全文获取类型
收费全文 | 208013篇 |
免费 | 14719篇 |
国内免费 | 4236篇 |
专业分类
耳鼻咽喉 | 3033篇 |
儿科学 | 3596篇 |
妇产科学 | 4246篇 |
基础医学 | 30010篇 |
口腔科学 | 4291篇 |
临床医学 | 21169篇 |
内科学 | 38251篇 |
皮肤病学 | 4918篇 |
神经病学 | 14732篇 |
特种医学 | 10089篇 |
外国民族医学 | 21篇 |
外科学 | 26842篇 |
综合类 | 8394篇 |
现状与发展 | 18篇 |
一般理论 | 84篇 |
预防医学 | 12644篇 |
眼科学 | 5461篇 |
药学 | 18266篇 |
38篇 | |
中国医学 | 3894篇 |
肿瘤学 | 16971篇 |
出版年
2023年 | 1788篇 |
2022年 | 4668篇 |
2021年 | 7481篇 |
2020年 | 4466篇 |
2019年 | 5363篇 |
2018年 | 6160篇 |
2017年 | 4832篇 |
2016年 | 5677篇 |
2015年 | 7825篇 |
2014年 | 9459篇 |
2013年 | 10806篇 |
2012年 | 16088篇 |
2011年 | 16025篇 |
2010年 | 9614篇 |
2009年 | 7944篇 |
2008年 | 11653篇 |
2007年 | 11502篇 |
2006年 | 10653篇 |
2005年 | 10116篇 |
2004年 | 8679篇 |
2003年 | 7628篇 |
2002年 | 6600篇 |
2001年 | 5368篇 |
2000年 | 4990篇 |
1999年 | 4296篇 |
1998年 | 1898篇 |
1997年 | 1568篇 |
1996年 | 1410篇 |
1995年 | 1269篇 |
1994年 | 1118篇 |
1993年 | 846篇 |
1992年 | 1916篇 |
1991年 | 1830篇 |
1990年 | 1603篇 |
1989年 | 1467篇 |
1988年 | 1368篇 |
1987年 | 1214篇 |
1986年 | 1164篇 |
1985年 | 999篇 |
1984年 | 724篇 |
1983年 | 628篇 |
1982年 | 424篇 |
1981年 | 412篇 |
1980年 | 360篇 |
1979年 | 554篇 |
1978年 | 427篇 |
1977年 | 410篇 |
1976年 | 374篇 |
1974年 | 383篇 |
1973年 | 344篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
51.
W W Wong W J Cochran W J Klish E O Smith L S Lee M L Fiorotto P D Klein 《European journal of clinical nutrition》1988,42(3):233-242
We estimated body fat in 20 normal adults (10 males and 10 females) from 18O- and 2H-dilution spaces and from the equations of Durnin & Womersley and Pollock, Schmidt & Jackson based on skinfold thickness measurements. Differences between methods for body fat estimation were found to be sex-dependent: subsequent analyses indicated significant differences between methods within each sex. Regardless of sex, the highest fat estimates were obtained with the 18O-dilution method, followed by those obtained with the 2H-dilution method or the Durnin & Womersley equation. The lowest fat estimates were obtained using the Pollock, Schmidt & Jackson equation. The 18O-dilution method and the Durnin & Wormersley anthropometric method are both suitable and appropriate for body fat estimation in adults studied under field conditions. 相似文献
52.
M E Lee 《Journal of the American Optometric Association》1988,59(7):567-571
Beta adrenergic blocking agents have gained wide acceptance among practitioners and patients alike as extremely useful drugs for the treatment of open-angle glaucoma. This new class of antiglaucoma agents usually is effective in reducing elevated intraocular pressure and is generally well tolerated. This paper is intended to provide an understanding of the ophthalmic beta adrenergic blocking agents to optometrists who are actively involved in the treatment of glaucoma and/or in the monitoring of glaucoma patients. The clinical pharmacology of the three FDA-approved beta blockers -- timolol, levobunolol, and betaxolol, is evaluated and the drugs are compared. 相似文献
53.
In this new colorimetric assay for Factor XIII in plasma, 5-(biotinamido)pentylamine is used as the amine substrate. Factor XIII, a zymogen, is transformed by thrombin and Ca2+ to active Factor XIIIa, and the incorporation of 5-(biotinamido)pentylamine into N,N-dimethylcasein is used to measure catalytically active Factor XIIIa. The biotinylated enzymatic product is immobilized onto 96-well microtiter plates, complexed with streptavidin-beta-galactosidase, and the absorbance at 405 nm is monitored for production of p-nitrophenol from p-nitrophenyl-beta-D-galactopyranoside. Concentrations of N,N-dimethylcasein, 5-(biotinamido)pentylamine, Ca2+, and thrombin were chosen to allow near-maximum velocity of amine incorporation. A linear relationship was obtained between assay product and plasma volume, from 0.5 to 50 microL of plasma. Results correlated well (r greater than 0.924) with those from the most frequently utilized radiometric filter-paper assay for Factor XIII. The method appears to be ideal for routine diagnostic estimation of Factor XIII in plasma because of its simplicity, its lack of use of radioisotopes, and its potential for assay of large numbers of samples by use of microtiter plates and automated plate readers. 相似文献
54.
