全文获取类型
收费全文 | 1040篇 |
免费 | 32篇 |
国内免费 | 43篇 |
专业分类
1115篇 |
出版年
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 33篇 |
2013年 | 25篇 |
2012年 | 25篇 |
2011年 | 30篇 |
2010年 | 20篇 |
2009年 | 36篇 |
2008年 | 43篇 |
2007年 | 47篇 |
2006年 | 20篇 |
2005年 | 33篇 |
2004年 | 22篇 |
2003年 | 25篇 |
2002年 | 32篇 |
2001年 | 25篇 |
2000年 | 13篇 |
1999年 | 28篇 |
1998年 | 22篇 |
1997年 | 25篇 |
1996年 | 41篇 |
1995年 | 33篇 |
1994年 | 42篇 |
1993年 | 30篇 |
1992年 | 31篇 |
1991年 | 36篇 |
1990年 | 32篇 |
1989年 | 37篇 |
1988年 | 45篇 |
1987年 | 21篇 |
1986年 | 29篇 |
1985年 | 37篇 |
1984年 | 23篇 |
1983年 | 25篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有1115条查询结果,搜索用时 15 毫秒
61.
本文报告刚刺颚口线虫Gnathostoma hispidum和棘颚口线虫Gnathostoma spinigerum流行学和动物实验。证明我国有40种动物充当它们的第一、二中间宿主和转续宿主,其中30种是这两种病源共同宿主。首次报告猕猴Macaca mulatta可作刚刺颚口线虫的第二中间宿主和转续宿主。用刚刺颚口线虫晚第三期幼虫经皮肤感染家猫和小白鼠均得阳性。调查和实验结果表明刚刺颚口线虫和棘颚口线虫的生物学和流行学特性十分相似,显示它们都是人兽共患的寄生虫。文中讨论刚刺颚口线虫的传播途径和人体感染问题。 相似文献
62.
Permanent maxillary canine teeth (C1) are appreciably larger in males than in females in most nonhominid Anthropoidea. Mandibular canines (C1) and mandibular first premolars (P3), against which C1 are sharpened in honing behavior, reflect commensurate sexual dimorphism. These three teeth constitute the canine dental complex. The canine complex crown metrics of seven mature genetically female rhesus Macaques, androgenized by prenatal exposure to testosterone propionate, were compared with a control sample (N = 12) for evidence of masculinization. The C1 and C1 were measured for clinical crown lengths (L) and mesiodistal and buccolingual widths. The functionally significant and highly dimorphic honing dimensions (HD), which approximate the honing surfaces of P3, were noted. In t-test comparisons, the C1 L and P3 HD in androgenized monkeys were significantly larger than those of the control group (P less than 0.05). Identical results were obtained with White's nonparametric ranking technique. Standardized lateral skull radiographs showing earlier dental formative stages were available for five of the seven animals, and these were compared with radiographs of control skulls. The developing C1 were longer and wider than in the controls. This was not reflected in the crown metrics of mature animals because of marked dental attrition. We concluded that androgens can masculinize the female rhesus canine complex, if given during critical periods of prenatal development. We hypothesize that genes encoding the male canine complex are normally activated by endogenous fetal androgens during such critical periods. 相似文献
63.
Intr-individual correlations for cranial, mandibular and dental measurements made on lateral skull radiographs of Macaca nemestrina were systematically higher in 30 adult females than in 31 adult males by an average of 0.11 to 0.15, depending upon method of computation. Clearly, for the adult pig-tailed monkey as in Homo during both prenatal and postnatal life, developmental and dimensional communalities are systematically higher in the female indicating a general principle or trend. 相似文献
64.
65.
人工繁殖恒河猴的血清前清蛋白、转铁蛋白、苹果酸脱氢酶和醇脱氢酶遗传多态性研究 总被引:1,自引:0,他引:1
用薄层聚丙烯酰胺凝胶电泳方法分析118头人繁殖恒河猴血清四种蛋白质和同工酶遗传基因位点的多态性,结果表明,除醇脱氢酶(ADH)为单态外,其余三个基因位点均表现多态,前清蛋白(PA)可分为AA、AB、AC、AD和BB、CC,EE七种表型,各基因的频率为A 0.85,B 0.072,C 0.042,D 0.009,E 0.034转铁蛋白(Tf)可分为CC、DD、EE、FFGG、CD、CE、CG、CH、DE、DF、DG、DH、EF、EG、EH、FG十七种表型,墓因频率为C 0.064,D 0.380,E 0.188,F 0.111,G 0.244,H 0.014,苹果酸脱氢酶(MDH)可分MDH)1-1和MDH2-1两种表型,基因频率为MDH~10.958和MDH~20.042。 相似文献
66.
