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991.
The kidney is an extremely complex organ with broad ranging functions in the body, including but not restricted to waste excretion,
ion and water balance, maintenance of blood pressure, glucose homeostasis, generation of erythropoietin and activation of
vitamin D. With diabetes, many of these integral processes are interrupted via a combination of haemodynamic and metabolic
changes including increases in the accumulation of proteins modified by advanced glycation, known as advanced glycation end
products (AGEs). Indeed, hyperglycaemia and the redox imbalances seen with diabetes are each independent accelerants for the
production of AGEs, which synergistically combine in this disorder. In addition, as kidney function declines, characterised
by a loss of glomerular filtration, the excretion of AGEs is decreased, possibly exacerbating renal injury by further elevating
the body’s tissue and circulating AGE pool. Therefore, it has become apparent that decreasing the accumulation of AGEs or
interrupting their downstream effects on the kidney, are desirable therapeutic targets for the treatment of diabetic renal
disease. 相似文献
992.
993.
Maggio CD Jennings SR Robichaux JL Stapor PC Hyman JM 《Bulletin of mathematical biology》2012,74(1):143-158
We extend and analyze the Wang and Politi modified Hai–Murphy model of smooth muscle cell contractions to capture uterine
muscle cell response to variations in intracellular calcium concentrations. This model is used to estimate values of unknown
parameters in uterine smooth muscle cell cross-bridging. Uterine motility is responsible for carrying out important processes
throughout all phases of the nonpregnant female reproductive cycle, including sperm transport, menstruation, and embryo implantation.
The modified Hai–Murphy partial differential equation model accounts for the displacement of myosin cross-bridge heads relative
to their binding sites. This model was originally developed for the study of airway contractions; we now extended it for use
in modeling nonisometric uterine contractions. Our extended model incorporates cross-bridge position and contractile velocity
into the original model, resulting in more accurate modeling of the initial stages of contraction and modeling nonisometric
contractions. Numerical simulations show that the contraction rate in our extended model is faster than the original Hai–Murphy
model. These simulations provide quantitative estimates for the increased level of responsiveness of our extended model to
intracellular calcium concentrations. The extended model and new parameter estimates for the cross-bridging can be coupled
with uterine flow models to advance our understanding of embryonic motility and intrauterine flow. 相似文献
994.
Leif Egil Loe Christophe Bonenfant Erling L. Meisingset Atle Mysterud 《European Journal of Wildlife Research》2012,58(1):195-203
Species distribution models (SDMs) are popular in conservation and management of a wide array of taxa. Often parameterized
with coarse GIS-based environmental maps, they perform well in macro-ecological settings but it is debated if the models can
predict distribution within broadly suitable “known” habitats of interest to local managers. We parameterized SDMs with GIS-derived
environmental variables and location data from 82 GPS-collared female red deer (Cervus elaphus) from two study areas in Norway. Candidate GLM models were fitted to address the effect of spatial scale (landscape vs. home
range), sample size, and transferability between study areas, with respect to predictability (AUC) and explained variance
(Generalized R
2 and deviance). The landscape level SDM captured variation in deer distribution well and performed best on all diagnostic
measures of model quality, caused mainly by a trivial effect of avoidance of non-habitat (barren mountains). The home range
level SDMs were far less predictable and explained comparatively little variation in space use. Landscape scale models stabilized
at the low sample size of 5–10 individuals and were highly transferrable between study areas implying a low degree of individual
variation in habitat selection at this scale. It is important to have realistic expectations of SDMs derived from digital
elevation models and coarse habitat maps. They do perform well in highlighting potential habitat on a landscape scale, but
often miss nuances necessary to predict more fine-scaled distribution of wildlife populations. Currently, there seems to be
a trade-off between model quality and usefulness in local management. 相似文献
995.
Chinsriwongkul A Chareanputtakhun P Ngawhirunpat T Rojanarata T Sila-on W Ruktanonchai U Opanasopit P 《AAPS PharmSciTech》2012,13(1):150-158
The purpose of this research was to formulate nanostructured lipid carriers (NLC) for the parenteral delivery of an anticancer
drug, all-trans retinoic acid (ATRA). The ATRA was incorporated into NLC by the de novo emulsification method. The effect of the formulation
factor, i.e., type and oil ratio, initial ATRA concentration on physicochemical properties was determined. The anticancer
efficacy of ATRA-loaded NLC on HL-60 and HepG2 cells was also studied. NLC was formulated using a blend of solid lipids (cetyl
palmitate) and liquid lipids (soybean oil (S), medium-chain triglyceride (M), S/oleic acid (O; 3:1) and M/O (3:1)) at a weight
ratio of 1:1. ATRA-loaded NLC had an average size of less than 200 nm (141.80 to 172.95 nm) with a narrow PDI and negative
zeta potential that was within an acceptable range for intravenous injection. The results indicated that oleic acid enhanced
the ATRA-loading capacity of NLC. In vitro ATRA release was only approximately 4.06% to 4.34% for 48 h, and no significant difference in ATRA release rate from all
NLC formulations in accordance with the composition of the oil phase. Moreover, no burst release of the drug was observed,
indicating that NLC could prolong the release of ATRA. The initial drug concentration affected the photodegradation rate but
did not affect the release rate. All ATRA-loaded NLC formulations exhibited the photoprotective property. The cytotoxicity
results showed that all ATRA-loaded NLC had higher cytotoxicity than the free drug and HL-60 cells were more sensitive to
ATRA than HepG2 cells. 相似文献
996.
