全文获取类型
收费全文 | 4274篇 |
免费 | 416篇 |
国内免费 | 1篇 |
出版年
2023年 | 15篇 |
2021年 | 63篇 |
2020年 | 32篇 |
2019年 | 39篇 |
2018年 | 44篇 |
2017年 | 53篇 |
2016年 | 91篇 |
2015年 | 176篇 |
2014年 | 203篇 |
2013年 | 260篇 |
2012年 | 285篇 |
2011年 | 300篇 |
2010年 | 197篇 |
2009年 | 161篇 |
2008年 | 242篇 |
2007年 | 230篇 |
2006年 | 248篇 |
2005年 | 242篇 |
2004年 | 241篇 |
2003年 | 214篇 |
2002年 | 205篇 |
2001年 | 78篇 |
2000年 | 59篇 |
1999年 | 82篇 |
1998年 | 79篇 |
1997年 | 48篇 |
1996年 | 46篇 |
1995年 | 47篇 |
1994年 | 44篇 |
1993年 | 37篇 |
1992年 | 41篇 |
1991年 | 28篇 |
1990年 | 35篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1986年 | 17篇 |
1985年 | 25篇 |
1984年 | 41篇 |
1983年 | 33篇 |
1982年 | 24篇 |
1981年 | 28篇 |
1980年 | 23篇 |
1979年 | 18篇 |
1978年 | 21篇 |
1977年 | 16篇 |
1976年 | 20篇 |
1975年 | 21篇 |
1974年 | 22篇 |
1969年 | 14篇 |
排序方式: 共有4691条查询结果,搜索用时 78 毫秒
1.
2.
3.
Sight is undoubtedly important for finding and appreciating food, and cooking. Blind individuals are strongly impaired in finding food, limiting the variety of flavours they are exposed to. We have shown before that compared to sighted controls, congenitally blind individuals have enhanced olfactory but reduced taste perception. In this study we tested the hypothesis that congenitally blind subjects have enhanced orthonasal but not retronasal olfactory skills. Twelve congenitally blind and 14 sighted control subjects, matched in age, gender and body mass index, were asked to identify odours using grocery-available food powders. Results showed that blind subjects were significantly faster and tended to be better at identifying odours presented orthonasally. This was not the case when odorants were presented retronasally. We also found a significant group x route interaction, showing that although both groups performed better for retronasally compared to orthonasally presented odours, this gain was less pronounced for blind subjects. Finally, our data revealed that blind subjects were more familiar with the orthonasal odorants and used the retronasal odorants less often for cooking than their sighted counterparts. These results confirm that orthonasal but not retronasal olfactory perception is enhanced in congenital blindness, a result that is concordant with the reduced food variety exposure in this group. 相似文献
4.
Paul C. Marker Jennifer A. King Neal G. Copeland Nancy A. Jenkins David M. Kingsley 《Genomics》1995,28(3)
Murine Bmp7 has been assigned to distal Chromosome 2 by interspecific backcross mapping. The map location suggests close linkage to classical mouse mutations and places Bmp7 within a chromosome region thought to contain one or more unidentified imprinted genes. A direct test suggests that Bmp7 is not imprinted. An examination of embryonic RNA expression patterns shows that Bmp7 is expressed in a variety of skeletal and nonskeletal tissues. Both embryonic expression patterns and the human chromosomal sublocalization inferred from its mouse location make Bmp7 a candidate for the gene affected in some patients with Holt-Oram syndrome. 相似文献
5.
