全文获取类型
收费全文 | 1828篇 |
免费 | 276篇 |
国内免费 | 1篇 |
出版年
2021年 | 23篇 |
2020年 | 27篇 |
2019年 | 50篇 |
2018年 | 51篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 44篇 |
2014年 | 38篇 |
2013年 | 74篇 |
2012年 | 62篇 |
2011年 | 64篇 |
2010年 | 61篇 |
2009年 | 47篇 |
2008年 | 76篇 |
2007年 | 67篇 |
2006年 | 59篇 |
2005年 | 65篇 |
2004年 | 58篇 |
2003年 | 63篇 |
2002年 | 56篇 |
2001年 | 60篇 |
2000年 | 62篇 |
1999年 | 45篇 |
1998年 | 32篇 |
1997年 | 25篇 |
1996年 | 41篇 |
1995年 | 39篇 |
1994年 | 21篇 |
1993年 | 32篇 |
1992年 | 41篇 |
1991年 | 63篇 |
1990年 | 40篇 |
1989年 | 41篇 |
1988年 | 32篇 |
1987年 | 35篇 |
1986年 | 26篇 |
1985年 | 21篇 |
1984年 | 26篇 |
1983年 | 23篇 |
1982年 | 17篇 |
1981年 | 22篇 |
1979年 | 26篇 |
1978年 | 21篇 |
1977年 | 17篇 |
1974年 | 17篇 |
1972年 | 18篇 |
1971年 | 16篇 |
1970年 | 20篇 |
1967年 | 20篇 |
1966年 | 16篇 |
排序方式: 共有2105条查询结果,搜索用时 31 毫秒
1.
2.
3.
William J. Robbins 《American journal of botany》1960,47(6):485-491
Robbins , William J. (The New York Botanical Garden, New York, N. Y.) Further observations on juvenile and adult Hedera. Amer. Jour. Bot. 47(6) : 485–491. Illus. 1960.—Plants of arborescent Hedera helix sprayed with gibberellic acid produced juvenile shoots. Juvenile characters appeared in December to March from applications of gibberellic acid made from May to July. Gibberellic acid modified inflorescences toward a vegetative condition. Previous reports that seeds of arborescent Hedera helix produce juvenile plants were confirmed. Seedlings of a variant, Hedera helix ‘238th Street,‘ which has adult-shaped leaves on a vine type of growth produced vines with lobed leaves. Heavy pruning of arborescent Hedera helix caused the production of juvenile shoots. 相似文献
4.
5.
A case of chromomycosis in which hyperthermia proved effective is reported. The patient was a 56-year-old male bean curd maker who, without any previous history of minor trauma, developed on the extensor side of the left upper arm an eczematous lesion that underwent gradual radial expansion. The lesion showed a well-defined, 7×10 cm infiltrated erythematous plaque with the central area healed and, at the upper and lower borders, adherent scales and crusts on the surface. Histological examination revealed granulomatous changes in the dermis, as well as sclerotic cells within giant cells and microabscesses. On culturing,Fonsecaea pedrosoi was isolated. The patient was treated with disposable chemical pocket warmers, which were secured over the lesion with a rather tight elastic bandage, so that they kept the affected area warm for 24 hours a day. After a month of such hyperthermic treatment, the erythema and infiltration had decreased considerably, and microscopic examination and culture of the crusts both yielded negative results. Examination of biopsy specimens of the lesion after the third month showed that it had cicatrized. The treatment was stopped after 4 months, and no relapse occurred. We also summarize the published results of local hyperthermic treatment of chromomycosis in Japan. 相似文献
6.
7.
8.
9.
Lipoproteins, especially HDL, are carriers of a small fraction of the thyroid hormones in plasma and participate in the intracellular transport of T4. In previous work we showed that a brief period of hypothyroidism alters the hormone distribution among the lipoproteins, causing a decrease in VLDL and LDL binding despite a relative increase in VLDL and LDL cholesterol, an increase in HDL binding, and a reversal of T4 and T3 binding to the smallest HDL size subgroup. The present study of three patients with thyroid hormone resistance and largely compensated hypothyroidism showed thyroid hormone distribution that differed markedly from both normal and hypothyroid subjects. The most striking difference was a much lower binding of both T4 and T3 to HDL and a much higher binding to LDL. If confirmed in a larger group of patients, this might serve as a marker for thyroid hormone resistance. 相似文献
10.
R. L. Robbins 《Journal of fish biology》2007,70(5):1350-1364
The seasonal temporal sexual segregation of white sharks Carcharodon carcharias , at the Neptune Islands, South Australia, is described in relation to environmental variables. A significant sexual segregation was found at this site with sex ratios strongly favouring males overall. Males were more prevalent than females in all months in a 3 year sampling period, aside from April and May. There was a significant difference between the sexes in terms of mean daily numbers over the months of the study. It was also observed that sexual segregation fluctuated for unknown reasons on a temporal scale. Predictive models for estimating male and female numbers based on a series of abiotic factors were generated. Sea surface temperature, tidal height, tidal range, moon phase, cloud cover, underwater visibility and swell height were related to daily sightings of male and female white sharks to determine the influence of these variables on sexual segregation. Visibility and sea surface temperature affected male numbers, however, visibility did not affect sexual segregation. Tidal height was significantly different between males and females. Sea surface temperature also appeared to be related to sexual segregation in this species. Females were present when temperatures ranged from 15·7 to 18·1° C whereas males were observed at temperatures ranging from 14·3 to 17·8° C, with a peak in sightings in September, when sea surface temperatures were at their lowest. Since parturition is thought to occur in spring or summer, it is suggested that females are absent at this time and only return during prime feeding periods or times at which temperatures are elevated in order to increase developmental growth rates of their young. The significantly lower temperatures in 2003 may explain the absence of females in this year. Hypotheses related to temperature regulation in this species are put forward to explain the sexual segregation observed. 相似文献