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961.
Stock AM 《Nature structural & molecular biology》2006,13(10):862-863
962.
963.
Novel 4'-hydroxymethyl branched apiosyl nucleosides were synthesized in this study. The introduction of a hydroxymethyl group in the 4'-position was accomplished by a [3,3]-sigmatropic rearrangement. Apiosyl sugar moiety was constructed by sequential ozonolysis and reductions. The natural bases (uracil, thymine, cytosine, and adenine) were efficiently coupled by a classical glycosyl condensation procedure (persilyated base and TMSOTf). The antiviral activities of the synthesized compounds were evaluated against HIV-1, HSV-1, HSV-2, and HCMV. Compound 18 displayed moderate anti-HCMV activity (EC50 = 20.1 microg/mL) without exhibiting any cytotoxicity up to 100 microM. 相似文献
964.
Rhee JM Pirity MK Lackan CS Long JZ Kondoh G Takeda J Hadjantonakis AK 《Genesis (New York, N.Y. : 2000)》2006,44(4):202-218
The visualization of live cell behaviors operating in situ combined with the power of mouse genetics represents a major step toward understanding the mechanisms regulating embryonic development, homeostasis, and disease progression in mammals. The availability of genetically encoded fluorescent protein reporters, combined with improved optical imaging modalities, have led to advances in our ability to examine cells in vivo. We developed a series of lipid-modified fluorescent protein fusions that are targeted to and label the secretory pathway and the plasma membrane, and that are amenable for use in mice. Here we report the generation of two strains of mice, each expressing a spectrally distinct lipid-modified GFP-variant fluorescent protein fusion. The CAG::GFP-GPI strain exhibited widespread expression of a glycosylphosphatidylinositol-tagged green fluorescent protein (GFP) fusion, while the CAG::myr-Venus strain exhibited widespread expression of a myristoyl-Venus yellow fluorescent protein fusion. Imaging of live transgenic embryonic stem (ES) cells, either live or fixed embryos and postnatal tissues demonstrated that glycosylphosphatidyl inositol- and myristoyl-tagged GFP-variant fusion proteins are targeted to and serve as markers of the plasma membrane. Moreover, our data suggest that these two lipid-modified protein fusions are dynamically targeted both to overlapping as well as distinct lipid-enriched compartments within cells. These transgenic strains not only represent high-contrast reporters of cell morphology and plasma membrane dynamics, but also may be used as in vivo sensors of lipid localization. Furthermore, combining these reporters with the study of mouse mutants will be a step forward in understanding the inter- and intracellular behaviors underlying morphogenesis in both normal and mutant contexts. 相似文献
965.
Soil respiration and the hydrolysis of fluorescein diacetate (FDA) as a measure of total microbial activity were investigated
in central Korea, at three sites that had been changed from abandoned agricultural lands to natural vegetation: rice field
conversion to forest (RF), crop field conversion to shrub (CS), and indigenous forest (IF). Seasonal variations in soil respiration
were affected by soil temperature and, to a lesser extent, by photosynthetically active radiation (PAR) and soil moisture.
The mean annual rate of soil respiration (g CO2 m-2 hr-1) was highest at CS (0.36), followed by IF (0.29) and RF (0.28), whereas the total annual soil respiration (kg CO2 m-2 yr-1) was 2.82 for CS, 2.46 for IF, and 2.40 for RF. Mean annual FDA hydrolysis (μg FDA min-1 g-1 dry soil) was higher at RS (4.56) and IF (4.61) than at CS (3.65). At all three land-use change sites, soil respiration was
only very weakly correlated with FDA hydrolysis. 相似文献
966.
Abuse of drugs can elicit compulsive drug seeking behaviors upon repeated administration, and ultimately leads to the phenomenon of addiction. We developed a procedure for the standardization of microarray gene expression data of rat brain in drug addiction and stored them in a single integrated database system, focusing on more effective data processing and interpretation. Another characteristic of the present database is that it has a systematic flexibility for statistical analysis and linking with other databases. Basically, we adopt an intelligent SQL querying system, as the foundation of our DB, in order to set up an interactive module which can automatically read the raw gene expression data in the standardized format. We maximize the usability of this DB, helping users study significant gene expression and identify biological function of the genes through integrated up-to-date gene information such as GO annotation and metabolic pathway. For collecting the latest information of selected gene from the database, we also set up the local BLAST search engine and nonredundant sequence database updated by NCBI server on a daily basis. We find that the present database is a useful query interface and data-mining tool, specifically for finding out the genes related to drug addiction. We apply this system to the identification and characterization of methamphetamine-induced genes' behavior in rat brain. 相似文献
967.
