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911.
Rodrigo Scheihing Leyla Cardenas Roberto F. Nespolo Paola Krall Katherina Walz Shiro Kohshima Pedro Labarca 《Hydrobiologia》2010,637(1):45-52
In small metazoan invertebrates classical taxonomic analyses can be ambiguous due to the limited number of morphological characters
available. This difficulty can yield incorrect estimates of species richness or taxa distribution. The Boeckella genus has been described as the dominant taxon of zooplankton assemblages in the Andean biogeographical region. In this genus,
taxonomic classification and delimitation of boundaries between species has long been problematic and controversial. Among
South American centropagids Boeckella gracilipes has been regarded as one of the most broadly distributed species, its presence having been reported from Ecuador to Tierra
del Fuego. However, in the high Andean plateau some centropagid populations identified as Boeckella gracilipes have also been considered as B. gracilipes titicacae or even identified as a different species, namely Boeckella titicacae. In an attempt to resolve the taxonomic status of the Centropagidae family from the high Andean plateau, we combined traditional
and multivariate morphological analyses (integral approach) with the molecular phylogenetic approach. The results obtained
allow us to conclude that centropagids collected from the high Andean plateau actually represent a different species, B. titicacae, not B. gracilipes. The phylogenetic reconstruction of the South American Centropagidae family indicated that B. gracilipes represents a sister taxon to B. titicacae. The present study stresses the usefulness of integrating alfa-taxonomy with morphometric and molecular approaches in order
to resolve species boundaries, to determine geographical distributions and to investigate evolutionary processes. 相似文献
912.
María Fernández-Raga Clemente Tomás Roberto Fraile 《International journal of biometeorology》2010,54(4):379-392
This study was carried out in the region of Castile and Leon, Spain, from 1980 to 1998 and analyzes the relationship between
the number of monthly deaths caused by cardiovascular, respiratory and digestive diseases and three meteorological variables:
temperature, pressure and humidity. One of the innovations in this study is the application of principal component analysis
in a way that differs from its usual application: one single series representing the whole region was constructed for each
meteorological variable from the series of eight weather stations. Annual and seasonal mortality trends were also studied.
Cardiovascular diseases are the leading cause of death in Castile and Leon. The mortality related to cardiovascular, respiratory
and digestive systems shows a statistically significant rising trend across the study period (an annual increase of 6, 16
and 4‰, respectively). The pressure at which mortality is lowest is approximately the same for all causes of death (about
915 hPa), but temperature values vary greatly (16.8–19.7°C for the mean, 10.9–18.1°C for the minimum, and 24.1–27.2°C for
the maximum temperature). The most comfortable temperatures for patients with cardiovascular diseases (16.8°C) are apparently
lower than those for patients with respiratory diseases (18.1°C), which are, in turn, lower than in the case of diseases of
the digestive system (19.7°C). Finally, the optimal humidity for patients with respiratory diseases is the lowest (24%) among
the diseases, and the highest (51%) corresponds to diseases of the digestive system, while the optimal relative humidity for
the cardiovascular system is 45%. 相似文献
913.
Nicola Ferrari Roberto Rosà Kathreen E. Ruckstuhl 《International journal for parasitology》2010,40(11):1285-1293
We investigated whether sexual segregation might affect parasite transmission and host dynamics, hypothesising that if males are the more heavily infected sex and more responsible for the transmission of parasite infections, female avoidance of males and the space they occupy could reduce infection rates. A mathematical model, simulating the interaction between abomasal parasites and a hypothetical alpine ibex (Capraibex) host population composed of its two sexes, was developed to predict the effect of different degrees of sexual segregation on parasite intensity and on host abundance. The results showed that when females tended to be segregated from males, and males were distributed randomly across space, the impact of parasites was the lowest, resulting in the highest host abundance, with each sex having the lowest parasite intensity. The predicted condition that minimises the impact of parasites in our model was the one closest to that observed in nature where females actively seek out the more segregated sites while males are less selective in their ranging behaviour. The overlapping of field observation with the predicted optimal strategy lends support to our idea that there might be a connection between parasite transmission and sexual segregation. Our simulations provide the biological boundaries of host-parasite interaction needed to determine a parasite-mediated effect on sexual segregation and a formalised null hypothesis against which to test future field experiments. 相似文献
914.
