全文获取类型
收费全文 | 532篇 |
免费 | 39篇 |
专业分类
571篇 |
出版年
2024年 | 3篇 |
2022年 | 15篇 |
2021年 | 17篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 33篇 |
2015年 | 29篇 |
2014年 | 24篇 |
2013年 | 36篇 |
2012年 | 42篇 |
2011年 | 38篇 |
2010年 | 21篇 |
2009年 | 18篇 |
2008年 | 29篇 |
2007年 | 21篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 19篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1962年 | 2篇 |
排序方式: 共有571条查询结果,搜索用时 10 毫秒
561.
562.
563.
564.
565.
Satya Narayan Arya 《Primates; journal of primatology》1981,22(2):261-265
Probstmayria nainitalensis n. sp. is described from the rectum of the rhesus macaque,Macaca mulatta, from Nainital, India. The new form consists of morphologically dissimilar spicules, spicular ratio 1:1.41–1.50, tip of shorter
spicule elongate and blunt, six pairs of postanal papillae and a prominent gubernaculum in the male and didelphic ovaries
and postequatorial vulva in the female.
A key to the species is also furnished. 相似文献
566.
Seven rhodamine-conjugated lectins (PNA, RCA I, SBA, Con A, WGA, UEA I, and DBA; see Table 1) were utilized in studying the staining pattern of glycoproteins in rat testis and epididymis after ligation of ductuli efferentes (DE), corpus epididymidis (CE), and vas deferens (VD) for various time periods. Ductuli efferentes ligation caused a widening of seminferous tubules and detachment of spermatids with formation of multinuclear cells. These cells acquired a strong affinity for all lectins. Corpus epididymidis ligation also caused degeneration of spermatids with increased lectin staining in some tubules, but after 7 days another cell population close to the periphery of seminiferous tubules showed an increased nuclear affinity for some lectins followed by a clear degeneration and strong cytoplasmic staining with all lectins. Vas deferens ligation caused no degenerative changes in testicular spermatids. However, the peripheral cell population showed degenerative changes similar to those found after CE ligation. In both cases this was coincident with the formation of spermatic granulomas at the site of ligation. Ductuli efferentes ligation caused a gradual decrease of intratubular content in caput epididymidis, while the contrary was true after CE ligation. The latter was associated with intratubular accumulation of lectin-positive swollen cells and sperm aggregates as well as an increased lectin staining of narrow cells in initial segment and light cells in distal caput. After VD ligation an increased staining of light cells was initially found in distal cauda and distal caput, but, concomitant with distension of the tubules this reaction decreased.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
567.
Rhizobium sp. 127E15 fixed nitrogen asymbiotically, when grown in induction media. Highest level of acetylene reduction activity was reached in LNB5 medium and in media containing a combination of two sugars, sucrose and arabinose. In the induced cultures, large pleomorphic forms of bacteroids were produced. Considerable acetylene reduction activity was recorded in the rhizosphere of the lima bean plants that were inoculated with rhizobia and grown in pot cultures. Trace amounts of activity could also be detected in the rhizobia adhering to the rhizoplane. 相似文献
568.
Fungal organisms cause diseases in plants, animals, and human beings. They are responsible for deterioration of organic objects.
Scientists have found that it is not the occurrence but quantum of inoculum or number of spores per unit area which has a
direct effect on development of diseases in fields as well as in markets. An aerobiological survey of three fruit markets
of Vadodara, India was undertaken during 2006 to determine various fungal pathogens present in the atmosphere using the petriplate
exposure method. Isolations were also done from six fruits available during summer and rainy seasons. The surface washing
technique yielded 12 micro fungi from Prunus avium. Direct correlation was observed between percentage rot of fruits and occurrence of fungal spores in different months. 相似文献
569.
S N Arya 《Boletín chileno de parasitología》1992,47(1-2):38-39
Kathlania sprentii n. sp. is described from the intestine of a marine fish. Trichiurus muticus (Griffith) from the South coast of Indian Ocean, India. The new form differs from other known species of the genus in the presence of two rounded teeth-like structures in the buccal capsule, spicule ratio 1:4 and rod-shaped gubernaculum with bifurcated distal end. 相似文献
570.
Human immunodeficiency virus type-2 gene expression: two enhancers and their activation by T-cell activators 总被引:5,自引:0,他引:5
S K Arya 《The New biologist》1990,2(1):57-65
The human immunodeficiency viruses (HIVs) may include a spectrum of retroviruses with varying potential to infect their host, undergo long periods of latent infection, and induce pathology. Since expression of the viruses is in large part regulated by the sequence elements in their long terminal repeats (LTRs), this study was directed to an analysis of the regulatory elements in the HIV-2 LTR. The HIV-2 LTR was found to contain two enhancers. One of these enhancers is, in part, identical to the HIV-1 enhancer. This enhancer in HIV-1 is the T-cell activation response element; in HIV-2, however, it is the second enhancer that is mainly responsible for activation in response to T-cell activators. The second enhancer interacts with two nuclear binding proteins (85 kD and 27 kD mobility) that appear to be required for optimal enhancer function and activation. Observations such as these encourage the speculation that there may be subtle differences in the regulation of HIV-1 and HIV-2 expression that may be relevant to the possible longer latency and reduced pathogenicity of HIV-2. 相似文献