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Relative carriage rates of nuclear dehydrogenating clostridia in two populations of different colorectal cancer risk
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Carriage of nuclear dehydrogenating clostridia has been associated with colon cancer and implicated in its aetiology. This study has compared the carriage of these organisms in a British population at high risk for the development of colon cancer with a low risk Nigerian population. Clostridia were found in all of the stools from both populations. Nuclear dehydrogenating clostridia were only found in the stools of the British subjects (32%). These results support the suggestion that the carriage rate of nuclear dehydrogenating clostridia in a population is related to the risk of colon cancer. 相似文献
6.
Simplified sample processing combined with a sensitive one-tube nested PCR assay for detection of Pneumocystis carinii in respiratory specimens.
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Early diagnosis of Pneumocystis carinii pneumonia, a life-threatening complication in immunosuppressed patients, may lower morbidity and mortality. We have developed a one-tube nested PCR assay for the detection of P. carinii in respiratory specimens. Four primers were selected from the sequence of the small-subunit rRNA gene of P. carinii to amplify a 265-bp fragment, and their specificities for P. carinii were confirmed by both theoretical evaluations (by computer-assisted comparison with the sequences in GenBank) and empirical evaluations (with DNA from medically important fungi and diagnostic samples). The assay was optimized for routine diagnostic use. Processing of the clinical samples is rapid and simple (digestion with proteinase K directly in PCR buffer at room temperature in the presence of 10% Chelex 100 and no further purification steps). Bovine serum albumin (1 mg/ml) and glycerol (10%) in the amplification buffer reduced the number of samples inhibitory to the PCR, as assessed by control reactions containing a size-modified target. A total of 749 clinical specimens (312 bronchoalveolar lavage, 403 sputum or induced sputum, and 34 other specimens) from 507 patients (295 human immunodeficiency virus [HIV]-infected and 164 non-HIV-infected patients and 48 patients whose HIV status was unknown) were tested by PCR, and the results were compared with those of an indirect immunofluorescence assay (IFA). Concordant results were obtained for 732 samples (646 negative and 86 positive). There were 17 discrepant results: 12 were PCR positive and IFA negative, and 5 were PCR negative and IFA positive. After resolution of the discrepant results by review of the patients' clinical data, the sensitivity and specificity were 94.8 and 99.1%, respectively, for PCR and 93.8 and 100%, respectively, for IFA. In conclusion, the short procedure time and the technical ease of this PCR assay render it suitable for implementation in routine diagnostic laboratories. 相似文献
7.
Triple combination antiretroviral therapy can reduce HIV-1 infection to a relatively small pool of latently infected cells. To eliminate this residual source of virus, new therapies designed to activate latently infected cells are currently being tested. We therefore investigated the kinetics of in vitro HIV-1 RNA induction using chronically infected U1 cells. A new two-probe fluorescence in situ hybridization (double ISH) method was devised to simultaneously assess total HIV-1 RNA (T-RNA) and unspliced HIV-1 RNA (U-RNA) expression in individual cells. Activation of the U1 cells resulted in increasing expression of T-RNA between 0 and 24 h with lagging expression of U-RNA between 6 and 30 h. Both the positive area per cell and the number of positive cells increased with time. Although activation induced 98.5% of the cells to express HIV-1 T-RNA by 24 h, 52% remained negative for U-RNA. In contrast, 100% of 8E5 cells, which constitutively express HIV-1, scored positive for U-RNA as well as T-RNA with the double ISH. This study provides, for the first time, a semiquantitative cell-by-cell analysis of HIV-1 mRNA subsets in latently infected cells. Our results establish the advantages of using double fluorescence ISH to study gene expression and demonstrate that chronically infected U1 cells remain in a partially induced state despite potent activation. 相似文献
8.
Development of hatching blastocysts from immature human oocytes following in-vitro maturation and fertilization using a co-culture system 总被引:8,自引:0,他引:8
Hwu YM; Lee RK; Chen CP; Su JT; Chen YW; Lin SP 《Human reproduction (Oxford, England)》1998,13(7):1916-1921
Recently, in-vitro maturation (IVM) of immature human oocytes recovered
from non-stimulated follicles has been applied in the treatment of
infertility. However, in previous reports, very few embryos cultured in
conventional medium have reached the expanded blastocyst stage following
in-vitro maturation and fertilization (IVM/IVF). The objective of this
study was to investigate whether the developmental competence of human
embryos following IVM/IVF could be enhanced by the use of a human ampullary
cell co-culture system. Immature human oocytes were aspirated from small
follicles at Caesarean section and then cultured in medium containing human
menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes
were randomly cultured either in conventional culture medium alone or in
the co-culture system. Of 48 embryos cultured in conventional medium alone,
all arrested at the 2-16- cell stage on day 3 after insemination. Of 46
embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at
the 2-16-cell stage. Six embryos (13%) developed to the morula stage.
