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101.
Binford GJ Wells MA 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,135(1):25-33
The venoms of Loxosceles spiders cause severe dermonecrotic lesions in human tissues. The venom component sphingomyelinase D (SMD) is a contributor to lesion formation and is unknown elsewhere in the animal kingdom. This study reports comparative analyses of SMD activity and venom composition of select Loxosceles species and representatives of closely related Haplogyne genera. The goal was to identify the phylogenetic group of spiders with SMD and infer the timing of evolutionary origin of this toxin. We also preliminarily characterized variation in molecular masses of venom components in the size range of SMD. SMD activity was detected in all (10) Loxosceles species sampled and two species representing their sister taxon, Sicarius, but not in any other venoms or tissues surveyed. Mass spectrometry analyses indicated that all Loxosceles and Sicarius species surveyed had multiple (at least four to six) molecules in the size range corresponding to known SMD proteins (31-35 kDa), whereas other Haplogynes analyzed had no molecules in this mass range in their venom. This suggests SMD originated in the ancestors of the Loxosceles/Sicarius lineage. These groups of proteins varied in molecular mass across species with North American Loxosceles having 31-32 kDa, African Loxosceles having 32-33.5 kDa and Sicarius having 32-33 kDa molecules. 相似文献
102.
The song system of zebra finches is sexually dimorphic: the volumes of the song control nuclei and the neurons within these nuclei are larger in males. The song system of hatching female zebra finches is masculinized by systemic treatment with estrogen. We investigated the locus of this estrogen action by using microimplants of estradiol benzoate (EB). We implanted female zebra finch nestlings 10–13 days old with Silastic pellets containing approximately 2 μg EB at one of several sites: near the higher vocal center (HVC), in the brain distant from HVC, or in the periphery either under the skin of the breast or in the peritoneal cavity. Controls were either unimplanted or implanted near HVC with Silastic pellets without hormone. The brains were fixed by perfusion at 60 days, and the volumes of the song control regions as well as the sizes of individual neurons were measured. Neurons in HVC were lerger (more masculine) in the HVC-implanted group than in other groups, which did not differ among themselves. The size of neurons in the robust nucleus of the archistriatum (RA) and the lateral magnocellular nucleus ofthe neostriatum (lMAN) were inversely correlated with the distance of the EB pellet to HVC; neurons in RA and lMAN were larger when the EB pellets were closer to HVC. This result suggests that implants near HVC were at or near a site of estrogen action. To our knowledge, this is the first demonstration that localized brain implants of estrogen cause morphological masculinization in any species. 1994 John Wiley & Sons, Inc. 相似文献
103.
We investigated the role of the Ras/extracellular-regulated kinase (ERK) pathway in the development of tolerance to Delta(9)-tetrahydrocannabinol (THC)-induced reduction in spontaneous locomotor activity by a genetic (Ras-specific guanine nucleotide exchange factor (Ras-GRF1) knock-out mice) and pharmacological approach. Pre-treatment of wild-type mice with SL327 (50 mg/kg i.p.), a specific inhibitor of mitogen-activated protein kinase kinase (MEK), the upstream kinase of ERK, fully prevented the development of tolerance to THC-induced hypolocomotion. We investigated the impact of the inhibition of ERK activation on the biological processes involved in cannabinoid tolerance (receptor down-regulation and desensitization), by autoradiographic cannabinoid CB1 receptor and cannabinoid-stimulated [(35)S]GTPgammaS binding studies in subchronically treated mice (THC, 10 mg/kg s.c., twice a day for 5 days). In the caudate putamen and cerebellum of Ras-GRF1 knock-out mice and SL327 pre-treated wild-type mice, CB1 receptor down-regulation and desensitization did not occur, suggesting that ERK activation might account for CB1 receptor plasticity involved in the development of tolerance to THC hypolocomotor effect. In contrast, the hippocampus and prefrontal cortex showed CB1 receptor adaptations regardless of the genetic or pharmacological inhibition of the ERK pathway, suggesting regional variability in the cellular events underlying the altered CB1 receptor function. These findings suggest that at least in the caudate putamen and cerebellum, the Ras/ERK pathway is essential for triggering the alteration in CB1 receptor function responsible for tolerance to THC-induced hypomotility. 相似文献
104.
