全文获取类型
收费全文 | 14788篇 |
免费 | 1392篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 158篇 |
儿科学 | 482篇 |
妇产科学 | 307篇 |
基础医学 | 1852篇 |
口腔科学 | 328篇 |
临床医学 | 1797篇 |
内科学 | 2955篇 |
皮肤病学 | 246篇 |
神经病学 | 1400篇 |
特种医学 | 779篇 |
外科学 | 2035篇 |
综合类 | 300篇 |
一般理论 | 12篇 |
预防医学 | 1454篇 |
眼科学 | 311篇 |
药学 | 964篇 |
中国医学 | 15篇 |
肿瘤学 | 824篇 |
出版年
2021年 | 215篇 |
2020年 | 129篇 |
2019年 | 216篇 |
2018年 | 268篇 |
2017年 | 217篇 |
2016年 | 242篇 |
2015年 | 240篇 |
2014年 | 326篇 |
2013年 | 499篇 |
2012年 | 661篇 |
2011年 | 680篇 |
2010年 | 380篇 |
2009年 | 408篇 |
2008年 | 632篇 |
2007年 | 671篇 |
2006年 | 727篇 |
2005年 | 627篇 |
2004年 | 614篇 |
2003年 | 536篇 |
2002年 | 505篇 |
2001年 | 499篇 |
2000年 | 482篇 |
1999年 | 411篇 |
1998年 | 184篇 |
1997年 | 181篇 |
1996年 | 156篇 |
1995年 | 161篇 |
1994年 | 137篇 |
1993年 | 127篇 |
1992年 | 301篇 |
1991年 | 306篇 |
1990年 | 339篇 |
1989年 | 298篇 |
1988年 | 262篇 |
1987年 | 274篇 |
1986年 | 269篇 |
1985年 | 237篇 |
1984年 | 202篇 |
1983年 | 170篇 |
1982年 | 133篇 |
1981年 | 113篇 |
1980年 | 114篇 |
1979年 | 159篇 |
1978年 | 133篇 |
1977年 | 130篇 |
1976年 | 153篇 |
1975年 | 107篇 |
1974年 | 127篇 |
1972年 | 120篇 |
1970年 | 103篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Phillip Adams 《Genetic epidemiology》1994,11(1):87-98
Two programs have been developed to manage linkage analysis data. The first program, LABMAN, is a comprehensive laboratory data management system organizing pedigrees, blood DNA samples, DNA markers, Southern blot or polyacrylamide gels, autoradiographs, and marker-allele typings generated from these samples. Output includes mendelization checks for genetic incompatibilities in typings and formatted files ready for linkage analysis. LABMAN can also compress highly polymorphic allele systems into smaller allele systems facilitating analysis of large systems. The second program, LINKMAN, provides data management for lod score output from linkage analyses. It reads linkage analysis output files, calculates lod scores by family, associates lod scores with specific marker and family identifiers, and stores these data in a database where they can be combined with lod scores from previous analyses. LINKMAN easily incorporates any of a wide variety of genetic models. It produces formatted output of lod scores by user-specified criteria for reports or as ASCII files for input to other programs. If desired, tests of homogeneity of linkage across families can be run via the HOMOG program [Ott, 1991] and their output included in reports. The programs include features critical for conducting genome searches of complex diseases: They are easy-to-use, well-tested, and reliable. Data from multi-center investigations can be easily combined for analysis. Moreover, they include extensive error-checking capabilities, and they are specifically set up to protect blindness between laboratory workers and data analysts. LABMAN and LINKMAN are currently available free of charge under DOS. © 1994 Wiley-Liss, Inc. 相似文献
42.
Farzad Mostashari Annie Fine Debjani Das John Adams Marcelle Layton 《Journal of urban health》2003,80(1):i43-i49
In 1998, the New York City Department of Health and the Mayor’s Office of Emergency Management began monitoring the volume of ambulance dispatch calls as a surveillance tool for biologic terrorism. We adapted statistical techniques designed to measure excess influenza mortality and applied them to outbreak detection using ambulance dispatch data. Since 1999, we have been performing serial daily regressions to determine the alarm threshold for the current day. In this article, we evaluate this approach by simulating a series of 2,200 daily regressions. In the influenza detection implementation of this model, there were 71 (3.2%) alarms at the 99% level. Of these alarms, 64 (90%) occurred shortly before or during a period of peak influenza in each of six influenza seasons. In the bioterrorism detection implementation of this methodology, after accounting for current influenza activity, there were 24 (1.1%) alarms at the 99% level. Two occurred during a large snowstorm, 1 is unexplained, and 21 occurred shortly before or during a period of peak influenza activity in each of six influenza seasons. Our findings suggest that this surveillance system is sensitive to communitywide respiratory outbreaks with relatively few false alarms. More work needs to be done to evaluate the sensitivity of this approach for detecting nonrespiratory illness and more localized outbreaks. 相似文献
43.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
44.
