全文获取类型
收费全文 | 18112篇 |
免费 | 1731篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 239篇 |
儿科学 | 534篇 |
妇产科学 | 394篇 |
基础医学 | 2232篇 |
口腔科学 | 348篇 |
临床医学 | 2413篇 |
内科学 | 3483篇 |
皮肤病学 | 203篇 |
神经病学 | 1393篇 |
特种医学 | 714篇 |
外国民族医学 | 3篇 |
外科学 | 2411篇 |
综合类 | 467篇 |
一般理论 | 9篇 |
预防医学 | 1993篇 |
眼科学 | 595篇 |
药学 | 1488篇 |
中国医学 | 13篇 |
肿瘤学 | 934篇 |
出版年
2022年 | 113篇 |
2021年 | 317篇 |
2020年 | 207篇 |
2019年 | 292篇 |
2018年 | 322篇 |
2017年 | 207篇 |
2016年 | 284篇 |
2015年 | 299篇 |
2014年 | 405篇 |
2013年 | 577篇 |
2012年 | 810篇 |
2011年 | 870篇 |
2010年 | 472篇 |
2009年 | 405篇 |
2008年 | 736篇 |
2007年 | 826篇 |
2006年 | 846篇 |
2005年 | 779篇 |
2004年 | 763篇 |
2003年 | 694篇 |
2002年 | 659篇 |
2001年 | 568篇 |
2000年 | 598篇 |
1999年 | 525篇 |
1998年 | 212篇 |
1997年 | 189篇 |
1996年 | 187篇 |
1995年 | 186篇 |
1994年 | 162篇 |
1993年 | 148篇 |
1992年 | 408篇 |
1991年 | 413篇 |
1990年 | 381篇 |
1989年 | 397篇 |
1988年 | 344篇 |
1987年 | 328篇 |
1986年 | 330篇 |
1985年 | 314篇 |
1984年 | 262篇 |
1983年 | 223篇 |
1982年 | 150篇 |
1981年 | 118篇 |
1979年 | 193篇 |
1978年 | 167篇 |
1977年 | 141篇 |
1976年 | 128篇 |
1974年 | 160篇 |
1973年 | 144篇 |
1972年 | 129篇 |
1971年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Use of virologic assays for detection of human immunodeficiency virus in clinical trials: recommendations of the AIDS Clinical Trials Group Virology Committee. 总被引:13,自引:9,他引:4 下载免费PDF全文
S Hammer C Crumpacker R D'Aquila B Jackson J Lathey D Livnat P Reichelderfer 《Journal of clinical microbiology》1993,31(10):2557-2564
92.
93.
D W Jackson D K Pitts R Kushner 《The Journal of the American Osteopathic Association》1990,90(12):1071-1080
An accurate prediction of birth weight during gestation can provide useful information for assessing fetal and newborn health status, enabling the clinician to better predict infant morbidity and mortality. Two previously reported standard methods for birth-weight estimation used data collected in utero to derive formulas by least-squares linear regression. The rationale for the inclusion of particular variables in these equations, however, has not been clearly defined. This study was undertaken to examine the efficacy of some previously used variables as well as some new variables in estimating fetal birth weight. The authors used measurements of femur length, biparietal diameter, and abdominal circumference from 107 fetuses (2500 to 4000 g) as variables to compare the two standard methods of birth-weight estimation. A new formula is presented that is derived from a simple model based on the known relationship between volume and weight. The head is represented as a sphere and the body as a cylinder. This study presents a more systematic approach to formula development in which statistical biases are minimized by examining the underlying distributions of the variables used to predict birth weight. 相似文献
94.
