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31.
32.
The locus of enterocyte effacement (LEE)-encoded regulator controls expression of both LEE- and non-LEE-encoded virulence factors in enteropathogenic and enterohemorrhagic Escherichia coli 总被引:7,自引:0,他引:7
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Elliott SJ Sperandio V Girón JA Shin S Mellies JL Wainwright L Hutcheson SW McDaniel TK Kaper JB 《Infection and immunity》2000,68(11):6115-6126
Regulation of virulence gene expression in enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) is incompletely understood. In EPEC, the plasmid-encoded regulator Per is required for maximal expression of proteins encoded on the locus of enterocyte effacement (LEE), and a LEE-encoded regulator (Ler) is part of the Per-mediated regulatory cascade upregulating the LEE2, LEE3, and LEE4 promoters. We now report that Ler is essential for the expression of multiple LEE-located genes in both EPEC and EHEC, including those encoding the type III secretion pathway, the secreted Esp proteins, Tir, and intimin. Ler is therefore central to the process of attaching and effacing (AE) lesion formation. Ler also regulates the expression of LEE-located genes not required for AE-lesion formation, including rorf2, orf10, rorf10, orf19, and espF, indicating that Ler regulates additional virulence properties. In addition, Ler regulates the expression of proteins encoded outside the LEE that are not essential for AE lesion formation, including TagA in EHEC and EspC in EPEC. delta ler mutants of both EPEC and EHEC show altered adherence to epithelial cells and express novel fimbriae. Ler is therefore a global regulator of virulence gene expression in EPEC and EHEC. 相似文献
33.
Pneumococcal surface protein A (PspA) is serologically highly variable and is expressed by all clinically important capsular serotypes of Streptococcus pneumoniae. 总被引:3,自引:9,他引:3
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M J Crain W D Waltman nd J S Turner J Yother D F Talkington L S McDaniel B M Gray D E Briles 《Infection and immunity》1990,58(10):3293-3299
Pneumococcal surface protein A (PspA) has been shown previously to elicit antibodies protective against pneumococcal infection and to be necessary for full pneumococcal virulence in mice. The protein was originally defined by the two mouse monoclonal antibodies Xi64 and Xi126, which together recognized PspA on 14% of pneumococcal isolates. Some PspA molecules reacted with both antibodies, but most reacted with only one or the other. In the present study we demonstrated that PspA is produced by all pneumococci, confirming our hypothesis that there are variants of PspA which are not detected by Xi64 and Xi126. We produced a rabbit antiserum and five additional monoclonal antibodies specific for PspA for these studies. The rabbit antiserum reacted with each of 95 pneumococcal isolated tested, comprising 16 capsular serotypes. One or more of the seven monoclonal anti-PspA antibodies reacted with 95% (53 of 57) of pneumococcal isolates tested. The specificity of the monoclonal and polyclonal antibodies to PspA was confirmed in two ways: (i) by detection of molecules on wild-type pneumococci that are identical in molecular weight to those detected in Western blots (immunoblots) with Xi64 and Xi126 and (ii) by the use of mutants of Streptococcus pneumoniae that fail to produce PspA or that produce a truncated form of PspA. By using the seven monoclonal antibodies, we observed 31 PspA types among the 57 isolates. When the 53 strains reactive with the monoclonal antibodies were analyzed by capsular type as well as by serologic type and molecular weight of PspA, we observed 50 different clonotypes of pneumococci. 相似文献
34.
Diffusion in gel-enzyme-linked immunosorbent assay—a new serological test for leptospirosis
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A new serological test, diffusion in gel-enzyme-linked immunosorbent assay (DIG-ELISA) was developed and compared with the microscopic agglutination test (MAT) for the serological diagnosis of leptospirosis. The results suggest that DIG-ELISA is a viable alternative to the MAT because of its simplicity, sensitivity, versatility and potential for standardisation. 相似文献
35.
