全文获取类型
收费全文 | 2379篇 |
免费 | 143篇 |
专业分类
2522篇 |
出版年
2023年 | 5篇 |
2022年 | 25篇 |
2021年 | 48篇 |
2020年 | 14篇 |
2019年 | 41篇 |
2018年 | 39篇 |
2017年 | 29篇 |
2016年 | 55篇 |
2015年 | 91篇 |
2014年 | 116篇 |
2013年 | 133篇 |
2012年 | 191篇 |
2011年 | 172篇 |
2010年 | 107篇 |
2009年 | 84篇 |
2008年 | 184篇 |
2007年 | 140篇 |
2006年 | 133篇 |
2005年 | 147篇 |
2004年 | 140篇 |
2003年 | 130篇 |
2002年 | 137篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 22篇 |
1998年 | 28篇 |
1997年 | 22篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 19篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有2522条查询结果,搜索用时 15 毫秒
71.
Akihiro Ohyama Junko Toyomura Toshiaki Tachibana Seiji Isonishi Haruka Takahashi Hiroshi Ishikawa 《Human cell》2016,29(4):188-196
A cell line, designated NOCC, was established from the ascites of a patient with clear cell adenocarcinoma of the ovary. The cell line has been grown without interruption and continuously propagated by serial passaging (more than 76 times) over 7 years. The cells are spherical to polygonal-shaped, display neoplastic, and pleomorphic features, and grow in a jigsaw puzzle-like pattern while forming monolayers without contact inhibition. The cells proliferate rapidly, but are easily floated as a cell sheet. The population doubling time is about 29 h. The number of chromosomes ranges from 60 to 83. The modal number of chromosomes is 70–74 at the 30th passage. NOCC cells secreted 750.5 ng/ml of VEGF over 3 days of culture. Hypoxia inducible factor-1α (HIF-1α) is a primary regulator of VEGF under hypoxic conditions. NOCC cells were not sensitive to the anticancer drugs BEV, DOX, GEM, ETP, CDDP, or TXT. The graft of NOCC cells to a scid mouse displayed similar histological aspects to the original tumor. Both the NOCC cells and the graft of the NOCC cells gave a positive PAS reaction. 相似文献
72.
73.
Belle MD Pattison EF Cheunsuang O Stewart A Kramer I Sigrist M Arber S Morris R 《Genesis (New York, N.Y. : 2000)》2007,45(11):679-688
In this study, transgenic mice in which membrane-linked enhanced green fluorescent protein (mGFP) is expressed from the Thy1.2 promoter were used. In these mice, a subpopulation of small to medium sized DRG neurons double stained for IB4 but not for CGRP. Most of the peripheral terminals traversed the dermis and ramify within the epidermis and form superficial terminals. Within the spinal cord, these afferents terminated exclusively within the substantia gelatinosa (SG). A second fibre type in the skin also expressed mGFP, and formed club-shaped endings towards the bases of hairs. Injury to the sciatic nerve resulted in mGFP loss from the SG ipsilateral to the nerve injury, but also in the corresponding region contralaterally. Together, these findings reveal the specificity of connectivity of a defined subpopulation of DRG sensory neurons innervating the epidermis and this will facilitate analysis of their physiological functions. 相似文献
74.
Smith I Broos A de Jong C Zeddeman A Smith C Smith G Moore F Barr J Crameri G Marsh G Tachedjian M Yu M Kung YH Wang LF Field H 《PloS one》2011,6(9):e25275
Hendra virus (HeV) causes a zoonotic disease with high mortality that is transmitted to humans from bats of the genus Pteropus (flying foxes) via an intermediary equine host. Factors promoting spillover from bats to horses are uncertain at this time, but plausibly encompass host and/or agent and/or environmental factors. There is a lack of HeV sequence information derived from the natural bat host, as previously sequences have only been obtained from horses or humans following spillover events. In order to obtain an insight into possible variants of HeV circulating in flying foxes, collection of urine was undertaken in multiple flying fox roosts in Queensland, Australia. HeV was found to be geographically widespread in flying foxes with a number of HeV variants circulating at the one time at multiple locations, while at times the same variant was found circulating at disparate locations. Sequence diversity within variants allowed differentiation on the basis of nucleotide changes, and hypervariable regions in the genome were identified that could be used to differentiate circulating variants. Further, during the study, HeV was isolated from the urine of flying foxes on four occasions from three different locations. The data indicates that spillover events do not correlate with particular HeV isolates, suggesting that host and/or environmental factors are the primary determinants of bat-horse spillover. Thus future spillover events are likely to occur, and there is an on-going need for effective risk management strategies for both human and animal health. 相似文献
75.