Background
There is a lack of recent studies examining recording of influenza-like illness (ILI) in primary care in the UK over time and according to population characteristics. Our aim was to determine time trends and socio-demographic patterns of ILI recorded consultations in primary care.Methods
We used The Health Improvement Network (THIN) UK primary care database and extracted data on all ILI consultations between 1995 and 2013. We estimated ILI recorded consultation rates per 100,000 person-weeks (pw) by age, gender, deprivation and winter season. Negative binomial regression models were used to examine time trends and the effect of socio-demographic characteristics. Trends in ILI recorded consultations were compared to trends in consultations with less specific symptoms (cough or fever) recorded.Results
The study involved 7,682,908 individuals in 542 general practices. The ILI consultation rate decreased from 32.5/100,000 pw (95% confidence interval (CI) 32.1, 32.9) in 1995–98 to 15.5/100,000 pw (95% CI 15.4, 15.7) by 2010–13. The decrease occurred prior to 2002/3, and rates have remained largely stable since then. Declines were evident in all age groups. In comparison, cough or fever consultation rates increased from 169.4/100,000 pw (95% CI 168.6, 170.3) in 1995–98 to 237.7/100,000 pw (95% CI 237.2, 238.2) in 2010–13. ILI consultation rates were highest among individuals aged 15–44 years, higher in women than men, and in individuals from deprived areas.Conclusion
There is substantial variation in ILI recorded consultations over time and by population socio-demographic characteristics, most likely reflecting changing recording behaviour by GPs. These results highlight the difficulties in using coded information from electronic primary care records to measure the severity of influenza epidemics across time and assess the relative burden of ILI in different population subgroups. 相似文献105.
Chung-Jung Lin Greta S. P. Mok Mang-Fen Tsai Wei-Ta Tsai Bang-Hung Yang Chun-Yuan Tu Tung-Hsin Wu 《PloS one》2015,10(6)
Introduction
The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database.Materials and Methods
Taiwan’s Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed.Results
CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C.Conclusion
CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices. 相似文献106.
Background
Representing approximately 0.5% of the population, transgender (trans) persons in Canada depend on family physicians for both general and transition-related care. However, physicians receive little to no training on this patient population, and trans patients are often profoundly uncomfortable and may avoid health care. This study examined factors associated with patient discomfort discussing trans health issues with a family physician in Ontario, Canada.Methods
433 trans people age 16 and over were surveyed using respondent-driven sampling for the Trans PULSE Project; 356 had a family physician. Weighted logistic regression models were fit to produce prevalence risk ratios (PRRs) via average marginal predictions, for transmasculine (n = 184) and transfeminine (n = 172) trans persons.Results
Among the 83.1% (95% CI = 77.4, 88.9) of trans Ontarians who had a family physician, approximately half reported discomfort discussing trans health issues. 37.2% of transmasculine and 38.1% of transfeminine persons reported at least one trans-specific negative experience. In unadjusted analysis, sociodemographics did not predict discomfort, but those who planned to medically transition sex, but had not begun, were more likely to report discomfort (transmasculine: PRR = 2.62 (95% CI = 1.44, 4.77); transfeminine: PRR = 1.85 (95% CI = 1.08, 3.15)). Adjusted for other factors, greater perceived physician knowledge about trans issues was associated with reduced likelihood of discomfort, and previous trans-specific negative experiences with a family physician with increased discomfort. Transfeminine persons who reported three or more types of negative experiences were 2.26 times as likely, and transmasculine persons 1.61 times as likely, to report discomfort. In adjusted analyses, sociodemographic associations differed by gender, with being previously married or having higher education associated with increased risk of discomfort among transfeminine persons, but decreased risk among transmasculine persons.Conclusions
Within this transgender population, discomfort in discussing trans health issues with a family physician was common, presenting a barrier to accessing primary care despite having a regular family physician and “universal” health insurance. 相似文献107.
Greta J. Frankham Kathrine A. Handasyde Melinda Norton Andrew Murray Mark D. B. Eldridge 《Conservation Genetics》2014,15(3):547-560
Fine-scale genetic structure was investigated in three regional populations of the long-nosed potoroo (Potorous tridactylus) a threatened endemic marsupial. Two populations were from the Australian mainland and one from an island. Populations were sub-sampled at two sites, 6–8 km apart, connected by suitable habitat for dispersal. Factors influencing fine-scale structure were investigated by genotyping 157 individuals at 10 microsatellite loci and sequencing a ~621 bp region of the mtDNA control region. Results indicated that P. tridactylus populations exhibit significant intra-population structure, with significant F ST and Φ ST values recorded between subpopulations. This structure appeared mediated by small neighbourhood size, female philopatry and limited dispersal over 6–8 km, predominantly by males. Results highlighted several important features of P. tridactylus populations that have implications for conservation. Firstly, the small neighbourhood size suggests any investigations of intra-population structure should be conducted on a finer scale (e.g. 25–50 m) than many current monitoring programs. Secondly, the island populations were genetically depauperate, which may reflect processes occurring in many isolated ‘mainland island’ populations. Thirdly, the lower gene flow identified between populations separated by anthropogenically modified habitat suggests P. tridactylus is sensitive to changes in habitat configuration. 相似文献
108.
