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961.
The present investigation was undertaken with the objective of developing a solid formulation containing nitrendipine nanocrystals
for oral delivery. Nitrendipine nanocrystals were prepared using a tandem precipitation–homogenization process. Then, spray
drying, a cost-effective method very popular in industrial situations, was employed to convert the nanocrystals into a solid
form. The parameters of the preparation process were investigated and optimized. The optimal process was as follows: firstly,
nitrendipine/acetone solution (100 mg/ml) was added to a polyvinyl alcohol solution (1 mg/ml) at 10°C, then the pre-suspension
was homogenized for 20 cycles at 1,000 bar. Both differential scanning calorimetry and X-ray diffraction analysis indicated
that nitrendipine was present in crystalline form. The in vitro dissolution rate of the nanocrystals was significantly increased compared with the physical mixture and commercial tablet.
The in vivo testing demonstrated that the C
max of the nanocrystals was approximately 15-fold and 10-fold greater than that of physical mixture and commercial tablet, respectively.
In addition, the AUC0→24 of the nanocrystals was approximately 41-fold and 10-fold greater than that of physical mixture and commercial tablet, respectively. 相似文献
962.
The soil/air partition coefficients (K SA ) for hexachlorobenzene (HCB) in oil-contaminated (crude oil and diesel) rice paddy field soils were measured in a solid fugacity meter at different oil concentrations over the temperature range of 5 to 30°C at 100% relative humidity. The results showed that values of K SA increased with a decrease of temperature. As for oil content, there is a critical separate phase concentration (CSPC) above which K SA increased with increasing of oil content. When oil content is above CSPC, oil plays a role as a separate phase that enhances the sorption capacity of the soil. At a given temperature (20°C) values of CSPC depended on the natural organic matter (NOM) contents of the soil, while for a given oil concentration they depended on the temperature. The normalized oil/air partition coefficients ) for HCB deduced from K SA for oils and experimentally determined with crude oil/quartz sand system were similar and 0.7–7 times higher than the normalized organic/air partition coefficient ), which implied that oil was a super sorbent. The enthalpies (ΔHSA) for crude oil and diesel were 64.9 and 55.7 kJ mol?1, respectively. 相似文献
963.
Li T Wang J Li Y Zhang L Zheng L Li Z Yang Z Luo Q 《Journal of molecular modeling》2011,17(7):1661-1668
In the structural-based mutagenesis of Mucor pusillus pepsin (MPP), understanding how κ-casein interacts with MPP is a great challenge for us to explore. Chymosin-sensitive peptide
is the key domain of κ-casein that regulates milk clotting through the specific proteolytic cleavage of its peptide bond (Phe105-Met106) by MPP to produce insoluble para-κ-casein. Here, we built the model of this large peptide using molecular modeling technique.
Docking study showed that MPP can accommodate the designed model with a favorable binding energy and the docked complex has
proven to locally resemble the inhibitor-chymosin complex. The catalytic mechanism for the peptide model binding with MPP
was explored in terms of substrate-enzyme interaction and property of contacting surface. Some critical amino acid residues
in the substrate binding cleft have been identified as an important guide for further site-directed mutagenesis. Glu13 and
Leu11 in the S3 region of MPP, predicted as the special mutation sites, were confirmed to retain clotting activity and decrease
the proteolytic activity. These novel mutants may provide a promising application for improving cheese flavor. 相似文献
964.
965.
Seung-Oe Lim Hyeon Seop Kim Xiaoyuan Quan Sun-Min Ahn Hongtae Kim David Hsieh Je Kyung Seong Guhung Jung 《BMC biology》2011,9(1):1-12
Background
Infection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of the rare examples where coevolution has been documented, in order to resolve the steps of the infection and analyse the factors that influence each of them.Results
Using the transparent Daphnia hosts and fluorescently-labelled spores of the bacterium P. ramosa, we identified a sequence of infection steps: encounter between parasite and host; activation of parasite dormant spores; attachment of spores to the host; and parasite proliferation inside the host. The chances of encounter had been shown to depend on host genotype and environment. We tested the role of genetic and environmental factors in the newly described activation and attachment steps. Hosts of different genotypes, gender and species were all able to activate endospores of all parasite clones tested in different environments; suggesting that the activation cue is phylogenetically conserved. We next established that parasite attachment occurs onto the host oesophagus independently of host species, gender and environmental conditions. In contrast to spore activation, attachment depended strongly on the combination of host and parasite genotypes.Conclusions
Our results show that different steps are influenced by different factors. Host-type-independent spore activation suggests that this step can be ruled out as a major factor in Daphnia - Pasteuria coevolution. On the other hand, we show that the attachment step is crucial for the pronounced genetic specificities of this system. We suggest that this one step can explain host population structure and could be a key force behind coevolutionary cycles. We discuss how different steps can explain different aspects of the coevolutionary dynamics of the system: the properties of the attachment step, explaining the rapid evolution of infectivity and the properties of later parasite proliferation explaining the evolution of virulence. Our study underlines the importance of resolving the infection process in order to better understand host-parasite interactions. 相似文献966.
