全文获取类型
收费全文 | 2220篇 |
免费 | 148篇 |
出版年
2019年 | 23篇 |
2017年 | 29篇 |
2016年 | 29篇 |
2015年 | 53篇 |
2014年 | 49篇 |
2013年 | 69篇 |
2012年 | 82篇 |
2011年 | 61篇 |
2010年 | 64篇 |
2009年 | 48篇 |
2008年 | 77篇 |
2007年 | 92篇 |
2006年 | 56篇 |
2005年 | 71篇 |
2004年 | 56篇 |
2003年 | 33篇 |
2002年 | 50篇 |
2001年 | 53篇 |
2000年 | 46篇 |
1999年 | 52篇 |
1998年 | 24篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 23篇 |
1994年 | 23篇 |
1993年 | 25篇 |
1992年 | 31篇 |
1991年 | 33篇 |
1990年 | 27篇 |
1989年 | 33篇 |
1988年 | 25篇 |
1987年 | 37篇 |
1986年 | 25篇 |
1985年 | 27篇 |
1984年 | 32篇 |
1983年 | 25篇 |
1980年 | 23篇 |
1979年 | 23篇 |
1975年 | 22篇 |
1974年 | 24篇 |
1973年 | 28篇 |
1972年 | 26篇 |
1965年 | 40篇 |
1963年 | 39篇 |
1962年 | 28篇 |
1961年 | 37篇 |
1960年 | 29篇 |
1959年 | 32篇 |
1958年 | 29篇 |
1957年 | 24篇 |
排序方式: 共有2368条查询结果,搜索用时 15 毫秒
31.
SYNOPSIS. Plasmodium balli sp. nov. is described from Anolis lionotus and A. poecilopus of central Panama.
Large, elongate gametocytes and segmenters containing up to 100 merozoites are produced by P. balli. Proerythrocytes and normoblasts are more commonly parasitized than erythrocytes. Pigment is uncommon, but when present consists of a minute dot. Hypertrophy, distortion and lysis of host cell nuclei may result from parasitization of immature blood cells by gametocytes, while enucleated host cells are common. 相似文献
Large, elongate gametocytes and segmenters containing up to 100 merozoites are produced by P. balli. Proerythrocytes and normoblasts are more commonly parasitized than erythrocytes. Pigment is uncommon, but when present consists of a minute dot. Hypertrophy, distortion and lysis of host cell nuclei may result from parasitization of immature blood cells by gametocytes, while enucleated host cells are common. 相似文献
32.
The Control of Color in Mammals 总被引:1,自引:0,他引:1
SYNOPSIS. Recent advances in the biology of mammalian pigmentationare reviewed.Particular attention is given to emerging informationon the integration of pigmentary events occurring at differentlevels of biological organization within mammalian skin andhair. The structural and functional significance of keratinocytesand melanocytes as components of mammalian epidermal melaninunits is viewed from this perspective. New evidence on the natureof genetic, developmental, endocrine, and radiation influenceson performance of melanocytes and the establishment of pigmentarypatterns is summarized. 相似文献
33.
34.
The fixing-staining mixture consisted of 1 part of 2% aqueous OsO4 and 3 parts of 3% Nal in distilled water. Fresh lungs were cut into 2 mm slices and immersed in this solution for 24 hr at room temperature. Controls were fixed in buffered OsO4 alone. Selective staining of type II alveolar cells was shown by the OsOt-NaI mixture but was absent in the controls. No additional staining of the sections was required, and the selectivity was readily observable in either paraffin or Araldite sections by light microscopy and in Araldite sections by electron microscopy 相似文献
35.
SYNOPSIS Plasmodium gonatodi sp. nov. is described from Gonatodes albogularis fuscus of eastern Panama. It is characterized by elongate gametocytes and polymorphic schizonts containing 12-46 nuclei when apparently mature. Both proerythrocytes and erythrocytes are commonly parasitized, host cells are hypertrophied and distorted, and their nuclei are displaced. Prematuration sexual stages may be irregularly shaped and larger than mature gametocytes.
