全文获取类型
收费全文 | 10387篇 |
免费 | 1207篇 |
国内免费 | 6篇 |
专业分类
11600篇 |
出版年
2023年 | 53篇 |
2022年 | 110篇 |
2021年 | 218篇 |
2020年 | 133篇 |
2019年 | 168篇 |
2018年 | 201篇 |
2017年 | 194篇 |
2016年 | 289篇 |
2015年 | 492篇 |
2014年 | 495篇 |
2013年 | 539篇 |
2012年 | 771篇 |
2011年 | 685篇 |
2010年 | 443篇 |
2009年 | 375篇 |
2008年 | 539篇 |
2007年 | 530篇 |
2006年 | 444篇 |
2005年 | 430篇 |
2004年 | 399篇 |
2003年 | 366篇 |
2002年 | 352篇 |
2001年 | 224篇 |
2000年 | 246篇 |
1999年 | 204篇 |
1998年 | 120篇 |
1997年 | 88篇 |
1996年 | 87篇 |
1995年 | 70篇 |
1994年 | 87篇 |
1993年 | 76篇 |
1992年 | 161篇 |
1991年 | 133篇 |
1990年 | 127篇 |
1989年 | 115篇 |
1988年 | 119篇 |
1987年 | 107篇 |
1986年 | 93篇 |
1985年 | 105篇 |
1984年 | 90篇 |
1983年 | 71篇 |
1982年 | 62篇 |
1981年 | 81篇 |
1980年 | 72篇 |
1979年 | 90篇 |
1978年 | 53篇 |
1977年 | 65篇 |
1976年 | 54篇 |
1975年 | 79篇 |
1974年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
Lorenzo Galluzzi Ilio Vitale Laura Senovilla Tobias Eisenberg Didac Carmona-Gutierrez Erika Vacchelli Thomas Robert Hugues Ripoche Nora J?gemann Caroline Paccard Nicolas Servant Philippe Hupé Vladimir Lazar Philippe Dessen Emmanuel Barillot Hans Zischka Frank Madeo Guido Kroemer 《Cell cycle (Georgetown, Tex.)》2012,11(18):3472-3480
192.
Ferruh Artunc Christian Mueller Tobias Breidthardt Raphael Twerenbold Andreas Peter Claus Thamer Peter Weyrich Hans-Ulrich Haering Bjoern Friedrich 《PloS one》2012,7(10)
Background
In hemodialysis patients, elevated plasma troponin concentrations are a common finding that has even increased with the advent of newly developed sensitive assays. However, the interpretation and relevance of this is still under debate.Methods
In this cross-sectional study, we analyzed plasma concentrations of sensitive troponin I (TnI) and troponin T (TnT) in stable ambulatory hemodialysis patients (n = 239) and investigated their associations with clinical factors and mortality.Results
In all of the enrolled patients, plasma TnI or TnT was detectable at a median concentration of 14 pg/ml (interquartile range: 7–29) using the Siemens TnI ultra assay and 49 pg/ml (31–74) using the Roche Elecsys high sensitive TnT assay. Markedly more patients exceeded the 99th percentile for TnT than for TnI (95% vs. 14%, p<0.0001). In a multivariate linear regression model, TnT was independently associated with age, gender, systolic dysfunction, time on dialysis, residual diuresis and systolic blood pressure, whereas TnI was independently associated with age, systolic dysfunction, pulse pressure, time on dialysis and duration of a HD session. During a follow-up period of nearly two years, TnT concentration above 38 pg/mL was associated with a 5-fold risk of death, whereas elevation of TnI had a gradual association to mortality.Conclusion
In hemodialysis patients, elevations of plasma troponin concentrations are explained by cardiac function and dialysis-related parameters, which contribute to cardiac strain. Both are highly predictive of increased risk of death. 相似文献193.
194.
An increasing number of broadly neutralizing monoclonal antibodies (bnMAb) against the HIV-1 envelope (Env) protein has been discovered recently. Despite this progress, vaccination efforts with the aim to re-elicit bnMAbs that provide protective immunity have failed so far. Herein, we describe the development of a mammalian cell based FACS-panning method in which bnMAbs are used as tools to select surface-exposed envelope variants according to their binding affinity. For that purpose, an HIV-1 derived lentiviral vector was developed to infect HEK293T cells at low multiplicity of infection (MOI) in order to link Env phenotype and genotype. For proof of principle, a gp145 Env model-library was established in which the complete V3 domain was substituted by five strain specific V3 loop sequences with known binding affinities to nMAb 447-52D, respectively. Env genes were recovered from selected cells by PCR, subcloned into a lentiviral vector (i) to determine and quantify the enrichment nMAb binders and (ii) to generate a new batch of transduction competent particles. After 2 selection cycles the Env variant with highest affinity was enriched 20-fold and represented 80% of the remaining Env population. Exploiting the recently described bnMAbs, this procedure might prove useful in selecting Env proteins from large Env libraries with the potential to elicit bnMAbs when used as vaccine candidates. 相似文献
195.
