全文获取类型
收费全文 | 23081篇 |
免费 | 1506篇 |
国内免费 | 100篇 |
专业分类
耳鼻咽喉 | 303篇 |
儿科学 | 624篇 |
妇产科学 | 674篇 |
基础医学 | 3685篇 |
口腔科学 | 335篇 |
临床医学 | 2182篇 |
内科学 | 4420篇 |
皮肤病学 | 600篇 |
神经病学 | 2290篇 |
特种医学 | 1252篇 |
外国民族医学 | 8篇 |
外科学 | 3257篇 |
综合类 | 186篇 |
一般理论 | 11篇 |
预防医学 | 1527篇 |
眼科学 | 552篇 |
药学 | 1571篇 |
中国医学 | 59篇 |
肿瘤学 | 1151篇 |
出版年
2022年 | 170篇 |
2021年 | 330篇 |
2020年 | 227篇 |
2019年 | 308篇 |
2018年 | 395篇 |
2017年 | 318篇 |
2016年 | 435篇 |
2015年 | 437篇 |
2014年 | 544篇 |
2013年 | 658篇 |
2012年 | 1061篇 |
2011年 | 1115篇 |
2010年 | 621篇 |
2009年 | 591篇 |
2008年 | 896篇 |
2007年 | 990篇 |
2006年 | 994篇 |
2005年 | 973篇 |
2004年 | 890篇 |
2003年 | 837篇 |
2002年 | 822篇 |
2001年 | 794篇 |
2000年 | 713篇 |
1999年 | 669篇 |
1998年 | 300篇 |
1997年 | 244篇 |
1996年 | 207篇 |
1995年 | 202篇 |
1994年 | 170篇 |
1993年 | 176篇 |
1992年 | 391篇 |
1991年 | 375篇 |
1990年 | 411篇 |
1989年 | 379篇 |
1988年 | 346篇 |
1987年 | 389篇 |
1986年 | 344篇 |
1985年 | 340篇 |
1984年 | 257篇 |
1983年 | 207篇 |
1979年 | 252篇 |
1978年 | 205篇 |
1977年 | 180篇 |
1975年 | 164篇 |
1974年 | 185篇 |
1973年 | 181篇 |
1972年 | 212篇 |
1971年 | 188篇 |
1969年 | 169篇 |
1967年 | 169篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Dr. J. Schmidt 《Archives of orthopaedic and trauma surgery》1993,112(2):79-81
Summary The principle of prebending plates is recommended for intertrochanteric osteotomies to reach satisfactory primary stability. This can be done by conventional or functional prebending. Because of the shape of an overbent plate in conventional prebending, when the tension device is used a sliding of the medial wedge of the proximal fragment medially on the distal osteotomy plane takes place. In functional prebending, the final shape of the plate results in almost no movement of the bone fragments. Therefore the measurable interfragmentary compression of functional prebending is better than in the conventional procedure. The functional prebending also causes no loss of primary installed medialisation and there is no need for an additional- procedure for the prebending during the operation. 相似文献
132.
Schmidt S.; Giessel R.; Bergis K. H.; Strojek K.; Grzeszczak W.; Ganten D.; Ritz E.; the Diabetic Nephropathy Study Group 《Nephrology, dialysis, transplantation》1996,11(9):1755-1761
BACKGROUND.: There is agreement that a family history of hypertension (HT),is a predictor for the risk of diabetic nephropathy (DN) inpatients with type 2 diabetes, and possibly also type 1 diabetes.It follows that genes related to the risk of hypertension mustalso be considered candidate genes for DN. The 235T allele ofthe angiotensinogen gene was found to be related to primaryHT. METHODS.: To examine whether it is predictive for DN as well, we examinedthe angiotensinogen gene polymorphism in 230 healthy local controls,423 patients with type 1 diabetes (n=180 with DN; n=243 withoutDN) and 663 patients with type 2 diabetes (n=310 with DN; n=353without DN). The angiotensinogen gene M235T polymorphism wasdetermined using PCR amplification. RESULTS.: The following results were obtained (i) no significant differenceof genotype distribution (type 1: MM/MT/TT(%) 27.6/57.2/15.2vs. 27.2/56.1/16.7 (P=0.92); type 2: MM/MT/TT (%) 31.7/48.2/20.1vs. 32.9/46.8/20.3 (P=0.93)) or allele frequencies (type 1:M 0.56 vs. 0.55 (P=0.795); type 2: M 0.56 vs. 0.56 (P=0.86))was found, between diabetic patients with or without DN, (ii)no difference was found between normotensive and hypertensivediabetic patients. CONCLUSION.: The data argue against a role of the angiotensinogen gene M235Tpolymorphism in the manifestation of diabetic nephropathy orhypertension in diabetic patients. 相似文献
133.
134.