A H Newman J Covington M Oleshansky B W Jackson B A Weissman H Leader P K Chiang 《Biochemical pharmacology》1990,40(6):1357-1364
The development of selective irreversible ligands has proven to be an invaluable technique for the isolation, purification and characterization of many receptor proteins. An isothiocyanato-derivative of the muscarinic antagonist aprophen was synthesized and evaluated as a potential irreversible ligand for muscarinic receptors. This compound (aprophit) displaced [3H]N-methylscopolamine binding from rat cerebral cortex with a Ki of 3.1 x 10(-7) M. The inhibition was concentration-dependent and could not be reversed by extensive washing. Aprophit inhibited the acetylcholine-stimulated release of catecholamines from isolated, perfused guinea pig adrenal glands in a concentration-dependent manner. This inhibition was not reversed by perfusing the tissue with Locke's solution and was not due to a non-selective acylation by the isothiocyanate function. The data suggest that aprophit is selectively acylating muscarinic receptor proteins and thus may be useful in their further characterization. 相似文献
95.
Thirty-four social drinkers who had referred themselves to the Regional Brain Damage Unit for assessment of the effects of drinking alcohol were compared with 42 volunteer control subjects of equivalent age but with low alcohol intake, using two 'learning' tests — the Rey Auditory Verbal Learning Test (RAVLT) and the Austin Button Maze. The Maze Test gave no evidence of disorder, but the two groups were significantly different on the RAVLT. No abnormalities in standard cognitive tests were apparent. These results suggest that a deficit in learning ability may be an early feature of the brain dysfunction associated with excessive alcohol consumption. 相似文献
96.
Salim H. Khalil Mohammed H. Qari John M. Jackson Robert Haywood Pyle Hassan El-Solh Abdallah Al-Nasser 《Leukemia research》1994,18(12):881-883
Geographical variations in the incidence of disease are of considerable theoretical and practical importance. It has been claimed that the distribution of acute lymphoblastic leukemia (ALL) phenotypes in Saudi Arabia is different from that recorded in the Western literature. One hundred and twelve (112) patients under 15 years of age, diagnosed as ALL between January 1992 and May 1994 had immunophenotypes performed on their blast cells. Common ALL (cALL) together with pre-B-ALL, formed 86.5% of the total; B-cell 3%, T-cell 6% and null cell 4.5%. These figures are not significantly different from the Western literature. A previous claim from this institution in 1990, that both null and B-cell ALL were significantly increased compared with elsewhere, is not supported by the present figures. Age and sex distribution, and FAB classification, L1 77%, L2 20% and L3 3%, were also of the same order as described elsewhere and, in particular, there was no increase in the frequency of L3 subtype. 相似文献
97.
J Matthew Conoyer David M Kaylie C Gary Jackson 《Otolaryngology--head and neck surgery》2007,137(5):757-761
OBJECTIVES: To investigate common presentations and expected outcomes in patients with traumatically induced otologic dysfunction. STUDY DESIGN: Retrospective case review of patients who underwent otologic surgery for sequelae of otologic trauma over a 28-year period. Patients were stratified into major and minor trauma cohorts. Major trauma was designated as closed head injury with or without temporal bone fracture; lower-energy insults comprised the minor trauma group. Preoperative and postoperative audiograms were obtained and correlated with extent of injury. SETTING: Tertiary referral center. RESULTS: Major trauma accounted for 44.9 percent of all patients. The remaining 55.1 percent suffered minor trauma, of which simple traumatic tympanic membrane perforation was the most common insult (33.6%). Two hundred twenty-seven cases were performed on 214 patients. Pure tone averages improved a significant 20.8 dB to essentially normal levels postoperatively. CONCLUSION: Regardless of injury extent, surgical rehabilitation of conductive losses attains excellent hearing results that surpass those historically reported for the chronic ear population. 相似文献
98.
99.