Reuben S.E. Young Andrew P. Bowman Kaylyn D. Tousignant Berwyck L.J. Poad Jennifer H. Gunter Lisa K. Philp Colleen C. Nelson Shane R. Ellis Ron M.A. Heeren Martin C. Sadowski Stephen J. Blanksby 《Journal of lipid research》2022,63(6):100223
The cellular energy and biomass demands of cancer drive a complex dynamic between uptake of extracellular FAs and their de novo synthesis. Given that oxidation of de novo synthesized FAs for energy would result in net-energy loss, there is an implication that FAs from these two sources must have distinct metabolic fates; however, hitherto, all FAs have been considered part of a common pool. To probe potential metabolic partitioning of cellular FAs, cancer cells were supplemented with stable isotope-labeled FAs. Structural analysis of the resulting glycerophospholipids revealed that labeled FAs from uptake were largely incorporated to canonical (sn-) positions on the glycerol backbone. Surprisingly, labeled FA uptake also disrupted canonical isomer patterns of the unlabeled lipidome and induced repartitioning of n-3 and n-6 PUFAs into glycerophospholipid classes. These structural changes support the existence of differences in the metabolic fates of FAs derived from uptake or de novo sources and demonstrate unique signaling and remodeling behaviors usually hidden from conventional lipidomics. 相似文献
6.
7.
Problem Infrequent presentation of patients with eclampsia, leading to staff inexperienced in the condition and untested emergency systems.Design “Fire drill” programme using on-site simulation of patients with eclampsia.Setting Tertiary referral obstetric unit.Key measures for improvement Successful implementation of measures to optimise management of eclampsia.Strategies for change Rapid activation of emergency team after one call, development and dissemination of evidence based protocol for eclampsia, strategically placed “eclampsia boxes,” individual staff feedback and education.Effects of change Efficient and appropriate management of subsequent simulated patients.Lessons learnt On-site simulation can identify and correct potential deficiencies in the care of patients with eclampsia. 相似文献
8.
Mirror carp were infected with Ichthyophthirius multifiliis (Fouquet) under standardized conditions. The size and number of parasites at selected sites on the body were recorded during the course of the infection. Initial exposure to 40 mature parasites resulted in a mild infection with 100% recovery after 18 days. Recovered fish did not appear to be carriers of the parasite. Exposure to 400 parasites resulted in 100% mortality between 22–25 days. The growth rate of the parasite was linear. Parasites were more numerous in the dorsal surface of the fish than in the lateral or ventral surface. The increase in parasite numbers during the disease was greater in the gills than in the skin. 相似文献
9.
Jin Wei Mia Madel Alfajaro Peter C. DeWeirdt Ruth E. Hanna William J. Lu-Culligan Wesley L. Cai Madison S. Strine Shang-Min Zhang Vincent R. Graziano Cameron O. Schmitz Jennifer S. Chen Madeleine C. Mankowski Renata B. Filler Neal G. Ravindra Victor Gasque Fernando J. de Miguel Ajinkya Patil Huacui Chen Craig B. Wilen 《Cell》2021,184(1):76-91.e13
10.
Cascade J. B. Sorte Ron J. Etter Robert Spackman Elizabeth E. Boyle Robyn E. Hannigan 《PloS one》2013,8(11)
As the climate warms, species that cannot tolerate changing conditions will only persist if they undergo range shifts. Redistribution ability may be particularly variable for benthic marine species that disperse as pelagic larvae in ocean currents. The blue mussel, Mytilus edulis, has recently experienced a warming-related range contraction in the southeastern USA and may face limitations to northward range shifts within the Gulf of Maine where dominant coastal currents flow southward. Thus, blue mussels might be especially vulnerable to warming, and understanding dispersal patterns is crucial given the species'' relatively long planktonic larval period (>1 month). To determine whether trace elemental “fingerprints” incorporated in mussel shells could be used to identify population sources (i.e. collection locations), we assessed the geographic variation in shell chemistry of blue mussels collected from seven populations between Cape Cod, Massachusetts and northern Maine. Across this ∼500 km of coastline, we were able to successfully predict population sources for over two-thirds of juvenile individuals, with almost 80% of juveniles classified within one site of their collection location and 97% correctly classified to region. These results indicate that significant differences in elemental signatures of mussel shells exist between open-coast sites separated by ∼50 km throughout the Gulf of Maine. Our findings suggest that elemental “fingerprinting” is a promising approach for predicting redistribution potential of the blue mussel, an ecologically and economically important species in the region. 相似文献