Hepatitis has been considered, classically, as a diffuse hepatocellular necrosis, and little attention has been paid to the relationship of lesions to the microvasculature. In livers of mice (Balbc/J) infected with murine hepatitis virus (MHV-3), microcorrosion casts showed spherical cavities where casting compound was unable to fill sinusoids. At 48 hr postinfection such "lesions" had a mean diameter of 83 micron +/- 26 (SD) and their number/mm2 (at the surface of casts) was 0.95 +/- 1.3. Blind-ended sinusoids formed a distinct boundary between perfused and nonperfused areas, and concave impressions at their ends indicated cells blocking the lumen. In vivo microscopy of transilluminated livers in infected mice showed localized rounded areas without flow, corresponding to lesions seen in casts. RBC velocity measurements in sinusoids adjacent to lesions demonstrated that velocities fall from normal values to zero over a narrow border zone. Beginning with the most proximal sinusoid with visible flow and moving outward from the lesion to the second and third sinusoids, mean RBC velocities (micron/sec, +/- SD) were 17.4 +/- 6.7, 33.9 +/- 8.7, 66.6 +/- 27.3, respectively; this last value was not significantly different from velocities in normal liver (69.2 +/- 30.6). Transmission electron microscopy of livers of infected mice confirmed the presence of sinusoidal lumens blocked by protruding lining cells, RBCs, platelets, swollen hepatocytes, and cellular debris. This study demonstrates that the lesions are focal in origin, microvascular blockage leading to gradually increasing necrosis in all directions. 相似文献
135.
We have videorecorded spontaneous cyclic contractions of capillary walls which often stopped the flow of blood cells, in spleens of rat and mouse. An inverted microscope and oblique lighting were key elements in obtaining images in which the boundaries of cells composing vessel walls were clearly distinguishable. Using slow motion replay, we measured the widths of endothelial cells (C), pericytes (P, when present) and capillary lumens (L; at the site of constriction; U; 15-20 micron upstream), throughout 11-12 min sequences containing many contraction/relaxation cycles. In roughly 50% of contractions L decreased to 0-1 micron, such luminal "closures" occurring within 2-12 sec and lasting for less than 1 sec to greater than 1 min. Intervals between contractions ranged from 12 sec to 3 min (average 1 min). Documentation of one such cycle by sequential photographs from the video monitor is presented, showing dramatic bulging of an endothelial cell into the lumen. Comparison of records of L and C versus time showed that almost invariably when L decreased C increased, and vice versa; highly significant correlations existed between C and L in every case (P less than 0.0005). Multiple linear regression analysis showed that changes in C were responsible for 18-77% of the total variance in L, whereas P contributed only 0-4%; changes in U, covariance between C, P, and U, and unexplained variance were responsible for 0-20, 11-30, and 11-53%, respectively, of the total variance in L. We conclude that these spontaneous capillary contractions were primarily due to endothelial contractility. 相似文献
136.
Zusammenfassung In 23 Sektionsfällen, bei denen am Leichenblut der erythrocytäre Typ Le (a–b–) festgestellt worden war, wurden an paraffineingebetteten Trachealwandproben immunhistochemische Studien durchgeführt. Die Antigendarstellungen erfolgten nach der indirekten Immunperoxidasemethode mit monoklonalen Antikörpern gegen Lea, Leb, A und B als primären Antikörpern; das H-Antigen wurde mit UEA 1 dargestellt. Das Markierungsverhalten der mukösen Drüsen für die ABH-Antigene erlaubte eine eindeutige Differenzierung zwischen Sekretoren und Nonsekretoren. Das Lewis-Markierungsverhalten war in 11 Fällen mit demjenigen Lewis-positiver Individuen identisch. Statistische Betrachtungen legen nahe, daß es sich bei dieser Gruppe tatsächlich um Lewis-positive Individuen handelt, deren erythrocytäre Lewis-Merkmale im gealterten Leichenblut nicht erfaßt wurden. Die übrigen 12 Fälle zeigten ein völlig anderes immunhistochemisches Bild: a) Die Sekretoren (n=9) waren für Lea vollständig negativ; Leb war in einem Falle nicht, in den übrigen Fällen innerhalb muköser Epithelien in minimaler Quantität und atypischer, granulärer Verteilung nachweisbar. b) Nonsekretoren (n=3) wiesen umgekehrt bei völliger Negativität für Leb abortive Markierungen für Lea auf. Diese Beobachtungen, die mit bekannten serologischen Befunden an den Sekreten gut übereinstimmen, sprechen dafür, daß auch in Abwesenheit des Le-Gens in geringer Menge Lewis-Antigene synthetisiert und sezerniert werden können: Möglicherweise kodiert das Allel le eine -4-l-Fucosyltransferase geringer Effizienz. 相似文献
137.