Kelsey H. Fisher-Wellman James A. Draper Michael T. Davidson Ashley S. Williams Tara M. Narowski Dorothy H. Slentz Olga R. Ilkayeva Robert D. Stevens Gregory R. Wagner Rami Najjar Mathew D. Hirschey J. Will Thompson David P. Olson Daniel P. Kelly Timothy R. Koves Paul A. Grimsrud Deborah M. Muoio 《Cell reports》2019,26(6):1557-1572.e8
196.
M.J. Dring A. Wagner L.A. Franklin R. Kuhlenkamp K. Lüning 《Helgoland Marine Research》2001,55(1):3-11
Ultraviolet (UV) radiation at four wavelengths (305, 320, 340 and 380 nm) and photosynthetically active radiation (PAR) were
measured from May 1994 to October 1999 using Biospherical UV radiometers. A surface reference sensor located on the roof of
the Marine Station at Helgoland recorded values every 5 min, and an equivalent profiling underwater sensor was used for measurements
in the sea at approximately monthly intervals. The ratio of 305-nm radiation to PAR varied seasonally, with a 14-fold increase
from winter to summer. A much weaker seasonal trend (ca. 1.5-fold) was apparent in the ratio of 320-nm radiation to PAR, but
there was no seasonal trend in the ratios of 340- or 380-nm radiation to PAR. The year-to-year variations in 305-nm radiation
were also much greater relative to PAR than for the other UV wavelengths, but there was no evidence of a change in the 305 nm:PAR
ratio over the study period. The ratios of both 305- and 320-nm radiation to PAR increased from dawn to midday, but those
of 340- and 380-nm radiation were almost constant through the day, except shortly before sunrise and after sunset when the
proportions of 340- and 380-nm radiation increased. Underwater measurements of PAR and UV suggest that the 1% depth for 305-nm
radiation was little more than 1 m, but this estimate is valid only for summer and autumn because, in other seasons, few reliable
readings for 305-nm radiation could be obtained underwater, and no attenuation coefficient could be calculated. The 1% depths
recorded for the other UV wavelengths in the middle 6 months of the year were 2.0 m for 320 nm, 2.6 m for 340 nm and 4.6 m
for 380 nm, compared with 12 m for PAR, but the attenuation of all wavebands increased sharply in October and remained higher
until March. An analysis of the influence of sun angle, total column ozone concentration, the proportion of skylight, and
cloud cover on the ratio of UV wavelengths to PAR in surface irradiance demonstrated that solar angle has a greater influence
than ozone concentration on the irradiance at 305 nm, and that the typical occurrence of ozone "holes" in spring may not result
in higher UV-B irradiances than occur under higher ozone concentrations in summer. The implications of the data for attempts
to model the biological effects of natural UV radiation on marine organisms are considered.
Received in revised form: 3 July 2000
Electronic Publication 相似文献
197.
198.
Anna Amcheslavsky Mona?L. Wood Andriy?V. Yeromin Ian Parker J.?Alfredo Freites Douglas?J. Tobias Michael?D. Cahalan 《Biophysical journal》2015,108(2):237-246
Upon endoplasmic reticulum Ca2+ store depletion, Orai channels in the plasma membrane are activated directly by endoplasmic reticulum-resident STIM proteins to generate the Ca2+-selective, Ca2+ release-activated Ca2+ (CRAC) current. After the molecular identification of Orai, a plethora of functional and biochemical studies sought to compare Orai homologs, determine their stoichiometry, identify structural domains responsible for the biophysical fingerprint of the CRAC current, identify the physiological functions, and investigate Orai homologs as potential therapeutic targets. Subsequently, the solved crystal structure of Drosophila Orai (dOrai) substantiated many findings from structure-function studies, but also revealed an unexpected hexameric structure. In this review, we explore Orai channels as elucidated by functional and biochemical studies, analyze the dOrai crystal structure and its implications for Orai channel function, and present newly available information from molecular dynamics simulations that shed light on Orai channel gating and permeation. 相似文献
199.
Stephan Wagner Smrutisanjita Behera Sara De Bortoli David C. Logan Philippe Fuchs Luca Carraretto Enrico Teardo Laura Cendron Thomas Nietzel Magdalena Fü?l Fabrizio G. Doccula Lorella Navazio Mark D. Fricker Olivier Van Aken Iris Finkemeier Andreas J. Meyer Ildikò Szabò Alex Costa Markus Schwarzl?nder 《The Plant cell》2015,27(11):3190-3212
Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca2+ signaling may play a central role in this process. Free Ca2+ dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca2+ dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca2+ uniporter machinery in mammals. MICU binds Ca2+ and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca2+ sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca2+ in the matrix. Furthermore, Ca2+ elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca2+ signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca2+ uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca2+ uptake by moderating influx, thereby shaping Ca2+ signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca2+ signaling in plants. 相似文献
200.
Robert Kaba Alhassan Edward Nketiah-Amponsah Nicole Spieker Daniel Kojo Arhinful Alice Ogink Paul van Ostenberg Tobias F. Rinke de Wit 《PloS one》2015,10(11)