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1.
应用5-羟色胺特异性抗血清,对眼镜蛇和乌梢蛇消化道含5-HT的内分泌细胞进行了免疫组织化学定位和比较。5-HT细胞的形态在两种蛇中大致相同,消化道各部位都有呈圆形和长梭形(具胞突)的阳性细胞。食道和胃以圆形细胞为主,肠道段则以长梭形细胞为主。眼镜蛇5-HT细胞以十二指肠密度为最高,食道最低;乌梢蛇以幽门部密度为最高,直肠最低。肠道段两者分布特点相同,从十二指肠至直肠分布密度渐疏。本文还对两种蛇5-HT细胞分布型的原因、形态和功能相适应的特点进行了讨论。  相似文献
2.
蛇毒纤维蛋白(原)溶解酶的研究进展   总被引:21,自引:1,他引:20  
符民桂 《蛇志》1996,8(4):33-36
蛇毒纤溶酶能直接溶解纤维蛋白(原),具有作为强力溶栓剂的潜在价值。对蛇毒纤溶酶的深入研究,不仅有助于阐明蛇伤中毒患者的凝血病理机制,而且为其开发应用提供了理论基础。文章综述蛇毒纤溶酶的研究进展及应用前景,重点阐述其分子结构、酶学特性及其与出血活性的关系  相似文献
3.
蕲蛇酶抗栓作用机理的初步分析   总被引:19,自引:6,他引:13  
王晴川  刘广芬 《蛇志》1997,9(3):9-11
动物实验结果示,蕲蛇酶能裂解纤维蛋白原成为可溶性纤维蛋白,降低血中纤维蛋白原浓度,抑制血小板聚集,对抗在酶诱导的血浆凝块订的血浆凝块回缩,因而发挥防血栓形成作用。对纤维蛋白平板试验无直接溶纤作用,但能增加实验动物血中t-PA活性。可能通过促使血管内皮细胞释放t-PA而发挥溶栓作用。  相似文献
4.
We analyzed the origin and evolution of snake venom toxin families represented in both viperid and elapid snakes by means of phylogenetic analysis of the amino acid sequences of the toxins and related nonvenom proteins. Out of eight toxin families analyzed, five provided clear evidence of recruitment into the snake venom proteome before the diversification of the advanced snakes (Kunitz-type protease inhibitors, CRISP toxins, galactose-binding lectins, M12B peptidases, nerve growth factor toxins), and one was equivocal (cystatin toxins). In two others (phospholipase A(2) and natriuretic toxins), the nonmonophyly of venom toxins demonstrates that presence of these proteins in elapids and viperids results from independent recruitment events. The ANP/BNP natriuretic toxins are likely to be basal, whereas the CNP/BPP toxins are Viperidae only. Similarly, the lectins were recruited twice. In contrast to the basal recruitment of the galactose-binding lectins, the C-type lectins were shown to be Viperidae only, with the alpha-chains and beta-chains resulting from an early duplication event. These results provide strong additional evidence that venom evolved once, at the base of the advanced snake radiation, rather than multiple times in different lineages, with these toxins also present in the venoms of the "colubrid" snake families. Moreover, they provide a first insight into the composition of the earliest ophidian venoms and point the way toward a research program that could elucidate the functional context of the evolution of the snake venom proteome.  相似文献
5.
蕲蛇酶对动物实验性血栓的防栓和溶栓作用   总被引:13,自引:1,他引:12  
刘广芬  王晴川 《蛇志》1997,9(3):2-5
采用大鼠颈动脉-颈外静脉回路循环形成的血小板性动脉血栓,用兔脑粉浸出液诱导的大鼠下腔静脉血栓以及用凝血酶诱导的兔耳缘静脉血栓,作为实验性动脉及静脉血栓模型,并分别用阿斯匹林和尿激酶作为阳性对照药,以观察蕲蛇酶对血栓形成的影响。不同剂量的蕲蛇酶(600,300和150μg/kgiv)能使大鼠动脉和静脉血栓形成减少,并呈量效关系。蕲蛇酶对家兔耳缘静脉血栓形成亦表现抑制作用并促进血栓消褪。300和600μg/kg对家兔已形成的动脉和静脉血栓,能促使消褪,提示蕲蛇酶亦有溶栓作用  相似文献
6.