D. M. Jackson C. E. Wallsten E. Jerning P.-S. Hu A. M. Deveney 《Psychopharmacology》1998,139(4):300-310
The aim was to study firstly, the motor effects of a new 5-HT1A antagonist, NDL-249 [(R)-3-(N-cyclopentyl-N-propylamino)-8-fluoro-3,4-dihydro-2H-1-benzopyran-5-carboxamide hydrochloride] and of the reference 5-HT1A antagonist WAY-100 635 [N-(2-(1-(4-(2-methoxyphenyl)piperazinyl))ethyl)-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride], in comparison to the 5-HT1A agonist (±)-8-OH-DPAT [(8-hydroxy-2-(di-N-propylamino) tetralin, hereafter 8-OH-DPAT], in rats acclimatised to the automated activity cages; secondly, to study whether
the behavioural effects of NDL-249 and 8-OH-DPAT are sensitive to the 5-HT depleting effects of p-chlorophenylalanine (PCPA); thirdly, to characterise the nature of the antagonist-induced activation seen in the automatic
activity cages with the aid of a behavioural observation analysis; fourthly, to examine the interaction between the 5-HT1Areceptors mediating the behavioural effects and dopamine (DA) receptors. NDL-249 was found to bind in vitro to rat hippocampal
5-HT1A receptors with high affinity and selectivity. In second messenger studies, it was devoid of agonist-like effects. In the
locomotor activity studies, each antagonist significantly increased the incidence of horizontal activity, peripheral activity
and rearing. 8-OH-DPAT, while significantly increasing peripheral and horizontal activities, decreased the incidence of rearing.
PCPA blocked the motor effects of NDL-249 but did not affect those of 8-OH-DPAT. Observational analyses indicated that NDL-249
induced significant increases at one or more doses in sniffing, rearing and locomotion together with a significant reduction
in stillness. WAY-100 635 significantly increased the incidence of rearing, intense grooming and vacuous chewing. The significant
increases in sniffing, grooming and intense grooming and the significant decrease in stillness induced by the DA D1 agonist, SK&F 38393 [(±)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochloride], were not altered by concomitant
pre-treatment with NDL-249. Pre-treatment of rats with either the DA D1 antagonist SCH-23390 (2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol) or the DA D2 antagonist, raclopride, blocked the reduced stillness and increased sniffing and rearing induced by NDL-249. In conclusion,
5-HT1A antagonists including the new selective antagonist, NDL-249, induce mild behavioural activation in rats, which is mediated
probably indirectly via DA systems.
Received: 3 April 1997/Final version: 23 February 1998 相似文献
100.
Alison Bushell Leslie Klenerman Helen Davies Ian Grierson Malcolm J. Jackson 《Acta orthopaedica》1996,67(4):393-398
We examined the potential protective effect of pretreatment with corticosteroids or antioxidants (ascorbic acid or allopurinol) in rabbits with reper-fusion-induced damage to skeletal muscle after ischemia.
4 hours of limb ischemia induced by a pneumatic tourniquet, followed by reperfusion for 1 hour, caused a considerable amount of ultrastructural damage to the anterior tibialis muscles accompanied by a rise in circulating creatine kinase activity. Pretreatment of animals with depomedrone by a single 8 mg bolus injection led to a preservation of the anterior tibialis structure on both light and electron microscopy. High-dose continuous intravenous infusion with ascorbic acid (80 mg/hr) throughout the period of ischemia and reperfusion also preserved skeletal muscle structure, although allopurinol in various doses had no protective effect.
These data are fully compatible with a mechanism of ischemia/reperfusion-induced injury to skeletal muscle, involving generation of oxygen radicals and neutrophil sequestration and activation. They also indicate that damage to human skeletal muscle caused by prolonged use of a tourniquet is likely to be reduced by simple pharmacological interventions. 相似文献
4 hours of limb ischemia induced by a pneumatic tourniquet, followed by reperfusion for 1 hour, caused a considerable amount of ultrastructural damage to the anterior tibialis muscles accompanied by a rise in circulating creatine kinase activity. Pretreatment of animals with depomedrone by a single 8 mg bolus injection led to a preservation of the anterior tibialis structure on both light and electron microscopy. High-dose continuous intravenous infusion with ascorbic acid (80 mg/hr) throughout the period of ischemia and reperfusion also preserved skeletal muscle structure, although allopurinol in various doses had no protective effect.
These data are fully compatible with a mechanism of ischemia/reperfusion-induced injury to skeletal muscle, involving generation of oxygen radicals and neutrophil sequestration and activation. They also indicate that damage to human skeletal muscle caused by prolonged use of a tourniquet is likely to be reduced by simple pharmacological interventions. 相似文献