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21.
22.
The synthesis of poly(2,5-dialkoxy-p-phenylene)s (PPP) by palladium-catalyzed polycondensation of 2,5-dialkoxy-4-bromophenylboronic acids is described. Number-average degrees of polymerization of ca. 30 have been reached at best. The characterization of the polymers by NMR, IR, UV-VIS and fluorescence spectra, data on the bulk structure obtained by X-ray methods, melting behavior and thermal stability are reported. PPP's with long alkoxy side chains exhibit a layered phase structure, those with short or branched alkoxy side chains, cylindrical packing. Poly(2,5-dibutoxy-p-phenylene) was prepared with chain lengths 7 ≤ Pn ≤ 30. The polymer with Pn of 30 shows thermal transitions in the bulk phase at 182°C and 227°C. It forms an anisotropic melt above 227°C which only starts decomposing if heated above 300°C. The polymers of shorter chain length show isotropic melts, with the melting point strongly depending on chain length. 相似文献
23.
Debelenko LV; Brambilla E; Agarwal SK; Swalwell JI; Kester MB; Lubensky IA; Zhuang Z; Guru SC; Manickam P; Olufemi SE; Chandrasekharappa SC; Crabtree JS; Kim YS; Heppner C; Burns AL; Spiegel AM; Marx SJ; Liotta LA; Collins FS; Travis WD; Emmert-Buck MR 《Human molecular genetics》1997,6(13):2285-2290
Lung carcinoids occur sporadically and rarely in association with multiple
endocrine neoplasia type 1 (MEN1). There are no well defined genetic
abnormalities known to occur in these tumors. We studied 11 sporadic lung
carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene
on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy
fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was
studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene
were inactivated. All four tumors showed the presence of a MEN1 gene
mutation and loss of the other allele. Observed mutations included a 1 bp
insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide
substitution affecting a donor splice site. Each mutation predicts
truncation or potentially complete loss of menin. The remaining seven
tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH.
The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a
complex germline MEN1 gene mutation. The data implicate the MEN1 gene in
the pathogenesis of sporadic lung carcinoids, representing the first
defined genetic alteration in these tumors.
相似文献
24.
Determination of Dissolved Oxygen in Heterogenous Systems Particularly in Emulsions and Oily Liquids
Foiβner Karl-Heinz Leonhardt Andreas Wegner Gerhard Heinz Bauer Kurt 《Pharmaceutical research》1985,2(1):44-46
The content of dissolved oxygen was determined by four independent methods in a series of non-aqueous or heterogenous systems. The Lex-O2-Content Analyzer represents a fast and simple apparatus that employs a coulometric oxygen assay with Hersch cell detection. A comparison of the results with different methods demonstrates the reliability of the Lex-O2 in the determination of oxygen dissolved in heterogeneous or non-aqueous systems. Therefore, this apparatus can be recommended for the measurement of oxygen in oxygenator or perfusion fluids, as well as in blood substitutes or other oxygen transporting systems. 相似文献
25.
Layland Eric K. Caldwell Linda L. Ram Nilam Smith Edward A. Wegner Lisa Jacobs Joachim J. 《Prevention science》2022,23(7):1251-1263
Prevention Science - An earlier trial of a school-based, preventative intervention, HealthWise South Africa, demonstrated some efficacy in preventing adolescent drinking and smoking in the Western... 相似文献
26.
Layland Eric K. Ram Nilam Caldwell Linda L. Smith Edward A. Wegner Lisa 《Archives of sexual behavior》2021,50(6):2383-2394
Archives of Sexual Behavior - Sex during adolescence is normative; however, there are substantial individual differences in the timing and context of sexual debut. Leisure boredom is an... 相似文献
27.
Mentel R Bordihn N Wegner U Wendel H Niklasson B 《Medical microbiology and immunology》1999,188(1):51-53
Dobrava virus infection was diagnosed serologically by enzyme-linked immunosorbent and immunofluorescence assays. To determine
which hantavirus serotype was involved, sera were analyzed by a focus reduction neutralization test. The clinical data indicated
that only pulmonary manifestation was present. Our data support the presence of Dobrava virus infection outside the Balkan
region. In conclusion, a previously healthy adult with unexplained pulmonary perfusion failure should be investigated for
hantavirus infection.
Received: 15 March 1999 相似文献
28.
A prospective study of methylenetetrahydrofolate reductase and methionine synthase gene polymorphisms, and risk of colorectal adenoma 总被引:8,自引:2,他引:8
Chen J; Giovannucci E; Hankinson SE; Ma J; Willett WC; Spiegelman D; Kelsey KT; Hunter DJ 《Carcinogenesis》1998,19(12):2129-2132
We examined the relationship between a functional polymorphism (667C--
>T, ala-->val) of the methylenetetrahydrofolate reductase gene
(MTHFR) and the risk of colorectal adenomas in the prospective Nurses'
Health Study. Among 257 incident polyp cases and 713 controls, the MTHFR
val/val polymorphism [relative risk (RR) = 1.35, 95% confidence interval
(CI) 0.84-2.17] was not significantly associated with risk of adenomas.
This lack of association was observed for both small (RR = 1.36, 95% CI
0.76-2.45) and large (RR = 1.32, 95% CI 0.66-2.66) adenomas. Furthermore,
there was no significant interaction between this polymorphism and
consumption of either folate, methionine or alcohol. We also examined the
relationship of a newly identified polymorphism (asp919gly) of the
methionine synthase gene (MS) with the risk of colorectal adenomas in the
same population. The MS gly/gly polymorphism was also not significantly
associated with risk of colorectal adenomas (RR = 0.66, 95% CI 0.26-1.70).
These results, which need to be confirmed in other studies, suggest that
the MTHFR val/val polymorphism, which has been previously inversely
associated with risk of colorectal cancer, plays a role only in a late
stage (adenoma-- >carcinoma) of colorectal tumorigenesis, and/or may
protect against malignant transformation in the subset of benign adenomas,
which may progress to malignancy.
相似文献
29.
30.
Wiktoria Blaszczak Wojciech Barczak Anna Wegner Wojciech Golusinski Wiktoria Maria Suchorska 《Medical oncology (Northwood, London, England)》2017,34(4):60
Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of malignant tumours that affects over 500,000 patients per year. Treatment failure is generally due to the heterogeneity of these tumours and to the serious adverse effects associated with treatment. Immunological system impairment, which is common in HNSCC, further contributes to treatment failure by mediating tumour escape mechanisms. To date, the only clinically approved targeted therapy agent is cetuximab, a monoclonal antibody (mAb) that binds to, and inhibits, epidermal growth factor receptor, which is widely overexpressed in HNSCC. Cetuximab has been proven to induce antibody-dependent cellular cytotoxicity, further magnifying its therapeutic effect. DNA sequencing of HNSCC cells has identified the presence of mutated genes, thus making their protein products potential targets for therapeutic inhibition. Immune mechanisms have been found to have a significant impact on carcinogenesis, thus providing the rationale to support efforts to identify anticancer compounds with immunomodulatory properties. In the context of the rapid development of novel targeted agents, the aim of the present paper is to review our current understanding of HNSCC and to review the novel anticancer agents (mAbs and TKIs) introduced in recent years, including an assessment of their efficacy and mechanisms of action. 相似文献