Jin Woo Kim M.D. Ho Shik Kim M.D. In Kyung Kim M.D. Mee Ran Kim M.D. Eun Young Cho B.S. Heung Kee Kim M.D. Joon Mo Lee M.D. Sung Eun Namkoong M.D. 《Gynecologic oncology》1998,69(3):230-236
Transforming growth factor-β1 (TGF-β1) is known to be a potent growth inhibitor for many cell types, including most epithelial cells. In skin keratinocytes, TGF-β1 has been shown to inhibit growth and to rapidly reduce c-mycexpression. However, the molecular mechanism of TGF-β1 action on cell growth of cervical carcinoma has not yet been elucidated. We thus assessed the effect of TGF-β1 on the growth of cervical carcinoma cell lines. Two cervical squamous carcinoma cell lines, CUMC-3 and CUMC-6, were incubated with varying concentrations of TGF-β1, and growth inhibition was evaluated with tetrazolium-based colorimetric assay. After culture in TGF-β1 for 24 h, inhibition of growth was detected in a dose-dependent manner at concentrations of 0.1–10 ng/ml in both cell lines. This effect of TGF-β1 on cultured carcinoma cells was associated with apoptotic process including oligonucleosomal ladder DNA and apoptotic body formations. Northern blot analysis revealed c-mycmRNA expression was suppressed by 10 ng/ml of TGF-β1 following 3 h of treatment in both cell lines. Western blot analysis showed that the level of p27Kip1protein was increased after TGF-β1 treatment in both cell lines. These results suggest that the mechanisms by which TGF-β1 inhibits the growth of cervical carcinoma are complex and may include effects on down-regulation of c-mycgene, and overexpression of p27Kip1protein. 相似文献
55.
The aim of this study was to evaluate if intraoperative vascular ultrasonography is of clinical value in the perioperative management of hepatic transplant patients. Fifteen intraoperative ultrasonographic examinations were performed on 13 patients (five female, eight male) during transplantation. These patients had clinically suspected vascular compromise. Among the 13 patients studied intraoperatively, five were correctly diagnosed as having hemodynamically significant vascular compromise. Of the intraoperative vascular sonographic examinations, the results of 13 were in concordance with the surgical impression as to whether further intervention was necessary or if the procedure could be terminated. Intraoperative sonography demonstrates potential to be of aid to the surgeon in recognition of vascular compromise. 相似文献
56.
Kevin G Becker Insong J Lee James W Nagle Rachel D Canning Ameer M Gado Rosarelis Torres Mihael H Polymeropoulos Paul T Massa WilliamE Biddison Paul D Drew 《International journal of developmental neuroscience》1997,15(7):73
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function. 相似文献
57.
58.
关于单结合胆红素水溶性的研究 总被引:4,自引:0,他引:4
目的:进一步研究单结合胆红素(MCB)的水难溶特性及其在病理性胆汁中参与胆红素沉淀和色素性结石形成的作用机制.方法:应用胆红素高效液相色谱分析技术,先从人胆汁中获得结合胆红素,再经分离、制备及纯化得到纯MCB.然后观察其水溶解度并与其它型胆红素比较.结果:在pH7.9,温度37℃接近生理的条件下,MCB的溶解度(558.25±5.96μm)仅为双结合胆红素(DCB)的1/7,比不结合胆红素(UCB)高约44倍并随pH值改变而呈曲线变化.pH7.9时最大;pH4.5时为0;而当pH>9时,反而低于呈离于状态的UCB.结论:MCB虽作为结合型胆红素在胆道生理条件下的不溶性明显高于UCB,但比DCB要低得多;而在胆道病理条件下,其水溶性不但远低于DCB,甚至还不如离子化的UCB,这可能是MCB参与胆红素沉淀及胆色素结石形成的理化基础. 相似文献
59.
60.
Twenty-eight patients participated prospectively in a study to evaluate the impact of hysteroscopically detected uterine and cervical anomalies on the success rate of ET in an IVF-ET program. All participants had a normal intrauterine cavity by standard HSG. All the patients had a diagnostic office hysteroscopy under paracervical block before commencing COH. Because our IVF program does not include hysteroscopy as a requirement before undergoing IVF and because the significance of mild intrauterine abnormalities is not yet known, the hysteroscopic findings were not relayed to the personnel involved in the IVF-ET procedure. Sixteen patients (group I) had a normal hysteroscopic evaluation. Twelve patients (group II) had abnormal hysteroscopic findings including small uterine septa, small submucous fibroids, uterine hypoplasia and cervical ridges. Although no difference in patients or cycle characteristics was present, there was a significant difference in the clinical PR between patients in groups I and II. In conclusion, in an IVF-ET program patients with normal hysterography but abnormal hysteroscopic findings had a significantly lower clinical PR, demonstrating the importance of performing hysteroscopy before IVF-ET. 相似文献