全文获取类型
收费全文 | 10398篇 |
免费 | 509篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 175篇 |
儿科学 | 224篇 |
妇产科学 | 184篇 |
基础医学 | 1748篇 |
口腔科学 | 227篇 |
临床医学 | 838篇 |
内科学 | 2056篇 |
皮肤病学 | 183篇 |
神经病学 | 1037篇 |
特种医学 | 653篇 |
外国民族医学 | 1篇 |
外科学 | 1259篇 |
综合类 | 73篇 |
预防医学 | 429篇 |
眼科学 | 254篇 |
药学 | 999篇 |
中国医学 | 64篇 |
肿瘤学 | 538篇 |
出版年
2022年 | 56篇 |
2021年 | 136篇 |
2020年 | 87篇 |
2019年 | 113篇 |
2018年 | 146篇 |
2017年 | 125篇 |
2016年 | 168篇 |
2015年 | 226篇 |
2014年 | 289篇 |
2013年 | 395篇 |
2012年 | 545篇 |
2011年 | 596篇 |
2010年 | 349篇 |
2009年 | 360篇 |
2008年 | 607篇 |
2007年 | 660篇 |
2006年 | 614篇 |
2005年 | 634篇 |
2004年 | 629篇 |
2003年 | 612篇 |
2002年 | 597篇 |
2001年 | 132篇 |
2000年 | 115篇 |
1999年 | 141篇 |
1998年 | 139篇 |
1997年 | 127篇 |
1996年 | 101篇 |
1995年 | 87篇 |
1994年 | 90篇 |
1993年 | 100篇 |
1992年 | 82篇 |
1991年 | 65篇 |
1990年 | 58篇 |
1989年 | 80篇 |
1988年 | 61篇 |
1987年 | 62篇 |
1986年 | 47篇 |
1985年 | 69篇 |
1984年 | 60篇 |
1983年 | 57篇 |
1982年 | 59篇 |
1981年 | 68篇 |
1980年 | 48篇 |
1979年 | 52篇 |
1978年 | 45篇 |
1977年 | 62篇 |
1976年 | 44篇 |
1975年 | 45篇 |
1973年 | 35篇 |
1963年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Thomas Abel William C. Cockerham Guenther Lueschen Gerhard Kunz 《Social science & medicine (1982)》1989,28(12):1269-1274
This paper examines whether American males with a high degree of control over their work situation pursue healthy lifestyles and rate their physical health more positively than those who score low on occupational self-direction. That is, are persons who control their work more likely to also try to control their health through living in a particularly healthy manner? We found that there was no support for a spillover effect from high occupational self-direction to enhanced participation in health lifestyles or more positive self-rated health. The findings suggest health lifestyles have spread throughout occupational work groups in the U.S. and support research that maintains such lifestyles have spread across social strata in America. 相似文献
22.
Daniel J. Weisdorf Martin M. Oken Gerhard J. Johnson Robert E. Rydell 《American journal of hematology》1981,11(4):397-402
Twenty-five patients with refractory anemia with excess blasts (RAEB) were studied. Five of these patients showed Auer rods in their myeloblasts, but met other criteria for RAEB. Median survival of the Auer rod-positive group was 14 months (range 2–27) from diagnosis with survival of 7 months after Auer rods were first observed. Median survival for the Auer rod-negative group was 12 months. Two patients developed overt acute leukemia, both from the Auer rod-negative group. The clinical course of Auer rod-positive RAEB, like that of Auer rod-negative RAEB, was one of progressive bone marrow failure complicated by infection, serious bleeding and the development of absolute transfusion requirement. These findings suggest that Auer rod-positive RAEB is a morphologic variant dysmyelopoietic syndrome that may pursue a similar clinical course to Auer rod-negative disease. Formulation of a separate treatment approach for those RAEB patients who possess Auer rods would appear ill advised. 相似文献
23.
Mario Leclerc Francisco Martinez Diaz Gerhard Wegner 《Macromolecular chemistry and physics.》1989,190(12):3105-3116
Poly(3-hexylthiophene) (PT6), poly(3-octylthiophene) (PT8), poly(3-decylthiophene) (PT10) and poly(3-dodecylthiophene) (PT12) were synthesized by electrochemical and chemical polymerization. Investigation of these polymers by means of gel permeation chromatography indicates that the polymers prepared from the different monomers under similar conditions do not differ substantially considering molecular weight and molecular weight distribution. Bimodal distributions were found for electropolymerized polymers, and with increasing polymerization time, the high-molecular-weight and probably highly branched fraction increased relatively to the low-molecular-weight fraction. The microstructure of the polymers was investigated by nuclear magnetic resonance, and it has been found that the polymers exhibit more types of structural units than expected from a simple coupling of adjacent thiophene moieties in 2,5′-positions. Chemical oxidation with iron trichloride in chloroform gave soluble, high-molecular-weight poly(3-alkyl-thiophene)s with a rather low amount of irregular couplings, and these more regular polymers exhibited a higher degree of crytallinity. Room temperature conductivities of the oxidized polymers were between 0,1 and 30 S/cm depending on the polymerization conditions, but these values were rather independent of the length of the alkyl substituent. 相似文献
24.