ABSTRACT: INTRODUCTION: The incidence of lipoma in the Eustachian tube is very rare, and to the best of our knowledge, has not been reported in the literature. Tumors that form in the cartilaginous portion of the Eustachian tube can be successfully removed by an endoscopic approach. CASE PRESENTATION: We report an incidentally-detected lipoma of the Eustachian tube in a 34-year-old Asian woman with a six-year history of persistent otitis media in her right ear. Our patient underwent surgery five years ago for the possibility of a choanal polyp, but her ear symptoms continued to be problematic following the surgery. Our patient was examined at our hospital, and computed tomography revealed a well-defined, hypodense, non-enhancing lesion involving the right Eustachian tube, measuring 1.6x2.4cm. The mass was excised using an endoscopic approach, and was found to originate from the cartilaginous portion of the Eustachian tube. The tumor was sent for histopathologic evaluation. The postoperative course went smoothly, and our patient recovered during follow-up over the next five months. CONCLUSION: Lipoma of the Eustachian tube is very rare compared with other tumors. Improved radiologic modalities aid the diagnosis of this benign tumor. Endoscopic removal of the tumor is possible and has helped in early recovery. 相似文献
967.
Quan T Qin Z Robichaud P Voorhees JJ Fisher GJ 《Journal of cell communication and signaling》2011,5(3):201-207
Dermal connective tissue collagen is the major structural protein in skin. Fibroblasts within the dermis are largely responsible
for collagen production and turnover. We have previously reported that dermal fibroblasts, in aged human skin in vivo, express
elevated levels of CCN1, and that CCN1 negatively regulates collagen homeostasis by suppressing collagen synthesis and increasing
collagen degradation (Quan et al. Am J Pathol 169:482–90, 2006, J Invest Dermatol 130:1697–706, 2010). In further investigations of CCN1 actions, we find that CCN1 alters collagen homeostasis by promoting expression of specific
secreted proteins, which include matrix metalloproteinases and proinflammatory cytokines. We also find that CCN1-induced secretory
proteins are elevated in aged human skin in vivo. We propose that CCN1 induces an “Age-Associated Secretory Phenotype”, in
dermal fibroblasts, which mediates collagen reduction and fragmentation in aged human skin. 相似文献
968.
Impact of road construction on giant panda’s habitat and its carrying capacity in Qinling Mountains 下载免费PDF全文
The Qinling giant panda (Ailuropoda melanoleuca) is an endangered endemic species to China. Despite ongoing efforts to ensure its conservation, concerns about maintaining its populations persist. We used GIS fed with data on land use including road network of 2001, third national giant panda survey, and a digital elevation model (DEM) to assess the impact of road construction on giant panda habitat, and estimate the carrying capacity of the Qinling Mountain area. We assessed habitat suitability with a mechanistic model, and conducted correlation analysis to evaluate relationship between the extent of giant panda habitat and amount of sites occupied by pandas within of 5 km × 5 km grid. We also estimated the carrying capacity of the Qinling Mountainous Area.
Our results revealed a significant correlation (R2 = 0.447, P < 0.01) between the number of sites with signs left by giant panda and the extent of habitat within of 5 km × 5 km grid. The minimum habitat area that can support one panda was 10 km2. Before the road network construction, the area of habitat suitable for the panda amounted about 1561 km2 and that of marginally suitable habitat about 1499 km2. The corresponding carrying capacity represented about 240 individuals. After the road network construction, the suitable habitat area was reduced by nearly 30% to 1093 km2. Marginally suitable habitat and unsuitable habitat have both increased by 17% and 1%, respectively. As a result, the potential population size which the habitat could support was reduced to 217 individuals. The study results also suggested that most impacts on habitat from road construction took place in the high elevation areas above 1500 m. However, regarding the impact on the giant panda habitat, road networks developed much more inside the current nature reserves than outside of them. 相似文献
Our results revealed a significant correlation (R2 = 0.447, P < 0.01) between the number of sites with signs left by giant panda and the extent of habitat within of 5 km × 5 km grid. The minimum habitat area that can support one panda was 10 km2. Before the road network construction, the area of habitat suitable for the panda amounted about 1561 km2 and that of marginally suitable habitat about 1499 km2. The corresponding carrying capacity represented about 240 individuals. After the road network construction, the suitable habitat area was reduced by nearly 30% to 1093 km2. Marginally suitable habitat and unsuitable habitat have both increased by 17% and 1%, respectively. As a result, the potential population size which the habitat could support was reduced to 217 individuals. The study results also suggested that most impacts on habitat from road construction took place in the high elevation areas above 1500 m. However, regarding the impact on the giant panda habitat, road networks developed much more inside the current nature reserves than outside of them. 相似文献
969.
970.
Lihua Lai Yinjing Song Yang Liu Qingyun Chen Quan Han Weilin Chen Ting Pan Yuanyuan Zhang Xuetao Cao Qingqing Wang 《The Journal of biological chemistry》2013,288(11):7956-7967
Toll-like receptors (TLRs) play a critical role in the initiation of immune responses against invading pathogens. MicroRNAs have been shown to be important regulators of TLR signaling. In this study, we have found that the stimulation of multiple TLRs rapidly reduced the levels of microRNA-92a (miRNA-92a) and some other members of the miRNA-92a family in macrophages. miR-92a mimics significantly decreased, whereas miR-92a knockdown increased, the activation of the JNK/c-Jun pathway and the production of inflammatory cytokines in macrophages when stimulated with ligands for TLR4. Furthermore, mitogen-activated protein kinase kinase 4 (MKK4), a kinase that activates JNK/stress-activated protein kinase, was found to be directly targeted by miR-92a. Similar to the effects of the miR-92a mimics, knockdown of MKK4 inhibited the activation of JNK/c-Jun signaling and the production of TNF-α and IL-6. In conclusion, we have demonstrated that TLR-mediated miR-92a reduction feedback enhances TLR-triggered production of inflammatory cytokines in macrophages, thus outlining new mechanisms for fine-tuning the TLR-triggered inflammatory response. 相似文献