Paola Cescutti Michela Foschiatti Linda Furlanis Cristina Lagatolla Roberto Rizzo 《Carbohydrate research》2010,345(10):1455-1460
The repeating unit of cepacian, the exopolysaccharide produced by the majority of the microorganisms belonging to the Burkholderia cepacia complex, was isolated from inner bacterial membranes and investigated by mass spectrometry, with and without prior derivatisation. Interpretation of the mass spectra led to the determination of the biological repeating unit primary structure, thus disclosing the nature of the oligosaccharide produced in vivo. Moreover, mass spectra recorded on the native sample revealed that acetyl substitution was very variable, producing a mixture of repeating units containing zero to four acyl groups. At the same time, finding acetylated oligosaccharides showed that binding of these substituents occurred in the cellular periplasmic space, before the polymerisation process took place. In the chromatographic peak containing the repeating unit, oligosaccharides shorter than the repeating unit co-eluted. Mass spectrometric analysis showed that they were biosynthetic intermediates of the repeating unit and further investigation revealed the biosynthetic sequence of cepacian building block. 相似文献
915.
Tania Massignan Richard S. Stewart Emiliano Biasini Isaac H. Solomon Valentina Bonetto Roberto Chiesa David A. Harris 《The Journal of biological chemistry》2010,285(10):7752-7765
In prion diseases, the infectious isoform of the prion protein (PrPSc) may subvert a normal, physiological activity of the cellular isoform (PrPC). A deletion mutant of the prion protein (Δ105–125) that produces a neonatal lethal phenotype when expressed in transgenic mice provides a window into the normal function of PrPC and how it can be corrupted to produce neurotoxic effects. We report here the surprising and unexpected observation that cells expressing Δ105–125 PrP and related mutants are hypersensitive to the toxic effects of two classes of antibiotics (aminoglycosides and bleomycin analogues) that are commonly used for selection of stably transfected cell lines. This unusual phenomenon mimics several essential features of Δ105–125 PrP toxicity seen in transgenic mice, including rescue by co-expression of wild type PrP. Cells expressing Δ105–125 PrP are susceptible to drug toxicity within minutes, suggesting that the mutant protein enhances cellular accumulation of these cationic compounds. Our results establish a screenable cellular phenotype for the activity of neurotoxic forms of PrP, and they suggest possible mechanisms by which these molecules could produce their pathological effects in vivo. 相似文献
916.
Pillai JB Gupta M Rajamohan SB Lang R Raman J Gupta MP 《American journal of physiology. Heart and circulatory physiology》2006,291(4):H1545-H1553
Poly(ADP-ribose) polymerase-1 (PARP), a chromatin-bound enzyme, is activated by cell oxidative stress. Because oxidative stress is also considered a main component of angiotensin II-mediated cell signaling, it was postulated that PARP could be a downstream target of angiotensin II-induced signaling leading to cardiac hypertrophy. To determine a role of PARP in angiotensin II-induced hypertrophy, we infused angiotensin II into wild-type (PARP(+/+)) and PARP-deficient mice. Angiotensin II infusion significantly increased heart weight-to-tibia length ratio, myocyte cross-sectional area, and interstitial fibrosis in PARP(+/+) but not in PARP(-/-) mice. To confirm these results, we analyzed the effect of angiotensin II in primary cultures of cardiomyocytes. When compared with PARP(-/-) cardiomyocytes, angiotensin II (1 microM) treatment significantly increased protein synthesis in PARP(+/+) myocytes, as measured by (3)H-leucine incorporation into total cell protein. Angiotensin II-mediated hypertrophy of myocytes was accompanied with increased poly-ADP-ribosylation of nuclear proteins and depletion of cellular NAD content. When cells were treated with cell death-inducing doses of angiotensin II (10-20 microM), robust myocyte cell death was observed in PARP(+/+) but not in PARP(-/-) myocytes. This type of cell death was blocked by repletion of cellular NAD levels as well as by activation of the longevity factor Sir2alpha deacetylase, indicating that PARP induction and subsequent depletion of NAD levels are the sequence of events causing angiotensin II-mediated cardiomyocyte cell death. In conclusion, these results demonstrate that PARP is a nuclear integrator of angiotensin II-mediated cell signaling contributing to cardiac hypertrophy and suggest that this could be a novel therapeutic target for the management of heart failure. 相似文献
917.