J. Rutenfranz R. Plett P. Knauth R. Condon D. DeVol N. Fletcher S. Eickhoff K. -H. Schmidt R. Donis W. P. Colquhoun 《International archives of occupational and environmental health》1988,60(5):331-339
Summary Sleep length and sleep quality scores were collected on board ships over periods of up to two weeks from 38 watchkeepers working a 4-on/8-off routine and 29 dayworkers. All watchkeepers exhibited fragmented sleeping patterns, which indicated a lack of adaptation of the sleep/wakefulness cycle to the hours of work. There were only slight differences in total sleep length between watchkeepers and dayworkers, however, both groups did not obtain an adequate amount of sleep. Within the watchkeeping crews the 3rd Officers had by far the shortest sleep length. Concerning sleep quality, daytime sleep was generally given the lowest ratings, whereas sleep starting before midnight was on average evaluated as the best, both by watchkeepers and dayworkers. Watchkeeping personnel do not normally have any days off during a voyage so that missed sleep might even amount to a sleep deficit. A solution for this problem could perhaps be a new, stabilized system that allows a single uninterrupted sleep, which is required for full recuperation, to be taken each day.Dedicated to Professor J. Aschoff on the occasion of his 75th birthdayPartly supported by a grant from the Ministry for Technology and Research, Federal Republic of Germany, Project Schiff der Zukunft, Part ET83b 相似文献
138.
Per R. Flood Peter Fritz Schmidt Gro R. Wesenberg Hermod Gadeholt 《Archives of toxicology》1988,62(4):295-300
Two iliac crest needle biopsies were taken from a 43-year-old lead-poisoned woman during and after completion of a Ca-EDTA treatment. By atomic absorption spectroscopy the first and second biopsy were found to contain 56, respectively 41.6 g lead/g wet tissue. In both biopsies 36% of the lead was extractable in 0.1 N HCl. Electron microbeam X-ray analysis proved to have too low sensitivity for quantitation of the lead in these biopsies. Laser microbeam mass analysis (LAMMA), performed only on the second biopsy, revealed a high and fairly constant residual lead concentration in all bone marrow cell nuclei (approximately 55 g/g) and a low lead concentration in the cytoplasm of the same cells (4–12 (g/g). The extracellular bone matrix lead was greatly concentrated in the superficial 3–6 m osteoid zone of the bony trabeculae and totally absent from deeper parts of the mineralized matrix. The LAMMA results are in good agreement with those of subcellular fractionation experiments and atomic absorption spectroscopy, provided that the relative volume fraction of nucleus and cytoplasm is accounted for. The high residual osteoid lead after completed chelation therapy indicates that lead has a stronger affinity for the organic than the mineral components of bone matrix. 相似文献
139.
Models for the development and expression of symptoms in premenstrual syndrome (PMS) must integrate a variety of reported characteristics of the syndrome, such as the symptomatic profile, the menstrual cycle phase-specific timing of the symptoms, treatment response characteristics, and the absence of consistently observed biochemical or psychological markers. In this article, the authors review the available evidence supporting three proposed models for PMS. They also discuss a fourth model that may serve to explain and integrate many of the ostensibly conflicting observations of PMS and direct research toward the further characterization of this syndrome. These models are (1) biochemical or endocrine models; (2) symptom exaggeration or "special sensitivity" models; (3) premenstrual syndrome as a variant of affective disorder; and (4) premenstrual syndrome as a disorder of state regulation. 相似文献
140.
Zusammenfassung Offene Hautdurchtrennungen (Stich-, Schnitt- und Platzwunden) wurden nach Paraffineinbettung zu der Frage untersucht, ob eine vitale Reaktion besteht. Dargestellt wurden Granulozyten mittels Naphthol-AS-D-Chlorazetat Esterase, das Enzym Lysozym sowie insgesamt 8 Proteinasehemmer mit der indirekten Immunperoxidase-Methode. Die untersuchten Gewebeproben wurden dem laufenden Sektionsmaterial entnommen, wobei in 14 Fällen die Lebenszeit eingegrenzt werden konnte (10–165 Min), während in 12 weiteren Fällen der Tod — ohne bekannte Überlebenszeit — akut infolge einer Verletzung großer Gefäße bzw. des Herzens eintrat. Zum Vergleich wurden postmortal gesetzte Verletzungen ebenso hinzugezogen wie Fälle, die durch massive stumpfe Gewalteinwirkung praktisch sofort zu Tode gekommen waren. Es wurde im Rahmen dieser Pilotstudie festgestellt, daß bei vitalen Verletzungen Proteinasehemmer saumartig parallel zur Wundoberfläche angereichert im Corium nachweisbar werden — besonders alpha-2-Makroglobulin und alpha-1-Antichymotrypsin. Proteinasehemmer, die praktisch nur Enzyme der Blutgerinnung bzw. Complementaktivierung neutralisieren (C1-Esterase-Inhibitor und Protein C) zeigten demgegenüber keine oder nur eine geringe Reaktion. In den Vergleichsfällen konnte nur vereinzelt eine Protein-Anreicherung beobachtet werden, jedoch in postmortal gesetzten Wunden in keinem Fall. Eine Abhängigkeit des semiquantitativ erfaßten Farbniederschlages von der Überlebenszeit konnte nicht festgestellt werden. Granulozyten und Lysozym waren nach Überlebenszeiten von mehr als 60 Minuten erstmals im Corium zu beobachten. 相似文献