全文获取类型
收费全文 | 1224篇 |
免费 | 92篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 15篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 23篇 |
2016年 | 34篇 |
2015年 | 43篇 |
2014年 | 52篇 |
2013年 | 67篇 |
2012年 | 105篇 |
2011年 | 85篇 |
2010年 | 45篇 |
2009年 | 45篇 |
2008年 | 97篇 |
2007年 | 98篇 |
2006年 | 75篇 |
2005年 | 71篇 |
2004年 | 62篇 |
2003年 | 63篇 |
2002年 | 50篇 |
2001年 | 25篇 |
2000年 | 34篇 |
1999年 | 19篇 |
1998年 | 24篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 9篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有1316条查询结果,搜索用时 515 毫秒
81.
82.
Four rats were exposed to two different tone frequencies, each tone being correlated with independent probabilities of water delivery in a temporally defined schedule. The schedule consisted of a 60-s T cycle, with 30-s t(D) and t(Delta) succesive subcycles. t(D) and t(Delta) were assigned complementary probabilities of water delivery (1.0-0, 0.75-0.25, 0.5-0.5 and 1.0-0) in succesive phases. Each of the first three experimental phases was followed by five consecutive probe sessions using the same probability values, and in which water was delivered independently of responding at the end of each subcycle. Three additional rats were exposed to the same conditions, except that only one tone was used in t(D) and t(Delta). The highest frequencies of responding were observed in two of the rats exposed to differential tone frequencies, an effect that was correlated with lower percentages of lost water deliveries, shorter response latencies, and less variability in the intervals between successive water presentations. In the last phase in which probabilities of water delivery in t(D) and t(Delta) were 1.0 and 0, respectively, response frequency was always higher in t(Delta). These results suggest that the number of water deliveries obtained in the early cycles of every session were responsible for the total number of responses and its correlated effects. 相似文献
83.
Characterization of a zebra mutant of rice with increased susceptibility to light stress 总被引:6,自引:0,他引:6
The rice zebra mutant TCM248 is a single recessive mutant. This mutant develops transverse-striped leaves with green and white sectors under alternate light/dark growth conditions. Mutants that were grown under a higher light intensity during the light period showed a more intense striped phenotype. The white tissues contained abnormal chloroplasts with few internal membrane structures, while the green tissues in the mutants contained normal chloroplasts. The white tissue contained only trace amounts of Chls and carotenoids, and mRNA accumulation of nuclear genes encoding chloroplast proteins (rbcS, cab) was strongly suppressed compared to that in the wild type plants. A series of growth condition shift experiments demonstrated that the mutant displayed the striped phenotype only if it was exposed to the alternate light/dark growth conditions during a limited stage of early leaf development. These data suggest that the zebra gene is involved in the acquisition of photoprotective capacity of the plants and that this gene functions at an early stage of chloroplast differentiation. 相似文献
84.
Tohno Y Takano Y Tohno S Moriwake Y Minami T Takakura Y Yuri K 《Biological trace element research》2000,74(1):1-9
To elucidate changes of human tendons with aging, the authors studied age-related changes of elements in human Achilles’ tendons
by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of seven men and seven women, ranging in
age from 61 to 97 yr. It was found that the content of calcium increased progressively with aging in the Achilles’ tendons,
whereas the contents of phosphorus and magnesium decreased gradually with aging. The previous investigations demonstrated
that the content of calcium and phosphorus increased progressively with aging in most, but not all, human tissues, except
for the bones. In ligaments, such as the anterior cruciate ligament and the ligament of the head of the femur, which are histologically
similar to the Achilles’ tendon, it was previously found that both the contents of calcium and phosphorus increased with aging
in the ligaments. It should be noted that the content of phosphorus in the Achilles’ tendons decreased during the aging process.
In addition, it was found that there was a very high direct correlation between phosphorus and magnesium contents in the tendons,
but not between calcium and phosphorus contents. 相似文献
85.
Tateyama Y Takano Y Tohno Y Moriwake Y Tohno S Hashimoto M Araki T 《Biological trace element research》2000,74(3):211-221
To show the relationships of calcium accumulation in the thoracic aorta to the other tissues, calcium contents were determined
with a microwave-induced plasma-atomic emission spectrometer on arteries, veins, cartilages, ligaments, and bones. These tissues
were resected from 18 individuals, consisting of 11 men and 7 women who died in the age range 59–91 yr. As thoracic and abdominal
aortas are routinely used for radiographic examination of arterial calcification, they appear to be standard tissues of the
calcium accumulation. The calcium accumulations were determined in the femoral artery, the superior and inferior venae cavae,
the internal jugular vein, cartilages of the articular disk of the temporomandibular joint and the intervertebral disk, both
the ligaments of the anterior cruciate ligament and the ligamentum capitis femoris, and the calcaneus, in contrast with the
thoracic aorta.
As calcium increased in the thoracic aorta, it increased in the femoral artery, the articular disk of the temporomandibular
joint, the intervertebral disk, both ligaments of the anterior cruciate ligament, and the ligamentum capitis femoris, but
it did not increase in veins, such as the superior and inferior venae cavae and the internal jugular vein. In contrast, it
decreased in the calcaneus. 相似文献
86.