Li Q Guo Y Tan W Stein AB Dawn B Wu WJ Zhu X Lu X Xu X Siddiqui T Tiwari S Bolli R 《American journal of physiology. Heart and circulatory physiology》2006,290(2):H584-H589
Previous studies have shown that gene therapy with inducible nitric oxide synthase (iNOS) protects against myocardial infarction at 3 days after gene transfer. However, the long-term effects of iNOS gene therapy on myocardial ischemic injury and cardiac function are unknown. To address this issue, we used a recombinant adenovirus 5 (Ad5) vector (Av3) with deletions of the E1, E2a, and E3 regions, which enables long-lasting recombinant gene expression for at least 2 mo due to lack of inflammation. Mice received intramyocardial injections in the left ventricular (LV) anterior wall of Av3/LacZ (LacZ group) or Av3/iNOS (iNOS group); 1 or 2 mo later, they were subjected to myocardial infarction (30-min coronary occlusion followed by 4 h of reperfusion). Cardiac iNOS gene expression was confirmed by immunoblotting and activity assays at 1 and 2 mo after gene transfer. In the iNOS group, infarct size (percentage of risk region) was significantly reduced (P < 0.05) both at 1 mo (24.2 +/- 3.4%, n = 6, vs. 48.0 +/- 3.6%, n = 8, in the LacZ group) and at 2 mo (23.4 +/- 3.1%, n = 8, vs. 36.6 +/- 2.4%, n = 7). The infarct-sparing effects of iNOS gene therapy were as powerful as those observed 24 h after ischemic preconditioning (23.1 +/- 3.4%, n = 10). iNOS gene transfer had no effect on LV function or dimensions up to 8 wk later (echocardiography). These data demonstrate that iNOS gene therapy mediated by the Av3 vector affords long-term (2 mo) cardioprotection without inflammation or adverse functional consequences, a finding that provides a rationale for further preclinical testing of this therapy. 相似文献
918.
Roberto R. Licandeo Claudio A. Barrientos María Teresa González 《Environmental Biology of Fishes》2006,77(1):51-61
The róbalo, Eleginops maclovinus, a protandrous hermaphrodite species, is an important component of the ichthyofauna in the coastal areas and estuaries of southern Chile. However, there are many aspects about its life history that are unknown. Three hundred and eighty-three specimens of E. maclovinus (19–79 cm total length, TL) were collected between November 2002 and December 2003 from central-southern Chile. Marginal increment analysis from sagittal otoliths showed a single annual minimum in March, demonstrating that a single growth ring is formed each year. The growth of E. maclovinus was described by the von Bertalanffy growth model by following parameters: L
∞
= 105.4 cm TL, K = 0.08 per year, and t
0
= −1.03 years. E. maclovinus can live for 10 years. The length and age at which the 50% of the males in the population transformed into females was estimated at ~36 cm TL and ~5-years old. A total of 27 prey items were identified. The most important prey items were the crustaceans Hemigrapsus crenulatus and Emerita analoga associated with estuarial and marine habitats respectively. Ontogenetic changes in the diet were related to the spatial distributional pattern of males (1–4 years old, in the estuary) and females (5–8 years old, in the sea). Also, diet changes are associated with the type of available prey in each habitat occupied, indicating a generalized opportunist strategy. 相似文献
919.
Dhillon H Zigman JM Ye C Lee CE McGovern RA Tang V Kenny CD Christiansen LM White RD Edelstein EA Coppari R Balthasar N Cowley MA Chua S Elmquist JK Lowell BB 《Neuron》2006,49(2):191-203
Leptin, an adipocyte-derived hormone, acts directly on the brain to control food intake and energy expenditure. An important question is the identity of first-order neurons initiating leptin's anti-obesity effects. A widely held view is that most, if not all, of leptin's effects are mediated by neurons located in the arcuate nucleus of the hypothalamus. However, leptin receptors (LEPRs) are expressed in other sites as well, including the ventromedial hypothalamus (VMH). The possible role of leptin acting in "nonarcuate" sites has largely been ignored. In the present study, we show that leptin depolarizes and increases the firing rate of steroidogenic factor-1 (SF1)-positive neurons in the VMH. We also show, by generating mice that lack LEPRs on SF1-positive neurons, that leptin action at this site plays an important role in reducing body weight and, of note, in resisting diet-induced obesity. These results reveal a critical role for leptin action on VMH neurons. 相似文献
920.