇 |
2008年 | 1456篇 |
2007年 | 1598篇 |
2006年 | 1448篇 |
2005年 | 1445篇 |
2004年 | 1411篇 |
2003年 | 1331篇 |
2002年 | 1150篇 |
2001年 | 142篇 |
2000年 | 105篇 |
1999年 | 160篇 |
1998年 | 219篇 |
1997年 | 150篇 |
1996年 | 132篇 |
1995年 | 101篇 |
1994年 | 111篇 |
1993年 | 87篇 |
1992年 | 49篇 |
1991年 | 43篇 |
1990年 | 29篇 |
1989年 | 33篇 |
1988年 | 23篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 26篇 |
1984年 | 24篇 |
1983年 | 28篇 |
1982年 | 23篇 |
1981年 | 25篇 |
1980年 | 20篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 14篇 |
1975年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Shigemitsu Iwai MD Kei Torikai MD Chris M. Coppin MD Yoshiki Sawa MD 《Journal of artificial organs》2007,10(1):29-35
Currently used bioprosthetic valves have several limitations such as calcification and functional deterioration, and revitalization
through cellular ingrowth is impossible. To overcome these obstacles, we have developed a minimally immunogenic tissue-engineered
valve that consists of an unfixed, decellularized porcine valve scaffold capable of being spontaneously revitalized in vivo
after implantation. Porcine aortic root tissue was decellularized using detergents such as sodium lauryl sulfate and Triton
X-100. The porcine valve was treated very gently and plenty of time was allowed for constituents to diffuse in and out of
the matrix. In a preliminary study, a piece of decellularized porcine valve tissue was implanted into the rat subdermal space
for 14 and 60 days and the structural integrity and calcification were evaluated. As an in vivo valve replacement model, the
decellularized porcine valve was implanted in the pulmonary valve position in dogs and functional and histological evaluation
was performed after 1, 2, and 6 months. Histological examination showed that the newly developed detergent treatment effectively
removed cellular debris from the porcine aortic tissue. Decellularized porcine valve tissue implanted subdermally in rats
showed minimal inflammatory cell infiltration and calcification. In the valve replacement model, spontaneous reendothelialization
and repopulation of the medial cells were observed within 2 months, and good valve function without regurgitation was observed
by echocardiography up to 6 months. The minimally immunogenic decellularized porcine valve proved effective in mitigating
postimplant calcification and provided a suitable matrix for revitalizing prostheses through in situ recellularization, cellular
ingrowth, and tissue remodeling. 相似文献
102.
103.
Rapid detection and identification of human adenovirus species by adenoplex, a multiplex PCR-enzyme hybridization assay
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pehler-Harrington K Khanna M Waters CR Henrickson KJ 《Journal of clinical microbiology》2004,42(9):4072-4076
Human adenoviruses (AdV) have been implicated in a wide variety of diseases and are ubiquitous in populations worldwide. These agents are of concern particularly in immunocompromised patients, children, and military recruits, resulting in severe disease or death. Clinical diagnosis of AdV is usually achieved through routine viral cell culture, which can take weeks for results. Immunofluorescence and enzyme-linked immunosorbent assay-based techniques are more timely but lack sensitivity. The ability to distinguish between the six different AdV species (A to F) is diagnostically relevant, as infections with specific AdV species are often associated with unique clinical outcomes and epidemiological features. Therefore, we developed a multiplex PCR-enzyme hybridization assay, the Adenoplex, using primers to the fiber gene that can simultaneously detect all six AdV species A through F in a single test. The limit of detection (LOD) based on the viral 50% tissue culture infective dose/ml for AdV A, B, C, D, E, and F was 10(-2), 10(-1), 10(-1), 10(-2), 10(-1), and 10(-2), respectively. Similarly, the LOD for the six DNA controls ranged from 10(2) to 10(3) copies/ml. Twelve common respiratory pathogens were tested with the Adenoplex, and no cross-reactivity was observed. We also validated our assay using clinical specimens spiked with different concentrations of AdV strains of each species type and tested by multiplex PCR and culture. The results demonstrated an overall sensitivity and specificity of Adenoplex of 100%. This assay can be completed in as few as 5 h and provides a rapid, specific, and sensitive method to detect and subtype AdV species A through F. 相似文献
104.
