全文获取类型
收费全文 | 1619篇 |
免费 | 118篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 45篇 |
妇产科学 | 23篇 |
基础医学 | 255篇 |
口腔科学 | 41篇 |
临床医学 | 80篇 |
内科学 | 329篇 |
皮肤病学 | 31篇 |
神经病学 | 49篇 |
特种医学 | 46篇 |
外国民族医学 | 1篇 |
外科学 | 286篇 |
综合类 | 24篇 |
一般理论 | 1篇 |
预防医学 | 107篇 |
眼科学 | 27篇 |
药学 | 169篇 |
中国医学 | 16篇 |
肿瘤学 | 205篇 |
出版年
2023年 | 8篇 |
2022年 | 33篇 |
2021年 | 64篇 |
2020年 | 40篇 |
2019年 | 53篇 |
2018年 | 96篇 |
2017年 | 63篇 |
2016年 | 58篇 |
2015年 | 47篇 |
2014年 | 72篇 |
2013年 | 96篇 |
2012年 | 119篇 |
2011年 | 125篇 |
2010年 | 66篇 |
2009年 | 64篇 |
2008年 | 94篇 |
2007年 | 81篇 |
2006年 | 88篇 |
2005年 | 70篇 |
2004年 | 65篇 |
2003年 | 54篇 |
2002年 | 45篇 |
2001年 | 27篇 |
2000年 | 31篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1970年 | 5篇 |
1969年 | 7篇 |
1967年 | 4篇 |
1965年 | 4篇 |
排序方式: 共有1747条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
A modified formulation of inhaled salbutamol and a new inhaler device were studied in a group of 11 moderate-to-severe asthmatic patients. Changes in airway calibre (FEV1, Vmax30) were measured before and after inhalation of the new formulation, and compared with changes following inhalation of conventional salbutamol. A standard Rotahaler was used as a reference for the new inhaler. The study was conducted as a two-part randomized, double-blind cross-over trial. We found a significantly greater bronchodilatation of the larger airways using the modified drug in the Rotahaler. The new inhaler did not show any superiority over the Rotahaler, contrary to expectations from in vitro work. A slightly shorter model may better reflect the in vitro results. The study has implications for inhalation therapy in general. 相似文献
5.
Not many data exist to guide us in the management of patients with chronic hepatitis B virus infection and “normal” alanine
aminotransferase levels. Many of these patients may not have normal levels on long-term follow-up or when the upper limit
of normal is determined from a truly healthy reference population. These patients may have significant histologic disease
and benefit from further investigation or treatment. This article focuses on the disease course of such patients. 相似文献
6.
M. Hřebíček K. Hodaňová J. Ledvinová J. Sokolová M. Elleder J. Zeman L. Vepřeková J. Musilová J. M. F. G. Aerts G. H. Renkema D. Hřebíček 《Virchows Archiv : an international journal of pathology》1996,428(4-5):305-309
We present a case of Merkel cell carcinoma of the thigh diagnosed by conventional histology, immunohistochemistry, electron microscopy and cytogenetics. A unique chromosome 6 trisomy characterized this primary neoplasm, as confirmed by FISH study. The role of chromosome analysis and interphase cytogenetics is emphasized as an adjunct in the subtyping of tumours and their prognostic evaluation. 相似文献
7.
Kveiborg M Kassem M Langdahl B Eriksen EF Clark BF Rattan SI 《Mechanisms of ageing and development》1999,106(3):261-271
We have compared the telomere length, as assessed by Southern analysis, of telomere restriction fragments (TRFs) generated by RsaI/HinfI digestion of genomic DNA in: (i) in vitro cultured human trabecular osteoblasts undergoing cellular aging; and (ii) peripheral blood leukocytes (PBL) obtained from three groups of women: young (aged 20-26 years, n = 15), elderly (aged 48-85 years, n = 15) and osteoporotic (aged 52-81 years, n = 14). The mean TRF length in human osteoblasts undergoing aging in vitro decreased from an average of 9.32 kilobasepairs (kb) in middle-aged cells to an average of 7.80 kb in old cells. The rate of TRF shortening was about 100 bp per population doubling, which is similar to what has been reported for other cell types, such as human fibroblasts. Furthermore, there was a 30% decline in the total amount of telomeric DNA in senescent osteoblasts as compared with young cells. In the case of PBL, TRF length in the DNA extracted from young women was slightly longer (6.76 +/- 0.64 kb) than that from a group of elderly women (6.42 +/- 0.71 kb). A comparison of TRFs in the DNA extracted from the PBL from osteoporotic patients and from age-matched controls did not show any significant differences (6.47 +/- 0.94 versus 6.42 +/- 0.71 kb, respectively). Therefore, using TRF length as a marker for cellular aging in vitro and in vivo, our data comparing TRFs from osteoporotic patients and age-matched controls do not support the notion of the occurrence of a generalized premature cellular aging in osteoporotic patients. 相似文献
8.