Plasmodium diploglossi Aragão and Neiva , 1909 is reported from Mabuya mabouya in eastern Panama, and Plasmodium morulum sp. nov. is described from this host. P. morulum usually parasitizes immature erythrocytes, and is characterized by lenticular or oval to round gametocytes, and schizonts with 14-40 nuclei usually arranged in a globular mass. Host cells are slightly hypertrophied and distorted, and their nuclei are usually displaced. Inoculation of infected blood into clean hosts produces numerous schizonts in white cells as well as in the erythrocyte series.
Pigment in both P. gonatodi and P. morulum , if present, consists of a few minute dark dots which do not meet the polarized light test for hemozoin. 相似文献
Plasmodium diploglossi Aragão and Neiva , 1909 is reported from Mabuya mabouya in eastern Panama, and Plasmodium morulum sp. nov. is described from this host. P. morulum usually parasitizes immature erythrocytes, and is characterized by lenticular or oval to round gametocytes, and schizonts with 14-40 nuclei usually arranged in a globular mass. Host cells are slightly hypertrophied and distorted, and their nuclei are usually displaced. Inoculation of infected blood into clean hosts produces numerous schizonts in white cells as well as in the erythrocyte series.
Pigment in both P. gonatodi and P. morulum , if present, consists of a few minute dark dots which do not meet the polarized light test for hemozoin. 相似文献
36.
Previous workers have shown that some strains ofAspergillus nidulans produce penicillin-like substances. In the present studies, shake-flask cultures of 101 wild-type strains ofA. nidulans, representatives of 18 different heterokaryon-compatible groups, were examined and filtrates of most found to inhibit the growth of a strain ofBacillus subtilis sensitive to penicillin, although members of two of these groups had no detectable antibiotic activity. Five strains with antibacterial properties were chosen for detailed investigation as well as two genetically labelled derivatives obtained from one of these after ultraviolet light treatments; one derivative had a similar antibiotic yield to its original wild-type parent but the other was selected as having increased antibiotic yield. The antibiotic produced by these seven strains was by all tested criteria, including chromatographic and electrophoretic behaviour, indistinguishable from penicillin. A heterokaryon test between the two mutants indicated that antibiotic productivity was under nuclear control. 相似文献
37.
Further evidence of oxygen diffusion as the determining factor in the relation between disk thickness and respiration of potato tissue 总被引:2,自引:2,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Macdonald IR 《Plant physiology》1968,43(2):274-280
The effect of oxygen tension above atmospheric pO2 on the development of respiratory capacity in potato disks has been examined. Raising the oxygen tension of the aqueous environment to 40% during the aging of 2.0 mm or 3.0 mm thick disks at 25° progressively increased the respiration rate of the tissue as shown by subsequent assay in 100% oxygen. Disks 3.0 mm thick showed a greater response to increased pO2 than did 2.0 mm disks. A comparison of center 1.0 mm sections excised from 3.0 mm disks after aging, showed that the respiration rate of internal tissue from disks aged in high pO2 was approximately 40% greater than such tissue aged with atmospheric pO2. The characteristic inverse relationship between respiration rate and thickness in aged disks can be modified from a concave-downwards curve to a convex-downwards curve by pretreating the tissue with increased pO2, thus indicating that raising the pO2 during aging can increase the thickness threshold at which the transition from tissue manifesting the respiratory characteristics of thin disks to that manifesting the characteristics of thick disks, occurs. Similarly increased pO2 during aging can modify the hyperbolic relationship obtaining between pretreatment temperature in the range 10° to 25° and respiratory capacity of aged 3.0 mm disks, to approximate to the linear relationship observed with 0.75 mm disks. It is concluded that the development of respiratory capacity in disks between 0.75 mm and 3.0 mm thick is restricted by oxygen dificiency and that the characteristic inverse relationship between respiration rate and thickness in aged disks is largely attributable to this factor, the influence of which is discernible both on the development of respiratory capacity and on its subsequent assay. 相似文献
38.
Partitioning of respiratory flow resistance in man 总被引:9,自引:0,他引:9
39.