全文获取类型
收费全文 | 10999篇 |
免费 | 861篇 |
国内免费 | 8篇 |
专业分类
11868篇 |
出版年
2022年 | 59篇 |
2021年 | 97篇 |
2020年 | 52篇 |
2019年 | 88篇 |
2018年 | 130篇 |
2017年 | 145篇 |
2016年 | 197篇 |
2015年 | 348篇 |
2014年 | 378篇 |
2013年 | 516篇 |
2012年 | 619篇 |
2011年 | 648篇 |
2010年 | 437篇 |
2009年 | 435篇 |
2008年 | 578篇 |
2007年 | 663篇 |
2006年 | 629篇 |
2005年 | 630篇 |
2004年 | 609篇 |
2003年 | 610篇 |
2002年 | 618篇 |
2001年 | 140篇 |
2000年 | 134篇 |
1999年 | 173篇 |
1998年 | 215篇 |
1997年 | 163篇 |
1996年 | 143篇 |
1995年 | 140篇 |
1994年 | 131篇 |
1993年 | 154篇 |
1992年 | 176篇 |
1991年 | 132篇 |
1990年 | 143篇 |
1989年 | 114篇 |
1988年 | 96篇 |
1987年 | 92篇 |
1986年 | 69篇 |
1985年 | 113篇 |
1984年 | 102篇 |
1983年 | 78篇 |
1982年 | 97篇 |
1981年 | 83篇 |
1980年 | 75篇 |
1979年 | 75篇 |
1978年 | 60篇 |
1977年 | 75篇 |
1976年 | 69篇 |
1975年 | 46篇 |
1974年 | 46篇 |
1973年 | 50篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Elinor McKone Sacha Stokes Jia Liu Sarah Cohan Chiara Fiorentini Madeleine Pidcock Galit Yovel Mary Broughton Michel Pelleg 《PloS one》2012,7(10)
Other-race and other-ethnicity effects on face memory have remained a topic of consistent research interest over several decades, across fields including face perception, social psychology, and forensic psychology (eyewitness testimony). Here we demonstrate that the Cambridge Face Memory Test format provides a robust method for measuring these effects. Testing the Cambridge Face Memory Test original version (CFMT-original; European-ancestry faces from Boston USA) and a new Cambridge Face Memory Test Chinese (CFMT-Chinese), with European and Asian observers, we report a race-of-face by race-of-observer interaction that was highly significant despite modest sample size and despite observers who had quite high exposure to the other race. We attribute this to high statistical power arising from the very high internal reliability of the tasks. This power also allows us to demonstrate a much smaller within-race other ethnicity effect, based on differences in European physiognomy between Boston faces/observers and Australian faces/observers (using the CFMT-Australian). 相似文献
82.
Thi Thuy Duong Michel Coste Agnès Feurtet-Mazel Dinh Kim Dang Caroline Gold Young Seuk Park Alain Boudou 《Hydrobiologia》2006,563(1):201-216
The effects of urban pollution from Hanoi city on the benthic diatom communities of the Nhue–Tolich river system were studied
during the 2003 dry season. Benthic diatoms were allowed to grow on glass slides suspended in the water flow for 4 weeks.
To reveal the relationship between water quality and diatom communities, Canonical correspondence analysis (CCA) was used
on data concerning relative abundances of diatom species and environmental variables. Two diatom indices, IPS and DAIpo, were
applied to evaluate water quality in the three rivers. A total of 291 diatom taxa were found in the Red, Nhue and Tolich Rivers.
These were mainly cosmopolitan taxa, with some tropical, subtropical and endemic taxa. The most abundant taxa at the Red site
were Aulacoseira granulata, Achnanthidium minutissimum, Encyonema minutum, Navicula recens and other halophilous taxa such as Nitzschia kurzii, Seminavis strigosa, Entomoneis paludosa, Bacillaria paradoxa. Diatom assemblages at the Tolich site consisted mainly of Nitzschia umbonata, Nitzschia palea and Eolimna minima. Diatom density ranged from 660 to 30,000 cells/cm2. Environmental variables and diatom assemblage composition at all sites were significantly correlated. Two diatom indices
gave similar results and indicate the Tolich River with the lowest values as a highly polluted site. 相似文献
83.
