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971.
Previous research has shown that rats develop a conditioned taste aversion after a single pairing of a distinct taste and subsequent toxicosis. The experiments reported here test the hypothesis that the expression of a taste aversion may reflect classically conditioned nausea mediated by activation of brainstem emetic centers by taste stimuli. Rats were allowed to drink a saccharin solution (1 g/l) and 10 min later were intubated with LiCl (180 mg/kg) to produce nausea. When control rats were posttested for saccharin preference they consumed less than 50% of their pretest intake. Experimental rats were injected with one of four pharmacologically distinct antiemetic drugs 30 min prior to their posttest with saccharin. Each drug significantly attenuated the aversion to saccharin at one dose level. The antiemetic drugs we used were scopolamine HBr, cyclizine, prochlorperazine dimaleate, and trimethobenzamide. These drugs had no effect on the conditioned fear of a noise that signaled foot shock or on a natural aversion to a bitter fluid (quinine monohydrochloride, 100 mg/l). Our data suggest that pharmacological suppression of the neural mechanisms of emesis selectively disrupts conditioned taste aversions, and that moderate dose levels are critical for obtaining this effect. 相似文献
972.
Chronic transfusion therapy for children with sickle cell disease and recurrent acute chest syndrome
Hankins J Jeng M Harris S Li CS Liu T Wang W 《Journal of pediatric hematology/oncology》2005,27(3):158-161
The objective was to study the effects of chronic transfusion therapy (CTX) on the prevention of new episodes of acute chest syndrome (ACS) in children with sickle cell disease (SCD) and recurrent or unusually severe ACS. A retrospective chart review was performed of patients given CTX for recurrent or severe ACS. Frequency, median severity score, and median hospital stay for ACS episodes were determined. Differences in these values before and during CTX were analyzed. Twenty-seven patients were identified. Before treatment, the ACS incidence was 1.3 episodes per patient-year; during treatment, it decreased to 0.1 episodes per patient-year (P < 0.0001). The median severity score for ACS episodes was 0.8 (range 0-5) before CTX and 0.5 (0-3) during CTX (P = 0.84). The median hospital stay was 5 days (range 3-15 days) before CTX and 3 days (2-7 days) during CTX (P = 0.38). CTX significantly reduces the incidence of ACS events among patients with a history of recurrent or severe episodes but does not significantly decrease their severity. The effectiveness of CTX should be prospectively compared with that of hydroxyurea and stem cell transplantation. 相似文献
973.
A Gupta AC Anand VSM ) Lt Col SK Chumber VK Sashindran SR Patrikar 《Medical Journal Armed Forces India》2007
Background: Use of protective footwear before entering the intensive care units is enforced with the assumption that it lowers the incidence of bacterial floor colonization. The present study was carried out to find the efficacy of protective footwear on bacterial floor colonization. 相似文献
974.
975.
976.
977.
Development of esophageal metaplasia and adenocarcinoma in a rat surgical model without the use of a carcinogen 总被引:16,自引:9,他引:16
Goldstein SR; Yang GY; Curtis SK; Reuhl KR; Liu BC; Mirvish SS; Newmark HL; Yang CS 《Carcinogenesis》1997,18(11):2265-2270
In order to establish an animal model for studying the cause and prevention
of esophageal adenocarcinoma (EAC) and its frequent precursor, Barrett's
esophagus (BE), factors affecting the pathogenic processes were
investigated in an esophagoduodenal anastomosis model with rats.
Experiments by us and others have shown that surgical treatment produced
reflux esophagitis with cell hyperproliferation, but not EAC. Additional
treatment with a carcinogen has been shown to be necessary for the
development of EAC, squamous cell carcinomas (SCC) or EAC/SCC mixtures. We
found that the surgically treated animals developed anemia due possibly to
reduced iron absorption. When the operated animals were supplemented with
iron, EAC occurred at a high rate (73%) after 30 weeks, and treatment with
N'-nitrosonornicotine did not enhance the rate of tumorigenesis. Treatment
with carcinogen, however, induced SCC in the group of rats killed after 22
weeks. The results suggest that iron overload, which is known to cause
oxidative damage, is an enhancing factor for adenocarcinogenesis. The
pathogenesis of EAC in the iron-supplemented, non-carcinogen treated group
resembles human esophageal adenocarcinogenesis in many features. All the BE
was the specialized type with goblet cells (containing sialomucin or
sulfomucin) and columnar cells (containing acid or neutral mucin) as well
as an incompletely developed brush border. Almost all of the BE was located
at the bottom of the esophagus and was continuous with the duodenal mucosa;
dysplasia became more frequent at later time points. All of the cancers
were well-differentiated mucinous EAC, and most of the EAC had an adjacent
area of BE with dysplasia. The results are consistent with the proposed
human sequence for pathogenic events of BE progression to 'BE with
dysplasia' and then to EAC. Esophagoduodenal anastomosis and iron treatment
in rats produces a high rate of BE and EAC which are morphologically
similar to human BE and EAC; this may be a useful animal model to study the
development and prevention of EAC in humans.