Female mosquitoes are known to have a magnificent micro-scale pumping system that can transport small quantities of blood very effectively. To understand the dynamic characteristics of blood flow inside female mosquitoes, the measurement technique that is capable of measuring instantaneous flow fields of a biological sample at micrometer scales is required. In this study, the blood-sucking flow inside a female mosquito's food canal was measured in vivo using a micro particle image velocimetry (micro-PIV) velocity field measurement technique with high-temporal resolution. The volumetric flow rate (Q) and the time-averaged feeding speed (V) based on the diameter of the food canal (D) was found to be 5.751×10?3 mm3/s and 0.416 cm/s, respectively. Spectral analysis on the velocity waveform shows a clear peak at 6.1 Hz, indicating distinct pulsatile blood-sucking characteristics. The Womersley number (α) was about 0.117 and the velocity profile of the blood flow inside the proboscis has a parabolic Hagen–Poiseuille flow pattern when α is much smaller than 1. 相似文献
968.
Extended purine sequences on a DNA strand can lead to the formation of triplex DNA in which the third strand runs parallel to the purine strand. Triplex DNA structures have been proposed to play a role in gene expression and recombination and also have potential application as antisense inhibitors of gene expression. Triplex structures have been studied in solution by NMR, but have hitherto resisted attempts at crystallization. Here, we report a novel design of DNA sequences, which allows the first crystallographic study of DNA segment containing triplexes and its junction with a duplex. In the 1.8 A resolution structure, the sugar-phosphate backbone of the third strand is parallel to the purine-rich strand. The bases of the third strand associate with the Watson and Crick duplex via Hoogsteen-type interactions, resulting in three consecutive C(+).GC, BU.ABU (BU = 5-bromouracil), and C(+).GC triplets. The overall conformation of the DNA triplex has some similarity to the B-form, but is distinct from both A- and B-forms. There are large changes in the phosphate backbone torsion angles (particularly gamma) of the purine strand, probably due to the electrostatic interactions between the phosphate groups and the protonated cytosine. These changes narrow the minor groove width of the purine-Hoogsteen strands and may represent sequence-specific structural variations of the DNA triplex. 相似文献
969.
Mutations in the transmembrane natriuretic peptide receptor NPR-B impair skeletal growth and cause acromesomelic dysplasia, type Maroteaux 下载免费PDF全文
Bartels CF Bükülmez H Padayatti P Rhee DK van Ravenswaaij-Arts C Pauli RM Mundlos S Chitayat D Shih LY Al-Gazali LI Kant S Cole T Morton J Cormier-Daire V Faivre L Lees M Kirk J Mortier GR Leroy J Zabel B Kim CA Crow Y Braverman NE van den Akker F Warman ML 《American journal of human genetics》2004,75(1):27-34
The homodimeric transmembrane receptor natriuretic peptide receptor B (NPR-B [also known as guanylate cyclase B, GC-B, and GUC2B]; gene name NPR2) produces cytoplasmic cyclic GMP from GTP on binding its extracellular ligand, C-type natriuretic peptide (CNP). CNP has previously been implicated in the regulation of skeletal growth in transgenic and knockout mice. The autosomal recessive skeletal dysplasia known as "acromesomelic dysplasia, type Maroteaux" (AMDM) maps to an interval that contains NPR2. We sequenced DNA from 21 families affected by AMDM and found 4 nonsense mutations, 4 frameshift mutations, 2 splice-site mutations, and 11 missense mutations. Molecular modeling was used to examine the putative protein change brought about by each missense mutation. Three missense mutations were tested in a functional assay and were found to have markedly deficient guanylyl cyclase activity. We also found that obligate carriers of NPR2 mutations have heights that are below the mean for matched controls. We conclude that, although NPR-B is expressed in a number of tissues, its major role is in the regulation of skeletal growth. 相似文献
970.
We performed comparative proteome analysis of mesenchymal cells and chondrocytes to identify proteins differentially expressed during chondrogenesis. Nine such proteins were identified. Type II collagen, matrilin-1, carbonic anhydrase-II (CA-II), 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthetase-2, and aldo-keto reductase were increased during chondrogenesis, whereas cellular retinoic acid binding protein-I (CRABP-I), CRABP-II, cytoplasmic type 5 actin, and fatty acid binding protein were decreased or almost disappeared. Expression of type II collagen, matrilin-1, PAPS synthetase-2, and CA-II was regulated by extracellular signal-regulated protein kinase, protein kinase C, and p38 kinase, signaling molecules known to regulate chondrogenesis. 相似文献