全文获取类型
收费全文 | 41093篇 |
免费 | 3319篇 |
国内免费 | 101篇 |
专业分类
耳鼻咽喉 | 508篇 |
儿科学 | 1226篇 |
妇产科学 | 844篇 |
基础医学 | 5256篇 |
口腔科学 | 637篇 |
临床医学 | 4353篇 |
内科学 | 8733篇 |
皮肤病学 | 618篇 |
神经病学 | 3930篇 |
特种医学 | 1703篇 |
外科学 | 6728篇 |
综合类 | 536篇 |
现状与发展 | 1篇 |
一般理论 | 63篇 |
预防医学 | 3408篇 |
眼科学 | 717篇 |
药学 | 2266篇 |
中国医学 | 52篇 |
肿瘤学 | 2934篇 |
出版年
2023年 | 362篇 |
2022年 | 630篇 |
2021年 | 1475篇 |
2020年 | 796篇 |
2019年 | 1186篇 |
2018年 | 1437篇 |
2017年 | 1023篇 |
2016年 | 1018篇 |
2015年 | 1187篇 |
2014年 | 1620篇 |
2013年 | 2073篇 |
2012年 | 2993篇 |
2011年 | 2946篇 |
2010年 | 1586篇 |
2009年 | 1346篇 |
2008年 | 2112篇 |
2007年 | 2221篇 |
2006年 | 2078篇 |
2005年 | 1871篇 |
2004年 | 1663篇 |
2003年 | 1424篇 |
2002年 | 1254篇 |
2001年 | 662篇 |
2000年 | 621篇 |
1999年 | 569篇 |
1998年 | 300篇 |
1997年 | 270篇 |
1996年 | 256篇 |
1995年 | 240篇 |
1994年 | 197篇 |
1993年 | 184篇 |
1992年 | 397篇 |
1991年 | 405篇 |
1990年 | 439篇 |
1989年 | 395篇 |
1988年 | 335篇 |
1987年 | 329篇 |
1986年 | 336篇 |
1985年 | 317篇 |
1984年 | 293篇 |
1983年 | 243篇 |
1982年 | 215篇 |
1981年 | 173篇 |
1980年 | 163篇 |
1979年 | 233篇 |
1978年 | 213篇 |
1977年 | 167篇 |
1976年 | 172篇 |
1974年 | 170篇 |
1972年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 36 毫秒
91.
Eleven "pure" borderlines, ten borderlines with depression, 16 "pure" depressives, and 31 normal subjects were compared on a number of standardized inventories of anxiety. While patient groups experienced more anxiety of all types than did normals, borderlines did not emerge as more anxious than other patient groups. Qualitative differences in the anxiety experienced by borderlines and nonborderlines are discussed. 相似文献
92.
Many studies have reported a decrease in visual field sensitivity as a function of increasing age in normal individuals. This age-related sensitivity loss has mainly been attributed to reductions in pupil size and transmission losses of the ocular media (particularly the lens), although neural losses in the retina, optic nerve and visual cortex have also been suggested. We evaluated the role of preretinal factors on normal visual field changes associated with aging. The central visual field of both eyes of 62 normal subjects (ages 20 to 72) were evaluated with Program 30-2 of a modified Humphrey Field Analyzer. Three test procedures were employed: (1) a standard visual field evaluation; (2) a yellow target on a yellow background condition (530 nm cutoff filter) to minimize the influence of lens transmission losses with age; and (3) a large target/high background luminance "yellow on yellow" test condition (530 nm cutoff filter, 635 asb background, Size V target) to minimize both pupil size and lens effects on central visual field sensitivity. In addition, relative lens absorption estimates were obtained for each subject. All three test conditions revealed a loss in visual field sensitivity with increasing age (approximately 0.8 dB per decade) but no meaningful differences were found among the three test procedures. Relative lens density increased with age but was not related to visual field sensitivity for any of the three test conditions. These data suggest that normal age-related visual field sensitivity changes are primarily due to neural losses rather than preretinal factors. 相似文献
93.
Mosaic ring 12p and total anomalous pulmonary venous return 总被引:1,自引:0,他引:1
Harris DL Siu BL Hummel M Harbert K Senft J Sargent L Wenger SL 《American journal of medical genetics. Part A》2004,131(1):91-93
An infant born with total anomalous pulmonary venous return (TAPVR) was found to have an extra chromosome present as a small ring. Spectral karyotyping and FISH analysis identified the material as a duplication involving the short arm of chromosome 12. Previous cases describing a variety of cytogenetic abnormalities that have been associated with TAPVR are reviewed along with prior cases of duplication 12p with their associated findings. We believe ours is the first case to report the occurrence of mosaic ring 12p and its association with TAPVR. 相似文献
94.
95.
Developmental Progression in Children's Knowledge of AIDS: Implications for Education and Attitudinal Change 总被引:1,自引:1,他引:1
Osborne Mary L.; Kistner Janet A.; Helgemo Benjamin 《Journal of pediatric psychology》1993,18(2):177-192
The effectiveness of curricula designed to enhance a child'sunderstanding of AIDS may hinge partially upon incorporatinginformation adjusted to the child's developmental status. Accordingly,we examined the developmental progression of children's understandingof illness transmission in general and AIDS in particular, aswell as explored the relation between a child's knowledge ofAIDS and his/her attitudes toward persons with AIDS. Knowledgeof AIDS was manipulated through use of a brief educational intervention.Results support a developmental progression in knowledge aboutAIDS that is consistent with progressions related to illnessesin general. Knowledge enhancement was associated with positivechanges in attitude. 相似文献
96.