Summary The amino acid sequences of 40 secreted phospholipase A2's (PLA2) were aligned and a phylogenetic tree derived that has three main branches corresponding to elapid (group I), viperid (group II), and insect venom types of PLA2. The human pancreatic and recently determined nonpancreatic sequences in the comparison align with the elapid and viperid categories, repectively, indicating that at least two PLA2 genes existed in the vertebrate line before the divergence of reptiles and mammals about 200–300 million years ago. This allows resolution for the first time of major genetic events in the evolution of current PLA2's and the relationship of human PLA2's to those of snake venom, many of which are potent toxins. Implications for possible mechanisms of regulation of mammalian intra- and extracellular PLA2's are discussed, as well as issues relating to the search for the controlling enzymes in arachidonic acid release, prostaglandin generation, and signal transduction.  相似文献
7.
毒蛇咬伤的早期预测与程序化救治的疗效观察   总被引:11,自引:4,他引:7  
目的通过对毒蛇咬伤的早期预测和处理,评价程序化综合救治方法对毒蛇咬伤的疗效。方法对136例毒蛇咬伤患者除进行“毒蛇咬伤的临床病情分型”外,尽早进行病情预测、血生化(肝、肾功能、凝血功能、心肌酶)检查,同时进行伤口和全身程序化综合救治。观察病情变化,伤口愈合情况及平均住院时间。结果总有效率100%,无过敏反应发生,伤口渗血、肿胀明显缓解,平均住院时间较前缩短。结论早期准确预测和尽快应用程序化救治方法能提高对毒蛇咬伤的疗效。  相似文献
8.
蛇毒类凝血酶的分子生物学研究进展及其应用   总被引:11,自引:1,他引:10  
蛇毒类凝血酶在体外可以作用于纤维蛋白原使其凝固,具有类似凝血酶的功能。但在体内却表现出抗凝、降纤的功能。本概述了蛇毒类凝血酶对纤维蛋白原的识别和作用、序列同源性特点、cDNA克隆的表达以及在临床中的应用。  相似文献
9.
蛇毒抗肿瘤组分的研究进展   总被引:10,自引:0,他引:10       下载免费PDF全文
章良  吴梧桐 《动物学杂志》2003,38(6):120-124
介绍了近几年来蛇毒在抗肿瘤作用方面的最新研究进展。蛇毒抗肿瘤的机制主要有三种:细胞毒作用、阻断整合素及诱导细胞凋亡。本文概述了近年来从不同种蛇毒中分离获得的具有抗肿瘤活性的组分。  相似文献
10.
1. Many organisms rely upon stored energy reserves to support reproduction and do not initiate breeding until their reserves exceed some 'reproductive threshold'. However, the determinants of such thresholds are poorly understood; for example, we do not know if they are fixed (invariant) or respond dynamically to fluctuations in resource availability.
2. An 8-year field study on water pythons ( Liasis fuscus Peters 1873) in tropical Australia shows that individual female pythons adjust their reproductive thresholds in response to annual variation in prey abundance.
3. In every year of the study, female pythons that reproduced were in better condition (mass relative to body length) than non-reproductive females. However, in years with low abundance of rats, female pythons reproduced despite being in relatively poor condition. Indeed, the mean condition of reproductive pythons in one particularly 'bad' year was as low as the mean condition of non-reproductive females in a 'good' year.
4. Clutch sizes were slightly reduced in a 'bad' year, but the main effect of the lowered threshold was greater emaciation of the females after laying.
5. Recapture records of marked snakes show that the annual variation in thresholds is due to flexibility of individual females, not to differential representation of cohorts with different reproductive thresholds.
6. The dynamic adjustment of threshold levels fits well with predictions from life-history models and is likely to be a widespread phenomenon.  相似文献
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