87.
A New System for Stringent, High-Titer Vesicular Stomatitis Virus G Protein-Pseudotyped Retrovirus Vector Induction by Introduction of Cre Recombinase into Stable Prepackaging Cell Lines 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
88.
Yumi Moriwake Yoshiyuki Tohno Setsuko Tohno Takeshi Minami Masako Utsumi Fumio Nishiwaki Masa-oki Yamada Hiroshi Yamamoto Yuko Okazaki Tadashi Fujii Yoshinori Takakura 《Biological trace element research》1998,64(1-3):229-235
The relative contents (RCs) of elements in the human menisci from 23 subjects in the age range between 65 and 93 yr were analyzed
by inductively coupled plasma atomic emission spectrometry. The RCs of sulfur, calcium, and phosphorus in menisci increased
progressively until the 80s, being the highest in the 80s, and thereafter decreased. The RCs of magnesium in menisci increased
progressively until the 90s. Regarding the medial and lateral menisci, higher RCs of magnesium and iron, and a lower RC of
phosphorus were found in lateral menisci in comparison with those in medial menisci.
There were sexual differences in the RCs of calcium and phosphorus of medial and lateral menisci. The RCs of calcium and phosphorus
were about 50% higher in women’s menisci than in men’s. Histological examinations showed that structureless mucoid masses
were observed in the menisci, with very high RCs of calcium and phosphorus being detected. 相似文献
89.
Soji Morishita Kochi Takahashi Marito Araki Yumi Hironaka Yoshitaka Sunami Yoko Edahiro Miyuki Tsutsui Akimichi Ohsaka Satoshi Tsuneda Norio Komatsu 《PloS one》2015,10(3)
Detection of the JAK2V617F mutation is essential for diagnosing patients with classical myeloproliferative neoplasms (MPNs). However, detection of the low-frequency JAK2V617F mutation is a challenging task due to the necessity of discriminating between true-positive and false-positive results. Here, we have developed a highly sensitive and accurate assay for the detection of JAK2V617F and named it melting curve analysis after T allele enrichment (MelcaTle). MelcaTle comprises three steps: 1) two cycles of JAK2V617F allele enrichment by PCR amplification followed by BsaXI digestion, 2) selective amplification of the JAK2V617F allele in the presence of a bridged nucleic acid (BNA) probe, and 3) a melting curve assay using a BODIPY-FL-labeled oligonucleotide. Using this assay, we successfully detected nearly a single copy of the JAK2V617F allele, without false-positive signals, using 10 ng of genomic DNA standard. Furthermore, MelcaTle showed no positive signals in 90 assays screening healthy individuals for JAK2V617F. When applying MelcaTle to 27 patients who were initially classified as JAK2V617F-positive on the basis of allele-specific PCR analysis and were thus suspected as having MPNs, we found that two of the patients were actually JAK2V617F-negative. A more careful clinical data analysis revealed that these two patients had developed transient erythrocytosis of unknown etiology but not polycythemia vera, a subtype of MPNs. These findings indicate that the newly developed MelcaTle assay should markedly improve the diagnosis of JAK2V617F-positive MPNs. 相似文献
90.
Mariana Malzoni Furtado Solange Maria Gennari Cassia Yumi Ikuta Anah Tereza de Almeida Jácomo Zenaide Maria de Morais Hilda Fátima de Jesus Pena Grasiela Edith de Oliveira Porfírio Leandro Silveira Rahel Sollmann Gisele Oliveira de Souza Natália Mundim T?rres José Soares Ferreira Neto 《PloS one》2015,10(11)
This study investigated the exposure of jaguar populations and domestic animals to smooth Brucella, Leptospira spp. and Toxoplasma gondii in the Cerrado, Pantanal and Amazon biomes of Brazil. Between February 2000 and January 2010, serum samples from 31 jaguars (Panthera onca), 1,245 cattle (Bos taurus), 168 domestic dogs (Canis lupus familiaris) and 29 domestic cats (Felis catus) were collected and analysed by rose bengal test for smooth Brucella, microscopic agglutination test for Leptospira spp. and modified agglutination test for T. gondii. Cattle populations from all sites (9.88%) were exposed to smooth Brucella, but only one jaguar from Cerrado was exposed to this agent. Jaguars captured in the Cerrado (60.0%) and in the Pantanal (45.5%) were seropositive for different serovars of Leptospira spp., cattle (72.18%) and domestic dogs (13.1%) from the three sites and one domestic cat from Pantanal were also seropositive for the agent. The most prevalent serotype of Leptospira spp. identified in jaguars from the Cerrado (Grippotyphosa) and the Pantanal (Pomona) biomes were distinct from those found in the domestic animals sampled. Jaguars (100%), domestic dogs (38.28%) and domestic cats (82.76%) from the three areas were exposed to T. gondii. Our results show that brucellosis and leptospirosis could have been transmitted to jaguars by domestic animals; and jaguars probably play an important role in the maintenance of T. gondii in nature. 相似文献