HLA-DR7 predicts the response to alkylating agents in steroid-sensitive nephrotic syndrome 总被引:2,自引:0,他引:2
Martin Konrad Joannis Mytilineos Hans Ruder Gerhard Opelz Karl Schärer 《Pediatric nephrology (Berlin, Germany)》1997,11(1):16-19
There is a lack of reliable predictors of the response to alkylating agents in children with idiopathic nephrotic syndrome
(NS). HLA-DR7 is strongly associated with the frequency of relapses in steroid-sensitive NS before cytostatic therapy. We
therefore examined retrospectively the time to the first relapse and the incidence of subsequent relapses in 54 HLA-typed
children with frequently relapsing NS, after treatment with cyclophosphamide (n = 49) or chlorambucil (n = 5) for 8 or 12 weeks; 38 patients were HLA-DR7 positive and 16 negative with 80% in both groups being steroid dependent.
HLA typing was performed using serological or DNA typing methods. Renal biopsy showed minimal glomerular changes. A lower
proportion of HLA-DR7 positive than negative patients remained in remission after 3 years (36% vs. 81%, P<0.02) and 5 years (36% vs. 72%, P<0.03). In the first 3 years after cytostatic therapy the mean number of prednisone-treated relapses was 1.3/patient per year
in HLA-DR7-positive patients compared with 0.4 in negative patients (P<0.025). There was no statistically significant difference in the proportion of relapse-free patients with and without steroid
dependency. The HLA status predicts the response of NS patients to alkylating agents better than the rate of previous relapses.
Received September 19, 1995; received in revised form and accepted April 16, 1996 相似文献
25.
Gerhard Adam Jrg Neuerburg Elmar Spüntrup Andreas Mühler Kira Scherer Vet Surg Rolf W. Günther 《Journal of magnetic resonance imaging : JMRI》1994,4(3):462-466
Gadolinium-DTPA (diethylenetriaminepentaacetic acid)-cascade-polymer, a potential new blood pool contrast agent for magnetic resonance (MR) imaging, was compared with a known blood pool agent, Gd-DTPA-polylysine, in an animal model. The relative signal intensities of liver, renal cortex, pancreas, and trunk muscle were assessed in 12 pigs between 4 seconds and 120 minutes after injection of a 20 μmol/kg dose of each contrast agent, by using a FLASH (fast low-angle shot) sequence. Except for muscle, all tissues showed visible enhancement after injection of either contrast agent. After injection of Gd-DTPA-polymer, enhancement patterns in the liver, renal cortex, and pancreas were similar to those seen after injection of Gd-DTPA-polylysine. No statistically significant differences in enhancement between the two contrast agents were found at any time point. The authors conclude that the contrast kinetics of Gd-DTPA-cascade-polymer are similar to those of Gd-DTPA-polylysine and that this agent may also be used as a blood pool contrast agent for MR imaging. 相似文献
26.
Pieternel C. M. Pasker de Jong Mary P. H. Berns Yvonne T. H. P. van Duynhoven Wies S. Nijdam Tom K. A. B. Eskes Gerhard A. Zielhuis 《Pharmacoepidemiology and drug safety》1995,4(1):23-30
Objective — To study the validity and accuracy of an adjusted questionnaire on medical drug use during pregnancy eight years after the pregnancy. Methods — The ability of a questionnaire on medication during pregnancy to detect actual use (= sensitivity) was tested against information collected 8 years previously (in 1983–1984) from 473 women with high-risk pregnancies who delivered at the University Hospital Nijmegen, the Netherlands. Results — For separate drug groups, the sensitivity varied between 5% and 91%. The timing of use was recalled moderately well. Although specific questions on drug groups did improve the sensitivity as compared to an earlier questionnaire, the improvement was not enough to make the questionnaire valid. High maternal education, low birth weight, low gestational age and a low 5-min Apgar score were related to better recall. The sensitivity of the questionnaire depended on the behavioural score of the child, implying recall bias. Conclusion — Questionnaire data on drug use during pregnancy obtained eight years after delivery are not a valid source of information. 相似文献
27.
Eberhard Henze Gerhard Graf Malte Clausen Bertram Rail Rolf Weller Dieter Derichs Joachim Kreidler Peter Heidenreich F. Sitzmann Willi Ernst Adam 《European journal of nuclear medicine and molecular imaging》1990,16(2):97-101
The exact regional correlation of findings of facial bone scans, planar or SPECT, to dental orthopan X-ray films (OPT) is difficult because of the very different projection techniques. To improve correlative imaging in this regard a projection algorithm was developed that uses SPECT data of the skull for reconstructing an orthopan tomoscintigraphic projection. Fourteen conventional SPECT slices of the upper and lower jaws were obtained during bone scanning. All mandibular slices were superimposed resulting in a horseshoe shaped structure, which was marked by an ROI which was divided into segments. All 14 SPECT slices were then masked by this segmental ROI, thereby marking the teeth-carrying bone in all slices. The information from this horseshoe like ROI is then transformed into lines. Line by line arrangement results in an orthopan projection, the orthopan tomoscintigram. This new display allows 1:1 true scale superimposition with the X-ray OPT and markedly facilitates correlative imaging. 相似文献
28.
