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901.
基于易错PCR技术的短小芽孢杆菌YZ02脂肪酶基因BpL的定向进化 总被引:1,自引:0,他引:1
利用易错PCR技术对短小芽胞杆菌(Bacillus pumilus)YZ02脂肪酶基因BpL进行两轮定向进化研究, 分别获得最佳突变株BpL1-7和BpL2-1369, 其脂肪酶活力比出发酶分别提高了2倍和6倍。序列分析表明, 突变体BpL2-1369有4个碱基发生了突变: T61C/C147T/A334G/T371A, 其中有3个碱基突变导致了氨基酸的改变。通过SWISS-MODEL数据库模拟脂肪酶的结构显示, 3个突变氨基酸分别位于第1个a螺旋的第3个氨基酸、第4和第5个b折叠之间的转角以及第5个b折叠的第1个氨基酸位置。将野生型脂肪酶基因BpL和进化后的基因BpL2-1369的高效表达产物经Ni-Agarose柱和Sephadex-G75纯化后, 酶学性质测定表明: 突变脂肪酶的比活力比野生型脂肪酶提高了1.31倍, Km值由8.24 mmol/L降低至7.17 mmol/L; 在pH>8.0时的稳定性较野生型脂肪酶有所提高。 相似文献
902.
M. Lebouvier M. Laparie M. Hullé A. Marais Y. Cozic L. Lalouette P. Vernon T. Candresse Y. Frenot David Renault 《Biological invasions》2011,13(5):1195-1208
The suite of environments and anthropogenic modifications of sub-Antarctic islands provide key opportunities to improve our
understanding of the potential consequences of climate change and biological species invasions on terrestrial ecosystems.
The profound impact of human introduced invasive species on indigenous biota, and the facilitation of establishment as a result
of changing thermal conditions, has been well documented on the French sub-Antarctic Kerguelen Islands (South Indian Ocean).
The present study provides an overview of the vulnerability of sub-Antarctic terrestrial communities with respect to two interacting
factors, namely climate change and alien insects. We present datasets assimilated by our teams on the Kerguelen Islands since
1974, coupled with a review of the literature, to evaluate the mechanism and impact of biological invasions in this region.
First, we consider recent climatic trends of the Antarctic region, and its potential influence on the establishment, distribution
and abundance of alien insects, using as examples one fly and one beetle species. Second, we consider to what extent limited
gene pools may restrict alien species’ colonisations. Finally, we consider the vulnerability of native communities to aliens
using the examples of one beetle, one fly, and five aphid species taking into consideration their additional impact as plant
virus vectors. We conclude that the evidence assimilated from the sub-Antarctic islands can be applied to more complex temperate
continental systems as well as further developing international guidelines to minimise the impact of alien species. 相似文献
903.
Katrijn Van Laere Soraya C. França Hein Vansteenkiste Johan Van Huylenbroeck Kathy Steppe Marie-Christine Van Labeke 《Acta Physiologiae Plantarum》2011,33(4):1149-1156
In this study, we analysed morphological, anatomical and physiological effects of polyploidisation in Spathiphyllum
wallisii in order to evaluate possible interesting advantages of polyploids for ornamental breeding. Stomatal density was negatively
correlated with increased ploidy level. Stomatal size increased in polyploids. Tetraploid Spathiphyllum plants had more ovate and thicker leaves. The inflorescence of tetraploids had a more ovate and thicker spathum, a more cylindrical
spadix and a thicker but shorter flower stalk. Biomass production of the tetraploids was reduced, as expressed by lower total
dry weights, and tetraploids produced fewer shoots and leaves compared with their diploid progenitors. Furthermore, tetraploid
Spathiphyllum plants were more resistant to drought stress compared with diploid plants. After 15 days of drought stress, diploids showed
symptoms of wilting, while the tetraploids showed almost no symptoms. Further, measurements of stomatal resistance, leaf water
potential, relative water content and proline content indicated that the tetraploid genotypes were more resistant to drought
stress compared with the diploids. 相似文献
904.
Manuel Porcar 《Systems and synthetic biology》2010,4(1):1-6
Synthetic biology is an engineering approach that seeks to design and construct new biological parts, devices and systems,
as well as to re-design existing components. However, rationally designed synthetic circuits may not work as expected due
to the context-dependence of biological parts. Darwinian selection, the main mechanism through which evolution works, is a
major force in creating biodiversity and may be a powerful tool for synthetic biology. This article reviews selection-based
techniques and proposes strict Darwinian selection as an alternative approach for the identification and characterization
of parts. Additionally, a strategy for fine-tuning of relatively complex circuits by coupling them to a master standard circuit
is discussed. 相似文献
905.