Max J. Kurz Konstantinos Pothakos Sakeena Jamaluddin Melissa Scott-Pandorf Chris Arellano Yuen-Sum Lau 《Neuroscience letters》2007
The purpose of this investigation was to determine if a chronic Parkinson's disease mouse model will display less certainty in its gait pattern due to basal ganglia dysfunction. A chronic Parkinson's disease mouse model was induced by injecting male C57/BL mice with 10 doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (25 mg/kg) (MPTP) and probenecid (250 mg/kg) (P) over 5 weeks. This chronic model produces a severe and persistent loss of nigrostriatal neurons resulting in dopamine depletion and locomotor impairment. The control mice were treated with probenecid alone. Fifteen weeks after the last MPTP/P treatment, the mice were videotaped in the sagittal plane with a digital camera (60 Hz) as they ran on a motorized treadmill at a speed of 10 m/min. The indices of gait and gait variability were calculated. Stride length was significantly (p = 0.016) more variable in the chronic MPTP/P mice. Additionally, the chronic MPTP/P mice had a statistically less certain gait pattern when compared to the control mice (p = 0.02). These results suggest that variability in the gait pattern can be used to evaluate changes in neural function. Additionally, our results imply that disorder of the basal ganglia results in less certainty in modulating the descending motor command that controls the gait pattern. 相似文献
105.
Field evaluation of the efficacy and immunogenicity of recombinant hepatitis B vaccine without HBIG in newborn Vietnamese infants 总被引:4,自引:0,他引:4
A study involving more than 2,000 infants was conducted in Vietnam to assess the field effectiveness and immunogenicity of recombinant hepatitis B vaccine given at birth, 1 month, 2 months, without concomitant hepatitis B immune globulin (HBIG). All received a 5 microg dose of H-B-VAX II at birth. Infants born to non-carrier mothers (Group 1; N = 1798) then received 2.5 microg doses at 1 and 2 months of age, while infants of HBeAg-negative (Group 2; N = 125) or HBeAg-positive (Group 3; N = 88) carrier mothers received 5 microg doses. No Group 1 or 2 vaccinees were infected. In Group 3, 12 (14.6%) of 82 infants did become infected (estimated efficacy 84%). 98.0-98.6% of uninfected infants who were tested for anti-HBs developed a seroprotective concentration > or = 10 IU/L. In hyperendemic Vietnam, where routine maternal screening and passive-active prophylaxis of high-risk infants with vaccine plus HBIG is not feasible, administration of vaccine alone to all newborns may control effectively HBV infection. 相似文献
106.
Absence of proteinase-activated receptor-1 signaling affords protection from bleomycin-induced lung inflammation and fibrosis
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Howell DC Johns RH Lasky JA Shan B Scotton CJ Laurent GJ Chambers RC 《The American journal of pathology》2005,166(5):1353-1365
Activation of the coagulation cascade is commonly observed in the lungs of patients with both acute and chronic inflammatory and fibrotic lung disorders, as well as in animal models of these disorders. The aim of this study was to examine the contribution of the major thrombin receptor, proteinase-activated receptor-1 (PAR-1), during the acute inflammatory and chronic fibrotic phases of lung injury induced by intratracheal instillation of bleomycin in mice. Inflammatory cell recruitment and increases in bronchoalveolar lavage fluid (BALF) protein were attenuated by 56 +/- 10% (P < 0.05) and 53 +/- 12% (P < 0.05), respectively, in PAR-1-deficient (PAR-1-/-) mice compared with wild-type (WT) mice. PAR-1-/- mice were also protected from bleomycin-induced pulmonary fibrosis with total lung collagen accumulation reduced by 59 +/- 5% (P < 0.05). The protection afforded by PAR-1 deficiency was accompanied by significant reductions in pulmonary levels of the potent PAR-1-inducible proinflammatory and profibrotic mediators, monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-beta-1 (TGF-beta1), and connective tissue growth factor/fibroblast-inducible secreted protein-12 (CTGF/FISP12). In addition, PAR-1 was highly expressed in inflammatory and fibroproliferative lesions in lung sections obtained from patients with fibrotic lung disease. These data show for the first time that PAR-1 signaling plays a key role in experimentally induced lung injury, and they further identify PAR-1 as one of the critical receptors involved in orchestrating the interplay between coagulation, inflammation, and remodeling in response to tissue injury. 相似文献
107.