Marjolein P de Vries Lisette van den Bemt Karen Aretz Bart PA Thoonen Jean WM Muris Arnold DM Kester Sonja Cloosterman CP Onno van Schayck 《The British journal of general practice》2007,57(536):184-190
BACKGROUND: The efficacy of bed covers that are impermeable to house dust mites has been disputed. AIM: The aim of the present study was to investigate whether the combination of 'house dust mite impermeable' covers and a self-management plan, based on peak flow values and symptoms, leads to reduced use of inhaled corticosteroids (ICS) than self-management alone. DESIGN OF STUDY: Prospective, randomised, double blind, placebo-controlled trial. SETTING: Primary care in a south-eastern region of the Netherlands. METHOD: Asthma patients aged between 16 and 60 years with a house dust mite allergy requiring ICS were randomised to intervention and placebo groups. They were trained to use a self-management plan based on peak flow and symptoms. After a 3-month training period, the intervention commenced using house dust mite impermeable and placebo bed covers. The follow-up period was 2 years. Primary outcome was the use of ICS; secondary outcomes were peak expiratory flow parameters, asthma control, and symptoms. RESULTS: One hundred and twenty-six patients started the intervention with house dust mite impermeable or placebo bed covers. After 1 and 2 years, significant differences in allergen exposure were found between the intervention and control groups (P<0.001). No significant difference between the intervention and control groups was found in the dose of ICS (P = 0.08), morning peak flow (P = 0.52), peak flow variability (P = 0.36), dyspnoea (P = 0.46), wheezing (P = 0.77), or coughing (P = 0.41). There was no difference in asthma control between the intervention and control groups. CONCLUSION: House dust mite impermeable bed covers combined with self-management do not lead to reduced use of ICS compared with self-management alone. 相似文献
36.
Tissue and lineage-specific variation in inactive X chromosome expression of the murine Smcx gene 总被引:2,自引:0,他引:2
To understand how gene expression patterns are established on the inactive
X chromosome during development, we have studied the murine gene Smcx,
which is expressed from both the active and inactive mouse X chromosomes.
In all tissues assayed, Smcx only partially escapes X inactivation, with
expression levels from the inactive X allele approximately 30-65% that of
the active X allele. Additionally, inactive X expression levels differed
between extraembryonic and embryonic tissues and among different tissues
from newborn and adult mice. Imprinted extraembryonic tissue had the lowest
levels of inactive X Smcx expression, whereas the highest levels were in
heart. These data suggest that the chromosomal basis of X inactivation
differs among tissues, perhaps reflecting differences in the timing or
regulation of inactivation in these cell lineages.
相似文献
37.
Curtas AR Wood HG Allaire PE McDaniel JC Day SW Olsen DB 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2002,48(5):552-561
To finalize the design of the next generation of the HeartQuest left ventricular assist device, a suitable impeller had to be designed and tested. The new prototype was based on calculations and test results of previous designs, but required several changes to decrease the size. For most pump designs, this is a simple matter of altering impeller geometry and rotational speed to achieve the desired pressure rise and flow rate. However, this particular pump was limited by housing geometry and the magnetic bearings that support the impeller. Without much freedom in the overall impeller size, the only parameters open to the designers were the blade profiles and the rotating speed. Rather than build several candidates and test them in a rig at enormous cost, computational models of several designs were tested and analyzed. This not only saved money, but also sped up the development time for the project. The computer models were developed in TASCflow, a computational fluid dynamics software package from AEA Technologies. This paper analyzes the data from several of the selected models, paying close attention to pumping performance and general trends from specific design changes. 相似文献
38.