Sophie Calderari Massimiliano Ria Christelle Gérard Tatiane C. Nogueira Olatz Villate Stephan C. Collins Helen Neil Nicolas Gervasi Christophe Hue Nicolas Suarez-Zamorano Cécilia Prado Miriam Cnop Marie-Thérèse Bihoreau Pamela J. Kaisaki Jean-Baptiste Cazier Cécile Julier Mark Lathrop Michel Werner Dominique Gauguier 《Genomics》2018,110(2):98-111
The GLIS family zinc finger 3 isoform (GLIS3) is a risk gene for Type 1 and Type 2 diabetes, glaucoma and Alzheimer's disease endophenotype. We identified GLIS3 binding sites in insulin secreting cells (INS1) (FDR q < 0.05; enrichment range 1.40–9.11 fold) sharing the motif wrGTTCCCArTAGs, which were enriched in genes involved in neuronal function and autophagy and in risk genes for metabolic and neuro-behavioural diseases. We confirmed experimentally Glis3-mediated regulation of the expression of genes involved in autophagy and neuron function in INS1 and neuronal PC12 cells. Naturally-occurring coding polymorphisms in Glis3 in the Goto-Kakizaki rat model of type 2 diabetes were associated with increased insulin production in vitro and in vivo, suggestive alteration of autophagy in PC12 and INS1 and abnormal neurogenesis in hippocampus neurons. Our results support biological pleiotropy of GLIS3 in pathologies affecting β-cells and neurons and underline the existence of trans?nosology pathways in diabetes and its co-morbidities. 相似文献
84.
Malia M. Edwards Elmina Mammadova-Bach Fabien Alpy Annick Klein Wanda L. Hicks Michel Roux Patricia Simon-Assmann Richard S. Smith Gertraud Orend Jiang Wu Neal S. Peachey J��rgen K. Naggert Olivier Lefebvre Patsy M. Nishina 《The Journal of biological chemistry》2010,285(10):7697-7711
The Neuromutagenesis Facility at the Jackson Laboratory generated a mouse model of retinal vasculopathy, nmf223, which is characterized clinically by vitreal fibroplasia and vessel tortuosity. nmf223 homozygotes also have reduced electroretinogram responses, which are coupled histologically with a thinning of the inner nuclear layer. The nmf223 locus was mapped to chromosome 17, and a missense mutation was identified in Lama1 that leads to the substitution of cysteine for a tyrosine at amino acid 265 of laminin α1, a basement membrane protein. Despite normal localization of laminin α1 and other components of the inner limiting membrane, a reduced integrity of this structure was suggested by ectopic cells and blood vessels within the vitreous. Immunohistochemical characterization of nmf223 homozygous retinas demonstrated the abnormal migration of retinal astrocytes into the vitreous along with the persistence of hyaloid vasculature. The Y265C mutation significantly reduced laminin N-terminal domain (LN) interactions in a bacterial two-hybrid system. Therefore, this mutation could affect interactions between laminin α1 and other laminin chains. To expand upon these findings, a Lama1 null mutant, Lama1tm1.1Olf, was generated that exhibits a similar but more severe retinal phenotype than that seen in nmf223 homozygotes. The increased severity of the Lama1 null mutant phenotype is probably due to the complete loss of the inner limiting membrane in these mice. This first report of viable Lama1 mouse mutants emphasizes the importance of this gene in retinal development. The data presented herein suggest that hypomorphic mutations in human LAMA1 could lead to retinal disease. 相似文献
85.
Michel M. Dugon Luke Hayden Alexander Black Wallace Arthur 《Evolution & development》2012,14(6):515-521
In contrast to previous claims that (a) there is a law of recapitulation and, conversely, (b) recapitulation never happens, the evolutionary repatterning of development can take many forms, of which recapitulation is one. Here, we add another example to the list of case studies of recapitulation. This example involves the development of the venom claws (forcipules) in the centipede Scolopendra subspinipes mutilans, and in particular the development of the duct through which venom flows from the gland that produces it (proximal) to the opening called the meatus (distal) through which it is injected into prey. Most of the information we present is from early postembryonic stages—these have been neglected in previous work on centipede development. We show that the venom ducts arise from sutures that are invaginations of the cuticle. In S. s. mutilans, the invagination in each forcipule forms into a tubular structure that detaches itself from the exoskeleton and moves toward the center of the forcipule. This is in contrast to extant Scutigera, and also, probably, Scolopendra's extinct Scutigera‐like ancestors, where the duct remains attached to the cuticle of throughout development. Thus, S. s. mutilans exhibits a recapitulatory repatterning of development. 相似文献
86.
