全文获取类型
收费全文 | 391篇 |
免费 | 34篇 |
国内免费 | 29篇 |
专业分类
儿科学 | 14篇 |
妇产科学 | 6篇 |
基础医学 | 39篇 |
口腔科学 | 26篇 |
临床医学 | 45篇 |
内科学 | 84篇 |
皮肤病学 | 8篇 |
神经病学 | 20篇 |
特种医学 | 113篇 |
外科学 | 11篇 |
综合类 | 23篇 |
预防医学 | 23篇 |
眼科学 | 3篇 |
药学 | 27篇 |
肿瘤学 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 16篇 |
2004年 | 8篇 |
2003年 | 14篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 21篇 |
1997年 | 26篇 |
1996年 | 21篇 |
1995年 | 8篇 |
1994年 | 25篇 |
1993年 | 23篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 5篇 |
排序方式: 共有454条查询结果,搜索用时 390 毫秒
1.
以18-甲基-17β-羟基-17α-乙炔基-雌甾-4-烯-3-酮(18-甲基炔诺酮),17β-羟基-17α-乙缺基-雌甾-4-烯-3-酮(炔诺酮),17β-羟基-17α-乙炔基-雄甾-4-烯-3-酮(妊娠素)和17a-羟基孕甾-4-烯-3,20二酮(17α-羟基黄体酮)为原料,经NaBH,还原、脱水、双键转位和酯化等反应合成一系列3,5-甾二烯化合物,用1HNMR和MS证明了它们的结构。动物筛选结果表明,17β-丙酰氧基-17α-乙炔基-雌甾-3,5-二烯(IVb2有明显的抗早孕活性。中断早期妊娠的作用似与其雌激素活性有关。 相似文献
2.
3.
4.
GD Cramer DJ Allen LJA DiDio W Potvin R Brinker 《Surgical and radiologic anatomy : SRA》1990,12(4):287-290
Summary Accurate volume determination of the encephalic ventricles is of importance in several clinical conditions, including Alzheimer's presenile dementia, schizophrenia, and benign intracranial hypertension. Previous studies have investigated the accuracy with which magnetic resonance imaging (MRI) can be used in clinical practice to evaluate the encephalic ventricles. However, adequate evaluation of pathological conditions depends on a sufficient amount of morphometric data from normal subjects. To begin establishing this data base for normal subjects, we evaluated the MRI scans of 38 subjects found to have no apparent pathology and calculated the ventricular volume in each case by using methods previously developed in our laboratory. The results were then compared with published volumes determined from studies that used either ventricular casts or computerized tomographic scans. The average total ventricular volume for all 38 subjects was 17.4 cm3, while that for males was 16.3 cm3 and that for females was 18.0 cm3. A small but significant correlation was found between age of subject and ventricular volume, with ventricular size increasing with age.
Evaluation du volume des ventricules cérébraux à partir des images obtenues en résonance magnétique nucléaire chez 38 sujets humains
Résumé La détermination exacte du volume des ventricules cérébraux est importante en clinique comme par exemple dans la démence présénile d'Alzheimer, la schizophrénie et l'hypertension intracrânienne bénigne. Des études antérieures ont étudié la fiabilité de la résonance magnétique nucléaire en pratique clinique pour évaluer le volume des ventricules cérébraux. Toutefois une évaluation correcte dans les conditions pathologiques implique une bonne connaissance des données morphométriques du sujet normal. Pour établir ces données sur « le sujet normal », nous avons étudié les coupes obtenues en IRM chez 38 sujets apparemment indemnes de toute pathologie; nous avons calculé le volume ventriculaire dans chaque cas en utilisant des méthodes mises au point auparavant dans notre laboratoire. Les résultats ont été ensuite comparés avec ceux obtenus par d'autres études utilisant soit des moules ventriculaires, soit des coupes tomographiques computérisées. Le volume ventriculaire total moyen chez 38 sujets est de 17,4 cm3, mais il est chez les sujets masculins de 16,3 cm3 et chez les sujets de sexe féminin de 18 cm3. Une corrélation faible mais significative a été trouvée entre l'âge du sujet et le volume ventriculaire, étant entendu que la taille du ventricule augmente avec l'âge.相似文献
5.
6.
It has been reported that bovine colostrum (BC) supplementation improves buffer capacity () during exercise, but whether the improvement results from changes in tissue and/or blood buffer systems has not been determined. The purpose of the present study was to examine the effect of supplementation with BC on blood buffer systems. Thirteen elite females rowers were supplemented with 60 g·day–1 of either BC (n=6) or whey protein (WP, n=7) during 9 weeks of pre-competition training in a randomised, double-blind, placebo-controlled, parallel design. All subjects undertook the study as a group and completed the same training program. Resting haemoglobin (Hb) concentration and plasma buffer capacity (p) (determined by titration with HCl) were measured pre- and post-supplementation. There were no differences in macronutrient intakes (P>0.56) or training volumes (P>0.99) between BC and WP during the study period. There were no differences in Hb [BC 13.28 (0.28) mg·dl–1, WP 13.70 (0.26) mg·dl–1; P=0.45] or p [BC 14.8 (1.1) nmol HCl·ml–1·pH–1, WP 14.8 (0.5) nmol HCl·ml–1·pH–1; P=0.68] between groups at week 0. p increased in both groups during the study period (P<0.001), but the increases were not significantly different between groups (P=0.52). Hb did not change significantly in either group (P=0.35). These data indicate that supplementation with BC does not affect p or Hb. We therefore suggest that adaptations in tissue buffer systems are responsible for the previously reported increases in buffer capacity that result from BC supplementation. 相似文献
7.