恒河猴慢性青光眼模型的建立及相关生物学特性 总被引:2,自引:0,他引:2
目的建立两种激光光凝的恒河猴慢性高眼压性青光眼模型,评价模型眼的相关生物学特性。方法成年恒河猴15只,分别采用半导体倍频532激光和氩激光,在房角镜下对功能小梁网区行360°光凝。对其中7只恒河猴分别采用A超、视网膜断层成像仪和视网膜血流仪进行模型眼和另侧对照眼的眼球及视盘形态、血流参数的检测。结果两种光凝模式相比,眼压升高后第4周,倍频532激光组平均眼压为48.4±10.3mmHg,氩激光组平均眼压为44.2±7.0mmHg,倍频532激光组与氩激光组的三次光凝成功率的差异无显著性意义。除视盘面积外,恒河猴模型眼的视杯形态指数、杯盘面积比、盘沿面积、视网膜神经纤维层的平均厚度,与对照眼相比差异有极显著性意义。眼轴和前房深度与对照眼相比差异有显著性意义。筛板血流量、血流速度和红细胞移动速率与对照眼相比差异无显著性意义。结论两种激光光凝恒河猴小梁网均可用以建立慢性高眼压性青光眼模型,模型眼出现青光眼眼底特征性的形态学改变。 相似文献
67.
广西龙虎山猕猴种群生态特征 总被引:4,自引:1,他引:4
1988~1995年,采用定点观察法和绝对计数与相对计数结合法对龙虎山猕猴种群生态作了调查研究。1990年核心区有猕猴14群,500只左右,猴群密度1.6群/km2,种群密度55.6只/km2.猴群大小平均33.8±23.1(n=6)只。一般每隔4~5年分群一次,猴群群体年均增长率14.8%,种群年均增长率为9.7%。猴群中成年猴性比为7.6±6.5(n=12),1~3岁组的性比为0.74±0.61(n=4),群内未成年猴比例为67.7±3.1%(n=12)。发情交配期最早11月12日,最晚次年1月20日,高峰期12月上旬,持续3个月.产仔期最早4月1日,最晚8月14日,高峰期5月上旬,持续时间4个半月.繁殖率45.5%~100%,平均75.4±13.2%(n=21)。新生猴死亡率较低,新生猴性比(雌:雄)平均0.74±0.34(n=5)。 相似文献
68.
广东内伶仃岛猕猴食性及食源植物分析 总被引:8,自引:0,他引:8
论文对内伶仃岛猕猴(Macaca mulatta)的植物食性进行了全面调查,并测定了食源植物适食部分的比重。研究结果表明:(1)猕猴食源植物约200种,以叶食性、果食性最为丰富;(2)猕猴的活动区域以阔叶林、灌木林等植被类型为主;(3)食源植物以热带亚热带成分为主,与栖息地植被组成特征相适应;(4)内伶仃岛猕猴种群发展的容纳量最适为820~1640只(平均1230只),而以743~1485只(平均1114只)最为合适,其总食量约相当于适食性优质植物资源总蕴藏量的10%~20%。 相似文献
69.
Yuzuru Hamada Bambang Suryobroto Shunji Goto Suchinda Malaivijitnond 《International journal of primatology》2008,29(5):1271-1294
Long-tailed macaques (Macaca fascicularis fascicularis) are widely distributed in Southeast Asia and are morphologically and genetically (Tosi et al. in International Journal of Primatology 23:161–178, 2002) distinguishable on either side of the Isthmus of Kra (ca. 10.5°N). We compared the somatometry and body color of 15 local populations of long-tailed macaques in Thailand distributed
over areas from 6.5°N to 16.3°N and also a Thai rhesus macaque population at 17.2°N. Limb proportions and body color variation
follow the geographical trend. However, contrary to a previous report, body size does not decrease with latitude in the northern
group and also in the southern (southerly distributed) rhesus macaque. Relative tail length (RTL) and color contrast in yellow
between the back and thigh are the sole traits that distinctively separate the 2 groups: the southern group has a long relative
tail length (RTL >125%) and small color contrast, whereas the northern group has a short RTL (<120%) and large color contrast.
The southern rhesus macaques appear to have somatometric and body color traits that follow the geographical trend in long-tailed
macaques, though they maintain their distinctive species-specific traits of shorter RTL (ca. 55%), shorter relative facial length, and a bipartite body color pattern. Researchers assume that the northern group of long-tailed
macaques and the southern rhesus macaques had undergone partial introgression with each other. Montane refugia present during
the glacial period are localities in which introgression occurred in long-tailed macaques. 相似文献
70.
Sarah?E.?TurnerEmail author Lisa?Gould David?A.?Duffus 《International journal of primatology》2005,26(6):1435-1457
We studied the relationship between maternal behavior and infant disability in 12 mother-infant dyads for the first 5 weeks
of infant life in the free-ranging Japanese macaque (Macaca fuscata) group on Awaji Island, Japan, from May to September 2001. Congenital limb malformations are prevalent in this population,
and as such carry implications for behavior and conservation. We did not detect any differences in maternal activity budgets,
mother-infant physical contact, infant holding, and overall nursing and infant transport time between mothers of non-disabled
infants, disabled infants that were able to cling to their mothers, and disabled infants whose limb structure prevented clinging.
Mothers of infants with limb malformations severe enough to prevent normal clinging behavior manually supported their infants
during nursing and locomotion significantly more than other mothers did theirs. Increased support-carrying and support-nursing,
and higher frequencies of holding the infant to one's ventrum, suggest that mothers of extensively malformed infants may be
investing more to facilitate the survival of their offspring and that infant disability appears to be influencing maternal
behaviors in this population. 相似文献