Fourteen embryos (30.4%) developed to expanded blastocysts and two
blastocysts were hatching on day 7 after insemination. We conclude that
co-culture significantly enhances the development of blastocysts in embryos
resulting from IVM/IVF.
相似文献
9.
Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization 总被引:11,自引:0,他引:11
The development and application of fluorescence in-situ hybridization
(FISH) has opened the way for comprehensive studies on numerical chromosome
abnormalities in human spermatozoa. FISH can be rapidly applied to large
numbers of spermatozoa and thus overcomes the major limitation of
karyotyping spermatozoa after penetration of zona-free hamster oocytes. The
simultaneous hybridization of two or more chromosome-specific probes to
spermatozoa and subsequent detection of the bound probes using different
fluorescent detection systems enables two or more chromosomes to be
localized simultaneously in the same spermatozoon and provides a technique
for undertaking reasonable estimates of aneuploidy. The most commonly used
probes are those which bind to the centromeric region of specific
chromosomes. Most studies to date have concentrated on estimating
aneuploidy in spermatozoa from normospermic men, although reports are
beginning to appear on aneuploidy in spermatozoa from subfertile and
infertile men. Multi- probe FISH studies have generally reported disomy
(hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary
evidence that some chromosomes such as X, Y and 21 are predisposed towards
higher rates of non-disjunction during spermatogenesis. There are also
suggestions of inter-donor variability in aneuploidy frequencies for
specific chromosomes, although this requires confirmation in larger
studies. While FISH is clearly a powerful technique that has many
applications in reproductive medicine, it must also be realized that it
does have limitations and the technology itself is still evolving and has
yet to be fully validated on spermatozoa.
相似文献
10.
Preliminary observations on polar body extrusion and pronuclear formation in human oocytes using time-lapse video cinematography 总被引:10,自引:17,他引:10
Payne D; Flaherty SP; Barry MF; Matthews CD 《Human reproduction (Oxford, England)》1997,12(3):532-541
In this study, we have used time-lapse video cinematography to study
fertilization in 50 human oocytes that had undergone intracytoplasmic sperm
injection (ICSI). Time-lapse recording commenced shortly after ICSI and
proceeded for 17-20 h. Oocytes were cultured in an environmental chamber
which was maintained under standard culture conditions. Overall, 38 oocytes
(76%) were fertilized normally, and the fertilization rate and embryo
quality were not significantly different from 487 sibling oocytes cultured
in a conventional incubator. Normal fertilization followed a defined course
of events, although the timing of these events varied markedly between
oocytes. In 35 of the 38 fertilized oocytes (92%), there were circular
waves of granulation within the ooplasm which had a periodicity of 20-53
min. The sperm head decondensed during this granulation phase. The second
polar body was then extruded, and this was followed by the central
formation of the male pronucleus. The female pronucleus formed in the
cytoplasm adjacent to the second polar body at the same time as, or
slightly after, the male pronucleus, and was subsequently drawn towards the
male pronucleus until the two abutted. Both pronuclei then increased in
size, the nucleoli moved around within the pronuclei and some nucleoli
coalesced. During pronuclear growth, the organelles contracted from the
cortex towards the centre of the oocyte, leaving a clear cortical zone. The
oocyte decreased in diameter from 112 to 106 microm (P < 0.0001) during
the course of the observation period. The female pronucleus was
significantly smaller in diameter than the male pronucleus (24.1 and 22.4
microm respectively, P = 0.008) and contained fewer nucleoli (4.2 and 7.0
respectively, P < 0.0001). After time-lapse recording, oocytes were
cultured for 48 h prior to embryo transfer or cryopreservation. Embryo
quality was related to fertilization events and periodicity of the
cytoplasmic wave, and it was found that good quality embryos arose from
oocytes that had more uniform timing from injection to pronuclear abuttal
and tended to have a longer cytoplasmic wave. In conclusion, we have shown
that time-lapse video cinematography is an excellent tool for studying
fertilization and early embryo development, and have demonstrated that
human fertilization comprises numerous complex dynamic events.
相似文献