Comparative genomic hybridization pattern distinguishes T-cell/histiocyte-rich B-cell lymphoma from nodular lymphocyte predominance Hodgkin's lymphoma 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Franke S Wlodarska I Maes B Vandenberghe P Achten R Hagemeijer A De Wolf-Peeters C 《The American journal of pathology》2002,161(5):1861-1867
Several lines of evidences suggest that T cell/histiocyte-rich B-cell lymphoma (T/HRBCL) represents an aggressive variant of the clinically indolent entity nodular lymphocyte predominance Hodgkin's lymphoma (LPHL). Still, this view has not yet been supported by firm genetic evidence. In this study, we analyzed 17 T/HRBCL cases using comparative genomic hybridization (CGH) combined with microdissection of single CD20+ neoplastic cells and DNA amplification by degenerate oligonucleotide primed-polymerase chain reaction, an approach we previously used in LPHL. Genomic imbalances were detected in all cases (in total, 80 changes). The most common imbalances included gain of Xq, 4q13q28, Xp21p11, and 18q21, and loss of 17p. Of note, a partial gain of 4q, a rare change in lymphoma, is also among the genomic imbalances most frequently encountered in LPHL. On the other hand, the CGH profiles of T/HRBCL and LPHL showed several distinct features, in particular with respect to the number of genomic imbalances (average of 4.7 in T/HRBCL versus 10.8 in LPHL) and their distribution (usually 1 to 5 in T/HRBCL versus 6 to 22 in LPHL). Altogether, our CGH findings of shared as well as distinctive cytogenetic features in both diseases suggest that T/HRBCL constitutes a separate lymphoma entity, possibly originating from the same precursor cell as LPHL. 相似文献
108.
Rorden C Driver J 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2001,137(3-4):487-496
Research on visual attention has demonstrated that covert attention can be focused on particular locations within one hemifield,
but that a specific "meridian" cost may also be found for shifting attention between hemifields. These issues have received
less consideration for audition, even though reliable behavioral measures for the effects of spatial attention on hearing
are now available. We examined the spatial distribution of covert attention in an auditory task following spatially non-predictive
peripheral auditory cues (which should induce exogenous attention shifts), or following symbolic central cues that predicted
the likely location for the auditory target (to induce endogenous attention shifts). In both cases, we found that attention
can be focused not only on one hemifield versus another, but also within one hemifield in an auditory task. However, there
was no unequivocal evidence for a meridian effect in audition.
Electronic Publication 相似文献
109.
110.
Type 1 immunity provides both optimal mucosal and systemic protection against a mucosally invasive, intracellular pathogen 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
It has been hypothesized that optimal vaccine immunity against mucosally invasive, intracellular pathogens may require the induction of different types of immune responses in mucosal and systemic lymphoid tissues. Mucosal type 2/3 responses (producing interleukin-4 [IL-4], IL-6 and/or transforming growth factor beta) could be necessary for optimal induction of protective secretory immunoglobulin A responses. On the other hand, systemic type 1 responses (including gamma interferon [IFN-gamma], tumor necrosis factor alpha, and optimal cytotoxic T-cell responses) are likely to be critical for protection against the disseminated intracellular replication that occurs after mucosal invasion. Despite these predictions, we recently found that vaccines inducing highly polarized type 1 immunity in both mucosal and systemic tissues provided optimal mucosal and systemic protection against the protozoan pathogen Trypanosoma cruzi. To further address this important question in a second model system, we now have studied the capacity of knockout mice to develop protective immune memory. T. cruzi infection followed by nifurtimox treatment rescue was used to immunize CD4, CD8, beta2-microglobulin, inducible nitric oxide synthase (iNOS), IL-12, IFN-gamma, and IL-4 knockout mice. Despite the previously demonstrated importance of CD4(+) T cells, CD8(+) T cells, and nitric oxide for T. cruzi immunity, CD4, CD8, and iNOS knockout mice developed mucosal and systemic protective immunity. However, IL-12, IFN-gamma, and beta2-microglobulin-deficient mice failed to develop mucosal or systemic protection. In contrast, IL-4 knockout mice developed maximal levels of both mucosal and systemic immune protection. These results strongly confirm our earlier conclusion from studies with polarizing vaccination protocols that type 1 immunity provides optimal mucosal and systemic protection against a mucosally invasive, intracellular pathogen. 相似文献