Gath J Habenstein B Bousset L Melki R Meier BH Böckmann A 《Biomolecular NMR assignments》2012,6(1):51-55
Parkinson’s disease is amongst the most frequent and most devastating neurodegenerative diseases. It is tightly associated
with the assembly of proteins into high-molecular weight protein species, which propagate between neurons in the central nervous
system. The principal protein involved in this process is α-synuclein which is a structural component of the Lewy bodies observed
in diseased brain. We here present the solid-state NMR sequential assignments of a new fibrillar form of this protein, the
first one with a well-ordered and rigid N-terminal part. 相似文献
997.
Christina A. Olson Karen H. Beard David N. Koons William C. Pitt 《Biological invasions》2012,14(4):889-900
Two nonnative Caribbean frogs, the Puerto Rican coqui and the Cuban greenhouse frog, recently invaded Hawaii. Because of its
louder breeding call, management efforts have focused on the coqui, while little has been done to address the more cryptic
greenhouse frog, even though it may be as widespread and have similar ecological impacts. The goal of this research was to
determine the distribution and detection probability of both species on the island of Hawaii. We conducted a breeding call
presence/absence survey at 446 sites every 2 km along major road networks. We re-surveyed 125 sites twice to determine detection
and occupancy probabilities. Greenhouse frog detection probabilities (0.24, 0.29, 0.48, for each of the three visits, respectively)
were lower than coqui detection probabilities (0.58, 0.73, 0.50, respectively) and increased with visits while those of the
coqui did not. Greenhouse frog detection probabilities were lower in the presence of coquis for the first two surveys (0.12,
0.14) than in sites with greenhouse frogs alone (0.41), while greenhouse frogs had no effect on the detection of coquis. Site
occupancy estimates for the greenhouse and coqui frog were 0.35 and 0.31, respectively, suggesting the species are similarly
widespread. Results suggest multiple visits to sites are required to detect the greenhouse frog. Furthermore, results suggest
that accounting for detectability is essential when determining the extent of invasion of cryptic species. 相似文献
998.
Rb1 and Rg1 are the major ginsenosides in protopanaxadiol and protopanaxatriol. Their content in ginsenosides was 23.8 and 17.6%, respectively.
A total of 22 isolates of β-glucosidase producing microorganisms were isolated from the soil of a ginseng field using Esculin-R2A
agar. Among these isolates, the strain GH21 showed the strongest activities to convert ginsenoside Rb1 and Rg1 to minor ginsenosides compound-K and F1, respectively. Ginsenosides Rb1 and Rg1 bioconversion rates were 74.2 and 89.3%, respectively. Meanwhile, the results demonstrated that the ginsenoside Rg1 could change the biotransformation pathway of ginsenoside Rb1 by inhibiting the formation of the intermediate metabolite gypenoside-XVII. GH21 was identified as a Cladosporium cladosporioides species based on the internal transcribed spacers (ITS) ITS1-5.8S-ITS2 rRNA gene sequences constructed phylogenetic trees. 相似文献
999.
Cho SY Jeong EM Lee JH Kim HJ Lim J Kim CW Shin DM Jeon JH Choi K Kim IG 《Molecules and cells》2012,33(3):235-241
The activation of transglutaminase 2 (TG2), an enzyme that catalyzes post-translational modifications of proteins, has been
implicated in apoptosis, cell adhesion and inflammatory responses. We previously reported that intracellular TG2 is activated
under oxidative stress conditions, such as ultraviolet irradiation, ischemia-reperfusion, and hypoxia. In this study, we examined
the effect of genotoxic stress on the intracellular activity of TG2 using doxorubicin which generates reactive oxygen species
that lead to double-strand breakage of DNA. We demonstrated that doxorubicin elicits the persistent activation of TG2. Doxorubicin-induced
TG2 activity was suppressed by treatment with caffeine at the early phase, N-acetylcysteine at the mid-phase, and EGTA at
the late phase. However, treatment with a blocking antibody against TGFβ or toll-like receptor 2 showed no effect on TG2 activity,
indicating that at least three different signaling pathways may be involved in the process of TG2 activation. In addition,
using MEF cells defective for TG2 and cells overexpressing an activesite mutant of TG2, we revealed that doxorubicin-induced
cell death is inversely correlated with TG2 activity. Our findings indicate that the persistent activation of TG2 by doxorubicin
contributes to cell survival, suggesting that the mechanism-based inhibition of TG2 may be a novel strategy to prevent drug-resistance
in doxorubicin treatment. 相似文献
1000.
Autophagy is an evolutionary conserved process of bulk degradation and nutrient sequestration that occurs in all eukaryotic
cells. Yet, in recent years, autophagy has also been shown to play a role in the specific degradation of individual proteins
or protein aggregates as well as of damaged organelles. The process was initially discovered in yeast and has also been very
well studied in mammals and, to a lesser extent, in plants. In this review, we summarize what is known regarding the various
functions of autopahgy in plants but also attempt to address some specific issues concerning plant autophagy, such as the
insufficient knowledge regarding autophagy in various plant species other than Arabidopsis, the fact that some genes belonging to the core autophagy machinery in various organisms are still missing in plants, the
existence of autophagy multigene families in plants and the possible operation of selective autophagy in plants, a study that
is still in its infancy. In addition, we point to plant-specific autophagy processes, such as the participation of autophagy
during development and germination of the seed, a unique plant organ. Throughout this review, we demonstrate that the use
of innovative bioinformatic resources, together with recent biological discoveries (such as the ATG8-interacting motif), should
pave the way to a more comprehensive understanding of the multiple functions of plant autophagy. 相似文献