Using the ecosystem services approach for better planning and conservation of urban green spaces: a Finland case study 总被引:6,自引:0,他引:6
Jari Niemelä Sanna-Riikka Saarela Tarja Söderman Leena Kopperoinen Vesa Yli-Pelkonen Seija Väre D. Johan Kotze 《Biodiversity and Conservation》2010,19(11):3225-3243
Ecosystem services are vital for humans in urban regions. However, urban development poses a great risk for the ability of
ecosystems to provide these services. In this paper we first address the most important ecosystem services in functional urban
regions in Finland. Well accessible and good quality recreational ecosystem services, for example, provided by urban nature,
are an important part of a high-quality living environment and important for public health. Vegetation of urban regions can
have a role in carbon dioxide sequestration and thus in climate change mitigation. For instance, estimates of carbon sinks
can be compared to total CO2 emissions of an urban region, and the municipality can aim at both increasing carbon sinks and decreasing CO2 emissions with proper land-use planning. Large and contiguous core nature areas, smaller green areas and ecological connections
between them are the essence of regional ecological networks and are essential for maintaining interconnected habitats for
species and thus biological diversity. Thus, both local and regional level ecological networks are vital for maintaining ecosystem
services in urban regions. The impacts of climate change coupled with land-use and land cover change will bring serious challenges
for maintaining ecosystem services in urban areas. Although not yet widely used in planning practices, the ecosystem services
approach can provide an opportunity for land-use planning to develop ecologically sustainable urban regions. Currently, information
on ecosystem services of urban regions is lacking and there is a need to improve the knowledge base for land-use planning. 相似文献
906.
The genetic material, deoxyribonucleic acid (DNA), contains information about the evolutionary history of life. Both the relationships
amongst organisms and the times of their divergence can be inferred from DNA sequences. Anthropological geneticists use DNA
sequences to infer the evolutionary history of humans and their primate relatives. We review the basic methodology used to
infer these relationships. We then review the anthropological genetic evidence for modern human origins. We conclude that
modern humans evolved recently in Africa and then left to colonize the rest of the world within the last 50,000 years, largely
replacing the other human groups that they encountered. Modern humans likely exchanged genes with Neanderthals prior to or
early during their expansion out of Africa. 相似文献
907.
908.
Yong Liu Ronglei Liu Liangchen Ye Jun Liang Fujun Xuan Qianghua Xu 《Hydrobiologia》2009,618(1):125-137
Portunus trituberculatus is a commercially important species widely spread in the East China Sea. Intraspecific variation of the mitochondrial DNA
cytochrome oxidase subunit I (mtDNA COI) gene was investigated in 213 individuals from six localities (Changjiang Estuary,
Shengsi Islands, Zhoushan Islands, Dongtou Islands, Dinghai Bay, and Quanzhou Bay) ranging from north (31°21′N) to south (24°55′N)
coastal waters of the East China Sea. Overall, a total of 27 mtDNA haplotypes and 21 variable sites were detected in the 787 bp
segment of COI gene. Analysis of mtDNA COI sequence data revealed that crabs from the six localities were characterized by
moderately high haplotypic diversity (h = 0.787 ± 0.026), while sequence divergence values between haplotypes were relatively low (π = 0.00241 ± 0.00098). Each population
was characterized by a single most frequent haplotype, shared among all six localities, and a small number of rare ones, typically
present in only one or two individuals and representative of a specific population. However, neither the neighbor-joining
tree nor the minimum spanning network (MSN) based on the haplotype data exhibited geographical patterns of the six populations.
Mismatch distribution analysis of P. trituberculatus individuals sampled from the six localities suggested that sudden population expansion might have occurred in CJ and SS population
that might be consistent with over-exploitation of the swimming crab. Analysis of molecular variance (AMOVA) and F
ST statistics showed that significant genetic differentiation existed among the SS, ZS, DT, DH, and QZ populations, suggesting
that gene flow might be reduced, even between the geographically close sites, despite the high potential of dispersal. The
possible causes of the observed genetic heterogeneity among the P. trituberculatus populations and the potential applications of the mtDNA COI marker in the artificial breeding and fisheries management are
discussed.
Handling editor: C. Sturmbauer 相似文献
909.
910.
Dandan Liang Lixiao Zhen Tianyou Yuan Jian Huang Fangfei Deng Wuyahan Hong Zhang Lei Pan Yi Liu Erlinda The Zuoren Yu Weidong Zhu Yuzhen Zhang Li Li Luying Peng Jun Li Yi-Han Chen 《PloS one》2014,9(7)
microRNAs (miRNAs) play essential roles in cardiogenesis. The altered expression of miRNAs can result in cardiac malformations by inducing abnormalities in the behavior of cardiac cells. However, the role of miR-10a in the regulation of cardiomyocyte progenitor cells (CMPCs) remains undetermined. In the present study, we found that up- or down-regulation of miR-10a inhibited or promoted the proliferation of human CMPCs, respectively, without affecting their differentiation toward cardiomyocytes. miR-10a bound to GATA6 directly and reduced GATA6 expression. Over-expression of GATA6 greatly attenuated the miR-10a-mediated inhibitory effect on the proliferation of human CMPCs. Thus, our results indicate that miR-10a could effectively modulate the proliferation of human CMPCs by targeting GATA6. The finding provides novel insights into the potency of miR-10a during heart development. 相似文献