MicroRNA (miR)-17-92a expression plays a crucial role in lymphocyte ontogeny. We therefore set out to determine miR-92a expression levels in peripheral blood lymphocytes from healthy subjects to ascertain any association between these levels and ageing. We found a positive correlation between the miR-92a expression level and the percentages of RO-CD8+CD27+ (P = 0.0046) and CD3+CD8+CD62L+ (P = 0.0011). This suggests that the majority of miR-92a of CD8+ T cells is derived from naïve cells, and the miR-92a expression level in CD8+ T cells declines progressively with age. These results indicate that the age-related attrition of naïve T cells is linked to a reduction of miR-92a in human T -lymphocytes. Therefore, we should careful attention when evaluating human miRNA levels in T lymphocytes to use normal control values. 相似文献
76.
Hidehiro Hayashi Junko Ishikawa-Sakurai Mari Murai-Hatano Arifa Ahamed Matsuo Uemura 《Bioscience, biotechnology, and biochemistry》2013,77(9):1422-1429
During rice grain filling, grain moisture content and weight show dynamic changes. We focused on the expression of all 33 rice aquaporins in developing grains. Only two aquaporin genes, OsPIP2;1 and OsTIP3;1, were highly expressed in the period 10–25 days after heading (DAH). High-temperature treatment from 7 to 21 DAH abolished the dynamic up-regulation of OsPIP2;1 in the period 15–20 DAH, whereas OsTIP3;1 expression was not affected. Immunohistochemical analysis revealed that OsPIP2;1 was present in the starchy endosperm, nucellar projection, nucellar epidermis, and dorsal vascular bundles, but not in the aleurone layer. OsTIP3;1 was present in the aleurone layer and starchy endosperm. Water transport activity of recombinant OsTIP3;1 was low, in contrast to the high activity of recombinant OsPIP2;1 we reported previously. Our data suggest that OsPIP2;1 and OsTIP3;1 have distinct roles in developing grains. 相似文献
77.
78.
Highly mobile marine species in areas with no obvious geographic barriers are expected to show low levels of genetic differentiation. However, small‐scale variation in habitat may lead to resource polymorphisms and drive local differentiation by adaptive divergence. Using nuclear microsatellite genotyping at 20 loci, and mitochondrial control region sequencing, we investigated fine‐scale population structuring of inshore bottlenose dolphins (Tursiops aduncus) inhabiting a range of habitats in and around Moreton Bay, Australia. Bayesian structure analysis identified two genetic clusters within Moreton Bay, with evidence of admixture between them (FST = 0.05, P = 0.001). There was only weak isolation by distance but one cluster of dolphins was more likely to be found in shallow southern areas and the other in the deeper waters of the central northern bay. In further analysis removing admixed individuals, southern dolphins appeared genetically restricted with lower levels of variation (AR = 3.252, π = 0.003) and high mean relatedness (r = 0.239) between individuals. In contrast, northern dolphins were more diverse (AR = 4.850, π = 0.009) and were mixing with a group of dolphins outside the bay (microsatellite‐based STRUCTURE analysis), which appears to have historically been distinct from the bay dolphins (mtDNA ΦST = 0.272, P < 0.001). This study demonstrates the ability of genetic techniques to expose fine‐scale patterns of population structure and explore their origins and mechanisms. A complex variety of inter‐related factors including local habitat variation, differential resource use, social behaviour and learning, and anthropogenic disturbances are likely to have played a role in driving fine‐scale population structure among bottlenose dolphins in Moreton Bay. 相似文献
79.
80.
Gregan J Riedel CG Petronczki M Cipak L Rumpf C Poser I Buchholz F Mechtler K Nasmyth K 《Nature protocols》2007,2(5):1145-1151
Tandem affinity purification (TAP) is a generic two-step affinity purification protocol for isolation of TAP-tagged proteins together with associated proteins. We used bacterial artificial chromosome to heterologously express TAP-tagged murine Sgo1 protein in human HeLa cells. This allowed us to test the functionality of the Sgo1-TAP protein by RNA interference-mediated depletion of the endogenous human Sgo1. Here, we present an optimized protocol for purification of TAP-tagged Sgo1 protein as well as KIAA1387 from HeLa cells with detailed instructions. The purification protocol can be completed in 1 day and it should be applicable to other proteins. 相似文献