George N Papanikolaou Maria S Baltogianni Despina G Contopoulos-Ioannidis Anna-Bettina Haidich Ioannis A Giannakakis John PA Ioannidis 《BMC medical research methodology》2001,1(1):3
Background
Guidelines published in major medical journals are very influential in determining clinical practice. It would be essential to evaluate whether conflicts of interests are disclosed in these publications. We evaluated the reporting of conflicts of interest and the factors that may affect such disclosure in a sample of 191 guidelines on therapeutic and/or preventive measures published in 6 major clinical journals (Annals of Internal Medicine, BMJ, JAMA, Lancet, New England Journal of Medicine, Pediatrics) in 1979, 1984, 1989, 1994 and 1999.Results
Only 7 guidelines (3.7%) mentioned conflicts of interest and all were published in 1999 (17.5% (7/40) of guidelines published in 1999 alone). Reporting of conflicts of interest differed significantly by journal (p=0.026), availability of disclosure policy by the journal (p=0.043), source of funding (p < 0.001) and number of authors (p=0.004). In the entire database of 191 guidelines, a mere 18 authors disclosed a total of 24 potential conflicts of interest and most pertained to minor issues.Conclusions
Despite some recent improvement, reporting of conflicts of interest in clinical guidelines published in influential journals is largely neglected.39.
Dal Zotto L; Quaderi NA; Elliott R; Lingerfelter PA; Carrel L; Valsecchi V; Montini E; Yen CH; Chapman V; Kalcheva I; Arrigo G; Zuffardi O; Thomas S; Willard HF; Ballabio A; Disteche CM; Rugarli EI 《Human molecular genetics》1998,7(3):489-499
We have recently reported isolation of the gene responsible for X- linked
Opitz G/BBB syndrome, a defect of midline development. MID1 is located on
the distal short arm of the human X chromosome (Xp22. 3) and encodes a
novel member of the B box family of zinc finger proteins. We have now
cloned the murine homolog of MID1 and performed preliminary expression
studies during development. Mid1 expression in undifferentiated cells in
the central nervous, gastrointestinal and urogenital systems suggests that
abnormal cell proliferation may underlie the defect in midline development
characteristic of Opitz syndrome. We have also found that Mid1 is located
within the mouse pseudoautosomal region (PAR) in Mus musculus , while it
seems to be X- specific in Mus spretus. Therefore, Mid1 is likely to be a
recent acquisition of the M. musculus PAR. Genetic and FISH analyses also
demonstrated a high frequency of unequal crossovers in the murine PAR,
creating spontaneous deletion/duplication events involving Mid1. These data
provide evidence for the first time that genetic instability of the PAR may
affect functionally important genes. In addition, we show that MID1 is the
first example of a gene subject to X-inactivation in man while escaping it
in mouse. These data contribute to a better understanding of the molecular
content and evolution of the rodent PAR.
相似文献
40.
A model of corrective gene transfer in X-linked ichthyosis 总被引:5,自引:0,他引:5
Freiberg RA; Choate KA; Deng H; Alperin ES; Shapiro LJ; Khavari PA 《Human molecular genetics》1997,6(6):927-933
Single gene recessive genetic skin disorders offer attractive prototypes
for the development of therapeutic cutaneous gene delivery. We have
utilized X-linked ichthyosis (XLI), characterized by loss of function of
the steroid sulfatase arylsulfatase C (STS), to develop a model of
corrective gene delivery to human skin in vivo. A new retroviral expression
vector was produced and utilized to effect STS gene transfer to primary
keratinocytes from XLI patients. Transduction was associated with
restoration of full-length STS protein expression as well as steroid
sulfatase enzymatic activity in proportion to the number of proviral
integrations in XLI cells. Transduced and uncorrected XLI keratinocytes,
along with normal controls, were then grafted onto immunodeficient mice to
regenerate full thickness human epidermis. Unmodified XLI keratinocytes
regenerated a hyperkeratotic epidermis lacking STS expression with
defective skin barrier function, effectively recapitulating the human
disease in vivo. Transduced XLI keratinocytes from the same patients,
however, regenerated epidermis histologically indistinguishable from that
formed by keratinocytes from patients with normal skin. Transduced XLI
epidermis demonstrated STS expression in vivo by immunostaining as well as
a normalization of histologic appearance at 5 weeks post-grafting. In
addition, transduced XLI epidermis demonstrated a return of barrier
function parameters to normal. These findings demonstrate corrective gene
delivery in human XLI patient skin tissue at both molecular and functional
levels and provide a model of human cutaneous gene therapy.
相似文献