Savic D Distler MG Sokoloff G Shanahan NA Dulawa SC Palmer AA Nobrega MA 《PloS one》2011,6(10):e26897
The comorbidity of type 2 diabetes (T2D) with several psychiatric diseases is well established. While environmental factors may partially account for these co-occurrences, common genetic susceptibilities could also be implicated in the confluence of these diseases. In support of shared genetic burdens, TCF7L2, the strongest genetic determinant for T2D risk in the human population, has been recently implicated in schizophrenia (SCZ) risk, suggesting that this may be one of many loci that pleiotropically influence both diseases. To investigate whether Tcf7l2 is involved in behavioral phenotypes in addition to its roles in glucose metabolism, we conducted several behavioral tests in mice with null alleles of Tcf7l2 or overexpressing Tcf7l2. We identified a role for Tcf7l2 in anxiety-like behavior and a dose-dependent effect of Tcf7l2 alleles on fear learning. None of the mutant mice showed differences in prepulse inhibition (PPI), which is a well-established endophenotype for SCZ. These results show that Tcf7l2 alters behavior in mice. Importantly, these differences are observed prior to the onset of detectable glucose metabolism abnormalities. Whether these differences are related to human anxiety-disorders or schizophrenia remains to be determined. These animal models have the potential to elucidate the molecular basis of psychiatric comorbidities in diabetes and should therefore be studied further. 相似文献
109.
Kaniewski D Van Campo E Van Lerberghe K Boiy T Vansteenhuyse K Jans G Nys K Weiss H Morhange C Otto T Bretschneider J 《PloS one》2011,6(6):e20232
The 13(th) century BC witnessed the zenith of the Aegean and Eastern Mediterranean civilizations which declined at the end of the Bronze Age, ~3200 years ago. Weakening of this ancient flourishing Mediterranean world shifted the political and economic centres of gravity away from the Levant towards Classical Greece and Rome, and led, in the long term, to the emergence of the modern western civilizations. Textual evidence from cuneiform tablets and Egyptian reliefs from the New Kingdom relate that seafaring tribes, the Sea Peoples, were the final catalyst that put the fall of cities and states in motion. However, the lack of a stratified radiocarbon-based archaeology for the Sea People event has led to a floating historical chronology derived from a variety of sources spanning dispersed areas. Here, we report a stratified radiocarbon-based archaeology with anchor points in ancient epigraphic-literary sources, Hittite-Levantine-Egyptian kings and astronomical observations to precisely date the Sea People event. By confronting historical and science-based archaeology, we establish an absolute age range of 1192-1190 BC for terminal destructions and cultural collapse in the northern Levant. This radiocarbon-based archaeology has far-reaching implications for the wider Mediterranean, where an elaborate network of international relations and commercial activities are intertwined with the history of civilizations. 相似文献
110.
Aeby GS Williams GJ Franklin EC Haapkyla J Harvell CD Neale S Page CA Raymundo L Vargas-Ángel B Willis BL Work TM Davy SK 《PloS one》2011,6(2):e16887
Growth anomalies (GAs) are common, tumor-like diseases that can cause significant morbidity and decreased fecundity in the major Indo-Pacific reef-building coral genera, Acropora and Porites. GAs are unusually tractable for testing hypotheses about drivers of coral disease because of their pan-Pacific distributions, relatively high occurrence, and unambiguous ease of identification. We modeled multiple disease-environment associations that may underlie the prevalence of Acropora growth anomalies (AGA) (n = 304 surveys) and Porites growth anomalies (PGA) (n = 602 surveys) from across the Indo-Pacific. Nine predictor variables were modeled, including coral host abundance, human population size, and sea surface temperature and ultra-violet radiation anomalies. Prevalence of both AGAs and PGAs were strongly host density-dependent. PGAs additionally showed strong positive associations with human population size. Although this association has been widely posited, this is one of the first broad-scale studies unambiguously linking a coral disease with human population size. These results emphasize that individual coral diseases can show relatively distinct patterns of association with environmental predictors, even in similar diseases (growth anomalies) found on different host genera (Acropora vs. Porites). As human densities and environmental degradation increase globally, the prevalence of coral diseases like PGAs could increase accordingly, halted only perhaps by declines in host density below thresholds required for disease establishment. 相似文献