Quantitation of Ergosterol Content: Novel Method for Determination of Fluconazole Susceptibility of Candida albicans 下载免费PDF全文
Beth A. Arthington-Skaggs Hoda Jradi Tejal Desai Christine J. Morrison 《Journal of clinical microbiology》1999,37(10):3332-3337
MIC end points for the most commonly prescribed azole antifungal drug, fluconazole, can be difficult to determine because its fungistatic nature can lead to excessive "trailing" of growth during susceptibility testing by National Committee for Clinical Laboratory Standards broth macrodilution and microdilution methods. To overcome this ambiguity, and because fluconazole acts by inhibiting ergosterol biosynthesis, we developed a novel method to differentiate fluconazole-susceptible from fluconazole-resistant isolates by quantitating ergosterol production in cells grown in 0, 1, 4, 16, or 64 microg of fluconazole per ml. Ergosterol was isolated from whole yeast cells by saponification, followed by extraction of nonsaponifiable lipids with heptane. Ergosterol was identified by its unique spectrophotometric absorbance profile between 240 and 300 nm. We used this sterol quantitation method (SQM) to test 38 isolates with broth microdilution end points of =8 microg/ml (susceptible), 16 to 32 microg/ml (susceptible dose-dependent [SDD]), or >/=64 microg/ml (resistant) and 10 isolates with trailing end points by the broth microdilution method. No significant differences in mean ergosterol content were observed between any of the isolates grown in the absence of fluconazole. However, 18 susceptible isolates showed a mean reduction in ergosterol content of 72% after exposure to 1 microg of fluconazole/ml, an 84% reduction after exposure to 4 microg/ml, and 95 and 100% reductions after exposure to 16 and 64 microg of fluconazole/ml, respectively. Ten SDD isolates showed mean ergosterol reductions of 38, 57, 73, and 99% after exposure to 1, 4, 16, and 64 microg of fluconazole/ml, respectively. In contrast, 10 resistant isolates showed mean reductions in ergosterol content of only 25, 38, 53, and 84% after exposure to the same concentrations of fluconazole. The MIC of fluconazole, by using the SQM, was defined as the lowest concentration of the drug which resulted in 80% or greater inhibition of overall mean ergosterol biosynthesis compared to that in the drug-free control. Of 38 isolates which gave clear end points by the broth microdilution method, the SQM MIC was within 2 dilutions of the broth microdilution MIC for 33 (87%). The SQM also discriminated between resistant and highly resistant isolates and was particularly useful for discerning the fluconazole susceptibilities of 10 additional isolates which gave equivocal end points by the broth microdilution method due to trailing growth. In contrast to the broth microdilution method, the SQM determined trailing isolates to be susceptible rather than resistant, indicating that the SQM may predict clinical outcome more accurately. The SQM may provide a means to enhance current methods of fluconazole susceptibility testing and may provide a better correlation of in vitro with in vivo results, particularly for isolates with trailing end points. 相似文献
9.
Rivera M Merlin S Hoda RS Gopalan A Hoda SA 《International journal of surgical pathology》2004,12(4):301-306
Sentinel lymph node biopsy has attained "standard of care' status in the management of breast carcinoma. However, the pathological interpretation and clinical consequences of "minimally involved' sentinel lymph nodes remain controversial. Herein, we present some of the complex and challenging pathological problems inherent in this evolving setting. Clearly, at least some of our current concepts regarding "minimally involved' sentinel lymph nodes need reappraisal. 相似文献
10.
Meksem K Njiti VN Banz WJ Iqbal MJ Kassem MM Hyten DL Yuang J Winters TA Lightfoot DA 《Journal of biomedicine & biotechnology》2001,1(1):38-44
Soy products contain isoflavones (genistein, daidzein, andglycitein) that display biological effects when ingested byhumans and animals, these effects are species, dose and agedependent. Therefore, the content and quality of isoflavones insoybeans is a key to their biological effect. Our objective wasto identify loci that underlie isoflavone content in soybeanseeds. The study involved 100 recombinant inbred lines (RIL) fromthe cross of ‘Essex' by ‘Forrest,' two cultivars that contrastfor isoflavone content. Isoflavone content of seeds from each RILwas determined by high performance liquid chromatography (HPLC).The distribution of isoflavone content was continuous andunimodal. The heritability estimates on a line mean basis were79% for daidzein, 22% for genistein, and 88% for glycitein.Isoflavone content of soybean seeds was compared against 150polymorphic DNA markers in a one-way analysis of variance. Fourgenomic regions were found to be significantly associated withthe isoflavone content of soybean seeds across both locations andyears. Molecular linkage group B1 contained a major QTLunderlying glycitein content (P = 0.0001, R2 = 50.2%), linkagegroup N contained a QTL for glycitein (P = 0.0033, R2 = 11.1%)and a QTL for daidzein (P = 0.0023, R2 = 10.3%) and linkagegroup A1 contained a QTL for daidzein (P = 0.0081, R2 = 9.6%).Selection for these chromosomal regions in a marker assistedselection program will allow for the manipulation of amounts andprofiles of isoflavones (genistein, daidzein, and glycitein)content of soybean seeds. In addition, tightly linked markers canbe used in map based cloning of genes associated withisoflavone content. 相似文献