Morange M 《Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences》2011,42(1):69-74
The modern synthesis has been considered to be wrongly called a "synthesis", since it had completely excluded embryology, and many other disciplines. The recent developments of Evo-Devo have been seen as a step in the right direction, as complementing the modern synthesis, and probably leading to a "new synthesis". My argument is that the absence of embryology from the modern synthesis was the visible sign of a more profound lack: the absence of functional biology in the evolutionary synthesis. I will consider the reasons for this absence, as well as the recent transformations which favoured a closer interaction between these two branches of biology. Then I will describe two examples of recent work in which functional and evolutionary questioning were tightly linked. The most significant part of the paper will be devoted to the transformation of evolutionary theory that can be expected from this encounter: a deep transformation, or simply an experimental confirmation of this theory? I will not choose between these two different possibilities, but will discuss some of the difficulties which make the choice problematic. 相似文献
87.
88.
89.
Michel Lagarde Marc Dechavanne Michel Rigaud Jacqueline Durand 《Prostaglandins & other lipid mediators》1979,17(5):685-705
Radioimmunoassays of platelet prostaglandins E1 and F1α in platelet rich plasma or platelet suspension, demonstrate that both PGE1 and PGF1α are present at higher concentrations than prostaglandins E2 and F2α. Gas chromatography — mass spectrometry determinations of prostaglandins E1 and E2 in resting washed platelets confirm this difference. Lastly, there is a greater incorporation of [1-14C] acetate into prostaglandins E1 and F1α compared to that into prostaglandins E2 and F2α. 相似文献
90.
Clermont E. Dionne Renée Bourbonnais Pierre Frémont Michel Rossignol Susan R. Stock Isabelle Larocque 《CMAJ》2005,172(12):1559-1567
Background
Tools for early identification of workers with back pain who are at high risk of adverse occupational outcome would help concentrate clinical attention on the patients who need it most, while helping reduce unnecessary interventions (and costs) among the others. This study was conducted to develop and validate clinical rules to predict the 2-year work disability status of people consulting for nonspecific back pain in primary care settings.Methods
This was a 2-year prospective cohort study conducted in 7 primary care settings in the Quebec City area. The study enrolled 1007 workers (participation, 68.4% of potential participants expected to be eligible) aged 18–64 years who consulted for nonspecific back pain associated with at least 1 day''s absence from work. The majority (86%) completed 5 telephone interviews documenting a large array of variables. Clinical information was abstracted from the medical files. The outcome measure was “return to work in good health” at 2 years, a variable that combined patients'' occupational status, functional limitations and recurrences of work absence. Predictive models of 2-year outcome were developed with a recursive partitioning approach on a 40% random sample of our study subjects, then validated on the rest.Results
The best predictive model included 7 baseline variables (patient''s recovery expectations, radiating pain, previous back surgery, pain intensity, frequent change of position because of back pain, irritability and bad temper, and difficulty sleeping) and was particularly efficient at identifying patients with no adverse occupational outcome (negative predictive value 78%– 94%).Interpretation
A clinical prediction rule accurately identified a large proportion of workers with back pain consulting in a primary care setting who were at a low risk of an adverse occupational outcome.Since the 1950s, back pain has taken on the proportions of a veritable epidemic, counting now among the 5 most frequent reasons for visits to physicians'' offices in North America1,2,3 and ranking sixth among health problems generating the highest direct medical costs.4 Because of its high incidence and associated expense, effective intervention for back pain has great potential for improving population health and for freeing up extensive societal resources.So-called red flags to identify pain that is specific (i.e., pain in the back originating from tumours, fractures, infections, cauda equina syndrome, visceral pain and systemic disease)5 account for about 3% of all cases of back pain.6 The overwhelming majority of back-pain problems are thus nonspecific. One important feature of nonspecific back pain among workers is that a small proportion of cases (< 10%) accounts for most of the costs (> 70%).7,8,9,10,11,12,13,14 This fact has led investigators to focus on the early identification of patients who are at higher risk of disability, so that specialized interventions can be provided earlier, whereas other patients can be expected to recover with conservative care.9,15,16,17,18,19,20,21,22,23,24,25 Although this goal has become much sought-after in back-pain research, most available studies in this area have 3 methodological problems:- Potential predictors are often limited to administrative or clinical data, whereas it is clear that back pain is a multidimensional health problem.
- The outcome variable is most often a 1-point dichotomous measure of return to work, time off work or duration of compensation, although some authors have warned against the use of first return to work as a measure of recovery. Baldwin and colleagues,26 for instance, point out that first return to work is frequently followed by recurrences of work absence.
- Most published prediction rules developed for back pain have not been successfully validated on any additional samples of patients.