Robert Reed MS Igor Grant MD Kenneth M Adams PhD 《Alcoholism, clinical and experimental research》1987,11(4):340-344
We examined the relationship of history of alcoholism in first-degree relatives to neuropsychological performance of alcoholics abstinent from several weeks to several years. Eighty-four men were assigned to four groups based on "strength" of family history of alcoholism. The groups were: (1) "strong history," a parent plus another first-degree relative positive; (2) "moderate," parent only positive; (3) "weak," nonparent first-degree relative only positive; and (4) "negative," no first-degree relative positive. There were no significant between-group differences in NP performance. In other analyses there were no NP differences between alcoholics classified positive or negative purely on basis of paternal alcoholism, and no differences between subjects who had multigenerational versus unigenerational versus negative familial histories of alcoholism. It is concluded that genetic loading for alcoholism does not significantly affect the NP status of abstinent alcoholic groups equated for education, drinking history, and medical risk. 相似文献
45.
46.
D J Doudet C A McLellan R Carson H R Adams H Miyake T G Aigner R T Finn R M Cohen 《Journal of cerebral blood flow and metabolism》1991,11(5):726-734
Most attempts to model accurately [18F]-DOPA imaging of the dopamine system are based on the assumptions that its main peripheral metabolite, 3-O-methyl-6-[18F]fluoro-L-DOPA ([18F]3-OM-DOPA), crosses the blood-brain barrier but is present as a homogenous distribution throughout the brain, in part because it is not converted into [18F]DOPA in significant quantities. These assumptions were based mainly on data in rodents. Little information is available in the primate. To verify the accuracy of the above assumptions, we administered 18F-labeled 3-OM-DOPA to normal rhesus monkeys and animals with lesions of the DA nigrostriatal system. No selective 18F regional accumulation in brain was apparent in normal or lesioned animals. The plasma metabolite analysis revealed that only the negatively charged metabolites (e.g., sulfated conjugates) that do not cross the blood-brain barrier were found in significant quantities in the plasma. A one-compartment, three-parameter model was adequate to describe the kinetics of [18F]3-OM-DOPA. In conclusion, assumptions concerning [18F]3-OM-DOPA's behavior in brain appear acceptable for [18F]DOPA modeling purposes. 相似文献
47.
48.
RGD peptides immobilized on a mechanically deformable surface promote osteoblast differentiation. 总被引:1,自引:0,他引:1
E A Cavalcanti-Adam I M Shapiro R J Composto E J Macarak C S Adams 《Journal of bone and mineral research》2002,17(12):2130-2140
The major objective of this work was to attach bone cells to a deformable surface for the effective transmission of force. We functionalized a silastic membrane and treated it with 3-aminopropyltriethoxysilane (APTS). A minimal RGD peptide was then covalently linked to the aminated surface. MC3T3-E1 osteoblast-like cells were cultured on the arginine-glycine-aspartic acid (RGD)-treated membrane for 3-15 days and cell attachment and proliferation was evaluated. We observed that cells were immediately bound to the membrane and proliferated. After 8 days on the material surface, osteoblasts exhibited high levels of ALP staining, indicating that the cells were undergoing maturation. Alizarin red staining and Fourier transform infrared (FTIR) analysis showed that the mineral formed by the cells was a biological apatite. The second objective was to apply a mechanical force to cells cultured on the modified silicone membrane. Dynamic equibiaxial strain, 2% magnitude, and a 0.25-Hz frequency were applied to bone cells for 2 h. Osteoblasts elicited increased phalloidin fluorescence, suggesting that there was reorganization of the cytoskeleton. Furthermore, the applied strain elicited increased expression of the alpha(v)beta3 integrin receptor. We concluded that the covalent binding of RGD peptides to a silicone membrane provides a compatible surface for the attachment and subsequent differentiation of osteoblasts. Moreover, the engineered surface transduces applied mechanical forces directly to the adherent cells via integrin receptors. 相似文献
49.
McConaghy (1989) argued that the validity of penile circumference responses (PCRs) is at best unestablished and that penile volume responses (PVRs) have been demonstrated to be clearly superior indices of sexual arousal and orientation. In his critique, McConaghy stated that (i) penile erection has been incorrectly identified with sexual arousal, (ii) that PCRs have not been shown to accurately discriminate between divergent patterns of sexual arousal (including paraphilias), (iii) that the methodologies used to compare the two types of transducers are inappropriate, and (iv) that PCRs should not be used for diagnostic and treatment decisions. In this paper, McConaghy's criticisms are reviewed in the context of the existing literature on the subject. Although PCRs and PVRs involve different methodologies, they generally yield results that bear more similarities than differences. Furthermore, there is an extensive and growing literature on the use of PCR measures with various paraphilias. Several of McConaghy's arguments should be considered tentative while others are clearly unsubstantiated. Most of McConaghy's concerns over the validity and uses of PCR measures are empirical questions. Suggestions for future research are offered. 相似文献
50.
D. Dickerson B. Adams G. Engelbrecht G. Boltman R. Hickman D. Kahn 《Transplant international》1992,5(Z1):S63-S64
The precise cause of allograft dysfunction after renal transplantation often cannot be established by non-invasive means. In clinical practice, radionuclide scans form an integral part of the clinician's armamentarium in the assessment of these patients [1, 2]. Unfortunately, in the clinical setting more than one pathological process may be responsible for the impaired function, making it difficult to correlate the scan appearances with the pathology. In this study in rats we compared the renal DTPA scan appearances of the various pathological processes which may cause renal allograft dysfunction in the immediate post-transplant period. 相似文献