Thomas Adams William S. Spielman Kenneth R. Holmes S. R. Heisey Michael M. Chen 《Annals of biomedical engineering》1985,13(3-4):237-258
The kidney, with its heterogeneous regional perfusion in the two anatomically and functionally distinct vascular beds of the
renal cortex and medulla, and with its nonuniform blood vessel geometries, presents a unique challenge for measuring intrarenal
blood flow distribution. Determining whole organ perfusion, on the other hand, is comparatively simple for the kidney, but
it provides relatively little information about the suspected dependency of renal excretory function on local perfusion rate.
Among the variety of methods proposed for gauging regional renal blood flow, some depend on measuring one or more of the tissue's
thermal properties. The most straightforward, but least reliable, involve measurements either of focal tissue temperature
alone, or of regional tissue thermal gradients. Simply using heat as a diffusible indicator, however, is unreliable as a measure
of blood flow, for many of the same reasons that using an inert gas in a dilution technique is unreliable. Recently developed
thermal analytical methods, though, hold promise for measuring local tissue blood flow with accuracy and precision. Two of
them are reviewed here. One depends on measurement of the effective thermal conductivity of a small mass of tissue by evaluating
the steady state ratio between regional unidirectional heat flux across it and the associated temperature gradient in one
vector along a segment of it through an imposed spheroidal heat field. The other depends on analyses of tissue temperature
decay subsequent to a controlled pulse of heat delivered through a small inserted thermistor bead. Both techniques use bioheat
transfer equations to deduce regional blood flow
Research by K.R. Holmes and M.M. Chen was supproted by NIH-NHLBI Grant HL27011, that by T. Adams and S.R. Heisey through the
Michigan Heart Association, and that by W.S. Spielman through a grant from the NSF (PCM 8110588) who is a recipient of NIH
Research Career Development Award HL01010. 相似文献
97.
Primm BJ Perez L Dennis GC Benjamin L Clark W Keough K Leak WD Payne R Smith D Sullivan LW;National Medical Association 《Journal of the National Medical Association》2004,96(9):1152-1161
ISSUE: Inadequate pain management is a serious public health problem that affects a wide cross-section of Americans. Patients are often denied sufficient medication, because physicians lack training and fear scrutiny from federal and state regulatory agencies. In addition, even the state-financed system of care, Medicaid, has been increasingly denying payment for the best treatment for pain management. These factors are complicated by physician bias about various subgroups and poor physician-patient communication. Comprehensive patient assessment plays a crucial role in determining appropriate treatment and identifying potential abuse problems. Physicians must routinely document medications analgesic effects and screen for potential ill effects and drug abuse. OBJECTIVE: To examine the prevalence of the undertreatment of pain, particularly among African Americans, and to recommend relevant proactive policy and practice changes to aid in eliminating this health problem. CONSENSUS PROCESS: In July 2002, the NMA convened the "Managing Pain: The Challenge in Underserved Populations: Appropriate Use versus Abuse and Diversion" Consensus Meeting in Washington, DC. The country's most renowned experts in the area of pain management and substance abuse reviewed substantial information regarding pain management and substance abuse including the following: --A draft summary paper on pain management and substance abuse that served as briefing material for consensus members; --Annotated bibliographies; --Articles on pain management and substance abuse; and --Key presentations on pain management and substance abuse. 相似文献
98.
Michael A Tangrea Rodrigo F Chuaqui John W Gillespie Mamoun Ahram Gallya Gannot Benjamin S Wallis Carolyn J M Best W Marston Linehan Lance A Liotta Thomas J Pohida Robert F Bonner Michael R Emmert-Buck 《Diagnostic molecular pathology》2004,13(4):207-212
Tissue microdissection is an important method for the study of disease states. However, it is difficult to perform high-throughput molecular analysis with current techniques. We describe here a prototype version of a novel technique (expression microdissection) that allows for the procurement of desired cells via molecular targeting. Expression microdissection (xMD) offers significant advantages over available methods, including an increase in dissection speed of several orders of magnitude. xMD may become a valuable tool for investigators studying cancer or other disease states in patient specimens and animal models. 相似文献
99.
100.
Adams AK Talman EA Campbell L McIlroy BK Moore MA 《Journal of biomedical materials research》2001,57(4):582-587
Bovine pericardial and porcine valve materials stabilized by dye-mediated photooxidation have shown potential for bioprosthetic valve use. Previously, in vitro and in vivo stability of these materials was demonstrated through enzymatic, chemical, extraction, rat subcutaneous, and functional challenges. Here, we examine the stability of photooxidized porcine aortic valves through amino acid, crosslink, and hydrothermal isometric tension analysis. Photooxidation reduced intact histidine residues from 17.0 to 0 residues per 1000, indicating the photooxidative alteration of this amino acid. Diphenyl borinic acid-derivitized hydrolyzates of proteins were separated by high-performance liquid chromatography, which identified several amino acid crosslinks that appeared with photooxidation that were absent in untreated controls. Thermal relaxation analysis indicated a significantly higher (p < 0.0002) thermal stability for photooxidized porcine cusps than that of untreated controls, with mean relaxation times for untreated cusps of 14,000 +/- 4650 versus 22,900 +/- 2480 s for photooxidized cusps. In summary, porcine aortic valve tissue treated by dye-mediated photooxidation contains new chemical species and exhibits properties consistent with intermolecular crosslink formation, which explain the increased biostability of this material and its potential for use in bioprosthetic devices. 相似文献