Mobilization and evolutionary history of miniature inverted-repeat transposable elements (MITEs) in Beta vulgaris L. 总被引:1,自引:0,他引:1
Gerhard Menzel Daryna Dechyeva Heiko Keller Cornelia Lange Heinz Himmelbauer Thomas Schmidt 《Chromosome research》2006,14(8):831-844
We have identified three families of miniature inverted-repeat transposable elements (VulMITEs) in the genome of sugar beet
(Beta vulgaris L.), evidently derived from a member of the Vulmar family of mariner transposons. While VulMITEs I are typical stowaway-like MITEs, VulMITEs II and VulMITEs III are rearranged stowaway elements of increased size. The integration of divergent moderately and highly repetitive sequences into VulMITEs II and,
in particular in VulMITEs III, respectively, shows that amplification of repetitive DNA by MITEs contribute to the increase
of genome size with possible implications for plant genome evolution. Fluorescent in-situ hybridization (FISH), for the first time visualizing stowaway MITE distribution on plant chromosomes, revealed a dispersed localization of VulMITEs along all B. vulgaris chromosomes. Analysis of the flanking sequences identified a dispersed repeat as target site for the integration of the stowaway element VulMITE I. Recent transposition of VulMITE I, which most likely occurred during the domestication of cultivated beets, was concluded from insertional polymorphisms between
different B. vulgaris cultivars and species.
†Sequence data from this article have been deposited in the EMBL/GenBank Data Library under the accession nos. AM231630-AM231653
and AM259123-AM259125. 相似文献
29.
Gero Puhl Peter Olschewski Wenzel Sch?ning Gerhard Hunold Hans-Georg Liesaus Robert Winkler Ulf P Neumann Thomas E O Schubert Volker Schmitz Peter Neuhaus 《Liver transplantation》2006,12(12):1841-1849
Adequate flushing for liver donation requires large fluid volumes delivered at a high flow. This can be achieved more effectively with crystalloid solutions than with colloid-based solutions. This study examined the combination of initial histidine-tryptophan-ketoglutarate solution (HTK) graft flush and subsequent storage in University of Wisconsin solution (UW) to that of the single use of each solution. Livers from inbred Wistar rats were procured using aortic perfusion with UW or HTK for initial perfusion and reflushed after 30 minutes using either solution. In a third group, after perfusion with HTK, organs were reflushed with UW. A 60-minute in-vitro recirculating perfusion was performed after 24 hours of cold storage in the subsequent solution, as well as allotransplantation after 18 and 24 hours of cold storage. In extracorporeal perfusion, the HTK flush followed by UW storage was superior compared to the single use of either UW or HTK solution, as measured by portal venous pressure, bile flow, liver enzymes released into the effluent perfusate, glycerol leakage, and histological examinations. These data were consistent with the transplantation study. Histological damage and enzyme release after 5-day survival were lowest in the HTK flush and subsequent UW storage groups following 18 hours of cold storage; likewise, the 5-day survival was superior following 24 hours of cold storage. In conclusion, the combined use of HTK solution for initial graft rinse and subsequent storage in UW solution resulted in a cumulative protection. Choosing low-viscosity HTK solution for the initial organ flush may represent a feasible improvement in liver preservation, which also further reduces the required amount of UW solution. 相似文献
30.
Priv.-Doz. Dr. Arndt Klocke Bärbel Kahl-Nieke Gerhard Adam Jörn Kemper 《Journal of orofacial orthopedics》2006,67(6):424-429
BACKGROUND: In a previous investigation we reported on magnetic forces in the static magnetic field of a 1.5 Tesla MRI system. The aim of the present investigation was to assess forces on orthodontic wires in a high field strength MRI system at 3 Tesla. MATERIALS AND METHODS: Thirty-two different orthodontic wires (21 archwires, eight ligature wires and three retainer wires) were investigated in a 3 Tesla high field strength MRI system (Intera, Philips Medical Systems, Best, The Netherlands). Translational forces were measured by the deflection angle test (ASTM F2052-02), and rotational forces assessed on a 5-point qualitative scale. RESULTS AND CONCLUSION: Translational forces ranged between 43.5 mN and 136.1 mN for retainer wires and between 0.6 mN (Noninium) and 208.4 mN (Orthos Stainless Steel) for steel archwires. Translational forces were up to 53.8 times as high as gravitational forces for retainer wires and up to 54.5 times as high for steel archwires, associated with marked rotational forces for the most part. Archwires manufactured from nickel-titanium, titanium-molybdenum and cobalt-chromium and different ligature wires showed no or negligible forces in the magnetic field. Carefully ligated wires should not present a risk due to translational and rotational forces in the high field MRI system at 3 Tesla. 相似文献