D Anderson M H Brinkworth P C Jenkinson S A Clode D M Creasy S D Gangolli 《Teratogenesis, carcinogenesis, and mutagenesis》1987,7(2):141-158
Adult male CD rats and CD-1 mice were given a single oral dose of ethylene glycol monomethyl ether (EGM) at 0, 500, 750, 1,000, or 1500 mg/kg. Groups of 10 were killed at weekly intervals after dosing for analysis of sperm counts and morphology or testicular histology; further groups of 10 were sequentially mated to pairs of virgin females to test for dominant lethality or gross foetal malformations in the F1 generation (F1 abnormalities). EGM was found to deplete the spermatocytes of both species severely, principally pachytene cells, but with other stages affected with increasing dose. A delay in the progression of spermatogenesis may account for a discrepancy between the apparent stage-specificity of damage deduced from lowered sperm counts and that observed histologically. In the rat, morphological abnormalities were observed in sperm that had been exposed as spermatocytes; in the mouse, however, the sensitive cells were the late spermatocytes and early spermatids. In all these parameters there was an indication of a dose-response relationship in both rats and mice. In the mating studies EGM induced a dose-related decrease in fertility 5 weeks after dosing in the rat, but complete sterility in all but the lowest dose after 6 weeks. In contrast, EGM had no effect on the reproductive capacity of the mouse. There was no statistically significant evidence for the induction of dominant lethal mutations or F1 abnormalities in either species. A single oral dose of cyclophosphamide (CTX) at 100 mg/kg induced a significant increase in dominant lethality in both species. CTX reduced the number of total implants in the rat and induced a nonsignificant increase in the number of abnormal offspring sired by treated male mice. 相似文献
8.
Schmid TE Brinkworth MH Hill F Sloter E Kamischke A Marchetti F Nieschlag E Wyrobek AJ 《Human reproduction (Oxford, England)》2004,19(6):1395-1400
BACKGROUND: Modern reproductive technologies are enabling the treatment of infertile men with severe disturbances of spermatogenesis. The possibility of elevated frequencies of genetically and chromosomally defective sperm has become an issue of concern with the increased usage of ICSI, which can enable men with severely impaired sperm production to father children. Several papers have been published reporting aneuploidy in oligozoospermic patients, but relatively little is known about chromosome structural aberrations in the sperm of these patients. METHODS: We examined sperm from infertile, oligozoospermic individuals for structural and numerical chromosomal abnormalities using a multicolour ACM fluorescence in situ hybridization (FISH) assay that utilizes DNA probes specific for three regions of chromosome 1 to detect human sperm that carry numerical chromosomal abnormalities plus two categories of structural aberrations: duplications and deletions of 1pter and 1cen, and chromosomal breaks within the 1cen-1q12 region. RESULTS: There was a significant increase in the average frequencies of sperm with duplications and deletions in the infertility patients compared with the healthy concurrent controls. There was also a significantly elevated level of breaks within the 1cen-1q12 region. There was no evidence for an increase in chromosome 1 disomy, or in diploidy. CONCLUSIONS: Our data reveal that oligozoospermia is associated with chromosomal structural abnormalities, suggesting that oligozoospermic men carry a higher burden of transmissible, chromosome damage. The findings raise the possibility of elevated levels of transmissible chromosomal defects following ICSI treatment. 相似文献
9.
Congenital pulmonary atresia with ventricular septal defect: angiographic and surgical correlates 总被引:1,自引:0,他引:1
Of 181 patients with severe congenital pulmonary atresia and ventricular septal defect or "type IV truncus" (an obsolete term), all but 11% had true central pulmonary arteries. These arteries were demonstrable by large serial biplane angiograms using multiple selective injections into collateral vessels, frequent photographic subtraction, and occasional pulmonary vein-wedge angiograms. These techniques are extremely important for accurate diagnosis and in planning corrective or palliative surgery, which was done in 77% of patients with pulmonary arteries. 相似文献
10.
GD单抗治疗神经母细胞瘤临床应用协作组 《临床儿科杂志》2022,40(1):14-20
神经母细胞瘤(neuroblastoma,NB)是儿童最常见的颅外实体肿瘤,临床表现及预后具有高度异质性。低危患儿预后较好,高危患儿即使接受化疗、放疗、手术、造血干细胞移植等多种方法的综合治疗,长期存活率仍不足50%。探索潜在的治疗靶点对于提高高危患者的生存率具有重要意义。双唾液酸神经节苷脂抗原GD2在NB细胞高表达,达妥昔单抗β可与NB细胞膜表面过表达的GD2特定靶点结合,触发抗体依赖性细胞介导的细胞毒性作用和补体依赖的细胞毒性效应,通过双重免疫机制而发挥抗肿瘤作用。通过总结国外多项关键临床研究,并结合在海南和天津医疗先行区的上市前初步应用经验,我们对达妥昔单抗β的安全性、有效性、适用人群及使用方法进行总结和推荐,提出本共识,旨在为临床医师提供指导与帮助。 相似文献