相似文献
978.
Effects of the carcinogen, acrylonitrile, on forestomach cell proliferation and apoptosis in the rat: comparison with methacrylonitrile 总被引:2,自引:0,他引:2
Acrylonitrile (AN) and methacrylonitrile (MAN) are two major industrial
nitriles used in the production of plastics and acrylic fibers. Whereas AN
is a potent acute toxin and carcinogenic in rats, little is known regarding
MAN. Current work is part of an overall effort designed to assess the
potential toxicity/carcinogenicity of MAN. The present study compares the
ability of the two chemicals to induce epithelial proliferation and
apoptosis in the forestomach (FS; a target of AN carcinogenicity), liver
and glandular stomach (non-targets of AN carcinogenicity) of male F344
rats. AN was administered to rats daily, by gavage, for 6 weeks, at 0.43
and 0.22 mmol/kg. MAN was administered at 0.87 and 0.43 mmol/kg. Both AN
and MAN induced a dose-dependent increase in epithelial cell proliferation
in the FS of male F344 rats as determined by bromodeoxyuridine (BrdU)
incorporation into DNA. In contrast, AN, but not MAN caused a
dose-dependent increase in the thickness of the forestomach squamous
mucosa. This increased thickness (hyperplasia) was reflected by an increase
in the number of total epithelial cells per unit length of mucosa. At doses
of AN and MAN which induced a 2.3-fold increase in BrdU incorporation,
apoptosis was 5- and 18-fold greater than controls, respectively. Although
both MAN and AN caused a similar increase in cell proliferation, the
relatively more prominent increase in the apoptotic index of the squamous
epithelium of rats exposed to MAN may explain the lack of a detectable
increase in the thickness of the mucosa compared to that seen with AN. The
disruption of the balance between FS mucosal cell proliferation and
apoptosis in favor of a net increase in the number of FS epithelial cells
per unit length may contribute to the carcinogenicity of AN. In conclusion,
present work demonstrated that AN selectively induced a net enhancement in
FS cell proliferation, a site of its carcinogenicity. On the other hand,
MAN-induced FS cell proliferation was associated with a parallel increase
in apoptosis. The relatively greater increase in apoptosis by MAN may have
compensated for the increase in FS mucosal cell proliferation and the lack
of observable change in the FS thickness.
相似文献
979.
980.
Fantz CR Powell C Karon B Parvin CA Hankins K Dayal M Sadovsky Y Johari V Apple FS Gronowski AM 《Clinical chemistry》2002,48(5):761-765
BACKGROUND: Because respiratory distress syndrome (RDS) affects 1% of live births, accurate and rapid assessment of markers of fetal lung maturity is critical to clinicians in deciding whether to deliver a preterm infant. Our objective was to determine the optimal diagnostic cutoff value for the TDx-FLM II assay (Abbott Laboratories) for predicting clinically significant RDS. METHODS: Amniotic fluid TDx-FLM II data were collected retrospectively over 4 years. Women were included in the study if they had delivered within 72 h of TDx-FLM II testing and both the mother and infant charts could be reviewed. Women who had been treated with steroids and delivered unaffected infants were excluded from the analysis. The diagnosis of RDS was defined as infants who either were treated with surfactant and/or were placed on a ventilator and/or required continuous positive airway pressure for >1 day. RESULTS: A total of 185 women met all entry criteria (15 RDS, 170 non-RDS). A cutoff value for a mature result of >or=45 mg/g gave a sensitivity of 100% (95% confidence interval, 82-100%) and a specificity of 90% (95% confidence interval, 78-89%). CONCLUSIONS: The TDx-FLM II appears to predict clinically significant RDS when a cutoff of >or=45 mg/g is used for mature results. Further studies will be required to confirm these findings. 相似文献